Pesticides, Including Neonicotinoids, in Drained Wetlands of Iowa's Prairie Pothole Region

Approximately 95 % of nearly 4 million acres of wetlands located in Iowa's portion of the Prairie Pothole Region (Des Moines Landform Region) are currently drained and farmed for row-crop agriculture. Many of these wetland basins are too wet to produce consistent crop yields and too dry to function as ecologically intact wetlands. Little information currently exists that documents what, if any value, drained wetlands may have in terms of water quality, wildlife usage and/or habitat, and key hydrological aspects. A four-year comprehensive study of drained wetlands was carried out from 2011 to 2014 to document the ecological health of these ecosystems, including the measurement of pesticide levels (including neonicotinoids in 2014). Pesticides were found in more than 60 % of samples and the most frequently detected were chloroacetanilide and triazine pesticides and associated degradate products. At times, concentrations of pesticides exceeded aquatic life benchmarks. The neonicotinoid pesticides were also detected frequently with Clothianidin being the most frequently detected (98 % of samples), followed by Thiamethoxam (54 %), and Imidacloprid (48 %). Pesticide concentration levels were then compared to high quality reference wetlands in the same region. Information from this study advances the knowledge of drained wetlands for both conservation and land-use policy related decisions.