For decades, both nitrogen stabilizers and herbicide safeners have been used to improve corn production in the U.S. Nitrogen stabilizers (<i>e.g., </i>nitrapyrin) are co-applied with fertilizers during both spring and fall. These stabilizers inhibit nitrification in the soil, keeping fertilizer nitrogen in the ammonium form. This has the potential to benefit corn yields and improve water quality by decreasing leaching of nitrate off site. The dichloracetamide safeners (<i>e.g., </i>dichlormid, benoxacor, and AD-67) are co-applied with herbicides to protect the crop from herbicide toxicity. There are minimal data in the literature focused on either stabilizer or safener usage, environmental exposure, or potential ecological effects. This study focused on one of these research gaps: environmental exposure in streams. Eleven streams in Iowa and two streams in Illinois were sampled at varying frequency from spring 2016 through early summer 2017. Six sites were strategically selected to have hydrologic-based sampling (i.e., sampling storm runoff), while other sites were sampled on a fixed schedule (bi-weekly or monthly). Water samples were processed via solid-phase extraction (SPE) and analyzed using GC/MS. Nitrapyrin was detected year round (42% of water samples). To date, the maximum concentration detected was 1200 ng/L (November 2016). All three safeners were detected (maximum concentrations ranged from 42 to 190 ng/L), but benoxacor was the most frequently detected safener (24% of water samples). For both nitrapyin and the safeners, detections and concentrations appear to be driven by a combination of chemical use and precipitation events. Nitrapyrin results from this study are being used to conduct ecological studies that will address the potential impacts nitrapyrin could have on non-target organisms. In addition, off-site transport and seasonality data from this study could be used to increase stabilizer and safener retention in soils. This would benefit land managers and could reduce environmental exposure.

Assessing seasonal off-field transport of understudied agricultural chemicals to Midwest streams: The nitrogen stabilizer compound, nitrapyrin, and three dichloroacetamide herbicide safeners

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.