Evaluating point source pesticide contamination via sprayer washing water dispersal: A northern Italian vineyard area case study.

Wastewater contaminated by plant protection products (PPP) from sprayer cleaning operations must be properly managed and disposed of, as it could represent a point source of environmental PPP pollution and pose risks to non-target organisms. Three conventionally and two organically managed farms in hilly vineyards of North-West Italy engaged in a participatory activity for sampling sprayer washing and resultant water. In total 52 samples of wash water (internal and external) were collected during two agricultural seasons and analyzed for six organic pesticides and metallic Cu. PPP concentrations in water collected after internal washing were up to 37.9 times higher than in water collected after external washing. Concentrations in water after external washing were surprisingly high. This may be explained by the characteristics of the sprayers, but also by farmers failing to comply with good practices during PPP use. To evaluate the possible impact on the aquatic environment of dispersal of wash water into a water body, the FOCUS "Stream" approach was followed. The concentrations thus estimated were almost always higher than the environmental quality standard for surface waters but below the toxicological endpoints for fish and Daphnia magna. With reference to the Italian guidelines for waste classification, only one sample would be classified as ecotoxicological hazardous waste and need to be properly managed. In conclusion, due to the nature of contamination, which is point source but diffuse in the territory, analytical data confirms the need for additional joint efforts to improve awareness in managing wastewater containing PPP and to decrease the impact of the agricultural sector.