Abstract
Abstract. We use a chemical transport model to examine the change of sulfate-nitrate-ammonium (SNA) aerosols over China due to anthropogenic emission changes of their precursors (SO2, NOx and NH3) from 2000 to 2015. From 2000 to 2006, annual mean SNA concentrations increased by about 60% over China as a result of the 60% and 80% increases in SO2 and NOx emissions. During this period, sulfate is the dominant component of SNA over South China (SC) and Sichuan Basin (SCB), while nitrate and sulfate contribute equally over North China (NC). Based on emission reduction targets in the 12th (2011–2015) Five-Year Plan (FYP), China's total SO2 and NOx emissions are projected to change by −16% and +16% from 2006 to 2015, respectively. The amount of NH3 emissions in 2015 is uncertain, given the lack of sufficient information on the past and present levels of NH3 emissions in China. With no change in NH3 emissions, SNA mass concentrations in 2015 will decrease over SCB and SC compared to their 2006 levels, but increase over NC where the magnitude of nitrate increase exceeds that of sulfate reduction. This suggests that the SO2 emission reduction target set by the 12th FYP, although effective in reducing SNA over SC and SCB, will not be successful over NC, for which NOx emission control needs to be strengthened. If NH3 emissions are allowed to keep their recent growth rate and increase by +16% from 2006 to 2015, the benefit of SO2 reduction will be completely offset over all of China due to the significant increase of nitrate, demonstrating the critical role of NH3 in regulating nitrate. The effective strategy to control SNA and hence PM2.5 pollution over China should thus be based on improving understanding of current NH3 emissions and putting more emphasis on controlling NH3 emissions in the future.
Highlights
Systems dominant component of SNA over South China (SC) and Sichuan Basin (SCB), while nitrate and sulfate contribute Sulfate, nitrate and ammonium are the over North China (NC)
In the present-day case (2006), sulfate is the dominant component of SNA over SC and SCB, while nitrate and sulfate contribute over NC
The changes in ground-level mass concentrations and composition of SNA aerosols over China from 2000 to 2015 are simulated using the nested-grid Goddard Earth Observing System (GEOS)-Chem model, based on anthropogenic emission changes of SO2, NOx, and NH3 over the past and in the future driven by emissions control targets in the 11th and 12th Five-Year Plan (FYP)
Summary
Methods and Data Systems dominant component of SNA over South China (SC) and Sichuan Basin (SCB), while nitrate and sulfate contribute Sulfate, nitrate and ammonium (simplified as SNA) are the over North China (NC). In light of the significant impact of SNA aerosols on public health and climate, it is important to understand the extent of SNA concentration changes in response to past and future changes of SO2, NOx and NH3 emissions in China and to evaluate the effectiveness of currently available emission control policies. Previous studies have explored the response of SNA to precursor emission changes (Pinder and Adams, 2007; Tsimpidi and Karydis, 2007, 2008) They found that composite SNA levels did not respond linearly to SO2 or NOx emission changes, with NH3 playing an important role in determining total SNA concentrations.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
