Analysis of Selected Nutrient Contents in Bottom Sediments of the Ostrowy Water Reservoir using the GIS System

The aim of the study was to evaluate the contents of phosphorus and nitrogen in bottom sediments of the Ostrowy water reservoir. Furthermore, concentrations of aluminium, iron, organic matter were determined and the depth was measured. The evaluation was made using spatial modelling to obtain spatial distributions of the elements studied. Aluminium and nitrogen concentrations were classified according to the Persaud criteria. An attempt was also made to determine the possible relationships between nitrogen and phosphorus, and the content of organic matter, iron and aluminium in the material studied. Bottom sediment samples were collected based on a regular measurement grid from 31 points in the area of the Ostrowy water reservoir. The material was subjected to laboratory analysis, with the contents of elements tested ranging from 0.25 to 9.76 g/kg for total nitrogen, 0.04 to 4.50 g/kg for total phosphorus, 0.48 to 31.40% for organic matter, 0.57 to 12.64 g/kg for aluminium, and 1.70 to 30.70 g/kg for iron. Based on the Persaud classification, the major area of the reservoir is characterized by moderate and high risks resulting from the nitrogen content and low and moderate risk due to the presence of phosphorus. The correlations were also examined between organic matter and total nitrogen (R2 = 0.82), total nitrogen and Fe (R2 = 0.79), total nitrogen and Al (R2 = 0.74), organic matter and Fe (R2 = 0.82), organic matter and Al (R2 = 0.79), total phosphorus and Fe (R2 = 0.88), and total phosphorus and Al (R2 = 0.74). The GIS tools used to generate spatial distributions have proven to be extremely useful in environmental research. Using geoinformation, maps of spatial distributions of the elements studied were generated (the method of interpolation of inverse distance weighted was used). Bottom sediments of water reservoir in Ostrowy are characterized by higher contents of nitrogen and phosphorus in bottom part and lower in northern part. The distributions made it possible to accurately assess the studied area and can be effective in planning of monitoring and reclamation activities in the area of the Ostrowy water reservoir.