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

Johan C Faust, Allyson Tessin, Ben J Fisher, Mark Zindorf, Sonia Papadaki, Katharine R Hendry, Katherine A Doyle, Christian März

Research output: Contribution to journalArticle (Academic Journal)peer-review

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.
Original languageEnglish
JournalNature Communications
Publication statusAccepted/In press - 3 Dec 2020

Keywords

  • Barents Sea
  • geochemical sediment composition
  • carbon cycle
  • Arctic Ocean
  • pore water chemistry
  • reactive iron and manganese
  • redox boundary

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