Accumulation of Trace Organic Compounds and Antibiotic Resistance Genes in Plants Irrigated with Reclaimed Water

Abstract

Treated wastewater is a viable alternative to conventional irrigation water, particularly in arid areas, but it is imperative to understand potential environmental or public health risks associated with this practice, e.g., accumulation of trace organic compounds (TOrCs) in the edible portions of food crops. This study monitors the concentrations of 13 TOrCs in wastewater treated with ultrafiltration (UF) in soils irrigated with these waters. The non-edible and edible portions of spinach and tomato plants grown in soil-based systems irrigated with reclaimed water were analyzed. Two soil-based growth cycles have been completed, where samples have been analyzed for TOrCs uptake. Preliminary data show that under ambient conditions, TOrCs uptake is generally limited to the non-edible portions of tomato plants (9 of 13 compounds detected in soil, 6 compounds in roots, 5 compounds in leaves, and 0 compounds in fruit), and only one compound was detected in spinach leaves (sucralose at 105 ng/g). Even when spiked at 10-50x ambient concentrations, only low levels of benzotriazole, meprobamate, and sucralose were detected in tomato fruit, and this was partially mitigated by sequential irrigation (i.e., reclaimed water followed by tap water at fruiting stage). This study can aid in evaluating the feasibility of widespread implementation of water reuse in agricultural applications, including quantitative information critical to assessing risks associated with TOrCs and antibiotic resistance genes (ARGs) exposure.