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| An integrated approach for investigating the size-segregated mass concentration and chemical composition of atmospheric particulate matter |
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Abstract To improve the methodology of measuring the mass concentration and chemical composition of atmospheric particulate matter, size-segregated samples were collected at three sites, i.e., Beijing, Qianyanzhou and Mountain Dinghu, using a 9-stage impactor (Andersen, USA). Mass concentration deviation and membrane choice were discussed based on weighting condition and chemical analysis. Under the constant temperature and humidity (50% RH, 25℃), mass concentrations of PM2.1 gained from the quartz membrane were 20% higher than that of PM2.5 measured by TEOM, due to the high relative humidity. In contrast, this magnitude decreased to 8% under dry condition (10% RH, 25℃), which falls in a reasonable range. Moreover, if the quartz membrane was conditioned in a dryer (10% RH, 25℃) for 72h before weighing to obtain mass concentration, a significantly linear correlation can be found between the mass concentration of weighted PM2.1 sampled using the Andersen impactor and that of PM2.5 measured by TEOM (R2 = 0.89, P<0.05). To improve the mass closure of particles, asynchronous sampling scheme with cellulose membrane and quartz membrane was built. Consequently, a significantly linear correlation between weighted and chemical reconstructed PM2.1 mass concentration (R2 = 0.89, P<0.05) was observed.
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Received: 10 August 2013
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