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Photochemical reactions between mercury (Hg) and dissolved organic matter decrease Hg bioavailability and methylation.

Authors :
Luo HW
Yin X
Jubb AM
Chen H
Lu X
Zhang W
Lin H
Yu HQ
Liang L
Sheng GP
Gu B
Source :
Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2017 Jan; Vol. 220 (Pt B), pp. 1359-1365. Date of Electronic Publication: 2016 Nov 09.
Publication Year :
2017

Abstract

Atmospheric deposition of mercury (Hg) to surface water is one of the dominant sources of Hg in aquatic environments and ultimately drives methylmercury (MeHg) toxin accumulation in fish. It is known that freshly deposited Hg is more readily methylated by microorganisms than aged or preexisting Hg; however the underlying mechanism of this process is unclear. We report that Hg bioavailability is decreased by photochemical reactions between Hg and dissolved organic matter (DOM) in water. Photo-irradiation of Hg-DOM complexes results in loss of Sn(II)-reducible (i.e. reactive) Hg and up to an 80% decrease in MeHg production by the methylating bacterium Geobacter sulfurreducens PCA. Loss of reactive Hg proceeded at a faster rate with a decrease in the Hg to DOM ratio and is attributed to the possible formation of mercury sulfide (HgS). These results suggest a new pathway of abiotic photochemical formation of HgS in surface water and provide a mechanism whereby freshly deposited Hg is readily methylated but, over time, progressively becomes less available for microbial uptake and methylation.<br /> (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Details

Language :
English
ISSN :
1873-6424
Volume :
220
Issue :
Pt B
Database :
MEDLINE
Journal :
Environmental pollution (Barking, Essex : 1987)
Publication Type :
Academic Journal
Accession number :
27836473
Full Text :
https://doi.org/10.1016/j.envpol.2016.10.099