Millennial scale persistence of organic carbon bound to iron in Arctic marine sediments

• Published in: Nature Communications
• Main Authors: Faust, Johan C., Tessin, Allyson, Fisher, Ben J., Zindorf, Mark, Papadaki, Sonia, Hendry, Katharine R., Doyle, Katherine A., März, Christian
• Other Authors: RCUK | Natural Environment Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry; Arctic; Barents Sea
• Online Access: http://dx.doi.org/10.1038/s41467-020-20550-0; http://www.nature.com/articles/s41467-020-20550-0.pdf; http://www.nature.com/articles/s41467-020-20550-0

Abstract Burial of organic material in marine sediments represents a dominant natural mechanism of long-term carbon sequestration globally, but critical aspects of this carbon sink remain unresolved. Investigation of surface sediments led to the proposition that on average 10-20% of sedimentary organic carbon is stabilised and physically protected against microbial degradation through binding to reactive metal (e.g. iron and manganese) oxides. Here we examine the long-term efficiency of this rusty carbon sink by analysing the chemical composition of sediments and pore waters from four locations in the Barents Sea. Our findings show that the carbon-iron coupling persists below the uppermost, oxygenated sediment layer over thousands of years. We further propose that authigenic coprecipitation is not the dominant factor of the carbon-iron bounding in these Arctic shelf sediments and that a substantial fraction of the organic carbon is already bound to reactive iron prior deposition on the seafloor.