DETERMINATION OF LEAD (Pb), IRON (Fe) AND MANGANESE (Mn) CONCENTRATION IN SEWAGE WATER AND VEGETABLE LEAF SAMPLES

Abstract

Application of waste water for irrigation purposes has increased over the past years. This waste water contains high amounts of trace elements and heavy metals.Many of these are non-essential and toxic to plants, animals and human beings. The use of polluted water in the immediate surroundings of big cities in Pakistan is a common practice for growing of vegetables. When this water applied for long time in irrigation, these heavy metals may accumulate in soil and that may be toxic to plants and also cause deterioration of soil. The present study revealed that 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 more 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. Leafy vegetables (spinach, cabbage, coriander etc) showed higher concentration in leaves than in fruits. 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 increase in heavy metal accumulation in different plant species and their different parts is not constant and is not in proportion to the increase in heavy metal concentration in soil irrigated with sewage wastewater.