Chemical monitoring and risk assessment of 56 pesticides in the Ave River and adjoining Atlantic coastline (Iberian Peninsula, Portugal).

The Ave basin (North Atlantic Ocean Ecoregion) is highly disturbed by anthropogenic activities. The amounts and distribution patterns of 56 priority pesticides (fungicides, herbicides, and insecticides) dissolved in the aqueous phase (DAP) and suspended particle matter (SPM) were evaluated seasonally along the river, estuary and coastline. Over 83 % of the GC-MS/MS-identified pesticides were quantified in DAP and 91 % in SPM. Pesticides' average annual amounts were ≅316 ng/L and 1.3 μg/g (fungicides), ≅272 ng/L and 2.2 μg/g (herbicides) and ≅1344 ng/L and 6.6 μg/g (insecticides). Invertebrates were the most vulnerable trophic level in the theoretical assessment of pesticide mixture hazards. This hypothesis was strengthened by acute in vivo assays using Artemia salina and Daphnia magna. These data, and the fact that 38 % of pesticides showed concentrations above the maximum established by the European legislation, plus the high concentrations of nitrates, nitrites, ammonia and phosphates, request further depollution actions in this region.