Atmospheric transport modeling
Local dispersion modeling – example from the EU EMECAP project
Regional dispersion modeling – example from the UN EMEP project
Global dispersion modeling – example from the Hg modeling
N:\adm\arkiv\overhead\2006\CEE\Yale-6.ppt 1
The chemistry model
Results
Ventilated box model
Wind dependent emission
GEM and RGM dispersion
Deposition fields
Dispersion
and chemistry modelling of Mercury
Chemistry
220 HgClClHg
HgClClHg 0
2HgClClHgCl ClHgClClHgCl 22
MClHgMHgCl 0
223 ONONOO
)(12 DONONO
h
MOMODO 321 )(
Mercury/chlorine chemistry
Chlorine/NOx /O3 chemistryClCl
h22
23 OClOOCl
2NOClNOClO MClNOMNOClO 32
Box model calculations, input dataBohus Rosignano Tarnow
GEM concentration(g/m3) 11.2 35, 125(1)
RGM concentration(g/m3) 0.086 10
Cl2 concentrations (g/m3) 800 392(1)
Volume (m3) 27 900 30 000 73 440
Ventilation (m3/hr) 620 000 220 000
GEM emission (kg/yr) 62(2) , 50(3) 72.1 x U (3) 68(2), 243(3)
RGM emission (kg/yr) 0.5(2) 19(2)
Cl2 emission (kg/yr) 4300 5000 x U (4) 738, 1100(4)
(1) Concentrations calculated from emission and ventilation data(2) Emissions calculated from concentration and ventilation data(3) Emissions calculated from Lidar measurements(4) Chlorine emissions calculated from Chlorine production relative to Bohus plant.
0021
VolumenVentilatioRGMHgClk
dtdRGM
Observed RGMconcentration
(g/m3)
Caculated RGMconcentration
(g/m3)
Bohus 0.086 0.070
Tarnow 10 0.79
Simplified box model calculations
Tested for sensitivity to
1. Radiation levels
2. Ozone levels
3. Thermal disassociation rate for HgCl
4. Reaction rate for HgCl + Cl2
Complete box model calculations
Complete box model results for Bohus% of maximum radiation
Hg(g/m3)
Cl2(g/m3)
O3
g/m3
Reaction ratek5 (s
-1)k4 (cm-3mol-1s-1)
HgCl2(RGM)(ng/m3)
HgCl
(ng/m3)
Cl
(ng/m3)Radiation (k4 =0)
0 11.2 800 100 1.010 –1 (k5 ) 70 0 01.5 11.2 800 100 1.010 –1 (k5 ) 84 95 3.35 11.2 800 100 1.010 –1 (k5 ) 165 259 9.110 11.2 800 100 1.010 –1 (k5 ) 525 564 19.1
Ozone (k4 =0)5 11.2 800 150 1.010 –1 (k5 ) 110 169 5.85 11.2 800 100 1.010 –1 (k5 ) 165 259 9.15 11.2 800 50 1.010 –1 (k5 ) 445 520 19.3
Thermal disassociation of HgCl (k4 =0)5 11.2 800 100 5.010 –1 (k5 ) 91.5 52 9.25 11.2 800 100 1.010 –1 (k5 ) 165 259 9.15 11.2 800 100 2.010 –2 (k5 ) 410 990 8.9
Reaction rate for HgCl + Cl2 (k5 =1.010 –1)5 11.2 800 100 3.010 –17 (k4 ) 174 259 9.15 11.2 800 100 3.010 –16 (k4 ) 282 258 9.25 11.2 800 100 3.010 –15 (k4 ) 1130 221 9.25 11.2 800 100 3.010 –13 (k4 ) 5710 11.5 8.2
Conclusion of Box model calculations
• The reaction Hg + Cl2 HgCl2 is sufficient to produce the observed RGM levels at Bohus but not at Tarnow
• RGM levels are sensitive to:
• Radiation
• Ozone levels
• Several unknown reaction rates
• Without more data and improved chemical knowledge no firm conclusions can be drawn
Comparison with TAPM results, TGM
0
5
10
15
20
25
30
35
40
1 2 3 4 5 6 7 8 9Station number
Mea
n co
ncen
tratio
n (n
g/m
3)
OBSERVEDTAPMEPISODE
Dispersion results using EPISODE
Wind speed dependence of emissions, TGM
0
10
20
30
40
50
60
70
80
90
100
17 18 19 20 21 22 23 24 25 26 27 28 29
Day of month in June
Con
cent
ratio
n (n
g/m
3)
Observed S1EPISODE+ without wdeEPISODE+ with wde
Dispersion results using EPISODE
Effect of wind dependent emissions, chemistry and deposition on GEM
0
5
10
15
20
25
30
35
40
1 2 3 4 5 6 7 8 9Station number
Mea
n co
ncen
tratio
n (n
g/m
3)
OBSERVED (GEM)EPISODEWind dependent emissionsWith ChemistryWith chemistry and deposition
Dispersion results using EPISODE
Dry deposition velocities for Mercury not well defined
GEM
0.05 cm/s
RGM
2.0 cm/s
Though RGM concentrations are low, its deposition is high and can be as, or more, important than GEM deposition
Deposition of Mercury
Effect of chemistry and deposition on RGM
0
0.05
0.1
0.15
0.2
0.25
1 7Station number
Mea
n co
ncen
tratio
n (n
g/m
3)
OBSERVED (RGM)No chemistry, no deposition (2% GEM emissions) With Chemistry, no deposition (2% GEM emissions) With chemistry and deposition (2% emissions) With chemistry and deposition (20% GEM emissions)
Dispersion results using EPISODE
0
10
20
30
40
50
60
70
80
90
100
−6000 −4000 −2000 0 2000 4000 6000−6000
−4000
−2000
0
2000
4000
6000Average Mercury deposition through RGM (ng/m2/hr) Rosignano. June, 2002
X (m)
Y (
m)
. 1
. 2 . 3
. 4
. 5
. 6
. 7. 8
. 9
0
10
20
30
40
50
60
70
80
90
100
−6000 −4000 −2000 0 2000 4000 6000−6000
−4000
−2000
0
2000
4000
6000Average Mercury deposition through GEM (ng/m2/hr) Rosignano. June, 2002
X (m)
Y (
m)
. 1
. 2 . 3
. 4
. 5
. 6
. 7. 8
. 9
GEM deposition field
Total deposition = 0.51 g/hr2.5% of GEM emissions
RGM deposition field(2% of GEM)
Total deposition = 0.11 g/hr53% of RGM emissions
Deposition results using EPISODE
Compound Emissions of Hg(g/hr)
Total deposition of Hg in model domain (g/hr)
Percentage of emissionsDeposited (%)
Percentage of totalDeposition (%)
GEM (Hg0) 20 0.51 2.5 82 (2 %)32 (20 %)
RGM (HgCl2 ) (2 %) 0.21 0.11 53 18
RGM (HgCl2 ) (20 %) 2.1 1.1 53 68
TOTAL Hg (2 %) 20.2 0.62 3.1
TOTAL Hg (20 %) 22.1 1.61 7.2
Summary of total deposition of elemental Mercury from GEM and RGM in the model domain (12.5 x 12.5 km). The percentage in brackets indicates the % of RGM emitted in relation to GEM
Summary of deposition results
Wind speed dependence of emissions reduces night time concentrations significantly
Chemistry not important for RGM concentrations after emission from the plant
Deposition rates for RGM not well known, assumed high
Best results for RGM come from low emissions and low deposition or high emissions and high deposition
From 3% to 7% of total Hg emissions are dry deposited in the surrounding 150 km2 at Rosignano
Conclusions of chemistry and deposition studies
Coverage: EMEP region
Resolution: (50km×50km)
Vertical structure:9 terrain-following layers up to 12 km
МСЦ-В
MSC-E
Computation domain
Anthropogenic emissions in 2000
Emissions from chlor- alkali industry
МСЦ-В
MSC-E
Mercury emissions
Natural emission
МСЦ-В
MSC-E
Mercury emissions
Spatial distribution of mercury reemission from soil in Europe
Total gaseous mercury in ambient air in 2000
Contribution of chlor- alkali emissions
МСЦ-В
MSC-E
Mercury concentration in air
Annual mercury deposition in 2000
Contribution of chlor- alkali emissions
МСЦ-В
MSC-E
Mercury depositions
Relative contribution to mercury air concentration
Relative contribution to mercury deposition
МСЦ-В
MSC-E
Contribution of chlor-alkali industry
Ukr
aine
Mol
dova
Belg
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Bela
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Mac
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iaB
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Slov
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and
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Fran
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gosl
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Rom
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alta
Nor
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05
10152025303540
Con
tribu
tion,
%
Relative contribution of chlor-alkali plants to totalanthropogenic emissions of mercury in Europeancountries in 2000
Ukr
aine
Mol
dova
Bel
gium
Bela
rus
Mac
edon
iaBu
lgar
ia UK
Slov
enia
Rus
sia
Swed
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zech
Rep
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ethe
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sBo
snia
&Her
z.C
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iaFi
nlan
dG
erm
any
Hun
gary
Italy
Alb
ania
Sw
itzer
land
Slo
vaki
aFr
ance
Yugo
slav
iaSp
ain
Aus
tria
Rom
ania
Gre
ece
Portu
gal
Pol
and
Cyp
rus
Den
mar
kE
ston
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land
Latv
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thua
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taM
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orw
ay
05
101520
406080
100 Maximum Average
Con
tribu
tion,
%
Relative contribution of chlor-alkali plants to depositionof anthropogenic mercury to European countries in 2000
Mercury deposition to the ArcticInfluence of MDE
МСЦ-В
MSC-E
without MDPwithout MDP with MDPwith MDP
Contribution of MDP Contribution of MDP ––50 t/y (~20%)50 t/y (~20%)
Mercury deposition in the NH
МСЦ-В
MSC-E
Total annual mercury deposition densityTotal annual mercury deposition density