Mercury isotope fractionation during photoreduction in natural water is controlled by its Hg/DOC ratio

Zheng, Wang; Hintelmann, Holger

doi:10.1016/j.gca.2009.08.016

Cited by 296 publications

(402 citation statements)

References 63 publications

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“…Hg II could form strong complexes with organic ligands such as reduced sulfur groups [74,[83][84][85]. The photoreduction of Hg II in the presence of dissolved organic matter (DOM) has been widely documented in various natural water systems [86][87][88][89][90] and may also occur in atmospheric droplets and organic aerosols (OA) [91].…”

Section: Photoreduction Of Hg II -Organic Complexesmentioning

confidence: 99%

Recent Advances in Atmospheric Chemistry of Mercury

Ariya

2018

Atmosphere

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Mercury is one of the most toxic metals and has global importance due to the biomagnification and bioaccumulation of organomercury via the aquatic food web. The physical and chemical transformations of various mercury species in the atmosphere strongly influence their composition, phase, transport characteristics and deposition rate to the ground. Modeling efforts to evaluate the mercury cycling in the environment require an accurate understanding of atmospheric mercury chemistry. We focus this article on recent studies (since 2015) on improving our understanding of the atmospheric chemistry of mercury. We discuss recent advances in (i) determining the dominant atmospheric oxidant of elemental mercury (Hg 0 ); (ii) understanding the oxidation reactions of Hg 0 by halogen atoms and by nitrate radical (NO 3 ); (iii) the aqueous reduction of oxidized mercury compounds (Hg II ); and (iv) the heterogeneous reactions of Hg on atmospherically-relevant surfaces. The need for future research to improve understanding of the fate and transformation of mercury in the atmosphere is also discussed.

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Section: Photoreduction Of Hg II -Organic Complexesmentioning

confidence: 99%

Recent Advances in Atmospheric Chemistry of Mercury

Ariya

2018

Atmosphere

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“…The HO 2 aqueous-phase reduction mechanism is widely believed to be unlikely under normal environmental conditions [17,32,53]. These results from a more likely reduction mechanism, the DCA case, will be more useful and physically meaningful in future applications than applying tuned empirical reduction rates or a mechanism that is unlikely under typical ambient environmental conditions.…”

Section: Discussionmentioning

confidence: 99%

Regional Air Quality Model Application of the Aqueous-Phase Photo Reduction of Atmospheric Oxidized Mercury by Dicarboxylic Acids

et al. 2013

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Abstract:In most ecosystems, atmospheric deposition is the primary input of mercury. The total wet deposition of mercury in atmospheric chemistry models is sensitive to parameterization of the aqueous-phase reduction of divalent oxidized mercury (Hg 2+ ). However, most atmospheric chemistry models use a parameterization of the aqueous-phase reduction of Hg 2+ that has been shown to be unlikely under normal ambient conditions or use a non mechanistic value derived to optimize wet deposition results. Recent laboratory experiments have shown that Hg 2+ can be photochemically reduced to elemental mercury (Hg) in the aqueous-phase by dissolved organic matter and a mechanism and the rate for Hg 2+ photochemical reduction by dicarboxylic acids (DCA) has been proposed. For the first time in a regional scale model, the DCA mechanism has been applied. The HO 2 -Hg 2+ reduction mechanism, the proposed DCA reduction mechanism, and no aqueous-phase reduction (NAR) of Hg 2+ are evaluated against weekly wet deposition totals, concentrations and precipitation observations from the Mercury Deposition Network (MDN) using the Community Multiscale Air Quality (CMAQ) model version 4.7.1. Regional scale simulations of mercury wet deposition using a DCA reduction mechanism evaluated well against observations, and reduced the bias in model evaluation by at least 13% over the other schemes evaluated, although summertime deposition estimates were still biased by −31.4% against observations. The use of the DCA reduction mechanism

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“…The extent of MMHg photodegradation, prior to the MMHg entering the food web, can be quantified from experimental relationships that are sensitive to parameters such as dissolved organic carbon (DOC) concentration, 30,75 MMHg:DOC ratios, 73 and the wavelength of incident radiation. 76 We use different experimental relationships for Cache Creek and Yolo Bypass to account for differences in reported DOC concentrations.…”

Section: Mmhg Photodegradationmentioning

confidence: 99%