| Abstract
| - Sediments contaminated with triorganotin compounds(TOTs) are abundant in areas with high shipping activities.In such areas, sediment dwellers such as chironomidsmay introduce these very toxic contaminants into foodwebs.In this work, we studied systematically the uptake andelimination of tributyltin (TBT) and triphenyltin (TPT) withlarvae of Chironomus riparius at pH 5 and pH 8 and in theabsence and presence of Aldrich humic acid (AHA).Both uptake and elimination data could be simultaneouslyfit by a two-pool model, and uptake, excretion, andmetabolism rate constants could be derived with verygood reproducibility. Bioconcentration was found to besignificantly lower for TBT than for TPT, although TBT ismore hydrophobic. The major reason was the rapid metabolismof TBT to dibutyltin (DBT) and further to monobutyltin(MBT). Apparent AHA−water distribution ratios (DAHA) werederived from bioconcentration experiments in the presenceof AHA and were compared with DAHA values determinedin dialysis experiments. Except for some explainablediscrepancies, a good agreement between both sets ofDAHA values was found, confirming the hypothesis that TOTsassociated with AHA are not bioavailable. The results ofthis work demonstrate that chironomids are well-suitedorganisms to study the speciation and bioconcentration oforganotin compounds present in sediment pore waters.
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