Seasonal dynamics of multiple pollutants across a spectrum of aquatic environments: Insights from long-term diffusive gradients in thin-films (DGT) technique field monitoring

Diffusive Gradients in Thin-films (DGT) can be used as an effective supplement of the water pollutant monitoring. However, long-term application and verification of the DGT technique in nature waters have been limited due to the substantial effort required to compare DGT results with those obtained from grab sampling. This study compared the concentrations of a variety of trace elements and emerging organic contaminants (EOCs) measured using DGT and grab sampling method during long-term in field. The results show that the precision and accuracy of DGT can meet the technical requirements. The concentrations of selected trace elements, EOCs and phosphorus were determined in freshwater systems (six rivers and two lakes) across various cities and seawater systems (two sampling sites in Yancheng) during different seasons. The sources and seasonal variations of these pollutants were analyzed. The results show the concentrations of trace elements in the surface water of Nanjing and Yancheng were in the ranges of 0.010–8.97 and 0.010–47.1 μg L −1 , respectively. While the EOCs in the surface water of Nanjing and Yancheng changed within the range of 0.111–390 and 0.110–207 ng L −1 , respectively. Surface waters in Yancheng expressed lower EOC pollutant concentrations than the surface waters in Nanjing (except for PFOA, PFOS and OPFRs). During summer and autumn, the pollutant concentrations were lower than that during spring and winter (except for pesticides). Concentrations of NH 4 -N, NO 3 -N, and phosphorus were also measured via grab sampling and DGT for water quality assessment. The Predicted No-Effect Concentrations (PNECs) of the target trace elements and EOCs were calculated to evaluate the environmental risks of these substances on aquatic species. The levels of most target detected in this work did not appear to present risks to the aquatic species. However, a few substances showed moderate or high risk.