Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling

A case study from Mangrove Lake, Bermuda

André Pellerin, Thi Hao Bui, Mikaella Rough, Alfonso Mucci, Donald Eugene Canfield, Boswell A. Wing

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

The multiple sulfur isotope composition of porewater sulfate from the anoxic marine sapropel of Mangrove Lake, Bermuda was measured in order to establish how multiple sulfur isotopes are fractionated during reoxidative sulfur cycling.
The porewater-sulfate d34S and D33S dataset exhibits the distinct isotopic signatures of microbial sulfate reduction and sulfur reoxidation. We reproduced the measurements with a simple diagenetic model that yielded fractionation factors for net sulfate removal of between 29.2 0/00 and 32.5 0/00. A new approach to isotopic modeling of the sulfate profiles, informed by the chemistry of sulfur intermediate compounds in Mangrove Lake, reveals that sulfate reduction produces a relatively small intrinsic fractionation and that an active reoxidative sulfur cycle increases the fractionation of the measured values. Based on the model results, the reoxidative cycle of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80% of the sulfide produced by microbial sulfate reduction. The Mangrove Lake case study shows how sulfur isotope fractionations can be separated into three different “domains” in D33S–d34S space based on their ability to resolve reductive and reoxidative sulfur transformations. The first domain that differentiates reductive and reoxidative sulfur cycling is well illustrated by previous studies and requires 34S–32S fractionations more negative than 70&, beyond the fractionation limit of microbial sulfate reduction at earth surface temperatures. The second domain that
distinguishes reductive and reoxidative processes is between 34S–32S fractionations of 40&and 0&, where the 33S–32S fractionations of sulfate reduction and reoxidation are significantly different. In the remaining domain (between 34S–32S fractionations 70& and 40&), the similarity of the multiple sulfur isotope signals from microbial sulfate reduction and disproportionation means that the two processes cannot be discriminated from each other.
OriginalsprogEngelsk
TidsskriftGeochimica et Cosmochimica Acta
Vol/bind149
Sider (fra-til)152-164
ISSN0016-7037
DOI
StatusUdgivet - jan. 2015

Fingeraftryk

sulfur isotope
mangrove
fractionation
sulfur
sulfate
lake
sulfur cycle
sulfide
porewater
sapropel
turnover
surface temperature
oxidation

Citer dette

Pellerin, André ; Bui, Thi Hao ; Rough, Mikaella ; Mucci, Alfonso ; Canfield, Donald Eugene ; Wing, Boswell A. / Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling : A case study from Mangrove Lake, Bermuda. I: Geochimica et Cosmochimica Acta. 2015 ; Bind 149. s. 152-164.
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title = "Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling: A case study from Mangrove Lake, Bermuda",
abstract = "The multiple sulfur isotope composition of porewater sulfate from the anoxic marine sapropel of Mangrove Lake, Bermuda was measured in order to establish how multiple sulfur isotopes are fractionated during reoxidative sulfur cycling. The porewater-sulfate δ34S and Δ33S dataset exhibits the distinct isotopic signatures of microbial sulfate reduction and sulfur reoxidation. We reproduced the measurements with a simple diagenetic model that yielded fractionation factors for net sulfate removal of between −29.2‰ and −32.5‰. A new approach to isotopic modeling of the sulfate profiles, informed by the chemistry of sulfur intermediate compounds in Mangrove Lake, reveals that sulfate reduction produces a relatively small intrinsic fractionation and that an active reoxidative sulfur cycle increases the fractionation of the measured values. Based on the model results, the reoxidative cycle of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80{\%} of the sulfide produced by microbial sulfate reduction. The Mangrove Lake case study shows how sulfur isotope fractionations can be separated into three different “domains” in Δ33S–δ34S space based on their ability to resolve reductive and reoxidative sulfur transformations. The first domain that differentiates reductive and reoxidative sulfur cycling is well illustrated by previous studies and requires 34S–32S fractionations more negative than ≈−70‰, beyond the fractionation limit of microbial sulfate reduction at earth surface temperatures. The second domain that distinguishes reductive and reoxidative processes is between 34S–32S fractionations of −40‰ and 0‰, where the 33S–32S fractionations of sulfate reduction and reoxidation are significantly different. In the remaining domain (between 34S–32S fractionations −70‰ and −40‰), the similarity of the multiple sulfur isotope signals from microbial sulfate reduction and disproportionation means that the two processes cannot be discriminated from each other.",
author = "Andr{\'e} Pellerin and Bui, {Thi Hao} and Mikaella Rough and Alfonso Mucci and Canfield, {Donald Eugene} and Wing, {Boswell A.}",
year = "2015",
month = "1",
doi = "10.1016/j.gca.2014.11.007",
language = "English",
volume = "149",
pages = "152--164",
journal = "Geochimica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Pergamon Press",

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Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling : A case study from Mangrove Lake, Bermuda. / Pellerin, André ; Bui, Thi Hao; Rough, Mikaella; Mucci, Alfonso; Canfield, Donald Eugene; Wing, Boswell A.

I: Geochimica et Cosmochimica Acta, Bind 149, 01.2015, s. 152-164.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Mass-dependent sulfur isotope fractionation during reoxidative sulfur cycling

T2 - A case study from Mangrove Lake, Bermuda

AU - Pellerin, André

AU - Bui, Thi Hao

AU - Rough, Mikaella

AU - Mucci, Alfonso

AU - Canfield, Donald Eugene

AU - Wing, Boswell A.

PY - 2015/1

Y1 - 2015/1

N2 - The multiple sulfur isotope composition of porewater sulfate from the anoxic marine sapropel of Mangrove Lake, Bermuda was measured in order to establish how multiple sulfur isotopes are fractionated during reoxidative sulfur cycling. The porewater-sulfate δ34S and Δ33S dataset exhibits the distinct isotopic signatures of microbial sulfate reduction and sulfur reoxidation. We reproduced the measurements with a simple diagenetic model that yielded fractionation factors for net sulfate removal of between −29.2‰ and −32.5‰. A new approach to isotopic modeling of the sulfate profiles, informed by the chemistry of sulfur intermediate compounds in Mangrove Lake, reveals that sulfate reduction produces a relatively small intrinsic fractionation and that an active reoxidative sulfur cycle increases the fractionation of the measured values. Based on the model results, the reoxidative cycle of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80% of the sulfide produced by microbial sulfate reduction. The Mangrove Lake case study shows how sulfur isotope fractionations can be separated into three different “domains” in Δ33S–δ34S space based on their ability to resolve reductive and reoxidative sulfur transformations. The first domain that differentiates reductive and reoxidative sulfur cycling is well illustrated by previous studies and requires 34S–32S fractionations more negative than ≈−70‰, beyond the fractionation limit of microbial sulfate reduction at earth surface temperatures. The second domain that distinguishes reductive and reoxidative processes is between 34S–32S fractionations of −40‰ and 0‰, where the 33S–32S fractionations of sulfate reduction and reoxidation are significantly different. In the remaining domain (between 34S–32S fractionations −70‰ and −40‰), the similarity of the multiple sulfur isotope signals from microbial sulfate reduction and disproportionation means that the two processes cannot be discriminated from each other.

AB - The multiple sulfur isotope composition of porewater sulfate from the anoxic marine sapropel of Mangrove Lake, Bermuda was measured in order to establish how multiple sulfur isotopes are fractionated during reoxidative sulfur cycling. The porewater-sulfate δ34S and Δ33S dataset exhibits the distinct isotopic signatures of microbial sulfate reduction and sulfur reoxidation. We reproduced the measurements with a simple diagenetic model that yielded fractionation factors for net sulfate removal of between −29.2‰ and −32.5‰. A new approach to isotopic modeling of the sulfate profiles, informed by the chemistry of sulfur intermediate compounds in Mangrove Lake, reveals that sulfate reduction produces a relatively small intrinsic fractionation and that an active reoxidative sulfur cycle increases the fractionation of the measured values. Based on the model results, the reoxidative cycle of Mangrove Lake appears to include sulfide oxidation to elemental sulfur followed by the disproportionation of the elemental sulfur to sulfate and sulfide. This model also indicates that the reoxidative sulfur cycle of Mangrove Lake turns over from 50 to 80% of the sulfide produced by microbial sulfate reduction. The Mangrove Lake case study shows how sulfur isotope fractionations can be separated into three different “domains” in Δ33S–δ34S space based on their ability to resolve reductive and reoxidative sulfur transformations. The first domain that differentiates reductive and reoxidative sulfur cycling is well illustrated by previous studies and requires 34S–32S fractionations more negative than ≈−70‰, beyond the fractionation limit of microbial sulfate reduction at earth surface temperatures. The second domain that distinguishes reductive and reoxidative processes is between 34S–32S fractionations of −40‰ and 0‰, where the 33S–32S fractionations of sulfate reduction and reoxidation are significantly different. In the remaining domain (between 34S–32S fractionations −70‰ and −40‰), the similarity of the multiple sulfur isotope signals from microbial sulfate reduction and disproportionation means that the two processes cannot be discriminated from each other.

U2 - 10.1016/j.gca.2014.11.007

DO - 10.1016/j.gca.2014.11.007

M3 - Journal article

VL - 149

SP - 152

EP - 164

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

ER -