Phosphate dynamics in the drinking water catchment area of the Dobromierz Reservoir

摘要

Surface waters polluted by nutrients from agricultural sources or sewage can change their trophic state into high productive and rich in nutrient content. In particular, phosphates are often regarded as the main hazard because they may activate eutrophication. This article presents the studies conducted in order to understand better the process of phosphate build-up in surface waters of Strzegomka River at the inflow and outflow from Dobromierz Reservoir, Lower Silesia, Poland, Central Europe. The Dobromierz Reservoir is the source of drinking water for over 25,000 people. Daily changes in phosphate concentrations were analysed during the hydrological year XI 2000-X 2001 and in the long-term monthly changes over the period of 15years (2000-2014). Phosphate concentrations monitored in Strzegomka River showed great changeability. Peak phosphate concentrations reaching 1.70mg/L were noted in the catchment in the autumn of the hydrological year 2000/2001. The mean concentration of phosphates on the inflow to the Dobromierz Reservoir (2000-2014) was 0.33mg/L. No statistically significant decreasing trends were detected for phosphorus compounds concentrations at the inflow of the Dobromierz Reservoir. This means that the problems with the quality of water collected from the reservoir and with the treatment thereof are continuing. Additionally, the research results indicated that treatment processes take place during water flow through Dobromierz Reservoir. A significant reduction of phosphate concentrations up to 66% was confirmed and the possibility of eutrophication of the Dobromierz Reservoir was pointed out. The analysis shows that the most important factors influencing P-PO4 loads in the Strzegomka River are precipitation and thus also water discharge.