Neonicotinoid pesticide and nitrate mixture removal and persistence in floating treatment wetlands. Issue 6 (17th October 2022)

• Record Type: Journal Article
• Authors: Lindgren, Julia K.; Messer, Tiffany L.; Miller, Daniel N.; Snow, Daniel D.; Franti, Thomas G.
• Is Part Of: Journal of Environmental Quality. Volume 51:Issue 6(2022)
• Page Start: 1246
• Page End: 1258
• Publication Date: 2022-10-17
• Subjects: Agricultural ecology -- Periodicals; Environmental engineering -- Periodicals; Pollution -- Periodicals; 630
• DOI: 10.1002/jeq2.20411
• Languages: English
• ISSNs: 0047-2425

Abstract

Abstract: Mesocosm and microcosm experiments were conducted to explore the applicability of floating treatment wetlands (FTWs), an ecologically based management technology, to remove neonicotinoid insecticides and nitrate from surface water. The mesocosm experiment evaluated three treatments in triplicate over a 21‐d period. Floating treatment wetland mesocosms completely removed nitrate‐N over the course of the experiment even when neonicotinoid insecticides were present. At the completion of the experiment, 79.6% of imidacloprid and degradation byproducts and 68.3% of thiamethoxam and degradation byproducts were accounted for in the water column. Approximately 3% of imidacloprid and degradation byproducts and 5.0% of thiamethoxam and degradation byproducts were observed in above‐surface biomass, while ∼24% of imidacloprid and degradation byproducts, particularly desnitro imidacloprid, and <0.1% of thiamethoxam and degradation byproducts were found in the below surface biomass. Further, 1 yr after the experiments, imidacloprid, thiamethoxam, and degradation byproducts persisted in biomass but at lower concentrations in both the above‐ and below‐surface biomass. Comparing the microbial communities of mature FTWs grown in the presence and absence of neonicotinoids, water column samples had similar low abundances of nitrifying Archaeal and bacterial amoA genes (below detection to 10 4 ml −1 ) and denitrifying bacterial nirK, nirS, and nosZ genes (below detection to 10 5 ml −1 ). Follow‐up laboratory incubations found the highest denitrification potential activities in FTW plant roots compared with water column samples, and there was no effect of neonicotinoid addition (100 ng L −1 ) on potential denitrification activity. Based on these findings, (a) FTWs remove neonicotinoids from surface water through biomass incorporation, (b) neonicotinoids persist in biomass long‐term (>1 yr after exposure), and (c) neonicotinoids do not adversely affect nitrate‐N removal via microbial denitrification. Core Ideas: Neonicotinoid and byproducts were present in wetland biomass 21 d after exposure. Neonicotinoid and byproducts persisted in biomass 1 yr after exposure. Neonicotinoid exposure did not adversely affect nitrate‐N removal via denitrification.