Source apportionment and spatial-temporal variations in the metal content of surface dust collected from an industrial area adjoining Delhi, India.

Surface dust collected during three different seasons from Faridabad industrial area adjoining Delhi is studied for different metals, their spatial and temporal variations, and sources. Al, Fe, Mn, Ti, Ca and Mg show limited variations and lower abundances compared to Upper Continental Crust (UCC); Fe shows enrichment and seasonal changes. Cd, V, Co, Ba, Ti, Ni, Cu, Cr and Zn show significant spatial and temporal variations, and enrichments compared to UCC indicate their anthropogenic sources. Seasonal variability could be due to: 1) different types of industries, 2) variations in the emissions, 3) very frequent shifting of small scale industry within the region, and 4) changes in the land use pattern. The sampling sites, according to the geo-accumulation index, are: 1) least polluted for Ca, Mg, Al and Ti except for Ti in winter, 2) least to moderately polluted for Ba, Co and V but season specific, and 3) moderately to extremely polluted for other metals. Average pollution load index of 2.67-2.87 indicates consistently high level of pollution at all sites in all sampling seasons. The sites located in the residential areas near small to medium scale unorganized industry are more polluted compared to sites near large industries suggesting that the small scale unorganized industries causes more pollution. Three dominant sources of metals were identified: 1) mixed industrial, 2) crustal, and 3) vehicular, oil and battery related burnings. The third component related to Ba, Pb, Cd, Zn and Cr, further splits into two components in the pre-monsoon and winter samples. Surface dust, enriched in metals, is likely to cause serious danger to public health. There is an urgent need to make a shift from unorganized to formally organized industry to reduce the metal pollution and protect human health and environment as a whole.