The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments
We explore the dynamics of the subsurface sulfur, iron and carbon cycles in salt marsh sediments from East Anglia, United Kingdom. We report measurements of pore fluid and sediment geochemistry, coupled with results from laboratory sediment incubation experiments, and develop a conceptual model to d...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-06-01
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| Series: | Frontiers in Earth Science |
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| Online Access: | https://www.frontiersin.org/article/10.3389/feart.2019.00140/full |
| _version_ | 1811201737684418560 |
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| author | Gilad Antler Gilad Antler Jennifer V. Mills Alec M. Hutchings Kelly R. Redeker Alexandra V. Turchyn |
| author_facet | Gilad Antler Gilad Antler Jennifer V. Mills Alec M. Hutchings Kelly R. Redeker Alexandra V. Turchyn |
| author_sort | Gilad Antler |
| collection | DOAJ |
| description | We explore the dynamics of the subsurface sulfur, iron and carbon cycles in salt marsh sediments from East Anglia, United Kingdom. We report measurements of pore fluid and sediment geochemistry, coupled with results from laboratory sediment incubation experiments, and develop a conceptual model to describe the influence of bioturbation on subsurface redox cycling. In the studied sediments the subsurface environment falls into two broadly defined geochemical patterns – iron-rich sediments or sulfide-rich sediments. Within each sediment type nearly identical pore fluid and solid phase geochemistry (in terms of concentrations of iron, sulfate, sulfide, dissolved inorganic carbon (DIC), and the sulfur and oxygen isotope compositions of sulfate) are observed in sediments that are hundreds of kilometers apart. Strictly iron-rich and strictly sulfide-rich sediments, despite their substantive geochemical differences, are observed within spatial distances of less than five meters. We suggest that this bistable system results from a series of feedback reactions that determine ultimately whether sediments will be sulfide-rich or iron-rich. We suggest that an oxidative cycle in the iron-rich sediment, driven by bioirrigation, allows rapid oxidation of organic matter, and that this irrigation impacts the sediment below the immediate physical depth of bioturbation. This oxidative cycle yields iron-rich sediments with low total organic carbon, dominated by microbial iron reduction and no methane production. In the absence of bioirrigation, sediments in the salt marsh become sulfide-rich with high methane concentrations. Our results suggest that the impact of bioirrigation not only drives recycling of sedimentary material but plays a key role in sedimentary interactions among iron, sulfur and carbon. |
| first_indexed | 2024-04-12T02:26:56Z |
| format | Article |
| id | doaj.art-b4239b6be93540f28a2533b2269fe9b4 |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-04-12T02:26:56Z |
| publishDate | 2019-06-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-b4239b6be93540f28a2533b2269fe9b42022-12-22T03:51:56ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632019-06-01710.3389/feart.2019.00140413326The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh SedimentsGilad Antler0Gilad Antler1Jennifer V. Mills2Alec M. Hutchings3Kelly R. Redeker4Alexandra V. Turchyn5Department of Geological and Environmental Sciences, Ben-Gurion University of the Negev, Beersheba, IsraelThe Interuniversity Institute for Marine Sciences, Eilat, IsraelDepartment of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United StatesDepartment of Earth Sciences, University of Cambridge, Cambridge, United KingdomDepartment of Biology, University of York, Heslington, United KingdomDepartment of Earth Sciences, University of Cambridge, Cambridge, United KingdomWe explore the dynamics of the subsurface sulfur, iron and carbon cycles in salt marsh sediments from East Anglia, United Kingdom. We report measurements of pore fluid and sediment geochemistry, coupled with results from laboratory sediment incubation experiments, and develop a conceptual model to describe the influence of bioturbation on subsurface redox cycling. In the studied sediments the subsurface environment falls into two broadly defined geochemical patterns – iron-rich sediments or sulfide-rich sediments. Within each sediment type nearly identical pore fluid and solid phase geochemistry (in terms of concentrations of iron, sulfate, sulfide, dissolved inorganic carbon (DIC), and the sulfur and oxygen isotope compositions of sulfate) are observed in sediments that are hundreds of kilometers apart. Strictly iron-rich and strictly sulfide-rich sediments, despite their substantive geochemical differences, are observed within spatial distances of less than five meters. We suggest that this bistable system results from a series of feedback reactions that determine ultimately whether sediments will be sulfide-rich or iron-rich. We suggest that an oxidative cycle in the iron-rich sediment, driven by bioirrigation, allows rapid oxidation of organic matter, and that this irrigation impacts the sediment below the immediate physical depth of bioturbation. This oxidative cycle yields iron-rich sediments with low total organic carbon, dominated by microbial iron reduction and no methane production. In the absence of bioirrigation, sediments in the salt marsh become sulfide-rich with high methane concentrations. Our results suggest that the impact of bioirrigation not only drives recycling of sedimentary material but plays a key role in sedimentary interactions among iron, sulfur and carbon.https://www.frontiersin.org/article/10.3389/feart.2019.00140/fullbioturbationsulfurironcarbonsalt marshisotopes |
| spellingShingle | Gilad Antler Gilad Antler Jennifer V. Mills Alec M. Hutchings Kelly R. Redeker Alexandra V. Turchyn The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments Frontiers in Earth Science bioturbation sulfur iron carbon salt marsh isotopes |
| title | The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments |
| title_full | The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments |
| title_fullStr | The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments |
| title_full_unstemmed | The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments |
| title_short | The Sedimentary Carbon-Sulfur-Iron Interplay – A Lesson From East Anglian Salt Marsh Sediments |
| title_sort | sedimentary carbon sulfur iron interplay a lesson from east anglian salt marsh sediments |
| topic | bioturbation sulfur iron carbon salt marsh isotopes |
| url | https://www.frontiersin.org/article/10.3389/feart.2019.00140/full |
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