Mineralogy of Inhalable Particulate Matter (PM10) in the Atmosphere of Beijing, China

The study of mineral components in respirable particles (particulate matter with diameter less than 10 μm, PM10) in ambient air is important in understanding and improving air quality. In this study, PM10 samples were collected in various areas around Beijing during 2002∼2003, including an urban setting, a satellite city and a rural area. The mineralogical composition of these PM10 samples was studied by X-ray diffraction (XRD), environmental scanning electron microscopy / and energy-dispersive X-ray analyzer (ESEM/EDX). The results indicated that mineral composition of PM10 in different seasons and in different region varied significantly. Mineral mass concentration in Beijing PM10 reached the highest percentage in the spring and fell to the lowest level in the autumn. The minerals in the spring PM10 were dominated by clay minerals and quartz, followed by plagioclase, K-feldspar, calcite, dolomite, hematite, pyrite, magnesite, gypsum and laumontite as well as some unidentified materials. Fewer mineral types were collected in summer, however some new components, including K(NH4)Ca(SO4)2·H2O, NH4Cl and As2O3·SO3 were noted to be present, suggesting that atmospheric chemical reaction in Beijing air were more active in summer than in other seasons. Mineral components in Beijing urban air were at a higher percentage with fewer phases than that in satellite city air. In conclusion, there was considerable variation in mineral components in PM10 samples collected in different seasons and areas, which reflects the related air quality of sampling areas.