SREL Reprint #3838

Anion-mediated pathways in organophosphate degradation in the Oconee River watershed in Georgia

Grace Stamm1,2, Gayatri Basapuram1, Srimanti Duttagupta1, and Avishek Dutta1,3

1Department of Geology, University of Georgia, Athens, GA, 30602, USA
2Department of Physics and Astronomy, University of Georgia, Athens, GA, 30602, USA
3Savannah River Ecological Laboratory, University of Georgia, Aiken, SC, 29802, USA

Abstract: The degradation of organophosphate pesticides in aquatic ecosystems is influenced by various environmental factors. This study investigates the influence of nitrate, sulfate, and phosphate on the degradation of malathion, a commonly used organophosphate pesticide, in the North Oconee River watershed in Georgia. Microcosm experiments were conducted to simulate environmental conditions and assess both microbial and non-microbial transformation pathways. Nitrate, sulfate, and phosphate were found to enhance malathion degradation through microbially mediated oxidative and hydrolytic pathways. The presence of mercuric chloride, which suppressed microbial activity, resulted in slower degradation rates across all conditions, underscoring the pivotal role of microbial communities in pesticide transformation. Non-targeted analyses identified key degradation products, including malaoxon, succinic acid, and diethyl succinate, primarily under nitrate and sulfate conditions, supporting the involvement of these anions in the degradation process. These findings highlight the complex interactions between nutrient dynamics and pesticide persistence, offering valuable insights for sustainable water management and pollution control in agro-impacted freshwater systems.

Keywords: Malathion; Water quality; Degradation; Anion-mediated transformation; Microbial inhibition

SREL Reprint #3838

Stamm, G., G. Basapuram, S. Duttagupta, and A. Dutta. 2025. Anion-mediated pathways in organophosphate degradation in the Oconee River watershed in Georgia. Emerging Contaminants 11(100542).

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).