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Title: COASTAL HYPOXIA IN AREAS UNDER ANTHROPOGENIC PRESSURE
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COASTAL HYPOXIA IN AREAS UNDER ANTHROPOGENIC PRESSURE
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1314-2704
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English
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20
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3.1
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An increase of anthropogenic load and intake of organic matter and nutrients leads to extremely negative consequences for coastal marine ecosystems. This is due to the fact that organic matter, deposited in the bottom sediments, contributes to the consumption of oxygen for its oxidation. With a lack of oxygen on the processes of mineralization of organic matter, its accumulation occurs. Oxygen consumption and organic matter accumulation in bottom sediments lead to appearance of anaerobic conditions in sediments and bottom waters. Oxygen deficiency (hypoxia) zones are formed, that defines ecological characteristics and biodiversity of marine ecosystems. Coastal areas of the Crimean shelf and bays of the Sevastopol region (Balaklava, Kruglaya, Kazach?ya and Sevastopol Bays), which have high recreational, social and economic importance, are considered in this work. The data obtained in September 2018 and July 2019 was analyzed. Samples were taken with plexiglass tubes hermetically sealed above and below. To obtain key redox species profiles of pore water, a voltammetry analysis with a glass Au-Hg microelectrode was used. The oxygen fluxes were calculated at bottom water-sediment boundary. Based on the obtained data, the main biogeochemical processes in the bottom waters and sediments of considered areas were studied; a forecast of oxygen deficiency and anaerobic conditions appearance in the bottom waters was given. In the bays of the Sevastopol region, oxygen deficiency is affected by anthropogenic activity, as well as restricted water dynamics. In the open coastal regions of the Black Sea, with the exception of areas suffer from severe anthropogenic pressure (Yalta, Feodosia Gulf, Karkinitsky Gulf), water dynamics contribute to the saturation of the bottom waters with oxygen The value of oxygen flux and it in bottom water?s concentration were used to calculate the time of development of oxygen deficiency. It was stated periods changed from 5 years in open areas, up to 1 month in regions with restricted water exchange. It was found, that hypoxia is observed at the surface of bottom sediments of the Western part of the Crimean coast, Feodosia Gulf and the coastal part of Crimea in the Sea of Azov. In areas with aerobic conditions, the main factor determined redox conditions is water dynamics. It effects on the oxygen saturation of the bottom waters. However, in case of changing conditions and limiting water exchange in these areas, oxygen deficiency zones may also appear.
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conference
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20th International Multidisciplinary Scientific GeoConference SGEM 2020
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20th International Multidisciplinary Scientific GeoConference SGEM 2020, 18 - 24 August, 2020
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Proceedings Paper
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STEF92 Technology
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International Multidisciplinary Scientific GeoConference-SGEM
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SWS Scholarly Society; Acad Sci Czech Republ; Latvian Acad Sci; Polish Acad Sci; Russian Acad Sci; Serbian Acad Sci & Arts; Natl Acad Sci Ukraine; Natl Acad Sci Armenia; Sci Council Japan; European Acad Sci, Arts & Letters; Acad Fine Arts Zagreb Croatia; C
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823-830
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18 - 24 August, 2020
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website
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cdrom
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7201
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bottom sediments; pore waters; organic carbon; grain-size of sediments; voltammetry; oxygen; hydrogen sulfide; Black Sea.
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