The role of a lowland reservoir in the transport of micropollutants, nutrients and the suspended particulate matter along the river continuum

The water and sediment samples from the Sulejow Reservoir and Pilica River (Central Poland) were analysed for nutrients: total phosphorus (TP), total nitrogen (TN) and the suspended particulate matter (SPM) and dioxin-like PCBs (dl-PCBs) concentration. Dl-PCBs were detected in sediments from all seven sampling locations with mean concentrations of 14.29 ng kg⁻¹ dry weight (d.w.). The lowest concentration was recorded in the sediment collected below the Sulejow Reservoir (PR5; 2.92 ng kg⁻¹ d.w.) and the highest in the sample collected from the mouth section of the Pilica River (PR7; 26.30 ng kg⁻¹ d.w.). The 29% reduction of the total dl-PCBs concentration – from 9.21 ng kg⁻¹ d.w. in the middle section to 6.54 ng kg⁻¹ d.w. in the dam section of the Sulejow Reservoir – demonstrated the hydraulic transport and deposition of measured pollutants in the reservoir's sediments. The results obtained also revealed the reduction of nutrients and the SPM concentrations. A 45% reduction of SPM, 28% reduction of TP and 34% of TN was observed between the water inflow and outflow from the Sulejow Reservoir.