Transcript Gregory R. Carmichael - UNC Institute for the Environment

Climatic Effects & Air Quality:
Aerosol/Chemistry Interactions and the Role of
Megacities
Gregory R. Carmichael
Center for Global and Regional Environmental Research, The University of Iowa, Iowa City, USA
Aerosols are Pervasive Throughout Asian
Environments
Mineral Dust
BC from Pollution & Fires
A Key Science Issue: Chemistry/Aerosol/Regional
Climate Coupling
Radiative Forcing
Anthropogenic
Generation of
inorganic and
organic
aerosols by
gas-to-particle
conversion
and
nucleation
Biogenic
Tropospheric O3
Stratospheric input
Flux of gaseous
species to clouds
Gas-phase Tropospheric
Chemistry
Heterogeneous
NOx/NOy
chemistry
Free radical
Scavenging ?
Alteration of
Actinic flux
Tropospheric
Aerosols
Direct
effect
NH3
Sea salt
Mineral dust
Biomass burning particles
Sulfates (via gas-phase chemistry)
Carbonaceous particles
Cloud
processing
Tropospheric
Clouds
Cirrus
Stratus
CCN
Alteration of
cloud albedo
(indirect effect)
Radiative Forcing
modified after J.H.Seinfeld 1999
Mineral Aerosol Perturb Trace Gas Cycles
in Many Ways
•
•
•
•
Increase SO2 to sulfate conversion rates.
Increase the importance of dry deposition.
Decrease the lifetime of SOx, NOy and VOC?
Control the partitioning of semi-volatile species (e.g.,
HNO3).
• Influence precipitation pH.
• Provide reaction channels which may: recycle Nox;
produce particulate nitrate; make longer chain VOCs;
provide radical sources; and indirectly/directly Perturb O3;
and alter water uptake.
• Alter photolysis rates.
THE APPROACH
MODELING
LABORATORY
(Vicki Grassian
–leader)
FIELD
STUDY
Chemical Role of
Aerosol Particles in the
Atmosphere
Can change the chemical balance of the
atmosphere in two ways
Sink
NO2 +
NO2
Reactive Surface
•3D STEM-III
transport/chemistry/deposition model
•Dynamics of Aerosol Processes
•Combined Kinetic/Thermodynamic
Approach
•New Approach for Secondary
Organic Aerosol Partitioning
•Sensitivity Analysis and Improved
Numerical Methods
O
•Spectroscopic Measurements
•Detailed Reaction Mechanisms
NO2 +
+ NO
•Kinetic Measurements
•Surface Coverages
• Adsorption Isotherms
H(a) + NO2
HONO
INTERACTIONS OF SO2 WITH MINERAL AEROSOL CHANGE
SULFATE SIZE DISTRIBUTION AS WELL AS THE CHEMICAL
LIFETIMES OF SULFUR. THESE INTERACTIONS HAVE
IMPLICATIONS FOR RADIATIVE FORCING
Song et al., JGR in press
Calculated Fine and Coarse Mode Aerosol Distributions in
the Boundary Layer; PEM-WEST B
Calculated Fine and Coarse Mode Aerosol Distributions in the
Boundary Layer; PEM-WEST B
Calculated Fine and Coarse Mode Aerosol Distributions at 5 km;
PEM-WEST B
Calculated Fine and Coarse Mode Aerosol Distributions at 5 km;
PEM-WEST B
% Decrease in HO2 levels due to RXNs on Mineral Aerosol
(May 1987)
% Change in O3 in May 1987 due to:
NOx + HxOy Rxns;
Direct O3 Rxn; and Combination
Nitric Acid Reactions with Calcium Carbonate are not Limited to
the Surface, and Change the Water Uptake Properties and Particle
Morphology
TEM Images of CaCO3 Particles
CaCO3
0.5 
HNO3
Reacted
CaCO3
Goodman et al.,
JGR, 105:29053,
2000
STEM on-line TUV overview
TUV TOP
80km
Overtop O3 =
O3 (Dobson) below STEM top height
EP/TOMS Total Ozone (Dobson)
STEM TOP
15km
Ice cloud
Output:
30 kinds of
J-values
for SAPRC99
mechanism
Water cloud
Inputted from
STEM 3-D
field
Surface
reflection
Dust
Black Carbon
Organic Carbon
Sulfate
Other PM2.5 and Other PM10
absorption by
gas-phase species
O3, SO2 and NO2
Sea Salt
HO2
NO3
N2O5
H2O
HO
O2
HO
RO
O3
HO2
RO2
O3 NO
2
NO
hn
O2
HNO3
hn
HO2
Impact of Aerosols on the
Photochemical Oxidant
Cycle Through Photolysis
Rates
Emission
hn
CH3COO2NO2 Season
HO
CH3COO2
Winter
Spring
Aerosol
DSulfate
impact on O3 %
\
+
18.9
-8.6
Mean
+
-
Mean
Summer
+
-
Mean
Mineral Optical Depth
Fall
+
-
Mean
1.3
13.1
-3.7
1.5
13.7
-4.0
\
15.5
-6.1
DSoot DMineral
%
%
\ 3
\
48.6 13.2
-25.8
-5.8
\
\
24.4
9.7
-11.1
-3.2
\
\
8.3
25.4
-12.9
-3.0
\
\
27.3
9.2
-13.5
-3.8
DTSP
%
\
58.7
-33.0
\
36.8
-16.8
\
37.6
-19.1
\
40.3
-20.6
NOx
NMHC
O3
HOx
%Change NO2 Photolysis
Ozone variations (%) due to dust
UVB
What is the Importance of Heterogeneous Chemistry on
Mineral Aerosol Surfaces in the Troposphere?
Answer Requires:
• Knowing what chemistry occurs on/in the aerosol.
• Quantifying mineral surfaces in space and time.
• Assessing how mineral aerosols age; and how surfaces
activate/deactivate, take on water, etc.
• Quantifying aerosol /radiation interactions.
• Resolving chemical composition as a function of size.
Urban Environments in Asia
 4%/yr urban growth rate in
Asia-Pacific region
 23 megacities in 1995 (17 in
developing countries) to 36 in
2025 (23 in Asia)
 Asia presently has ~1 billion
urban dwellers, projected to
grow to ~3 billion in 2025
 10 Asian Megacities will
account for ~40% of GNP in
2025
 Each 1 million urban
inhabitants emit average of
25,000 tons of CO2 every day
(six times global per capita
average)
 Indoor and Outdoor air
pollution pose severe human
health concerns
Percentage of Sulfur Emissions by
Sector & Fuels for year 2000
100%
100%
80%
80%
OTHER
Others
Gas
60%
PP
60%
TRAN
Fuel Oil
40%
Biofuel
DOM
40%
IND
Coal
Se
ou
l
Ba
ng
ko
k
CON
Be
iji n
g
Sh
an
gh
ai
C
ho
ng
qi
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M
um
ba
i
Ja
ka
rta
D
D
ha
ka
0%
Se
ou
l
Ba
ng
ko
k
0%
Be
iji n
g
Sh
an
gh
ai
C
ho
ng
qi
ng
M
um
ba
i
Ja
ka
rta
20%
ha
ka
20%
% Contribution of Megacities to Total Sulfur Deposition
50
40
60
30
50
20
40
10
30
20
0
10
-10
5
-20
60
70
80
90
100
110
120
130
140
150
1200
800
1975
1000
800
600
(b)
1980
700
1990
600
1995
500
2000
2010
2010maxf
2020
2020maxf
400
400
300
200
200
100
Figure 2. Comparison of SO2 Emissions from the Megacities of Asia, ktons/year
(a) For year 1975, 1980, 1990, 1995 and 2000
(b) For year 2010 and 2020 from RAINS-Asia 7.52
Ba
ng
ko
k
Se
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l
M
um
ba
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Ja
ka
rta
ng
Sh
an
gh
ai
C
ho
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qi
ng
Be
i ji
ha
ka
D
Ba
ng
ko
k
Se
ou
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M
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ba
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Ja
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rta
Sh
an
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C
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qi
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0
Be
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D
ha
ka
0
Integrated Urban AQM
32o
Shanghai
East China
Sea
Shanghai Province
30o36’
120o36’
122o
 Forward looking policies which
anticipate growth in environmental
growth and/or retrofitting are most
cost-effective.
 Policy trajectories include
(example): 1995 - distant siting
(50 km to 75km); 2000 - ESP, coal
washing; 2010 - 2050 - fabric
filters and low-NOx burners.
 IGCC technology for new power
plants and relocation of major
industrial estates and power plants
to outside the city limits.
Health Benefits due to Sulfur and PM Control
in Shanghai
Scenario ==>
C1
Industrial
14
6
9
12
13
C2
Power Sector
41
13
3
4
4
Scenario ==>
C1
1771
1106
60752
30603
27433
C2
2789
1740
95619
48166
43177
94
395
106 - 887
168 - 1, 396
265
1.1 - 9.4
419
0.4 - 3. 5
% Emission Reduction
Sulfur
NOx
TSP
PM10
PM2.5
Total # of Deaths Avoided
Total # of Chronic Bronchitis Cases Avoided
Total # of Hospital Visits Avoided
Total # of Emergency Hospital Visits Avoided
Total # of Hospital Admissions Avoided
Total Control Costs (US $ in millions)
Total Benefits Due to Human Impacts Avoided (in
millions US $)
Median
Health Benefit to Scenario Cost Ratio
Ambient Air Quality Curve in Shanghai
mg/m3
0. 35
0. 3
0. 25
0. 2
0. 15
TSP
0. 1
NOx
0. 05
SO2
0
1991
1992
1993
1994
1995
1996
1997
1998
1999
Concentration Change of Major Air Pollutants in Urban
Area of Shanghai from 1991 to 1999
Air Pollution and Climate Issues are Intimately Linked
China
Emissions
in 20001 (Tg)
D in
China’s
emissions
(2000 –
1995)
(Tg)
Total
global
fossil fuel
emission
ca~1995
(Tg)
Change in
China’s
emissions as
% of
global
total
Temp.
Response
function
DT/DEmissions
(K/Tg) 2,4
Estimated
Change in
global
temperatures
due to changes in
China’s emissions
between 1995 and 2000
(K) 3,4
anthropogenic
fuel combustion
(%)
SO2
20.8
-4.95
134
-3.7%
-8.2 10-3
+0.04
BC
0.91
-0.43
5.1
-8.4%
6.5 10-2
-0.026
CO2
3,218
-109
29,700
-0.037%
3.0 10-5
-0.003
CH4
33.4
+1.16
360
+0.32%
7.5 10-4
+0.001
Net change:
S = +0.012
Urban Air
Pollution
Control
Policies and
Technical
Options
Shanghai
Bombay
Urban Air
Quality
Management
• Megacities feel the change first.
• Health impacts as a primary measure, urban centers
will react to policy measures faster than a
province or a region.
• Important challenge is how to integrate climate and
urban air quality in a manner that enables the
evaluation of complex policies.