ASSESSMENT OF SEDIMENTATION RATE IN THE BALAKLAVA BAY BY RADIONUCLIDES.

The study of regional characteristics of the bottom sediments physicochemical structure in semi-closed water areas (using the example of the Balaklava Bay) is especially relevant due to the fact that the recreational potential development rate of this region has significantly increased. During the studies, 3 columns (two in northern part of the bay and one in southern) of bottom sediments were taken and the activity of ¹³⁷Cs, ²¹⁰Pb, and 226Ra in them was determined. Column samples were taken using an acrylic soil tube with an inner diameter of 60 mm and a vacuum shutter. According to the lithological description, the columns selected in the northern basin are similar. The upper layer 0 – 1 cm is represented by a light brown liquid silt with inclusions of plant debris and shell, layer 1 – 11 cm is represented by light gray, gray silt with the inclusion of broken shell and sand, layer 11 – 19 is represented by dense dark gray and black silt without inclusions. For the column, selected in the southern part of the bay, an increased content of sand material, individual shells and shell detritus was noted. Measurements of the activity of ¹³⁷Cs, ²¹⁰Pb, and ²¹⁴Bi in samples of bottom sediments were carried out on a low-background gamma spectrometer with a well-type NaI (Tl) scintillation detector. The spatial distribution of radionuclides was similar: the maximum concentration values were noted in the northern part of the bay, the minimum – in the southern part. Quantitative estimates of the sedimentation rate were obtained based on the data on the vertical distribution of the activity of these radionuclides. Spatiotemporal variability of sedimentation rate was studied. It was found that according to ¹³⁷Cs data the sedimentation rate varies spatially from 0.12 to 0.59 cm/yr and according to ²¹⁰Pb data – from 0.74 to 0.91 cm/yr. [ABSTRACT FROM AUTHOR]