Data Supporting Neonicotinoid Insecticides in Surface Water, Groundwater, and Wastewater across Land Use Gradients and Potential Effects

Abstract

Neonicotinoid insecticides are known to cause adverse effects on non-target organisms, but more information about their occurrence in surface and groundwater is needed across a range of land use. In this study, water samples from across the state of Minnesota, U.S., were analyzed to determine the variability in spatiotemporal neonicotinoid concentrations and their relations to land use, hydrogeologic condition, and to assess potential effects on aquatic life. Sixty-five sites, representing rivers and streams, lakes, groundwater, and treated wastewater were monitored, via collection of 157 water samples. Results showed that total neonicotinoid concentrations were the highest in agricultural watersheds (median = 12 ng/L) followed by urban (2.9 ng/L) and undeveloped watersheds (1.9 ng/L). Clothianidin was most frequently detected in agricultural areas, and imidacloprid was most frequently detected in urban waters. The seasonal trend of neonicotinoid concentrations in rivers, streams, and lakes showed that their highest concentrations coincided with spring planting and elevated streamflow conditions. Consistently low neonicotinoid concentrations were found in shallow groundwater in agricultural regions. Treated municipal wastewater had the highest overall concentrations, however, neonicotinoid loads from rivers and streams (median = 4100 mg/d) were greater than in treated wastewater 700 mg/d). No concentrations exceeded aquatic-life benchmarks, but increasing use and sublethal effects create potential risks, such as toxicity and disrupted development of aquatic insects, to natural and engineered waters. This the first study of its size to document the occurrence of neonicotinoid insecticides in Minnesota and is critical to better understanding the drivers of widescale environmental contamination by neonicotinoids where urban, agricultural, and undeveloped lands are present.