Progressing urbanization potentially generates more pollution sources such as waste, industrial or municipal sewage, which may contain hazardous inorganic pollutants e.g. metal ions and their compounds. Urbanization is bad for soils because it is responsible for a growing share of impermeable surfaces such as pavements, car parks, housing developments and public buildings. The hardened (impermeable) surface is exposed to intensive surface runoff during rain, so that pollutants are transported through a storm drainage system directly to surface waters. The aim of this study was to determine the effect of metals contained in rainwater discharged from subcatchments of various land use types on the quality of surface waters (the Cybina River and Antoninek Reservoir) in the city of Poznań, as well as to check whether the metal content in rainwater effluents depends on the relief and character of the immediate catchment. The investigations were conducted in 2009, along the lower section of the Cybina River. Water samples from the river and the reservoir were collected parallel to the collection of rain water samples. Water and sewage samples were collected 15 times a year. Analyses were conducted on 5 selected catchments (with different land uses) drained by a storm water drainage system discharging rainwater to the Cybina River and Antoninek Reservoir. Water was collected from 13 sampling points (5 of which were sewer outlets and 8 were situated on the river or the reservoir above and below the sewage discharge point). Higher concentrations of all the tested elements were recorded in rainwater than in water samples from the river or the reservoir. The Canonical Variate Analysis (CVA) model presenting differences between water concentrations of Cu, Zn, Cd, Pb and Fe and environmental variables (rainfall intensity measured on a four-point scale, location divided into industrial areas, multi- and single-family housing, as well as the position of sewage discharge points, i.e. to the river on the reservoir) showed elevated concentrations of these elements, especially in water collected directly from the storm water sewer. Elevated metal concentrations in storm system effluents did not have a significant effect on the content of these pollutants in the river or the reservoir, which could have been caused by the intensive immobilization of elemental ions in bottom deposits followed by the uptake of metals by aquatic organisms, mainly plants.

19.3.2014