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(26-01) Influence of ageing on copper bioavailability in soils. Janssen, Colin1, Lock, Koen*,1, 1 J. Plateaustraat 22, Ghent, Belgium ABSTRACT- Due to long-term chemical processes, the bioavailability of metals in field soils decreases with time. Metal toxicity may therefore be overestimated if toxicity data with freshly spiked soils, a current practice, are used for the derivation of soil quality criteria. The effects of the long-term processes, called aging, on copper speciation and ecotoxicity are investigated in the present study. 25 field soils contaminated by copper run-off from bronze statues and 25 uncontaminated control soils, sampled at 5m distance from these statues, were collected in Flanders (Belgium). The soils were selected in such a way that the parameters affecting copper bioavailability (pH, cation exchange capacity, organic matter content, clay content, ...) varied considerably between the 25 sampling sites. To assess the effect of ageing on copper toxicity, the control soils were spiked at the same total copper concentration as the historically contaminated soils. Pore water copper concentrations and 0.01M calciumchloride extractable copper concentrations were higher in the freshly spiked soils compared to the contaminated field soils. Acute toxicity to the potworm Enchytraeus albidus (14 day mortality) and chronic toxicity to the springtail Folsomia candida (28 day reproduction) and to the plant Trifolium pratense (14 day growth) indicated that copper toxicity was higher in the freshly spiked compared to the contaminated soils. Furthermore, the internal copper concentration in T. pratense was closely related to the pore water copper concentration. Key words: Enchytraeus albidus, Folsomia candida, Trifolium pratense, Cu toxicity |
