Leif M Abrell

Interests

Research

Environmental contaminants, Organic microconstituents, environmental chemistry, mass spectrometry, sensory systems, prebiotic chemistry, global change science, environmental contamination, pollution, informal learning, nature deficit.

Courses

Scholarly Contributions

Chapters

• Olivares, C. I., Abrell, L. M., Chorover, J. D., Simonich, M., Tanguay, R. L., Sierra-Alvarez, R., & Field, J. A. (2016). Identifying toxic biogransformation products of the insensitive munitions compound,2,4-dinitroanisole (DNAN), using liquid chromatography coupled to quadrupole time-of-flight mass spectromety (LC-QToF-MS),. In Assessing Transformation Products of Chemicals by Non-Target and Suspect-Screening-Strategies and Workflows(pp 133-145). Chapter 9 Volume 1: Drewes, J. and Letzel (Eds). doi:10.1021/bk-2016-1241.ch009

Journals/Publications

• Palawat, K., Abrell, L. M., Jones, C. K., Kilungo, A. P., Mclain, J. E., Root, R. A., & Ramirez, M. D. (2025). Arizona rooftop harvested rainwater: How clean is it?. az2112 UA Extension Bulletin, 17.
• Abrell, L. M., Mash, E. A., Field, J. A., Chorover, J. D., Sierra Alvarez, M. R., & Bhumasamudram, J. (2014). Synthesis of 13C and 15N labeled 2,4-dinitroanisole. Journal of Labelled Compounds and Radiopharmaceuticals.
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  Abstract Syntheses of [13C6]-2,4-dinitroanisole (ring-13C6) from [13C6]-anisole (ring-13C6) and[15N2]-2,4-dinitroanisole from anisole using in situ generated acetyl nitrate and [15N]-acetylnitrate, respectively, are described. Treatment of [13C6]-anisole (ring-13C6) with acetyl nitrategenerated in 100% HNO3 gave [13C6]-2,4-dinitroanisole (ring-13C6) in 83% yield. Treatment ofanisole with [15N]-acetyl nitrate generated in 10N [15N]-HNO3 gave [15N2]-2,4-dinitroanisole in44% yield after two cycles of nitration. Byproducts in the latter reaction included [15N]-2-nitroanisole and [15N]-4-nitroanisole.
• Abrell, L. M., Taylor, T., Jardine, K., Yañez-Serrano, A. M., Williams, J., Kunert, N., Atraxo, P., Guenther, A., Hewitt, C. N., House, E., Florentino, A. P., Manzi, A., Higuchi, N., Kesselmeir, J., Behrendt, T., Veres, P. R., Derstroff, B., Fuentes, J., Chambers, J., , Martin, S., et al. (2015). Dimethyl Sulfide in the Amazon Rainforest. Global Biogeochemical Cycles, 29, 19-32.
• Menezes, O., Abrell, L. M., Jon, C., Bianca, F., K, S., James, F. A., Reyes, S., & Rob, R. A. (2024). Assessing strategies to measure hidden per- and polyfluoroalkyl substances (PFAS) in groundwater and to evaluate adsorption remediation efficiency. Chemosphere, 369, 143887.
• Menezes, O., Srivastava, K., Ferreira, B., Field, J., Root, R., Chorover, J., Abrell, L., & Sierra-Alvarez, R. (2024). Assessing strategies to measure hidden per- and polyfluoroalkyl substances (PFAS) in groundwater and to evaluate adsorption remediation efficiencies. Chemosphere, 369. doi:10.1016/j.chemosphere.2024.143887
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  The widespread presence of per- and polyfluoroalkyl substances (PFAS) in the environment, driven by extensive industrial use, has raised global concerns due to their persistence and adverse health effects. Despite the increased regulatory focus on a sub-set of well-known PFAS, over 12,000 compounds exist, many poorly characterized. Our study assessed hidden PFAS concentrations, undetectable by standard LC-MS/MS analysis, in contaminated groundwater. We analyzed total oxidizable precursors (TOP) via TOP assay followed by LC-MS/MS, and total organic fluorine (TOF) via combustion ion chromatography (CIC). Results were compared with those from LC-MS/MS analysis of 25 individual PFAS (∑PFAS25), representing the non-hidden PFAS fraction. We also evaluated the removal of hidden PFAS employing conventional and novel adsorbents. Groundwater samples from drinking water sources and contaminated military sites in the USA showed varying PFAS contamination levels as indicated by TOF values ranging from non-detect (
• Suppes, L. M., Abrell, L. M., Reynolds, K. A., & A, D. P. (2014). Assessment of swimmer behaviors on pool water ingestion. Journal of Water and Health.
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  ABSTRACTEnteric pathogens in pool water can be unintentionally ingested during swimming, increasing the likelihood of acute gastrointestinal illness (AGI). AGI cases in outbreaks are more likely to submerge heads than non-cases, but an association is unknown since outbreak data are self-reported and prone to bias. In the present study, head submersion frequency and duration were observed and analyzed for associations with pool water ingestion measured using ultra high pressure liquid chromatography – tandem mass spectrometry. Frequency of splashes to the face was also quantified. Reliable tools that assess activities associated with pool water ingestion are needed to identify ingestion risk factors and at-risk populations. Objectives were to determine if the observed activities were associated with ingestion, and to test environmental sensor and videography assessment tools. Greater frequency and duration of head submersion were not associated with ingestion, but frequency of splashes to the face, leisurely swimming, and being ≤18 were. Videography was validated for assessing swimmer head submersion frequency. Results demonstrate ingestion risk factors can be identified using videography and urine analysis techniques. Expanding surveys to include questions on leisure swimming participation and frequency of splashes to the face is recommended to improve exposure assessment during outbreak investigations.Keywords: exposure factor; head submersion; ingestion; pool; recreational water; swimming
• Villag??mez-M??rquez, N., Abrell, L., Foley, T., & Ram??rez-Andreotta, M. D. (2023). Organic micropollutants measured in roof-harvested rainwater from rural and urban environmental justice communities in Arizona. Science of The Total Environment, 876, 162662.
• Abrell, L., Chorover, J., Field, J. A., Gomeniuc, A., Hatton, J., He, J., Olshansky, Y., & Sierra-Alvarez, R. (2022).

  Tailored Polyanilines Are High-Affinity Adsorbents for Per- and Polyfluoroalkyl Substances

  . ACS ES&T Water, 2(8), 1402-1410. doi:10.1021/acsestwater.2c00166
• He, J., Gomeniuc, A., Olshansky, Y., Hatton, J., Abrell, L., Field, J., Chorover, J., & Sierra-Alvarez, R. (2022). Enhanced removal of per- and polyfluoroalkyl substances by crosslinked polyaniline polymers. Chemical Engineering Journal, 446. doi:10.1016/j.cej.2022.137246
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  Polyaniline (PANI) and other amine-containing materials have recently been reported as high-affinity, selective adsorbents for per- and polyfluoroalkyl substances (PFAS) remediation, with surface area normalized adsorbed mass significantly exceeding that of granular activated carbon. However, most of these materials have low specific surface area (SSA), suggesting that increasing SSA could result in further enhancement of their ability to sequester PFAS. Herein, we employed a crosslinking method with paraformaldehyde (PFA) to improve the SSA and porous structure of PANI. Several characterization techniques, including elemental composition, N2 adsorption–desorption, zeta potential titration, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, confirmed the success of the crosslinking process. The characterization results demonstrated that crosslinking was a very effective method to synthesize hyper-crosslinked, permanently porous polymers with high SSA (490.3 m2 g−1 for crosslinked PANI_PFA_2.4 compared to 26.3 m2 g−1 for original PANI). Most importantly, crosslinked PANI presented rapid kinetics and high removal efficiency toward perfluorooctanoic acid (PFOA) at environmentally relevant concentrations, the maximum adsorption capacity of crosslinked PANI_PFA_2.4 (98.4 mg g−1) for PFOA remarkably exceeded that of PANI (41.1 mg g−1). Both PANI and crosslinked PANI showed higher sequestration for perfluorosulfonates than their corresponding perfluorocarboxylates, and adsorption increased with increasing fluorocarbon chain length. However, PANI_PFA_2.4 showed lower removal efficiency of multicomponent PFAS mixtures, relative to PANI, which is likely due to competitive PFAS adsorption and to the formation of narrow pores during crosslinking that were easily blocked by preferentially adsorbed long-chain PFAS molecules. The results in this study indicate that crosslinked PANI polymers are promising adsorbents for in situ remediation of PFAS-contaminated groundwater.
• Moses, A., Kilungo, A. P., Mclain, J. E., Root, R. A., Abrell, L. M., Buxner, S. R., & Ramirez, M. D. (2022). Minding the gap: socio‑demographic factors linked to the perceptionof environmental pollution, water harvesting infrastructure,and gardening characteristics. Journal of Environmental Studies and Sciences, 12, 594–610. doi:https://doi.org/10.1007/s13412-022-00769-7
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  With the ongoing need for water conservation, the American Southwest has worked to increase harvested rainwater efforts to meet municipal needs. Concomitantly, environmental pollution is prevalent, leading to concerns regarding the quality of harvested rainwater. Project Harvest, a co-created community science project, was initiated with communities that neighbor sources of pollution. To better understand how a participant’s socio-demographic factors affect home characteristics and rainwater harvesting infrastructure, pinpoint gardening practices, and determine participant perception of environmental pollution, a 145-question “Home Description Survey” was administered to Project Harvest participants (n = 167) by project promotoras (community health workers). Race/ethnicity and community were significantly associated (p < 0.05) with participant responses regarding proximity to potential sources of pollution, roof material, water harvesting device material, harvesting device capacity, harvesting device age, garden amendments, supplemental irrigation, and previous contaminant testing. Further, the study has illuminated the idiosyncratic differences in how underserved communities perceive environmental pollution and historical past land uses in their community. We propose that the collection of such data will inform the field on how to tailor environmental monitoring efforts and results for constituent use, how community members may alter activities to reduce environmental hazard exposure, and how future studies can be designed to meet the needs of environmentally disadvantaged communities.
• Moses, A., Mclain, J. E., Kilungo, A. P., Root, R. A., Abrell, L. M., Buxner, S. R., Sandoval, F., Foley, T., Jones, M., & Ramirez, M. D. (2022). Minding the gap: socio-demographic factors linked to the perception of environmental pollution, water harvesting infrastructure, and gardening characteristics. Journal of Environmental Studies and Sciences.
• Sierra-alvarez, R., Niu, X., Field, J. A., Chorover, J., & Abrell, L. (2022). Analysis of hydrophilic per- and polyfluorinated sulfonates including trifluoromethanesulfonate using solid phase extraction and mixed-mode liquid chromatography-tandem mass spectrometry. Journal of Chromotography A.
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  Abstract Onium salts, widely used as photoacid generators (PAGs) in the semiconductor industry, are receiving increased regulatory scrutiny due to their potential hazardous properties. Evaluating the environmental impacts of these chemicals requires knowledge of the fate of the onium species during photolithography steps, which remains unclear for many PAGs. The current study investigated the fate of four representative sulfonium PAGs using an irradiation setup simulating industrial photolithography. The photolytic fate for three of the four selected onium cations is reported for the first time. All onium compounds reacted rapidly under 254 nm irradiation, and their half-lives ranged from 51 to 214 s with high quantum yields (0.23-0.85). Multiple highly aromatic and hydrophobic photoproducts were characterized using HPLC-DAD and GC-MS; eight PAG photoproducts were identified for the first time. Authentic commercial standards of some of the photoproducts were available, enabling quantitative estimates of recoveries. The molar recovery of aromatic rings based on these quantified photoproducts was in the range of 4.9-71.4%. A homolytic reaction mechanisms is proposed and discussed. The results provide insight on the potential environmental impact pertinent to the use of PAGs, e.g., prediction of residual onium levels and the identity of photoproducts in effluents from semiconductor fabrication facilities.
• Sierra-alvarez, R., Pepel, R. D., Paniego, R., Niu, X., Field, J. A., Chorover, J., & Abrell, L. (2022). Fate of Bis‐(4‐tert‐butyl phenyl)‐iodonium under Photolithography Relevant Irradiation and the Environmental Risk Properties of the formed Photoproducts. Environmental Science and Pollution Research.
• Dennis, L. K., Jung, A. M., Reynolds, K. A., & Abrell, L. M. (2021). Stability of chemical UV filters in sunscreens exposed to vehicle cabin temperatures.. Am J Dermatol Research Reviews, 4(46). doi:10.28933/ajodrr-2021-06-0805
• Sierra-alvarez, R., Menezes, O., Mash, E. A., Kadoya, W. M., Gavazza, S., Field, J. A., & Abrell, L. (2021). Covalent binding with model quinone compounds unveils the environmental fate of the insensitive munitions reduced product 2,4-diaminoanisole (DAAN) under anoxic conditions.. Journal of hazardous materials, 413, 125459. doi:10.1016/j.jhazmat.2021.125459
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  2,4-Dinitroanisole (DNAN) is an insensitive munitions compound expected to replace 2,4,6-trinitrotoluene (TNT). The product of DNAN's reduction in the environment is 2,4-diaminoanisole (DAAN), a toxic and carcinogenic aromatic amine. DAAN is known to become irreversibly incorporated into soil natural organic matter (NOM) after DNAN's reduction. Herein, we investigate the reactions between DAAN and NOM under anoxic conditions, using 1,4-benzoquinone (BQ) and methoxybenzoquinone (MBQ) as model humic moieties of NOM. A new method stopped the fast reactions between DAAN and quinones, capturing the fleeting intermediates. We observed that DAAN incorporation into NOM (represented by BQ and MBQ models) is quinone-dependent and occurs via Michael addition, imine (Schiff-base) formation, and azo bond formation. After dimers are formed, incorporation reactions continue, resulting in trimers and tetramers. After 20 days, 56.4% of dissolved organic carbon from a mixture of DAAN (1 mM) and MBQ (3 mM) had precipitated, indicating an extensive polymerization, with DAAN becoming incorporated into high-molecular-weight humic-like compounds. The present work suggests a new approach for DNAN environmental remediation, in which DNAN anaerobic transformation can be coupled to the formation of non-extractable bound DAAN residues in soil organic matter. This process does not require aerobic conditions nor a specific catalyst.
• Sierra-alvarez, R., Olshansky, Y., Hatton, J., Gomeniuc, A., Field, J. A., Chorover, J., & Abrell, L. (2021). Synthesis and Characterization of Customizable Polyaniline-Derived Polymers and Their Application for Perfluorooctanoic Acid Removal from Aqueous Solution. ACS ES&T Water, 1(6), 1438-1446. doi:10.1021/acsestwater.1c00019
• Sierra-alvarez, R., Pepel, R. D., Paniego, R., Niu, X., Field, J. A., Chorover, J., & Abrell, L. (2021). Bioconcentration potential and microbial toxicity of onium cations in photoacid generators. Environmental Science and Pollution Research, 28(7), 8915-8921. doi:10.1007/s11356-020-12250-5
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  Despite the widespread utilization of onium salts as photoacid generators (PAGs) in semiconductor photolithography, their environmental, health, and safety (EHS) properties remain poorly understood. The present work reports the bioconcentration potential of five representative onium species (four sulfonium and one iodonium compound) by determining the octanol–water partition coefficient (POW) and lipid membrane affinity coefficient (KMA); microbial toxicity was evaluated using the bioluminescent bacterium Aliivibrio fischeri (Microtox bioassay). Four of the oniums exhibited varying degrees of hydrophobic (lipophilic) partitioning (log POW: 0.08–4.12; KMA: 1.70–5.62). A strong positive linear correlation was observed between log POW and KMA (KMA = log POW + 1.76, R2 = 0.99). The bioconcentration factors (log BCF) estimated from POW and KMA for the four oniums ranged from 0.13 to 3.67 L kg−1. Bis-(4-tert-butyl phenyl)-iodonium and triphenylsulfonium had 50% inhibitory concentrations (IC50) of 4.8 and 84.6 μM, whereas the IC50 values of the other three oniums were not determined because these values were higher than their aqueous solubility. Given the increased regulatory scrutiny regarding the use and potential health impacts from onium PAGs, this study fulfills critical knowledge gaps concerning the EHS properties of PAG oniums, enabling more comprehensive evaluation of their environmental impacts and potential risk management strategies.
• Sierra-alvarez, R., Saez, A. E., Pepel, R. D., Paniego, R., Niu, X., Field, J. A., Chorover, J., & Abrell, L. (2021). Photochemical Fate of Sulfonium Photoacid Generator Cations under Photolithography Relevant UV Irradiation. Journal of Photochemistry and Photobiology A-chemistry, 416, 113324. doi:10.1016/j.jphotochem.2021.113324
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  Abstract Onium salts, widely used as photoacid generators (PAGs) in the semiconductor industry, are receiving increased regulatory scrutiny due to their potential hazardous properties. Evaluating the environmental impacts of these chemicals requires knowledge of the fate of the onium species during photolithography steps, which remains unclear for many PAGs. The current study investigated the fate of four representative sulfonium PAGs using an irradiation setup simulating industrial photolithography. The photolytic fate for three of the four selected onium cations is reported for the first time. All onium compounds reacted rapidly under 254 nm irradiation, and their half-lives ranged from 51 to 214 s with high quantum yields (0.23-0.85). Multiple highly aromatic and hydrophobic photoproducts were characterized using HPLC-DAD and GC-MS; eight PAG photoproducts were identified for the first time. Authentic commercial standards of some of the photoproducts were available, enabling quantitative estimates of recoveries. The molar recovery of aromatic rings based on these quantified photoproducts was in the range of 4.9-71.4%. A homolytic reaction mechanisms is proposed and discussed. The results provide insight on the potential environmental impact pertinent to the use of PAGs, e.g., prediction of residual onium levels and the identity of photoproducts in effluents from semiconductor fabrication facilities.
• Tran, T., Chorover, J., Brusseau, M. L., & Abrell, L. (2021). Iron-activated persulfate oxidation degrades aqueous Perfluorooctanoic acid (PFOA) at ambient temperature.. Chemosphere, 281, 130824. doi:10.1016/j.chemosphere.2021.130824
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  Perfluorooctanoic acid (PFOA, C8HF15O2) is an industrial surfactant that is highly resistant to natural breakdown processes such as those mediated by heat, hydrolysis, photolysis, and biodegradation. Many efforts have been developed to breakdown PFOA to less harmful species due to its widespread human exposure and potential toxicity. However, these methods require high temperature or specialized equipment with serious disadvantages of high energy cost for long-term use. We investigated the effectiveness of PFOA degradation by ferrous iron-activated persulfate oxidation (IAPO) under various aqueous geochemical conditions. Approximately 64% of PFOA (initial concentration = 1.64 μmol L-1) was degraded after 4 h under illuminated anoxic conditions at ambient temperature. This degradation rate and magnitude support the potential use of IAPO as a novel inexpensive and environmentally friendly method to remediate PFOA in soil and groundwater.
• Troya, D., Troya, D., Taylor, S., Taylor, S., Qin, C., Qin, C., Hunt, E. A., Hunt, E. A., Dontsova, K., Dontsova, K., Abrell, L., & Abrell, L. (2021). Outdoor dissolution and photodegradation of insensitive munitions formulations IMX-101 and IMX-104: Photolytic transformation pathway and mechanism study.. Chemosphere, 280, 130672. doi:10.1016/j.chemosphere.2021.130672
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  New munition compounds have been developed to replace traditional explosives to prevent unintended detonations. However, insensitive munitions (IM) can leave large proportion of unexploded charge in the field, where it is subjected to photodegradation and dissolution in precipitation. The photolytic reactions occurring on the surfaces of IMX-101 and IMX-104 formulations and the subsequent fate of photolytic products in the environment were thoroughly investigated. The constituents of IMX-101 and IMX-104 formulations dissolve sequentially under rainfall in the order of aqueous solubility: 3-nitro-1,2,4-triazol-5-one (NTO) > nitroguanidine (NQ) > 2,4-dinitroanisole (DNAN) > 1,3,5-hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). A linear relationship between DNAN dissolution and rainwater volume was observed (r2: 0.86-0.99). It was estimated that it would take 16-228 years to completely dissolve these formulation particles under natural environmental conditions in Oracle, AZ. We used LC/MS/MS and GC/MS to examine the dissolution samples from IMX-101 and 104 particles exposed to rainfall and sunlight and found six DNAN photo-transformation products including 2-methoxy-5-nitrophenol, 4-methoxy-3-nitrophenol, 4-methoxy-3-nitroaniline, 2-methoxy-5-nitroaniline, 2,4-dinitrophenol, and methoxy-dinitrophenol, which are in good agreement with computational modeling results of bond strengths. The main DNAN photodegradation pathways are therefore proposed. Predicted eco-toxicity values suggested that the parent compound DNAN, methoxy-nitrophenols, methoxy-nitroanilines and the other two products (2,4-dinitrophenol and methoxy-dinitrophenol) would be harmful to fish and daphnid. Our study provides improved insight about the rain dissolution and photochemical behavior of IM formulations under natural conditions, which helps to form target-oriented strategies to mitigate explosive contamination in military training sites.
• Wong, S., Sierra-alvarez, R., Mash, E. A., Kadoya, W. M., Jagadish, B., Field, J. A., & Abrell, L. (2021). Covalent bonding of aromatic amine daughter products of 2,4-dinitroanisole (DNAN) with model quinone compounds representing humus via nucleophilic addition.. Environmental pollution (Barking, Essex : 1987), 268(Pt B), 115862. doi:10.1016/j.envpol.2020.115862
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  2,4-Dinitroanisole (DNAN) is a component of insensitive munitions (IM), which are replacing traditional explosives due to their improved safety. Incomplete IM combustion releases DNAN onto the soil, where it can leach into the subsurface with rainwater, encounter anoxic conditions, and undergo (a)biotic reduction to aromatic amines 2-methoxy-5-nitroaniline (MENA), 4-methoxy-3-nitroaniline (iMENA, isomer of MENA), and 2,4-diaminoanisole (DAAN). We report here studies of nucleophilic addition mechanisms that may account for the sequestration of aromatic amine daughter products of DNAN into soil organic matter (humus), effectively removing these toxic compounds from the aqueous environment. Because quinones are important moieties in humus, we incubated MENA, iMENA, DAAN, and related analogs with model compounds 1,4-benzoquinone and 2,3-dimethyl-1,4-benzoquinone under anoxic conditions. Mass spectrometry and ultra-high performance liquid chromatography revealed that the aromatic amines had covalently bonded to either carbonyl carbons or ring carbons β to carbonyl carbons of the quinones, producing a mixture of imines and Michael adducts, respectively. These products formed rapidly and accumulated in the one-to four-day incubations. Nucleophilic addition reactions, which do not require catalysis or oxic conditions, are proposed as a mechanism resulting in the binding of DNAN to soil observed in previous studies. To remediate sites contaminated with DNAN or other nitroaromatics, reducing conditions and humus amendments may promote their immobilization into the soil matrix.
• Ramirez, M. D., Ramirez, M. D., Abrell, L. M., Abrell, L. M., Kilungo, A. P., Kilungo, A. P., Mclain, J. E., Mclain, J. E., Root, R. A., & Root, R. A. (2019). Partnering for action: community monitoring of harvested rainwater in underserved, rural, and urban Arizona communities. Water Resources IMPACT.
• Valdez-carrillo, M., Reyes-lopez, J. A., Ramirez-hernandez, J., Carreon-diazconti, C., & Abrell, L. (2020). Pharmaceuticals as emerging contaminants in the aquatic environment of Latin America: a review.. Environmental Science and Pollution Research, 27(36), 44863-44891. doi:10.1007/s11356-020-10842-9
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  Pharmaceutical active compounds (PhACs) are environmentally ubiquitous around the world, and the countries of Latin America (LATAM) are not the exception; however there is still little knowledge of the magnitude and conditions of their occurrence in LATAM and of the environmental consequences of their presence. The present work reviews 79 documents published from 2007 to 2019 on the occurrence, concentrations, and sources of PhACs and hormones in surface water (SW), wastewater (WW), and treated wastewater (TWW) in LATAM and on the circumstances of their release to the environment. Research efforts are reported in only ten countries and confirm the presence of 159 PhACs, mainly analgesics and anti-inflammatories, although extraordinarily high concentrations of carbamazepine (830 μg/L) and ethinylestradiol (6.8 μg/L) were found in Ecuador and Brazil, respectively. The analysis of maximum concentrations and the ecotoxicological risk assessment corroborate that (1) these values exceed the environmental concentrations found in other parts of the world, (2) the environmental risk posed by these concentrations is remarkably high, and (3) there is no statistically significant difference between the maximum concentrations found in WW and those found in TWW. The main source of PhACs in LATAM’s aquatic environment is WW; hence, these countries should direct substantial efforts to develop efficient and cost-effective treatment technologies and plan and apply WW management strategies and regulations. This analysis presents the current states of occurrence, concentrations, and sources of PhACs in the aquatic environment of LATAM and outlines the magnitude of the environmental problem in that part of the world.
• Horne, Y. O., Tran, T., Reynolds, K. A., Parks, J., Beamer, P. I., & Abrell, L. (2019). Seasonal Variation of Water Quality in Unregulated Domestic Wells.. International journal of environmental research and public health, 16(9), 1569. doi:10.3390/ijerph16091569
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  In the United States (U.S.), up to 14% of the population depend on private wells as their primary drinking water source. The U.S. government does not regulate contaminants in private wells. The goals of this study were to investigate the quality of drinking water from unregulated private wells within one mile (1.6 kilometers) of an effluent-dominated river in the arid Southwest, determine differences in contaminant levels between wet and dry seasons, and identify contributions from human sources by specifically measuring man-made organic contaminants (perfluorooctanoic acid (PFOA), perfluorooctane sulfate (PFOS), and sucralose). Samples were collected during two dry seasons and two wet seasons over the course of two years and analyzed for microbial (Escherichia coli), inorganic (arsenic, cadmium, chromium, copper, lead, mercury, nitrate), and synthetic organic (PFOA, PFOS, and sucralose) contaminants. Arsenic, nitrate, and Escherichia coli concentrations exceeded their respective regulatory levels of 0.01 mg/L, 10 mg/L, and 1 colony forming unit (CFU)/100 mL, respectively. The measured concentrations of PFOA and PFOS exceeded the respective Public Health Advisory level. Arsenic, PFOA, PFOS, and sucralose were significantly higher during the dry seasons, whereas E. coli was higher during the wet seasons. While some contaminants were correlated (e.g., As and Hg ρ = 0.87; PFOA and PFOS ρ = 0.45), the lack of correlation between different contaminant types indicates that they may arise from different sources. Multi-faceted interventions are needed to reduce exposure to drinking water above health-based guidelines.
• Jagadish, B., Field, J. A., Wong, S., Sierra-alvarez, R., Mash, E. A., Kadoya, W. M., & Abrell, L. (2019). Coupling reactions between reduced intermediates of insensitive munitions compound analog 4-nitroanisole.. Chemosphere, 222, 789-796. doi:10.1016/j.chemosphere.2019.01.163
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  Explosives, pesticides, and pharmaceuticals contain toxic nitroaromatic compounds that may form even more toxic azo compounds if they encounter reducing conditions in the environment. We investigated the mechanism by which 4,4'-dimethoxyazobenzene forms in anaerobic sludge incubations of 4-nitroanisole, an analog for the insensitive munitions compound 2,4-dinitroanisole (DNAN). Because studies have reported the mechanism to involve the coupling of reduced nitroaromatic intermediates, specifically aromatic amines and nitrosoaromatics, by nucleophilic processes, we abiotically paired 10 mM 4-aminoanisole with 2 mM 4-nitrosoanisole in nitrogen-flushed microcosms. However, only 7 μM of 4,4'-dimethoxyazobenzene had formed after 24 h. We identified the major product to be 4-methoxy-4'-nitrosodiphenylamine. Repeating this experiment in phosphate buffer at pH 5.1, 7.1, and 8.6 demonstrated that the formation of this unexpected product is acid catalyzed. We found that 4-methoxy-4'-nitrosodiphenylamine is more toxic than 4,4'-dimethoxyazobenzene to the bioluminescent bacterium Aliivibrio fischeri, with IC50 values of 0.1 μM and 0.5 μM, respectively. Both products are several orders of magnitude more toxic than reduced 4-nitroanisole intermediates 4-aminoanisole and 4-nitrosoanisole, as well as DNAN and its aromatic amine metabolites. Six-fold more 4,4'-dimethoxyazobenzene formed when we incubated 4-nitrosoanisole with ascorbic acid, a reducing agent, than when we incubated 4-nitrosoanisole with 4-aminoanisole in the absence of ascorbic acid. We therefore suspect that 4-hydroxylaminoanisole, the first reduction product of 4-nitrosoanisole, is a better nucleophile than 4-aminoanisole and couples more readily with 4-nitrosoanisole. Slightly basic and reducing conditions can prevent the formation and persistence of toxic coupling products on sites contaminated with nitroaromatics, i.e. DNAN-contaminated firing ranges.
• Runyon, J. R., Jia, M., Jia, M., Goldstein, M. R., Skeath, P., Abrell, L. M., Sternberg, E. M., Chorover, J. D., Skeath, P. R., Runyon, J. R., & Chorover, J. D. (2019). Dynamic behavior of cortisol and cortisol metabolites in human eccrine sweat. International Journal of Prognostics and Health Management.
• Davis, L. F., Ramirez-andreotta, M. D., Kilungo, A., Buxner, S., Mclain, J. E., & Abrell, L. (2018). Increasing Environmental Health Literacy through Contextual Learning in Communities at Risk.. International journal of environmental research and public health, 15(10), 2203. doi:10.3390/ijerph15102203
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  Environmental health literacy (EHL) has recently been defined as the continuum of environmental health knowledge and awareness, skills and self-efficacy, and community action. In this study, an interdisciplinary team of university scientists, partnering with local organizations, developed and facilitated EHL trainings with special focus on rainwater harvesting and water contamination, in four communities with known environmental health stressors in Arizona, USA. These participatory trainings incorporated participants' prior environmental health risk knowledge and personal experiences to co-create training content. Mixed methods evaluation was conducted via pre-post participant surveys in all four trainings (n = 53). Participants who did not demonstrate baseline environmental science knowledge pre-training demonstrated significant knowledge increase post-training, and participants who demonstrated low self-efficacy (SE) pre-training demonstrated a significant increase in SE post-training. Participants overall demonstrated a significant increase in specific environmental health skills described post-training. The interdisciplinary facilitator-scientist team also reported multiple benefits, including learning local knowledge that informed further research, and building trust relationships with community members for future collaboration. We propose contextual EHL education as a valuable strategy for increasing EHL in environmental health risk communities, and for building academia-community partnerships for environmental health research and action.
• Field, J. A., Wong, S., Sierra-alvarez, R., Mash, E. A., Kadoya, W. M., Field, J. A., & Abrell, L. (2018). Evidence of anaerobic coupling reactions between reduced intermediates of 4-nitroanisole.. Chemosphere, 195, 372-380. doi:10.1016/j.chemosphere.2017.12.083
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  Nitroaromatic compounds are widely used in agricultural pesticides, pharmaceuticals, military explosives, and other applications. They enter the environment via manufacturing and municipal wastewater discharges and releases from agricultural and military operations. Because of their ubiquity and toxicity, they are considered an important class of environmental contaminants. Nitroaromatics are known to undergo reductive transformation to aromatic amines, and under aerobic conditions they are susceptible to coupling reactions which may lead to their irreversible incorporation into soil organic matter. However, there is also evidence of coupling reactions in the absence of oxygen between reduced intermediates of the insensitive munitions compound 2,4-dinitroanisole, leading to the formation of azo dimers. The formation of such products is a concern since they may be more toxic than the original nitroaromatic compounds. The objective of this research is to provide evidence of the anaerobic formation of azo coupling products. 4-Nitroanisole was used as a model compound and was spiked into incubations containing anaerobic granular sludge with H2 as the electron donor. Using liquid chromatography, UV-Vis spectroscopy, and mass spectrometry, the formation of the azo dimer 4,4'-dimethoxyazobenzene was confirmed. However, due to the instability of the azo bond under the reducing conditions of our incubations, the azo dimer did not accumulate. Consequently, 4-aminoanisole was the major product formed in our experiment. Other minor suspected coupling products were also detected in our incubations. The results provide clear evidence for the temporal formation of at least one azo dimer in the anaerobic reduction of a model nitroaromatic compound.
• Li, G., Root, R. A., Sierra-alvarez, R., Root, R. A., Li, G., Khatiwada, R., Field, J. A., Chorover, J., & Abrell, L. (2018). Adsorption and oxidation of 3-nitro-1,2,4-triazole-5-one (NTO) and its transformation product (3-amino-1,2,4-triazole-5-one, ATO) at ferrihydrite and birnessite surfaces.. Environmental pollution (Barking, Essex : 1987), 240, 200-208. doi:10.1016/j.envpol.2018.04.034
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  The emerging insensitive munitions compound (IMC) 3-nitro-1,2,4-triazole-5-one (NTO) is currently being used to replace conventional explosives such as 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but the environmental fate of this increasingly widespread IMC remains poorly understood. Upon release from unexploded solid phase ordinances, NTO exhibits high aqueous solubility and, hence, potential mobilization to groundwater. Adsorption and abiotic transformation at metal oxide surfaces are possible mechanisms for natural attenuation. Here, the reactions at ferrihydrite and birnessite surfaces of NTO and its biotransformation product, 3-amino-1, 2, 4-triazol-5-one (ATO), were studied in stirred batch reactor systems at controlled pH (7.0). The study was carried out at metal oxide solid to solution ratios (SSR) of 0.15, 1.5 and 15 g kg-1. The samples were collected at various time intervals up to 3 h after reaction initiation, and analyzed using HPLC with photodiode array and mass spectrometric detection. We found no detectable adsorption or transformation of NTO upon reaction with birnessite, whereas ATO was highly susceptible to oxidation by the same mineral, showing nearly complete transformation within 5 min at 15 g kg-1 SSR to urea, CO2(g) and N2(g). The mean surface-area-normalized pseudo-first order rate constant (k) for ATO oxidation by birnessite across all SSRs was 0.05 ± 0.022 h-1 m-2, and oxidation kinetics were independent of dissolved O2 concentration. Both NTO and ATO were resistant to oxidation by ferrihydrite. However, NTO showed partial removal from solution upon reaction with ferrihydrite at 0.15 and 1.5 g kg-1 SSR and complete loss at 15 g kg-1 SSR due to strong adsorption. Conversely, ATO adsorption to ferrihydrite was much weaker than that measured for NTO.
• Root, R. A., Olivares, C. I., Sierra-alvarez, R., Root, R. A., Olivares, C. I., Khatiwada, R., Field, J. A., Chorover, J., & Abrell, L. (2018). Oxidation of reduced daughter products from 2,4-dinitroanisole (DNAN) by Mn(IV) and Fe(III) oxides.. Chemosphere, 201, 790-798. doi:10.1016/j.chemosphere.2018.03.020
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  Abiotic transformation of anthropogenic compounds by redox-active metal oxides affects contaminant fate in soil. The capacity of birnessite and ferrihydrite to oxidize the insensitive munitions compound, 2,4-dinitroanisol (DNAN), and its amine-containing daughter products, 2-methoxy-5-nitro aniline (MENA) and 2,4-diaminoanisole (DAAN), was studied in stirred reactors at controlled pH (7.0). Aqueous suspensions were reacted at metal oxide solid to solution mass ratios (SSR) of 0.15, 1.5 and 15 g kg-1 and solutions were analyzed after 0-3 h by high performance liquid chromatography coupled with photodiode array or mass spectrometry detection. Results indicate that DNAN was resistant to oxidation by birnessite and ferrihydrite. Ferrihydrite did not oxidize MENA, but MENA was susceptible to rapid oxidation by birnessite, with nitrogen largely mineralized to nitrite. This is the first report on mineralization of nonphenolic aromatics and the release of mineralized N from aromatic amines following reaction with birnessite. DAAN was oxidized by both solids, but ca. ten times higher rate was observed with birnessite as compared to ferrihydrite at an SSR of 1.5 g kg-1. At 15 g kg-1 SSR, DAAN was removed from solution within 5 min of reaction with birnessite. CO2(g) evolution experiments indicate mineralization of 15 and 12% of the carbon associated with MENA and DAAN, respectively, under oxic conditions with birnessite at SSR of 15 g kg-1. The results taken as a whole indicate that initial reductive (bio)transformation products of DNAN are readily oxidized by birnessite. The oxidizability of the reduced DNAN products was increased with progressive (bio)reduction as reflected by impacts on the oxidation rate.
• Root, R. A., Sierra-alvarez, R., Khatiwada, R., Field, J. A., Chorover, J., & Abrell, L. (2018). Abiotic reduction of insensitive munition compounds by sulfate green rust. Environmental Chemistry, 15(5), 259-266. doi:10.1071/en17221
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  Environmental context There is a growing need to understand how insensitive munitions compounds behave in natural environments, particularly in soils, where non-combusted residues accumulate. Here, we tested the ability of sulfate green rust, a naturally occurring mineral, to transform munitions compounds by reacting with the mineral surface. Our results show that both the munitions compounds and the mineral structures are transformed in an oxidation–reduction reaction that alters the compounds’ environmental fates. Abstract Abiotic transformation of contaminants by redox-active mineral surfaces plays an important role in the fate and behaviour of pollutants in soils and sediments. However, there is very little information on such transformations for the insensitive munitions compounds (IMCs), 3-nitro-1,2,4-triazol-5-one (NTO) and 2,4-dinitroanisole (DNAN), developed in recent years to replace the traditional munition compounds in explosive mixtures. We tested the ability of sulfate green rust to transform NTO and DNAN (0.5 mM) under anoxic conditions at pH 8.4 in laboratory experiments, by using green rust supplied at 10 g kg−1 (w/w) solid concentration. Results indicate that NTO and DNAN underwent rapid abiotic reduction to their organic amine daughter products. NTO was completely transformed to 5-amino-1,2 4-triazol-3-one (ATO) within 20 min of reaction. This is the first report of NTO reduction by a naturally occurring mineral. Similarly, DNAN was rapidly transformed to 2-methoxy-5-nitroaniline (MENA) and 4-methoxy-5-nitroaniline (iMENA). The reduction occurred with an intriguing staggered regioselectivity. Over the first 10 min, the para-nitro group of DNAN was selectively reduced to generate iMENA. Thereafter, the ortho-nitro group was preferentially reduced, generating MENA. Both iMENA and MENA were subsequently transformed to the final reduction product 2,4-diaminoanisol (DAAN) within 1 day. Iron Kα X-ray absorption near-edge spectroscopy (XANES) studies of reacted solids indicated oxidative transformation of the green rust to lepidocrocite-like mineral forms. These results indicate that the IMCs can be rapidly transformed in soil, sediment or aquatic environments containing green rust.
• Suppes, L. M., Reynolds, K. A., Ernst, K. C., & Abrell, L. (2018). Validation of Questionnaire Methods to Quantify Recreational Water Ingestion.. International journal of environmental research and public health, 15(11), 2435. doi:10.3390/ijerph15112435
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  Swimming pool water ingestion volumes are necessary for assessing infection risk from swimming. Pool water ingestion volumes can be estimated by questionnaire or measuring a chemical tracer in swimmer urine. Questionnaires are often preferred to the chemical tracer method because surveys are less time consuming, but no research exists validating questionnaires accurately quantify pool water ingestion volumes. The objective of this study was to explore if questionnaires are a reliable tool for collecting pool water ingestion volumes. A questionnaire was issued at four pool sites in Tucson, Arizona to 46 swimmers who also submitted a urine sample for analyzing cyanuric acid, a chemical tracer. Perceived ingestion volumes reported on the questionnaire were compared with pool water ingestion volumes, quantified by analyzing cyanuric acid in swimmer urine. Swimmers were asked if they swallowed (1) no water or only a few drops, (2) one to two mouthfuls, (3) three to five mouthfuls, or (4) six to eight mouthfuls. One mouthful is the equivalent of 27 mL of water. The majority (81%) of swimmers ingested 27 mL ("one mouthful") on the questionnaire. More than half (52%) of swimmers overestimated their ingestion volume. These findings suggest swimmers are over-estimating pool water ingestion because they perceive one mouthful is
• Olivares, C. I., Sierra-alvarez, R., Olivares, C. I., Madeira, C. L., Kadoya, W. M., Field, J. A., Chorover, J., & Abrell, L. (2017). Environmental Fate of 14C Radiolabeled 2,4-Dinitroanisole in Soil Microcosms.. Environmental science & technology, 51(22), 13327-13334. doi:10.1021/acs.est.7b03699
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  2,4-Dinitrosanisole (DNAN) is an insensitive munitions component replacing conventional explosives. While DNAN is known to biotransform in soils to aromatic amines and azo-dimers, it is seldom mineralized by indigenous soil bacteria. Incorporation of DNAN biotransformation products into soil as humus-bound material could serve as a plausible remediation strategy. The present work studied biotransformation of DNAN in soil and sludge microcosms supplemented with uniformly ring-labeled 14C-DNAN to quantify the distribution of label in soil, aqueous, and gaseous phases. Electron donor amendments, different redox conditions (anaerobic, aerobic, sequential anaerobic-aerobic), and the extracellular oxidoreductase enzyme horseradish peroxidase (HRP) were evaluated to maximize incorporation of DNAN biotransformation products into the nonextractable soil humus fraction, humin. Irreversible humin incorporation of 14C-DNAN occurred at higher rates in anaerobic conditions, with a moderate increase when pyruvate was added. Additionally, a single dose of HRP resulted in an instantaneous increased incorporation of 14C-DNAN into the humin fraction. 14C-DNAN incorporation to the humin fraction was strongly correlated (R2 = 0.93) by the soil organic carbon (OC) amount present (either intrinsic or amended). Globally, our results suggest that DNAN biotransformation products can be irreversibly bound to humin in soils as a remediation strategy, which can be enhanced by adding soil OC.
• Li, G., Weiss, S., Vilcherrez, D., Sierra-alvarez, R., Li, G., Krzmarzick, M. J., Gill, C., Field, J. A., & Abrell, L. (2016). Nitrate Reverses Severe Nitrite Inhibition of Anaerobic Ammonium Oxidation (Anammox) Activity in Continuously-Fed Bioreactors.. Environmental science & technology, 50(19), 10518-10526. doi:10.1021/acs.est.6b01560
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  Nitrite (NO2-) substrate under certain conditions can cause failure of N-removal processes relying on anaerobic ammonium oxidizing (anammox) bacteria. Detoxification of NO2- can potentially be achieved by using exogenous nitrate (NO3-). In this work, continuous experiments in bioreactors with anammox bacteria closely related to "Candidatus Brocadia caroliniensis" were conducted to evaluate the effectiveness of short NO3- additions to reverse NO2- toxicity. The results show that a timely NO3- addition immediately after a NO2- stress event completely reversed the NO2- inhibition. This reversal occurs without NO3- being metabolized as evidence by lack of any 30N2 formation from 15N-NO3-. The maximum recovery rate was observed with 5 mM NO3- added for 3 days; however, slower but significant recovery was also observed with 5 mM NO3- for 1 day or 2 mM NO3- for 3 days. Without NO3- addition, long-term NO2- inhibition of anammox biomass resulted in irreversible damage of the cells. These results suggest that a short duration dose of NO3- to an anammox bioreactor can rapidly restore the activity of NO2--stressed anammox cells. On the basis of the results, a hypothesis about the detoxification mechanism related to narK genes in anammox bacteria is proposed and discussed.
• Madeira, C. L., Speet, S. A., Nieto, C. A., Abrell, L. M., Chorover, J. D., Sierra-Alvarez, R., & Field, J. A. (2016). Sequential anaerobic-aerobic biodegradatin of emerging insenstive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO). Chemospher, 167, 478-484.
• Madeira, C. L., Speet, S. A., Nieto, C. A., Abrell, L. M., Chorover, J. D., Sierra-Alvarez, R., & Field, J. A. (2017). Sequential anaerobic-aerobic biodegradatin of emerging insenstive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO). Chemosphere, 167, 478-484.
• Olivares, C. I., Abrell, L. M., Khatiwada, R., Chorover, J. D., Sierra-Alvarez, R., & Field, J. A. (2016). (Bio)transformation of 2,4-dinitroanisole (DNAN) in soils. J Haz Mater, 304, 214-221.
• Olivares, C. I., Sierra-Alvarez, R., Abrell, L. M., Chorover, J. D., Simonich, M., Tanguay, R. L., & Field, J. A. (2016). Zebrafish embryo toxicity of anaerobic biotransformation products from the insensitive munitions compout 2,4-dintroanisole. Environ. Toxicol. Chem., 35, 2774-2781.
• Olivares, C. I., Sierra-Alvarez, R., Alvarez-Nieto, C., Abrell, L. M., Chorover, J. D., & Field, J. A. (2016). Microbial toxicity and characterization of DNAN (bio)transformation product mixtures. Chemosphere, 154, 499-506.
• Olivares, C. I., Wang, J., Sierra-alvarez, R., Luna, C. D., Field, J. A., & Abrell, L. (2016). Continuous treatment of the insensitive munitions compound N-methyl-p-nitro aniline (MNA) in an upflow anaerobic sludge blanket (UASB) bioreactor.. Chemosphere, 144, 1116-22. doi:10.1016/j.chemosphere.2015.09.092
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  N-methyl-p-nitroaniline (MNA) is an ingredient of insensitive munitions (IM) compounds that serves as a plasticizer and helps reduce unwanted detonations. As its use becomes widespread, MNA waste streams will be generated, necessitating viable treatment options. We studied MNA biodegradation and its inhibition potential to a representative anaerobic microbial population in wastewater treatment, methanogens. Anaerobic biodegradation and toxicity assays were performed and an up-flow anaerobic sludge blanket reactor (UASB) was operated to test continuous degradation of MNA. MNA was transformed almost stoichiometrically to N-methyl-p-phenylenediamine (MPD). MPD was not mineralized; however, it was readily autoxidized and polymerized extensively upon aeration at pH = 9. In the UASB reactor, MNA was fully degraded up to a loading rate of 297.5 μM MNA d(-1). Regarding toxicity, MNA was very inhibitory to acetoclastic methanogens (IC50 = 103 μM) whereas MPD was much less toxic, causing only 13.9% inhibition at the highest concentration tested (1025 μM). The results taken as a whole indicate that anaerobic sludge can transform MNA to MPD continuously, and that the transformation decreases the cytotoxicity of the parent pollutant. MPD can be removed through extensive polymerization. These insights could help define efficient treatment options for waste streams polluted with MNA.
• Olivares, C. I., Sierra-alvarez, R., Olivares, C. I., Krzmarzick, M. J., Khatiwada, R., Field, J. A., Chorover, J., & Abrell, L. (2015). Biotransformation and Degradation of the Insensitive Munitions Compound, 3-Nitro-1,2,4-triazol-5-one, by Soil Bacterial Communities.. Environmental science & technology, 49(9), 5681-8. doi:10.1021/acs.est.5b00511
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  Insensitive munitions (IM) are a new class of explosives that are increasingly being adopted by the military. The ability of soil microbial communities to degrade IMs is relatively unknown. In this study, microbial communities from a wide range of soils were tested in microcosms for their ability to degrade the IM, 3-nitro-1,2,4-triazol-5-one (NTO). All seven soil inocula tested were able to readily reduce NTO to 3-amino-1,2,4-triazol-5-one (ATO) via 3-hydroxyamino-1,2,4-triazol-5-one (HTO), under anaerobic conditions with H2 as an electron donor. Numerous other electron donors were shown to be suitable for NTO-reducing bacteria. The addition of a small amount of yeast extract (10 mg/L) was critical to diminish lag times and increased the biotransformation rate of NTO in nearly all cases indicating yeast extract provided important nutrients for NTO-reducing bacteria. The main biotransformation product, ATO, was degradable only in aerobic conditions, as evidenced by a rise in the inorganic nitrogen species nitrite and nitrate, indicative of nitrogen-mineralization. NTO was nonbiodegradable in aerobic microcosms with all soil inocula.
• Suppes, L. M., Ernst, K. C., Abrell, L. M., & Reynolds, K. A. (2015). Validation and Standardization of Swimming Exposure and Pool Operations Questionnaires. International Journal of Hygiene and Environmental Health..
• Billy, L., Raju, K., Nicholas, P., Field, J. A., Abrell, L. M., & Chorover, J. D. (2015). Adsorption of Novel Insensitive Munitions Compounds at Clay Mineral and Metal Oxide Surfaces. Environmental Chemistry, 12, 74-84.
• Shlizerman, E., Sanders, E., Riffell, J. A., Medina, B., Kutz, J. N., Hinterwirth, A. J., & Abrell, L. (2014). Sensory biology. Flower discrimination by pollinators in a dynamic chemical environment.. Science (New York, N.Y.), 344(6191), 1515-8. doi:10.1126/science.1251041
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  Pollinators use their sense of smell to locate flowers from long distances, but little is known about how they are able to discriminate their target odor from a mélange of other natural and anthropogenic odors. Here, we measured the plume from Datura wrightii flowers, a nectar resource for Manduca sexta moths, and show that the scent was dynamic and rapidly embedded among background odors. The moth's ability to track the odor was dependent on the background and odor frequency. By influencing the balance of excitation and inhibition in the antennal lobe, background odors altered the neuronal representation of the target odor and the ability of the moth to track the plume. These results show that the mix of odors present in the environment influences the pollinator's olfactory ability.
• Suppes, L. M., Abrell, L. M., A, D. P., Gerba, C. P., & Reynolds, K. A. (2014). Assessment of Swimmer Head Submersion Exposures and Pool Water Ingestion.. Journal of Water and Health, 12(2), 269-279.
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  ABSTRACTEnteric pathogens in pool water can be unintentionally ingested during swimming, increasing the likelihood of acute gastrointestinal illness (AGI). AGI cases in outbreaks are more likely to submerge heads than non-cases, but an association is unknown since outbreak data are self-reported and prone to bias. In the present study, head submersion frequency and duration were observed and analyzed for associations with pool water ingestion measured using ultra high pressure liquid chromatography – tandem mass spectrometry. Frequency of splashes to the face was also quantified. Reliable tools that assess activities associated with pool water ingestion are needed to identify ingestion risk factors and at-risk populations. Objectives were to determine if the observed activities were associated with ingestion, and to test environmental sensor and videography assessment tools. Greater frequency and duration of head submersion were not associated with ingestion, but frequency of splashes to the face, leisurely swimming, and being ≤18 were. Videography was validated for assessing swimmer head submersion frequency. Results demonstrate ingestion risk factors can be identified using videography and urine analysis techniques. Expanding surveys to include questions on leisure swimming participation and frequency of splashes to the face is recommended to improve exposure assessment during outbreak investigations.Keywords: exposure factor; head submersion; ingestion; pool; recreational water; swimming
• Vickers, C. E., Torn, M. S., Teixeira, A., Nielsen, L. K., Manzi, A. O., Jardine, K. J., Holm, J. A., Higuchi, N., Garcia, S., Fuentes, J. D., Chambers, J. Q., Alves, E. G., & Abrell, L. (2014). Dynamic balancing of isoprene carbon sources reflects photosynthetic and photorespiratory responses to temperature stress.. Plant physiology, 166(4), 2051-64. doi:10.1104/pp.114.247494
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  The volatile gas isoprene is emitted in teragrams per annum quantities from the terrestrial biosphere and exerts a large effect on atmospheric chemistry. Isoprene is made primarily from recently fixed photosynthate; however, alternate carbon sources play an important role, particularly when photosynthate is limiting. We examined the relative contribution of these alternate carbon sources under changes in light and temperature, the two environmental conditions that have the strongest influence over isoprene emission. Using a novel real-time analytical approach that allowed us to examine dynamic changes in carbon sources, we observed that relative contributions do not change as a function of light intensity. We found that the classical uncoupling of isoprene emission from net photosynthesis at elevated leaf temperatures is associated with an increased contribution of alternate carbon. We also observed a rapid compensatory response where alternate carbon sources compensated for transient decreases in recently fixed carbon during thermal ramping, thereby maintaining overall increases in isoprene production rates at high temperatures. Photorespiration is known to contribute to the decline in net photosynthesis at high leaf temperatures. A reduction in the temperature at which the contribution of alternate carbon sources increased was observed under photorespiratory conditions, while photosynthetic conditions increased this temperature. Feeding [2-(13)C]glycine (a photorespiratory intermediate) stimulated emissions of [(13)C1-5]isoprene and (13)CO2, supporting the possibility that photorespiration can provide an alternate source of carbon for isoprene synthesis. Our observations have important implications for establishing improved mechanistic predictions of isoprene emissions and primary carbon metabolism, particularly under the predicted increases in future global temperatures.
• Werner, C., Wegener, F., Jardine, K. J., Haren, J. V., & Abrell, L. (2014). Phytogenic biosynthesis and emission of methyl acetate.. Plant, cell & environment, 37(2), 414-24. doi:10.1111/pce.12164
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  Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic (13) C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2 . (13) C-labelling of MA and CO2 branch emissions respond within minutes to changes in (13) C-positionally labelled pyruvate solutions fed through the transpiration stream. Strong (13) C-labelling of MA emissions occurred only under pyruvate-2-(13) C and pyruvate-2,3-(13) C feeding, but not pyruvate-1-(13) C feeding. In contrast, strong (13) CO2 emissions were only observed under pyruvate-1-(13) C feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere.
• Abrell, L., Dufour, A. P., Reynolds, K. A., & Suppes, L. M. (2013).

  Assessment of swimmer behaviors on pool water ingestion

  . Journal of Water and Health, 12(2), 269-279. doi:10.2166/wh.2013.123
• Jardine, K. J., Meyers, K., Abrell, L., Alves, E. G., Yanez Serrano, A. M., Kesselmeier, J., Karl, T., Guenther, A., Chambers, J. Q., & Vickers, C. (2013). Emissions of putative isoprene oxidation products from mango branches under abiotic stress. Journal of experimental botany, 64(12).
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  Although several per cent of net carbon assimilation can be re-released as isoprene emissions to the atmosphere by many tropical plants, much uncertainty remains regarding its biological significance. In a previous study, we detected emissions of isoprene and its oxidation products methyl vinyl ketone (MVK) and methacrolein (MACR) from tropical plants under high temperature/light stress, suggesting that isoprene is oxidized not only in the atmosphere but also within plants. However, a comprehensive analysis of the suite of isoprene oxidation products in plants has not been performed and production relationships with environmental stress have not been described. In this study, putative isoprene oxidation products from mango (Mangifera indica) branches under abiotic stress were first identified. High temperature/light and freeze-thaw treatments verified direct emissions of the isoprene oxidation products MVK and MACR together with the first observations of 3-methyl furan (3-MF) and 2-methyl-3-buten-2-ol (MBO) as putative novel isoprene oxidation products. Mechanical wounding also stimulated emissions of MVK and MACR. Photosynthesis under (13)CO2 resulted in rapid (
• Jardine, K., Wegener, F., Abrell, L., van Haren, J., & Werner, C. (2013). Phytogenic biosynthesis and emission of methyl acetate. Plant, cell & environment.
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  Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic (13) C-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2 . (13) C-labelling of MA and CO2 branch emissions respond within minutes to changes in (13) C-positionally labelled pyruvate solutions fed through the transpiration stream. Strong (13) C-labelling of MA emissions occurred only under pyruvate-2-(13) C and pyruvate-2,3-(13) C feeding, but not pyruvate-1-(13) C feeding. In contrast, strong (13) CO2 emissions were only observed under pyruvate-1-(13) C feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C2,3 atoms of pyruvate while the C1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere.
• Olivares, C., Liang, J., Abrell, L., Sierra-Alvarez, R., & Field, J. A. (2013). Pathways of reductive 2,4-dinitroanisole (DNAN) biotransformation in sludge. Biotechnology and bioengineering, 110(6).
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  As the use of the insensitive munition compound 2,4-dinitroanisole (DNAN) increases, releases to the environment may pose a threat to local ecosystems. Little is known about the environmental fate of DNAN and the conversions caused by microbial activity. We studied DNAN biotransformation rates in sludge under aerobic, microaerophilic, and anaerobic conditions, detected biotransformation products, and elucidated their chemical structures. The biotransformation of DNAN was most rapid under anaerobic conditions with H2 as a cosubstrate. The results showed that the ortho nitro group in DNAN is regioselectively reduced to yield 2-methoxy-5-nitroaniline (MENA), and then the para nitro group is reduced to give 2,4-diaminoanisole (DAAN). Both MENA and DAAN were identified as important metabolites in all redox conditions. Azo and hydrazine dimer derivatives formed from the coupling of DNAN reduction products in anaerobic conditions. Secondary pathways included acetylation and methylation of amine moieties, as well as the stepwise O-demethylation and dehydroxylation of methoxy groups. Seven unique metabolites were identified which enabled elucidation of biotransformation pathways. The results taken as a whole suggest that reductive biotransformation is an important fate of DNAN leading to the formation of aromatic amines as well as azo and hydrazine dimeric metabolites.
• Riffell, J. A., Lei, H., Abrell, L., & Hildebrand, J. G. (2013). Neural basis of a pollinator's buffet: Olfactory specialization and learning in Manduca sexta moth. Science, 339(6116), 200-204.
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  PMID: 23223454;Abstract: Pollinators exhibit a range of innate and learned behaviors that mediate interactions with flowers, but the olfactory bases of these responses in a naturalistic context remain poorly understood. The hawkmoth Manduca sexta is an important pollinator for many night-blooming flowers but can learn - through olfactory conditioning - to visit other nectar resources. Analysis of the flowers that are innately attractive to moths shows that the scents all have converged on a similar chemical profile that, in turn, is uniquely represented in the moth's antennal (olfactory) lobe. Flexibility in visitation to nonattractive flowers, however, is mediated by octopamine-associated modulation of antennal-lobe neurons during learning. Furthermore, this flexibility does not extinguish the innate preferences. Such processing of stimuli through two olfactory channels, one involving an innate bias and the other a learned association, allows the moths to exist within a dynamic floral environment while maintaining specialized associations.
• Ruiz, S. H., Wickramasekara, S., Abrell, L., Gao, X., Chefetz, B., & Chorover, J. (2013). Complexation of trace organic contaminants with fractionated dissolved organic matter: implications for mass spectrometric quantification. Chemosphere, 91(3).
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  Interaction with aqueous phase dissolved organic matter (DOM) can alter the fate of trace organic contaminants of emerging concern once they enter the water cycle. In order to probe possible DOM binding mechanisms and their consequences for contaminant detection and quantification in natural waters, a set of laboratory experiments was conducted with aqueous solutions containing various operationally-defined "hydrophilic" and "hydrophobic" freshwater DOM fractions isolated by resin adsorption techniques from reference Suwannee River natural organic matter (SROM). Per unit mass of SROM carbon, hydrophobic acids (HoA) comprised the largest C fraction (0.63±0.029), followed by hydrophilic-neutrals (HiN, 0.11±0.01) and acids (HiA, 0.09±0.017). Aqueous solutions comprising 8mgL(-1) DOC of each SROM fraction were spiked with a concentration range (10-1000μgL(-1)) of bisphenol A (BPA), carbamazepine (CBZ), or ibuprofen (IBU) as model target compounds in 24mM NH4HCO3 background electrolyte at pH 7.4. Contaminant interaction with the SROM fractions was probed using fluorescence spectroscopy, and effects on quantitative analysis of the target compounds were measured using direct aqueous-injection liquid chromatography tandem mass spectrometry (LC-MS/MS). Total quenching was greater for the hydrophilic fractions of SROM and associations were principally with protein-like and fulvic acid-like constituents. Whereas LC-MS/MS recoveries indicated relatively weak interactions with most SROM factions, an important exception was the HiA fraction, which diminished recovery of CBZ and IBU by ca. 30% and 70%, respectively, indicating relatively strong molecular interactions.
• Beamer, P. I., Luik, C. E., Abrell, L., Campos, S., Martínez, M. E., & Sáez, A. E. (2012). Concentration of trichloroethylene in breast milk and household water from Nogales, Arizona. Environmental science & technology, 46(16).
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  The United States Environmental Protection Agency has identified quantification of trichloroethylene (TCE), an industrial solvent, in breast milk as a high priority need for risk assessment. Water and milk samples were collected from 20 households by a lactation consultant in Nogales, Arizona. Separate water samples (including tap, bottled, and vending machine) were collected for all household uses: drinking, bathing, cooking, and laundry. A risk factor questionnaire was administered. Liquid-liquid extraction with diethyl ether was followed by GC-MS for TCE quantification in water. Breast milk underwent homogenization, lipid hydrolysis, and centrifugation prior to extraction. The limit of detection was 1.5 ng/mL. TCE was detected in 7 of 20 mothers' breast milk samples. The maximum concentration was 6 ng/mL. TCE concentration in breast milk was significantly correlated with the concentration in water used for bathing (ρ = 0.59, p = 0.008). Detection of TCE in breast milk was more likely if the infant had a body mass index
• Hernandez-Ruiz, S., Abrell, L., Wickramasekara, S., Chefetz, B., & Chorover, J. (2012). Quantifying PPCP interaction with dissolved organic matter in aqueous solution: combined use of fluorescence quenching and tandem mass spectrometry. Water research, 46(4).
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  The documented presence of pharmaceuticals and personal care products (PPCPs) in water sources has prompted a global interest in understanding their environmental fate. Dissolved organic matter (DOM) can potentially alter the fate of these contaminants in aqueous systems by forming contaminant-DOM complexes. In-situ measurements were made to assess the interactions between three common PPCP contaminants and two distinct DOM sources: a wastewater treatment plant (WWOM) and the Suwannee River, GA (SROM). Aqueous DOM solutions (8.0 mg L(-1) C, pH 7.4) were spiked with a range of concentrations of bisphenol-A, carbamazepine and ibuprofen to assess the DOM fluorophores quenched by PPCP interaction in excitation-emission matrices (EEM). Interaction effects on target analyte (PPCP) concentrations were also quantified using direct aqueous injection ultra high performance liquid chromatography tandem mass spectrometry (LC-MS/MS). At low bisphenol-A concentration, WWOM fluorescence was quenched in an EEM region attributed to microbial byproduct-like and humic acid-like DOM components, whereas carbamazepine and ibuprofen quenched fulvic acid-like fluorophores. Fluorescence quenching of SROM by bisphenol-A and carbamazepine was centered on humic acid-like components, whereas ibuprofen quenched the fulvic acid-like fluorophores. Nearly complete LC-MS/MS recovery of all three contaminants was obtained, irrespective of analyte structure and DOM source, indicating relatively weak PPCP-DOM bonding interactions. The results suggest that presence of DOM at environmentally-relevant concentration can give rise to PPCP interactions that could potentially affect their environmental transport, but these DOM-contaminant interactions do not suppress the accurate assessment of target analyte concentrations by aqueous injection LC-MS/MSMS.
• Jardine, K. J., Monson, R. K., Abrell, L., Saleska, S. R., Arneth, A., Jardine, A., Ishida, F. Y., Serrano, A. M., Artaxo, P., Karl, T., Fares, S., Goldstein, A., Loreto, F., & Huxman, T. (2012). Within-plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and methacrolein. Global Change Biology, 18(3), 973-984.
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  Abstract: Isoprene is emitted from many terrestrial plants at high rates, accounting for an estimated 1/3 of annual global volatile organic compound emissions from all anthropogenic and biogenic sources combined. Through rapid photooxidation reactions in the atmosphere, isoprene is converted to a variety of oxidized hydrocarbons, providing higher order reactants for the production of organic nitrates and tropospheric ozone, reducing the availability of oxidants for the breakdown of radiatively active trace gases such as methane, and potentially producing hygroscopic particles that act as effective cloud condensation nuclei. However, the functional basis for plant production of isoprene remains elusive. It has been hypothesized that in the cell isoprene mitigates oxidative damage during the stress-induced accumulation of reactive oxygen species (ROS), but the products of isoprene-ROS reactions in plants have not been detected. Using pyruvate-2- 13C leaf and branch feeding and individual branch and whole mesocosm flux studies, we present evidence that isoprene (i) is oxidized to methyl vinyl ketone and methacrolein (i ox) in leaves and that i ox/i emission ratios increase with temperature, possibly due to an increase in ROS production under high temperature and light stress. In a primary rainforest in Amazonia, we inferred significant in plant isoprene oxidation (despite the strong masking effect of simultaneous atmospheric oxidation), from its influence on the vertical distribution of i ox uptake fluxes, which were shifted to low isoprene emitting regions of the canopy. These observations suggest that carbon investment in isoprene production is larger than that inferred from emissions alone and that models of tropospheric chemistry and biota-chemistry-climate interactions should incorporate isoprene oxidation within both the biosphere and the atmosphere with potential implications for better understanding both the oxidizing power of the troposphere and forest response to climate change. © 2012 Blackwell Publishing Ltd.
• Jardine, K., Barron-Gafford, G. A., Norman, J. P., Abrell, L., Monson, R. K., Meyers, K. T., Pavao-Zuckerman, M., Dontsova, K., Kleist, E., Werner, C., & Huxman, T. E. (2012). Green leaf volatiles and oxygenated metabolite emission bursts from mesquite branches following light-dark transitions. PHOTOSYNTHESIS RESEARCH, 113(1-3), 321-333.
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  Green leaf volatiles (GLVs) are a diverse group of fatty acid-derived compounds emitted by all plants and are involved in a wide variety of developmental and stress-related biological functions. Recently, GLV emission bursts from leaves were reported following light-dark transitions and hypothesized to be related to the stress response while acetaldehyde bursts were hypothesized to be due to the 'pyruvate overflow' mechanism. In this study, branch emissions of GLVs and a group of oxygenated metabolites (acetaldehyde, ethanol, acetic acid, and acetone) derived from the pyruvate dehydrogenase (PDH) bypass pathway were quantified from mesquite plants following light-dark transitions using a coupled GC-MS, PTR-MS, and photosynthesis system. Within the first minute after darkening following a light period, large emission bursts of both C-5 and C-6 GLVs dominated by (Z)-3-hexen-1-yl acetate together with the PDH bypass metabolites are reported for the first time. We found that branches exposed to CO2-free air lacked significant GLV and PDH bypass bursts while O-2-free atmospheres eliminated the GLV burst but stimulated the PDH bypass burst. A positive relationship was observed between photosynthetic activity prior to darkening and the magnitude of the GLV and PDH bursts. Photosynthesis under (CO2)-C-13 resulted in bursts with extensive labeling of acetaldehyde, ethanol, and the acetate but not the C-6-alcohol moiety of (Z)-3-hexen-1-yl acetate. Our observations are consistent with (1) the "pyruvate overflow" mechanism with a fast turnover time (< 1 h) as part of the PDH bypass pathway, which may contribute to the acetyl-CoA used for the acetate moiety of (Z)-3-hexen-1-yl acetate, and (2) a pool of fatty acids with a slow turnover time (> 3 h) responsible for the C-6 alcohol moiety of (Z)-3-hexen-1-yl acetate via the 13-lipoxygenase pathway. We conclude that our non-invasive method may provide a new valuable in vivo tool for studies of acetyl-CoA and fatty acid metabolism in plants at a variety of spatial scales.
• Jardine, K., Barron-Gafford, G. A., Norman, J. P., Abrell, L., Monson, R. K., Meyers, K. T., Pavao-Zuckerman, M., Dontsova, K., Kleist, E., Werner, C., & Huxman, T. E. (2012). Green leaf volatiles and oxygenated metabolite emission bursts from mesquite branches following light-dark transitions. Photosynthesis research, 113(1-3).
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  Green leaf volatiles (GLVs) are a diverse group of fatty acid-derived compounds emitted by all plants and are involved in a wide variety of developmental and stress-related biological functions. Recently, GLV emission bursts from leaves were reported following light-dark transitions and hypothesized to be related to the stress response while acetaldehyde bursts were hypothesized to be due to the 'pyruvate overflow' mechanism. In this study, branch emissions of GLVs and a group of oxygenated metabolites (acetaldehyde, ethanol, acetic acid, and acetone) derived from the pyruvate dehydrogenase (PDH) bypass pathway were quantified from mesquite plants following light-dark transitions using a coupled GC-MS, PTR-MS, and photosynthesis system. Within the first minute after darkening following a light period, large emission bursts of both C(5) and C(6) GLVs dominated by (Z)-3-hexen-1-yl acetate together with the PDH bypass metabolites are reported for the first time. We found that branches exposed to CO(2)-free air lacked significant GLV and PDH bypass bursts while O(2)-free atmospheres eliminated the GLV burst but stimulated the PDH bypass burst. A positive relationship was observed between photosynthetic activity prior to darkening and the magnitude of the GLV and PDH bursts. Photosynthesis under (13)CO(2) resulted in bursts with extensive labeling of acetaldehyde, ethanol, and the acetate but not the C(6)-alcohol moiety of (Z)-3-hexen-1-yl acetate. Our observations are consistent with (1) the "pyruvate overflow" mechanism with a fast turnover time (3 h) responsible for the C(6) alcohol moiety of (Z)-3-hexen-1-yl acetate via the 13-lipoxygenase pathway. We conclude that our non-invasive method may provide a new valuable in vivo tool for studies of acetyl-CoA and fatty acid metabolism in plants at a variety of spatial scales.
• Wickramasekara, S., Hernández-Ruiz, S., Abrell, L., Arnold, R., & Chorover, J. (2012). Natural dissolved organic matter affects electrospray ionization during analysis of emerging contaminants by mass spectrometry. Analytica chimica acta, 717.
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  Dissolved organic matter (DOM), present in many forms in water, can interfere with analysis of organic contaminants by atmospheric pressure ionization-mass spectrometry. A quantitative analysis of this interference, or matrix effect, on organic contaminant target analyte measurements was carried out using un-fractionated and fractionated dissolved natural organic matter from the Suwannee River, GA (SROM), a standard reference material, that was directly infused into the tandem mass spectrometer during multiple reaction monitoring (MRM) of a suite of endocrine disrupting compounds-pharmaceuticals and personal care products (EDC/PPCPs). Most target analytes suffered signal suppression in the presence of both fractionated and un-fractionated SROM, however greater interferences were measured with fractionated relative to bulk SROM. This finding is consistent with the view of organic matter as a supramolecular association of low molecular mass components having separate charged and structural features revealed only after dissociation.
• Abrell, L., Arneth, A., Artaxo, P., Fares, S., Goldstein, A., Huxman, T., Ishida, F. Y., Jardine, K. J., Jardine, A., Karl, T., Loreto, F., Monson, R. K., Saleska, S. R., & Serrano, A. M. (2011).

  Within‐plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and methacrolein

  . Global Change Biology, 18(3), 973-984. doi:10.1111/j.1365-2486.2011.02610.x
• Ishida, F. Y., Yañez-Serrano, A. M., Saleska, S. R., Rizzo, L. V., Kesselmeier, J., Karl, T., Jardine, K. J., Jardine, A., Huxman, T. E., van Haren, J., Artaxo, P., Arneth, A., & Abrell, L. (2011). Within‐canopy sesquiterpene ozonolysis in Amazonia. Journal of Geophysical Research, 116(19), D19301. doi:10.1029/2011jd016243
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  Through rapid reactions with ozone, which can initiate the formation of secondary organic aerosols, the emission of sesquiterpenes from vegetation in Amazonia may have significant impacts on tropospheric chemistry and climate. Little is known, however, about sesquiterpene emissions, transport, and chemistry within plant canopies owing to analytical difficulties stemming from very low ambient concentrations, high reactivities, and sampling losses. Here, we present ambient sesquiterpene concentration measurements obtained during the 2010 dry season within and above a primary tropical forest canopy in Amazonia. We show that by peaking at night instead of during the day, and near the ground instead of within the canopy, sesquiterpene concentrations followed a pattern different from that of monoterpenes, suggesting that unlike monoterpene emissions, which are mainly light dependent, sesquiterpene emissions are mainly temperature dependent. In addition, we observed that sesquiterpene concentrations were inversely related with ozone (with respect to time of day and vertical concentration), suggesting that ambient concentrations are highly sensitive to ozone. These conclusions are supported by experiments in a tropical rain forest mesocosm, where little atmospheric oxidation occurs and sesquiterpene and monoterpene concentrations followed similar diurnal patterns. We estimate that the daytime dry season ozone flux of -0.6 to -1.5 nmol m(-2) s(-1) due to in-canopy sesquiterpene reactivity could account for 7%-28% of the net ozone flux. Our study provides experimental evidence that a large fraction of total plant sesquiterpene emissions (46%-61% by mass) undergo within-canopy ozonolysis, which may benefit plants by reducing ozone uptake and its associated oxidative damage. (Less)
• Jardine, K., Monson, R. K., Abrell, L. M., Saleska, S. R., Arneth, A., Jardine, A., Karl, T., Fares, S., Goldstein, A., Loreto, F., & Huxman, T. E. (2012). Within-plant isoprene oxidation confirmed by direct emissions of oxidation products methyl vinyl ketone and methacrolein. Global Change Biology, 18, 973-984.
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  Keywords: Amazon; biosphere&amp;#8211;atmosphere interactions; isoprene oxidation; methacrolein; methyl vinyl ketone; reactive oxygen species; temperature stress; thermotoleranceAbstractIsoprene is emitted from many terrestrial plants at high rates, accounting for an estimated 1/3 of annual global volatile organic compound emissions from all anthropogenic and biogenic sources combined. Through rapid photooxidation reactions in the atmosphere, isoprene is converted to a variety of oxidized hydrocarbons, providing higher order reactants for the production of organic nitrates and tropospheric ozone, reducing the availability of oxidants for the breakdown of radiatively active trace gases such as methane, and potentially producing hygroscopic particles that act as effective cloud condensation nuclei. However, the functional basis for plant production of isoprene remains elusive. It has been hypothesized that in the cell isoprene mitigates oxidative damage during the stress-induced accumulation of reactive oxygen species (ROS), but the products of isoprene-ROS reactions in plants have not been detected. Using pyruvate-2-13C leaf and branch feeding and individual branch and whole mesocosm flux studies, we present evidence that isoprene (i) is oxidized to methyl vinyl ketone and methacrolein (iox) in leaves and that iox/i emission ratios increase with temperature, possibly due to an increase in ROS production under high temperature and light stress. In a primary rainforest in Amazonia, we inferred significant in plant isoprene oxidation (despite the strong masking effect of simultaneous atmospheric oxidation), from its influence on the vertical distribution of iox uptake fluxes, which were shifted to low isoprene emitting regions of the canopy. These observations suggest that carbon investment in isoprene production is larger than that inferred from emissions alone and that models of tropospheric chemistry and biota&amp;#8211;chemistry&amp;#8211;climate interactions should incorporate isoprene oxidation within both the biosphere and the atmosphere with potential implications for better understanding both the oxidizing power of the troposphere and forest response to climate change.
• Jardine, K., Serrano, A. Y., Arneth, A., Abrell, L., Jardine, A., Artaxo, P., Alves, E., Kesselmeier, J., Taylor, T., Saleska, S., & Huxman, T. (2011). Ecosystem-scale compensation points of formic and acetic acid in the central Amazon. BIOGEOSCIENCES, 8(12), 3709-3720.
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  Organic acids, central to terrestrial carbon metabolism and atmospheric photochemistry, are ubiquitous in the troposphere in the gas, particle, and aqueous phases. As the dominant organic acids in the atmosphere, formic acid (FA, HCOOH) and acetic acid (AA, CH3COOH) control precipitation acidity in remote regions and may represent a critical link between the terrestrial carbon and water cycles by acting as key intermediates in plant carbon and energy metabolism and aerosol-cloud-precipitation interactions. However, our understanding of the exchange of these acids between terrestrial ecosystems and the atmosphere is limited by a lack of field observations, the existence of biogenic and anthropogenic primary and secondary sources whose relative importance is unclear, and the fact that vegetation can act as both a source and a sink. Here, we first present data obtained from the tropical rainforest mesocosm at Biosphere 2 which isolates primary vegetation sources. Strong light and temperature dependent emissions enriched in FA relative to AA were simultaneously observed from individual branches (FA/AA = 3.0 +/- 0.7) and mesocosm ambient air (FA/AA = 1.4 +/- 0.3). We also present long-term observations of vertical concentration gradients of FA and AA within and above a primary rainforest canopy in the central Amazon during the 2010 dry and 2011 wet seasons. We observed a seasonal switch from net ecosystem-scale deposition during the dry season to net emissions during the wet season. This switch was associated with reduced ambient concentrations in the wet season (FA < 1.3 nmol mol(-1), AA < 2.0 nmol mol(-1)) relative to the dry season (FA up to 3.3 nmol mol(-1), AA up to 6.0 nmol mol(-1)), and a simultaneous increase in the FA/AA ambient concentration ratios from 0.3-0.8 in the dry season to 1.0-2.1 in the wet season. These observations are consistent with a switch between a biomass burning dominated source in the dry season (FA/AA < 1.0) to a vegetation dominated source in the wet season (FA/AA > 1.0). Our observations provide the first ecosystem-scale evidence of bidirectional FA and AA exchange between a forest canopy and the atmosphere controlled by ambient concentrations and ecosystem scale compensation points (estimated to be 1.3 +/- 0.3 nmol mol(-1): FA, and 2.1 +/- 0.4 nmol mol(-1): AA). These results suggest the need for a fundamental change in how future biosphere-atmosphere exchange models should treat FA and AA with a focus on factors that influence net exchange rates (ambient concentrations and ecosystem compensation points) rather than treating emissions and deposition separately.
• Jardine, K., Wegener, F., Abrell, L., van Haren, J., & Werner, C. (2011). Phytogenic biosynthesis and emission of methyl acetate. PLANT CELL AND ENVIRONMENT, 37(2), 414-424.
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  Acetylation of plant metabolites fundamentally changes their volatility, solubility and activity as semiochemicals. Here we present a new technique termed dynamic C-13-pulse chasing to track the fate of C1-3 carbon atoms of pyruvate into the biosynthesis and emission of methyl acetate (MA) and CO2. C-13-labelling of MA and CO2 branch emissions respond within minutes to changes in C-13-positionally labelled pyruvate solutions fed through the transpiration stream. Strong C-13-labelling of MA emissions occurred only under pyruvate-2-C-13 and pyruvate-2,3-C-13 feeding, but not pyruvate-1-C-13 feeding. In contrast, strong (CO2)-C-13 emissions were only observed under pyruvate-1-C-13 feeding. These results demonstrate that MA (and other volatile and non-volatile metabolites) derive from the C-2,C-3 atoms of pyruvate while the C-1 atom undergoes decarboxylation. The latter is a non-mitochondrial source of CO2 in the light generally not considered in studies of CO2 sources and sinks. Within a tropical rainforest mesocosm, we also observed atmospheric concentrations of MA up to 0.6 ppbv that tracked light and temperature conditions. Moreover, signals partially attributed to MA were observed in ambient air within and above a tropical rainforest in the Amazon. Our study highlights the potential importance of acetyl coenzyme A (CoA) biosynthesis as a source of acetate esters and CO2 to the atmosphere.
• Yeomans, L., Muthu, D., Lowery, J. J., Martinez, H. N., Abrell, L., Lin, G., Strom, K., Knapp, B. I., Bidlack, J. M., Bilsky, E. J., & Polt, R. (2011). Phosphorylation of enkephalins: NMR and CD studies in aqueous and membrane-mimicking environments. Chemical biology & drug design, 78(5).
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  Phosphorylation of l-serine-containing enkephalin analogs has been explored as an alternative to glycosylation in an effort to increase blood-brain barrier permeability and CNS bioavailability of peptide pharmacophores. Two enkephalin-based peptides were modified for these studies, a set related to DTLES, a mixed μ/δ-agonist, and one related to DAMGO, a highly selective μ-agonist. Each unglycosylated peptide was compared to its phosphate, its mono-benzylphosphate ester, and its β-d-glucoside. Binding was characterized in membrane preparations from Chinese hamster ovary cells expressing human μ, δ and κ-opiate receptors. Antinociception was measured in mice using the 55 °C tail-flick assay. To estimate bioavailability, the antinociceptive effect of each opioid agonist was evaluated after intracerebroventricular (i.c.v.) or intravenous administration (i.v.) of the peptides. Circular dichroism methods and high-field nuclear magnetic resonance were used in the presence and absence of sodium dodecylsulfate to understand how the presence of a membrane might influence the peptide conformations.
• Abrell, L. M., Jardine, K. J., Sommer, E. D., Saleska, S. R., Huxman, T. E., & Harley, P. C. (2010). Gas phase measurements of pyruvic acid and its volatile metabolites. Environmental science & technology, 44(7).
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  Pyruvic acid, central to leaf carbon metabolism, is a precursor of many volatile organic compounds (VOCs) that impact air quality and climate. Although the pathways involved in the production of isoprenoids are well-known, those of several oxygenated VOCs remain uncertain. We present concentration and flux measurements of pyruvic acid and other VOCs within the tropical rainforest (TRF) biome at Biosphere 2. Pyruvic acid concentrations varied diurnally with midday maxima up to 15 ppbv, perhaps due to enhanced production rates and suppression of mitochondrial respiration in the light. Branch fluxes and ambient concentrations of pyruvic acid correlated with those of acetone, acetaldehyde, ethanol, acetic acid, isoprene, monoterpenes, and sesquiterpenes. While pyruvic acid is a known substrate for isoprenoid synthesis, this correlation suggests that the oxygenated VOCs may also derive from pyruvic acid, an idea supported by leaf feeding experiments with sodium pyruvate which resulted in large enhancements in emissions of both isoprenoids and oxygenated VOCs. While feeding with sodium pyruvate-2-(13)C resulted in large emissions of both (13)C-labeled isoprenoids and oxygenated VOCs, feeding with sodium pyruvate-1-(13)C resulted in only (13)C-labeled isoprenoids. This suggests that acetaldehyde, ethanol, and acetic acid are produced from pyruvic acid via the pyruvate dehydrogenase (PDH) bypass system (in which the 1-C carbon of pyruvic acid is lost as CO(2)) and that acetone is also derived from the decarboxylation of pyruvic acid.
• Jardine, K. J., Henderson, W. M., Huxman, T. E., & Abrell, L. (2010). Dynamic Solution Injection: a new method for preparing pptv-ppbv standard atmospheres of volatile organic compounds. ATMOSPHERIC MEASUREMENT TECHNIQUES, 3(6), 1569-1576.
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  Proton Transfer Reaction-Mass Spectrometry (PTR-MS) and thermal desorption Gas Chromatography-Mass Spectrometry (GC-MS) allow for absolute quantification of a wide range of atmospheric volatile organic compounds (VOCs) with concentrations in the ppbv to pptv range. Although often neglected, routine calibration is necessary for accurate quantification of VOCs by PTR-MS and GC-MS. Several gas calibration methods currently exist, including compressed gas cylinders, permeation tubes, diffusion tubes, and liquid injection. While each method has its advantages and limitations, no single technique has emerged that is capable of dynamically generating known concentrations of complex mixtures of VOCs over a large concentration range (ppbv to pptv) and is technically simple, field portable, and affordable. We present the development of a new VOC calibration technique based on liquid injection with these features termed Dynamic Solution Injection (DSI). This method consists of injecting VOCs (0.1-0.5 mM) dissolved in cyclohexane (PTR-MS) or methanol (GC-MS) into a 1.0 slpm flow of purified dilution gas in an unheated 25 ml glass vial. Upon changes in the injection flow rate (0.5-4.0 mu l min(-1)), new VOC concentrations are reached within seconds to minutes, depending on the compound, with a liquid injection flow rate accuracy and precision of better than 7% and 4% respectively. We demonstrate the utility of the DSI technique by calibrating a PTR-MS to seven different cyclohexane solutions containing a total of 34 different biogenic compounds including volatile isoprenoids, oxygenated and simplicity, the Dynamic Solution Injection method will be of great use to both laboratory and field VOC studies.
• Jardine, K. J., Sommer, E. D., Saleska, S. R., Huxman, T. E., Harley, P. C., & Abrell, L. (2010). Gas phase measurements of pyruvic acid and its volatile metabolites. Environmental Science and Technology, 44(7), 2454-2460.
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  PMID: 20210357;Abstract: Pyruvic acid, central to leaf carbon metabolism, is a precursor of many volatile organic compounds (VOCs) that impact air quality and climate. Although the pathways involved in the production of isoprenoids are well-known, those of several oxygenated VOCs remain uncertain. We present concentration and flux measurements of pyruvic acid and other VOCs within the tropical rainforest (TRF) biome at Biosphere 2. Pyruvic acid concentrations varied diurnally with midday maxima up to 15 ppbv, perhaps due to enhanced production rates and suppression of mitochondrial respiration in the light. Branch fluxes and ambient concentrations of pyruvic acid correlated with those of acetone, acetaldehyde, ethanol, acetic acid, isoprene, monoterpenes, and sesquiterpenes. While pyruvic acid is a known substrate for isoprenoid synthesis, this correlation suggests that the oxygenated VOCs may also derive from pyruvic acid, an idea supported by leaf feeding experiments with sodium pyruvate which resulted in large enhancements in emissions of both isoprenoids and oxygenated VOCs. While feeding with sodium pyruvate-2-13C resulted in large emissions of both 13C-labeled isoprenoids and oxygenated VOCs, feeding with sodium pyruvate-1-l3C resulted in only relabeled isoprenoids. This suggests that acetaldehyde, ethanol, and acetic acid are produced from pyruvic acid via the pyruvate dehydrogenase (PDH) bypass system (in which the 1-C carbon of pyruvic acid is lost as CO2) and that acetone is also derived from the decarboxylation of pyruvic acid. © 2010 American Chemical Society.
• Jardine, K., Abrell, L. M., Kurc, S. A., Huxman, T. E., Ortega, J., & Guenther, A. (2010). Volatile organic compound emissions from Larrea tridentata (creosotebush). Atmospheric Chemistry and Physics, 10, 12191-12206..
• Riffell, J. A., Lei, H., Abrell, L., Hildebrand, J. G., Abrell, L. M., Lei, H., & Hildebrand, J. G. (2013). Neural basis of a pollinator's buffet: olfactory specialization and learning in Manduca sexta. Science (New York, N.Y.), 339(6116).
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  Pollinators exhibit a range of innate and learned behaviors that mediate interactions with flowers, but the olfactory bases of these responses in a naturalistic context remain poorly understood. The hawkmoth Manduca sexta is an important pollinator for many night-blooming flowers but can learn--through olfactory conditioning--to visit other nectar resources. Analysis of the flowers that are innately attractive to moths shows that the scents all have converged on a similar chemical profile that, in turn, is uniquely represented in the moth's antennal (olfactory) lobe. Flexibility in visitation to nonattractive flowers, however, is mediated by octopamine-associated modulation of antennal-lobe neurons during learning. Furthermore, this flexibility does not extinguish the innate preferences. Such processing of stimuli through two olfactory channels, one involving an innate bias and the other a learned association, allows the moths to exist within a dynamic floral environment while maintaining specialized associations.
• Zakai, U. I., Błoch-Mechkour, A., Jacobsen, N. E., Abrell, L., Lin, G., Nichol, G. S., Bally, T., & Glass, R. S. (2010). Synthesis and structure of m-terphenyl thio-, seleno-, and telluroethers. The Journal of organic chemistry, 75(24).
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  Several routes for the synthesis of m-terphenyl thio-, seleno-, and telluroethers were investigated. m-Terphenyl iodides react with diphenyl diselenides or ditellurides (CsOH·H(2)O, DMSO, 110 °C) to give the desired compounds in 19-84% yield which significantly extends the previously reported such reactions because o-benzyne cannot be an intermediate as previously suggested. However, the most general synthetic route was that involving reaction of 2,6-diaryl Grignard reagents with sulfur, selenium, or tellurium electrophiles. The m-terphenyl thio-, seleno-, and telluroethers were characterized spectroscopically and, in one case, by single-crystal X-ray analysis. Certain of these compounds showed atropisomerism and barriers for interconversion of isomers were determined by variable-temperature NMR spectroscopy. The barriers for interconverting the syn and anti atropisomers increase on going from the analogous S to Se to Te compounds. Calculations on this isomerization revealed that the barriers are due to rotation about the aryl-aryl bond and that the barriers for rotation about the aryl-chalcogen bond are much lower.
• Riffell, J. A., Abrell, L., & Hildebrand, J. G. (2008). Physical processes and real-time chemical measurement of the insect olfactory environment. Journal of chemical ecology, 34(7).
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  Odor-mediated insect navigation in airborne chemical plumes is vital to many ecological interactions, including mate finding, flower nectaring, and host locating (where disease transmission or herbivory may begin). After emission, volatile chemicals become rapidly mixed and diluted through physical processes that create a dynamic olfactory environment. This review examines those physical processes and some of the analytical technologies available to characterize those behavior-inducing chemical signals at temporal scales equivalent to the olfactory processing in insects. In particular, we focus on two areas of research that together may further our understanding of olfactory signal dynamics and its processing and perception by insects. First, measurement of physical atmospheric processes in the field can provide insight into the spatiotemporal dynamics of the odor signal available to insects. Field measurements in turn permit aspects of the physical environment to be simulated in the laboratory, thereby allowing careful investigation into the links between odor signal dynamics and insect behavior. Second, emerging analytical technologies with high recording frequencies and field-friendly inlet systems may offer new opportunities to characterize natural odors at spatiotemporal scales relevant to insect perception and behavior. Characterization of the chemical signal environment allows the determination of when and where olfactory-mediated behaviors may control ecological interactions. Finally, we argue that coupling of these two research areas will foster increased understanding of the physicochemical environment and enable researchers to determine how olfactory environments shape insect behaviors and sensory systems.
• Riffell, J. A., Alarcón, R., & Abrell, L. (2008). Floral trait associations in hawkmoth-specialized and mixed pollination systems: Datura wrightii and Agave spp. in the Sonoran Desert. Communicative & integrative biology, 1(1).
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  Variation in floral traits including odor, color and morphology, demonstrate the selective pressures imposed by specific pollinator taxa, such as insects and birds. In southern Arizona, Manduca sexta (Sphingidae) hawkmoths are associated with Datura wrightii (Solanaceae) at both the larval (herbivore) and adult (nectar feeding) stages. However during most of the summer Manduca feeds on "bat-adapted" Agave spp. (Agaveacea) flowers, and only use Datura when it is at peak bloom. Manduca's nectar-host use appears to be mediated through innate odor preferences and olfactory learning; they prefer Datura's "hawkmoth-adapted" traits, which facilitate the maintenance of their coevolutionary relationship, yet they are flexible enough to explore and learn to utilize novel resources, such as agave. This behavioral flexibility is likely responsible for the frequent observation of generalized, or mixed, pollination systems. Given that Manduca visit agave species in southern Arizona, we hypothesize that the differences in flower phenotype between two closely related agave species may be associated with the importance of hawkmoths relative to bats. The southernmost agave, Agave palmeri (Agavacea), exhibits floral traits typical of bat pollination, whereas the northernmost species, Agave chrysantha (Agavacea), exhibits mixed floral traits which appear to be adapted to insects, and to a lesser extent, bats. The differences between these agaves are likely correlated with the geographic overlap in migratory bats from Mexico and resident hawkmoth populations. Thus D. wrightii, A. palmeri and A. chrysantha populations represent a unique system in which to examine the evolution of floral traits in both specialized and mixed pollination systems associated with spatially variable pollinator assemblages.
• Jalbout, A. F., Abrell, L. M., Adamowicz, L. -., Polt, R. L., Apponi, A. J., & Ziurys, L. M. (2007). Sugar synthesis from a gas-phase formose reaction. Astrobiology, 7(3).
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  Prebiotic possibilities for the synthesis of interstellar ribose through a protic variant of the formose reaction under gas-phase conditions were studied in the absence of any known catalyst. The ion-molecule reaction products, diose and triose, were sought by mass spectrometry, and relevant masses were observed. Ab initio calculations were used to evaluate protic formose mechanism possibilities. A bilateral theoretical and experimental effort yielded a physical model for glycoaldehyde generation whereby a hydronium cation can mediate formaldehyde dimerization followed by covalent bond formation leading to diose and water. These results advance the possibility that ion-molecule reactions between formaldehyde (CH(2)O) and H(3)O(+) lead to formose reaction products and inform us about potential sugar formation processes in interstellar space.
• Riffell, J. A., Alarcón, R., Abrell, L., Davidowitz, G., Bronstein, J. L., & Hildebrand, J. G. (2008). Behavioral consequences of innate preferences and olfactory learning in hawkmoth-flower interactions. Proceedings of the National Academy of Sciences of the United States of America, 105(9).
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  Spatiotemporal variability in floral resources can have ecological and evolutionary consequences for both plants and the pollinators on which they depend. Seldom, however, can patterns of flower abundance and visitation in the field be linked with the behavioral mechanisms that allow floral visitors to persist when a preferred resource is scarce. To explore these mechanisms better, we examined factors controlling floral preference in the hawkmoth Manduca sexta in the semiarid grassland of Arizona. Here, hawkmoths forage primarily on flowers of the bat-adapted agave, Agave palmeri, but shift to the moth-adapted flowers of their larval host plant, Datura wrightii, when these become abundant. Both plants emit similar concentrations of floral odor, but scent composition, nectar, and flower reflectance are distinct between the two species, and A. palmeri flowers provide six times as much chemical energy as flowers of D. wrightii. Behavioral experiments with both naïve and experienced moths revealed that hawkmoths learn to feed from agave flowers through olfactory conditioning but readily switch to D. wrightii flowers, for which they are the primary pollinator, based on an innate odor preference. Behavioral flexibility and the olfactory contrast between flowers permit the hawkmoths to persist within a dynamic environment, while at the same time to function as the major pollinator of one plant species.
• Wu, X., Witte, V., Meinwald, J., Attygalle, A. B., & Abrell, L. (2007). Structure and function of Dufour gland pheromones from the crazy ant Paratrechina longicornis. Chemoecology, 17(1), 63-69. doi:10.1007/s00049-006-0365-5
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  Dufour glands of Paratrechina longicornis were analyzed chemically using GC-MS techniques. The glands contained twelve alkanes between C9 and C20 chain length with undecane and tridecane as the main components, six alkenes (1- and 4-undecene, 1-, 4-, and 6- tridecene, and heptadecadiene), two alkyl formates (C11 and C13), and saturated and polyunsaturated acids. Many of the alkanes and alkenes were behaviorally active causing a short lasting attraction of ants with different intensity. Detection of the major gland compound undecane in recruitment trails by in vivo SPME sampling provided evidence for its use as a recruitment pheromone. Both poison gland (formic acid) and Dufour gland (undecane) contents were detected on SPME fibers which had been attacked by the ants.
• Ramilijaona, O., Rakotomalala, V., Fisher, B. L., Clark, V. C., & Abrell, L. (2006). Individual variation in alkaloid content of poison frogs of Madagascar (Mantella; Mantellidae).. Journal of chemical ecology, 32(10), 2219-33. doi:10.1007/s10886-006-9144-6
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  Brightly colored Malagasy poison frogs, Mantella spp., sequester lipophilic, basic alkaloids from arthropod prey for their own chemical defense. Consequently, microsympatric prey diversity is expected to influence alkaloid diversity observed in poison frogs. Twenty-two specimens of three Mantella species from four localities in moist forests of southeastern Madagascar were analyzed individually via gas chromatography-mass spectrometry, revealing that they contain over 80 known alkaloids. Frogs within a locality possessed significantly similar alkaloid content and diversity, while frogs from areas that varied in disturbance, elevation, and/or species showed greater differences. Based on dietary data, the larger frog species Mantella baroni consumed more and larger prey, and showed greater diversity in skin alkaloids than significantly smaller Mantella bernhardi. Additionally, frogs from the most pristine locality had the greatest number of alkaloids, whereas individuals from the most disturbed localities had the least. In a comparison of frog alkaloid profiles over a 10- to 14-yr period, alkaloid turnover, and thus presumably alkaloid-source arthropod turnover, was high in a disturbed locality and low in the pristine primary forest locality. We demonstrate that the nonlethal transcutaneous amphibian stimulator (TAS) is effective for harvesting alkaloids from poison frogs; future studies using this device could obtain larger sample sizes without harming local frog populations.
• Rey, A. M., Pegoraro, E., Lin, G., Haren, J. V., & Abrell, L. (2006). Drought effect on isoprene production and consumption in Biosphere 2 tropical rainforest. Global Change Biology, 12(3), 456-469. doi:10.1111/j.1365-2486.2006.01112.x
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  Isoprene is the most abundant of the hydrocarbon compounds emitted from vegetation and plays a major role in tropospheric chemistry. Models predict that future climate change scenarios may lead to an increase in global isoprene emissions as a consequence of higher temperatures and extended drought periods. Tropical rainforests are responsible for more than 80% of global isoprene emissions, so it is important to obtain experimental data on isoprene production and consumption in these ecosystems under control of environmental variables. We explored isoprene emission and consumption in the tropical rainforest model ecosystem of Biosphere 2 laboratory during a mild water stress, and the relationship with light and temperature. Gross isoprene production (GIP) was not significantly affected by mild water stress in this experiment because the isoprene emitters were mainly distributed among the large, canopy layer trees with deep roots in the lower soil profile where water content decreased much less than the top 30cm. However, as found in previous leaf level and whole canopy studies, the ecosystem gross primary production was reduced by (32%) during drought, and as a consequence the percentage of fixed C lost as isoprene tended to increase during drought, from ca. 1% in wet conditions to ca. 2% when soil water content reached its minimum. GIP correlated very well with both light and temperature. Notably, soil isoprene uptake decreased dramatically during the drought, leading to a large increase in daytime net isoprene fluxes.
• Ziurys, L. M., Ziurys, L. M., Wyckoff, S., Wright, M. C., Woodney, L. M., Womack, M., Veal, J. M., Snyder, L. E., Remijan, A. J., Pater, I. D., Palmer, P., Milam, S. N., Gesmundo, M., Friedel, D. N., Forster, J. R., Choi, S., Apponi, A. J., Abrell, L., & A'hearn, M. F. (2006). Formaldehyde in comets C/1995 O1 (Hale-Bopp), C/2002 T7 (linear), and C/2001 Q4 (NEAT) : Investigating the cometary origin of H2CO. The Astrophysical Journal, 649(2), 1169-1177. doi:10.1086/506501
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  Observations offormaldehyde (H2CO) have been conducted toward comets C/1995 O1 (Hale-Bopp), C/2001 Q4 (NEAT), and C/2002 T7 (LINEAR) using the Arizona Radio Observatory (ARO) 12 m telescope at 1.2 and 2 mm. Aperture synthesis maps of H2CO at 3 mm were made using the Berkeley-Illinois-Maryland Association (BIMA) interferometer toward comet Hale-Bopp. These data indicate that the production rate of H2CO is � 3:7 ; 10 28 s � 1 at � 1 AU in comet Hale-Bopp, using a simple Monte Carlo model, if a nuclear origin for the molecule is assumed. However, maps of H2CO in Hale-Bopp, in comparison with CO, show an extended distribution (rs � 15,000 km) with small-scale structure oriented roughly along the comet-Sun direction. This result suggests a source of H2CO other than the comet nucleus. The extended source of formaldehyde is probably grains composed of a mixture of silicates and organicmaterial.Theproductionrate forH2CO increasestoQ � 1:4 ; 10 29 s � 1 assuming suchanextended grain source. This value implies a Q/Q(H2O) � 1:4%, which is similar to the production rate ratio of Q/Q(H2O) � 4% derived from in situ measurements of H2CO in comet Halley. Production rates for H2CO toward comets C/2002 T7 (LINEAR) and C/2001 Q4 (NEAT) are 1:4 ; 10 27 and 5:6 ; 10 26 s � 1 , respectively, modeled using the extended grain source. The spectra of H2CO measured toward comet C/2002 T7 (LINEAR) show evidence for a second velocity component, most likely arising from comet fragmentation. Subject headingg astrobiology — comets: individual (Hale-Bopp (C/1995 O1), NEAT (C/2001 Q4), LINEAR (C/2002 T7)) — radio lines: solar system — techniques: interferometric
• Barron-gafford, G. A., Pegoraro, E., Murthy, R., Malhi, Y., Lin, G., Haren, J. V., Grieve, K. A., & Abrell, L. (2005). The effect of elevated atmospheric CO2 and drought on sources and sinks of isoprene in a temperate and tropical rainforest mesocosm. Global Change Biology, 11(8), 1234-1246. doi:10.1111/j.1365-2486.2005.00986.x
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  Isoprene is the most abundant volatile hydrocarbon emitted by many tree species and has a major impact on tropospheric chemistry, leading to formation of pollutants and enhancing the lifetime of methane, a powerful greenhouse gas. Reliable estimates of global isoprene emission from different ecosystems demand a clear understanding of the processes of both production and consumption. Although the biochemistry of isoprene production has been studied extensively and environmental controls over its emission are relatively well known, the study of isoprene consumption in soil has been largely neglected. Here, we present results on the production and consumption of isoprene studied by measuring the following different components: (1) leaf and soil and (2) at the whole ecosystem level in two distinct enclosed ultraviolet light-depleted mesocosms at the Biosphere 2 facility: a cottonwood plantation with trees grown at ambient and elevated atmospheric CO2 concentrations and a tropical rainforest, under well watered and drought conditions. Consumption of isoprene by soil was observed in both systems. The isoprene sink capacity of litter-free soil of the agriforest stands showed no significant response to different CO2 treatments, while isoprene production was strongly depressed by elevated atmospheric CO2 concentrations. In both mesocosms, drought suppressed the sink capacity, but the full sink capacity of dry soil was recovered within a few hours upon rewetting. We conclude that soil uptake of atmospheric isoprene is likely to be modest but significant and needs to be taken into account for a comprehensive estimate of the global isoprene budget. More studies investigating the capacity of soils to uptake isoprene in natural conditions are clearly needed.
• Hildebrand, J. G., Stange, G., Nakanishi, K., Mechaber, W. L., Hildebrand, J. G., Guerenstein, P. G., Christensen, T. A., & Abrell, L. (2005). Effect of elevated atmospheric CO2 on oviposition behavior in Manduca sexta moths. Global Change Biology, 11(8), 1272-1282. doi:10.1111/j.1365-2486.2005.00989.x
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  Moths can detect changes in environmental carbon dioxide (CO2) with extremely high sensitivity, but the role of CO2 in the biology of these and other insects is not well understood. Although CO2 has been demonstrated to influence egg-laying (oviposition) behavior of the pyralid moth Cactoblastis cactorum and nectar foraging of the sphingid moth Manduca sexta, information about the generalized role of CO2 in the behavioral biology of these species is lacking. Comparative data are necessary to properly assess how the behaviors of different species may be modified by steadily rising levels of greenhouse gases in the environment. Experiments carried out in Biosphere 2 addressed whether changes in ambient CO2 levels play a role in the oviposition behaviors of M. sexta moths. In the first series of experiments, oviposition was measured inside a flight cage with different levels of nearly ambient or elevated CO2 (400, 800 or 1200ppm). For each concentration, hostplants used as oviposition sites were grown from seed at a CO2 level that matched the environment inside the flight cage. Under homogenous levels of CO2, we observed no significant difference in oviposition behavior at the concentrations tested. In a second series of experiments, two groups of hostplants, each surrounded by a mini free-air CO2 enrichment (FACE) ring, were assembled inside a flight cage. In this choice test, a dynamic plume of artificially high CO2 was generated around one group of test plants, while ambient CO2 was released around the second (control) group. After eggs were counted on both plant groups, M. sexta females showed a small preference for ovipositing on the control plants. Therefore, in contrast to C. cactorum females tested under similar dynamic flow conditions, M. sexta female oviposition was not strongly inhibited by elevated CO2. To investigate this phenomenon further, we used electrophysiological recording and found that the CO2 receptor cells in M. sexta, unlike those in C. cactorum, are not readily affected by elevated levels of ambient CO2. These findings therefore suggest that elevated background levels of CO2 affect the physiology of the CO2 detection system of M. sexta to a lesser extent than that of C. cactorum, and this correlates well with the observed differences in oviposition behavior between the two species under elevated levels of environmental CO2. Hostplants of C. cactorum are crassulacean acid metabolism plants that generate nocturnal CO2 sinks on the cladode surfaces, whereas, M. sexta hostplants are nocturnal sources of respiratory CO2. We hypothesize that the abrupt and continuing increase in global ambient CO2 levels will differentially alter the behavior and physiology of moths that use CO2 sinks and sources as sensory cues to find hostplants.
• Stange, G., Pophof, B., & Abrell, L. (2005). Volatile organic compounds as signals in a plant-herbivore system: electrophysiological responses in olfactory sensilla of the moth Cactoblastis cactorum.. Chemical senses, 30(1), 51-68. doi:10.1093/chemse/bji001
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  The morphological sensillum types on the antennae of male and female Cactoblastis cactorum were visualized by scanning electron microscopy. Electrophysiological recordings were performed for the first time on single olfactory sensilla of C. cactorum. The male sensilla trichodea house a receptor cell responding to the putative pheromone component (9Z,12E)-tetradecadienyl acetate. The sensilla trichodea of the females were much shorter than those of the males and contained specialized receptor cells responding to certain terpenoids, the most frequent being the nerolidol-sensitive cell. The sensilla auricillica and sensilla basiconica of both sexes contained cells responding less specifically to terpenoid compounds as well as to green leaf volatiles. Cells of the sensilla coeloconica responded to aliphatic aldehydes and acids. Eight volatile organic compounds emitted by Opuntia stricta, a host plant of C. cactorum, were identified using gas chromatography-mass spectrometry, beta-caryophyllene being the major compound. Five compounds identified by gas chromatography in the headspace of O. stricta elicited responses in olfactory receptor cells of C. cactorum, nonanal being the most active compound and therefore a candidate attractant of C. cactorum.
• Nakanishi, K., Krane, S., Kim, S. R., & Abrell, L. (2003). Microphysiometric Measurement of PAF Receptor Responses to Ginkgolides. Helvetica Chimica Acta, 86(11), 3776-3786. doi:10.1002/hlca.200390319
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  Microphysiometry was used to evaluate the effects of terpene trilactone and flavonoid constituents of Ginkgo biloba on human platelet-activating-factor receptor (PAFR). Inhibition of the platelet-activating factor response by terpene trilactones was confirmed using this functional assay. Ginkgolide B (GB) and 10-O-benzylGB showed the strongest inhibition (81 and 93%, resp.) of the PAFR response, while the flavonoids rutin, quercetin, and kaempferol showed negligible response inhibition. G. biloba extract mixtures were also tested, and results indicate possible synergistic effects among various components.
• Nakanishi, K., Magil, S. G., Maggiali, F., Labutti, J. N., Kawamura, A., Haupert, G. T., Hamlyn, J. M., Berova, N., & Abrell, L. M. (2001). Biological implication of conformational flexibility in ouabain: observations with two ouabain phosphate isomers.. Biochemistry, 40(19), 5835-44. doi:10.1021/bi0101751
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  Ouabain is a highly polar and unusually potent sodium pump inhibitor that possesses uncommon conformational flexibility in its steroid A-ring moiety. The biological significance of ring flection in the cardiotonic steroids has not been described. Accordingly, we prepared ouabain 1,5,19- and 1,11,19-phosphates. The former stabilizes the steroid A-ring chair conformation and the latter locks the A-ring in the half-boat conformation and decreases flection of the ABC-ring moiety. Using a dog kidney cell line (MDCK) in a pH microphysiometer (Cytosensor), ouabain and its 1,5,19-phosphate at 10(-5) M reduced the rate of extracellular acidification by 15-20%. During inhibitor washout, the rate of recovery from the 1,5,19-phosphate analogue was approximately 3 times faster than ouabain. The 1,11,19-phosphate at 10(-4) M elicited a weak ( approximately 7%) response, and the effects reversed approximately 44-fold faster than ouabain. Studies with purified Na(+),K(+)-ATPase showed that ouabain and its 1,5,19-phosphate analogue were of similar efficacy (EC(50) = 1.1 and 5.2 x 10(-7) M, respectively) and >100-fold more potent than the 1,11,19-phosphate analogue. Studies of the binding kinetics showed that the 1,5,19-phosphate analogue bound 3-fold and dissociated 16-fold faster from the purified Na(+),K(+)-ATPase than ouabain. Both analogues were competitive inhibitors of 3H-ouabain binding. Taken together, these results suggest that the marked conformational flexibility of the A-ring in ouabain ordinarily slows the initial binding of this steroid to the sodium pump. However, once ouabain is bound, flection of the steroidal A- and BC-rings is critical for the maintenance of high-affinity binding. Our results indicate that the ouabain-binding site is comprised of structurally mobile elements and highlight the roles that synchronization between receptor and ligand dynamics play as determinants of biological activity in this system.
• Wang, G. Y., Crews, P., Borgeson, B. M., Avelar, A., & Abrell, L. M. (1998). New hirsutane based sesquiterpenes from salt water cultures of a marine sponge-derived fungus and the terrestrial fungus Coriolus consors. Tetrahedron, 54(26), 7335-7342. doi:10.1016/s0040-4020(98)00398-6
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  Abstract Five new cyclic sesquiterpenes, hirsutanols A (6), B (7), C (8), hirsutanol D (9), and ent-gloeosteretriol (10) and a new diketopiperazine (14) were isolated from salt water cultures of two fungi. Sesquiterpenes 6–8 and 10 were obtained from an unidentified fungus separated from an Indo-Pacific sponge Haliclona sp. while 9 and 14 were produced by the terrestrial fungus Coriolus consors cultured under both sea water and deionized water media. Hirsutanol A (6) and ent-gloeosteretriol (10) were found to be anti-microbial (Bacillus subtilus) active. All structures were elucidated by spectroscopic methods.
• Abrell, L. (1997). Investigations of Natural Products from Marine Sponge Derived Fungi. California Sea Grant College Program.
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  Author(s): Abrell, Leif M. | Abstract: Research results described here are from experiments conducted in organic chemistry and marine microbiology. Sponge derived chemistry has provided the marine natural products field with a higher percentage of bioactive leads than temstrial plants or microorganisms. Inspection of these bioactive leads reveals structure types that occur in more than one Demosponge or invertebrate species. It has been hypothesized that this trend indicates complex biosyntheses occmring which include microorganisms associated with the sponges. This theme built on circumstantial evidence is discussed first.Initially we investigated jasplakinolide's occurrence from unrelated sponges including Jaspis aff. johnstoni. Fungi were cultured from this sponge to test the possibility of microorganism biosynthetic involvement. From an unidentified culture we discovered the coriolins, previously known from the temstrial fungus Coriolus consors, and new sesquiterpenes named the chloriolins. We tested the biosynthetic potential of C. consors by growing it in liquid broths with varied salt and fresh water media. We characterized a new coriolin type compound and new and known piperazine diones.Fungi were cultured from the sponge Jaspis aff. coriacea including one strain identified as Aspergillus ochraceus. This fungus produced novel chlorinated polyketides named chlorocarolides which appear to have no ecological connection with sponge's known metabolites. However they do appear analogous to the known Aspergillus metabolite carotic acid. Relative stereochemistry of the chlorocarolides was solved by 1H NMR coupling and molecular modeling analysis.Our fungi library isolated from sponge tissue provided culture extracts screened in two ways: for bioactivity using in-house and off-campus cancer-based bioassays, and for large molecular weight compounds using electrospray ionization mass spectrometry (ESIMS). Polyketides isolated include new nectriapyrones and the novel compound 14,15-secocurvularin. ESIMS results assisted our dereplication process of known compounds isolated.We have shown sponges are a good source for isolating fungi cultures and these cultures may be extracted and purified to provide new and bioactive metabolites from polyketide, terpene, and polypeptide structure classes. Our results indicate that the culturable fungi do not influence the biosynthesis of sponges as once hypothesized and that other classes of microorganisms may merit investigation for their ability to influence sponge metabolite biosynthesis.
• Crews, P., Borgeson, B. M., & Abrell, L. M. (1996). A new polyketide, secocurvularin, from the salt water culture of a sponge derived fungus. Tetrahedron Letters, 37(50), 8983-8984. doi:10.1016/s0040-4039(96)02108-9
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  Abstract The salt water culture of an unidentified fungus separated from the Indo-Pacific sponge Spirastrella vagabunda has yielded a new mildly antibiotic polyketide, 14,15-secocurvularin ( 1 ).
• Crews, P., Borgeson, B. M., & Abrell, L. M. (1996). Chloro polyketides from the cultured fungus (Aspergillus) separated from a marine sponge. Tetrahedron Letters, 37(14), 2331-2334. doi:10.1016/0040-4039(96)00277-8
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  Abstract The salt water culture of Aspergillus ?ochraceus separated from the Indo-Pacific sponge Jaspis cf. coriacea has yielded two new chlorine containing polyketides, chlorocarolide A ( 1a ) and B ( 1b ). These compounds have an overall structural analogy to carolic acid whose biosynthesis has been intensely studied. The structures and stereochemical features of the chlorocarolides are reported. Also noted are the similarities of their α-methylene-γ-butyrolactones to those of the litsenolides and mahubenolides, both derived from plants.
• Crews, P., Cheng, X. C., & Abrell, L. M. (1994). New nectriapyrones by salt water culture of a fungus separated from an Indo-Pacific sponge. Tetrahedron Letters, 35(49), 9159-9160. doi:10.1016/0040-4039(94)88453-6
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  Abstract The salt water culture of an unidentified fungus separated from an Indo-Pacific marine sponge has yielded new tetraketide natural products, demethyl nectriapyrone A ( 1 ) and nectriapyrone B ( 2 ). These α-pyrone containing compounds are analogous to nectriapyrone ( 3 ), previously reported from a terrestrial fungus.
• Varoglu, M., Lobkovsky, E. B., Crews, P., Clardy, J., Cheng, X. C., & Abrell, L. (1994). Chloriolins A-C, Chlorinated Sesquiterpenes Produced by Fungal Cultures Separated from a Jaspis Marine Sponge. Journal of Organic Chemistry, 59(21), 6344-6348. doi:10.1021/jo00100a041
• Rodriguez, J., Riguera, R., Quinoa, E., Peters, B. M., Crews, P., & Abrell, L. M. (1992). The structures and stereochemistry of cytotoxic sesquiterpene quinones from dactylospongia elegans. Tetrahedron, 48(32), 6667-6680. doi:10.1016/s0040-4020(01)80012-0
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  The cytotoxicity of a crude extract from Dactylospongia elegans stimulated a search for the active constituents. The structures and absolute stereochemistry are elucidated for four new 9, 11,18, 19, and thirteen previously described compounds, 3, 4, 6a, 7, 8, 10, 12 - 17, 21. These compounds were isolated from collections of D. elegans obtained from three different Indo-Pacific regions, Fiji, Papua New Guinea, and Thailand. This species appears to elaborate a broader range of the mixed biogenesis sesquiterpene-hydroquinone (-quinone) metabolites in comparison to those of other sponges or seaweeds. Three compounds, 4, 9, and 13, were potent (IC50's were less than 1 μg/mL). The quinone ring appears to be essential for this in vitro activity. © 1992.

Presentations

• Abrell, L. M. (2024, Apr). Environmental Health in Arid Southwestern U.S.. Epsilon Eta, Pre-Professional Environmental Fraternity, Earth Day. UA: Epsilon Eta, Pre-Professional Environmental Fraternity.
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  A professional panelto share career path and research for 75 students ahead of their entry into professional fieldS, followed by a panel discussion and mixer with students.
• Abrell, L. M. (2024, Novemeber). PFAS Knowledge Gaps. Promoting Collaborations in PFAS and Health ResearchSouthwest Environmental Health Science Center.
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  Invited presentation for an interdisciplinary conversation to promote collaborative research on PFAS and human health, where attendees mingled over lunch and poster session, listened to lightning talks on project ideas, and shares in roundtable discussions with colleagues and community members.
• Abrell, L. M. (2024, Sept). Analytical chemistry beyond the planetary boundary. departmental seminar. UA: Environmental Science Dept.
• Ramirez, M. D., Sandhaus, S., Sandoval, F., Kilungo, A. P., Mclain, J. E., Root, R. A., Abrell, L. M., Buxner, S. R., Kaufmann, D. B., Cortez, I., Theresa, F., Margaret, D., Lisa, O., Palawat, K., Norma, V., Annabelle, G., & Tasnim, A. (2021). Building a transdisciplinary, bilingual community science program to advance environmental health in underserved communities. Citizen Science AssociationCitizen Science Association.
• Ramirez, M. D., Abrell, L. M., Mclain, J. E., Kilungo, A. P., Root, R. A., Sandoval, F., Solis-Leon, J., Moses, A., Davis, L., Villagomez, N., & Kaufmann, D. (2019, March). Project Harvest Be Informed. Grow Smarter. Brown Bag Seminar,. Tucson, AZ: Water Research Resource Center, Villagomez-Marquez N. Davis L, and Kaufmann D,.
• Ramirez, M. D., Abrell, L. M., Mclain, J. E., Kilungo, A. P., Root, R. A., Sandoval, F., Solis-Leon, J., Moses, A., Davis, L., Villagomez, N., & Kaufmann, D. (2019, March). Project Harvest Be Informed. Grow Smarter. Water Research Resource Center Brown Bag Seminar. Tucson, AZ: Water Research Resource Center.
• Ramirez, M. D., Ramirez, M. D., Davis, L., Davis, L., Buxner, S. R., Buxner, S. R., Kilungo, A. P., Kilungo, A. P., Root, R. A., Root, R. A., Mclain, J. E., Mclain, J. E., Abrell, L. M., Abrell, L. M., Sandoval, F., & Sandoval, F. (2019, March). Effect of environmental monitoring method on participant self-efficacy for science in underrepresented communities. Citizen Science Conference. Raleigh, North Carolina: Citizen Science Association.
• Root, R. A., Kilungo, A. P., Mclain, J. E., Abrell, L. M., & Ramirez, M. D. (2019, April). Project Harvest: A Co-Created Citizen Science Rainwater Harvesting Program in Rural and Urban Arizona Communities. 2nd Cobre Valley Forum on Water. Globe, Gila County, Arizona..
• Mclain, J. E., Fitzsimmons, K., Meixner, T., Abrell, L. M., & Lynch, R. (2018, March). Might recycled water solve the problem of toxin-producing algae?. Science of the Environment Earth Day Student Presentation. Tucson, Arizona: University of Arizona Department of Soil, Water and Environmental Science.
• Abrell, L. M., Ramirez, M. D., Kilungo, A. P., Mclain, J. E., & Root, R. (2017, September). Survey of contaminants in harvested rainwater from a southern Arizona pilot study. 14th Biennial Conference of Science & Management on the Colorado Plateau & Southwest Region.
• Mclain, J. E., Kilungo, A. P., Ramirez, M. D., Abrell, L. M., Root, R., & Sandoval, F. (2017, September). Teaching harvested rainwater microbiology in Arizona communities: lessons learned. 14th Biennial Conference of Science & Management on the Colorado Plateau & Southwest Region.
• Ramirez, M. D., Abrell, L. M., Mclain, J. E., Kilungo, A. P., Root, R., Sandoval, F., & Sandhaus, S. (2017, September). Community science: public participation in harvested water and soil monitoring. 14th Biennial Conference of Science & Management on the Colorado Plateau & Southwest Region.
• Root, R., Abrell, L. M., Ramirez, M. D., Mclain, J. E., & Kilungo, A. P. (2017, September). Does the dose make the poison: the presence of metal(liods) in harvested rooftop rainwater. 14th Biennial Conference of Science & Management on the Colorado Plateau & Southwest Region.
• Mclain, J. E., Abrell, L. M., Root, R., Allen, N., & Knerl, A. (2014, March). Rainwater harvesting from Tucson rooftops: can we promote water conservation and protect human health?. Pima Association of Governments Seminar Series. Tucson, Arizona: Pima Association of Governments.
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  Water conservation practices that use non-traditional water sources are becoming increasingly important to closing the gap between water supply and demand in the Western United States, where climate change and increasing population are placing unprecedented pressures on potable water supplies. Since the inception of its rainwater harvesting incentives/rebate program in 2011, the City of Tucson has trained hundreds of residents on construction and use of harvesting systems, and has provided many thousands of dollars in rebates following installation. Yet, no water quality standards exist for the use of harvested rainwater, despite the fact that this non-traditional water source can be utilized for irrigation of food crops, residential landscapes, and at other sites with high probability of human contact. This talk discussed results of a summer 2013 study that analyzed microbiological and chemical constituents of rainwater harvested from two rooftop systems, and our plans to leverage these results for making a comprehensive water quality study using a volunteer network of Tucson citizens.
• McLain, J. E., Abrell, L. M., Root, R., Allen, N., & Knerl, A. (2013, May). Assessing biological and chemical quality of harvested rainwater in Arizona: can in-line carbon filters decrease health risks?. Quarterly Meeting: Rainwater/Stormwater Professionals Network. Tucson, Arizona: Rainwater/Stormwater Professionals Network.
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  Presented to audience of 25 researchers, students, and stormwater professionals.

Poster Presentations

• Abrell, L. M. (2021, November). Measurement and characterization of PFAS and organic contaminants in citizen scientists' roof harvested rainwater. American Society for Mass Spectrometry 69th Annual Conference. Philadelphia: ASMS.
• Abrell, L. M., Barrientes, D., Amistadi, M. K., & Chorover, J. D. (2021, October). Total organic fluorine analysis for total PFAS mass estimate – by combustion ion chromatography. American Chemical Society Rocky Mountain Regional Meeting, Oct 20-23, 2021. Tucson, AZ USA: American Chemical Society.
• Abrell, L. M., Villagomez-Marquez, N., Henson, C., Palawat, K., Foley, T., Chorover, J. D., & Ramirez, M. D. (2021). Measurement and characterization of PFAS and organic contaminants in citizen scientists' roof harvested rainwater. 69th ASMS Conference on Mass Spectrometry and Allied Topics. Philadelphia, PA.: 69th ASMS Conference on Mass Spectrometry and Allied Topics.
• Ramirez, M. D., Abrell, L. M., Buxner, S. R., Cortez, I., Davis, L., Dewey, M., Foley, T., Henriquez, P., Jones, M., Kaufmann, D., Kilungo, A. P., Mclain, J. E., Ochoa, L., Root, R. A., Sandhaus, S., Sandoval, F., Ramirez, M. D., Abrell, L. M., Buxner, S. R., , Cortez, I., et al. (2021). Engaging Diverse Communities for Environmental Health Justice. National Science Foundation’s AISL PI meetingNational Science Foundation.
• Chorover, J. D., Ramirez, M. D., Flor, S., Root, R. A., Mclain, J. E., Kilungo, A. P., Buxner, S. R., Abrell, L. M., & Villagomez-Marquez, N. (2020, October). Pesticides detected in roof-harvested rainwater in rural and urban Arizona communities. Emerging Contaminants Summit. Westminster, Colorado (Virtual).
• Henson, C., Villagomez-Marquez, N., Abrell, L. M., Buxner, S. R., Kilungo, A. P., Mclain, J. E., Root, R. A., Sandoval, F., & Ramirez, M. D. (2020, October). Per- polyfluoroalkyl substances in roof-harvested rainwater. Emerging Contaminants Summit. Westminster, Colorado (Virtual).
• Henson, C., Villagomez-Marquez, N., Abrell, L. M., Buxner, S. R., Kilungo, A. P., Mclain, J. E., Root, R. A., Sandoval, F., & Ramirez, M. D. (2020, October). Per-polyfluoroalkyl substances in roof-harvested rainwater. Emerging Contaminants Summit. Westminster, Colorado (Virtual).
• Mathur, S., Abrell, L. M., Villagomez-Marquez, N., Palawat, K., Ramirez, M. D., Mclain, J. E., Root, R. A., Buxner, S. R., Kilungo, A. P., & Flor, S. (2020, August). What's in your rainwater? Inorganic and organic contaminants measured in roof-harvested rainwater. KEYS Research Internship Showcase. Tucson, Arizona (Virtual): Keep Engaging Youth in Science Internship Program.
• Moses, A. J., Moses, A. J., Moses, A. J., Abrell, L. M., Abrell, L. M., Abrell, L. M., Buxner, S. R., Buxner, S. R., Buxner, S. R., Kilungo, A. P., Kilungo, A. P., Kilungo, A. P., Mclain, J. E., Mclain, J. E., Mclain, J. E., Obergh, V., Obergh, V., Obergh, V., Root, R. A., , Root, R. A., et al. (2020, November). Indicator organism presence in urban and rural Arizona community garden soils watered with harvested rainwater. ASA-CSSA-SSSA International Annual Meetings. Virtual: Agronomy Societies.
• Pier, N., Hall, G., Ellsworth, P. C., Abrell, L. M., & Diaz, D. (2019, August). Blister Beetles of Arizona. University of Arizona Cooperative Extension Annual Conference. Tucson Arizona: Cooperative Extension - University of Arizona.
• Dontsova, K. M., Taylor, S., Hunt, E., Troya, D., Abrell, L. M., Hyatt, L., & Qin, C. (2018, August). Outdoor Photolysis and Dissolution of Insensitive Munition Formulation IMX-101 and IMX-104: Transformation Pathway and Mechanism Study. 256th American Chemical Society National Meeting & Exposition. Boston, MA: American Chemical Society.
• Fitzsimmons, K., Meixner, T., Abrell, L. M., & Mclain, J. E. (2018, February). Might recycled water solve the problem of toxin-producing algae?. University of Arizona Water Resources Research Center 2018 Annual Conference. Tucson, Arizona: University of Arizona Water Resources Research Center.
• Moses, A., Moses, A., Solis-Leon, J., Solis-Leon, J., Abrell, L. M., Abrell, L. M., Buxner, S. R., Buxner, S. R., Kilungo, A. P., Kilungo, A. P., Mclain, J. E., Mclain, J. E., Root, R. A., Root, R. A., Sandoval, F., Sandoval, F., Ramirez, M. D., & Ramirez, M. D. (2018, March). The volunteer army: a review of ethical concerns in citizen science. Science of the Environment Earth Day Poster Presentation. Tucson, Arizona: University of Arizona Department of Soil, Water and Environmental Science.
• Ramirez, M. D., Sandoval, F., Root, R. A., Mclain, J. E., Kilungo, A. P., Buxner, S. R., Abrell, L. M., Montijo, F., & Villagomez-Marquez, N. (2018, March). Investigating emerging organic contaminants in harvested rainwater via co-created citizen science: what is in your rainwater?. Science of the Environment Earth Day Poster Presentation. Tucson, Arizona: University of Arizona Department of Soil, Water and Environmental Science.
• Ramirez, M. D., Sandoval, F., Root, R. A., Mclain, J. E., Kilungo, A. P., Buxner, S. R., Abrell, L. M., Montijo, F., & Villagómez-Márquez, N. (2018, April). Investigating emerging organic contaminants in harvested rainwater via Co-Created Citizen Science: What is in your rainwater?. SWESx. The University of Arizona.
• Ramirez, M. D., Sandoval, F., Root, R. A., Mclain, J. E., Kilungo, A. P., Buxner, S. R., Abrell, L. M., Solis, J., & Moses, A. (2018, April). The Volunteer Army: A Review of Ethical Concerns in Citizen Science.. SWESx. University of Arizona.
• Sandoval, F., Root, R. A., Ramirez, M. D., Mclain, J. E., Kilungo, A. P., Buxner, S. R., Abrell, L. M., Davis, L., Kaufmann, D., & Sandhaus, S. (2018, May). Advancing Informal Environmental Health STEM Learning through Co-Created Citizen Science. Teaching and Learning in the Food-Energy-Water Nexus: Toward a National and Collaborative for Food, Energy and Water Systems (NC-FEW).. Washington, DC.
• Ornelas, Y., Reynolds, K. A., Abrell, L. M., Grigera, S., & Beamer, P. (2014, October). Microbial and inorganic contamination in private wells along the Santa Cruz River, Arizona. International Society of Exposure Science. Cincinnati, OH.
• Walston, S., Mclain, J. E., Abrell, L. M., Gerrity, D., & Rock, C. M. (2013, May). Does increasing solids retention time in the wastewater treatment process affect the persistence of antibiotic resistance genes?. 86th Annual AZWater Conference. Glendale, Arizona: AZWater.
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  Poster presentation of Master's Research.