Neonicotinoid pesticide and nitrate mixture removal and persistence in floating treatment wetlands

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 104 ml−1) and denitrifying bacterial nirK, nirS, and nosZ genes (below detection to 105 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.

Influence of Four Veterinary Antibiotics on Constructed Treatment Wetland Nitrogen Transformation

“…The use of floating treatment wetlands as potential systems for emerging contaminant treatment is a relatively new concept, and, thus, few studies have assessed the implications of agrochemical introduction to wetland ecosystems and how that may impact nutrient cycling and other environmental health factors. Lindgren et al (2022) evaluated neonicotinoids in constructed floating treatment wetlands, reporting that the pesticide did not significantly affect nitrate reduction in floating wetlands [60]. This result is again consistent with the results from both experiments in our study that little to no influence is observed by agrochemicals until they are observed at elevated levels.…”

“…Changes in NO 3 -N concentrations in the mesocosm experiments were fit to a first-order decay response model [44,[60][61][62][63]. First-order removal rate constants (k) were determined for each treatment in the mesocosm experiments using the following equation:…”

Associations between neonicotinoids and liver function measures in US adults: National Health and Nutrition Examination Survey 2015–2016

“…3 Several studies have found high levels of neonicotinoids in soil samples and water sources around the world. [4][5][6][7][8][9][10][11][12][13] Fruits and vegetables sampled in the United States (US) were found to have more than 90% detectable levels of neonicotinoids. 14,15 High levels of neonicotinoids have also been found in dust samples in China and the US, [16][17][18] air around farmland in Canada, 19 and among Italian household air samples.…”