Biogeochemical factors affecting mercury methylation in sediments of the Venice Lagoon, Italy

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

Research output: Contribution to journalArticle

55 Citations (Scopus)

Abstract

Mercury methylation and sulfate reduction rates, total Hg, and monomethyl Hg in the sediments of the Venice Lagoon (Italy) were measured in June 2005 in order to identify the factors affecting the methylation of inorganic Hg. While the rates of Hg methylation and sulfate reduction were generally higher in the surface layers (0-2.5 cm), the correlation between Hg methylation and sulfate reduction rates was not significant when considering all depths and sites. This discrepancy is discussed considering two factors: the activity of sulfate-reducing bacteria and Hg solubility. The former factor is important in determining the Hg methylation rate in comparable geochemical conditions as evidenced by similar vertical profiles of Hg methylation and sulfate reduction rates in each sediment core. The latter factor was assessed by comparing the Hg methylation rate with the particle-water partition coefficient of Hg. The Hg methylation rates normalized to sulfate reduction rates showed a negative linear correlation with the logarithm of the particle-water partition coefficient of Hg, suggesting that the availability of dissolved Hg is a critical factor affecting Hg methylation. Solid FeS seems to play an important role in controlling the solubility of Hg in Venice Lagoon sediments, where sulfate and iron reductions are the dominant electron-accepting processes. Overall, the production of monomethyl Hg in the Venice Lagoon is controlled by a fine balance between microbial and geochemical processes with key factors being the microbial sulfate reduction rate and the availability of dissolved Hg.

Original languageEnglish (US)
Pages (from-to)655-663
Number of pages9
JournalEnvironmental Toxicology and Chemistry
Volume26
Issue number4
DOIs
StatePublished - Apr 2007

Fingerprint

Methylation
methylation
Mercury
Italy
lagoon
Sediments
Sulfates
sulfate
sediment
partition coefficient
Solubility
solubility
Availability
rate
mercury
Water
sulfate-reducing bacterium
vertical profile
sediment core
surface layer

Keywords

  • Mercury
  • Methylation
  • Sediment
  • Sulfate reduction
  • Venice Lagoon

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry
  • Toxicology
  • Health, Toxicology and Mutagenesis

Cite this

Biogeochemical factors affecting mercury methylation in sediments of the Venice Lagoon, Italy. / Han, Seunghee; Obraztsova, Anna; Pretto, Patrizia; Choe, Key Young; Gieskes, Joris; Deheyn, Dimitri D.; Tebo, Bradley.

In: Environmental Toxicology and Chemistry, Vol. 26, No. 4, 04.2007, p. 655-663.

Research output: Contribution to journalArticle

Han, Seunghee ; Obraztsova, Anna ; Pretto, Patrizia ; Choe, Key Young ; Gieskes, Joris ; Deheyn, Dimitri D. ; Tebo, Bradley. / Biogeochemical factors affecting mercury methylation in sediments of the Venice Lagoon, Italy. In: Environmental Toxicology and Chemistry. 2007 ; Vol. 26, No. 4. pp. 655-663.
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