Pesticides in groundwater : some observations on temporal and spatial trends

Following a monitoring programme of private shallow boreholes a total of 22 different pesticides were detected in 14 shallow boreholes in the Triassic Sherwood Sandstone aquifer of South Yorkshire between January 2002 and November 2003. Of the 294 positive detections made, 34% were detected in excess of the prescribed concentration or value (PCV) (drinking water standard) for individual pesticides. Pesticides were detected in 11 (78%) of the boreholes, and in 8 (57%) at concentrations exceeding the PCV on at least one occasion. These findings were complemented by data from deeper boreholes in which concentrations exceeding the PCV were also detected. Pesticide occurrence could be related to landuse; mecoprop and isoproturon were frequently detected at several locations reflecting the arable landuse, dicamba at a golf course, and atrazine, propazine and terbutryn near a railway. Temporal variations have emerged at individual sites and across the study area as the results of extended and frequent monitoring.