Abstract
Urban river is the object of very dynamic hydrochemical changes. It was decided to trace the variability of physicochemical elements within 24-hour. One of the rivers in ŁÓdŹ – Olechówka – was selected for research, where, having knowledge from previous research, two measurement-control points were established: first located in the middle course of the river (on its quasi-natural fragment), second at its mouth to the recipient. Between these points, the Olechówka River catchment gains significantly on urbanization. A measurement series during 24-hour was carried out at each of the points, during which in situ measurements Q, T, pH, SEC and O2 were taken every 1 hour and water samples were taken for the analytical determinations NO3-, PO43-, NH4+, TN, TP and Susp. With relatively stable hydrological conditions, a twenty-four hour cycle of changes in nutrient concentrations was observed, whose maxima occur during the night hours.
Highlights
Rivers flows in an urban area are generally an integral part of the city's drainage system
During the research period at the mcp and the time preceding them by 25 days, which resulted from the time of water inflow from the spring area to Zygmunta Street (ZM), not observed in the precipitation stations located in the catchment and its immediate vicinity (Fig. 1) intensive precipitation which could have causes flood (Fig. 2)
Wilcoxon matched-pairs test indicated that statistically significant differences (p < 0.05) between ZM and Podmokła Street (PD) occur in the case of standardized electrolytic conductivity (SEC), O2, total nitrogen (TN), NO3, PO43– and NH4+
Summary
Rivers flows in an urban area are generally an integral part of the city's drainage system. Incorporation rivers into the sewage system causes that pollutions deposited in the catchment with rainfall, dry deposit or flowing out with drainage systems from the drained soil profile flow into the river. These additional functions clearly burden urban rivers, making them a form far removed from its natural characters. They become practically, in every aspect their hydrological and hydrochemical characteristics, the object of very dynamic transformations and processes. The biggest differences are in the case of total phosphorus, NO3–, dissolved oxygen, water temperature, SEC or pH [6, 7]
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