Assessing acetamiprid and chlorpyrifos pesticide concentrations in water and sediments across macadamia orchard and communal area small reservoirs

Abstract

Pesticides are well known for their persistence in the environment their slow degradation and high toxicity. Aquatic environments, while not the target of many pesticide applications, often receive these chemicals from their catchments through runoff dynamics. Here, we assessed pesticide concentrations of acetamiprid and chlorpyrifos in water and sediment across macadamia orchard and communal area reservoirs in the Levubu area, South Africa, using liquid chromatography tandem mass spectrometry. Analysis of acetamiprid and chlorpyrifos associated with sediments in macadamia orchard reservoirs revealed mean pesticide concentrations of 14.48 µg L−1 and 5.67 µg L−1, respectively, whereas, in communal area reservoirs both pesticides were not detected. Acetamiprid was not detected across reservoir water, whereas the mean pesticide concentration of chlorpyrifos of 6.51 µg L−1 (macadamia orchard) and 0.13 µg L−1 (communal area) were detected. Significant differences were observed for chlorpyrifos concentrations in water samples between macadamia orchard and communal area reservoirs, whereas acetamiprid and chlorpyrifos indicated non-significant differences in sediments. The results indicate that macadamia orchard reservoirs are highly contaminated by acetamiprid and chlorpyrifos. Consequently, these pesticides can alter water quality and ecosystem functioning by reducing species diversity, adjusting community structure, altering energy flow and nutrient recycling.