Chemicals in soil are subjected to environmental factors which may influence their mobility. Climatic stress can alter soil structure and chemical retaining properties and low pH can influence chemical mobility. The Toxicity Characteristic Leaching Procedure (TCLP) is being used to assess chemical mobility. The objectives of this research were to: (a) determine the leachability of specific metals and organics from soils at hazardous waste land treatment sites using the TCLP, (b) evaluate the mobility of hazardous constituents as a function of soil depth for these sites, and (c) determine the effects of weathering cycles on the leachability of these constituents.
Soils from several hazardous waste land treatment sites initially were characterized for selected metals and organics and their mobility determined using the TCLP. The soils then were subjected to repetitive freeze/thaw and wet/dry cycles, and retested using the TCLP to determine whether significant changes in chemical mobility were caused by the weathering action. Metals analyses for both the weathered and non-weathered samples indicated that, of the six metals tested, only zinc exceeded background levels consistently. No clear differences were detected when metal concentrations in TCLP extracts from weathered and nonweathered samples were compared. Organic compounds were not detected in either sets of extracts.