Pesticide residues in vineyard soils. Occurrence, persistence and risk assessment

The current regulatory framework requires systematic monitoring of pesticide distribution in agricultural soils to better assess associated hazards and inform authorization decisions. Herein, we evaluate the occurrence and evolution of 68 pesticides in vineyard soils from two major wine-producing regions in Spain, La Rioja and Galicia. Topsoil samples (0-10 cm) collected from vineyards (n = 87) in both regions exhibited comparable total residue levels, with median concentrations of 194 ng g^-1 in La Rioja and 131 ng g^-1 in Galicia. However, notable regional differences were observed in the detection frequency and concentration of individual compounds. Fungicides commonly applied against downy mildew, including fluopicolide, carbendazim, and dimethomorph, predominated in Galician vineyards, whereas fluopyram was more frequently detected in La Rioja. Boscalid, widely used against powdery mildew, was ubiquitous across sampling sites irrespective of region. Most pesticides showed significant dissipation between consecutive application seasons. Nevertheless, boscalid, fluopicolide, metrafenone, tebuconazole, and fluopyram exhibited low average removal rates, indicating a potential for accumulation in vineyard soils. Similarly, the phased-out compounds myclobutanil and dimethomorph displayed slow dissipation dynamics. Preliminary assessment of ecological risks, based on chronic toxicity data for earthworms combined with measured soil concentrations, identified boscalid, carbendazim, and difenoconazole as the most concerning pollutants in the topsoil layer. A prioritization index integrating occurrence frequency, median concentrations, and chronic toxicity highlights a subset of fungicides that warrant continued monitoring in vineyard soils.