Mini Grant: Estimation of Watershed Glyphosate Exports in Karst Landscapes

  • Hobbs, Shakira (PI)

Grants and Contracts Details


Significance: Glyphosate, an herbicide, and its breakdown product aminomethylphosphonic acid (AMPA) enter waterways via run-off and are more mobile and persistent in aquatic environments [1]. In addition, glyphosate has been classified as a probable carcinogenic by the World Health Organization [3, 4] and AMPA potentially leads to cancer as well [5, 6]. Concern about impacts to the environment and human health continues to grow and application rates increase with production of glyphosate-resistant crops for more efficient weed control in agriculture, globally [4]. In 2012, approximately 127,000 tons of glyphosate were applied in the United States, and 700,000 tons were applied worldwide [7]. Trace levels of glyphosate have been found in the urine of 60-80% of the sample population of 114 people in the United States [8]. The rapid growth of glyphosate use has certainly increased exposure for those that use the herbicide and for individuals that do not come into direct contact with the herbicide. For example, people who live in karst regions may be more at risk to exposures of glyphosate and AMPA through contamination of water sources. Karst landscapes are areas where limestone is eroded, producing fissures and sinkholes where water is quickly directed and concentrated in subsurface conduits (Figure 1). Output concentrations of glyphosate in groundwater in Kentucky correlate to inputs in agricultural systems with a karst landscape [9]. Agricultural and residential run-off in karst water may lead to higher exposure rates for humans residing in the surrounding regions. With growing water and food production demands, and rapidly increasing application rates of glyphosate, it is imperative to investigate and understand glyphosate in karst regions. Vision: For this proposal, we intend to collect water samples from the Cane Run and Royal Springs Watershed and Camden Creek Watershed to provide data to estimate glyphosate transport in water resources, based on applications rates, and estimate environmental and health impacts. This work will provide preliminary data for submitting a proposal to the United States Department of Agriculture- National Institute of Food and Agriculture (USDA-AFRI). Results from this work will inform steps to be taken in advancing the water quality and health of the state and can serve as a benchmark of innovation for modeling pesticide transport in water resources for the Appalachian Region. Prior work in this research area consisted of collaborating with University of Belize along with the Belize Department of Environment and Ministry of Health collecting water samples from The New River and Belize River Watersheds; both of these watersheds are in karst systems. We are in the process of modeling the fate and transport on a watershed scale using Soil and Water Assessment Tool (SWAT). Preliminary results from this work show that simulated concentrations of nitrates, which is used as an indicator of pesticides present, were much lower than observed concentrations. We recently received access to historical data from our collaborators and to equipment to detect glyphosate. This will assist in further calibration of the model and tests for robustness.
Effective start/end date2/1/203/31/20


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