6.2 Mechanisms of Haze Formation Related
to Atmospheric Nr
6.2.1 Ammonia
Although the primary compounds responsible for nucleation are sulfuric acid
(H 2 SO 4 ) and water (H 2 O) (Boy et al. 2005; Sihto et al. 2006), the H 2 SO 4 -H 2 O
cluster cannot explain the observed formation and growth of atmospheric particles.
Other precursors have been found including organic compounds (Jokinen et al.
2015; Troestl et al. 2016), ions (Kirkby et al. 2016; Wagner et al. 2017), NH 3
(Kirkby et al. 2011), amide (Barnes et al. 2010; Chen et al. 2017), and amines
(Almeida et al. 2013; Elm et al. 2017). NH 3 is the most abundant basic gas in the
atmosphere, which can neutralize sulfuric acids. This neutralization reduces the
surface vapor pressure of particles and facilitates new particle formation (NPF).
Wang et al. (2016) suggested that NH 3 effectively neutralized acidic precursor, while
sulfate (SO 4
2À
) had been rapidly produced during the polluted period. NH 3 can also
neutralize nitric acid through surface reaction and contribute to aerosol nucleation.
The ammonium nitrate (NH 4 NO 3 ) formed in nucleation and organic condensation
vapors can accelerate the initial growth of new particles. It is estimated that NH 3 can
enhance the initial growth rate of aerosol by 8–90% and its size growth potential by
7–108% (Li et al. 2018). Alkylamines have been identified as important precursor of
atmospheric secondary aerosols (Kulmala et al. 2013). Recent laboratory experiment
has found that the presence of NH 3 stimulates nucleation rates by another 1–2 orders
of magnitude relative to the alkylamines alone (Temelso et al. 2018). The binding
strength of smaller clusters is determined by the basicity of the bases in the gas
phase, whereas the basicity in the aqueous phase is more important for larger
particles.
The strong acid-base interaction between methyl hydrogen sulfate (MHS) and
NH 3 or dimethyl-amine (DMA) transfer a proton from MHS to NH 3 or DMA since
the hydrogen bonding criteria is inferior to the electron density and Laplacian at the
bond critical points for most of the complexes (Sheng et al. 2017). Theoretical
calculations based on thermodynamic data and reactants concentrations suggest
the important participation of MHS to new particle formation. Zhang et al. (2017a)
investigated how glycolic acid participate into the formation of clusters by H 2 SO 4
and NH 3 .The glycolic acid serves as a mediating bridge for the formation of H 2 SO 4 -
NH 3 -based clusters which seems like a “catalytic” enhancement mechanism.
Bandyopadhyay et al. (2017) showed that NH 3 could efficiently catalyze the hydrolysis of SO 3 . Based on rate coefficients and the magnitude of relative potential
energies, NH 3 is one of the most effective catalysts and could be a key factor in
the formation of sulfuric acid in the troposphere. It is calculated that the coefficient of
NH 3 -catalyzed reaction at 298 K was approximately 10
5
–10
7 times greater than that
of water-catalyzed reaction.
6 Contribution of Atmospheric Reactive Nitrogen to Haze Pollution in China
115
to Atmospheric Nr
6.2.1 Ammonia
Although the primary compounds responsible for nucleation are sulfuric acid
(H 2 SO 4 ) and water (H 2 O) (Boy et al. 2005; Sihto et al. 2006), the H 2 SO 4 -H 2 O
cluster cannot explain the observed formation and growth of atmospheric particles.
Other precursors have been found including organic compounds (Jokinen et al.
2015; Troestl et al. 2016), ions (Kirkby et al. 2016; Wagner et al. 2017), NH 3
(Kirkby et al. 2011), amide (Barnes et al. 2010; Chen et al. 2017), and amines
(Almeida et al. 2013; Elm et al. 2017). NH 3 is the most abundant basic gas in the
atmosphere, which can neutralize sulfuric acids. This neutralization reduces the
surface vapor pressure of particles and facilitates new particle formation (NPF).
Wang et al. (2016) suggested that NH 3 effectively neutralized acidic precursor, while
sulfate (SO 4
2À
) had been rapidly produced during the polluted period. NH 3 can also
neutralize nitric acid through surface reaction and contribute to aerosol nucleation.
The ammonium nitrate (NH 4 NO 3 ) formed in nucleation and organic condensation
vapors can accelerate the initial growth of new particles. It is estimated that NH 3 can
enhance the initial growth rate of aerosol by 8–90% and its size growth potential by
7–108% (Li et al. 2018). Alkylamines have been identified as important precursor of
atmospheric secondary aerosols (Kulmala et al. 2013). Recent laboratory experiment
has found that the presence of NH 3 stimulates nucleation rates by another 1–2 orders
of magnitude relative to the alkylamines alone (Temelso et al. 2018). The binding
strength of smaller clusters is determined by the basicity of the bases in the gas
phase, whereas the basicity in the aqueous phase is more important for larger
particles.
The strong acid-base interaction between methyl hydrogen sulfate (MHS) and
NH 3 or dimethyl-amine (DMA) transfer a proton from MHS to NH 3 or DMA since
the hydrogen bonding criteria is inferior to the electron density and Laplacian at the
bond critical points for most of the complexes (Sheng et al. 2017). Theoretical
calculations based on thermodynamic data and reactants concentrations suggest
the important participation of MHS to new particle formation. Zhang et al. (2017a)
investigated how glycolic acid participate into the formation of clusters by H 2 SO 4
and NH 3 .The glycolic acid serves as a mediating bridge for the formation of H 2 SO 4 -
NH 3 -based clusters which seems like a “catalytic” enhancement mechanism.
Bandyopadhyay et al. (2017) showed that NH 3 could efficiently catalyze the hydrolysis of SO 3 . Based on rate coefficients and the magnitude of relative potential
energies, NH 3 is one of the most effective catalysts and could be a key factor in
the formation of sulfuric acid in the troposphere. It is calculated that the coefficient of
NH 3 -catalyzed reaction at 298 K was approximately 10
5
–10
7 times greater than that
of water-catalyzed reaction.
6 Contribution of Atmospheric Reactive Nitrogen to Haze Pollution in China
115