Fate and Transport of Polar Organic Micropollutants in Soil–Plant Systems Quantified by Mass Balance using Laboratory-Scale Lysimeters

Abstract Irrigation with reclaimed water can mitigate water scarcity but may also introduce polar organic micropollutants (OMPs) into agricultural systems. As these compounds are frequently detected in treated wastewater and aquatic environments, this study investigated their environmental fate and transport in the vadose zone, with emphasis on processes in an unsaturated soil–plant system. Spinach was cultivated in laboratory-scale lysimeters irrigated with spiked water, followed by leaching with artificial rainwater. A mass-balance approach was used to quantify the relative contributions of plant uptake, soil retention, leaching, and transformation. Across the fourteen investigated OMPs, soil retention was the dominant process for three substances, leaching for five, and transformation for three, while the remaining compounds showed mixed behavior dominated by leaching and transformation. Trifluoromethanesulfonate exhibited distinctly higher plant uptake than the other OMPs; however, plant uptake contributed only marginally to overall mass balances. These results provide process-based insight into the fate of polar OMPs in soil–plant systems and highlight the potential for rapid leaching of polar OMPs to groundwater. The findings contribute to improved assessment of contaminant transport and support risk management of agricultural water reuse.