Gerhard Lammel: “Trends and Advances in Atmospheric and
Environmental Chemistry"
Cloud chemistry: Ozone, acidity formation, dimethyl sulphide
Atmospheric aerosol, its composition, surface and bulk particle reactions
- humidity/supersaturation S (:=rh-1) is altitude (above cloud base)-dependent
- 15% of the volume of the troposphere filled with clouds
- liquid water content L = 0.1-2×10-6 Vwater/Vair = 0.1-2 g/m³
= (0.1-2)×10-3 L/m³ < 10% of total water content (10-40 g/m³!) only  10% of clouds will rain
out, while 90% will recycle aerosol particles
- lifetime of clouds hours-days, of cloud droplets (D=5-50 µm) minutes
- aqueous composition: dissolved (ci  10-6 - 10-3 M) + eventually non-dissolved constituents,
droplet-size dependent, ci(D)
Cloudwater - introduction, significance
Terminology:
• Hydrometeors = cloud droplets + ice particles + rain
droplets + snow flakes + graupel + ...
• Wet deposition = rain + snow fall + rime
• Wash-out = below-cloud scavenging + in-cloud scavenging
of both gases and particles
• in-cloud scavenging of gases = dissolution
• Occult deposition = droplet deposition from clouds, fogs
else than rain or snow fall
some units:
• 1 M = 1 mol/L
• pH 7 ↔ cH3O+ = 10-7 M
(Warneck, 1999)
Henry coefficients
Solubility increases with decreasing temperatures,
e.g. 78, 63 and 53% of O2 at 0°C is soluble at 10, 20 and 30°C, respectively.
Compilation of KH :
• Warneck, Phys. Chem. Chem. Phys. 1 (1999) 5471-5483
• download from Rolf Sander’s webpage, MPI-C
http://www.mpch-mainz.mpg.de/~sander/res/henry.html
...with diluted solutions (ideal behaviour).
The in-cloud scavenged fraction of gaseous molecules is dependent on water
solubility:
i(g) = ni(aqu) / (ni(aqu) + n(g)) = ni(aqu) / [ni(aqu) + piVair/(RgT)] =
= ni(aqu) / [ni(aqu) + Hi ni(aqu)Vair/(RgT nH2O)] =
= [1 + HiMw/(Rg T L)]-1
with: Henry coefficient Hi [at] = pini(aqu)/nH2O = pi xi = pi/(ci/103/Mw),
liquid water content L [g/m³]
gas constant Rg = 8.206×10-5 m3 at/mol/K, Mw[g/mol], 103[cm3/L]
(Warneck, 1986)
Another, more common Henry coefficient:
KH [M at-1] = 102 s/Mwp = (103/Mw) × H2O/H
solubility s(T) [mg/L] = s(T0) × exp[-Hsol/Rg × (1/T-1/T0)]
Sulfuric acid formation in the aqueous phase
Dissolution of gases - thermodynamic equilibrium
... confusing: there are more common so-called ‚Henry coefficients‘:
Air-water partitioning coefficient Kaw [ ] = Mwp/(105 RgTs) = 1/ (103 RgTKH)
Henry coefficient H‘ [Pa m³/mol] = RgTKaw = 10-2/KH[M/at]
Ozone is a source of radicals and H2O2 in cloudwater:
(1a) O3 aqu + OHaqu
 O2
aqu
+ HO2
.
aqu
(1b) + HO2
.
aqu  2 O2 aqu + OH.
aqu
(1c) + OH.
aqu  O2 aqu + HO2
.
aqu
(2a) HO2
.
aqu + OH.
aqu  O2 aqu + H2O
(2b) + HO2
.
aqu O2 aqu + H2O2
(3b) H2O2 + h  2 OH.
aqu
Ozone reactions
Tropospheric ozone and clouds
Differences in solubility and
chemical reactivity in the
aqueous phase result in changed
(overall) chemistry of the
atmosphere.
pH dependencies, e.g. O3 sink A6
(O3 + O2
- + H2O  )
O3, OH, NOx overestimated when
clouds are neglected
(Lelieveld & Crutzen, 1990)
Solubility of CO2 (g) ⇋ CO2 aqu + 20 kJ/mol
(1) KH = cCO2 aqu / pCO2 = 3.4×10-7 mol/L/Pa (298 K)
CO2 aqu + H2O ⇋ HCO3
- + H3O+
(2) KA1 = (cHCO3- cH3O+) / cCO2 aqu = 10-6.35
HCO3
- + H2O ⇋ CO3
2- + H3O+
(3) KA2 = (cCO3-- cH3O+) / cHCO3- = 10-10.33
Dissolved
carbon dioxide
Hydrogen
ion
CO2(aq) + H2O(aq) H2CO3(aq) H+ + HCO3
-
Liquid
water
Dissolved
carbonic acid
Bicarbonate
ion
Hydrogen
ion
2H+ + CO3
2-
Carbonate
ion
Dissolved fraction is pH dependent, expressed as the effective Henry coeff. H*:
KH CO2
* = (cCO2 aqu + cHCO3- + cCO3--) / p (mol/L/Pa)
KH
* = KH (1 + KA1 / cH3O+ + KA1KA2 / cH3O+
2)
pH of water in the atmosphere in equilibrium with CO2 (pCO2 = 36 Pa):
(1) in (2): cHCO3- cH3O+ = KA1 KH pCO2
cHCO3- = cH3O+
cH3O+ = (KA1 KH pCO2)0.5
pH = - 0.5 (-pKA1 - log KH - log pCO2)
pH = 0.5 (6.35 - log 3.4×10-7 - log 36) = 5.63
pH scale
Courtesy: Jacobson
during the day: NO2 + OH  HNO3 fast: 9.2×10-12 cm³ molec-1 s-1
(Mollner et al., 2010)
during night: NO2 + NO3 ⇌ N2O5
phase equilibria of N(-III), N(IV), N(V) species:
NH3 ⇌ NH3 aqu.
NO2 ⇌ NO2 aqu
HNO3 ⇌ HNO3 aqu
N2O5 ⇌ N2O5 aqu
dissociation, hydration N(-III), N(V):
NH3 aqu + H2O  NH4
+
aqu + OH-
aqu
HNO3 aqu + H2O  H3O+
aqu + NO3
-
aqu
2 NO2 + 3 H2O  NO2
aqu
+ NO3
aqu
+ 2 H3O+
aqu; slow (Lee & Schwartz, 1981)
N2O5 aqu + 3 H2O  2 H3O+
aqu + 2 NO3
-
aqu
Acidity formation in the troposphere: N
Nitrogen compounds in the aqueous phase
more phase equilibria of N(-III), N(V) species:
HNO2 ⇌ HNO2 aqu KH = 50 M at-1
HNO4 ⇌ HNO4 aqu KH = 1.4×106 M at-1
dissociation, hydration N(-III), N(V):
HNO2 aqu + H2O ⇌ H3O+
aqu + NO2
aqu
KA = 0.6×10-5 M
HNO4 aqu + H2O ⇌ H3O+
aqu + NO4
aqu
KA = 1.0×10-5 M
(Lammel et al., 1990)
HNO4 aqu ⇌ HO2
.
aqu + NO2 aqu KA = 4.6×10-10 M
NO4
aqu
 O2 aqu + NO2
aqu
k = 1.4×10-2 s-1
Crete, 2001-03 (Vrekoussis et al., 2006)
HNO3 production: sources
(1a) NO2 + .OH  HNO3 (day)
(1b) NO2 + NO3
. ⇌ N2O5 (night)
(2b) dissolution + hydration:
N2O5 +3 H2O  2 H3O+
aqu. +2 NO3
-
aqu.
Formation of sulfuric acid in the (A) gas-phase:
(1) SO2 + OH.  HOSO2
.
(2) HOSO2
. + O2  SO3 + HO2
.
(3) SO3 + 2 H2O  H2SO4×H2O
net:
(1-3) SO2 + OH. + O2 + 2 H2O  H2SO4×H2O + HO2
.
Then very fast phase change by nucleation ( 3.1 Aer) and
subsequent condensation
Acids: formation reactions and cloud chemistry
Sulfuric acid formation in the gas-phase
Alkenes react readily with ozone: k  10-10 cm3 molec-1 s-1
(1) CH3CH=CH2 + O3  [primary ozonide]
(2a) [primary ozonide]  CH3CH(OO.)CH2O. 55%
(3a) decomposition:  CH3CH.OO. + HCHO
(3b) + SO2  SO3 k  0.6×10-12 cm³/molec/s (estimate)
(4b) SO3 + 2 H2O  H2SO4×H2O additional gas-phase source for H2SO4!
O
OO
CH3
Chemical mechanism modified, Hohenpeissenberg data set; Boy et al.., 2012
However, only 15% of S(VI) is formed in the gas-phase
globally,
85% is formed (B) in cloud droplets and humid aerosol
particles
S(IV): = SO2 aqu.+ HSO3
- + SO3
2Phase
equilibrium (Henry coeff., physical solubility of SO2):
SO2 ⇋ SO2 aqu. KH (298K):= cSO2/pSO2 = 1.2×10-5 M/Pa
Dissociation equilibria:
SO2 aqu. + 2 H2O ⇋ HSO3
- + H3O+ KA1 (298K)= 1.7×10-2 M
HSO3
.
+ H2O ⇋ SO3
2- + H3O+ KA2 (298K)= 6.5×10-8 M
S(IV) phase equilibrium and reactions
determined by Henry coeff. KH, pH, T
For substances which interact with water to form ions via acid-base dissociation
equilibria KH must be replaced by a modified coefficient KH*:
(‚modified Henry coeff.‘):
KH (298K)*:= cS(IV)/pSO2 = KH (1 + KA1/cH3O+ + KA1KA2/cH3O+²) = f(pH)
S(IV): = SO2 aqu.+ HSO3
- + SO3
2Phase
equilibrium (Henry coeff., physical solubility of SO2),
subsequent dissociation:
SO2 ⇋ SO2 aqu. ⇋ HSO3
- + H3O+ ⇋ SO3
2- + 2 H3O+
Sulfur dissolved bisulfite sulfite
dioxide sulfur
gas dioxide
... and S(VI) phase equilibrium and dissociation
similarly:
S(VI): = H2SO4 aqu. + HSO4
aqu
+ SO4
2-
aqu
Hydrogen
ion
H2SO4(aq) H+ + HSO4
-
Dissolved
sulfuric acid
Bisulfate
ion
Hydrogen
ion
2H+ + SO4
2-
Sulfate
ion
H2SO4(g)
Sulfuric
acid gas
Acid-base dissociation equilibrium
(Warneck, 1999)
Bulk aqueous phase chemistry
Dissociated / undissociated species exist in ratios determined by
acidity (pH) and the dissociation constant, KA. E.g., SO2 aqu.for pH <
-log KA1= 1.7, SO3
2- for pH > -log KA2 = 7.1 and HSO3
- in between.
S(IV) oxidation reactions
(Graedel & Weschler, 1981; Warneck, 1999)
(1) SO3
2aqu
+ HO2
.
aqu  SO4
2aqu
+ OH.
aqu
HO2 or HSO3
(2)
+ OH.
aqu  SO3
- .
aqu + OH aqu
 SO5
- .
aqu   SO4
2-
aqu
(3a) HSO3
aqu
+ O3 aqu  HSO4
aqu
+ H2O k3a = 3.2×105 M-1s-1
(3b) SO3
2aqu
+ O3 aqu  SO4
2aqu
+ H2O k3b = 1.5×109 M-1s-1
(4) HSO3
aqu
+ H2O2 aqu  HSO4
aqu
+ H2O k4 = 4.0×107 cH+ M-1s-1
<Mn+>
(5) 2 HSO3
aqu
+ O2 aqu  2 HSO4
aqu
“autoxidation“ reactions
Oxidations are pH dependent,
because in individual steps of the
reactions of SO2 aqu, HSO3
-
aqu
and SO3
2aqu
(which are
present in pH-dependent fractions
according to KS1, KS2) is H +
aqu
consumed or formed.
for L = VH2O(l)/V = 3×10-6 (Seinfeld, Calvert)
Acidity formation in the troposphere: sulfuric acid
Aciditiy of precipitation and SO2
emissions
• discovery of acid rain 1852 (Smith)
• discovery of acidification of freshwater,
Norway 1920
• effects on fishes, 1970
Tropospheric trace
substances trends: pH, SO2
Annual S wet deposition (NADP) and estimated
total (USEPA) deposition at Huntington Forest in
the central Adirondacks (Driscoll et al., 2016)
SO2 emissions
Reduction 60% 2010 vs. 1990
Rain water pH
Aciditiy of precipitation and SO2
emissions
Tropospheric trace
substances trends: pH, SO2
Rain water pH
Duan et al., 2016
SO2 emissions
Aerosol constituents
McDonald Beach
[nmol/m³]
seasalt-S(VI)/Cl- = 0.051
Sulfuric acid: precursors other than anthropogenic SO2
Terminology:
• NSSS = non-sea salt sulfate
• DMS = dimethylsulfide, CH3SCH3
• MSA = methanesulfonate, CH3SO3
-
(1) CH3SCH3 + OH  CH3SCH2
. + H2O
CH3SCH2
. + O2 + M  CH3SCH2OO. + M
(2) CH3SCH2OO. + NO  CH3SCH2O. + NO2
(3a) CH3SCH2O.  HCHO + CH3S. major
(Gas-phase chemistry)
Dimethylsulfide
Formation of SO2
in the marine
boundary layer:
CH3SCH3   CH3S.
CH3S.  
S(IV)   S(VI)
Formation of SO2
dimethylsulfoxide
dimethyl sulfone
Hypothetical negative
feedback mechanism in the
marine boundary layer:
CH3SCH3 emission
 more clouds
 less radiative flux
 less phytoplankton
 less CH3SCH3 emission
(CLAW hypothesis; Charlson
et al., 1987)
(1) CH3SCH3 + OH  CH3SCH2
. + H2O
CH3SCH2
. + O2 + M  CH3SCH2OO. + M
(2) CH3SCH2OO. + NO  CH3SCH2O. + NO2
(3a) CH3SCH2O.  HCHO + CH3S. major
(3b) + O2  CH3SCHO + HO2
. minor
(4b) CH3SCHO + OH.  CH3
. + COS + H2O
(Gas-phase chemistry)
Formation of carbonyl sulfide, COS
The COS yield is much smaller than 1 molecule per CH3SCH3 molecule,
because of
• decomposition of the alkoxy radical CH3SCH2O (3a) and
• much of the intermediate products are washed out (τ < week).
(1a) CS2 + OH + O2  COS + SO2 + H.
(1b) + h  CS2*
(2b) CS2* + O2  COS + O. (Crutzen, 1983)
As τCOS  years it is transported globally and reaches the stratosphere.
Other carbonyl sulfide, COS, sources, else than CH3SCH3 chemistry
Stratospheric aerosol
(1a) COS + h  S*
(2) S* + O2  SO + O.
(1b) O. + COS  SO + CO
(3) SO + O2  SO2 + O. (Crutzen, 1983)
COS stratospheric chemistry:
Its photolysis there produces SO2:
From SO2 H2SO4 is formed which explains the stratospheric sulfate layer during
periods of low volcanic activity
Example: cSO2 = 2 nmol m-3, cH2O2 = 40 nmol m-3, T = 298 K
(near Bermuda 1988)
1. Gas-phase: dcS(VI)/dt = 5.6×10-6 nmol m-3 s-1
2. Aqueous phase (L =3×10-8, pH=7):
dcSO4--/dt = k4 pH2O2 KH H2O2 pSO2 K*H SO2 (M s-1)
= (4×107× 10-7) × 40×10-9× 1×105× 2×10-9× 3.4×105
K*H SO2 = KH SO2 × (1 + KA1 / cH+ + KA1KA2 / c2
H+) =
= 3.4×105 M/atm
dcS(VI)/dt = dcS(VI)/dt (M s-1) × L (L m-3) × 109 (nmol mol-1) =
= 32×10-6 nmol m-3 s-1
Acidity formation in the troposphere: sulfuric acid
Heterogeneous reactions in the gas/water droplet system
In phase equilibrium
Less selectivity than in
the gas-phase
(Graedel & Weschler, 1981)
Reactivity of organics in the aqueous phase:
Overview OH reactions
Compilation of kaqu can be found in
N, S chemistry: Warneck, Phys Chem Chem Phys 1 (1999) 5471-5483
Herrmann, Chem Rev 103 (2003) 4691-4716
HCx chemistry: Herrmann, Chem Rev 103 (2003) 4691-4716
[L/mol/s]
(Rodhe et al., 2002)
acid deposition trends
Impacts of atmospheric acidity in ecosystems
Model (TM3) prediction
2000
2030 under CLE
[mg N/m²/a]
(Dentener et al., 2006)
acid deposition,
example NOy trends
[Tg/a]
2030 under MFR
Global N cycle, fluxes (Tg/a) +80%
1890
(Hibbard et al., 2006)
1990
Ammonia budget dcNH3/dt = Fe - kOH
(1) cNH3 - kdep
(1) cNH3
NHx = NH3 + NH4*
Emission trends (kt/a) in the EU-28 (EEA, 2014)
Ammonia and acidifying
ions trends
Europe
 NO3
-/SO4
2- and NH4
+/(SO4
2- + NO3
-) are increasing in
depositions
Ammonia and
acid precursor
gases trends
Asia
 No negative NH3
emission trend
(Duan et al., 2016)
(Li et al., 2017)
Gas-phase chemistry
NH3 + OH.  NH2
. + H2O k = 0.16×10-12 cm³/molec/s
(1) NH2
. + O2  NO + H2O k1 < 6×10-21 cm³/molec/s
(2) NH2
. + HO2
.  NH3 + O2 k2 = 34×10-12 cm³/molec/s
(3) NH2
. + NO  N2 + H2O k3 = 17×10-12 cm³/molec/s
(4) NH2
. + NO2  N2O + H2O k4 = 19×10-12 cm³/molec/s
(5) NH2
. + O3  NH2O. + O2 k5 = 0.16×10-12 cm³/molec/s
(6) NH2
. + RH  too slow to be of any significance
-dcNH3/dt = kOH
(1) cNH3 = kOH
(2) cOH cNH3; τOH = (kOH
(1))-1
 3 months for the global annual tropospheric mean (1.16×106 OH/cm3)
 10 days inner tropics near ground ( 107 OH/cm3; Spivakovsky et al., 2000)
-dcNH3/dt = kOH
(1) cNH3 + kdep
(1) cNH3
τair = (kOH
(1) + kdep
(1))-1
Cycling of ammonia
(following Manier)
Impacts of atmospheric acidity: acidification of soils
(Busch et al., 2001)
plants, bacteria
NO3
- + H+  ON
Deposition of acid: Effects in soils
RAINS (Regional Air Pollution Information and
Simulation Model) Asia project, IIASA
Critical loads exceedances in China 2005
(mapped) and cumulative distribution of
the critical load exceedances under
various future scenarios (Zhou et al., 2011;
Duan et al., 2016)
Percentage of total ecosystems area receiving nitrogen deposition above the critical loads
for eutrophication for the emissions of the year 2000 (meteorology of 1997)
(Sverdrup et al., 1990; IIASA)
Ecosystem response to nutrient N: Eutrophication (or: hyper-)
mass balance
Fcritical load:= FN uptake by biomass + FN immobilisation + Facceptable N leaching + Fdenitrification
Denitrification := biotic NO3
-  N2 or N2O
Nitrification := biotic NH3 or NH4
+  NO2
- or
NO3
Ammonification
:= biotic ON  NH3 or NH4
+
Critical loads concept to protect ecosystems
Wie müssen die Emissionen zurückgefahren werden, damit die Rezeptoren
der Immissionen (Böden, Oberflächengewässer, Grundwasserleiter) nicht
geschädigt werden ?
Wieviel Schädigung ist hinnehmbar ?
Mapping of critical loads „...below which harmful effects in ecosystem structure and
function do not occur according to present knowledge“:
Determines which loads of pollutants and combinations thereof will not cause
adverse effects, do not exceed ecosystem resilience (PNEC).
• + Protection of vulnerable areas is possible (protection of 95% of the area is
common)
• +Accounts for dynamics, mostly however based on steady state-assumption
and therefore neglecting the very slow dynamics of the soils
• - Scale problems when matching exposure (deposition model output) and
vulnerabilities (mapped ecosystems)
• - normative steps are not transparent
• Integrated Assessment Modelling (IAM) under the auspices of
the Convention on Long-range Transboundary Air Pollution
(CLRTAP): Study various scenarios of emissions and related
abatement costs + depositions and related exceedances of
thresholds (Alcamo et al., 1987, besides others)
Global atmospheric particulate matter sources (Tg/a)
1. Precursors
n: Vegetation 1000 (825-1150) (Guenther et al., 1995)
n: Oceans 26 (Eichmann et al., 1980)
a: Industry, transport 100 (90-100) (Ehhalt, 1986; Müller, 1992)
Gas-to-particle-conversion efficiencies
n:  5% 55 (40-200) (Andreae, 1995)
n:  2% 18.5 (Griffin et al., 1999)
a:  6% 10 (5-25) (Andreae, 1995)
2. direct emission
n: Vegetation 50 (26-80)
n: Soils 11
a: Biomass burning 80 (50-140)
a: Industrial dust 100 (40-130)
n: Sea salt 3340 (1000-6000)
n: Mineral dust 2150 (1000-3000) (Penner et al., 2001)
Aerosol = particles dispersed in air + gas-
phase
Directly emitted = primary particles /
aerosols
Formed in air (by gas-to-particleconversion
processes) = secondary particles
/ aerosols
Atmospheric aerosol, its composition, surface and bulk particle
reactions
Introduction, significance, sources
Aerosol distributions (on 3.8.01) with low and high sub-micron mass
fraction
(MODIS aerosol optical density, Martin & Kaufman, NASA)
3340 (1000-6000) Tg/a sea salt, 2150 (1000-3000) Tg/a mineral dust,
450 (260-840) Tg/a secondary particles, ...
 Potential to affect insolation, precipitation, temperatures...
1. Human health: Respiratory and cardiovascular diseases
and short-term effects
2. Provides matrix for heterogeneous reactions and is
carrier for semivolatile compounds  3.1.4
3. Radiative and cloud nucleation effects (climate, socalled
direct and indirect aerosol effects)
Why is the atmospheric aerosol relevant ?
IPCC, 2007
 Potential to affect insolation, precipitation, temperatures...
Radiative and cloud nucleation effects (climate, so-called direct and
indirect aerosol effects)
IPCC, 2013
Sulfate aerosols: cooling
Optical and hygroscopic properties
• Scattering (‚direct effect‘) + warming due to absorption (‚semi-direct effect‘):
–1.2 W/m² (earth surface)
• Clouds: increase optical thickness and albedo due to increased droplet number
concentration (‚1st indirect effect‘): –1.5 ± 0.5 W/m² (Lohmann & Feichter, 2001)
 Instead of  +0.7°C global warming we had without anthropogenic aerosols 
+1.7°C !
Zonal (S pole – N pole) mean
temperature changes 1990-1850:
GHG, aerosols, GHG + aerosols
(Feichter et al., 2004)
3. Radiative and cloud nucleation effects (climate, so-called direct and
indirect aerosol effects)
Gerhard Lammel: “Trends and Advances in Atmospheric and
Environmental Chemistry"
Where: Bohunice campus A29, room 411
When: 25.9., 27.9., 26.10., 27.10. 10:00, 20.11.(?), 21.11.(?)17
Introduction: pressure, law of mass action
Thermal reactions, radiation, photochemical processes
Tropospheric ozone: hydrocarbon chemistry, role of nitrogen oxides
Cloud chemistry: Ozone, acidity formation, dimethyl sulphide
Atmospheric aerosol, its composition, surface and bulk particle reactions
Trace substance mass budgets, surface cycling: Emissions, deposition, re-
volatilisation
Adverse health effects
• Fine PM reaches the lung: < 10 µm (PM10), at least < 5 µm, macrophages remove
1/3 (the larger), rest remains in the alveolar region or even reaches into the lymphatic
and blood circulations
Aerosol ↔ Health
PMx = particulate matter
smaller than x µm by size
TSP = total suspended
particulate matter
• PM2.5 carries numerous organic and inorganic substances, including toxics (nitroPAHs,
dioxins, …)  pulmonary and cardiovascular diseases (e.g., elevated fatal
stroke risk), mutagenic, nervous system impairment. A no-effectconcentration/threshold
value cannot be identified
• WHO estimate (2006): Mortality in most polluted
cities could be reduced by 15%
• EU Comm. (2007): 2 mn premature deaths per year
globally, 0.39 mn in EU (2007). Reduction to 0.27 mn
in 2020 under current legislation, 0.19 mn feasible.
Particle size dependent deposition in the respiratory tract
Protection through deposition from
<0.1 µm: ineffective
Macrophages and innate immune system need to react
(Dombu & Betbeder, 2013)
PREMATURE DEATHS ASSOCIATED WITH ENVIRONMENTAL
RISK
By 2030, PM surpasses unsafe water as the leading environmental cause of
premature deaths.
[OECD, 2012]
   fine   coarse   
M.Ebert, S.Weinbruch et al.,
2000
TU Darmstadt
Coagulation
Sedimentation
Diffusion
Nucleation
Evaporation
Condensation
Convection
Other
external
forces
Aerosol microphysical processes
Aerosol processes
Fuzzi et al., 2006
Courtesy of: Cambra-López et al., 2010
Nucleation events:
Reasons for occurrence of nucleation events unclear. No simple correlations,
key factors unknown. Example: 3 different events on Hohenpeissenberg 1998-
2000 (Birmili et al., 2003).
The nucleation rate is
mostly 2nd order in H2SO4,
in general 1st to 2nd. This
suggests the prevalence of
a bimolecular reaction
(collision) of 2 clusters
with each one H2SO4
molecule for formation of
the critical cluster
(Weber et al., 2006).
Primary particle formation (nucleation)
condensational growth
n1 H2SO4 + n2 H2O + n3 NH3 (?) + RCOOH (??)  critical cluster  ultrafine particle
Removal processes - size dependent residence time
D/2
[µm]
τ
[d]
s
[km]
z
[m]
0.001 0.01 8 20
0.01 1 800 2000
0.1 10 8000 20000
1 10 8000 20000
10 1 800 2000
100 0.01 8 20
(Franklin et al., 2000)
empirical expression:
τdry = f(D) = /[(D/0.6)2 + (D/0.6)-2]; D [µm],  = 1.28×108 s
τwet < 106 s (Jaenicke, 1988)
PROVEN PATHWAYS
OF REGIONAL AND INTERCONTINENTAL TRANSPORT OF AEROSOLS
Marx & McGowan, 2010
Main components – Trends
Weekly filter samples, PM10, PM2.5 ’95-‘02 bzw. ’99-’02 (PM1)
Spindler et al., 2004
0
10
20
30
40
50
60
30.12.94 30.12.95 30.12.96 30.12.97 30.12.98 30.12.99 30.12.00 30.12.01 30.12.02
Partikelmassenkonzentration[µg/m³]
PM10 PM2.5
PM1 since 1999 Linear (PM10)
Linear (PM2.5) Linear (PM1 since 1999)
Aerosol sources (globally, TgE/a oder Tg/a)
Precursors anthr. natural
NOx 41 31 10
NH3 54 (40-70) 43 11
SO2 88 (67-130) 79 9
DMS 25 (12-42) 0 25
VOCs 236 (100-560) 109 127 (only terpenes)
Primary
Carbonaceous (OC)
Biomass burning 54 (45-80)
Fossil fuel burning 28 (10-30)
biogenic 56 (0 – 90)
Black carbon (soot)
Biomass burning 5.7 (5-9)
Fossil fuel burning 6.6 (6-8)
Industrial dust 100 (40-130)
Sea salt 3340 (1000-6000)
Mineral dust 2150 (1000-3000)
(Penner et al., in IPCC, 2001) (UBA)
Aerosol concentrations, chemical composition in EuropeChemical composition
Globally: Jaenicke: Aerosol physics and chemistry,
Landolt-Börnstein, 1988
Europe:
Putaud et al.,
EU-Report 2002 =
van Dingenen et al.,
Atmos. Environ. 2004
Aerosol chemical composition
Eur. Aer. Phenomenology
(Putaud et al., 2002)
strong temperature dependence of the N(V)
phase equilibrium NH3 + HNO3 = NH4NO3:
for rh < rhD:
pNH3 * pHNO3 = 0.12 ppbv² (278 K),
2.0 ppbv² (288 K),
28 ppbv² (298 K)
Humidity dependence:
(Stelson & Seinfeld, 1982)
Y = [NH4NO3]/{[NH4NO3] + 3 [NH4(SO4)2]}
Ions volatile, and non-volatile:
Winter
0.5 Cl- + 1.3 NO3
- + 0.5 SO4
2- + 0.5 Na+ + 2.3 NH4
+ + 0.1 K+ + 0.05 Mg2+ + 0.33 Ca2+
- (0.9 NH4NO3 - 0.2 NH4Cl - 0.1 HCl) =
Summer
0.2 Cl- + 0.4 NO3
- + 0.5 SO4
2- + 0.5 Na+ + 1.2 NH4
+ + 0.1 K+ + 0.05 Mg2+ + 0.33 Ca2+
Potential to reduce fine particulate matter (PM) ?
Example emission reductions NH3
(courtesy of Reimer, FU Berlin 2006)
Expected effects are not very large
NH3 emissions are underestimated
PM10 (% reduction) for scenario of 0 NH3
emissions in eastern Germany, Poland and
Ukraine
A large fraction of the organic carbon (OC, POM) is water
soluble (WSOC)
(...and, hence, suitable as cloud condensation nucleus (CCN))
Continental aerosol consists of (each 25-50%):
• aliphatic polyols (mostly sugars) and polyethers (polyphenols)
• low-molecular aliphatic and other multifunctional compounds, e.g. R(COOH)1-2
• unsaturated aliphatic and aromatic polyacids of various lipophilicity („humiclike“),
M = 200-500 Da, sources: Oxidation of soot, acid catalyzed polymerisation of
terpenes (Havers et al., 1998; Fuzzi et al., 2001; Krivacsy et al., 2001; Decesari et al., 2002; Gelencser
et al., 2003; Puxbaum et al., 2003)
Continental aerosol (Winkler, 1974)
Aerosol sources, size segregated
Air in Riverside, CA, 25.9.1996 (Kleeman et al., 1999)
• Emission inventory
(source distribution,
characteristics)
• Atmosphere model
covering transport and
transformations
Sources for aerosol inorganic ions,
Los Angeles 24.-25.9.1996 (Mysliwiec & Kleeman, 2002)
• Emission inventory
(source distribution,
characteristics)
• Atmosphere model
covering transport and
transformations
Source contributions to OC: urban
Southern California,
(Rogge et al., 1996; Schauer et al., 1996)
Total fine part. OC emitt. 30 t/d
Meat cooking 21%
Road abrasion 16%
Open fires 14%
Vehicles without cat.
converter 12%
Diesel vehicles 6.2%
Lacquing 4.8%
Forest fires 2.9%
Vehicles without cat.
converter 2.9%
Tobacco smoke 2.7%
0
2
4
6
8
10
12
14
16
18
20
W
-L.A
.1982
Rubidoux1982
Gentwinter1998
entsummer1998
winter1998-2000
summer1998-99
c(µg/m³)
res id OC
res unid OC
el unres OC
non-ex non-el OC
EC
identified organics Los Angeles
12%
50%
4%
6%
0%
2%
6%
20%
n-alkanes
fatty acis
DCAs, oxoMCAs
diterpenoic acids
lignin pyrolysis products
PAHs
other
aromatic polycarboxylic acids
identified organics Gent / winter
23%
53%
3%
9%
5% 6%
1% 0%
identified organics Gent / summer
35%
44%
9%
8% 0%0%4% 0%
(Schauer et al, 1996; Kubátova et al., 2001)
Ozonolysis of alkenes: Terpenes (Griffin et al., 1999ff; Iinuma et al., 2004)
C14-1-en: Smog chamber UCR (Ziemann et al., 2000):
C14-1-en + O3 
 SOA
Secondary particle sources: SOA formation
• biogenic primary emitted, including biologically
effective substances (proteins, toxins)
• biogenic secondary (formed from terpenes, besides other)
• biopolymers and fragments thereof, eventually photochemically formed polymers
(Gelencser et al., 2003)
for example, xcellulose = 1-2 % in Wien (Kunit & Puxbaum, 1996);
• microorganisms, fragments thereof, macroscopic particles (hairs, droplets,...)
• anthropogenic primary (cooking vapours, tobacco smoke…)
• anthropogenic secondary
EC/TC Protein/TC
Urban: ~ 60 % ~ 4 %
Rural: ~ 30 % ~ 30 %
Alpine: ~ 30 % ~ 20 %
(Franze et al., 2003; Fehrenbach,
2007)
POM molecular weight:
A large fraction of the water insoluble fraction is high molecular
= amorphous C + shell of adsorbed molecules and/or partly oxygenated C
+ adsorbed water molecules
• Strong sorbent
• Light absorbing
• Hydrophobic (initially)
soot particle shell, core (Hoffmann et al., 2007)
3.4.2.4 Soot
flame soot surface chemical composition (Smith et al.,
= nanosphere-soot particles
Curvature probably caused by 5-ring structures (fullerenes!) or by lacking
C atoms
(Buseck et al., 2014)
4 size modes
7 chemical components
(Stier et al., 2005)
+ PAHs
• Soot and POM distributions are not easily available
• In most aerosol models: Hygroscopic soot is formed from lipophilic soot (BC)
after a fixed time (‚aging‘). Example: ECHAM5-HAM Aerosol Model
(Tang, 1976; Winkler & Junge, 1972)
Deliquescence Density
humidity, rhD [g cm-3]
NaCl 75% 2.16
CaCO3 - 1.77
(NH4)2SO4 80% 1.77
NH4HSO4 39% 1.78
NH4NO3 62% 1.72
Particulate matter water
uptake:
Growth of particulate
matter containing inorganic
salts is smooth (unlike for
pure salts)
3.4.2.5 Water
dt: Liqueszenzfeuchte
-dc1/dt = k(2) c1 c2; k (2) [1/M/s]
(Graedel & Weschler, 1981)
Particulate matter provides an aqueous phase:
Overview trace species concentrations