Gaseous deposition to snow 2. Physical-chemical model for SO/sub 2/ deposition

Journal Article · Thu Aug 20 04:00:00 EDT 1987 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JD092iD08p09789· OSTI ID:5979874

Bales, R C; Valdez, M P; Dawson, G A

A diffusion/reaction model of SO/sub 2/ uptake by snow containing liquid water is used to examine the snowpack processes controlling accumulation of dissolved S(IV) and S(VI). Surface deposition velocity v/sub d/ (defined as overall accumulation rate divided by surface SO/sub 2/ concentration) depends on the amount of liquid water in the snow, the time scale considered, the rate of S(IV) to S(VI) conversion in the aqueous phase, and the SO/sub 2/ concentration. In the absence of any oxidation, v/sub d/ for dense snow (specific gravity 0.4) with a moderate liquid water mass fraction (X/sub m/ = 0.01) and SO/sub 2/ concentration of 20 ppbv (parts per billion by volume) is calculated to be 0.026 cm s/sup -1/ after 6 hours. Deposition velocity increases by a factor of 3.2 for each tenfold increase in X/sub m/ and by a factor of 2.5--3.2 for each tenfold decrease in time. SO/sub 2/ penetration into the snowpack is about 5 cm for the 6--hour case. In the presence of air containing 30 ppbv ozone and otherwise identical conditions, 80% of the accumulated sulfur is as S(VI), and the calculated v/sub d/ is 0.036 cm s/sup -1/. A further tenfold increase in ozone concentration gives only a 70% increase in v/sub d/. A similar dependence is calculated for oxygen (catalyzed by Fe(III)) as oxidant, but that for hydrogen peroxide is much stronger and almost linear. A tenfold increase in SO/sub 2/ concentration (with ozone at 30 ppb) results in a 2.3-fold decrease in v/sub d/. Wet snow with a liquid water mass fraction of about 0.1 gives a deposition velocity at 20 ppb SO/sub 2/ of 0.12 cm s/sup -1/, with a penetration of only 2 cm. Calculated and observed uptakes of SO/sub 2/ by snow are in good agreement. copyrightAmerican Geophysical Union 1987

• Research Organization: Department of Hydrology and Water Resources, University of Arizona, Tucson
• OSTI ID: 5979874
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 92:D8; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
ATMOSPHERIC PRECIPITATIONS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
DEPOSITION
DIFFUSION
FLUIDS
HYDROGEN COMPOUNDS
LIQUIDS
MATHEMATICAL MODELS
OXIDES
OXYGEN COMPOUNDS
OZONE
POLLUTION
QUANTITY RATIO
SNOW
SULFUR COMPOUNDS
SULFUR DIOXIDE
SULFUR OXIDES
VELOCITY
WATER