Dynamics of Background Radiation in Russian Seas (New Data on the Sea of Azov)
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NOLOGY
Dynamics of Background Radiation in Russian Seas (New Data on the Sea of Azov) Academician G. G. Matishova,b,*, V. V. Polshina, G. V. Ilyinb, and I. S. Usyaginab Received April 28, 2020; revised May 7, 2020; accepted May 25, 2020
Abstract—New data on the concentration of 137Cs in the water and bottom sediments of the Sea of Azov are analyzed. The factors determining the entry and redistribution of technogenic radionuclides in the seas are discussed. The increased background of radioactivity in the Sea of Azov is supported by the recirculation of radionuclides transported after the accident at the Chernobyl nuclear power station. Keywords: radioactivity, marine environment, bottom sediments DOI: 10.1134/S1028334X20080127
INTRODUCTION Due to the river system, more technogenic radioisotopes accumulate in the bottom sediments of the Sea of Azov than in the sediments of other seas [1–3]. The need for a comparative analysis of the radiation state of the arctic and arid seas is obvious. Since 1997, the Murmansk Marine Biological Institute and the Southern Science Center of the Russian Academy of Sciences have been conducting joint ecosystem monitoring. In this paper, we analyze new material on marine suspension and bottom sediments of the Sea of Azov (Figs. 1, 2; Table 1). MATERIALS AND METHODS New data on the pollution of bottom sediments, the concentration of suspended matter, and 137Cs in the marine environment were collected during the expedition on the vessel Deneb in July 2019. Bottom sediments (0–3 cm layer) were taken using a Van Veen grab and a core sampler at depths from 5 to 13 m (Figs. 1, 2; Table 1). The radioactivity of cesium radioisotopes in the water samples was determined by the concentration method on the cellulose inorganic sorbent “Anfezh” (sample volume is 100 l). The radioactivity of 137Cs in the samples of the sorbent and bottom sediments was measured using InSpector-2000 gamma-ray spectrometers (CanberraIndustries, Inc., United States). The spectra were analyzed using a Federal
Research Center, Southern Science Center, Russian Academy of Sciences, Rostov-on-Don, 344006 Russia b Murmansk Marine Biological Institute, Kola Science Center, Russian Academy of Sciences, Murmansk, 183010 Russia *e-mail: [email protected]
Genie-2000 software. The specific activity of 137Cs in the bottom sediments is given per unit dry mass of the sample. RESULTS AND DISCUSSION The specificity of sedimentation is that terrigenous and anthropogenic material settles on the inland continental shelf of the Sea of Azov. The suspension flow is directed towards the Panov marine accumulative plain. In July 2019, the maximum concentration of suspended matter in the surface and bottom layers of the water was recorded in the eastern part of Taganrog Bay (Fig. 1). A variation in the turbidity from the Don seashore to the ridge of Peschany Island (from 53.1/48.1 mg/l to 2.8/21.4 mg/l) was noted (at the surface and at the bottom), while the volumetric activity of 137Cs was low (1–4 Bq/m3) (Table 1, Fig. 1). The turbi
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