An Air Quality Data Analysis System for Interrelating Effects,Standards, and Needed Source Reductions: Part 13— Applying the EPA Proposed Guidelines for Carcinogen Risk Assessment to a Set of Asbestos Lung Cancer Mortality Data

Abstract

The Clean Air Act Amendments of 1990 (CAAA-90) list 189 hazardous air pollutants (HAPs) for which “safe” ambient concentrations are to be determined. The primary purpose of this paper is to develop two mathematical models, lognormal and logarithmic, that effectively express excess lung cancer mortality as a function of asbestos concentration for an example set of data and also to suggest using these two models for additional HAPs. The secondary purpose of this paper is to calculate a “safe” asbestos concentration by first assuming a default linear extrapolation (to one excess death per million people, as specified for carcinogenic HAPs). The resulting “safe” concentration is an impossible-to-achieve 1/1000 of present background asbestos concentrations. A letter to the editor and a response in this Journal issue use additional asbestos data that suggest that the “safe” concentration should be about 730 times higher than first calculated here and that a default nonlinear extrapolation should be used instead, with the “safe” concentration proportional to the desired mortality level raised to the 0.39 power. These results suggest that the most important problem in setting a “safe” concentration for each carcinogenic HAP is to determine the correct nonlinear extrapolation to use for each HAP.     

System Dynamics to Sustainable Water Resources Management in the Eastern Snake Plain Aquifer Under Water Supply Uncertainty1

Abstract: Water supply uncertainty continues to threaten the reliability of regional water resources in the western United States. Climate variability and water dispute potentials induce water managers to develop proactive adaptive management strategies to mitigate future hydroclimate impacts. The Eastern Snake Plain Aquifer in the state of Idaho is also facing these challenges in the sense that population growth and economic development strongly depend on reliable water resources from underground storage. Drought and subsequent water conflict often drive scientific research and political agendas because water resources availability and aquifer management for a sustainable rural economy are of great interest. In this study, a system dynamics approach is applied to address dynamically complex problems with management of the aquifer and associated surface‐water and groundwater interactions. Recharge and discharge dynamics within the aquifer system are coded in an environmental modeling framework to identify long‐term behavior of aquifer responses to uncertain future hydrological variability. The research shows that the system dynamics approach is a promising modeling tool to develop sustainable water resources planning and management in a collaborative decision‐making framework and also to provide useful insights and alternative opportunities for operational management, policy support, and participatory strategic planning to mitigate future hydroclimate impacts in human dimensions.     

Nonideal transport of contaminants in heterogeneous porous media: 10. Impact of co-solutes on sorption by porous media with low organic-carbon contents

The impact of co-solutes on sorption of tetrachloroethene (PCE) by two porous media with low organic-carbon contents was examined by conducting batch experiments. The two media (Borden and Eustis) have similar physical properties, but significantly different organic-carbon (OC) contents. Sorption of PCE was nonlinear for both media, and well-described by the Freundlich equation. For the Borden aquifer material (OC = 0.03%), the isotherms measured with a suite of co-solutes present (1,2-dichlorobenzene, bromoform, carbon tetrachloride, and hexachloroethane) were identical to the isotherms measured for PCE alone. These results indicate that there was no measurable impact of the co-solutes on PCE sorption for this system. In contrast to the Borden results, there was a measurable reduction in sorption of PCE by the Eustis soil (OC = 0.38%) in the presence of the co-solutes. The organic-carbon fractions of both media contain hard-carbon components, which have been associated with the manifestation of nonideal sorption phenomena. The disparity in results observed for the two media may relate to relative differences in the magnitude and geochemical nature of these hard-carbon components.     

Analytical Solutions to the Linearized Boussinesq Equation for Assessing the Effects of Recharge on Aquifer Discharge1

Boggs, Kevin G., Robert W. Van Kirk, Gary S. Johnson, Jerry P. Fairley, and P. Steve Porter, 2010. Analytical Solutions to the Linearized Boussinesq Equation for Assessing the Effects of Recharge on Aquifer Discharge. Journal of the American Water Resources Association (JAWRA) 46(6):1116–1132. DOI: 10.1111/j.1752-1688.2010.00479.x Abstract: There is a need to develop a general understanding of how variations in aquifer recharge are reflected in discharge. Analytical solutions to the linearized Boussinesq equation governing flow in an unconfined aquifer provide a unified mathematical framework to quantify relationships among lag time, attenuation and distance between aquifer recharge and discharge and the effect of an up-gradient no-flow boundary. We applied this framework to three types of recharge: (1) instantaneous, (2) periodic, and (3) constant rate for a finite duration. When the temporal scale of recharge exceeds the diffusive aquifer time scale, recharge will be reflected in discharge quickly and with little attenuation. When aquifer time scale is large, most recharge events are shorter in scale than that of the aquifer, resulting in large attenuation. Attenuation is more sensitive to boundary effects than lag time, and boundary effects increase as recharge time scale increases. Boundary effects can often be ignored when the recharge source is farther than 1/3 of the domain length away from the no-flow boundary. We illustrate analytical results with application to the economically critical Eastern Snake River Plain Aquifer in Idaho. In this aquifer, detectable annual and decadal cycles in discharge can result from recharge no farther than 20 and 60 km away from the discharge point, respectively. The effects of more distant, long-term recharge can be detected only after a time lag of several decades.     

Effect of fatty acids and oils on photodegradation of azadirachtin‐A

Abstract

Azadirachtin‐A on exposure to UV‐light (254 nm) as a thin film on glass surface gave a isomerised (Z)‐2‐ methylbut‐2‐enoate product. Half‐life of azadirachtin‐A as thin film under UV light was found to be 48 min. Azadirachtin ‐A was irradiated along with saturated and unsaturated fatty acids, and fatty oils under ultra‐violet light as thin film. Saturated fatty acid increased the rate of photodegradation of azadirachtin‐A, whereas unsaturated fatty acids such as oleic, linoleic and elaidic acid reduced the rate of degradation. Castor, linseed and olive oil accelerated the rate of degradation, whereas neem oil showed no or little change in the rate of degradation of azadirachtin‐A. None of these fatty acids and fatty oils were effective in controlling the rate of degradation of azadirachtin‐A under UV‐light as thin film.     

The Radial Distribution of Sulfur Dioxide Source Strength and Concentration in Nashville

This progress report describes the National Air Pollution Technical Information Center currently under development in the Division of Air Pollution, Public Health Service. It briefly reviews the report "Science, Government, and Information" (Weinberg Report) and the White House delegation of responsibility to the Department of Health, Education, and Welfare for handling air pollution technical information.     

Control of Contaminant Emissions From Fossil Fuel-Fired Boilers

The importance of fuels combustion was brought into sharp focus recently in a report on air pollution to the United States Senate in which it was stated, “These processes replace usable air with potentially harmful pollutants, and the capability of the atmosphere to disperse and dilute these pollutants—especially in urban areas where people, vehicles, and industries congregate in even greater numbers—is strictly limited.”¹ The overwhelming burden of emissions of sulfur compounds, as well as nitrogen compounds and particulate matter in the U. S. today, originates from the burning of coal and fuel oil in stationary combustion sources. Thus, combustion has a large influence on the quality of the atmosphere in most urban areas. The air pollution effects of these contaminants are many and varied and all are objectionable and undesirable. Without a doubt, the most serious air pollution problem in the nation today is that created by the combustion of fossil fuels.     

Mathematical Modeling of Photochemical Smog Using the PICK Method

A new method for solving the turbulent atmospheric diffusion equation has been developed based on Lagrangian mass points, or particles moving through an Eulerian grid. The method is one of a family of Particle-/n-Cell techniques but is a unique extension to incorporate the effects of turbulent diffusion based on K-theory; thus the acronym PICK.

In the three-dimensional computer-aided model, NEXUS (Numerical EXamination of Urban Smog), this method has been applied to simulation of carbon monoxide (CO) in Los Angeles. For CO the NEXUS simulation was within 20% of observed day-averaged concentrations at 12 stations and the hour-averages were also in good agreement. This model was extended to include the effects of photochemical smog in Los Angeles. The results of the photochemical simulation were also qualitatively correct due to rapid NO to NO₂ conversion in the simulation.