Comprehensive studies of river mouths flowing into the Onezhskiy Bay of the White Sea

Abstract

Comprehensive oceanological studies depending on the tidal phase are important for an objective assessment of the patterns of biogeochemical parameters in the White Sea. Rivers are the main contributors of pollutants from the watershed to the White Sea. The studies of the mouths flowing into the Onezhskiy Bay of the White Sea were carried out from June 20 to June 28, 2023. The distributions of hydrophysical, hydrochemical and biological parameters were obtained depending on the phase of the tidal cycle. The maximum of total phosphorus content was observed in the Nizhny Vyg River Mouth – 42 μg/l, the highest concentration of total nitrogen was in the Onega River Mouth – 0.37 mg N/l. In the mouth of the Kem’ River, concentration of ammonium nitrogen prevailed among inorganic forms, like directly in the river, which indicates anthropogenic impact. The highest values of chlorophyll-a were observed at the most desalinated station, in the Onega River the highest were detected – 2.20 mg/m3. The influence of the phases of the tidal cycle in the study area on the spatial and temporal variability of environmental characteristics was manifested in changes in temperature and salinity.