Artificial aeration of benthic water is one of the methods of intensifying phosphorus bonding with bottom sediments. The purpose of this paper was to evaluate changes in contents of phosphorus and some selected metals in the bottom sediments of Lake Starzyc in relation to changes occurring in some selected quality parameters for the benthic water. During the research, the lake water was aerated with a pulverizing aerator. The research was conducted in years 2005, 2006 and 2009. Water and bottom sediment were sampled in seven spots located uniformly throughout the water surface, the inflow area and the area of lake water outflow to the Krąpiel River. The bottom sediments were analysed for the general content of P, Ca, Mg and K, while the water samples were tested for pH and the levels of phosphate phosphorus (P-PO4). TP content in bottom sediments of Lake Starzyc decreased only in the inflow area (by a mean of 43%) in the period covered by the research. Additionally, a gradual decrease of P-PO4 concentration (by a mean of 42%) in benthic water was recorded in that period as well as the decrease in content of Ca, Mg and K in bottom sediments. Results from the analysed metal content show that Ca content was most stable and decreased by a mean of 21% whereas for Mg and K contents the difference was 64% and 56% respectively. The horizontal variability in the content of the analysed elements was found in bottom sediments collected from various zones of the lake. The lowest content wasfound in sediment material collected from the outflow zone of water to the Krąpiel River, and the highest content was recorded in the watercourse supply zone. The greatest variability was observed for the content of  Ca and K – on average it was six times higher in the water inflow zone from drainage ditches as compared to the content in the runoff zone. Throughout the period covered by the research bottom sediments comprised the indigenous source of phosphorus for Lake Starzyc waters.

19.4.2014