Presentation Slides for

Chapter 11, Part 1of

Fundamentals of Atmospheric Modeling 2nd Edition

Mark Z. JacobsonDepartment of Civil & Environmental Engineering

Stanford UniversityStanford, CA 94305-4020jacobson@stanford.edu

March 21, 2005

Types of GasesInorganic gases

Contain O, N, S, Cl, Br, and maybe H or C, but not both

Nitric oxide --Organic gases

Contain both H and C, but may also contain other atoms

Carbon dioxide --

Formaldehyde --

Acetone --

Peroxyacetylnitrate --

N O O C O

H C

O

H

H C

H

C

H

O

C

H

H

H

C C

O

O

H

H

H

O

N

O

O

HydrocarbonsOrganic gases that contain only hydrogen and carbon

Propane --

Alkanes - Carbons bonded by a single bond

Cyclobutane --

Ethene (ethylene) --

Cycloalkanes - A ring of alkanes

Alkenes - Carbons bonded by a double bond

H C

H

C

H

H

C

H

H

H

H

H2

C

H2

C CH2

CH2

C C

H

H

H

H

Hydrocarbons

Toluene --

Aromatics - Carbons that form a benzene ring

Isoprene --

Terpenes - Biogenic hydrocarbons

CH3

H

C C

H2

CCH

2

CH3

DefinitionsNon-methane hydrocarbons (NMHC)

Hydrocarbons, except for methane

Oxygenated hydrocarbonsHydrocarbons with oxygenated functional groups, such as aldehydes, ketones, alcohols, acids, and nitrates, added to them

Reactive organic gas (ROG)The sum of oxygenated and NMHC

Total organic gas (TOG)The sum of ROG and methane

Photostationary State Relationship(11.1)

(11.2)

(11.3)

NO + O3

NO2

+ O2

NO2

+ h ν NO + O λ < 420 νm

O + O2

+ M O3

+ M

d NO2[ ]dt =k1 NO[ ] O3[ ]−J NO2[ ]

O3[ ]=J NO2[ ]k1 NO[ ]

Time rate of change of nitrogen dioxide (11.4)

Steady state --> photostationary state relationship (11.5)

Photostationary State RelationshipExample 11.1:Estimate ozone mixing ratio when

pa = 1013 hPa T = 298 KNO = 5 pptv NO2 = 10 pptvk1 = 1.8x10-14 cm3 molec.-1 s-1 J = 0.01 s-1

Solution:[O3] = 1.1x1012 molec. cm-3

Nd = 2.46 x 1019 molec. cm-3

O3 = 44.7 ppbv

Other Reactions Affecting OzonePhotodissociation of ozone (11.6)

(11.7)

Conversion of excited to ground-state atomic oxygen (11.8)

O3

+ h νO

2 + O(

1

D ) λ < 310 νm

O3

+ h ν O2

+ O λ > 310 νm

O(1

D ) O

M

Hydroxyl Radical SourcesMajor (11.9)

Minor (11.10-13)

O(1

D ) + H2

O 2OH

HONO + h ν OH + NO λ < 400 νm

HNO3

+ h ν OH + NO2

λ < 335 νm

H2

O2

+ h ν 2OH λ < 355 νm

HO2

NO2

+ h ν

HO2

+ NO2

OH + NO3

λ < 330 νm

λ < 330 νm

Scavenging by Hydroxyl Radical(11.14-17)

OH + O3

HO2

+ O2

OH + H2

H2

O + H

OH + HO2

H2

O + O2

OH + H2

O2

HO2

+ H2

O

Scavenging by Hydroxyl Radical(11.19-23)

M

OH + NO2

HNO3

OH + SO2

HSO3

M

OH + CO H + CO2

OH + CH4

H2

O + CH3

Hydroperoxy Radical Production

(11.27)

(11.28)

M

H + O2

HO2

HO2

NO2

HO2

+ NO2

M

Hydroperoxy Radical LossHyrdoxyl radical reactions in presence of NO (11.29)

(11.30)

(11.31)

(NO > 10 pptv)

(NO 3-10 pptv)

(NO < 3 pptv)

M

H O2

+ NO OH + NO2

HO2

+ NO2

HO2

NO2

HO2 +

O3

OH + 2O2

HO2

+ HO2

H2

O2

+ O2

Nighttime Nitrogen ChemistryProduction of nitrate radical (11.32)

Dinitrogen pentoxide formation / decomposition (11.33)

NO2

+ O3

NO3

+ O2

M

NO2

+ NO3

N2

O5

Nighttime Nitrogen ChemistryDinitrogen pentoxide reaction, photolysis (11.34)

Nitrate radical photolysis (lifetime of minutes) (11.35)

(11.36)

N2

O5

+ H2

O(aq) 2HNO3

(aq)

N2

O5

+ h ν NO2

+ NO3

λ < 385 νm

NO3

+ h ν

NO2

+ O

NO + O2

410 νm < λ < 670 νm

590 νm < λ < 630 νm

Ozone From Carbon Monoxide

(11.37-41) CO + OH CO2

+ H

M

H + O2

HO2

NO + HO2

NO2

+ OH

NO2

+ h ν NO + O λ < 420 νm

O + O2

+ M O3

+ M

Ozone Formation From Methane(11.42)

(11.43)

CH4

+ OH CH3

+ H2

O

+ O2

, M

C

H

H

H

Methyl

radical

C

H

H

H

O

O

Methylperoxy

radical

H

C O

H

H

Methoxy

radical

O2

NO2

+ NO

+ HO2

H C

H

O

H

O H

Methyl

hydroperoxide

H C

O

H

Formaldehyde

+ O2

HO2

(11.40)

(11.41)

NO2

+ h ν NO + O λ < 420 νm

O + O2

+ M O3

+ M

Methyl Hydroperoxide Decomposition(11.44)

H C

O

H

Formaldehyde

+ O2

HO2

H

C O

HOH

Methoxy

radical

H C

H

O

H

O H

+ h ν

C

H

H

H

O

O

Methyλperoxy

radiaλ

Methyλ

hydroperoxide

λ < 360 νm

H

+ OH

H2

O

Ethane Oxidation

Methylperoxy radical production and loss (11.45)

Ethane

H C

H

C

H

H

H

H C

H

C

H

H

H

Ethyl radical

H

H C

H

C

H

O

H

H

O

Ethylperoxy radical

+ O2

, M

+ OH

H2

O

Ethane Oxidation(11.46)

H C

H

C

H

O

H

H

O

Ethylperoxy radical

H C

H

C

H

H

H

Ethoxy radical

O

NO2

+ NO

Acetaldehyde

H C

H

C

H

O

H

+ O2

HO2

+ NO2

M

H C

H

C

H

H

O

H

Ethylperoxynitric acid

O

N

O

O

Propane OxidationMethylperoxy radical production and loss (11.47)

+ O2

, M

H C

H

C

H

H

C

H

H

H H C

H

C

H

H

C

H

H

Propane n -Propyl radical

H H

H C

H

C

H

H

C

H

H

O

H

n -Propylperoxy radical

O

+ OH

H2

O

NO2

+ NO

H C

H

C

H

H

H

n -Propoxy radical

C

H

H

O H C

H

C

H

O

C

H

H

H

Acetone

+ O2

HO2

Formaldehyde/Acetaldehyde PhotolysisFormaldehyde (11.48)

Acetaldehyde (11.49)

Eormyl radical (11.50)

H C

O

H

Formaldehyde

+ h ν

+ H

Formyλ

radiaλ

CO + H2

λ < 334 νm

λ < 370 νm

C

HO

+ h ν

C

H

H

H

CH C

H

C

H

Aetaλdehyde Methyλ radiaλ Formyλ radiaλ

+

O

H

O

H

λ < 325 νm

Formyl

radical

C

O

H

CO

+ O2

HO2

Formaldehyde/Acetaldehyde ReactionFormaldehyde (11.51)

Acetaldehyde (11.52)

CH C

Formaldehyde Formyl radical

O

H

O

H

+ OH

H2

O

C C

O

H

H

H

H

Acetaldehyde Acetyl radical

C C

OH

H

H

Peroxyacetyl

radical

C C

O

O

H

H

H

O

+ OH

H2

O

+ O2

, M

Formaldehyde/Acetaldehyde ReactionPAN formation (11.53)

Peroxyacetyl

radical

C C

O

O

H

H

H

O

Acetyloxy radical

C C

O

O

H

H

H

Peroxyacetyl nitrate

C C

O

O

H

H

H

O

N

O

O

NO2

+ NO

+ NO2

, M

Acetone Photolysis(11.55)

H C

H

C

H

O

C

H

H

H

Acetone

+ h νC

H

H

H

Methyλ radiaλ

+

Aetyλ radiaλ

C C

OH

H

H

Sulfur PhotochemistryBiogenic sulfur

H2S -- hydrogen sulfideCH3SH -- methyl sulfideCH3SCH3 -- dimethyl sulfide (DMS)CH3SSCH3 -- methyl disulfide

Volcanic sulfurCS2 -- carbon disulfideOCS -- carbonyl sulfideSO2 -- sulfur dioxideH2S -- hydrogen sulfide

Sulfur PhotochemistrySulfuric acid formation from sulfur dioxide (11.74)

S

OO

O

S

HO O

O

S

O O

+ OH, M+ H

2O

Sulfur

dioxide

Bisulfite Sulfur

trioxide

Sulfuric

acid

S

O

OH

O OH

+ O2

HO2

DMS Abstraction PathwaySulfur dioxide production from dimethyl sulfide (DMS) (11.56)

+ O2

H C

H

S

H

C

H

H

H H C

H

S

H

C

H

H

H C

H

S

H

C

H

H

O

O

Dimethyl sulfide (DMS) DMS radical DMS peroxy radical

+ OH

H2

O

H C

H

S

H

C

H

H

O H C

H

S

H

+

H C

O

H

DMS oxy radical Methanethiolate

radical

Formaldehyde

M

NO2

+ NO

DMS Abstraction PathwayMethanethiolate radical reaction (11.57)

H C

H

S

H

H C

H

S

H

O

O

Methanethiolate

radical

Excited methanethiolate

peroxy radical

*

H C

H

S

H

O

O

Methanethiolate oxy

radical

Methanethiolate

peroxy radical

M

H C

H

S

H

O

+ O2

, M

NO2

+ NO

DMS Abstraction PathwayMethanethiolate oxy radical reaction (11.58)

H C

H

H

Methyl

radical

H C

H

S

H

O

+

H C

H

S

H

O

O

S O

Sulfur monoxide

Methanethiolate

peroxy radical

Methanethiolate oxy

radical

M

+ O3

O2

DMS Abstraction PathwaySulfur dioxide production from sulfur oxide (11.59)

Sulfur dioxide production from sulfur oxide (11.60)

S

OO

OSulfur

monoxide

S O

Sulfur

dioxide

+ O2

S

OO

H C

H

H

+H C

H

S

H

O

O

Methyl radical Sulfur dioxideMethanethiolate

peroxy radical

M

DMS Addition PathwayMethanethiolate oxy radical reaction (11.61)

H C

H

S

H

C

H

H

H

+ OH

Dimethyl sulfide (DMS)

H C

H

S

H

C

H

H

H

OH

H C

H

H

H C

H

S

H

O

H

O

S C

O

C

H

H

H

H

H

H

+

Dimethyl sulfone (DMSO2

)

Methanesulfenic

acid

Methyl

radical

DMS-OH adduct

M

+ OH, 2O2

2 HO2

DMS Addition PathwayMethanesulfenic acid oxidation (11.62)

Methanethiolate oxy

radical

H C

H

S

H

O

H

Methanesulfenic

acid

H C

H

S

H

O

+ OH

H2

O

DMDS ReactionOH addition (11.63)

Photolysis (11.64)

H C

H

S

H

S C

H

H

H H C

H

S

H

O

H

H C

H

S

H

+

Dimethyl disulfide (DMDS) Methanesulfenic

acid

Methanethiolate

radical

+ OH

H C

H

S

H

S C

H

H

H H C

H

S

H

2

Dimethyl disulfide (DMDS) Methanethiolate

radical

+ h ν

Biogenic SulfurHydrogen sulfide oxidation (11.65)

Hydrogen sulfide radical reaction (11.66)

Sulfur dioxide production from sulfur oxide (11.59)

S

HH

S

H

Hydrogen

sulfide

Hydrogen

sulfide radical

+ OH

H2

O

+ O2

S

H

OH

Hydrogen

sulfide radical

Sulfur

monoxide

S O

S

OO

OSulfur

monoxide

S O

Sulfur

dioxide

+ O2

Volcanic SulfurSulfur monoxide production from carbonyl sulfide (11.68)

(11.69)

(11.70)

+ OHO C S

S

H

Hydrogen sulfide

radical

+ CO2

Carbonyl

sulfide

Carbonyl

sulfide

O C S +

Carbon

monoxide

Atomic

sulfur

+ h ν λ < 260 νmCO S

O

+ O2

Sulfur

monoxide

S O

Atomic

sulfur

S

Volcanic SulfurSulfur oxide production from carbon disulfide (11.71)

(11.72)

(11.73)

+ OHS C S

S

H

O C S+

Carbon

disulfide

Hydrogen sulfide

radical

Carbonyl

sulfide

S C S +C S

Carbon

disulfide

Carbon

monosulfide

Atomic

sulfur

+ h ν S λ < 340 νm

+ O2C S

Carbon

monosulfide

+ OO C S

Carbonyl

sulfide

Urban PhotochemistryOzone production in smog (11.75-8)

NO + ROG * NO2

+ ROG **

NO + O3

NO2

+ O2

NO2

+ h ν NO + O λ < 420 νm

O + O2

+ M O3

+ M

0 0.5 1 1.5 2

0

0.05

0.1

0.15

0.2

0.25

ROG (ppmC)

NO

x

(g) (ppmv)

0.4

0.32

0.24

0.16

0.08 = O

3

(g), ppmv

Ozone Isopleth

Fig. 11.1Contours are ozone (ppmv)

NO

x (pp

mv)

0.24

0.08

0.32

0.16

Sea Breeze

Fig. 11.2

0

1

2

3

4

5

6

7

0 6 12 18 24 30 36 42 48 54 60 66 72

Wind speed (m s

-1

)

Hour of day

Day 1 Day 2

Day 3

Win

d sp

eed

(m s-1

)

Source/Receptor Regions in Los Angeles

0

0.1

0.2

0.3

0 6 12 18 24

Volume mixing ratio (ppmv)

Hour of day

O

3

NO

2NO

Central Los Angeles

August 28, 1987

Vol

ume

mix

ing

ratio

(ppm

v)

Fig. 11.2

0

0.1

0.2

0.3

0 6 12 18 7224

Volume mixing ratio (ppmv)

Hour of day

O

3

NO

2

NO

San Bernardino

August 28, 1987

Vol

ume

mix

ing

ratio

(ppm

v)

Daily Los Angeles Emission (1987)

Table 11.2

Gas Emission (tons/day) Percent of totalCarbon monoxide 9796 69.3

Nitric oxide 754Nitrogen dioxide 129Nitrous acid 6.5

Total NOx+HONO 889.5 6.3Sulfur dioxide 109Sulfur trioxide 4.5

Total SOx(g) 113.5 0.8Alkanes 1399Alkenes 313Aldehydes 108Ketones 29Alcohols 33Aromatics 500Hemiterpenes 47

Total ROGs 2429 27.2Methane 904 6.4

Total emission 14,132 100

Percent Emission by SourceNitric oxide from combustion (11.79)

N N O O N O+ 2+ heat

Table 11.4

Source Category CO(g) NOx(g) SOx(g) ROG Stationary 2 24 38 50Mobile 98 76 62 50Total 100 100 100 100

Organic Gases Emitted in Greatest Abundance in Los Angeles (1987)

Table 11.3

1. Methane2. Toluene3. Pentane4. Butane5. Ethane6. Ethylene7. Octane8. Xylene

9. Heptane10. Propylene11. Chloroethylene12. Acetylene13. Hexane14. Propane15. Benzene

Most Important Gases in Smog in Terms of Ozone Reactivity and Abundance

Table 11.6

1. m- and p-Xylene2. Ethene3. Acetaldehyde4. Toluene5. Formaldehyde6. i-Penane7. Propene8. o-Xylene9. Butane10. Methylcyclopentane

Lifetimes of ROGs Against Loss in Urban Air

Table 11.5

ROG Species Phot. OH HO2 O NO3 O3 n-Butane --- 22 h 1000 y 18 y 29 d 650 ytrans-2-butene --- 52 m 4 y 6.3 d 4 m 17 mAcetylene --- 3 d --- 2.5 y --- 200 dFormaldehyde 7 h 6 h 1.8 h 2.5 y 2 d 3200 yAcetone 23 d 9.6 d --- --- --- ---Ethanol --- 19 h --- --- --- ---Toluene --- 9 h --- 6 y 33 d 200 dIsoprene --- 34 m --- 4 d 5 m 4.6 h

OH Sources in Polluted AirEarly morning source (11.80)

Mid-morning source (11.81)

(11.82)

(11.83)

λ < 400 nmOH + NOHONO + h ν

HCHO + h ν λ < 334 νmH + HCO

M

H + O2

HO2

HCO + O2

HO2

+ CO

(11.84)NO + HO

2NO

2 + OH

Hydroxyl Rad. Sources in Polluted Air

Afternoon source (11.88)

(11.86)

O3

+ h ν O2

+ O(1

D ) λ < 310 νm

O(1

D ) + H2

O 2 OH

Alkene Reaction With Hydroxyl Radical

Ethene oxidation (11.87)

C C

H

H

H

H

Ethene

C C

H

H

H

H

Ethanyl radical

OH

C C

H

H

H

H

Ethanolperoxy

radical

OH

O

O

C C

H

H

H

H

Ethanoloxy

radical

OH

O

+ OH, M + O2

, M

NO2

+ NO

Alkene Reaction With Hydroxyl Radical

Ethanoloxy radical oxidation (11.88)

Formaldehyde

C O

H

H

C C

H

H

H

H

Ethanoloxy

radical

OH

O

C C

H

H

O

H

OH

Glycol aldehyde

72% 2

28%

+ O2

HO2