Abstract
Abstract. Heavy regional particulate matter (PM) pollution in China has resulted in an important and urgent need for joint control actions among cities. It is advisable to improve the understanding of the regional background concentration of PM for the development of efficient and effective joint control policies. With the increase of height the influence of source emission on local air quality decreases with altitude, but the characteristics of regional pollution gradually become obvious. A method to estimate regional background PM concentration is proposed in this paper, based on the vertical characteristics of periodic variation in the atmospheric boundary layer structure and particle mass concentration, as well as the vertical distribution of particle size, chemical composition and pollution source apportionment. According to the method, the averaged regional background PM2.5 concentration in July, August and September 2009, being extracted from the original time series in Tianjin, was 40 ± 20, 64 ± 17 and 53 ± 11 μg m−3, respectively.
Highlights
Atmospheric particulate matter (PM) has attracted considerable attention because it has been associated with many urban environmental problems, such as acid precipitation, decreasing visibility and climate change (Zeng and Hopke, 1989; Charlson et al, 1992; Schwartz et al, 1996; Chameides et al, 1999)
The correlation coefficients between 220 m and other heights were obviously low. These results suggest that the influences of local emissions and local meteorological diffusion conditions on PM10 concentrations are weaker at 220 m than at lower levels
Original PM concentration time series measured on the ground reflect a combination of influence from local pollution and regional-scale pollution
Summary
Atmospheric particulate matter (PM) has attracted considerable attention because it has been associated with many urban environmental problems, such as acid precipitation, decreasing visibility and climate change (Zeng and Hopke, 1989; Charlson et al, 1992; Schwartz et al, 1996; Chameides et al, 1999). Influenced by atmospheric dynamics and thermal effects, meteorological variables and pollutant measurements at different heights within the boundary layer could represent different horizontal scales of pollution. The periodic variation in the atmospheric boundary layer structure and PM mass concentrations, as well as the vertical distribution characteristics of particle size, chemical composition and pollution sources, were studied to characterize the regional pollution contribution. On this basis, the height above which there is relatively less influence by local pollution emission can be determined and the regional background PM concentration can be extracted from the observation data and estimated by mathematical methods
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