Atmospheric Mineral Dust and Trace Metals over Urban Environment in Western India during Winter

Received: December 11, 2011
Revised: April 14, 2012
Accepted: April 14, 2012
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2011.12.0237  

Cite this article:
Sudheer, A. and Rengarajan, R. (2012). Atmospheric Mineral Dust and Trace Metals over Urban Environment in Western India during Winter. Aerosol Air Qual. Res. 12: 923-933. https://doi.org/10.4209/aaqr.2011.12.0237

ABSTRACT

Trace metal concentrations in PM_2.5 and PM₁₀ are studied from Ahmedabad, an urban location in western India. During winter, concentrations of Zn, Cd and Pb are in the range of 16.5–290, 0.1–5.4, 28–1023 ng/m³ in PM_2.5 and 38–459, 0.21–8.4, 48–1223 ng/m³ in PM₁₀, respectively. Enrichment Factor (EF) analysis with respect to Al showed significant enrichment of elements like Cd, Pb, Zn and Cu in fine mode particles, suggesting their strong anthropogenic contribution. About 43% of PM₁₀ mass is constituted by mineral dust, and the dominant fraction (~88%) of the same exists in coarse fraction with a characteristic Fe/Al ratio of 0.53. The Ca/Al ratio is ~1.1 in PM₁₀ and ~0.8 in PM_2.5 indicating that aerosol over this region is rich in Ca minerals compared to the average upper continental crust. Positive Matrix Factorization (PMF) analysis using trace metal and major components reveals five sources for PM_2.5 and six for PM₁₀. The PMF results suggest anthropogenic sources contribute ~80% and 40–50% of the PM_2.5 and PM₁₀ mass, respectively. Incineration/industrial emission, biomass burning, vehicular emissions and re-suspended/long range transported dust are the other prominent sources identified in this work. These source contributions exhibit large temporal variations during winter, as the sampling location is influenced by air masses from different source regions.

Keywords: Trace elements; Mineral dust; PM10; PM2.5; Positive Matrix Factorization