Spatial and seasonal distribution of nutrients in the estuarine system of the Pregolya River and the adjacent area of the Baltic Sea
- DOI
- 10.5922/vestniknat-2025-3-7
- Pages
- 99-115
Abstract
Seasonal and spatial variations in the content of biogenic elements (mineral forms of nitrogen and phosphorus) are presented for the estuarine system of the Pregolya River (Kaliningrad Sea Canal, Kaliningrad Bay) and the coastal zone of the Baltic Sea in 2024. Their seasonal dynamics were characterized by maxima during the high-water period. Minima were observed in spring and summer during water “blooming” against the background of intense water warming. Spatial distribution was characterized by the highest nitrogen and phosphorus concentrations in the estuarine zone, where the Pregolya River inflow occurs. Episodic pollution exceeding the maximum permissible concentrations for ammonium and nitrite nitrogen was recorded in the eastern section of the Kaliningrad Sea Canal, including the area near the Kaliningrad wastewater treatment plant outlets. In winter, concentrations of mineral nitrogen and phosphorus corresponded to a potentially hypertrophic level according to the classification for the Baltic Sea waters, which manifests in the high biological productivity of the Pregolya estuarine system. An increase in phosphorus during summer under low nitrogen concentrations creates conditions for the development of cyanobacteria and water “blooming.” The inflow of biogenic substances through the marine strait increases their concentrations in the coastal zone and contributes to the eutrophication of this part of the Baltic Sea.