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ORGANIC CHEMICAL TRANSPORT TO GROUNDWATER
Citation:
Enfield, C. AND S. Yates. ORGANIC CHEMICAL TRANSPORT TO GROUNDWATER. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-90/203 (NTIS PB91137059).
Description:
The use of pesticides in the production of agricultural commodities is widespread. Since nearly one-half of the U.S. population relies on groundwater as their source for drinking water, contamination potential of groundwater, because of pesticide manufacture and use, must be understood. The processes of sorption, biotic and abiotic transformation, and vapor transport have been discussed in previous chapters of this book. he objective of this chapter is to integrate the above processes into chemical mass transport models that can be used to forecast environmental exposure. Almost any modeling activity related to groundwater starts with a water flow model, since, for any significant change to take place in the flow field, flow is an essential ingredient. an der Heijde et al reviewed several hundred groundwater management models from around the world and classified them in a variety of ways. Their review included both saturated and unsaturated flow models along with identifying the source and availability of computer codes for the models. Considering this review and several other reviews, the current chapter will emphasize chemical transport rather than mass water flow. or completeness, a brief overview of water flow through saturated and unsaturated soils will be included. ecoupling the water and chemical transport is a major assumption in the following discussion. This means that the influence of the chemical is insignificant on water flow, and properties such as density gradients that can cause fluid movement can be ignored. This makes it possible to calculate the water flux independent of the chemical and then use the water fluxes in calculating the chemical flux.