Open AccessContribution of Secondary Particles to Wintertime PM 2.5 During 2015–2018 in a Major Urban Area of the Sichuan Basin, Southwest China
Author(s) -
Du X. X.,
Shi G. M.,
Zhao T. L.,
Yang F. M.,
Zheng X. B.,
Zhang Y. J.,
Tan Q. W.
Publication year - 2020
Publication title -
earth and space science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.843
H-Index - 23
ISSN - 2333-5084
DOI - 10.1029/2020ea001194
Subject(s) - environmental science , noon , pollution , morning , air quality index , china , atmospheric sciences , structural basin , air pollution , relative humidity , climatology , particulates , wind speed , diurnal temperature variation , meteorology , geography , geology , chemistry , medicine , ecology , paleontology , archaeology , organic chemistry , biology
A novel method, noted as approximate envelope method (AEM), was developed to estimate the secondary PM 2.5 concentrations based on the air quality monitoring data. This approach made it possible to obtain the long‐term characteristics of the secondary PM 2.5 using only conventional observations. The secondary PM 2.5 concentrations and their variation characteristics under different PM 2.5 pollution levels during wintertime of 2015 to 2018 in Chengdu, a major urban area of Sichuan Basin over Southwest China, were analyzed. The results showed that the secondary PM 2.5 concentrations ranged from 52.3 to 122.8 μg·m −3 and accounted for 56.3%, 63.6%, and 67.4% of the total PM 2.5 in slight, moderate, and heavy pollution status, respectively. Additionally, the concentrations of secondary PM 2.5 increased year by year, while the concentrations of primary PM 2.5 performed significant decreasing trends from 2015 to 2018. The diurnal variations of primary and secondary PM 2.5 presented a significantly unimodal patterns but with maximum at morning and noon, respectively. Specific meteorological conditions such as high (low) relative humidity and temperature (wind speed and air pressure) aggravated the secondary particulate pollution in wintertime of Chengdu, reflecting an influence of regional climate change over the Sichuan Basin of Southwest China on the urban air pollution.