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

ium

Bela

rus

Mac

edon

iaB

ulga

ria UK

Slov

enia

Rus

sia

Swed

enC

zech

Rep

.N

ethe

rland

sB

osni

a&H

erz.

Cro

atia

Finl

and

Ger

man

yH

unga

ryIta

lyAl

bani

aS

witz

erla

ndS

lova

kia

Fran

ceYu

gosl

avia

Spa

inAu

stria

Rom

ania

Gre

ece

Portu

gal

Pola

ndC

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enm

ark

Esto

nia

Mon

aco

Icel

and

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tvia

Lith

uani

aLu

xem

bour

gM

alta

Nor

way

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

enC

zech

Rep

.N

ethe

rland

sBo

snia

&Her

z.C

roat

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

iaIc

elan

dIre

land

Latv

iaLi

thua

nia

Luxe

mbo

urg

Mal

taM

onac

oN

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