EVALUATION OF THE WATER EUTROPHICATION LEVEL OF THE GOCZAŁKOWICE DAM RESERVOIR (POLAND, CENTRAL EUROPE)

<ns3:p>The aim of the research was to assess the state of eutrophication of the Goczałkowice dam reservoirin 2021 and 2022. The Goczałkowice reservoir is located in southern Poland, in Central Europe. Thisreservoir has flood control and water supply functions, therefore the purity of its waters is veryimportant. The reservoir is surrounded by numerous agricultural fields and rural areas withouta sewage system. This significantly contributes to the increase in the fertility of the reservoir water.The samples for algae research were taken during the vegetation season in 2021 and 2022 during 6months from two research points (from May to October) – G 1 and G 2. The assessment of thetrophic state of studied reservoir parts was based on limit values given by Heinonen for the totalphytoplankton biomass and the OECD limit values for chlorophyll a, total phosphorus and totalnitrogen.The results of the research regarding the average size of algae biomass in the reservoir water indicatea prevailing meso-/eutrophic (2.96 mgdm-3 – G 1 and 2.73 mgdm-3 – G 2 in 2021) and eutrophicstate of the water (3.15 mgdm-3 – G 1 and 2.94 mgdm-3 – G 2 in 2022) at the studied sites in bothyears of the research (the boundary values of the phytoplankton biomass for meso- /eutrophy andeutrophy amount to 1.98 mgdm-3 – 3.45 mgdm-3 and 3.45 mgdm-3 – 6.93 mgdm-3 respectively). Thenumerous Cyanobacteria (i.a. Microcystis viridis, Aphanizomenon flos-aquae, Planktothrix agardhii),green algae (i.a. Pediastrum boryanum, Coelastrum microporum) and diatoms (i.a. Aulacoseiragranulata, Nitzschia acicularis and Nitzschia sigmoidea) have been observed in the reservoir water.These taxa are typical for eutrophic waters.High concentrations of total nitrogen (in the range of 0.57 mgdm-3 and 1.6 mgdm-3) and totalphosphorus (between 0.034 mgdm-3 and 0.1 mgdm-3) allowed the reservoir water in the area of thedam to be classified as eutrophic and periodically hypertrophic, especially in the summer (theboundary values of the total phosphorus and total nitrogen concentrations for eutrophy amount to0.035 mgdm-3 – 0.1 mgdm-3 and 0.6 mgdm-3 – 1.5 mgdm-3 respectively). This is particularlydangerous due to the fact that this reservoir is used as a water supply source.</ns3:p>