Occurrence of pesticides in rain of the Aries River Basin, Greece

The Aries River Basin is one of the most developed agricultural areas of Greece. Samples from a total of 205 rain events collected from eight sampling stations during 1997-1998 were analyzed for pesticide residues of which 186 events (90%) yielded at least one positive detection. Among 160 target pesticides and some major conversion products recovered by solid-phase extraction (SPE) and analyzed by GC-ITMS, 47 compounds were found in at least one rain event. The most frequently found pesticides included alachlor (49%), lindane (44%), parathion-methyl (38%), atrazine (30%), quintozene (28%), metolachlor (24%), prometryne (23%), and molinate (22%). Occurrences of diazinon, chlorpyrifos-ethyl, methidathion, ethofumesate, and parathion accounted for 14-17% of the samples analyzed. The remaining target analytes were present in less than the 10% of the analyzed samples. Concentrations of individual compound ranged from 0.002 to 6.82 mu g/L. Greater pesticide concentrations occurred during application seasons. The estimated annual deposition rates for the sum of the pesticides ranged from 51 to 395 mu g/m(2) of soil surface.