Comparative assessment of different heavy metals in urban soil and vegetables irrigated with sewage/industrial waste water

This study was conducted to investigate heavy metals content of sewage water and its impact on soil and their uptake by vegetables irrigated by the sewage/industrial effluent. Twenty five samples each of water, soil, and vegetable leaves and edible vegetable portions were collected from different sites, in Lahore city of Pakistan. Parameters like pH, and electrical conductivity (EC) were also determined The results indicated that soil irrigated by sewage water having tolerable DTPA-extractable metals contents, The concentration of heavy metals in upper layer of soil (0 -15 cm) is higher than the lower layer (15-30 cm). The reason behind is that the upper layer was receiving sewage water permanently while the penetration of sewage water below 15 cm was less. The heavy metal content was above the toxicity level in leafy vegetables grown in the area of Lahore. This study showed that among the different tested plant species, the amount of heavy metals was higher in leaves than fruits. Plants whose fruits grow below the soil showed higher concentration of heavy metals while other showed less concentration whose edible portion was above the ground level. While leafy vegetables (Spinach, Cabbage, Coriander etc) showed higher concentration in leaves than in fruits, indicating that these vegetables should be consumed carefully if produced using the polluted water.