Dynamics of Metal Distribution in Cultivated Soil and Vegetables in Vicinity to Industrial Deposition: An Inference to Chemical Contamination of Food Chain

1. Introduction

The accumulation of heavy metals in agricultural soil and plants is of increasing concern due to food safety issues and potential health risk to local inhabitants (khan et al., 2008). Anthropogenic sources of heavy metals are associated with industrial activity and urbanization such as atmospheric deposition, waste disposal, industrial/urban effluents, vehicular exhaust and long term application of wastewater and sewage sludge in agricultural field (Bilos et al., 2001; Cui et al., 2005). Accumulation of heavy metals in consumable vegetables has been well linked with soil heavy metal and irrigation water from long back; atmospheric deposition has now been identified as one of the principal source of heavy metals entering into plants and soil especially around urban-industrial areas (Pandey et al., 2009). Atmospheric heavy metals may deposit by rain and dust, and contributed to elevated metal concentrations in surface layer of soil (Sharma et al., 2008). Heavy metals are extremely persistent in the environment; which in-turn absorbed by plant roots and subsequently mobilized to above ground vegetative parts. Leafy vegetables are known to accumulate sizable amounts of airborne metals (Voutsa et al., 1996; Pandey et al., 2009). Atmospheric metals may be absorbed directly on leafy surface, or entered through stomatal openings and accumulated within plant tissue. Metal accumulation in different plant parts depends on chemical form of metals, their translocation potential, individual species with their stage of maturity (Sinha et al., 2006). Heavy metal contamination in agricultural soil and vegetables through industrial wastewater and atmospheric source are of great concern because of metal translocation in soil-plant system and ultimately to the food chain (khan et al., 2008; Rattan et al., 2005). Thus accumulation of heavy metals in the edible parts of vegetables represents a direct pathway for their incorporation into the human food chain (Florijin et al., 1993); and therefore has drawn the attention of researchers to health risk assessment of population exposed to contaminated foodstuffs.