TEMPORAL DISTRIBUTION OF ORGANOTINS IN THE AQUATIC ENVIRONMENT - 5 YEARS AFTER THE 1987 UK RETAIL BAN ON TBT BASED ANTIFOULING PAINTS

In 1987 the UK government introduced legislation to control the sale of tributyltin (TBT) based paints. Between 1990-92, a monitoring programme of waters and surficial sediments from six estuarine river systems was undertaken for TBT and its degradation products; dibutyltin (DBT) and monobutyltin (MBT). Despite the retail ban on tributyltin based antifouling paints for use on vessels <25 m in length, water concentrations exceeded the Environmental Quality Target (EQT) at certain locations, 3-4 years after its implementation. However, since 1991, water column concentrations have declined significantly and most are now below analytical detection limits (<3 ng l-1). Butyltin concentrations in surficial sediments displayed high spatial variability. Sediment concentrations have generally decreased since 1990, with highly contaminated sites being confined to marinas and boatyards. The present study illustrates that controls instituted in 1987 by the UK on the use of TBT based paints have been effective in reducing estuarine water column, and to a lesser extent, surficial sediment concentrations, but over a 5 year time span.