Content of toxic substances in the deep-sea and coastal areas of the Black Sea off the Crimean Peninsula in spring — autumn, 2019

Based on the results of 4 surveys conducted in the Black Sea off the Crimean Peninsula in spring, summer and autumn, 2019, an assessment was made of the water and bottom sediments polluted with petroleum components, PAH, organochlorine pesticides, PCBs, heavy metals, arsenic and caesium-137. In the water column of the deep-seafregion and the western coast of the Crimean Peninsula, hydrocarbon concentrations ranged from <0.015 to 0.39 mg/l. Resins and asphaltenes were found in the surface waters of the eastern Crimea only in summer and autumn, and made up 7.3–40 % of the total oil components. The concentrations of petroleum products in the studied sediments varied from <0.02 to 0.96 g/kg of dry weight. The portion of resins and asphaltenes was in the range of 15–30 %. Total concentrations of individual PAHs in the studied waters varied from 7.04 to 96.01 ng/l, in bottom sediments they ranged from 33 to 366 mcg/kg of dry weight. Benzo(a)pyrene, an indicator for PAHs contamination, made up 0.3–3.4 % in water and 0.5–1.1 % in bottom sediments on the amount of total PAHs. No excess of MPC for naphthalene and benzo(a) pyrene was found in the water. MPC for organochlorine pesticides and PCBs set for the fishery waters (MPC f ) were also not exceeded. A single case of 2.2 times exceeded MPC f for iron was recorded in the deep-sea region off the cape Ayu- Dag. In all the seasons, in deep-sea of the Black Sea, an excess of MPC f for manganese was detected, which is not associated with anthropogenic pollution, but with the accumulation of manganese in the hydrosulfuric water layer. Higher concentrations of copper, lead, cadmium, zinc, nickel and arsenic were observed in bottom sediments of the deep-sea stretch between Sevastopol Bay and Cape Meganom. As to the bottom sediments of the shelf, the highest concentrations of chromium, mercury, iron and manganese were found in Feodosiysky Bay, Lake Donuzlav and off Cape Sarych