Assessing the impact of viticulture plant protection products in the pollution of surface and ground waters

Plant protection products, particularly fungicides and insecticides, are intensively used in viticulture. Washing from leaves of vines, runoff transport, and soil penetration might lead to pollution of surface and ground waters. Herein, we present a systematic study on the occurrence and evolution of fungicides and insecticides in samples from two major wine production areas in Spain (La Rioja and Galicia). Above 400 water samples, corresponding to eight sub-zones, from two regions with different pedoclimatic conditions, were analyzed by liquid chromatography accurate mass spectrometry. Total residues of target compounds followed a homogeneous distribution in all sub-zones except one; nevertheless, their average values were slightly lower in La Rioja than in Galicia (181.1 ng L^-1 and 260.8 ng L^-1, respectively). The highest pollution levels in the complete set of samples were measured in summer campaigns, corresponding to the most intensive application season of fungicides and insecticides. Nonetheless, in some wells, residues increased from summer to autumn, confirming their leaching to ground water. Fungicides were prevalent versus insecticides with distribution patterns varying between regions. Tetraconazole, fluopyram and boscalid recorded higher detection frequencies in waters from La Rioja (from 16 % to 24 %) than in Galicia (between 4 % and 10 %). The opposite trend was observed for azoxystrobin (11 % vs 35 %), zoxamide (3 % vs 34 %), mandipropamide (1 % vs 27 %) and fluopicolide (1 % vs 23 %), with lower detection rates in La Rioja compared to Galicia. Attending to detection frequencies and ratios between measured and predicted non-effect concentrations, azoxystrobin, carbendazim, fluopicolid, tebuconazole and zoxamide were rated as the most environmental concerning pollutants. Suspect screening of accurate MS data revealed the presence of additional pesticides, including herbicides and their transformation products, in the monitored aquatic environments.