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SENSITIVE PARAMETER EVALUATION FOR A VADOSE ZONE FATE AND TRANSPORT MODEL
Citation:
Stevens, D. K., W. J. Grenney, Z. Yan, AND R. J. Sims. SENSITIVE PARAMETER EVALUATION FOR A VADOSE ZONE FATE AND TRANSPORT MODEL. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/2-89/039 (NTIS 89-213987), 1989.
Impact/Purpose:
publish information
Description:
This report presents information pertaining to quantitative evaluation of the potential impact of selected parameters on output of vadose zone transport and fate models used to describe the behavior of hazardous chemicals in soil. The Vadose 2one Interactive Processes (VIP) model was selected as the test model for this study. Laboratory and field experiments were conducted to evaluate the effect of sensitive soil and model paraneters on the degradation and soil partitioning of hazardous chemicals. Laboratory experiments were conducted to determine the effect of temperature, soil moisture and soil type on the degradation rate. Field-scale experiments were conducted to evaluate oxygen dynamics, through depth and time, for petroleum waste applied to soil. Results of laboratory experiments demonstrated that the sensitivity of the degradation rate to changes in temperature and soil moisture was generally greater for low molecular weight compounds and less for high molecular weight compounds. For the two soil types evaluated, soil type was more significant with regard to immobilization. Soil type was not found to have an effect on degradation kinetics for the majority of chemicals evaluated. The effect of oxygen concentration on chemical degradation as predicted by the test model was found to depend upon the magnitude of the oxygen half-saturation constant. Oxygen-linited degradation would be anticipated to occur shortly after the addition of chemicals to soil and during active microbial metabolism of chemicals.
