Stabilization for the secondary species contribution to PM2.5 in the Pearl River Delta (PRD) over the past decade, China: A meta-analysis

• Published in: Atmospheric environment (1994) 2020-12, Vol.242, p.117817, Article 117817
• Main Authors: Yan, Fenghua, Chen, Weihua, Jia, Shiguo, Zhong, Buqing, Yang, Liming, Mao, Jingying, Chang, Ming, Shao, Min, Yuan, Bin, Situ, Shuping, Wang, Xinming, Chen, Duohong, Wang, Xuemei
• Format: Article
• Language: English
• Subjects: Fine particulate matter; Pearl River Delta (PRD); Pollutant emissions; Secondary species
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2020.117817

The fine particulate matter (PM2.5) pollution is one of the atmospheric environmental problems in densely populated areas of China. The secondary species contribution in PM2.5 is extensively studied but the comprehensive analysis on the long-term trend of the secondary species and the main drivers of this trend in the Pearl River Delta (PRD) have not been explored. Therefore, this study aimed to evaluate the long-term temporal variation of PM2.5 and its secondary species contribution in PRD for twenty years from 2000 to 2019. The results of the meta-analysis showed that the annual average concentration of PM2.5 in the PRD was 60.3 ± 16.8 μg/m3 and generally decreased by 3.9 μg/m3 per year from 2004 to 2019. Three significant transitions in secondary species percentage were observed during 2000–2019: first declined in 2000–2005 before rose in 2005–2008 and followed by a stable period in 2008–2019. The percentage of secondary species stabilized at around 80%, of which secondary organic aerosol (SOA) and secondary inorganic aerosol (SIA, including SO42−, NO3−, and NH4+) had identical contributions to PM2.5 over the past decade. SOA was affected by the concentration of total oxidant (OX) and volatile organic compounds (VOCs) emissions. SO42− and SO2 have declined with significant reductions in SO2 emissions. NO3− and NH4+ were positively and negatively correlated with the atmospheric concentration of NO2 and NH3, respectively. In addition to the current efforts on SO2 and NOx controls, further measures are needed to control NH3 and VOCs emissions over a larger area for PRD to effectively improve the air quality. [Display omitted] •Establishing the long-term database (20 years) of PM2.5 and its chemical compositions by a meta-analysis in the PRD.•The trend of secondary species contribution to PM2.5 was stabilized during the last decade in PRD.•The slowdown of OX concentration and VOCs emissions growth contribute to the decrease of SOA.•NO3− and NH4+ in PM2.5 were positively and negatively correlated with their gaseous precursors, respectively.