Rather high levels of tributyltin (TBT) in sediments were found in certain areas around the Hong Kong coastline. Sediments from two contaminated sites (Tsing Yi and Yam O) and two clean sites were used to study the release of TBT contaminants from resuspended sediment to the water column by elutriate tests. The chemical analysis data of elutriates were compared with the effective or lethal concentrations from the toxicity tests of spiked solution using marine microalga (Dunaliella tertiolecta) and benthic invertebrate (Melita koreana) to assess the potential ecotoxicological impacts arising from the dredging work. Concentrations of TBT in filtered sediment elutriates were mostly below 0.002 μg/l which suggested that very little of TBT was released in soluble form. The lethal toxicity of TBT for the invertebrate expressing as 10 day-LC50 was 2.31 μg/l for TBT and the alga expressing as 48 h-EC50 was 0.46 μg/l. The results of this evaluation demonstrated that the release of TBT from two contaminated sites during dredging was unlikely to attain the effective or lethal concentrations on the two test species.
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