allocated to high-resolution grids based on a digital road map and weighting factors
of vehicle kilometers traveled (VKT) by vehicle and road type (Zheng et al. 2014).
For NH 3 , a process-based model developed by Peking University is
recommended to estimate NH 3 emissions, which parameterized the spatial and
temporal variations of emission factors with extensive consideration of multiple
factors (Huang et al. 2012; Kang et al. 2016). For fertilizer applications, fertilizer
type, soil property, fertilizer application method, application rate, ambient temperature, wind speed, and in situ measurements of NH 3 flux were used to develop
monthly and gridded NH 3 emission factors. For livestock waste, emissions were
estimated based on a mass-flow methodology by tracing the migration and volatilization of nitrogen from each stage of livestock manure management.
2.3 Evolution of SO 2 and NO x Emissions in China
Using the updated methods and input data for each sector described in the previous
sections, significant improvements in total emission estimates have been made
during the last several decades. As is reasonable, emission estimates differ among
inventories, due to differences in the compilation methods and data used (Li et al.
2017b). Recognizing these differences, we focus here on reviewing the best available knowledge of the emission characteristics of SO 2 and NO x , as well as their
driving forces to the emission changes in China.
2.3.1 Emission Estimates
The long-term emissions of SO 2 and NO x since 2000, derived from various studies,
are shown and compared in Fig. 2.1. The sectoral distributions of these two pollutants are shown in Fig. 2.2. China’s anthropogenic emissions are estimated to have
declined by 62% for SO 2 and 17% for NO x since 2010. Most of these emission
reductions have been achieved since 2013 when the Clean Air Action was enacted
and implemented. SO 2 and NO x are the only air pollutants that were incorporated
into national economic and social development plans with emission reduction targets
in China. The 12th Five-Year Plan required the total national emissions of SO 2 and
NO x to be cut by 8% and 10% from 2011 to 2015, respectively, while the actual
reductions were much larger than planned due to the more stringent pollution control
requirements implemented after 2013. Given that China’s economy is growing
rapidly, China’s emissions are decoupling from population, economic, and energy
consumption growth (Zheng et al. 2018). China’s gross domestic product grew by
7.6% per year from 2010 and achieved 67% growth by 2017; however, China’s
emissions flattened out from 2010 to 2013 followed by a significant decrease after
2013, according to the MEIC estimates.
18
Q. Zhang et al.
of vehicle kilometers traveled (VKT) by vehicle and road type (Zheng et al. 2014).
For NH 3 , a process-based model developed by Peking University is
recommended to estimate NH 3 emissions, which parameterized the spatial and
temporal variations of emission factors with extensive consideration of multiple
factors (Huang et al. 2012; Kang et al. 2016). For fertilizer applications, fertilizer
type, soil property, fertilizer application method, application rate, ambient temperature, wind speed, and in situ measurements of NH 3 flux were used to develop
monthly and gridded NH 3 emission factors. For livestock waste, emissions were
estimated based on a mass-flow methodology by tracing the migration and volatilization of nitrogen from each stage of livestock manure management.
2.3 Evolution of SO 2 and NO x Emissions in China
Using the updated methods and input data for each sector described in the previous
sections, significant improvements in total emission estimates have been made
during the last several decades. As is reasonable, emission estimates differ among
inventories, due to differences in the compilation methods and data used (Li et al.
2017b). Recognizing these differences, we focus here on reviewing the best available knowledge of the emission characteristics of SO 2 and NO x , as well as their
driving forces to the emission changes in China.
2.3.1 Emission Estimates
The long-term emissions of SO 2 and NO x since 2000, derived from various studies,
are shown and compared in Fig. 2.1. The sectoral distributions of these two pollutants are shown in Fig. 2.2. China’s anthropogenic emissions are estimated to have
declined by 62% for SO 2 and 17% for NO x since 2010. Most of these emission
reductions have been achieved since 2013 when the Clean Air Action was enacted
and implemented. SO 2 and NO x are the only air pollutants that were incorporated
into national economic and social development plans with emission reduction targets
in China. The 12th Five-Year Plan required the total national emissions of SO 2 and
NO x to be cut by 8% and 10% from 2011 to 2015, respectively, while the actual
reductions were much larger than planned due to the more stringent pollution control
requirements implemented after 2013. Given that China’s economy is growing
rapidly, China’s emissions are decoupling from population, economic, and energy
consumption growth (Zheng et al. 2018). China’s gross domestic product grew by
7.6% per year from 2010 and achieved 67% growth by 2017; however, China’s
emissions flattened out from 2010 to 2013 followed by a significant decrease after
2013, according to the MEIC estimates.
18
Q. Zhang et al.