Distribution of beryllium-7 (7Be) in the Black Sea in the summer of 2016.

The spatial distribution of 7Be activity in the surface layer of the Black Sea was studied using the data of field observations made during the 87th cruise of R/V Professor Vodyanitskii. Activity of 7Be varied spatially from 4.6 to 9.5 Bq m-3 (mean 7.5 ± 1.3 Bq m-3) where about 9% was found on suspended matter. The minimum values of activity were typical for samples taken in the shelf waters and the maximum-offshore. The influence of different factors on 7Be activity was analyzed. It was revealed that variation of both 7Be wet deposition on the sea surface and concentration of suspended matter were the most significant for spatiotemporal variability of 7Be activity in seawater during the study period. The estimates of 7Be distribution coefficient between dissolved and particulate forms were obtained. This coefficient varied from 1.5·105 to 2.4·105 L kg-1, averaged (1.9 ± 0.3)·105 L kg-1.