Glacial influence on the iron and sulfur cycles in Arctic fjord sediments (Svalbard)

Alexander B. Michaud; Katja Laufer; Alyssa Findlay; André Pellerin; Gilad Antler; Alexandra V. Turchyn; Hans Røy; Laura M. Wehrmann; Bo Barker Jørgensen

doi:10.1016/j.gca.2019.12.033

Glacial influence on the iron and sulfur cycles in Arctic fjord sediments (Svalbard)

Alexander B. Michaud^*, Katja Laufer, Alyssa Findlay, André Pellerin, Gilad Antler, Alexandra V. Turchyn, Hans Røy, Laura M. Wehrmann, Bo Barker Jørgensen

^*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avis › Tidsskriftartikel › Forskning › peer review

21 Citationer (Scopus)

Abstract

Arctic fjord sediments of Svalbard receive terrestrial material from glacial runoff and organic matter from marine primary productivity. Organic carbon mineralization proceeds primarily through sulfate and iron reduction in the fjord sediment. The ongoing retreat of glaciers in the high Arctic is altering the input of glacial material to the fjords, with unknown consequences for the iron and sulfur cycles in the fjord sediments. We measured sulfate reduction rates in sediment cores and analyzed porewater geochemistry, then compared these results to long-term sediment incubations to determine the rates of iron reduction and sulfide oxidation in three glacially influenced fjords on the west coast of Spitsbergen, Svalbard. Despite an abundance of glacially-sourced Fe(III)-oxide minerals, active sulfate reduction took place throughout the sediment. Analyses of the sulfur and oxygen isotopic composition of porewater sulfate and sulfate concentrations suggest that sulfide produced from biological sulfate reduction is reoxidized to sulfate. Long-term sediment incubations indicated sulfide oxidation at all three stations. The rate of sulfide oxidation was controlled by both the rate of sulfate reduction and the quantity and reactivity of Fe(III)-oxides. In our experimental incubations, we detected a decrease in Fe(III) content of the 0.5 M HCl and ascorbate-extractable fractions, but not in the 6 M HCl fraction, indicating that the highly reactive Fe(III) fraction is utilized by microorganisms and serves as the oxidant for sulfide oxidation. Our results show that sulfide oxidation in glacially-influenced fjord sediments is a wide-spread geochemical process. Further warming will drive glacial retreat onto land, where sediment-laden glacial meltwater will be altered during flow through proglacial streams and lakes before entering the marine environment. Fjord sediments will likely become more sulfidic, as glaciers deliver less particulate, highly-reactive metal oxides to the marine environment.

Originalsprog	Engelsk
Tidsskrift	Geochimica et Cosmochimica Acta
Vol/bind	280
Sider (fra-til)	423-440
Antal sider	18
ISSN	0016-7037
DOI	https://doi.org/10.1016/j.gca.2019.12.033
Status	Udgivet - 2020

Adgang til dokumentet

10.1016/j.gca.2019.12.033

Andre filer og links

http://www.scopus.com/inward/record.url?scp=85078849197&partnerID=8YFLogxK

Citationsformater

@article{fa47057e7ff34fd3b300be8e52c7cb42,

title = "Glacial influence on the iron and sulfur cycles in Arctic fjord sediments (Svalbard)",

abstract = "Arctic fjord sediments of Svalbard receive terrestrial material from glacial runoff and organic matter from marine primary productivity. Organic carbon mineralization proceeds primarily through sulfate and iron reduction in the fjord sediment. The ongoing retreat of glaciers in the high Arctic is altering the input of glacial material to the fjords, with unknown consequences for the iron and sulfur cycles in the fjord sediments. We measured sulfate reduction rates in sediment cores and analyzed porewater geochemistry, then compared these results to long-term sediment incubations to determine the rates of iron reduction and sulfide oxidation in three glacially influenced fjords on the west coast of Spitsbergen, Svalbard. Despite an abundance of glacially-sourced Fe(III)-oxide minerals, active sulfate reduction took place throughout the sediment. Analyses of the sulfur and oxygen isotopic composition of porewater sulfate and sulfate concentrations suggest that sulfide produced from biological sulfate reduction is reoxidized to sulfate. Long-term sediment incubations indicated sulfide oxidation at all three stations. The rate of sulfide oxidation was controlled by both the rate of sulfate reduction and the quantity and reactivity of Fe(III)-oxides. In our experimental incubations, we detected a decrease in Fe(III) content of the 0.5 M HCl and ascorbate-extractable fractions, but not in the 6 M HCl fraction, indicating that the highly reactive Fe(III) fraction is utilized by microorganisms and serves as the oxidant for sulfide oxidation. Our results show that sulfide oxidation in glacially-influenced fjord sediments is a wide-spread geochemical process. Further warming will drive glacial retreat onto land, where sediment-laden glacial meltwater will be altered during flow through proglacial streams and lakes before entering the marine environment. Fjord sediments will likely become more sulfidic, as glaciers deliver less particulate, highly-reactive metal oxides to the marine environment.",

keywords = "Arctic, Fjord, Glacier, Iron reactivity, Sulfate reduction, Sulfide oxidation, Svalbard",

author = "Michaud, {Alexander B.} and Katja Laufer and Alyssa Findlay and Andr{\'e} Pellerin and Gilad Antler and Turchyn, {Alexandra V.} and Hans R{\o}y and Wehrmann, {Laura M.} and J{\o}rgensen, {Bo Barker}",

year = "2020",

doi = "10.1016/j.gca.2019.12.033",

language = "English",

volume = "280",

pages = "423--440",

journal = "Geochimica et Cosmochimica Acta",

issn = "0016-7037",

publisher = "Pergamon Press",

}

TY - JOUR

T1 - Glacial influence on the iron and sulfur cycles in Arctic fjord sediments (Svalbard)

AU - Michaud, Alexander B.

AU - Laufer, Katja

AU - Findlay, Alyssa

AU - Pellerin, André

AU - Antler, Gilad

AU - Turchyn, Alexandra V.

AU - Røy, Hans

AU - Wehrmann, Laura M.

AU - Jørgensen, Bo Barker

PY - 2020

Y1 - 2020

N2 - Arctic fjord sediments of Svalbard receive terrestrial material from glacial runoff and organic matter from marine primary productivity. Organic carbon mineralization proceeds primarily through sulfate and iron reduction in the fjord sediment. The ongoing retreat of glaciers in the high Arctic is altering the input of glacial material to the fjords, with unknown consequences for the iron and sulfur cycles in the fjord sediments. We measured sulfate reduction rates in sediment cores and analyzed porewater geochemistry, then compared these results to long-term sediment incubations to determine the rates of iron reduction and sulfide oxidation in three glacially influenced fjords on the west coast of Spitsbergen, Svalbard. Despite an abundance of glacially-sourced Fe(III)-oxide minerals, active sulfate reduction took place throughout the sediment. Analyses of the sulfur and oxygen isotopic composition of porewater sulfate and sulfate concentrations suggest that sulfide produced from biological sulfate reduction is reoxidized to sulfate. Long-term sediment incubations indicated sulfide oxidation at all three stations. The rate of sulfide oxidation was controlled by both the rate of sulfate reduction and the quantity and reactivity of Fe(III)-oxides. In our experimental incubations, we detected a decrease in Fe(III) content of the 0.5 M HCl and ascorbate-extractable fractions, but not in the 6 M HCl fraction, indicating that the highly reactive Fe(III) fraction is utilized by microorganisms and serves as the oxidant for sulfide oxidation. Our results show that sulfide oxidation in glacially-influenced fjord sediments is a wide-spread geochemical process. Further warming will drive glacial retreat onto land, where sediment-laden glacial meltwater will be altered during flow through proglacial streams and lakes before entering the marine environment. Fjord sediments will likely become more sulfidic, as glaciers deliver less particulate, highly-reactive metal oxides to the marine environment.

AB - Arctic fjord sediments of Svalbard receive terrestrial material from glacial runoff and organic matter from marine primary productivity. Organic carbon mineralization proceeds primarily through sulfate and iron reduction in the fjord sediment. The ongoing retreat of glaciers in the high Arctic is altering the input of glacial material to the fjords, with unknown consequences for the iron and sulfur cycles in the fjord sediments. We measured sulfate reduction rates in sediment cores and analyzed porewater geochemistry, then compared these results to long-term sediment incubations to determine the rates of iron reduction and sulfide oxidation in three glacially influenced fjords on the west coast of Spitsbergen, Svalbard. Despite an abundance of glacially-sourced Fe(III)-oxide minerals, active sulfate reduction took place throughout the sediment. Analyses of the sulfur and oxygen isotopic composition of porewater sulfate and sulfate concentrations suggest that sulfide produced from biological sulfate reduction is reoxidized to sulfate. Long-term sediment incubations indicated sulfide oxidation at all three stations. The rate of sulfide oxidation was controlled by both the rate of sulfate reduction and the quantity and reactivity of Fe(III)-oxides. In our experimental incubations, we detected a decrease in Fe(III) content of the 0.5 M HCl and ascorbate-extractable fractions, but not in the 6 M HCl fraction, indicating that the highly reactive Fe(III) fraction is utilized by microorganisms and serves as the oxidant for sulfide oxidation. Our results show that sulfide oxidation in glacially-influenced fjord sediments is a wide-spread geochemical process. Further warming will drive glacial retreat onto land, where sediment-laden glacial meltwater will be altered during flow through proglacial streams and lakes before entering the marine environment. Fjord sediments will likely become more sulfidic, as glaciers deliver less particulate, highly-reactive metal oxides to the marine environment.

KW - Arctic

KW - Fjord

KW - Glacier

KW - Iron reactivity

KW - Sulfate reduction

KW - Sulfide oxidation

KW - Svalbard

UR - http://www.scopus.com/inward/record.url?scp=85078849197&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2019.12.033

DO - 10.1016/j.gca.2019.12.033

M3 - Journal article

AN - SCOPUS:85078849197

SN - 0016-7037

VL - 280

SP - 423

EP - 440

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -

Glacial influence on the iron and sulfur cycles in Arctic fjord sediments (Svalbard)

Abstract

Adgang til dokumentet

Andre filer og links

Fingeraftryk

Citationsformater