Glyphosate, a broad spectrum, non-selective herbicide, is widely used in agriculture and urban watersheds throughout the U.S. According to National Agriculture Statistics Service, glyphosate use in agriculture in the state of Ohio has increased over 20 times from 150 metric tons in 1990 to 3100 metric tons in 2015. While generally considered nontoxic to aquatic organisms at these levels, some research has indicated that glyphosate could play a role in increasing loading of phosphorous to surface water by out-competing phosphate for sorption sites in soil. Apart from the Great Lakes region, detectable concentrations of glyphosate have been found in streams from different parts of the world including the mid-western US, Canada, Argentina, and Switzerland, with concentrations ranging from 0.5 to 70 µg/L. Due to its increasing use throughout the world, and potential ecological risks, new high throughput methods are needed to better understand and characterize runoff patterns in agricultural and suburban watersheds. Hence, we developed a new high throughput analytical method to quantify glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), in environmental samples using ion chromatography coupled to inductively coupled plasma mass spectrometry (IC-ICP-MS). This method requires little sample preparation, no derivatization, and provides high sensitivity (IDL ~5 µg/L) at low cost. We then seasonally monitored these compounds in surface water receiving agricultural run-off in Ohio watersheds from Fall 2018 to Summer 2019. Our preliminary studies have shown detectable levels of glyphosate and AMPA in the tributaries with the concentrations ranging from 4.2 to 15.9 µg/L. This presentation will discuss the seasonal occurrence of glyphosate and AMPA, in the tributaries of Lake Erie basin, more specifically in the Rock Creek and Honey Creek tributaries of the Sandusky River.<br/>

Seasonal changes in glyphosate concentrations in the Lake Erie tributaries using high throughput monitoring with IC-ICP-MS

2019 Fall National Meeting

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