Sulfide and iron control on mercury speciation in anoxic estuarine sediment slurries

Seunghee Han, Anna Obraztsova, Patrizia Pretto, Dimitri D. Deheyn, Joris Gieskes, Bradley Tebo

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

In order to understand the role of sulfate and Fe(III) reduction processes in the net production of monomethylmercury (MMHg), we amended anoxic sediment slurries collected from the Venice Lagoon, Italy, with inorganic Hg and either potential electron acceptors or metabolic byproducts of sulfate and Fe(III) reduction processes, gradually changing their concentrations. Addition of sulfide (final concentration: 0.2-6.3 mM) resulted in an exponential decrease in the sulfate reduction rate and MMHg concentration with increasing concentrations of sulfide. Based on this result, we argue that the concentration of dissolved sulfide is a critical factor controlling the sulfate reduction rate, and in turn, the net MMHg production at steady state. Addition of either Fe(II) (added concentration: 0-6.1 mM) or Fe(III) (added concentration: 0-3.5 mM) resulted in similar trends in the MMHg concentration, an increase with low levels of Fe additions and a subsequent decrease with high levels of Fe additions. The limited availability of dissolved Hg, associated with sulfide removal by precipitation of FeS, appears to inhibit the net MMHg production in high levels of Fe additions. There was a noticeable reduction in the net MMHg production in Fe(III)-amended slurries as compared to Fe(II)-amended ones, which could be caused by a decrease in the sulfate reduction rate. This agrees with the results of Hg methylation assays using the enrichment cultures of anaerobic bacteria: whereas the enrichment cultures of sulfate reducers showed significant production of MMHg (4.6% of amended Hg), those of Fe(III), Mn(IV), and nitrate reducers showed no production of MMHg. It appears that enhanced Fe(III)-reduction activities suppress the formation of MMHg in high sulfate estuarine sediments.

Original languageEnglish (US)
Pages (from-to)214-220
Number of pages7
JournalMarine Chemistry
Volume111
Issue number3-4
DOIs
StatePublished - Sep 16 2008

Fingerprint

anoxic sediment
estuarine sediment
Slurries
Sulfides
Mercury
Sulfates
Sediments
Iron
sulfide
sulfate
iron
Anoxic sediments
Methylation
methylation
mercury
Nitrates
Byproducts
Assays
lagoon
Bacteria

Keywords

  • Italy, Venice Lagoon
  • Mercury
  • Methyl mercury
  • Sediments
  • Sulfate reduction

ASJC Scopus subject areas

  • Chemistry(all)
  • Oceanography
  • Water Science and Technology
  • Environmental Chemistry

Cite this

Sulfide and iron control on mercury speciation in anoxic estuarine sediment slurries. / Han, Seunghee; Obraztsova, Anna; Pretto, Patrizia; Deheyn, Dimitri D.; Gieskes, Joris; Tebo, Bradley.

In: Marine Chemistry, Vol. 111, No. 3-4, 16.09.2008, p. 214-220.

Research output: Contribution to journalArticle

Han, Seunghee ; Obraztsova, Anna ; Pretto, Patrizia ; Deheyn, Dimitri D. ; Gieskes, Joris ; Tebo, Bradley. / Sulfide and iron control on mercury speciation in anoxic estuarine sediment slurries. In: Marine Chemistry. 2008 ; Vol. 111, No. 3-4. pp. 214-220.
@article{03a56d86e2374fa98fae6d8771d85a78,
title = "Sulfide and iron control on mercury speciation in anoxic estuarine sediment slurries",
abstract = "In order to understand the role of sulfate and Fe(III) reduction processes in the net production of monomethylmercury (MMHg), we amended anoxic sediment slurries collected from the Venice Lagoon, Italy, with inorganic Hg and either potential electron acceptors or metabolic byproducts of sulfate and Fe(III) reduction processes, gradually changing their concentrations. Addition of sulfide (final concentration: 0.2-6.3 mM) resulted in an exponential decrease in the sulfate reduction rate and MMHg concentration with increasing concentrations of sulfide. Based on this result, we argue that the concentration of dissolved sulfide is a critical factor controlling the sulfate reduction rate, and in turn, the net MMHg production at steady state. Addition of either Fe(II) (added concentration: 0-6.1 mM) or Fe(III) (added concentration: 0-3.5 mM) resulted in similar trends in the MMHg concentration, an increase with low levels of Fe additions and a subsequent decrease with high levels of Fe additions. The limited availability of dissolved Hg, associated with sulfide removal by precipitation of FeS, appears to inhibit the net MMHg production in high levels of Fe additions. There was a noticeable reduction in the net MMHg production in Fe(III)-amended slurries as compared to Fe(II)-amended ones, which could be caused by a decrease in the sulfate reduction rate. This agrees with the results of Hg methylation assays using the enrichment cultures of anaerobic bacteria: whereas the enrichment cultures of sulfate reducers showed significant production of MMHg (4.6{\%} of amended Hg), those of Fe(III), Mn(IV), and nitrate reducers showed no production of MMHg. It appears that enhanced Fe(III)-reduction activities suppress the formation of MMHg in high sulfate estuarine sediments.",
keywords = "Italy, Venice Lagoon, Mercury, Methyl mercury, Sediments, Sulfate reduction",
author = "Seunghee Han and Anna Obraztsova and Patrizia Pretto and Deheyn, {Dimitri D.} and Joris Gieskes and Bradley Tebo",
year = "2008",
month = "9",
day = "16",
doi = "10.1016/j.marchem.2008.05.002",
language = "English (US)",
volume = "111",
pages = "214--220",
journal = "Marine Chemistry",
issn = "0304-4203",
publisher = "Elsevier",
number = "3-4",

}

TY - JOUR

T1 - Sulfide and iron control on mercury speciation in anoxic estuarine sediment slurries

AU - Han, Seunghee

AU - Obraztsova, Anna

AU - Pretto, Patrizia

AU - Deheyn, Dimitri D.

AU - Gieskes, Joris

AU - Tebo, Bradley

PY - 2008/9/16

Y1 - 2008/9/16

N2 - In order to understand the role of sulfate and Fe(III) reduction processes in the net production of monomethylmercury (MMHg), we amended anoxic sediment slurries collected from the Venice Lagoon, Italy, with inorganic Hg and either potential electron acceptors or metabolic byproducts of sulfate and Fe(III) reduction processes, gradually changing their concentrations. Addition of sulfide (final concentration: 0.2-6.3 mM) resulted in an exponential decrease in the sulfate reduction rate and MMHg concentration with increasing concentrations of sulfide. Based on this result, we argue that the concentration of dissolved sulfide is a critical factor controlling the sulfate reduction rate, and in turn, the net MMHg production at steady state. Addition of either Fe(II) (added concentration: 0-6.1 mM) or Fe(III) (added concentration: 0-3.5 mM) resulted in similar trends in the MMHg concentration, an increase with low levels of Fe additions and a subsequent decrease with high levels of Fe additions. The limited availability of dissolved Hg, associated with sulfide removal by precipitation of FeS, appears to inhibit the net MMHg production in high levels of Fe additions. There was a noticeable reduction in the net MMHg production in Fe(III)-amended slurries as compared to Fe(II)-amended ones, which could be caused by a decrease in the sulfate reduction rate. This agrees with the results of Hg methylation assays using the enrichment cultures of anaerobic bacteria: whereas the enrichment cultures of sulfate reducers showed significant production of MMHg (4.6% of amended Hg), those of Fe(III), Mn(IV), and nitrate reducers showed no production of MMHg. It appears that enhanced Fe(III)-reduction activities suppress the formation of MMHg in high sulfate estuarine sediments.

AB - In order to understand the role of sulfate and Fe(III) reduction processes in the net production of monomethylmercury (MMHg), we amended anoxic sediment slurries collected from the Venice Lagoon, Italy, with inorganic Hg and either potential electron acceptors or metabolic byproducts of sulfate and Fe(III) reduction processes, gradually changing their concentrations. Addition of sulfide (final concentration: 0.2-6.3 mM) resulted in an exponential decrease in the sulfate reduction rate and MMHg concentration with increasing concentrations of sulfide. Based on this result, we argue that the concentration of dissolved sulfide is a critical factor controlling the sulfate reduction rate, and in turn, the net MMHg production at steady state. Addition of either Fe(II) (added concentration: 0-6.1 mM) or Fe(III) (added concentration: 0-3.5 mM) resulted in similar trends in the MMHg concentration, an increase with low levels of Fe additions and a subsequent decrease with high levels of Fe additions. The limited availability of dissolved Hg, associated with sulfide removal by precipitation of FeS, appears to inhibit the net MMHg production in high levels of Fe additions. There was a noticeable reduction in the net MMHg production in Fe(III)-amended slurries as compared to Fe(II)-amended ones, which could be caused by a decrease in the sulfate reduction rate. This agrees with the results of Hg methylation assays using the enrichment cultures of anaerobic bacteria: whereas the enrichment cultures of sulfate reducers showed significant production of MMHg (4.6% of amended Hg), those of Fe(III), Mn(IV), and nitrate reducers showed no production of MMHg. It appears that enhanced Fe(III)-reduction activities suppress the formation of MMHg in high sulfate estuarine sediments.

KW - Italy, Venice Lagoon

KW - Mercury

KW - Methyl mercury

KW - Sediments

KW - Sulfate reduction

UR - http://www.scopus.com/inward/record.url?scp=53649108508&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=53649108508&partnerID=8YFLogxK

U2 - 10.1016/j.marchem.2008.05.002

DO - 10.1016/j.marchem.2008.05.002

M3 - Article

AN - SCOPUS:53649108508

VL - 111

SP - 214

EP - 220

JO - Marine Chemistry

JF - Marine Chemistry

SN - 0304-4203

IS - 3-4

ER -