Development of an integrated approach for the removal of tributyltin from waterways and harbors

摘要

Tributyltin (TBT), an effective biocide frequently used (in the past) as a paint additive on ship hulls to prevent fouling, has accumulated into sediments of harbors and waterways. In the framework of a LIFE-Environment project, we are currently investigating the extent of TBT-contamination in the port of Antwerp (Belgium) and possible means of remediation. Average concentrations of 50-1000 μg/kg DW were found, however with peaks of more than 40000 μg/kg DW close to the ship repair site. In lab-scale experiments, resuspen-sion of such sediment particles was shown to pose a risk of TBT-remobilization, particularly at a pH higher than 8.1. Sampling of the water phase during an on-site dredging operation confirmed these results, as TBT-concen-trations of more than 500 ng/L were detected at a water pH of 8.29. Although not acute toxic, such high concentrations demand a cautious dredging approach and the need for sediment remediation (bio-, phyto-, electrochemical, thermal,...).