Project Summary (1995-2000)

In this project, studies are conducted to investigate the fundamental processes--including diffusive and convective transport, sorption/desorption, and biodegradation--that affect the fate and transport of both the liquid and vapor phases of volatile organic compounds (VOCs) in soil and geologic sediments. Exposure assessment, an essential component of environmental risk analysis, requires quantitative approaches for estimating the distribution and persistence of pollutants in environmental media. Research focuses on the coupled and interdependent physical, chemical, and biological processes determining the transport and distribution of chemical mixtures. Relationships between VOC transport processes and field-scale geological attributes of the vadose zone are being determined. Quantitative descriptions of these relationships are being incorporated into vadose zone transport models which include modeling experiments of flow and transport. A heat-water transport model for the vadose zone is being developed and tested. This model is being coupled with the models of chemical volatilization to obtain the flux into the atmosphere.