Atmospheric reactions of gaseous mercury with ozone and hydroxyl radical: Kinetics and product studies

The dominant form of mercury in the atmosphere is Hg-0. The oxidation processes are of great importance since oxidized mercury undergoes deposition and can become subject to bio-accumulation. Experimental data on the gaseous reactions of elemental mercury are very limited with compare to the reactions of Hg-0 in solutions. We herein carried out kinetic and product studies on the reactions of gaseous Hg-0 with O-3 and hydroxyl radical (HO) under near atmospheric pressure (750 +/- 1 Torr) and room temperature (298 +/- 1 K) in air and N-2. O-3 was produced in a silent discharge generator (OL 100/SB). Hydroxyl radicals were produced from the photolysis of isopropyl nitrite in the presence of NO. Kinetics of the reactions with WHO was studied using absolute and relative techniques by gas chromatography with mass spectroscopic detection (GC-MS). The gas phase reaction between elemental Hg-0 with O-3 has been studied in different surface-to-volume (s/v) ratios, and evidence for heterogeneous reactions was observed. Existence of mercuric oxide, HgO by the reaction of atomic Hg-0 with O-3 has been determined in the gas phase from the suspended aerosols using high temperature mass spectrometry.