Assessing pesticide wet deposition risk within a small agricultural watershed in the Southeastern Coastal Plain (USA)

Abstract

Pesticide volatilization and deposition with precipitation is widely documented and has been connected to adverse ecological impact. Here we describe a 3-yr study of current use and legacy pesticides in event-based rain samples within a 123-ha agricultural watershed. Crops in farm fields were documented quarterly with data used to estimate target compound use. The median number of pesticide detections in samples was 6. The fungicide, chlorothalonil which was used most intensively was detected in nearly all samples. It had the highest mean and peak concentrations with total deposition ≈0.1% of the estimated amount applied. The insecticide endosulfan also had relatively high use with behavior mirroring chlorothalonil. There was strong seasonal variation in concentration and depositional dynamics with the highest values measured during growing seasons. Similar behavior was observed with other compounds detected in rain samples with a general decrease in deposition and mean concentrations as use decreased. Comparison of measured concentrations to values associated with toxic impact on aquatic organisms indicated that chlorothalonil, endosulfan, chlorpyrifos, malathion and atrazine may contribute to adverse impact. The number of samples exceeding risk endpoints ranged from 1 to 77%. The highest value was for endosulfan; however its on-going phase-out is expected to reduce risks. Another finding was that the wet deposition of the herbicide, metolachlor exceeded measured runoff rates in the watershed by 5-fold. The study has demonstrated that localized pesticide wet deposition may present ecological risks and that volatilization and wet deposition is an important pesticide transport pathway at the local scale. Findings point to the need to include wet deposition in assessments of pesticide ecological risk and environmental fate.

Water-quality observations of the San Antonio segment of the Edwards aquifer, Texas, with an emphasis on processes influencing nutrient and pesticide geochemistry and factors affecting aquifer vulnerability, 2010–16

“…The presence of trace concentrations of pesticides in rainfall in this study is consistent with concentrations of pesticides in rainfall in both developed and pristine areas of the United States (Thurman and Cromwell, 2000;Potter and Coffin, 2017). Postapplication losses of pesticides are reported to range from 0.2 to more than 90 percent and are related to many factors, including physical properties of the pesticide and climatic conditions (Van Pul and others, 1999;Barbash, 2007).…”

Pesticides in water sources used for human consumption in the semiarid region of Argentina

“…5). Other authors reported similar behaviors in surface and rainwater [12,67,68]. Concentrations of metolachlor were well below those of glyphosate and atrazine due to its lower use (treated area and field doses): 84% of concentrations were underneath the EU limit of 0.1 µg L −1 .…”

“…Years later, detections in rainwater from the same area decreased due to a reduction in the use of the product [27]. Potter and Coffin [68] concluded that the high volatility of metolachlor would produce wet deposition and estimated it would represent approximately 1% of the applied product, five-fold greater than that mobilized by surface runoff. Vogel et al [12] detected a mean frequency of 83% in rainwater from four basins of the USA.…”

Enantioselectivity in degradation and ecological risk of the chiral pesticide ethiprole

“…About 19.4% of cultivated land and 11.4% of fallow land in China are polluted by heavy metals, nutrients, and organic pollutants such as pesticides and polycyclic aromatic hydrocarbons (Chen, de Sherbinin, Ye, & Shi, ; Rey et al, ; Zhao, Luo, Deng, & Yan, ). Contamination of soil by pesticides is primarily caused by source pollution in cultivated lands and to some extent by nonpoint source pollution due to long‐range atmospheric deposition (Epple, Maguhn, Spitzauer, & Kettrup, ; Potter & Coffin, ). In recent decades, pesticide use in cultivated land grew due to an increase in global food demand.…”

“…caused by source pollution in cultivated lands and to some extent by nonpoint source pollution due to long-range atmospheric deposition (Epple, Maguhn, Spitzauer, & Kettrup, 2002;Potter & Coffin, 2017). In recent decades, pesticide use in cultivated land grew due to an increase in global food demand.…”