Abstract
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.
Highlights
The dynamics of sources, sinks and processes that control the burial of organic carbon (OC) in marine sediments have important implications for the global carbon cycle, paleoceanographic reconstructions and understanding climate variability (Berner, 1982; Hedges and Keil, 1995; Burdige, 2007; Zonneveld et al, 2010)
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
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
Summary
The dynamics of sources, sinks and processes that control the burial of organic carbon (OC) in marine sediments have important implications for the global carbon cycle, paleoceanographic reconstructions and understanding climate variability (Berner, 1982; Hedges and Keil, 1995; Burdige, 2007; Zonneveld et al, 2010). Even at open-ocean locations remote from the continents where marine OC dominates the water column flux via the biological pump, a terrigenous component delivered by long-range aeolian transport (Zafiriou et al, 1995; Gagosian and Peltzer, 1986; Eglinton et al, 2002; Kawamura et al, 2003) is still recognizable in sediments (Prahl et al, 1989; Wakeham et al, 2002; Zonneveld et al, 2010). Even a small fraction of the most recalcitrant relict carbon is amenable to bacterial assimilation
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