Abstract
In this work, PM2.5 and PM10 samples were collected from four functional regions in Chengdu city from Jan. to Feb. in 2010 and 2011. The chemical concentrations of nineteen elements, two water-soluble ions and TC were measured. The results showed that the levels of particulates and their chemical components were relatively higher in 2010 than those in 2011: for PM10, PM (39%), Si (27%), TC (76%), NO3– (16%), SO42– (19%); for PM2.5, PM (33%), Si (11%), TC (67%), NO3– (32%), SO42– (17%). Ternary diagram analysis, enrichment and other statistical methods were employed to study the spatial and temporal variations of the concentrations of PM and their compositions. Moreover, relative changes (%) of concentrations combined with the relative reported data from statistical yearbook and environmental quality reports are discussed to evaluate the effects of pollution control strategies for different functional regions. Finally, back-trajectory and factor-cluster analysis are proposed as an aid for the discussion of the meteorological influences and the possible source categories. The reduction of crustal dust may be attributed from the influence of long-range air transport. All the methods used above resulted in an overall agreement that showed the pollution control strategies were effective in reducing particulate air pollution: the total carbon (TC) reduction, accounting for 40–49% (PM10) and 35–48% (PM2.5), was mostly attributed to the strategy of banning high-emission yellow-tag vehicles, especially in commercial regions; the reduction of SO2 and NOx emissions had an impact on the sulphate (17.03% for PM10 and 15.37% for PM2.5) and nitrate (12.48% for PM10 and 21.58% for PM2.5) decrease. The findings of this study can provide useful information for developing effective control strategies.
Highlights
Atmospheric particulate matter (PM), which has been studied by numerous researchers, is an important air pollutant in many large cities (Zheng et al, 2005; Moorhouse, 2007; Thurston et al, 2011; Niyobuhungiro and Blottnitz, 2013; Tian et al, 2013)
The results showed that the levels of particulates and their chemical components were relatively higher in 2010 than those in 2011: for PM10, PM (39%), Si (27%), total carbon (TC) (76%), NO3– (16%), SO42– (19%); for PM2.5, PM (33%), Si (11%), TC (67%), NO3– (32%), SO42– (17%)
All the methods used above resulted in an overall agreement that showed the pollution control strategies were effective in reducing particulate air pollution: the total carbon (TC) reduction, accounting for 40–49% (PM10) and 35–48% (PM2.5), was mostly attributed to the strategy of banning high-emission yellow-tag vehicles, especially in commercial regions; the reduction of SO2 and NOx emissions had an impact on the sulphate (17.03% for PM10 and 15.37% for PM2.5) and nitrate (12.48% for PM10 and 21.58% for PM2.5) decrease
Summary
Atmospheric particulate matter (PM), which has been studied by numerous researchers, is an important air pollutant in many large cities (Zheng et al, 2005; Moorhouse, 2007; Thurston et al, 2011; Niyobuhungiro and Blottnitz, 2013; Tian et al, 2013). Some studies have focused on the evaluation of policy implementation (O'Ryan, 1996; Gianini et al, 2012; Li et al, 2012) Such studies have shown that pollution control strategies can be effective in decreasing particulate pollution in urban air. Aerosol and Air Quality Research, 14: 1500–1514, 2014 analysed the changes of PM concentrations under the influence of control measures, few studies have examined their chemical characteristics, especially those of sizeresolved PMs. What’s more, the studies about different regions are quite limited. Because urban areas represent an assembly of different land use types and different source categories, investigation of the effectiveness of control strategies for various functional regions is necessary. A detailed description of sampling and chemical analyses was provided in our previous studies (Bi et al, 2006; Wu et al, 2009)
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