from 1980 to 2010 but has stabilized afterwards. We discuss the uncertainties in
quantifying dry, wet and total N deposition. We also propose recommendations to
address current challenges in developing a long-term, open-access deposition monitoring network with reasonable accuracy and representativeness in China.
3.1 Introduction
Nitrogen (N) deposition is a significant component of the global N cycle which has
been hastened by humans. A surplus of N deposition led to adverse ecological
effects, including the loss of biodiversity (Bobbink et al. 2010), unbalanced nutrition
(Galloway et al. 2003), soil acidification (Yang et al. 2015; Zhu et al. 2016) and
excessive nutrients in bodies of water (Fenn et al. 2003). Nitrogen deposition,
especially oxidized N deposition, has declined or stabilized in Europe and the
USA since 1990, mainly due to nitrogen oxides (NO x ) emission reductions (Erisman
et al. 2015; Zhang et al. 2018; Du et al. 2014; Du 2016). In China, emissions of both
ammonia (NH 3 ) and NO x have been on the rise since the 1980s, due to an increase in
industrialization and widespread farming (Liu et al. 2011, 2013, 2016a), but the
trend has slowed and/or stabilized recently due to some strict air pollution control
measures (also see Chap. 2, in this book). The increase in reactive N (N r ) emissions
has generated public fears related to air quality and how this relates to atmospheric N
deposition in China (Wu et al. 2016; Xu et al. 2018a, b).
Quantification of the input of N r from the atmosphere to terrestrial and aquatic
ecosystems has been of concern for decades. Many techniques have been developed
to measure pathways of deposition: wet, dry and total deposition. Wet deposition can
be readily measured with reliable accuracy, whereas direct measurement of dry
deposition, especially over the long term, is still considered a challenging hurdle
due to a broad array of nitrogen-rich species in gases and aerosols (Xu et al. 2015)
and technical difficulties related to measuring their deposition, particularly in remote
regions.
This chapter presents the “state of the art” for N deposition monitoring in China.
It discusses how far we have progressed, which deposited N r species can be
quantified by what methods, how effective are the monitoring networks, what is
the magnitude of different types of N deposition and what future research is required.
The chapter contains a detailed review of measurement methods for dry, wet and
total N deposition, followed by a short summary of monitoring networks in China,
America, Europe and Africa. An overview of the magnitude and spatio-temporal
inconsistency of N deposition in mainland China and its coastal seas is presented,
based on recent N deposition monitoring and/or modelling studies.
42
X. Liu et al.
quantifying dry, wet and total N deposition. We also propose recommendations to
address current challenges in developing a long-term, open-access deposition monitoring network with reasonable accuracy and representativeness in China.
3.1 Introduction
Nitrogen (N) deposition is a significant component of the global N cycle which has
been hastened by humans. A surplus of N deposition led to adverse ecological
effects, including the loss of biodiversity (Bobbink et al. 2010), unbalanced nutrition
(Galloway et al. 2003), soil acidification (Yang et al. 2015; Zhu et al. 2016) and
excessive nutrients in bodies of water (Fenn et al. 2003). Nitrogen deposition,
especially oxidized N deposition, has declined or stabilized in Europe and the
USA since 1990, mainly due to nitrogen oxides (NO x ) emission reductions (Erisman
et al. 2015; Zhang et al. 2018; Du et al. 2014; Du 2016). In China, emissions of both
ammonia (NH 3 ) and NO x have been on the rise since the 1980s, due to an increase in
industrialization and widespread farming (Liu et al. 2011, 2013, 2016a), but the
trend has slowed and/or stabilized recently due to some strict air pollution control
measures (also see Chap. 2, in this book). The increase in reactive N (N r ) emissions
has generated public fears related to air quality and how this relates to atmospheric N
deposition in China (Wu et al. 2016; Xu et al. 2018a, b).
Quantification of the input of N r from the atmosphere to terrestrial and aquatic
ecosystems has been of concern for decades. Many techniques have been developed
to measure pathways of deposition: wet, dry and total deposition. Wet deposition can
be readily measured with reliable accuracy, whereas direct measurement of dry
deposition, especially over the long term, is still considered a challenging hurdle
due to a broad array of nitrogen-rich species in gases and aerosols (Xu et al. 2015)
and technical difficulties related to measuring their deposition, particularly in remote
regions.
This chapter presents the “state of the art” for N deposition monitoring in China.
It discusses how far we have progressed, which deposited N r species can be
quantified by what methods, how effective are the monitoring networks, what is
the magnitude of different types of N deposition and what future research is required.
The chapter contains a detailed review of measurement methods for dry, wet and
total N deposition, followed by a short summary of monitoring networks in China,
America, Europe and Africa. An overview of the magnitude and spatio-temporal
inconsistency of N deposition in mainland China and its coastal seas is presented,
based on recent N deposition monitoring and/or modelling studies.
42
X. Liu et al.