Spatial and temporal patterns of dieldrin pollution in the holme catchment, West Yorkshire, England

West Yorkshire is one of the few remaining areas in the country where persistent organochlorine insecticides such as dieldrin are used for the mothproofing of textiles. Concentrations of dieldrin in the River Holme catchment were measured during 1980–1981.

A study of both spatial and temporal patterns of dieldrin concentration was undertaken. The spatial pattern revealed that the concentration decreased with the distance downstream of recognised discharges and that dieldrin was absent at detectable concentrations elsewhere in the system.

At selected stations, a detailed temporal survey was carried out and revealed that, close to the pollution source, massive changes in dieldrin concentration occurred over short time periods. As distance from the source increased, these changes were much less marked.

Earlier studies of dieldrin pollution in the catchment did not take into account the massive changes in concentration and attempted to predict mass flows for dieldrin in the system.

The implications of these fluctuations in concentration for future studies are therefore briefly discussed.