Butyltin compounds were investigated in surface sediments from 17 stations in Todos os Santos Bay. Analytical conditions for organotin determination in marine sediments were optimized for GC with pulsed flame photometric detection. Detection limits were: 5.4 µg kg-1 for TBT; 0.2 µg kg-1 for DBT; and 2.1 µg kg-1 for MBT, using a 610-nm filter. In general, TBT concentrations were low and in the range of <DL to 15.9 µg kg-1. Only in one of the investigated stations DBT and MBT were above detection limit despite the oxic to slightly anoxic conditions in the sediments. The presence of paint particles in the sediments and degradation in the water column during resuspension events followed by removal of the more soluble DBT and MBT may explain these observations.
butyltin speciation; sediments; Todos os Santos Bay
