Oxidation of Gaseous Elemental Mercury in Acidified Water: Evaluation of Possible Sinking Pathway of Atmospheric Gaseous Mercury in Acid Cloud, Fog, and Rain Droplets

This is the first report investigating transformation of gaseous elemental mercury (GEM), major form airborne mercury, into oxidized in bulk liquid, a possible sinking pathway atmospheric GEM clouds, fog, rain droplets and ocean spray. A 100–150 ng m−3 standard gas, 50–150 times higher concentration than typical concentration, was introduced 2.5 L rectangular glass vessel, at bottom which 0.5 uptake solution pure water (pH 6–7), weakly acidified with sulfuric or nitric acid 3.2–3.6) seawater 8) resting. The gas space above vessel rate 0.82 min−1 exited from opposite end open to room’s pressure. After exposing for 0.5–4 h, portion sampled, dissolved (Hg0aq) (Hg2+aq) were analyzed by conventional trapping method, followed cold vapor atomic fluorescent spectrometer measurements. results showed that quantities total (THgaq = Hg0aq + Hg2+aq) compatible, but those slightly lower equilibrated concentrations estimated Henry’s law, suggesting non-equilibrium throughout whole solution. In contrast, quantity Hg2+aq THgaq significantly enhanced. Over 4 h exposure, two concentration. due slow oxidation reaction phase. Using collision surface observed uptake, coefficient this (5.5 ± 1.6) × 10−6. Under magnitude an lifetime 4970 years, negligibly small compared other processes.