Relationships between sulphur, organic carbon, and iron in the modern sediments of the Black Sea

Abstract. Compound-specific 13C and 14C compositions of diverse lipid biomarkers (fatty acids, alkenones, hydrocarbons, sterols and fatty alcohols) were measured in sinking particulate matter collected in sediment traps and from underlying surface sediments in the Black Sea, the Arabian Sea and the Ross Sea. The goal was to develop a multiparameter approach to constrain relative inputs of organic carbon (OC) from marine biomass, terrigenous vascular-plant and relict-kerogen sources. Using an isotope mass balance, we calculate that marine biomass in sediment trap material from the Black Sea and Arabian Sea accounted for 66–100% of OC, with lower terrigenous (3–8%) and relict (4–16%) contributions. Marine biomass in sediments constituted lower proportions of OC (66–90%), with consequentially higher proportions of terrigenous and relict carbon (3–17 and 7–13%, respectively). Ross Sea data were insufficient to allow similar mass balance calculations. These results suggest that, whereas particulate organic carbon is overwhelmingly marine in origin, pre-aged allochthonous terrigenous and relict OC become proportionally more important in sediments, consistent with pre-aged OC being better preserved during vertical transport to and burial at the seafloor than the upper-ocean-derived marine OC.

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Sulfur, iron and organic carbon fluxes in the Black Sea: sulfur isotopic evidence for origin of sulfur fluxes

Deep Sea Research Part A Oceanographic Research Papers ◽

10.1016/s0198-0149(10)80029-9 ◽

1991 ◽

Vol 38 ◽

pp. S1151-S1187 ◽

Cited By ~ 94

Author(s):

Jo Ann Muramoto ◽

Susumu Honjo ◽

Brian Fry ◽

Bernward J. Hay ◽

Robert W. Howarth ◽

...

Keyword(s):

Organic Carbon ◽

Black Sea ◽

Carbon Fluxes ◽

The Black Sea ◽

Isotopic Evidence ◽

Organic Carbon Fluxes

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The oceanic budgets of nickel and zinc isotopes: the importance of sulfidic environments as illustrated by the Black Sea

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2015.0294 ◽

2016 ◽

Vol 374 (2081) ◽

pp. 20150294 ◽

Cited By ~ 37

Author(s):

Derek Vance ◽

Susan H. Little ◽

Corey Archer ◽

Vyllinniskii Cameron ◽

Morten B. Andersen ◽

...

Keyword(s):

Organic Carbon ◽

Water Column ◽

Black Sea ◽

The Black Sea ◽

Zinc Isotopes ◽

Trace Element Chemistry ◽

Dissolved Species ◽

Climatic Impacts ◽

Sulfide Species ◽

Equilibrium Fractionation

Isotopic data collected to date as part of the GEOTRACES and other programmes show that the oceanic dissolved pool is isotopically heavy relative to the inputs for zinc (Zn) and nickel (Ni). All Zn sinks measured until recently, and the only output yet measured for Ni, are isotopically heavier than the dissolved pool. This would require either a non-steady-state ocean or other unidentified sinks. Recently, isotopically light Zn has been measured in organic carbon-rich sediments from productive upwelling margins, providing a potential resolution of this issue, at least for Zn. However, the origin of the isotopically light sedimentary Zn signal is uncertain. Cellular uptake of isotopically light Zn followed by transfer to sediment does not appear to be a quantitatively important process. Here, we present Zn and Ni isotope data for the water column and sediments of the Black Sea. These data demonstrate that isotopically light Zn and Ni are extracted from the water column, probably through an equilibrium fractionation between different dissolved species followed by sequestration of light Zn and Ni in sulfide species to particulates and the sediment. We suggest that a similar, non-quantitative, process, operating in porewaters, explains the Zn data from organic carbon-rich sediments. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.

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