Evaluating the Efficiency of Soil Amendments to Mitigate the Leaching of Copper Nanopesticides

As pesticides are necessary to meet current and future agricultural needs, nanopesticides have seen increased use resulting from their more targeted application at lower doses. Copper-based nanopesticides have demonstrated efficacy but there are also concerns about their potential toxicity to aquatic species. This unintended toxic exposure resulting from agricultural runoff containing these nanopesticides can be mitigated through the use of soil amendments. In this study, biochar and chitosan were investigated as soil amendments, as they can bind metals and nutrients; however, there are still open questions about how their effective they are in different soil types and in relation to different nanopesticide exposures. In this study, soil columns and batch sorption experiments were performed to assess the ability of these two amendments to reduce copper and nutrient leaching. The columns were filled with soil from Padilla Bay, an estuary adjacent to agricultural fields, then amended and subsequently dosed with fertilizer and a nanocopper pesticide. The leachates and soil were analyzed for copper using inductively coupled plasma mass spectrometry. The results of the study may provide insight on whether the use of these amendments in the Skagit valley region can assist in the creation of riparian buffer zones to protect the health of the Bay.