The overall purpose of this project is to assess the environmental mobility, biotreatability, and epigenetic toxicity of PAH's and PCB's contained in "coal tars" and "transformer oils" spilled or disposed of in subsurface soil and sediment systems. Th proposed research will examine: (i) sorption, sequestration, and desorption processed of mixed non-aqueous phase liquid (NAPL) components as factors controlling their environmental mobility in relation to the chemical structure and character of soil and sediment organic matter; (ii) relationships between the ecology and physiology of indigenous microbial consortia and the affinity of contaminants to microbial transformation as factors controlling their biotreatability; and, (iii) the impact of these processes on epigenetic toxicity as a measure of the toxic effects of mixed organic spills of NAPL contaminants in natural porous media prior to and after biotreatment. The data obtained will address the efficacy of risk-based endpoints as alternatives to absolute cleanup goals for the remediation of contaminated soils and sediments. We propose to evaluate the sorption/desorption behavior of NAPL-associated PAHs and PCBs for a range of well- characterized soils have different diagenetic histories and thus chemically and structurally different natural organic matter (NOM) compositions. The sorption of PAHs and PCBs from NAPL phase to these spoils and their subsequent sequestration and desorption will be studied to simulate their NAPL phase to these soils and their subsequent sequestration and desorption will be studied to stimulate their fate in "real-world" NAPL contaminated spill and disposal sites. The availability of PAHs and PCBs to microbial degradation both in the NAPL and in the soil and sediment solid phases contaminated by these physiological structures of indigenous microbial consortia. The epigenetic toxicity of mixed organic spills will be measured by a gap of junctional intercellular communication as a criteria for assessment of the reduction in overall toxicity effected by sequestration and microbial transformation processes.