Pb presented, consistently, the highest values for
retardation factors showing clearly that it is highly
immobilized by these soils.
agricultural use for all heavy metals except Cd at all the sites. Similarly, the mean heavy metal concentrations in soil were below the Indian standards for all heavy metals, but the maximum value of Cd recorded during January was higher than the standard. However, in the edible portion of B. vulgaris, the Cd concentration was higher than the permissible limits of the Indian standard during summer, whereas Pb and Ni concentrations were higher in both summer and winter seasons. Results of linear regression analysis computed to assess the relationship between individual heavy metal concentration in the vegetable samples and in soil showed that Zn in soil had a positive significant relationship with vegetable contamination during winter. Concentrations of Cd, Cu, and Mn in soil and plant showed significant positive relationships only during summer. Concentration of Cr and Pb during winter season and Zn and Ni during summer season showed significant negative relationships between soil and plant contamination. The study concludes that the use of treated and untreated wastewater for irrigation has increased the contamination of Cd, Pb, and Ni in edible portion of vegetables causing potential health risk in the long term from this practice. The study also points to the fact that adherence to standards for heavy metal contamination of soil and irrigation water does not ensure safe food.