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

Abstract

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.

Introduction

Emissions from industries, thermal power plants, fossil fuel burning from vehicles and construction activities are major anthropogenic contributors of metals and metalloids in the urban environments (Khlifi and Hamza-Chaffai, 2010). Although soil–crop system is taken as the main path through which humans are affected by the metals present in the environment (Liu et al., 2007, Sharma et al., 2007, Bose et al., 2008, Pandey et al., 2009), urban dust, especially in industrial areas and road sides not used for growing food crops, influences public health to a significant extent (De Miguel et al., 1997, Mielke et al., 1999, Madrid et al., 2002). Dust inhalation and ingestion, and hand mouth interactions are key pathways through which all human beings, particularly children, are exposed to metals and metalloids (Watt et al., 1993, Meyer et al., 1999, Rasmussen et al., 2001). This leads to high metal levels in blood, and affects intelligence and behavior of the affected person as has also been reported by Dietrich et al. (1990) for lead toxicity. The chronic adverse effects of the metals are well established (Khlifi and Hamza-Chaffai, 2010 and more references therein). This phenomenon is more evident in those urban areas, where multiple sources release large amounts of metals into the environment including atmosphere and soil (Nriagu, 1998, Bilos et al., 2001, Li et al., 2001). Liu et al. (2009) have reported high cancer risk (> 1 × 10^− 6) for Cd, Ni, and Cr in workers occupationally exposed to industrial emissions. Therefore, the need for the better understanding of urban dust pollution has been recognized by several researchers (De Kimple and Morel, 2000, Manta et al., 2002) and research has been carried out worldwide (Kelly et al., 1996, Chen et al., 1997, Mielke and Reagan, 1998). The other important aspect of urban dust pollution is that it is not limited in time and space i.e. there is long term influence extended to space with contamination of air, water and soil (Fujiwara et al., 2011 and references therein).

In developing countries like India, there are enormous problems associated with the metal pollution of surface dust due to industrial activities. Faridabad city located adjacent to the national capital city of India, New Delhi, houses many industries like electroplating, metal coating, tire, tractor, power plant, etc. ranging from small to large scale. It is known that metal plating, copper motor burning and rewiring, batteries, metal alloy industries contribute both ferrous and nonferrous metal pollution in the environment, especially in urban dusts (Khlifi and Hamza-Chaffai, 2010). These authors have reviewed the adverse human health effects of ferrous as well as nonferrous metals such as Pb, Ni, Cr, Cd and Zn. The metal pollution in this region has not been looked into, rather there is lack of information on metal pollution in such areas having multiple types and different scales (small to large) of industries. The urban surface dust samples were collected from nearly 20 locations during three seasons i.e. pre-monsoon, post monsoon and winter from Faridabad industrial area and analyzed for different metals. The metal data is interpreted to understand the metal distribution, spatial and temporal variations, and their sources in the surface urban dust samples, and to assess related environmental and health effects in this region.