Selected herbicides in treated and untreated surface water

Atrazine, simazine, propazine, alachlor, and molinate were determined in raw (Po river) and treated waters of an advanced water supply treatment plant (WSTP) equipped with a granular activated carbon (GAC) column. Continous liquid-liquid (LLE) and C18 solid-phase (SPE) extractions were used to isolate the herbicides before the gas Chromatographic analysis using nitrogen-phosphorus (HRGC-NPD) and mass spectrometry (HRGC-MS) detection. The concentrations of atrazine in the raw water, in contrast to those of alachlor and molinate, were rather constant over the one year monitoring. The final effluent of the WSTP showed concentrations of the herbicides considered undetectable or far below the EC prescriptions. Adsorption on the GAC columns was the main process responsible for the major removal of atrazine. © 1991 Publications Division Selper Ltd