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(M/EH071) Biological Degradation of Tributyltin under Defined Conditions at Different Temperatures. Jastorff, Bernd2, Brandsch, Romana1,2, 2 1 ABSTRACT- Due to its use in antifouling paints of ships, large quantities of tributyltin (TBT) are released into the marine environment. As a result of its low water solubility and its lipophilic character TBT is readily sorbed by particles and sediments. Mainly in the marine harbours from North Germany TBT contents up to 70 mg/kg dry weight are found. Since the harbours have to be dredged regularly to allow ships to pass, large quantities of TBT-containing sediments have to be dealt with, which formerly were send to the bottom of North Sea. Since 1998 it is forbidden to dispose sediments with a TBT-content greater than 0.1 mg/kg DW into the North Sea. Because dehydration followed by deposition is very expensive, a pilot project was started in order to investigate the effects of deposition on land. The main purpose of the project is to monitor the biological degradation of TBT. Parallel to this field study, laboratory experiments under defined conditions were carried through. We investigated the effects of temperature ( 6 temperatures from 5 to 55°C ) on biological degradation of TBT in sediment, but also marine water, under aerobic and anaerobic conditions. The results of those experiments will be presented and they clearly show that the degradation of TBT is much faster under aerobic conditions (half-life of several month) and is additionally accelerated by increasing temperature. The uptake of TBT by several plants growing in these sediment was also investigated. With these investigations we expect to find a possible solution for the disposal of TBT-containing harbour sediments, without using chemical or thermal treatment and to evaluate the risk for a land deposition. Key words: tributyltin, biological degradation, effects of temperature, risk assessment |
