Abstract
Municipal wastewater is a known point source of organic contaminants, including pharmaceuticals and neonicotinoid insecticides. Emergent aquatic insects can provide a direct aquatic-to-terrestrial contaminant transfer route to the food web, with implications for terrestrial food web dispersal of wastewater-derived organic contaminants. We quantified 17 target pharmaceuticals and insecticides (log Kow: −1.43 to 4.75) in surface water, fish, aquatic insects, and web-building riparian spiders at a wastewater effluent-dominated stream in eastern Iowa, USA. Two neonicotinoids, imidacloprid and clothianidin, had spider tissue concentrations of 8.9–84 ng/g and 1.2–11 ng/g, respectively. The imidacloprid/clothianidin ratios in spider tissues were reflective of the concentration ratios in the effluent-dominated streamwater and opposite of nearby agriculturally dominated waters. In contrast, no pharmaceuticals were detectable in the riparian spiders; however, only pharmaceuticals were present in both fish and aquatic insects (1.1–11 ng/g and 5.9–51 ng/g, respectively). Neonicotinoids are not predicted to enter aquatic food webs based on their log Kowand bioconcentration factor values; therefore, an implication of this study is to warrant caution when using traditional bioaccumulation models for polar hydrophilic contaminants. This work provides further evidence that neonicotinoids undergo trophic transfer and represents the initial measurements, implicating such a transfer from effluent-dominated streams into terrestrial food webs. While this study emphasizes field-relevant observations, it is limited by environmental variability, including uncertainties in the biomass of emergent insects that likely contribute to spider diets. Future research could investigate contaminant metabolites within individual organisms or use complementary techniques to better understand the underlying mechanisms.
| Original language | English |
|---|---|
| Pages (from-to) | 457-467 |
| Number of pages | 11 |
| Journal | ACS Environmental Au |
| Volume | 5 |
| Issue number | 5 |
| DOIs | |
| State | Published - 2025 |
| Externally published | Yes |
Funding
This work was supported by grants from the National Science Foundation #1844720 and #1803197 and from programmatic support from the U.S. Geological Survey’s Environmental Health Program under the Ecosystems Mission Area. A.L.M. was supported by University of Iowa Graduate School Fellowships and the Dr Arthur R. Giaquinta Memorial Scholarship. G.H.L. acknowledges the support of the Environmental Health Sciences Research Center (P30 ES005605) for providing a collaborative research environment. We thank Dr. Emily Bernhardt of Duke University for her support and expertise formulating this project, graduate student Jasmine Parham of Duke University for help with spider sample collection and identification, Shannon Meppelink of the USGS for her assistance conducting instream hydrologic measurements, and Drew Lammers and Mark Farrier from the North Liberty Wastewater Treatment Plant. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government or the authors.
Keywords
- bioaccumulation
- effluent-dominated streams
- food webs
- neonicotinoids
- pharmaceuticals
- riparian spiders
- wastewater