ORGANOTIN IN THE MARINE SURFACE MICROLAYER AND SUBSURFACE WATERS OF SOUTH-WEST ENGLAND - RELATION TO TOXICITY THRESHOLDS AND THE UK ENVIRONMENTAL-QUALITY STANDARD

Comparison of organotin concentrations in seawater collected before and after the UK government introduced legislation in 1986 and 1987 to limit the input of tributyltin (TBT) compounds to the marine environment, shows that the legislation is beginning to take effect. Organotin concentrations began to decline in 1988 and continued to do so in 1989 in both the surface microlayer and sub-surface waters. The greatest changes have occurred in marinas, with a maximum 10-fold decline in sub-surface waters and 20-fold in the microlayer. Nevertheless TBT concentrations throughout the water column still exceed the environmental quality standard and toxicity threshold values known to cause chronic toxic effects in a number of marine species.