Seasonal behaviours in elemental composition of atmospheric aerosols collected in Islamabad, Pakistan

• Published in: Atmospheric research 2010-02, Vol.95 (2), p.210-223
• Main Authors: Shah, Munir H., Shaheen, Nazia
• Format: Article
• Language: English
• Subjects: Aerosols; Antimony; Applied sciences; Atmosphere; Atmospheric pollution; Cadmium; Chromium; Copper; Earth, ocean, space; Enrichment; Exact sciences and technology; External geophysics; Iron; Magnesium; Manganese; Meteorology; Multivariate analysis; Particles and aerosols; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Seasonal variation; Silver; Strontium; Trace element
• ISSN: 0169-8095; 1873-2895
• DOI: 10.1016/j.atmosres.2009.10.001

Seasonal variations and sources of various elements in the atmospheric aerosols of the Islamabad were investigated by analysing 215 total suspended particulate (TSP) samples collected by using high volume air sampler from June 2005 to May 2006. The concentrations of seventeen elements including Ca, Na, Fe, K, Zn, Mg, Cu, Pb, Sb, Sr, Mn, Co, Ni, Cr, Li, Cd and Ag were measured by AAS. All elements measured in the aerosols of Islamabad displayed a strong seasonal variation: average concentrations of Ca, Fe, Zn, Sr and Cr were highest in autumn, while, Na, K, Cu, Pb, Cd and Li mean levels were at maximum during winter. Mean concentrations of Mg, Mn, Ni, and Ag increased considerably during spring, but average Sb and Co peaked in summer. The quartile distributions of all the elements were also significantly diverse during the four seasons. The enrichment factors (EFs) of all elements (with reference to crustal Fe) indicate that Mg, Mn, Ca, Na and K are mainly from soil sources. The anthropogenic sources have a relatively higher contribution to Cu and Co compared with Ni, Cr, Sr and Li. Sb, Ag, Cd, Zn and Pb are predominantly from anthropogenic sources. Although TSP, Ca, Fe, Mg and Mn exhibited strong mutual correlations in all the seasons, the correlation study revealed significant seasonal variation among other trace elements. In addition, the meteorological parameters also revealed appreciably different seasonal correlations for the trace elements. Principal component analysis (PCA), and cluster analysis (CA) indicated that the natural sources contributed about 30% of identified variance of measured elements in all samples and anthropogenic sources contributed about 45%, and these elements can be classified into three categories as follows: Fe, Mn, Mg and Ca represent the natural contribution; Na, K, Zn, Sr, Cr, Ni, Li and Co represent the input of mixed sources of soils and pollution; and Pb, Cd, Cu, Ag and Sb represent the pollution component.