The Seasonal Dynamics of Biosedimentation and Primary Production in Sevastopol Bay: Assessment of the Relationship Using 234Th and 40K

Аннотация

The seasonal dynamics of biogenic sedimentation in Sevastopol Bay, Black Sea, was studied using thorium-234 (²³⁴Th) as a natural radiotracer. The percentage content of biogenic particulate matter in bottom sediments was determined based on the ⁴⁰K radionuclide according to the previously developed method. Two major maxima of the rate of bottom sedimentation have been recorded: in April–June and in the second half of the summer. In the former case, the peak can apparently be attributed to a more intensive flux of terrigenous particulate matter in the spring; in the latter case, it can apparently be attributed to high values of phytoplankton primary production in the late summer. The results obtained by applying this method provide a more accurate estimate of the mean annual biosedimentation rate, which is required to calculate deposition fluxes of biogenic matter and pollutants to bottom sediments of coastal waters.