Sulfate-nitrate-ammonium aerosols over China: response to 2000–2015 emission changes of sulfur dioxide, nitrogen oxides, and ammonia 1Ministry of Education Key Laboratory for Earth System Modeling, Center for Earth System Science, Institute for Global Change Studies, Tsinghua University, Beijing, China
05 Mar 2013
2School of Environment, Tsinghua University, Beijing, 100084, China
Received: 06 Aug 2012 – Published in Atmos. Chem. Phys. Discuss.: 17 Sep 2012 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.
Revised: 31 Jan 2013 – Accepted: 10 Feb 2013 – Published: 05 Mar 2013
Citation: Wang, Y., Zhang, Q. Q., He, K., Zhang, Q., and Chai, L.: Sulfate-nitrate-ammonium aerosols over China: response to 2000–2015 emission changes of sulfur dioxide, nitrogen oxides, and ammonia, Atmos. Chem. Phys., 13, 2635-2652, doi:10.5194/acp-13-2635-2013, 2013.