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Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea

The Black Sea is the largest euxinic basin on the Earth. The anoxic zone consists of the upper part water mass stratified by density, and the lower water mass homogenized relative to density (depth >1750 m), named the Bottom Convective Layer. To assess homogeneity and possible exchange of matter...

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Autores principales: Dubinin, Alexander V, Dubinina, Elena O, Demidova, Tatyana P, Kokryatskaya, Nataliya M, Rimskaya-Korsakova, Maria N, Kosova, Sofia A, Yakushev, Evgeniy V
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3997503/
https://www.ncbi.nlm.nih.gov/pubmed/24739078
http://dx.doi.org/10.1186/1467-4866-15-3
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author Dubinin, Alexander V
Dubinina, Elena O
Demidova, Tatyana P
Kokryatskaya, Nataliya M
Rimskaya-Korsakova, Maria N
Kosova, Sofia A
Yakushev, Evgeniy V
author_facet Dubinin, Alexander V
Dubinina, Elena O
Demidova, Tatyana P
Kokryatskaya, Nataliya M
Rimskaya-Korsakova, Maria N
Kosova, Sofia A
Yakushev, Evgeniy V
author_sort Dubinin, Alexander V
collection PubMed
description The Black Sea is the largest euxinic basin on the Earth. The anoxic zone consists of the upper part water mass stratified by density, and the lower water mass homogenized relative to density (depth >1750 m), named the Bottom Convective Layer. To assess homogeneity and possible exchange of matter across the upper and lower boundaries of the Bottom Convective Layer, new data on stable isotope composition of S, O and H were obtained. Samples were collected in August 2008 and March 2009 from two stations located in the eastern central part of the Black Sea. Distribution of δ(18)O and δD values of water for the entire water column did not vary seasonally. Appreciable differences were marked for δD value variation in the picnocline area (water depth 200-400 m) and in the BCL 5 m above the bottom that might be caused by penetration of intrusions with elevated portion of shelf modified Mediterranean Water. Observed linear relationship between δ(18)O (or δD) and salinity indicates that mixing water and salt occurs at the same time, and the deep water of the Black Sea has two end members: the high-salinity Mediterranean seawater and freshwater input. In the Bottom Convective Layer, the average δ(34)S (H(2)S) was -40.6 ± 0.5‰ and did not vary seasonally. At the bottom (depth > 2000 m), (34)S depletion down to –41.0‰ was observed. Our δ(34)S (SO(4)) data are by 2-3‰ higher than those measured previously for the Bottom Convective Layer. Sulfate from the aerobic zone with δ(34)S (SO(4)) = +21‰ corresponds to ocean water sulfate and that has not been subjected to sulfate reduction. Average δ(34)S (SO(4)) values for depths > 1250 m were found to be +23.0 ± 0.2‰ (1σ). Sulfur isotope composition of sulfate does not change in the Bottom Convective Layer and on its upper and lower boundaries, and does not depend on the season of observation.
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spelling pubmed-39975032014-04-30 Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea Dubinin, Alexander V Dubinina, Elena O Demidova, Tatyana P Kokryatskaya, Nataliya M Rimskaya-Korsakova, Maria N Kosova, Sofia A Yakushev, Evgeniy V Geochem Trans Research Article The Black Sea is the largest euxinic basin on the Earth. The anoxic zone consists of the upper part water mass stratified by density, and the lower water mass homogenized relative to density (depth >1750 m), named the Bottom Convective Layer. To assess homogeneity and possible exchange of matter across the upper and lower boundaries of the Bottom Convective Layer, new data on stable isotope composition of S, O and H were obtained. Samples were collected in August 2008 and March 2009 from two stations located in the eastern central part of the Black Sea. Distribution of δ(18)O and δD values of water for the entire water column did not vary seasonally. Appreciable differences were marked for δD value variation in the picnocline area (water depth 200-400 m) and in the BCL 5 m above the bottom that might be caused by penetration of intrusions with elevated portion of shelf modified Mediterranean Water. Observed linear relationship between δ(18)O (or δD) and salinity indicates that mixing water and salt occurs at the same time, and the deep water of the Black Sea has two end members: the high-salinity Mediterranean seawater and freshwater input. In the Bottom Convective Layer, the average δ(34)S (H(2)S) was -40.6 ± 0.5‰ and did not vary seasonally. At the bottom (depth > 2000 m), (34)S depletion down to –41.0‰ was observed. Our δ(34)S (SO(4)) data are by 2-3‰ higher than those measured previously for the Bottom Convective Layer. Sulfate from the aerobic zone with δ(34)S (SO(4)) = +21‰ corresponds to ocean water sulfate and that has not been subjected to sulfate reduction. Average δ(34)S (SO(4)) values for depths > 1250 m were found to be +23.0 ± 0.2‰ (1σ). Sulfur isotope composition of sulfate does not change in the Bottom Convective Layer and on its upper and lower boundaries, and does not depend on the season of observation. BioMed Central 2014-04-17 /pmc/articles/PMC3997503/ /pubmed/24739078 http://dx.doi.org/10.1186/1467-4866-15-3 Text en Copyright © 2014 Dubinin et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.
spellingShingle Research Article
Dubinin, Alexander V
Dubinina, Elena O
Demidova, Tatyana P
Kokryatskaya, Nataliya M
Rimskaya-Korsakova, Maria N
Kosova, Sofia A
Yakushev, Evgeniy V
Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title_full Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title_fullStr Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title_full_unstemmed Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title_short Stable isotope evidence for the Bottom Convective Layer homogeneity in the Black Sea
title_sort stable isotope evidence for the bottom convective layer homogeneity in the black sea
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3997503/
https://www.ncbi.nlm.nih.gov/pubmed/24739078
http://dx.doi.org/10.1186/1467-4866-15-3
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