Development of analytical methods for the assessment of ecotoxicological relevant soil contamination .2. Ecotoxicological analysis in soil and soil extracts

Assessment of soil quality based exclusively on chemical analysis is not feasible, because it is impossible to measure all chemical substances including their degradation products which may occur. Therefore risk assessment can only consider those substances and concentration ranges which can actually be detected by chemical analysis. Usually, in hazard assessment effect concentrations (ecotoxicity data) are related to exposure data (soil concentrations of the respective substance). Such a risk assessment is highly uncertain because data on ecotoxicity for the compartment soil are rare and insufficient. Besides the difficulties associated with the determination of mixtures of substances in the soil, it is nearly impossible to determine the substance concentrations associated with the different exposure pathways, i.e. pore water, soil air, uptake of contaminated food, and contact with particle-bound substances. The same is true for the assessment of synergistic or antagonistic actions using substance data. These difficulties can be minimized by combining chemical and ecotoxicological analysis. In the study separated batches of Cambisol, Luvisol and Chernozem were homogeneously contaminated with lindane and PCP at concentrations of 10 mg/kg and 100 mg/kg soil dry weight and with 50 and 500 mg/kg dry weight PCB 52. The toxicity of the substances in the soils were tested using several representative soil organisms (plants, nematodes, soil algae, microorganisms). Single species tests with aquatic organisms (luminescent bacteria, algae, daphnids) were used for determining the toxicity of the soil extracts. Good correlation between effects in aquatic (extract testing) and terrestrial (soil examination) test systems were obtained for the easily soluble PCP in the highest concentration. For the moderately soluble lindane, a correlation was obtained for the highest test concentration at the early sampling points. (C) 1997 Elsevier Science Ltd.