FIELD MEASUREMENT AND MODELING THE FATE OF ANILINE AND LINDANE IN A UK LOWLAND RIVER

The application of models to predict the behaviour of chemicals in the aquatic environment will assume increasing importance as the sophisti cation of river pollution management increases. A field validation of a model which enables such predictions, the US EPA EXAMS II model, is reported. The study was carried out on a stretch of a UK lowland river , the River Calder in West Yorkshire, and utilised a sewage treatment works (STW) effluent discharge as a point source of the two chemicals, aniline and lindane, modelled. Concentrations of aniline and lindane were measured in samples of water, suspended particulates and sediment s taken from the river and STW effluent and the measured results compa red with those predicted by the EXAMS model. Good agreements were gene rally obtained between the model predictions and the measured values f or the water and bed sediment, but the levels measured in the suspende d particulates were significantly higher than those predicted. The mos t likely explanation for this discrepancy was that the equilibrium par titioning approach employed by EXAMS was inappropriate for the suspend ed particulate associated chemicals. However, since the majority (>>95 %) of both aniline and lindane in the water column was in the dissolve d phase, this was not a significant drawback to the use of EXAMS for t he prediction of fate and behaviour.