Mercury reduction and complexation by natural organic matter

Journal Article · Sat Jan 01 04:00:00 EST 2011 · Proceedings of the National Academy of Sciences

DOI:https://doi.org/10.1073/pnas.1008747108· OSTI ID:1008837

Gu, Baohua ^[1]; Bian, Yongrong ^[1]; Miller, Carrie L ^[1]; Dong, Wenming ^[1]; Jiang, Xin ^[2]; Liang, Liyuan ^[1]

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1. ORNL
2. Institute of Soil Science, China

Mercuric Hg(II) species form complexes with natural dissolved organic matter (DOM) such as humic acid (HA), and this binding is known to affect the chemical and biological transformation and cycling of mercury in aquatic environments. Dissolved elemental mercury, Hg(0), is also widely observed in sediments and water. However, reactions between Hg(0) and DOM have rarely been studied in anoxic environments. Here, under anoxic dark conditions we show strong interactions between reduced HA and Hg(0) through thiol-ligand induced oxidative complexation with an estimated binding capacity of about 3.5 umol Hg(0)/g HA and a partitioning coefficient greater than 10^6 mL/g. We further demonstrate that Hg(II) can be effectively reduced to Hg(0) in the presence of as little as 0.2 mg/L reduced HA, whereas production of purgeable Hg(0) is inhibited by complexation as HA concentration increases. This dual role played by DOM in the reduction and complexation of mercury is likely widespread in anoxic sediments and water and can be expected to significantly influence the mercury species transformations and biological uptake that leads to the formation of toxic methylmercury.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1008837
• Journal Information: Proceedings of the National Academy of Sciences, Journal Name: Proceedings of the National Academy of Sciences Journal Issue: 4 Vol. 108; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Biological reduction
CAPACITY
HUMIC ACIDS
MERCURY
METHYLMERCURY
ORGANIC MATTER
SEDIMENTS
SFA
STRONG INTERACTIONS
TRANSFORMATIONS
WATER
environmental factors
humic substances
methylation
redox