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Pupose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to represent a comprehensive study of the submarine groundwater discharge focus at the Cape Ayia using the hydrological, hydrochemical and radiochemical methods, as well as to determine the flux of submarine groundwater including the nutrients. Methods and Results. The scientific investigations were carried out during the coastal expeditions nearby the Cape Ayia on March 24, 2019, and also on April 22–24, 2019 during the 106th cruise of the R/V “Professor Vodyanitsky” (April 18–May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) in 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2%), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7%) with the energy 911.6 keV. The basic elements of the main biogenic cycle were determined using the photo-colorimetric means: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photo-colorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known focuses of the groundwater submarine discharge was studied. For the first time, the distribution of the 226Ra, 228Ra isotopes was studied. The data on salinity, volumetric activity of the 226Ra, 228Ra isotopes and the nutrients concentration permitted to determine the flows of submarine underground waters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.

Purpose. The study of submarine groundwater discharge is one of the most pressing issues of modern hydrogeology and oceanography. The purpose of the paper is to provide a comprehensive study of the submarine groundwater discharge at Cape Ayia using the hydrological, hydrochemical and radiochemical methods, and to determine the flux of submarine groundwater including the nutrients. Methods and Results. The research werecarried out during the coastal expeditions nearby Cape Ayia on March 24, 2019, and on April 22–24, 2019 during the 106th RV “Professor Vodyanitsky” cruise (April 18 – May 13, 2019). The isotopes 226Ra, 228Ra were extracted using the proprietary MnO2-based fibers. After concentration, the sorbent was squeezed to remove excess water, dried and ashed. Then the ash was placed in the Petri dishes and poured with epoxy resin. Activity of the radionuclides was measured on a low-background semiconductor γ-spectrometer with a detector of high-purity germanium (GC3020) 3 weeks after the resin casting. The activity of 226Ra was determined by the daughter radionuclide 214Pb with the energy 351.9 keV (qγ = 37.2 %), and that of 228Ra – by the daughter 228Ac (T1/2 = 6.1 h, qγ = 27.7 %) with the energy 911.6 keV. The basic elements of the main nutrient cycle were determined photocolorimetrically: mineral phosphorus – by molybdenum blue, silicon – by silicon-molybdenum complex. Nitrates (reduced to nitrites) and nitrites were determined by azo dye; ammonium – by indophenol blue also by the photocolorimetric method. Conclusions. Distribution of hydrophysical, hydrochemical and radiochemical parameters in the water area connected with the known submarine groundwater discharges was studied. The distribution of the 226Ra, 228Ra isotopes was studied for the first time. The data on salinity, specific activity of 226Ra, 228Ra and the nutrients concentration permitted to determine the flows of submarine groundwaters in the Cape Ayia area, which amounted to 8220 ± 1200 m3/day. The anthropogenic contribution to pollution of the groundwater forming the submarine sources is shown.

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Purpose. The aim of the work is to study spatial variability of the 137Cs and 40K concentrations in the bottom sediments of the Balaklava Bay, and to estimate the sedimentation rate and relative content of the biogenic fraction. Methods and Results. The results of the 137Cs and 40K concentration measurements in 5 columns of the bottom sediments sampled in various parts of the Balaklava Bay are represented. Activity of 137Cs and 40K in the samples was determined by the gamma spectrometric analysis. Based on the measurement data, spatial variability of the 137Cs and 40K concentration fields in the bottom sediments was studied, and the sedimentation rate was quantitatively estimated. Application of the balance equation provided quantitative estimates of the relative biogenic fraction content; its spatial variability was described. Quantitative estimates of the relationship between the biogenic fraction estimates resulted from use of the direct and indirect methods are represented. Conclusions. According to the obtained results, the 137Cs and 40K concentrations in the upper 5 cm layer of bottom sediments varied in space from 11 to 62 and from 155 to 562 Bq/kg, respectively. The maximum radionuclide concentrations were characteristic of the northern part of the bay, the minimum ones – of its southern part. The sedimentation average rate was 0.51 ± 0.06 cm/year. Relative biogenic fraction content in the sediments varied in space from 30 to 89% and averaged 46 ± 25%. The maximum values were observed in the southern part of the bay, the minimum ones – in the northern part.