Wpływ naturalnych i sztucznych spiętrzeń wody na redukcję stężeń azotu w ciekach powierzchniowych na przykładzie zlewni Kocinki (Wyżyna Wieluńska)

Groundwater and surface waters are a common, inseparable resource of drinking water. The agricultural Kocinka River catchment in southern Poland is among the case studies within the BONUS - Soils2Sea project (Reducing of nutrient loadings from agricultural soils to the Baltic Sea via groundwater and streams). The study is oriented on exploring the possibilities of reducing nitrates. High concentrations of nitrates are observed in groundwater of the Upper Jurassic Major Groundwater Reservoir No. 326, in which the Kocinka catchment area is located. Previous studies in this area failed to determine whether there is denitrification of nitrates in groundwater. The aim of the study is to investigate the significance of denitrification processes in surface water for the quality of waters in catchments. The influence of artificial and natural water reservoirs on nitrogen removal in the catchment was evaluated. Samples and measurements were taken with particular attention to sites upstream and downstream of the reservoirs. Concentrations of nitrates, conductivity (EC), pH, dissolved oxygen and isotope ratios of oxygen and nitrogen in nitrates were determined in selected locations. The results indicate that nitrate reduction potential differs between the reservoirs. Especially fish ponds show high potential to remove nitrates, depending on seasonal variability.