Chemical characteristics of PM2.5 during dust storms and air pollution events in Chengdu, China--颗粒学报PARTICUOLOGY

Wang, Q., Cao, J., Shen, Z., Tao, J., Xiao, S., Luo, L., He, Q., & Tang, X. (2013). Chemical characteristics of PM2.5 during dust storms and air pollution events in Chengdu, China. Particuology, 11(1), 70–77. https://doi.org/10.1016/j.partic.2012.08.001

Chemical characteristics of PM_2.5 during dust storms and air pollution events in Chengdu, China

Qiyuan Wang ^{a b}, Junji Cao ^{b c *}, Zhenxing Shen ^a, Jun Tao ^d, Shun Xiao ^{b e f}, Lei Luo ^g, Qingyang He ^b, Xinying Tang ^g

a Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
b Key Lab of Aerosol Science & Technology, SKLLQG, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China
c Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China
d South China Institute of Environmental Sciences, SEPA, Guangzhou 510655, China
e Meteorological Bureau of Baoji Municipality, Baoji 721006, China
f Climate Center of Shaanxi Meteorological Bureau, Xi’an 710014, China
g Institute of Plateau Meteorology, CMA, Chengdu, Chengdu 610071, China

10.1016/j.partic.2012.08.001

Volume 11, Issue 1, February 2013, Pages 70-77

Received 23 December 2011, Revised 19 June 2012, Accepted 13 August 2012, Available online 21 December 2012.

E-mail: cao@loess.llqg.ac.cn

Highlights

► Pollution events had much higher PM_2.5 mass than normal days.

► PM_2.5 from haze and fireworks displays was acidic.

► Dust storms and biomass burning particles were alkaline.

► SO₄²⁻/K⁺ and TCA/SO₄²⁻ ratios were the effective indicators for differentiating pollution events.

Abstract

Daily fine particulate (PM_2.5) samples were collected in Chengdu from April 2009 to February 2010 to investigate their chemical profiles during dust storms (DSs) and several types of pollution events, including haze (HDs), biomass burning (BBs), and fireworks displays (FDs). The highest PM_2.5 mass concentrations were found during DSs (283.3 μg/m³), followed by FDs (212.7 μg/m³), HDs (187.3 μg/m³), and BBs (130.1 μg/m³). The concentrations of most elements were elevated during DSs and pollution events, except for BBs. Secondary inorganic ions (NO₃⁻, SO₄²⁻, and NH₄⁺) were enriched during HDs, while PM_2.5 from BBs showed high K⁺ but low SO₄²⁻. FDs caused increases in K⁺ and enrichment in SO₄²⁻. Ca²⁺ was abundant in DS samples. Ion-balance calculations indicated that PM_2.5 from HDs and FDs was more acidic than on normal days, but DS and BB particles were alkaline. The highest organic carbon (OC) concentration was 26.1 μg/m³ during FDs, followed by BBs (23.6 μg/m³), HDs (19.6 μg/m³), and DSs (18.8 μg/m³). In contrast, elemental carbon (EC) concentration was more abundant during HDs (10.6 μg/m³) and FDs (9.5 μg/m³) than during BBs (6.2 μg/m³) and DSs (6.0 μg/m³). The highest OC/EC ratios were obtained during BBs, with the lowest during HDs. SO₄²⁻/K⁺ and TCA/SO₄²⁻ ratios proved to be effective indicators for differentiating pollution events. Mass balance showed that organic matter, SO₄²⁻, and NO₃⁻ were the dominant chemical components during pollution events, while soil dust was dominant during DSs.

Graphical abstract

Keywords

PM_2.5; Chemical species; Pollution events; Mass balance

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