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Artificial aeration of benthic water is a method promoting more intensive phosphorus bonding in bottom sediments. The purpose of this paper was to evaluate changes in the content of phosphorus and some selected metals in the bottom sediments of Starzyc Lake in relation to changes occurring in some quality parameters for the benthic water. During the research, conducted in 2005, 2006 and 2009, the lake water was aerated with a pulverizing aerator. Water and the bottom sediment were sampled in seven sites distributed uniformly throughout the water surface, the inflow area and the area of the lake water outflow to the Krąpiel River. The bottom sediments were analyzed for the total content of P, Ca, Mg and K, while the water samples were tested for pH and the levels of phosphate phosphorus (P-PO4) In the period covered by the research, the TP content in the bottom sediments of Starzyc Lake decreased only in the inflow area (by a mean of 43%). Additionally, a gradual decrease of the P-PO4 concentration (on average by 42%) in the benthic water was recorded in that period as well as a decrease in the content of Ca, Mg and K in the bottom sediments. The results from the analysed metal content show that the Ca content was most stable, decreasing by an average 21%, whereas the difference for the Mg and K content was 64% and 56%, respectively. The horizontal variability in the content of the analysed elements was found in the bottom sediments collected from various zones of the lake. The lowest content was found in the sediment material collected from the outflow zone of water to the Krąpiel River, and the highest one was recorded in the watercourse inflow zone. The highest variability was observed for the content of Ca and K, which on average was six times higher in the water inflow zone from drainage ditches than in the outflow zone. Throughout the research period, the bottom sediments comprised an indigenous source of phosphorus for the Starzyc Lake waters.
The paper presents the impact of pollutants from areas intensively used for agriculture on the quality of shallow groundwater in the drainage basin of Lake Miedwie, which is the main source of potable water for the city of Szczecin. This groundwater, due to the poor insulation against the penetration of contaminants from the surface, is a good indicator of the environmental pressure level from agriculture. The aim of the study was to analyze the chemical composition as well as the pH and electrolytic conductivity of waters of the first Quaternary aquifer in the catchment area of Lake Miedwie, located in the municipality of Warnice, which is characterized by intensive farming. The results indicate that there has been a noticeable improvement over the last ten years in the quality of groundwater, and periodic increases in the levels of certain chemical parameters such as ammonium nitrogen (6.070 mg dm-3), nitrate nitrogen (225.1 mg dm-3), phosphate phosphorus (2.635 mg dm-3) or potassium (452.0 mg dm-3) can be explained by negligence or insufficient knowledge of farmers with respect to manure storage and rational use of mineral fertilizers. Correlation analysis of the sum of chemical parameters regarding conductivity demonstrated a virtually absolute relationship (r=0.948 at p=0.001), confirming a close relationship of groundwater’s chemical parameters with the properties of the physical parameter such as specific electrolytic conductivity. Moreover, it was shown that the specific electrolytic conductivity of groundwater of 8 piezometric intakes tested was mainly shaped by the concentrations of sodium (Na), potassium (K) and magnesium (Mg) for all chemical parameters analyzed.
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