PHYTOAVAILABILITY OF HEAVY METALS IN RELATION TO SOIL CHEMICAL PROPERTIES AND HEALTH RISK ASSESSMENT THROUGH MAJOR EXPOSURE PATHWAYS IN A LONG-TERM SEWAGE CONTAMINATED AREAS OF KOLKATA, INDIA

In this study, we aimed to assess the phytoavailability of heavy metals and their relationship with soil properties (pH, org. C) and quantitative human health indices associated with vegetable consumption or direct soil dust inhalation by local inhabitants in the long-term sewage irrigated areas of Kolkata, India. Samples of soils and commonly grown plants along the waste water stream were collected from 16 sites of that area. We found that the phytoavailability was highest for Pb followed by CL>Ni>Zn>Cd. A positive linear relationship between available Cu and Pb with organic carbon content of the soil was observed, while the availability of Cu, Zn and Ni decreased with increasing soil pH. Soil-induced hazard quotient (HQs) values were much lower than vegetable-induced hazard quotient (HQv) which were far below (<1) to cause potential health hazard. However, the HQv values of Pb and Cd for all the tested vegetables were far greater than 1 and in Colocasia it reached to 18.75 and 11.97, respectively, which indicate that the inhabitants consuming such vegetables are prone to potential health risk. Pb was the single most important element causing health risk (contributing up to 60.4%) followed by Cd (up to 36.47%) to the total measured HQv.