Seasonal Variation of Physical and Chemical Properties in TSP, PM10 and PM2.5 at a Roadside Site in Beijing and Their Influence on Atmospheric Visibility

Yan-Ju Liu,Qing-Yang Liu,Ting-Ting Zhang,Ren-Jian Zhang,Zhen-Quan Sun,Mei-Gen Zhang

doi:10.4209/aaqr.2013.01.0023

Abstract

In Beijing, capital of China, decreasing visibility has become a serious problem on people’s life, thus a hot environmental concern. An urban roadside site in Beijing was chosen to collect 24-h TSP, PM10 and PM2.5 samples for one month each season from June 2009 to March 2010. The PM mass concentrations, and the concentrations of ions, EC, OC and metals in PM10 and PM2.5 were measured, and their correlation with visibility, as well as the influence of weather factors on visibility were studied. The results showed that daily mean concentrations of TSP, PM10 and PM2.5 were 75–1350 µg/m3 (mean 275.8), 29–448 µg/m3 (mean 187) and up to 300 µg/m3 (mean 92.6), with the number of days exceeding the secondary standard (GB3095-2012) representing 33.3%, 59.8% and 51.0%, respectively. All PM concentrations were higher in spring than in other seasons. Obvious seasonal variations were observed for certain ions, OC, EC and metal concentrations in PM10 and PM2.5. Average mean visibility was low (5.64 km), showing better visibility in summer than in other seasons. PM10 and PM2.5 showed stronger negative correlation with visibility giving coefficients of –0.52 and –0.50. Almost all significant correlations were negative and occurred in autumn for visibility with TSP, PM10 and PM2.5, and with ions, EC and OC in both PM10 and PM2.5. The only positive and significant correlation was found between fine OC and visibility. Negative and significant correlations were also observed for visibility with humidity in autumn and winter, and with minimum temperature in all seasons but summer.

Highlights

Airborne particulate matter (PM) is broadly considered as a potent air pollutant in typical urban locations (Khan et al, 2010), especially in most cities of China (Wang et al, 2009), including Beijing
The results showed that daily mean concentrations of total suspended particles (TSP), PM10 and PM2.5 were 75–1350 μg/m3, 29–448 μg/m3 and up to 300 μg/m3, with the number of days exceeding the secondary standard (GB3095-2012) representing 33.3%, 59.8% and 51.0%, respectively
Obvious seasonal variations were observed for certain ions, OC, EC and metal concentrations in PM10 and PM2.5

Summary

Introduction

Airborne particulate matter (PM) is broadly considered as a potent air pollutant in typical urban locations (Khan et al, 2010), especially in most cities of China (Wang et al, 2009), including Beijing. High concentrations of PM have raised great concerns because of its adverse effects on human health and the environment (Raizenne et al, 1996; IPCC, 2001; Gauderman et al, 2004; Pope, 2004; Xiao and Liu, 2004; Cheung et al, 2005; Kampa and Castanas, 2008; Wang et al, 2008). Decreased visibility has an effect on hospital admissions, which significantly associated with elevated death rates in Shanghai (Ge et al, 2011) It reduces crop yields by decreasing photosynthetic radiation, and affect regional climate by changing the radioactive properties of the atmosphere (Seinfeld and Pandis, 1998; Chameides et al, 1999). Significant differences of aerosol optical properties might be affected by aerosol components under distinct weather conditions (Che et al, 2008)

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