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Understanding the Dynamics of the Oxic‐Anoxic Interface in the Black Sea
Author(s) -
Stanev Emil V.,
Poulain PierreMarie,
Grayek Sebastian,
Johnson Kenneth S.,
Claustre Hervé,
Murray James W.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl076206
Subject(s) - anoxic waters , biogeochemical cycle , geology , oceanography , earth science , environmental chemistry , chemistry
The Black Sea, the largest semienclosed anoxic basin on Earth, can be considered as an excellent natural laboratory for oxic and anoxic biogeochemical processes. The suboxic zone, a thin interface between oxic and anoxic waters, still remains poorly understood because it has been undersampled. This has led to alternative concepts regarding the underlying processes that create it. Existing hypotheses suggest that the interface originates either by isopycnal intrusions that introduce oxygen or the dynamics of manganese redox cycling that are associated with the sinking of particles or chemosynthetic bacteria. Here we reexamine these concepts using high‐resolution oxygen, sulfide, nitrate, and particle concentration profiles obtained with sensors deployed on profiling floats. Our results show an extremely stable structure in density space over the entire basin with the exception of areas near the Bosporus plume and in the southern areas dominated by coastal anticyclones. The absence of large‐scale horizontal intrusive signatures in the open‐sea supports a hypothesis prioritizing the role of biogeochemical processes.