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Wastewater treatment plants (WWTPs) transmit many chemical contaminants to aquatic environments. Quantitative data on micropollutant emissions via WWTPs are needed for environmental risk assessments and evaluation of mitigation measures. This study compiled published data on substances analysed in effluents from WWTPs in the Baltic Sea region, assessed country related differences in the data sets and estimated micropollutant inputs to the Baltic Sea catchment. Concentration data were found for 1090 substances analysed at 650 WWTPs. Heterogeneity and low number of data points for most substances hindered adequate comparisons of country specific concentrations. Emission estimates were made for the 280 substances analysed in at least five WWTPs in years 2010 to 2019. For selected substances, mass loads were compared to previously published estimations. The study provides data useful for national and Baltic Sea-scale pressure analysis and risk assessments. However, it also highlights the need for broad scope monitoring of micropollutants in wastewater.

Equilibrium sampling devices can be applied to study and monitor the exposure and fate of hydrophobic organic chemicals on a thermodynamic basis. They can be used to determine freely dissolved concentrations and chemical activity ratios and to predict equilibrium partitioning concentrations of hydrophobic organic chemicals in biota lipids. The authors' aim was to assess the equilibrium status of polychlorinated biphenyls (PCBs) in a contaminated lake ecosystem and along its discharge course using equilibrium sampling devices for measurements in sediment and water and by also analyzing biota. The authors used equilibrium sampling devices (silicone rubber and polyethylene [PE]) to determine freely dissolved concentrations and chemical activities of PCBs in the water column and sediment porewater and calculated for both phases the corresponding equilibrium concentrations and chemical activities in model lipids. Overall, the studied ecosystem appeared to be in disequilibrium for the studied phases: sediment, water, and biota. Chemical activities of PCBs were higher in sediment than in water, which implies that the sediment functioned as a partitioning source of PCBs and that net diffusion occurred from the sediment to the water column. Measured lipid-normalized PCB concentrations in biota were generally below equilibrium lipid concentrations relative to the sediment (CLip ⇌Sed ) or water (CLip ⇌W ), indicating that PCB levels in the organisms were below the maximum partitioning levels. The present study shows the application versatility of equilibrium sampling devices in the field and facilitates a thermodynamic understanding of exposure and fate of PCBs in a contaminated lake and its discharge course. Environ Toxicol Chem 2015;34:2463-2474. © 2015 SETAC.