A Theoretical Study on the Reactions of Hg with Halogens: Atmospheric Implications.

Khalizov, Alexei F.; Viswanathan, Balakrishnan; Larrégaray, P.; Ariya, Parisa A.

doi:10.1002/chin.200343005

Cited by 11 publications

(17 citation statements)

References 34 publications

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“…Previous laboratory studies reported apparent rate coefficients in the range of (3.6 ± 0.9) × 10 −13 to (3.2 ± 0.3) × 10 −12 cm 3 molec −1 s −1 , at 1 atm and 298 K [19,20,22]. Theoretical studies estimated the rate constants to be from 9.8 × 10 −13 to 2.1 × 10 −12 cm 3 molec −1 s −1 , at 1 atm and 298 K [3,21,23]. Theoretical and experimental rate constants for mercury oxidation by Br and Cl atoms at 298 K have previously been compared in detail in Table A.2 by Subir et al [18].…”

Section: Br-initiated Oxidation Of Hgmentioning

confidence: 96%

“…Here we discuss recent advances in the understanding of the oxidation of Hg 0 by halogen atoms and NO3 radicals, as well as determining the major oxidant(s) in the atmosphere. Adapted and modified from [3]. The question mark (?)…”

Section: Chemical Redox Pathways In the Gas Phasementioning

confidence: 99%

“…Due to the rather long lifetime of atmospheric mercury, once mercury compounds are released into the atmosphere, they can be transported around the globe. As such, they not only have local impacts but also regional and global implications [2,3].…”

Section: Introductionmentioning

confidence: 99%

“…Global modeling studies also suggest that large uncertainties exist in our current knowledge of the global cycling of mercury [15]. Adapted and modified from [3]. The question mark (?)…”

Section: Introductionmentioning

confidence: 99%

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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: Br-initiated Oxidation Of Hgmentioning

confidence: 96%

Section: Chemical Redox Pathways In the Gas Phasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Global modeling studies also suggest that large uncertainties exist in our current knowledge of the global cycling of mercury [15]. Adapted and modified from [3]. The question mark (?)…”

Section: Introductionmentioning

confidence: 99%

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Recent Advances in Atmospheric Chemistry of Mercury

Ariya

2018

Atmosphere

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“…Other theoretical [Khalizov et al, 2003;Goodsite et al, 2004] and experimental [Ariya et al, 2002] estimates of k 1 are faster (see Table 1), although Donohoue et al [2006] argue that these values are less accurate. The fastest k 1 value with reported temperature dependence [Khalizov et al, 2003] implies t global = 160 days, after recalculating k 2 to keep the k 1 :k 2 balance [Goodsite et al, 2004].…”

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confidence: 99%

Global lifetime of elemental mercury against oxidation by atomic bromine in the free troposphere

Holmes

Jacob

Yang

2006

Geophysical Research Letters

216

237

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[1] We calculate the global mean atmospheric lifetime of elemental mercury (Hg 0 ) against oxidation by atomic bromine (Br) in the troposphere by combining recent kinetic data for the Hg-Br system with modeled global concentrations of tropospheric Br. We obtain a lifetime of 0.5-1.7 years based on the range of kinetic data, implying that oxidation of Hg 0 by Br is a major, and possibly dominant, global sink for Hg 0 . Most of the oxidation takes place in the middle and upper troposphere, where Br concentrations are high and where cold temperatures suppress thermal decomposition of the HgBr intermediate. This oxidation mechanism is consistent with mercury observations, including in particular high gaseous Hg(II) concentrations in Antarctic summer. Better freetropospheric measurements of bromine radicals and further kinetic study of the Hg-Br system are essential to more accurately assess the global importance of Br as an oxidant of atmospheric Hg 0 . Citation:

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Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

Knecht

Fux

Meer³

et al. 2011

Theor Chem Acc

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The electrostatic contribution to the Mössbauer isomer shift of mercury for the series HgF n (n = 1, 2, 4) with respect to the neutral atom has been investigated in the framework of four-and two-component relativistic theory. Replacing the integration of the electron density over the nuclear volume by the contact density (that is, the electron density at the nucleus) leads to a 10% overestimation of the isomer shift. The systematic nature of this error suggests that it can be incorporated into a correction factor, thus justifying the use of the contact density for the calculation of the Mössbauer isomer shift. The performance of a large selection of density functionals for the calculation of contact densities has been assessed by comparing with finite-field four-component relativistic coupled-cluster with single and double and perturbative triple excitations [CCSD(T)] calculations. For the absolute contact density of the mercury atom, the Density Functional Theory (DFT) calculations are in error by about 0.5%, a result that must be judged against the observation that the change in contact density along the series HgF n (n = 1, 2, 4), relevant for the isomer shift, is on the order of 50 ppm with respect to absolute densities. Contrary to previous studies of the 57 Fe isomer shift (F Neese, Inorg Chim Acta 332:181, 2002), for mercury, DFT is not able to reproduce the trends in the isomer shift provided by reference data, in our case CCSD(T) calculations, notably the non-monotonous decrease in the contact density along the series HgF n (n = 1, 2, 4). Projection analysis shows the expected reduction of the 6s 1/2 population at the mercury center with an increasing number of ligands, but also brings into light an opposing effect, namely the increasing polarization of the 6s 1/2 orbital due to increasing effective charge of the mercury atom, which explains the nonmonotonous behavior of the contact density along the series. The same analysis shows increasing covalent contributions to bonding along the series with the effective charge of the mercury atom reaching a maximum of around ?2 for HgF 4 at the DFT level, far from the formal charge ?4 suggested by the oxidation state of this recently observed species. Whereas the geometries for the linear HgF 2 and square-planar HgF 4 molecules were taken from previous computational studies, we optimized the equilibrium distance of HgF at the four-component Fock-space CCSD/aug-cc-pVQZ level, giving spectroscopic constants r e = 2.007 Å and x e = 513.5 cm -1 .Dedicated to Professor Pekka Pyykkö on the occasion of his 70th birthday and published as part of the Pyykkö Festschrift Issue.Electronic supplementary material The online version of this article

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A Theoretical Study on the Reactions of Hg with Halogens: Atmospheric Implications.

Cited by 11 publications

References 34 publications

Recent Advances in Atmospheric Chemistry of Mercury

Recent Advances in Atmospheric Chemistry of Mercury

Global lifetime of elemental mercury against oxidation by atomic bromine in the free troposphere

Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

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