Eric A Betterton

Interests

Research

AerosolsMy research group studied aerosols associated with mining activity such as wind-blown dust from mine tailings impoundments and smelting process emissions. We operate aerosol sampling equipment including MOUDIs and an SMPS analyzer at two field sites contaminated with arsenic and lead: the Iron King mine tailings near Dewey-Humboldt, Arizona; and the ASARCO copper mine and smelter in Hayden, Arizona (Journal of Water Air and Soil Pollution, 221, 145-157, 2011).Pollution PreventionI also served as PI on an EPA Pollution Prevention (P2) grant. Together with a local non-profit, the Sonora Environmental Research Institute (SERI), we monitored metals in PM10 samples obtained in the south side of Tucson, and trained promotoras (community health workers) to visit small businesses and to encourage them to lower emissions of air toxics, and to reduce water use.Solar EnergyWe developed forecasting capability for direct normal solar insolation using the Weather Research Forecast model; and we are examining the effects of atmospheric aerosols on solar radiation received at the surface using a high-resolution spectrophotometer to make daily observations. Work on a solar concentrator/photovoltaic array was completed in 2010. A 2-m diameter mirror was assembled, fitted to a solar tracker, and installed and tested at a Raytheon facility near the airport. The project was largely supported by Science Foundation Arizona.Air QualityThere is great interest in better understanding the factors affecting air quality in the Great Lakes region because of the long, ongoing history of ozone exceedances in this densely populated part of the country. We analyzed airplane data acquired during the 10-year LADCO project to address some fundamental questions such as: What are the concentrations and diurnal patterns of ozone and ozone precursor compounds over the lake; and is ozone formation over Lake Michigan VOC-limited or NOx-limited?Since 2019, my group in Tucson has analyzed over ten thousand air samples for volatile organic carbon compounds which are precursors for ozone formation: University of Arizona VOC-NOx Presentation 2021 Minutes. https://webcms.pima.gov/cms/One.aspx?portalId=169&pageId=64905

Teaching

ATMO 170A. Introduction to Weather and ClimateThis is a descriptive introduction to the science of weather processes and climate, including hurricanes, tornadoes, lightning, the development of cold fronts and winter storms, clouds, rain and snow, weather forecasting and the wind systems of the world. Special emphasis will be given to natural phenomena which have strong impacts on human activities including El Nino, global warming, ozone depletion, and air pollution. The fundamental importance of physics, chemistry, and mathematics to atmospheric science will be stressed. The course is taught at the level of Meteorology Today by Ahrens.ATMO 436A/536A. Fundamentals of the Atmospheric SciencesThis is the entry-level quantitative course in atmospheric sciences where students will utilize their previously acquired skills in calculus, differential equations, physics and chemistry. The course broadly covers fundamental topics in the atmospheric sciences, including atmospheric thermodynamics, atmospheric dynamics, cloud physics, solar radiation, composition of the atmosphere, atmospheric chemistry, and climate. The course is taught at the level of Atmospheric Science by Wallace and Hobbs.ATMO 451A/551A. Physical Meteorology IThis is a quantitative course in atmospheric physics that includes the composition and chemistry of the atmosphere, kinetic theory, the mechanics of ideal and real fluids, aerosol mechanics, atmospheric radiation, scattering, radiative transfer, atmospheric optics, cloud physics, and atmospheric electricity. The course is taught at the level of Fundamentals of Atmospheric Physics by Salby.ATMO 469a/569a. Air Pollution I: GasesThis is a quantitative introduction to the chemistry and physics of the troposphere and stratosphere. A strong background in chemistry, mathematics and physics is expected. Topics include natural biogeochemical cycles; atmospheric photochemistry; stratospheric ozone; urban ozone, particulate matter; atmospheric visibility; acid deposition; air pollution meteorology; Gaussian plume models; photochemical models; air quality regulations. The course is taught at the level of Atmospheric Chemistry and Physics by Seinfeld and Pandis.ATMO 469b/569b. Air Pollution II: AerosolsThis course presents a quantitative introduction to the chemistry and physics of atmospheric aerosols (airborne particulate matter). Topics include aerosol sources and sinks; basic aerosol properties; single aerosol mechanics; aerosol population dynamics; atmospheric aerosol optics; aerosols and climate; aerosols and health; regional haze; aerosol measurement techniques.

Courses

Scholarly Contributions

Journals/Publications

• Betterton, E. A., Rine, K., Almusawi, R., O’Brien‑Metzger, R., Ramirez‑Andreotta, M., & Sáez, E. (2021). Outdoor/Indoor Contaminant Transport by Atmospheric Dust and Aerosol at an Active Smelter Site. Water Air and Soil Pollution, 232, 226. doi:https://doi.org/10.1007/s11270-021-05168-2
• Foley, T. A., & Betterton, E. A. (2019). Nitrogen dry deposition to Lake Superior and Lake Michigan. Journal of Great Lakes Research, 45(2), 224-239.
• Betterton, E. A., Gil-Loaiza, J., Field, J. P., White, S. A., Csavina, J., Felix Villar, O., Sáez, E., & Maier, R. M. (2018). Dust Reduction from Mine Tailings following Compost-Assisted Phytostabilization. Environmental Science and Technology, 52(10), 5851-5858.
• Kim, C. K., Holmgren, W. F., Stovern, M., & Betterton, E. A. (2016). Toward Improved Solar Irradiance Forecasts: Comparison of Downwelling Surface Shortwave Radiation in Arizona Derived from Satellite with the Gridded Datasets. PURE AND APPLIED GEOPHYSICS, 173(8), 2929-2943.
• Kim, C. K., Holmgren, W. F., Stovern, M., & Betterton, E. A. (2016). Toward Improved Solar Irradiance Forecasts: Derivation of Downwelling Surface Shortwave Radiation in Arizona from Satellite. PURE AND APPLIED GEOPHYSICS, 173(7), 2535-2553.
• Kim, C. K., Leuthold, M., Holmgren, W. F., Cronin, A. D., & Betterton, E. A. (2016). Toward Improved Solar Irradiance Forecasts: a Simulation of Deep Planetary Boundary Layer with Scattered Clouds Using the Weather Research and Forecasting Model. PURE AND APPLIED GEOPHYSICS, 173(2), 637-655.
• Stovern, M., Guzman, H., Rine, K. P., Felix, O., King, M., Ela, W. P., Betterton, E. A., & Saez, A. E. (2016). Windblown Dust Deposition Forecasting and Spread of Contamination around Mine Tailings. ATMOSPHERE, 7(2).
• Youn, J., Csavina, J., Rine, K. P., Shingler, T., Taylor, M. P., Saez, A. E., Betterton, E. A., & Sorooshian, A. (2016). Hygroscopic Properties and Respiratory System Deposition Behavior of Particulate Matter Emitted By Mining and Smelting Operations. ENVIRONMENTAL SCIENCE & TECHNOLOGY, 50(21), 11706-11713.
• Betterton, E., Herman, B., Krider, E. P., & Riley, J. J. (2015). TRIBUTE TO WILLIAM D. SELLERS (1928-2014). BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 96(1), 135-136.
• Felix, O. I., Csavina, J., Field, J., Rine, K. P., Saez, A. E., & Betterton, E. A. (2015). Use of lead isotopes to identify sources of metal and metalloid contaminants in atmospheric aerosol from mining operations. CHEMOSPHERE, 122, 219-226.
• Ramirez, D. M., Ramirez-Andreotta, M. D., Vea, L., Estrella-Sanchez, R., Wolf, A., Kilungo, A., Spitz, A. H., & Betterton, E. A. (2015). Pollution Prevention through Peer Education: A Community Health Worker and Small and Home-Based Business Initiative on the Arizona-Sonora Border. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, 12(9), 11209-11226.
• Stovern, M., Rine, K. P., Russell, M. R., Felix, O., King, M., Saez, A. E., & Betterton, E. A. (2015). Development of a dust deposition forecasting model for mine tailings impoundments using in situ observations and particle transport simulations. AEOLIAN RESEARCH, 18, 155-167.
• Csavina, J., Field, J., Felix, O., Corral-Avitia, A. Y., Eduardo, S. A., & Betterton, E. A. (2014). Effect of wind speed and relative humidity on atmospheric dust concentrations in semi-arid climates. SCIENCE OF THE TOTAL ENVIRONMENT, 487, 82-90.
• Csavina, J., Taylor, M. P., Felix, O., Rine, K. P., Saez, A. E., & Betterton, E. A. (2014). Size-resolved dust and aerosol contaminants associated with copper and lead smelting emissions: Implications for emission management and human health. SCIENCE OF THE TOTAL ENVIRONMENT, 493, 750-756.
• Holmgren, W. F., Lorenzo, A. T., Leuthold, M., Kim, C. K., Cronin, A. D., & Betterton, E. A. (2014). An Operational, Real-Time Forecasting System for 250 MW of PV Power Using NWP, Satellite, and DG Production data. 2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), 80-84.
• Lorenzo, A. T., Holmgren, W. F., Leuthold, M., Kim, C. K., Cronin, A. D., & Betterton, E. A. (2014). Short-Term PV Power Forecasts Based on a Real-Time Irradiance Monitoring Network. 2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC), 75-79.
• Prabhakar, G., Betterton, E. A., Conant, W., & Herman, B. M. (2014). Effect of Urban Growth on Aerosol Optical Depth-Tucson, Arizona, 35 Years Later. JOURNAL OF APPLIED METEOROLOGY AND CLIMATOLOGY, 53(8), 1876-1885.
• Prabhakar, G., Sorooshian, A., Toffol, E., Arellano, A. F., & Betterton, E. A. (2014). Spatiotemporal distribution of airborne particulate metals and metalloids in a populated arid region. ATMOSPHERIC ENVIRONMENT, 92, 339-347.
• Stovern, M., Felix, O., Csavina, J., Rine, K. P., Russell, M. R., Jones, R. M., King, M., Betterton, E. A., & Saez, A. E. (2014). Simulation of windblown dust transport from a mine tailings impoundment using a computational fluid dynamics model. AEOLIAN RESEARCH, 14, 75-83.
• Betterton, E., Sorooshian, A., Csavina, J., Shingler, T., Dey, S., Brechtel, F. J., Sáez, A. E., & Betterton, E. A. (2012). Hygroscopic and chemical properties of aerosols collected near a copper smelter: implications for public and environmental health. Environmental science & technology, 46(17).
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  Particulate matter emissions near active copper smelters and mine tailings in the southwestern United States pose a potential threat to nearby environments owing to toxic species that can be inhaled and deposited in various regions of the body depending on the composition and size of the particles, which are linked by particle hygroscopic properties. This study reports the first simultaneous measurements of size-resolved chemical and hygroscopic properties of particles next to an active copper smelter and mine tailings by the towns of Hayden and Winkelman in southern Arizona. Size-resolved particulate matter samples were examined with inductively coupled plasma mass spectrometry, ion chromatography, and a humidified tandem differential mobility analyzer. Aerosol particles collected at the measurement site are enriched in metals and metalloids (e.g., arsenic, lead, and cadmium) and water-uptake measurements of aqueous extracts of collected samples indicate that the particle diameter range of particles most enriched with these species (0.18-0.55 μm) overlaps with the most hygroscopic mode at a relative humidity of 90% (0.10-0.32 μm). These measurements have implications for public health, microphysical effects of aerosols, and regional impacts owing to the transport and deposition of contaminated aerosol particles.
• Betterton, E., Csavina, J., Landázuri, A., Wonaschütz, A., Rine, K., Rheinheimer, P., Barbaris, B., Conant, W., Sáez, A. E., & Betterton, E. A. (2011). Metal and Metalloid Contaminants in Atmospheric Aerosols from Mining Operations. Water, air, and soil pollution, 221(1-4).
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  Mining operations are potential sources of airborne metal and metalloid contaminants through both direct smelter emissions and wind erosion of mine tailings. The warmer, drier conditions predicted for the Southwestern US by climate models may make contaminated atmospheric dust and aerosols increasingly important, with potential deleterious effects on human health and ecology. Fine particulates such as those resulting from smelting operations may disperse more readily into the environment than coarser tailings dust. Fine particles also penetrate more deeply into the human respiratory system, and may become more bioavailable due to their high specific surface area. In this work, we report the size-fractionated chemical characterization of atmospheric aerosols sampled over a period of a year near an active mining and smelting site in Arizona. Aerosols were characterized with a 10-stage (0.054 to 18 μm aerodynamic diameter) multiple orifice uniform deposit impactor (MOUDI), a scanning mobility particle sizer (SMPS), and a total suspended particulate (TSP) collector. The MOUDI results show that arsenic and lead concentrations follow a bimodal distribution, with maxima centered at approximately 0.3 and 7.0 μm diameter. We hypothesize that the sub-micron arsenic and lead are the product of condensation and coagulation of smelting vapors. In the coarse size, contaminants are thought to originate as aeolian dust from mine tailings and other sources. Observation of ultrafine particle number concentration (SMPS) show the highest readings when the wind comes from the general direction of the smelting operations site.
• Foley, T., Betterton, E. A., Jacko, P. R., & Hillery, J. (2011). Lake Michigan air quality: The 1994-2003 LADCO Aircraft Project (LAP). Atmospheric Environment, 45(18), 3192-3202.
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  Abstract: The goal of the 1994 to 2003 LADCO Airplane Project (LAP) was to study ozone formation over Lake Michigan so that equitable regional control strategies could be devised. This paper for the first time documents LAP in the peer-reviewed literature. Dye et al. (1995) found that the atmosphere over Lake Michigan is stable in the summer due to the airwater temperature difference, which creates an efficient reaction chamber for ozone formation. They also hypothesize that the southwest winds characteristic of ozone-conducive conditions transport ozone further north over the lake before it crosses the shoreline onto land. This statistical analysis of LAP data support the hypothesis of Dye et al. Below 200 m above the lake, ozone formation is VOC-limited in the morning and becomes NOx limited in the afternoon. Above 200 m, ozone formation is NOx-limited throughout the day. The onshore NOx and VOC diurnal cycles peak during the early morning rush hour and are clearly linked to traffic patterns. Over the lake, VOC and NOy concentrations peak during the mid-morning rather than the early morning, supporting the hypothesis that the land breeze transports VOC and NOy over the lake. The diurnal NOx pattern over Lake Michigan is less clearly defined than the VOC pattern possibly as a result of emissions from five coal-burning power plants located on the Lake Michigan shoreline. Using a "photochemical clock" model, we estimate the climatological average hydroxyl radical concentration over the lake to be (9.43 ± 5.88) × 106 molecule cm-3 near Chicago and (8.43 ± 3.68) × 106 molecule cm-3 near Milwaukee. © 2011 Elsevier Ltd.
• Betterton, E. A., Lowry, J., Ingamells, R., & Venner, B. (2010). Kinetics and mechanism of the reaction of sodium azide with hypochlorite in aqueous solution. Journal of Hazardous Materials, 182(1-3), 716-722.
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  PMID: 20667654;Abstract: Production of toxic sodium azide (NaN3) surged worldwide over the past two decades to meet the demand for automobile air bag inflator propellant. Industrial activity and the return of millions of inflators to automobile recycling facilities are leading to increasing release of NaN3 to the environment so there is considerable interest in learning more about its environmental fate. Water soluble NaN3 could conceivably be found in drinking water supplies so here we describe the kinetics and mechanism of the reaction of azide with hypochlorite, which is often used in water treatment plants. The reaction stoichiometry is: HOCl+2N3-=3N2+Cl-+OH-, and proceeds by a key intermediate chlorine azide, ClN3, which subsequently decomposes by reaction with a second azide molecule in the rate determining step: ClN3+N3-→3N2+Cl- (k=0.52±0.04M-1s-1, 25°C, μ=0.1M). We estimate that the half-life of azide would be ≈15s at the point of chlorination in a water treatment plant and ≈24 days at some point downstream where only residual chlorine remains. Hypochlorite is not recommended for treatment of concentrated azide waste due to formation of the toxic chlorine azide intermediate under acidic conditions and the slow kinetics under basic conditions. © 2010 Elsevier B.V.
• Betterton, E., Gao, S., Rupp, E., Bell, S., Willinger, M., Foley, T., Barbaris, B., Sáez, A. E., Arnold, R. G., & Betterton, E. A. (2008). Mixed redox catalytic destruction of chlorinated solvents in soils and groundwater. Annals of the New York Academy of Sciences, 1140.
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  A new thermocatalytic method to destroy chlorinated solvents has been developed in the laboratory and tested in a pilot field study. The method employs a conventional Pt/Rh catalyst on a ceramic honeycomb. Reactions proceed at moderate temperatures in the simultaneous presence of oxygen and a reductant (mixed redox conditions) to minimize catalyst deactivation. In the laboratory, stable operation with high conversions (above 90% at residence times shorter than 1 s) for perchloroethylene (PCE) is achieved using hydrogen as the reductant. A molar ratio of H(2)/O(2)= 2 yields maximum conversions; the temperature required to produce maximum conversions is sensitive to influent PCE concentration. When a homologous series of aliphatic alkanes is used to replace hydrogen as the reductant, the resultant mixed redox conditions also produce high PCE conversions. It appears that the dissociation energy of the C-H bond in the respective alkane molecule is a strong determinant of the activation energy, and therefore the reaction rate, for PCE conversion. This new method was employed in a pilot field study in Tucson, Arizona. The mixed redox system was operated semicontinuously for 240 days with no degradation of catalyst performance and complete destruction of PCE and trichloroethylene in a soil vapor extraction gas stream. Use of propane as the reductant significantly reduced operating costs. Mixed redox destruction of chlorinated solvents provides a potentially viable alternative to current soil and groundwater remediation technologies.
• Betterton, E., Orbay, O., Gao, S., Barbaris, B., Rupp, E., Sáez, A. E., Arnold, R. G., & Betterton, E. A. (2008). Catalytic Dechlorination of Gas-phase Perchloroethylene under Mixed Redox Conditions. Applied catalysis. B, Environmental, 79(1).
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  The validity of a new method to destroy gas-phase perchloroethylene (PCE) is demonstrated at bench scale using a fixed-bed reactor that contains a Pt/Rh catalyst. Hydrogen and oxygen were simultaneously fed to the reactor together with PCE. The conversion efficiencies of PCE were sensitive to H(2)/O(2) ratio and reactor temperature. When the temperature was >/= 400 degrees C and H(2)/O(2) was >/= 2.15, PCE conversion efficiency was maintained at >/= 90%. No catalyst deactivation was observed for over two years, using only mild, convenient regeneration procedures. It is likely that PCE reduction steps precede oxidation reactions and that the importance of oxidation lies in its elimination of intermediates that would otherwise lead to catalyst poisoning. In practice, this catalytic dechlorination method holds potential for low-cost, large-scale field operation.
• Matichuk, R., Barbaris, B., Betterton, E. A., Hori, M., Murao, N., Ohta, S., & Ward, D. (2006). A decade of aerosol and gas precursor chemical characterization at Mt. Lemmon, Arizona (1992 to 2002). Journal of the Meteorological Society of Japan, 84(4), 653-670.
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  Abstract: Aerosols (PM2.0), and associated precursor gases have been continuously monitored at Mt. Lemmon (2791 m ASL), Arizona, since September 1992. Month-long samples are collected on filters and chemically analyzed resulting in a decade-long record with over 100 data points for each species-among the longest such records currently available. The species determined include SO42-, NO3-, Cl-, NH4+, Ca2+, Mg2+, K+, Na+, elemental carbon (EC), organic carbon (OC), NH3(g), SO2(g), HCl(g) and HNO3(g). The data reveal long-term trends, seasonal variations, and correlations between species. PM2.0 (1.48 μg m-3, annual mean) is mainly comprised of SO42- (49% w/w), NH4+ (16%), EC (11%) and OC (22%). The mean SO42-/NH4+ equivalent ratio is 1:1 suggesting complete neutralization. Median PM2.0 was 1.33 μg m-3 (range = 0.17-4.32 μg m-3). Median EC was 0.14 μg m-3 (0.01-0.76), and median OC was 0.29 μg m-3 (0.03-1.33). The annual mean trends of all species, with the exception of SO42-, SO2(g), NH4+ and NH3(g), appear to be increasing, but some trends may not be statistically significant. Long-term decreasing trends in SO2(g) and SO42-, reflect source controls implemented over the past decade, whereas HNO3(g) has been increasing, possibly due to increased NOX emissions associated with population growth in the region. The associated conversion of agricultural land to urban use might be leading to a decrease in NH3(g). Annual trends for EC (5.2 ± 2.7 ng m-3 y-1) and EC/OC ((1.5 ± 0.75) × 10-2 y-1) appear to be positive and significant, but there is no significant annual OC trend. There appears to be a significant secondary source of OC, presumably derived from photoxidation of biogenic hydrocarbons. There is no significant trend in the calculated annual mean extinction coefficient but the calculated single scattering albedo (ω) may be decreasing (-1.5 ± 1.1 × 10-3 y-1), possibly caused by increasing EC associated with forest fires and/or fossil fuel combustion. Depending on the value of the critical single scattering albedo, the aerosol might already be a net absorber, or it might only become so by the end of the century if current trends continue. © 2006, Meteorological Society of Japan.
• Fowler, T. L., Bornstein, R. D., Betterton, E. A., Detwiler, A., Feingold, G., Golden, J. H., Griffith, D. A., Langerud, D. W., Pryor, S. C., & Sweeney, P. H. (2005). 85^th AMS Annual Meeting, American Meteorological Society - Combined Preprints: Foreword. 85th AMS Annual Meeting, American Meteorological Society - Combined Preprints, xii-xv.
• Orlando, J. J., Tyndall, G. S., Betterton, E. A., Lowry, J., & Stegall, S. T. (2005). Atmospheric chemistry of hydrazoic acid (HN₃): UV absorption spectrum, HO• reaction rate, and reactions of the •N₃ radical. Environmental Science and Technology, 39(6), 1632-1640.
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  PMID: 15819219;Abstract: Processes related to the tropospheric lifetime and fate of hydrazoic acid, HN3, have been studied. The ultraviolet absorption spectrum of HN3 is shown to possess a maximum near 262 nm with a tail extending to at least 360 nm. The photolysis quantum yield for HN3 is shown to be ≈1 at 351 nm. Using the measured spectrum and assuming unity quantum yield throughout the actinic region, a diurnally averaged photolysis lifetime near the earth's surface of 2-3 days is estimated. Using a relative rate method, the rate coefficient for reaction of HO• with HN3 was found to be (3.9 ± 0.8) × 10-12 cm3 molecule-1 s-1, substantially larger than the only previous measurement. The atmospheric HN3 lifetime with respect to HO• oxidation is thus about 2-3 days, assuming a diurnally averaged [HO•] of 106 molecule cm-3. Reactions of •N3, the product of the reaction of HO• with HN3, were studied in an environmental chamber using an FTIR spectrometer for end-product analysis. The •N 3 radical reacts efficiently with NO, producing N2O with 100% yield. Reaction of •N3 with NO2 appears to generate both NO and N2O, although the rate coefficient for this reaction is slower than that for reaction with NO. No evidence for reaction of •N3 with CO was observed, in contrast to previous literature data. Reaction of •N3 with O2 was found to be extremely slow, k < 6 × 10-20 cm3 molecule -1 s-1, although this upper limit does not necessarily rule out its occurrence in the atmosphere. Finally, the rate coefficient for reaction of Cl• with HN3 was measured using a relative rate method, k = (1.0 ± 0.2) × 10-12 cm3 molecule-1 s-1. © 2005 American Chemical Society.
• Betterton, E. A. (2003). Environmental Fate of Sodium Azide Derived from Automobile Airbags. Critical Reviews in Environmental Science and Technology, 33(4), 423-458.
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  Abstract: The environmental fate of sodium azide (NaN3) is of considerable interest given the recent surge in production to satisfy demand for automobile air bag inflators, where it serves as the principal active ingredient. Since the mid-1990s, demand for sodium azide has exceeded 5 million kg per year and most passenger vehicles sold in the United States now contain approximately 300 g (≈0.7 lb) of sodium azide. This has greatly increased the potential for accidental environmental releases and for human exposure to this highly toxic, broad-spectrum biocide. It can be argued that a new environmental threat has developed because not only are millions of kilograms of sodium azide now transported to and processed at air bag inflator factories, but also this substance is now widely distributed throughout the developed world in automobiles. Even if sodium azide were to be replaced by a more benign propellant in the future, the problem of safely disposing of large quantities of azide will remain as the vehicle fleet ages and is retired to scrap yards and shredders. Unfortunately, the environmental fate of sodium azide is unknown so it is difficult to effectively manage releases. The problem is compounded by the fact that aqueous sodium azide is readily hydrolyzed to yield hydrazoic acid (HN3), a volatile substance that partitions strongly to the gas phase.
• S., M., Eldik, R. V., L., P., Pratt, J. M., & Betterton, E. A. (2002). Five-coordination and adduct formation in Co^III-corrinoids dissecting ligand substitution into its component steps. European Journal of Inorganic Chemistry, 580-583.
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  Abstract: The equilibria between the five- and six-coordinate species of alkylcobinamide and cobalamin (base-off) have been studied using high-pressure spectroscopic techniques. The addition of a water molecule to the five-coordinate complex is accompanied by a volume decrease of 12 cm3·mol-1.
• Betterton, E. A., & Anderson, D. J. (2001). Autoxidation of N(III), S(IV), and other species in frozen solution - A possible pathway for enhanced chemical transformation in freezing systems. Journal of Atmospheric Chemistry, 40(2), 171-189.
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  Abstract: Freezing dilute aqueous solutions of certain oxidizable species such as nitrite and sulfite can promote the rate of autoxidation, instead of retarding it. Experiments show that nitrite and sulfite undergo rapid oxidation to nitrate and sulfate, respectively, in high yield (>90% under certain conditions) when their dilute (100 μM) aqueous solutions are frozen for 10-60 min. at -10 to -40°C. For example, the pseudo-second-order rate constant for nitrite autoxidation, k′, defined in d[NO3-]/dt = 2k′ [HNO2]2, reaches a maximum value of 117 ± 14 M-1s-1 at -15.5°C. This counterintuitive result is hypothesized to be the result of a freeze-concentration effect that occurs when reactants are concentrated into liquid micropockets ahead of the advancing ice front. Oxidation by hydrogen peroxide is also accelerated upon freezing. Since the yields and rates may be high compared to other competing pathways, this process may be significant where freeze/thaw cycles occur naturally, e.g., in glaciating clouds, snow packs, glaciers, and melt ponds on polar sea ice.
• Betterton, E. A. (2000). Environmental fate of sodium azide derived from automobile airbags. ACS Division of Environmental Chemistry, Preprints, 40(1), 129-130.
• Betterton, E. A., & Craig, D. (1999). Kinetics and mechanism of the reaction of azide with ozone in aqueous solution. Journal of the Air and Waste Management Association, 49(11), 1347-1354.
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  Abstract: The stoichiometry of the reaction of aqueous ozone with sodium azide was studied at pH 12 (mainly) where a yellow metastable intermediate is observed. We propose that this is hypoazidite (N3O-), analogous to hypobromite, and that it plays a central role in the azide catalyzed decompostion of ozone. The yellow intermediate is unstable in acid, in which it rapidly decomposes, generating N2 and NO2-. The rate of reaction was studied at pH 2.0-3.5, with the ionic strength at 0.6 M and temperature at 3-15 °C. The intrinsic second-order rate constants were found to be k(HN3) ≤≃400M-1sec-1 and k(N3)- = (8.7 ± 0.5) x 105 M-1sec-1 (3 °C, 0.6 M), both in agreement with the only other previous study. The rate constant at 25 °C was estimated using the following experimentally determined parameters: In k(N3) (M-1sec-1) = (5.73 ± 0.36) x 103/T (K) + (28.34 ± 1.27). The value of k(N3) - estimated in this way is (2.5 ± 0.1) x 106 M-1sec-1 at 25 °C and 0.6 M. The enthalpy of reaction (ΔH) is -48 ± 3 kJ mol-1.
• Klimowski, B. A., Becker, R., Betterton, E. A., Bruintjes, R., Clark, T. L., Hall, W. D., Orr, B. W., Kropfli, R. A., Piironen, P., Reinking, R. F., Sundie, D., & Uttal, T. (1998). The 1995 Arizona Program: Toward a Better Understanding of Winter Storm Precipitation Development in Mountainous Terrain. Bulletin of the American Meteorological Society, 79(5), 799-813.
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  Abstract: The 1995 Arizona Program was a field experiment aimed at advancing the understanding of winter storm development in a mountainous region of central Arizona. From 15 January through 15 March 1995, a wide variety of instrumentation was operated in and around the Verde Valley southwest of Flagstaff, Arizona. These instruments included two Doppler dual-polarization radars, an instrumented airplane, a lidar, microwave and infrared radiometers, an acoustic sounder, and other surface-based facilities. Twenty-nine scientists from eight institutions took part in the program. Of special interest was the interaction of topographically induced, storm-embedded gravity waves with ambient upslope flow. It is hypothesized that these waves serve to augment the upslope-forced precipitation that falls on the mountain ridges. A major thrust of the program was to compare the observations of these winter storms to those predicted with the Clark-NCAR 3D, nonhydrostatic numerical model.
• Martinez-Martinez, J., & Betterton, E. A. (1998). Input data for photochemical modeling of urban ozone in Monterrey, Mexico. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition, 18pp.
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  Abstract: This paper describes the input data used to evaluate the performance of a photochemical urban model with the environmental and geographical characteristics of the Monterrey Metropolitan Area. For the period 1993 through 1995, the Mexican ozone standard (110 ppbv) was exceeded on 63 days. This paper focuses on the application of a photochemical model to two high-ozone episodes in 1995: January 9-11 (winter episode) and July 3-5 (summer episode). Episode selection and inputs to the model were based on a review of available air quality, meteorological, and emission data. The model results show that the ozone concentrations are well-predicted for the summer period while they are underpredicted for the winter event. In addition, ozone is more sensitive to the variation of reactive hydrocarbon emissions in the winter. These results suggest that characterization of the diurnal pattern of industrial and vehicle emissions of reactive hydrocarbons needs to be improved. Also, the hourly differences in concentrations indicate that mountain-valley circulation may be a significant factor in ozone formation driven by recirculation of air pollutants. The emission inventory and ambient concentration data for Monterrey in the period 1993 through 1995 indicate that carbon monoxide emissions have decreased, while nitrogen oxides emissions remained constant. Also, these data suggest that hydrocarbon emissions may have decreased. However, the aromatic content in the reactive hydrocarbon emissions may be higher due to the recent introduction of gasoline additives.
• Zailiang, H. u., Bruintjes, R. T., & Betterton, E. A. (1998). Sensitivity of cloud droplet growth to collision and coalescence efficiencies in a parcel model. Journal of the Atmospheric Sciences, 55(15), 2502-2515.
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  Abstract: The purpose of this study is to assess the relative importance of collision and coalescence efficiencies as reported in the literature in different drop size regimes for the development of precipitation via the condensation-coalescence process. The stochastic growth of cloud droplet distributions due to collection processes is studied using a detailed microphysical parcel model. The evolution of rainwater content (LR) and the radar reflectivity factor (Z) are plotted in order to trace the progress of transfer of cloud water into rainwater and determine the importance of droplet collection in different size ranges. The results indicate that the van der Waals forces are effective in enhancing droplet collision when the droplets are small and the distributions are narrow. Wake capture is negligible for clouds forming in a continental air mass with low liquid water contents. However, it is effective when coalescence becomes the dominant growth process and rainwater content has reached high values. When nonunity coalescence efficiencies are used, the drop growth and cloud water to rainwater conversion is reduced compared to the traditional unity coalescence efficiencies used in previous modeling studies. However, the major difference between the results using nonunity and unity coalescence efficiencies is due to the extrapolation of coalescence efficiencies measured in laboratory to size domains outside the domain of the measurements.
• Betterton, E. A., & Robinson, J. L. (1997). Henry's law coefficient of hydrazoic acid. Journal of the Air and Waste Management Association, 47(11), 1216-1219.
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  Abstract: The Henry's law constant, K(H), of dilute aqueous hydrazoic acid, HN3, was determined experimentally for the first time as a function of concentration and temperature in a packed column. K(H) was found to be 12.0 ± 0.7 M atm-1 at 25 °C, μ = 0.02 M ((8.4 ± 0.5) x 10-3 kPa m3mol-1). The reaction enthalpy, ΔH, was found to be -31 ± 1 kJ mol-1. The results appear to be in good agreement with the only other published value for concentrated aqueous solutions at 30 °C.
• Martinez-Martinez, J., & Betterton, E. A. (1997). Characterization of ozone episodes in Monterrey, Mexico. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition.
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  Abstract: A study was conducted to gain a better understanding of the factors that affect the generation and transport of ozone in the Monterrey air basin. The meteorology patterns and resulting air quality conditions associated with high ozone days during 1995 in the air basin are presented and analyzed. The ambient nonmethane hydrocarbon data collected in the northeastern region during January 1995 are examined.
• Philippin, S., & Betterton, E. A. (1997). Cloud condensation nuclei concentrations in Southern Arizona: Instrumentation and early observations. Atmospheric Research, 43(3), 263-275.
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  Abstract: During an ongoing study to measure cloud condensation nuclei (CCN) concentrations, a new automated thermal diffusion CCN counter was operated during the months January through June 1994 near the summit of Mt. Lemmon in the Catalina Mountains at about 2700 m elevation. The instrument records data continuously at 5-minute intervals 24 hours a day. The status of the instrument and the data are monitored remotely by telephone modem. For the 123-day, continuous study the average CCN concentration was found to range between a few tens and a few hundred nuclei per cm3 at supersaturations between 0.3 and 0.7%. Diurnal variations were observed, as well as other possible influences, such as wind speed, wind direction and mixing depth. At a constant supersaturation of 0.35% the CCN concentration is typically on the order of 50 to 150 nuclei per cm3. A description of the instrumentation and early observations are presented and discussed. © 1997 Elsevier Science B.V.
• Young, A. T., Betterton, E. A., & Saldivar, L. (1997). Photochemical box model for Mexico City. Atmosfera, 10(4), 161-178.
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  Abstract: A multi-level, photochemical box model has been developed for the Mexico City metropolitan area (MCMA). A combination of in situ measurements and emission inventory estimates was used to obtain estimates of hydrocarbon speciation and emissions as well as NOx emissions. Preliminary results indicate that certain emissions estimates of NOx may be too high by a factor of two. This could cause the calculated, ozone isopleths to indicate that atmospheric O3 production in the MCMA could be hydrocarbon-limited. Hydrocarbon and/or NOx control strategies should not be implemented before a reliable emissions inventory is available.
• Barbaris, B., & Betterton, E. A. (1996). Initial snow chemistry survey of the Mogollon Rim in Arizona. Atmospheric Environment, 30(17), 3093-3103.
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  Abstract: Fresh snowpack samples collected from high-elevation forests of north-central Arizona during late winter/early spring 1992-1994 were analyzed by ion chromatography and by instrumental neutron activation. Eleven major ions, including the organic species acetate and formate, and twenty-eight elements were determined. The results indicate a relatively pristine snowpack-most samples exhibited low ionic strengths (20 ± 15 μeq l-1) and moderate pH (range 4.9-5.7, mean 5.4). Typical snow-producing storms moved northeast under the influence of southwesterly how of marine air. Northwesterly winds associated with a cutoff low pressure system centered over southern Utah on 31 January and 1 February 1993 brought snowfall with increased chemical loading. The snowpack was apparently enriched with Zn, As, Sb, and Cu when compared to regional soils. Regional source emissions (smelters, metropolitan Phoenix) may have influenced the snow chemistry but their impact appears to be minimal. These apparent trace metal enrichments are similar to those found in precipitation in remote and rural locations worldwide.
• Johnson, B. J., Betterton, E. A., & Craig, D. (1996). Henry's Law coefficients of formic and acetic acids. Journal of Atmospheric Chemistry, 24(2), 113-119.
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  Abstract: The Henry's law constants, K(H), Of dilute aqueous formic and acetic acids were determined experimentally as a function of concentration and temperature using a new counterflow packed-column technique. K(H) was found to be (8.91 ± 1.3) x 103 and (4.1 ± 0.4) x 103 M atm-1 at 25°C for HCOOH and CH3COOH, respectively. The reaction enthalpies, ΔH, were found to be -51 ± 2 kJ mol-1 and -52 ± 1 kJ mol-1 formic and acetic acid, respectively. These are in good agreement for with calculated thermochemical values. Whereas the K(H) values are in reasonably good agreement with certain other experimentally determined values, K(H) (HCOOH) is two to three times higher than calculated thermochemical values while K(H) (CH3COOH) is lower than the two calculated values. The 'best' experimental values appear to be (11 ± 2) x 103 M atm-1 and (7 ± 3) x 103 M atm-1 for HCOOH and CH3COOH, respectively.
• Martinez-Martinez, J., & Betterton, E. A. (1996). Monterrey, Mexico, ozone study: air quality measurements. Proceedings of the Air & Waste Management Association's Annual Meeting & Exhibition, 16pp.
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  Abstract: The Monterrey Metropolitan Area (MMA) of Mexico has often experienced episodes with ozone concentration higher than Mexican ambient air quality standard (110 ppb). MMA is one of the most rapidly growing industrial and urban areas in the north of Mexico. This paper describes aspects related to field measurements that will be used to evaluate a photochemical urban model with the environmental and geographical characteristics of Monterrey. The model employing the Carbon Bond Mechanism IV is being developed with a hybrid method for solving the stiff ordinary differential equations. Data analysis of the field measurements is used to characterize prevailing conditions in the behavior of the air quality levels. Also, diagnostic activities provide better bases to estimate reasonable and consistent global inventories. The results provide information for testing air quality models and to establish a foundation for future studies and control strategies. Measurements over the study region consist of: (a) surface air quality data (ozone, nitrogen oxides, carbon monoxide, temperature, wind speed, and wind direction) obtained by five existing monitoring stations operating from 1992, (b) meteorological data (temperature, pressure, and relative humidity) measured by state stations, (c) emissions data measured (carbon monoxide and hydrocarbons) in vehicle exhaust pipes from September 1991 to April 1992.
• Betterton, E., Cao, Y., Conklin, M., & Betterton, E. A. (1995). Competitive complexation of trace metals with dissolved humic acid. Environmental health perspectives, 103 Suppl 1.
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  In this study we investigated the effects of competing trace metals and Ca2+ on Cd(II), Pb(II), and Cu(II) complexation by humic acid extracted from groundwater in Orange County, California. Two types of titration experiments were conducted, those using a single metal and those in which the humic acid had been preequilibrated with a competing metal (either a trace metal or Ca2+). The labile metal concentration in the titration was determined by differential pulse polarography (DPP). Results show the different effects of competing trace metal ions and the effect of Ca2+. Both trace metals and Ca2+ do not compete effectively with Cd(II) complexation. While no effects of Cu(II) on Pb(II) complexation were observed, the presence of Cd(II) appeared to slightly enhance the binding between Pb(II) and humic acid. The addition of Pb(II) decreased the amount of Cu(II) complexation, but Cd(II) caused a slight increase at the lower concentrations. Calcium, however, decreased the amount of complexation for all three metals. Results indicate that the metals are not necessarily competing for the same sites. Conformational changes that occur when trace metals bind to the different sites may cause this competing or enhanced effect. Since Ca(II) is introduced at two orders of magnitude higher in concentration than the trace metals, it can outcompete the trace metal for sites where electrostatic interactions dominate. The results indicate that in groundwater situations, where more than one metal is present, the effect of other metals must be considered in predicting metal speciation.
• Cao, Y., Conklin, M., & Betterton, E. (1995). Competitive complexation of trace metals with dissolved humic acid. Environmental Health Perspectives, 103(SUPPL. 1), 29-32.
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  PMID: 7621794;PMCID: PMC1519323;Abstract: In this study we investigated the effects of competing trace metals and Ca2+ on Cd(II), Pb(II), and Cu(II) complexation by humic acid extracted from groundwater in Orange County, California. Two types of titration experiments were conducted, those using a single metal and those in which the humic acid had been preequilibrated with a competing metal (either a trace metal or Ca2+. The labile metal concentration in the titration was determined by differential pulse polarography (DPP). Results show the different effects of competing trace metal ions and the effect of Ca2+. Both trace metals and Ca2+ do not compete effectively with Cd(II) complexation. While no effects of Cu(II) on Pb(II) complexation were observed, the presence of Cd(II) appeared to slightly enhance the binding between Pb(II) and humic acid. The addition of Pb(II) decreased the amount of Cu(II) complexation, but Cd(II) caused a slight increase at the lower concentrations. Calcium, however, decreased the amount of complexation for all three metals. Results indicate that the metals are not necessarily competing for the same sites. Conformational changes that occur when trace metals bind to the different sites may cause this competing or enchanced effect. Since Ca(II) is introduced at two orders of magnitude higher in concentration than the trace metals, it can outcompete the trace metal for sites where electrostatic interactions dominate. The results indicate that in groundwater situations, where more than one metal is present, the effect of other metals must be considered in predicting metal speciation.
• Betterton, E. A. (1993). On the pH-dependent formation constants of iron(III)-sulfur(IV) transient complexes. Journal of Atmospheric Chemistry, 17(4), 307-324.
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  Abstract: An experimental study is described of Fe(III)-S(IV) formation constants measured as a function of pH (1-3), ionic strength (0.2-0.5 M) and [Fe(III)](T) (2.5-5.0 x 10-4 M) using a continuous-flow spectrophotometric technique to make observations 160 ms after mixing. Preliminary experiments using pulse-accelerated-flow (PAF) spectrophotometry to measure rate constants on a microsecond timescale are also described. The conditional formation constant at 25°C can be modeled with the following equation: K(app) = α1α4K7 + α0α4K8, where α0 = [Fe3+]/[Fe(III)](T), α1 = [FeOH2+]/[Fe(III)](T), α4 = [HSO3-]/[S(IV)(T)], K7 = 8.5 x 102 M-1, and K8 = 5.5 x 101 M-1. K7 and K8 can be interpreted as intrinsic constants for the coordination of HSO3- by FeOH2+ and Fe3+, respectively, but until further evidence is obtained they should be regarded as fitting constants. PAF spectrophotometry showed that the initial reaction of Fe(III) with S(IV) (pH 2.0) is characterized by a second-order rate constant of ≃ 4 x 106 M-1 s-1 which is comparable to rate of reaction of FeOH2+ with SO42-. However, the PAF results should be regarded as preliminary since unexpected features in the initial data indicate that the reaction may be more complex than expected.
• Betterton, E. A. (1992). Oxidation of alkyl sulfides by aqueous peroxymonosulfate. Environmental Science and Technology, 26(3), 527-532.
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  Abstract: The kinetics and mechanism of the oxidation of the alkyl sulfides dimethyl sulfide (DMS) and diethyl sulfide (DES) by peroxymonosulfate (HSO5-) in aqueous solution were studied as a function of pH, temperature, and ionic strength. The rate law was found to be -d[R2S]/dt = k1[R2S][HSO5-] + k2[R2S][SO52-], where k1(DMS) = 0.13 ± 0.09 M-1 s-1, k2(DMS) = 29.8 ± 0.08 M-1 s-1, k1(DES) = 0.29 ± 0.01 M-1 s-1, and k2(DES) = 11.1 ± 1.0 M-1 s-1 (25 °C; ionic strength, 0.2 M). The activation parameters for DMS and DES, respectively, are ΔH‡k1 = 51.3 ± 0.5 and 40.7 ± 5.9 kJ mol-1, ΔS‡k1 = -87.0 ± 0.1 and -119 ± 20 J K-1 mol-1, ΔH‡k2 = 43.5 ± 1.9 and 18.5 ± 3.3 kJ mol-1, and ΔS‡k2 = -70 ± 7 and -164 ± 18 J K-1 mol-1. Dimethyl sulfoxide, dimethyl sulfone, diethyl sulfoxide, and diethyl sulfone were identified as reaction products. A comparison of the relative rates of oxidation of DMS and DES by HSO5-, H2O2, and O3 shows that HSO5- may be a more important aqueous sink for the alkyl sulfides than H2O2. O3 is, however, likely to be the dominant aqueous oxidant under conditions that could be expected in remote marine clouds. © 1992 American Chemical Society.
• Betterton, E. A. (1991). Acid rain experiment and construction of a simple turbidity meter. Journal of Chemical Education, 68(3), 254-256.
• Betterton, E. A., & Hoffmann, M. R. (1990). Kinetics and mechanism of the oxidation of aqueous hydrogen sulfide by peroxymonosulfate. Environmental Science and Technology, 24(12), 1819-1824.
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  Abstract: The stoichiometry and mechanism of the oxidation of aqueous S(-II) by HSO5- is similar to the oxidation of S(-II) by H2O2, but the rate of oxidation by HSO5- is 3-4 orders of magnitude faster than the corresponding reaction with H2O2. A two-term rate law of the following form is found to be valid for the pH range of 2.0-6.3: -d[S(-II)]/dt = k1[H2S][HSO5-] + k2K(a)1[H2S][HSO5-]/[H+], where k1 = 1.98 x 101 M-1 s-1, k2 = 1.22 x 104 M-1 s-1, and K(a)1 = [H+][HS-]/[H2S] = 2.84 x 10-8 M at 4.9 °C, μ = 0.2 M, and [S(-II)] = [H2S] + [HS-] + [S2-]. At high pH and high [HSO5-]/[S(-II)] ratios SO42- and H+ formation are favored, whereas at low pH and low [HSO5-]/[S(-II)] ratios elemental sulfur (S8) is favored as the principal reaction product. Peroxymonosulfate is a monosubstituted derivative of hydrogen peroxide that is thermodynamically more powerful as an oxidant than H2O2 and kinetically more reactive. These properties make HSO5- a potentially important oxidant in natural systems such as remote tropospheric clouds and also a viable alternative to H2O2 for the control of malodorous sulfur compounds and for the control of sulfide-induced corrosion in concrete sewers.
• Betterton, E. A., & Hoffmann, M. R. (1989). Oxidation of aqueous hydrogen sulfide by peroxymonosulfate. Proceedings - A&WMA Annual Meeting, 6.
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  Abstract: This paper summarizes the results of an experimental investigation of the stoichiometry and kinetics of the oxidation of aqueous hydrogen sulfide by the inorganic peroxide, peroxymonosulfate (HSO5-). Peroxymonosulfate is a powerful oxidant1 (E0 = +1.82 V) that is commercially available as a free-flowing powder known by the trade name Oxone. The latter is a triple salt with the composition 2KHSO5·KHSO4·K2SO4. It is shown that peroxymonosulfate oxidizes aqueous H2S 3-4 orders of magnitude faster than H2O2 at a given pH, and therefore in applications where the rate of oxidation of H2S is of prime concern or where high concentrations of oxidant cannot be tolerated peroxymonosulfate may be an attractive alternative to H2O2. However comparison of eq 3 with eq 5, and eq 4 with eq 6 shows that the use of peroxymonsulfate inevitably results in higher sulfate yields and higher acid production. The quantity of sulfate introduced would in fact be even more than eq 4 and 6 indicate since Oxone is a triple salt that contains 1 mole of sulfate per mole of peroxymonsulfate.
• Leung, P. K., Betterton, E. A., & Hoffmann, M. R. (1989). Kinetics and mechanisms of the reduction of cobalt(II) 4,4′,4″,4‴-tetrasulfophthalocyanine by 2-mercaptoethanol under anoxic conditions. Journal of Physical Chemistry, 93(1), 430-433.
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  Abstract: The kinetics and mechanism of reduction of cobalt(II) 4,4′,4″,4‴-tetrasulfophthalocyanine by 2-mercaptoethanol to yield cobalt(I) tetrasulfophthalocyanine and 2-hydroxyethyl disulfide under anoxic conditions were investigated and the following rate law was found: v = -d[CoIITSP]T/dt = {k2k1[RSH]T[CoIITSP] T}/{2(1 + aH+/Ka1 + Ka2/aH+)(1 + α[RSH]T)}, where k2 is a rate constant for the rate-limiting electron-transfer step, and K1 is the equilibrium constant for the complexation of a CoTSP dimer with thioethanol; Ka1 and Ka2 are the apparent acid dissociation constants of HOC2H4SH and HOC2H4S-, respectively; α is K1/(1 + aH+/Ka1 + Ka2/aH+); aH+ is the hydrogen ion activity. A nonlinear least-squares fit of the experimental data to the above rate law gave k2 = 228 ± 3.8 s-1 and K1 = 117 ± 2.5 M-1 at 27°C at μ = 0.4 M. © 1989 American Chemical Society.
• Betterton, E. A., & Hoffmann, M. R. (1988). Henry's law constants of some environmentally important aldehydes. Environmental Science and Technology, 22(12), 1415-1418.
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  Abstract: The Henry's law constants of seven aldehydes have been determined as a function of temperature by bubble-column and by head-space techniques. The compounds were chosen for their potential importance in the polluted troposphere and to allow structure-reactivity patterns to be investigated. The results (at 25°C) are as follows (in units of M atm-1): chloral, 3.44×105; glyoxal, ≥3×105; methylglyoxal, 3.71×103; formaldehyde, 2.97×103; benzaldehyde, 3.74×101. A hydroxyacetaldehyde, 2.97×104; acetaldehyde, 1.14×101. A plot of R.W. Taft's parameter, Σσ*, vs log H* (the apparent Henry's law constant) gives a straight line with a slope of 1.72. H* for formaldehyde is anomalously high, as expected, but the extremely high value for hydroxyacetaldehyde was unexpected and may indicate that α-hydroxy-substituted aldehydes could have an unusually high affinity for the aqueous phase.
• Betterton, E. A., & Hoffmann, M. R. (1988). Oxidation of aqueous SO₂ by peroxymonosulfate. Journal of Physical Chemistry, 92(21), 5962-5965.
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  Abstract: Recent model calculations suggest that peroxymonosulfate may constitute a significant fraction of the total sulfur budget in remote tropospheric water droplets such as cloud, fog, and rain. However, little is known about the oxidation of dissolved SO2 by peroxymonosulfate (HSO5-). We have found in aqueous solution that the rate of S(IV) oxidation is comparable to the rate of oxidation of S(IV) by hydrogen peroxide and that HSO4- is the only detectable oxidation product. We propose a mechanism in which the rate-determining step involves the acid-catalyzed decomposition of a peroxide-bisulfite intermediate to disulfate ion, S2O72-, and ultimately to sulfuric acid. The rate equation for this mechanism is -d[HSO3-]/dt = k1(k2/k-1)Ka1{H +}[HSO5-][S(IV)]/((1 + (k2/k-1){H+})(Ka1 + {H+})), where k1 = 1.21 × 106 M-1 s-1, k2/k-1 = 5.9 M-1, k1k2/k-1 = 7.14 × 106 M-2 s-1, Ka1 = 2.64 × 10-2 M at 5°C, and μ = 0.2 M. The activation parameters are ΔHk1≠ = 25.74 ± 0.77 kJ mol-1 and ΔSk1≠ = -88.1 ± 2.7 J mol-1 K-1. © 1988 American Chemical Society.
• Betterton, E. A., Erel, Y., & Hoffmann, M. R. (1988). Aldehyde-bisulfite adducts: prediction of some of their thermodynamic and kinetic properties. Environmental Science and Technology, 22(1), 92-99.
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  Abstract: Stability constant (K//1) for the reaction of acetaldehyde and hydroxyacetaldehyde with NaHSO//3, determined spectrophotometrically in aqueous solution, were found to be (6. 90 plus or minus 0. 54) multiplied by 10**5 M** minus **1 and (2. 0 plus or minus 0. 5) multiplied by 10**6 M+ZZ minus **1, respectively, where K//1 (corrected for aldehyde hydration) equals left bracket RCH(OH)SO//3** minus right bracket / left bracket RCHO right bracket left bracket HSO//3** minus right bracket ( mu equals 0. 2 M; 25 degree C). Acid dissociation constants (pK//a//3) of a series of alpha -hydroxyalkanesulfonate salts, RCH(OH)SO//3** minus , were found to be 11. 46 (CH//3-), 11. 28 (H-), 10. 30 (HOCH//2-), 10. 33 (C//6-H//5-), 10. 31 (CH//3CO-), and 7. 21 (Cl//3C-) ( mu equals 0 M; 25 degree C). Simple straight-line relationships were found to exist between Taft's sigma * parameter and a number of thermodynamic and kinetic properties of some aldehydes. Additional aspects of the subject are discussed.
• Betterton, E. A., & Hoffmann, M. R. (1987). Kinetics, mechanism, and thermodynamics of the reversible reaction of methylglyoxal (CH₃COCHO) with S(IV). Journal of Physical Chemistry, 91(11), 3011-3020.
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  Abstract: At pH ≤2 the following rate law for the formation of hydroxyacetylmethanesulfonate (HAMS) from methylglyoxal (MG) and S(IV) (H2O·SO2, HSO3-, SO32-) is obtained: d[HAMS]/dt = (((k0α1[H+]/Ka0) + k1α1 + k2α2)[S(IV)][MG]0)/(1 + Kd + Kd[H+]/Ka0), where α1 and α2 are the fractional concentrations of HSO3- and SO32-, respectively; k0 is the rate constant for the reaction of HSO3- with the carbocation aldehyde species (CH3COC+HOH); k1 and k2 are the rate constants for the reaction of unhydrated MG with HSO3- and SO32-, respectively; Kd is the dehydration constant of hydrated MG; and Ka0 is the acid dissociation constant of the carbocation. At pH ≥4 the rate of formation of HAMS is determined by the rate of dehydration of the diol form of (hydrated) MG: d[HAMS]/dt = kd[MG]/(1 + Kd + Kd[H+]/Ka0), where kd = kw + kH[H+] + kOH[OH-] + kA[A] + kB[B], and kW is the intrinsic (water) rate constant; kH and kOH are the specific acid and base rate constants; and kA and kB are the general acid (A) and base (B) rate constants. Between pH 2 and 4, biexponential kinetics are observed because, under our conditions, the rates of dehydration and of S(IV) addition become comparable. Over the pH range 0.7-7.0, the dissociation of HAMS follows the rate law: d[S(IV)]/dt = ((k-0[H+] + k-1 + k-2Ka3/[H+])Ka4[H +][HAMS])/([H+]2 + Ka4[H+] + Ka3Ka4), where k-0, k-1, and k-2 are the reverse of the analogous forward rate constants defined above and Ka3 and Ka4 are the acid dissociation constants of the sulfonate anion and the sulfonic acid, respectively. Experiments to determine the effect of temperature on the rate (and equilibrium) constants indicate a marked effect of ΔS‡ (and ΔS298) on the relative magnitude of these constants. © 1987 American Chemical Society.
• Chemaly, S. M., Betterton, E. A., & Pratt, J. M. (1987). The chemistry of vitamin B₁₂. Part 27. The cage phosphite ester 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane and the anionic dimethyl phosphite as ligands for cobalt(III) corrinoids. Journal of the Chemical Society, Dalton Transactions, 761-767.
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  Abstract: The equilibrium constant for the substitution of co-ordinated H 2O in aquocobalamin by 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2] octane (L4) has been determined in aqueous solution at 25 °C by u.v.-visible spectrophotometry to be log K = 7.2; comparison with the estimated pK of 1.5 for the protonation of L4 shows the marked preference of L4 for CoIII over the proton. The cobinamide and acidified cobalamin (with protonated dbzm, the nucleotide base) containing anionic dimethyl phosphite (L5) show a reversible temperature-dependent change in spectrum, ascribed to an equilibrium between five- and six-co-ordinate forms with axial ligands L5-Co and L5-Co-OH2 respectively. Axial ligands L4 and L5 exert a similar cis effect (based on wavelength of the γ band), viz. H2O < dbzm < CN- < SO32- ≈ L4 ≈ L5 < HC≡C- < CH2CH- < CH3-, but a very different trans effect (based mainly on equilibrium constants), viz. H2O < dbzm < L4 < CN- < SO32- ≈ HC≡C- < L5 ≈ CH2=CH- < CH3-.
• Betterton, E. A., Olson, T. M., & Hoffmann, M. R. (1986). DICARBONYLS AS S(IV) RESERVOIRS.. American Chemical Society, Division of Petroleum Chemistry, Preprints, 31(2), 573-576.
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  Abstract: S(IV) in the form of SO//2 multiplied by (times) H//2O, HSO//3** minus or SO//3**2** minus reacts with glyoxal to yield 1,2-dihydroxy-ethanedisulfonate (DHES) and it reacts with methylglyoxal to yield 1-hydroxyacetylmethanesulfonate (HAMS). The kinetics of both the association and the dissociation of the aldehyde-bisulfite adducts was studied in aqueous solution as a function of pH. The rate of association was studied directly by UV-visible spectrophotometry under pseudo-first-order conditions while the rate of dissociation was studied indirectly by using an iodide electrode to measure the rate of formation of I** minus as the sulfonates dissociated in I//2 solution.
• Betterton, E. A., Olson, T. M., & Hoffmann, M. R. (1986). Dicarbonyls as S(IV) reservoirs. Preprints Symposia, 31(2), 573-576.
• Baldwin, D. A., Betterton, E. A., Chemaly, S. M., & Pratt, J. M. (1985). The chemistry of vitamin B₁₂. Part 25. Mechanism of the β-elimination of olefins from alkylcorrinoids; evidence for an initial homolytic fission of the Co-C bond. Journal of the Chemical Society, Dalton Transactions, 1613-1618.
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  Abstract: Equilibrium constants (log10K/dm3 mol-1) have been determined for the co-ordination of imidazole by the five-co-ordinate alkylcobinamides with R (= alkyl) = Me (0.9), Et(-0.5), neopentyl (np) (-1.4), Pri (
• Betterton, E. A., Chemaly, S. M., & Pratt, J. M. (1985). The chemistry of vitamin B₁₂. Part 26. Co-ordination of the malonitrile anion by Co^III corrinoids: First experimental determination of equilibrium constants for the co-ordination of a tetrahedral carbanion by a transition-metal ion. Journal of the Chemical Society, Dalton Transactions, 1619-1622.
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  Abstract: Equilibrium constants for the substitution of co-ordinated H2O by the malonitrile anion, CH(CN)2-, in the CoIII corrinoids aquocobalamin and diaquocobinamide have been determined in aqueous solution at 25 °C as log K(dm3 mol-1) = 7.4 and ca. 11.5 respectively.
• Betterton, E. A. (1984). ROMANS DID IT IN THE FORUM.. CHEMSA, 10(1), 267-268.
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  Abstract: A discussion is presented of cement manufacture, setting and hardening and the effect of the water-to-cement ratio.
• Baldwin, D. A., Betterton, E. A., & Pratt, J. M. (1983). The chemistry of vitamin B₁₂. Part 20. Diaquocobinamide: pK values and evidence for conformational isomers. Journal of the Chemical Society, Dalton Transactions, 217-223.
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  Abstract: An improved method for preparing aqueous solutions of diaquocobinamide without hydrolysis products is described. The pKa values have been determined in 0.2 mol dm-3 NaClO4 at 25 °C as pK1 = 5.9 ± 0.1 and pK2 = 10.3 ± 0.2 and are shown to involve one proton each. Evidence is presented that diaquo-, aquohydroxo-, and dihydroxo-cobinamide exist in solution as isomers depending on hydrogen bonding between the axial ligands and different amide side-chains.
• Baldwin, D. A., Betterton, E. A., & Pratt, J. M. (1983). The chemistry of vitamin B₁₂. Part 21. Ethynylaquocobinamide: Novel reaction of diaquocobinamide with acetylene catalysed by copper ions. Journal of the Chemical Society, Dalton Transactions, 225-229.
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  Abstract: Copper ions catalyse the reaction of diaquocobinamide with acetylene in aqueous solution at room temperature to give ethynylaquocobinamide as a mixture of the two isomers which differ in the relative orientation of the axial ligands. This leads to the first reported value for an equilibrium constant (axial ligands only given) involving the substitution of co-ordinated H2O by HC2- of K = [HC2-Co-OH2]/([H2O-Co-OH2] [HC2-]) ≥ 1023 dm3 mol-1. Equilibrium constants have been determined for the substitution of co-ordinated H2O in ethynylaquocobinamide by OH- (pK = 13.0 ± 0.1), CN- (log10K ≥ 6.8), and imidazole (log10K = 3.4), which confirm the position of HC2- between cyanide and vinyl in the trans-effect series for CoIII corrinoids.
• Baldwin, D. A., Betterton, E. A., & Pratt, J. M. (1983). The chemistry of vitamin B₁₂. Part 22. Steric effects in the co-ordination of amines by cobalt(III) corrinoids. Journal of the Chemical Society, Dalton Transactions, 2217-2222.
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  Abstract: The following equilibrium constants (given as log10K/dm3 mol-1) have been determined by spectrophotometry for the substitution in cobalt(III) corrinoids of co-ordinated H2O by various amines B with different trans ligands X in aqueous solution (I = 0.2 mol dm-3) at 25 °C: X = 5,6-dimethylbenzimidazole (dbzm), B = NH2Me (ca. 6), NHMe2 (3.4), NMe3 (≤1), NH2Et (5.3), NH2Pri and NH2But (both ≤1); X = CN-, B = NH2Me (3.4), NHMe2(2.0), NMe3(ca. 0); X = vinyl, B = NH3 (-0.06), NH2Me (+0.04), NHMe2 and NMe3 (both ≤ - 1). These results show that steric effects increase in importance as the donor power of the trans ligand X decreases (from vinyl through CN- to dbzm) and that significant steric effects are caused by substitution on the β (C) atom as well as on the α (N) atom.

Proceedings Publications

• Galarneau, T., Powell, M., & Betterton, E. A. (2019, January). Synoptic Analysis of the Epic Rainstorm in Kauai on 14–16 April 2018. In 99th American Meteorological Society Annual Meeting.

Presentations

• Loh, M. M., Lothrop, N. Z., Sugeng, A., Felix, O. I., Betterton, E. A., Saez, A. E., Klimecki, W., Wilkinson, S. T., & Beamer, P. I. (2014, October). Environmental Exposures to Children at a Legacy Mine Site. International Society of Exposure Science 24th Annual Meeting. Cincinnati, OH: International Society of Exposure Science.
• Beamer, P. I., Waltz, A. N., Wolf, A. A., Lutz, E. A., & Betterton, E. A. (2013, August). Concentration of Volatile Organic Chemicals in Small Businesses Located in a Low-Income Latino Community. Joint Conference for International Society of Exposure Science, International Society of Environmental Epidemiology, and International Society of Indoor Air Quality. Basel, Switzerland.

Poster Presentations

• Chang, H. I., Lorenzo, A. T., Castro, C. L., Betterton, E. A., Leuthold, M. S., Holmgren, W. F., & Cao, Y. (2017, January). An Evaluation of Nine ARW-WRF Microphysics Schemes for Solar Power Forecast in Arizona. 97th Annual Meeting of the American Meteorological Society. Seattle.
• Ramirez, M. D., Saez, A. E., Betterton, E. A., & Manjon, I. (2017, March). Assessing the Capability of Plants as In-Situ Air Pollution Monitors: A Pilot Study Conducted in Arizona.. University of Arizona SWESxUniversity of Arizona SWESx.