Neonicotinoid insecticides cause adverse effects on nontarget organisms, but more information about their occurrence in surface and groundwater is needed across a range of land uses. Sixty-five sites in Minnesota, USA, representing rivers, streams, lakes, groundwater, and treated wastewater, were monitored via collection of 157 water samples to determine variability in spatiotemporal neonicotinoid concentrations. The data were used to assess relations to land use, hydrogeologic condition, and potential effects on aquatic life. Total neonicotinoid concentrations were 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 (detection frequency = 100%) and imidacloprid most often in urban waters (detection frequency = 97%). The seasonal trend of neonicotinoid concentrations in rivers, streams, and lakes showed that their highest concentrations coincided with spring planting and elevated streamflow. Consistently low neonicotinoid concentrations were found in shallow groundwater in agricultural regions (<1.2–16 ng/L, median = 1.4 ng/L). Treated municipal wastewater had the highest concentrations across all hydrologic compartments (12–48 ng/L, median = 19 ng/L), but neonicotinoid loads from rivers and streams (median = 4100 mg/d) were greater than in treated wastewater (700 mg/d). No samples exceeded acute aquatic-life benchmarks for individual neonicotinoids, whereas 10% of samples exceeded a chronic benchmark for neonicotinoid mixtures. Although 62% of samples contained 2 or more neonicotinoids, the observed concentrations suggest there were low acute and potential chronic risks to aquatic life. This the first study of its size in Minnesota and is critical to better understanding the drivers of wide-scale environmental contamination by neonicotinoids where urban, agricultural, and undeveloped lands are present. Environ Toxicol Chem 2021;40:1017–1033.
Bibliographical noteFunding Information:
The present study was funded by the Minnesota Environmental and Natural Resources Trust Fund as recommended by the Legislative and Citizen Commission on Minnesota Resources. Thanks to J. Manske and Ramsey County Public Works for lake sampling assistance and plankton enumeration, J. Barry of the Minnesota Department of Natural Resources and the County Geologic Atlas program for the collection and water chemistry measurements of groundwater samples, and M. Langevin (International Water Institute), O. Tedrow (Vermillion Community College), and A. Dingmann (Minnesota Pollution Control Agency) in addition to the Minnesota Department of Agriculture for assisting in the collection of river and stream samples. M. Pillsbury of the Analytical Biochemistry laboratory at the University of Minnesota Masonic Cancer Center is thanked for assistance with LC-MS/MS analysis and data interpretation.
© 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC
- Aquatic life
- Environmental monitoring
PubMed: MeSH publication types
- Journal Article