TY - JOUR
T1 - Reactions of gaseous mercury with atomic and molecular halogens
T2 - Kinetics, product studies, and atmospheric implications
AU - Ariya, Parisa A.
AU - Khalizov, Alexei
AU - Gidas, Alexios
PY - 2002/8/15
Y1 - 2002/8/15
N2 - Rapid depletions of atmospheric mercury (Hg0) and ozone coinciding with high halogen concentrations have recently been observed in several high-Arctic and sub-Arctic regions. The lack of kinetic data on the halogen-initiated reactions of elemental mercury precluded the drawing of any conclusions on the chemistry of these mercury depletion events. We carried out extensive kinetic and product studies on the reactions of gaseous Hg0 with molecular and atomic halogens (X/X2 where X = Cl, Br) at atmospheric pressure (750 ± 1 Torr) and room temperature (298 ± 1 K) in air and N2. Kinetics of the reactions with X/X2 was studied using relative and absolute techniques by cold vapor atomic absorption spectroscopy (CVAAS) and gas chromatography with mass spectroscopic detection (GC-MS). The measured rate constants for reactions of Hg0 with Cl2, Cl, Br2, and Br were (2.6 ± 0.2) × 10-18, (1.0 ± 0.2) × 10-11, <(0.9 ± 0.2) × 10-16, and (3.2 ± 0.3) × 10-12 cm3 molecule-1 s-1 respectively. The reaction products were analyzed in the gas phase, from the suspended aerosols, and from the wall of the reactor using MS, GC-MS, and inductively coupled plasma mass spectrometry (ICP-MS). The major products identified were HgCl2 and HgBr2 adsorbed on the wall. Suspended aerosols, collected on the micron filters, contributed to less than 0.5% of the reaction products under our experimental conditions. The importance of halogen reactions of mercury in the formation of particulate matter, which tends to be bioaccumulative, is discussed herein.
AB - Rapid depletions of atmospheric mercury (Hg0) and ozone coinciding with high halogen concentrations have recently been observed in several high-Arctic and sub-Arctic regions. The lack of kinetic data on the halogen-initiated reactions of elemental mercury precluded the drawing of any conclusions on the chemistry of these mercury depletion events. We carried out extensive kinetic and product studies on the reactions of gaseous Hg0 with molecular and atomic halogens (X/X2 where X = Cl, Br) at atmospheric pressure (750 ± 1 Torr) and room temperature (298 ± 1 K) in air and N2. Kinetics of the reactions with X/X2 was studied using relative and absolute techniques by cold vapor atomic absorption spectroscopy (CVAAS) and gas chromatography with mass spectroscopic detection (GC-MS). The measured rate constants for reactions of Hg0 with Cl2, Cl, Br2, and Br were (2.6 ± 0.2) × 10-18, (1.0 ± 0.2) × 10-11, <(0.9 ± 0.2) × 10-16, and (3.2 ± 0.3) × 10-12 cm3 molecule-1 s-1 respectively. The reaction products were analyzed in the gas phase, from the suspended aerosols, and from the wall of the reactor using MS, GC-MS, and inductively coupled plasma mass spectrometry (ICP-MS). The major products identified were HgCl2 and HgBr2 adsorbed on the wall. Suspended aerosols, collected on the micron filters, contributed to less than 0.5% of the reaction products under our experimental conditions. The importance of halogen reactions of mercury in the formation of particulate matter, which tends to be bioaccumulative, is discussed herein.
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U2 - 10.1021/jp020719o
DO - 10.1021/jp020719o
M3 - Article
AN - SCOPUS:0037101832
SN - 1089-5639
VL - 106
SP - 7310
EP - 7320
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 32
ER -