The current study evaluates the impact of sewage sludge and urban reservoir sediment on changes in total and Toxic Equivalency (TEQ) PCDD/PCDF concentration in soil and phytotoxicity measured using three test species: Lepidium sativum, Sinapis alba, and Sorghum saccharatum, during 5 weeks of Cucurbita pepo L. cv ‘Atena Polka’ (zucchini) cultivation. ‘Atena Polka’ was found to reduce total PCDD/PCDF concentration by 37 % in soil amended with sludge and 32 % in soil treated with sediment from an urban reservoir. The TEQ reduction was almost twofold greater: 68 % in soil amended with sludge and 52 % with urban sediment. Addition of sludge increased root growth inhibition of L. sativum, S. alba and S. saccharatum, from 44 % to 90 %. Observed inhibitions were, however, reduced by ‘Atena Polka’ cultivation, and as high as 32 % promotion in root length was noted. Amendment with urban sediment, in turn, resulted in an initial 1 %–36 % promotion of root growth, while ‘Atena Polka’ cultivation reduced this positive effect by inhibition as high as 26 %. Results demonstrated positive influence of ‘Atena Polka’ on the phytotoxicity alleviation and mitigation of total and TEQ PCDD/PCDF concentrations in soil treated with bio-solids from sewage sludge and an urban reservoir.

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.