Sulfur Chemistry
Air quality (health effects of particulate matter)
Ecosystems: Acid Rain
London Smog 1952
Climate
Visibility
Major Reservoirs and Burdens of Sulfur (TgS)
1
Global Sulfur Emission Estimates (TgS /yr)
Sources
Compound
Emissions
Oceans (without sea-salt)
Volcanoes
Plants + Soils
Fossil Fuel Combustion
(+industry)
Biomass Burning
DMS (CS2, OCS)
SO2, SO42- (H2S, OCS)
SO42-, H2S (DMS, CS2)
SO2 (SO42-, H2S, CS2)
15-25
9-12
0.2-1
70-80
SO2 (SO42-, OCS)
Total
2-3
98-120
SO2, SO42SO2, SO42-
50-60
50-60
Sinks
Dry Deposition
Wet Deposition
Seinfeld & Pandis, 1998.
GLOBAL SULFUR BUDGET
(flux terms in Tg S yr-1)
COS
stratosphere
troposphere
hν,OH
SO2
OH
cloud
42
NO3
18
SO42-
OH
SO2
4
SO42-
H2SO4(g)
τ = 1.3d
8
H2SO4(g)
τ = 3.9d
OH
(CH3)2S
(DMS)
τ = 1.0d
1
10
64
dep
27 dry
20 wet
dep
6 dry
44 wet
22
Phytoplankton Oceans
Volcanoes
Combustion
Smelters
2
CARBONYL SULFIDE (COS)
Tropospheric Oxidation,
Stratospheric Photolysis
Sources ~ 1 Tg/yr
Lifetime ~ 7 years
COS
500 pptv
Oxidation
CS2
DMS
PLANTS
SOILS
Biomass
Burning
OCEAN
ANTHROPOGENIC
Slide from Parv Suntharalingam
Dimethyl Sulfide (DMS)
DMS formed from breakdown of
DMSP (dimethyl sulfoniopropionate)
Yoch, Appl. Env. Microbio., 2002.
3
DMS Annual Sea surface concentrations
Kettle et al., Glob. Biogeochemical Cycles, 1999.
Mechanism for OH reaction of dimethyl sulfide (DMS)
DMS
Lifetime ~ 1 day
DMSO
MSA = methane sulfonic acid
DMSO = dimethyl sulfoxide
~75%
~25%
DMSO2
Also loss by reaction with NO3 (nighttime) Æ SO2
MSA
Seinfeld & Pandis, 1998.
H2SO4
4
Trends in Anthropogenic Sulfur emissions (1850-2000)
Stern, Chemosphere 58 (2005)
Recent Trends in Sulfur Emissions (1980-2000)
Stern, Chemosphere 58 (2005)
5
GLOBAL SULFUR EMISSION TO THE ATMOSPHERE
1990 annual mean
Chin et al. [2000]
Oxidation of SO2
• Gas-phase oxidation of SO2 (~15% of total
oxidation)
• Aqueous phase oxidation of SO2 (~85% of total
oxidation)
6
Surface
JJA
MSA
DMS
DJF
Chin et al., JGR, 2000.
500 mbar
JJA
MSA
DMS
DJF
Mixing ratios in pptv
Chin et al., JGR, 2000.
Mixing ratios in pptv
7
Surface
JJA
sulfate
SO2
DJF
Chin et al., JGR, 2000.
500 mbar
JJA
sulfate
SO2
DJF
Mixing ratios in pptv
Chin et al., JGR, 2000.
Mixing ratios in pptv
8