University of Nebraska-Lincoln
Pesticide application is important to the growing agricultural sector as the demand for production increases. However, the use of these agrochemicals brings potential environmental contamination to water resources. Neonicotinoids are a class of insecticides that may be harmful to critical pollinators such as honey bees and monarch butterflies. Recently neonicotinoids have been detected in surface water in the Midwest. Therefore, the objective of this study was to examine the impact of neonicotinoid pesticides on nitrogen removal in floating treatment wetlands along with quantifying pesticide removal potential in these ecosystems. A mesocosm experiment evaluated three treatments (1. Pesticide enriched water without floating treatment wetlands, 2. Floating treatment wetland with pesticides, 3. Floating treatment wetland without pesticides) in replicates of three over a 21 day period. Grab water quality samples were collected and evaluated for pesticide concentrations using LC MS/MS analysis and nutrient concentrations on an AQ300. Samples were evaluated for neonicotinoid species clothianidin, imidacloprid, and thiamethoxam. Additionally, qPCR was performed on water samples to detect pesticide effects on microbial communities. Reduced neonicotinoid concentrations in mesocosms with floating treatment wetlands suggest a potential for pesticide removal. Preliminary results indicate that neonicotinoid pesticides may enhance nitrate removal in floating treatment wetland systems. This study has direct implications on how pesticides and nutrients are removed in complex water chemistry scenarios in agroecosystems. Results are being used to determine placement and kinetic removal rates of pesticides and nutrients for floating treatment wetlands.