2011; Zhang et al. 2012; Wu et al. 2016; Tian et al. 2018). As a result, the Chinese
government has started to curb atmospheric NO x emissions since 2010, while NH 3
has not been regulated yet. In this context, an evaluation of reactive N emission,
deposition, and budget in China is essential for impact assessment and national N
regulation.
Atmospheric NH 3 and NO x emissions have increasingly attracted the public
attention in China. In Chap. 2, Zhang Q et al. assessed spatial-temporal variations
in NH 3 , NO x , and SO 2 emissions in China and related uncertainties. The results
indicate that the total reactive N emission increased continuously over the past three
decades, after which the NO x emission started to decline from 2011. However, the
NH 3 emission is expected to remain consistently high levels. Atmospheric N deposition is one of the main pathways of external N inputs to terrestrial and marine
ecosystems. In Chap. 3, Liu et al. reviewed monitoring methods, monitoring networks, and monitoring results of N wet and dry deposition in China. In Chap. 4,
Zhang L et al. reviewed numerical modeling approaches for simulating atmospheric
N deposition and their recent applications on N deposition to China. Both monitoring and modeling results indicated an increase of N deposition during the 1980s and
2000s. The annual total N deposition to China was estimated to be 7.9–20.1 Tg N
year
À1 , and reduced N (NH x ) accounted for 60–80% of the total N deposition. In
Chap. 5, Gu et al. evaluated the budgets for reactive N in China from 1980 to 2015.
The results indicate a tripling of anthropogenic reactive N creation, which was
associated with an even more rapid increase in N fluxes to the atmosphere and
hydrosphere. These increasing N flows may cause consequent threats to human
health, the sustainability of crop production and sensitive ecosystems, and the
environment.
1.3 The Contribution of Reactive Nitrogen to Air Pollution
in China
Reactive N plays a significant role in atmospheric chemistry and is closely associated
with air pollution, such as haze, troposphere O 3 , and acid deposition (Liu et al.
2017). In Chap. 6, Pan et al. reviewed the mechanisms of aerosol formation related to
reactive N and the contribution of reactive N to haze pollution in China. Specifically,
nitrate and ammonium are major compounds of atmospheric particulate matter,
contributing approximately one-third of fine particulate matters (e.g., PM 2.5 ).
Although the concentration of amines in the atmosphere is probably two or three
orders of magnitude lower than that of ammonia, amines can significantly assist the
growth of both neutral and ionic clusters. In Chap. 7, Feng et al. reviewed the
mechanism of O 3 formation and summarized the spatial-temporal patterns of
ground-level O 3 in China. Generally, high O 3 concentrations frequently occur in
China’s major metropolitan agglomerations such as the Jing-Jin-Ji region, the
Yangtze River Delta, and the Pearl River Delta. Moreover, the ambient O 3
1 An Overview of Atmospheric Reactive Nitrogen in China from a Global Perspective
5
government has started to curb atmospheric NO x emissions since 2010, while NH 3
has not been regulated yet. In this context, an evaluation of reactive N emission,
deposition, and budget in China is essential for impact assessment and national N
regulation.
Atmospheric NH 3 and NO x emissions have increasingly attracted the public
attention in China. In Chap. 2, Zhang Q et al. assessed spatial-temporal variations
in NH 3 , NO x , and SO 2 emissions in China and related uncertainties. The results
indicate that the total reactive N emission increased continuously over the past three
decades, after which the NO x emission started to decline from 2011. However, the
NH 3 emission is expected to remain consistently high levels. Atmospheric N deposition is one of the main pathways of external N inputs to terrestrial and marine
ecosystems. In Chap. 3, Liu et al. reviewed monitoring methods, monitoring networks, and monitoring results of N wet and dry deposition in China. In Chap. 4,
Zhang L et al. reviewed numerical modeling approaches for simulating atmospheric
N deposition and their recent applications on N deposition to China. Both monitoring and modeling results indicated an increase of N deposition during the 1980s and
2000s. The annual total N deposition to China was estimated to be 7.9–20.1 Tg N
year
À1 , and reduced N (NH x ) accounted for 60–80% of the total N deposition. In
Chap. 5, Gu et al. evaluated the budgets for reactive N in China from 1980 to 2015.
The results indicate a tripling of anthropogenic reactive N creation, which was
associated with an even more rapid increase in N fluxes to the atmosphere and
hydrosphere. These increasing N flows may cause consequent threats to human
health, the sustainability of crop production and sensitive ecosystems, and the
environment.
1.3 The Contribution of Reactive Nitrogen to Air Pollution
in China
Reactive N plays a significant role in atmospheric chemistry and is closely associated
with air pollution, such as haze, troposphere O 3 , and acid deposition (Liu et al.
2017). In Chap. 6, Pan et al. reviewed the mechanisms of aerosol formation related to
reactive N and the contribution of reactive N to haze pollution in China. Specifically,
nitrate and ammonium are major compounds of atmospheric particulate matter,
contributing approximately one-third of fine particulate matters (e.g., PM 2.5 ).
Although the concentration of amines in the atmosphere is probably two or three
orders of magnitude lower than that of ammonia, amines can significantly assist the
growth of both neutral and ionic clusters. In Chap. 7, Feng et al. reviewed the
mechanism of O 3 formation and summarized the spatial-temporal patterns of
ground-level O 3 in China. Generally, high O 3 concentrations frequently occur in
China’s major metropolitan agglomerations such as the Jing-Jin-Ji region, the
Yangtze River Delta, and the Pearl River Delta. Moreover, the ambient O 3
1 An Overview of Atmospheric Reactive Nitrogen in China from a Global Perspective
5