Abstract
The study of sulfate aerosols has important research significance to atmospheric chemistry and climate change. A diagnostic study on generation mechanism of sulfate aerosol over the PRD region was conducted using sulfate tracking method. Three pollution episodes occurred in March 2012, in which the first two episodes were mostly caused by fine particulate matters and their secondary aerosols were mainly inorganic sulfates, resulting in low visibility. In contrast, the third pollution episode was dominated by coarse particles with relatively greater visibility. The results of sulfate tracking showed that in addition to emission sources and contributions of initial and boundary conditions, sulfate-generating reaction processes were closely correlated with relative humidity. The first two episodes occurred under the influence of southerly warm and wet air flow system with relatively high humidity, in which the conditions were favorable for aqueous reaction processes. The primary type of liquid-phase oxidation was with hydrogen peroxide (H2O2), followed by catalytic oxidation with Fe and Mn and oxidation with ozone (O3), while peroxyacetic acid (PAA) and methylhydroperoxide (MHP) had very small contributions. Meanwhile, the third pollution episode happened during a warming period following passage of a cold front and was influenced by northerly wind system. Consequently, humidity was relatively low, and therefore, contribution of liquid-phase oxidation reactions was weaker while contributions by gas-phase oxidation between S (IV) and hydroxyl radical (OH) became more prominent. In addition, the simulated vertical distribution results showed that the mass concentration of sulfate aerosols decreased with increasing height. For near-surface layers, sulfates were mainly contributed by emission sources, boundary and initial conditions, liquid-phase oxidations with H_2O_2 and catalytic conversions with Fe and Mn; while for upper layers, sulfates were contributed by, in the order of significance, liquid-phase oxidations with H_2O_2, catalytic conversions with Fe and Mn, emission sources and gas-phase oxidations.
Highlights
The rapid urbanization and industrialization in China have caused episodes of complex regional atmospheric pollution in various megalopolises, and problems with aerosol pollution have become more prominent in particular
This paper used sulfate tracking method to analyze the sources of sulfates among secondary aerosols over the Pearl River Delta (PRD) region during March 2012
The results showed that: (1) Three pollution episodes occurred during March 2012, in which the first two episodes were caused mostly by fine particulate matters while the third one mainly caused by coarse particulate matters
Summary
The rapid urbanization and industrialization in China have caused episodes of complex regional atmospheric pollution in various megalopolises, and problems with aerosol pollution have become more prominent in particular. The results of sulfate tracking showed that in addition to emission sources and contributions of initial and boundary conditions, sulfate-generating reaction processes were closely correlated with relative humidity.
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.
