The above studies indicate that abatement of SO 2 or NO x emissions or both has
limited effectiveness on the reduction of the PM 2.5 concentration reduction and NH 3
may play a more critical role in inorganic aerosol formation. Fu et al. (2017) found
that satellite-observed NH 3 increased from 2008 to 2014 and the increase in NH 3
emissions reduced the effectiveness of the controls on the PM 2.5 concentration that
were achieved via reductions in SO 2 and NO x emissions over the years. They
conducted three sensitivity simulations based on the standard scenario. In the first
sensitivity test (SI), they set the decrease in SO 2 and NO x emissions 55% below the
standard simulation, and NH 3 remained unchanged. In the second test (SII), they set
the decrease in SO 2 and NO x emissions to 55% and the decrease in NH 3 to 30%. In
the third test (SIII), they let SO 2 and NO x remain unchanged, but NH 3 was decreased
by 30%. In comparing SI and SII, they illustrated that that the 30% reduction in NH 3
resulted in an additional 10% reduction in the SNA concentration over East China, as
well as an additional 22% reduction in NO 3
À
. A difference between SIII and the
standard scenario is apparent in the PM 2.5 response to the change in NH 3 emissions
“at present,” and the difference between SII and SI is the PM 2.5 response to the
change in NH 3 emissions “in the future.” The result revealed that a NH 3 reduction at
present leads to a 31% decrease in the NO 3
À concentration, but it is 28% in the
future, indicating that the abatement of NH 3 emissions is more effective at reducing
the PM 2.5 concentration at present than in the future.
In fact, the Chinese government enforces strict emission control strategies for SO 2
and NO x , but little attention is paid to NH 3 . The model sensitivity analysis emphasized the importance of controlling NH 3 emissions with regard to reducing PM 2.5
concentrations over China.
6.4.3 Role of NO x and NH 3 Emission Control During Special
Major Events
With the rapid development of society and the economy, China has become increasingly influential in the world. More and more major international events are held in
Beijing, such as the 29th Olympic Games in 2008, the Asia-Pacific Economic Cooperation (APEC) Summit in November 2014, and the Grand Military Parade in
September 2015. To guarantee the air quality during major events, the Chinese
government imposed a set of measures to reduce emissions of pollutants, which provides a valuable opportunity to investigate the response of the PM 2.5 concentration to
changes in its precursor emissions. These measures include temporary closure of
factories and small power plants, suspension of construction activities, and the “oddeven” traffic restrictions in Beijing and surrounding regions (Shen et al. 2011). A
comparison of pollutant concentrations between the duration of major events and
periods before/after events reveals that temporal emission control strategies are of
noticeable help in improving air quality during major events (Cermak and Knutti 2009).
6 Contribution of Atmospheric Reactive Nitrogen to Haze Pollution in China
127
limited effectiveness on the reduction of the PM 2.5 concentration reduction and NH 3
may play a more critical role in inorganic aerosol formation. Fu et al. (2017) found
that satellite-observed NH 3 increased from 2008 to 2014 and the increase in NH 3
emissions reduced the effectiveness of the controls on the PM 2.5 concentration that
were achieved via reductions in SO 2 and NO x emissions over the years. They
conducted three sensitivity simulations based on the standard scenario. In the first
sensitivity test (SI), they set the decrease in SO 2 and NO x emissions 55% below the
standard simulation, and NH 3 remained unchanged. In the second test (SII), they set
the decrease in SO 2 and NO x emissions to 55% and the decrease in NH 3 to 30%. In
the third test (SIII), they let SO 2 and NO x remain unchanged, but NH 3 was decreased
by 30%. In comparing SI and SII, they illustrated that that the 30% reduction in NH 3
resulted in an additional 10% reduction in the SNA concentration over East China, as
well as an additional 22% reduction in NO 3
À
. A difference between SIII and the
standard scenario is apparent in the PM 2.5 response to the change in NH 3 emissions
“at present,” and the difference between SII and SI is the PM 2.5 response to the
change in NH 3 emissions “in the future.” The result revealed that a NH 3 reduction at
present leads to a 31% decrease in the NO 3
À concentration, but it is 28% in the
future, indicating that the abatement of NH 3 emissions is more effective at reducing
the PM 2.5 concentration at present than in the future.
In fact, the Chinese government enforces strict emission control strategies for SO 2
and NO x , but little attention is paid to NH 3 . The model sensitivity analysis emphasized the importance of controlling NH 3 emissions with regard to reducing PM 2.5
concentrations over China.
6.4.3 Role of NO x and NH 3 Emission Control During Special
Major Events
With the rapid development of society and the economy, China has become increasingly influential in the world. More and more major international events are held in
Beijing, such as the 29th Olympic Games in 2008, the Asia-Pacific Economic Cooperation (APEC) Summit in November 2014, and the Grand Military Parade in
September 2015. To guarantee the air quality during major events, the Chinese
government imposed a set of measures to reduce emissions of pollutants, which provides a valuable opportunity to investigate the response of the PM 2.5 concentration to
changes in its precursor emissions. These measures include temporary closure of
factories and small power plants, suspension of construction activities, and the “oddeven” traffic restrictions in Beijing and surrounding regions (Shen et al. 2011). A
comparison of pollutant concentrations between the duration of major events and
periods before/after events reveals that temporal emission control strategies are of
noticeable help in improving air quality during major events (Cermak and Knutti 2009).
6 Contribution of Atmospheric Reactive Nitrogen to Haze Pollution in China
127