Exchange Reactions Alter Molecular Speciation of Gaseous Oxidized Mercury
Document Type
Article
Publication Date
8-19-2021
Abstract
The knowledge of speciation of gaseous oxidized mercury (GOM) is crucial for understanding the atmospheric mercury chemistry and global cycle. Because of the low atmospheric abundance of GOM, its chemical analysis requires preconcentration and often involves the use of collection substrates, such as KCl, various adsorbents, or membranes. GOM molecules adsorbed on substrates can exchange ligands with the substrate material, each other, or other coadsorbed atmospheric chemicals, altering the composition of GOM and ultimately leading to speciation biases. Here, we investigated exchange reactions involving GOM surrogates HgBr2, HgCl2, and Hg(NO3)2 and different forms of Cl- (as KCl, NH4Cl, and HCl). The reactions were studied in aqueous solutions and on surfaces, and the products were analyzed in the gas phase (by ion drift-chemical ionization mass spectrometry), in solution (by electrospray ionization-mass spectrometry), and on surface (by Raman microscopy). In all cases, we observed a rapid formation of exchange products HgBrCl and HgCl2, which readily volatilized not only upon heating, but also often at room temperature, depending on substrate adsorptivity. We propose that a similar exchange may occur both on atmospheric aerosols and during analysis, where the original GOM species (e.g., BrHgONO and BrHgOOH) would react on surfaces/particles with each other and atmospherically abundant trace species to form other mercury(II) chemicals. For example, a readily volatilizable HgCl2 can be produced through the exchange with chloride.
Identifier
85113738869 (Scopus)
Publication Title
ACS Earth and Space Chemistry
External Full Text Location
https://doi.org/10.1021/acsearthspacechem.1c00178
e-ISSN
24723452
First Page
1842
Last Page
1853
Issue
8
Volume
5
Grant
AGS-1554777
Fund Ref
National Science Foundation
Recommended Citation
Mao, Na and Khalizov, Alexei, "Exchange Reactions Alter Molecular Speciation of Gaseous Oxidized Mercury" (2021). Faculty Publications. 3874.
https://digitalcommons.njit.edu/fac_pubs/3874