Heavy metals in sediments of water bodies in the Służew stream catchment (Warsaw area)

The Służew Stream, a 14.9 km long watercourse, is part of an ancient river called Sadurka that starts its course in the Warsaw district of Ochota and flows into the Wilanów Lake. In the 19^th and 20^th centuries, the watercourse received industrial and municipal sewage from Warsaw and its environs, but nowadays only rain and snow meltwater is discharged into the stream. Freshwater sediments of five reservoirs in the catchment area of the Służew Stream - Wilanów Lake, Powsinów Lake, Pond in the Horse Racing area, Lake at Morgi and South Pond in the Wilanów Park - were analysed for the contents of Cr, Cu, Pb, Zn, Ni, Cd and Hg. The following concentrations have been determined: chromium - from 5 to 274 mg/kg, copper - from 5 to 274 mg/kg, lead - from 3 to 310 mg/kg, zinc - from 44 to 1430 mg/kg, nickel - from 3 to 55 mg/kg, cadmium - from 0.3 to 37.3 mg/kg and mercury - from 0.010 to 0.810 mg/kg (Fig. 2-5). The studies have shown that water sediments of Pond in the Horse Racing area, South Pond and Wilanów Lake, supplied by the Służew Stream waters, are characterised by a very high content of heavy metals. In contrast, water sediments of Powsinów Lake and Lake at Morgi, recharged by drainage ditches flowing into the stream, are characterised by much lower concentrations of these elements, but the levels are still much greater than the geochemical background.