Heavy Metals in Soils and Vegetation from Wastewater Irrigated Croplands Near Ahmedabad, Gujarat: Risk to Human Health

Abstract

Heavy metal accumulation in soils, and subsequently, in vegetation by long-term wastewater irrigation has a potentially detrimental effect on humans via their transfer along the food chain. In this reconnaissance study the effects of wastewater irrigation on the accumulation of heavy metals (Co, Cr, Cu, Mn, Ni, Pb and Zn) in soils and vegetables from croplands along some ~60 km stretches of Sabarmati River, near Ahmedabad city were assessed. Geochemical factors associated with metals in the soil-water environment seem to regulate more the metal transfer (soil-to-vegetable) than the physiological factors associated with the vegetable’s types. The risk associated with the dietary intake of metal contaminated vegetables was quantified by Hazard Quotient (HQ). HQ was found to be very less sensitive on to the dietary intake pattern (e.g., leafy versus non-leafy vegetables) of the consumers. In contrast to low risk associated with Co, Cu, Ni and Zn with very low HQ values, high risk was found for Pb (HQ of ~6.1±0.6) followed by both Mn and Cr (HQ of ~1.0 ± 0.1). Based on the results on wastewater irrigation in the studied region, we suggest more efficient treatment of wastewater facilities and semi-decadal monitoring of heavy metal in vegetables grown under wastewater irrigated soils.

Keywords

• hazard quotient, heavy metals, risk-assessment, wastewater irrigation