ОЦІНКА НАВАНТАЖЕННЯ БІОГЕННИМИ ЕЛЕМЕНТАМИ БАСЕЙНУ Р. СУЛА ВІД ТОЧКОВИХ ТА ДИФУЗНИХ ДЖЕРЕЛ

Abstract

Excessive supply of nutrients, phosphorous and nitrogen, to water bodies leads to their eutrophication and other adverse natural processes in aquatic ecosystems. The Sulynska Bay, where the Sula River discharges, has been suffering from severe eutrophication and fish mortality. This is probably due to the high nutrient load in the Sula River basin. However, the dominant approach in Ukraine, which took into account only point sources, did not allow estimating the actual volumes of nutrient inputs to water bodies. A calculation method has been applied in the article for determining the nutrient load of the Sula basin, which takes into account the inputs from point and diffuse sources of pollution. The method applied enabled to establish that the emission in the Sula basin is 921 tons per year or 0.05 tons per km2 for nitrogen and 313 tons per year or 0.017 tons per km2 for phosphorous. However, due to natural processes (primarily nitrification-denitrification and sedimentation), some nutrients are retained in the basin and do not enter water bodies. Thus, it was calculated that 273 tons per year nitrogen and 135 tons per year phosphorous enter the Sula directly. The main nutrient sources are not point sources of pollution, but rather inputs from arable lands (96 tons per year for nitrogen and 95 tons per year for phosphorous) and from the population unconnected to sewage systems (68 tons per year for nitrogen). However, for phosphorous, point sources due to inefficient wastewater treatment facilities also contribute significantly to the nutrient load – 18 tons per year. The study emphasizes the need for an integrated approach to water resources management, which should at least include calculations of the load of catchment with nutrients from diffuse sources of pollution.