Biogenic sedimentation in the Black Sea: radiotracer-derived study
Method for differentiated assessment of the rate of biogenic and lithogenic sedimentation in the Black Sea using the naturally occurring radionuclide potassium-40 has been developed. This allows evaluation the contribution of biosedimentation to the total process of the sediment accumulation within the entire range of the Black Sea depths. Based upon this method, it was shown that near the estuarine zones of rivers entering the north-western Black Sea, down to 20 m of a water depth, the allochthonous material prevails in the seabed sediments, whereas deeper than the shelf edge (> 120 m) the sediments consist almost completely of autochthonous suspended matter. The studies performed in Sevastopol Bay have showed that sediment accumulation rate is positively correlated with the percentage of biogenic matter in the upper sediment layer. This suggests the significance of biotic processes in transfer of suspended matter, as well as in the forming and accumulation of sediments in Sevastopol Bay. The obtained data, in combination with study of bioproduction processes in the Black Sea water column, may be applied for purposes related to evaluation of the capability of marine environments for self-purification and de-eutrophication governed by sedimentation.