PRESENCE OF HEAVY METAL IN WATER (YAMUNA RIVER), SOIL AND VEGETABLES IN DELHI AND TO EXAMINE THE EFFECT OF PHYTO-ACCUMULATING CAPACITY OF Eichhornia crassipes

Heavy metal consumption for long term have been reported to have harmful impacts like skin damage, dermatitis, Wilson disease, liver damage, kidney damage, risk of cancer, circulatory disorder and decreased body weights. In the present investigation, concentration of 10 heavy metals - arsenic, cadmium, chromium, mercury, manganese, lead, iron, nickel, copper and zinc, in the water samples of River Yamuna across Delhi was analyzed at six sites. The concentration of iron, copper, nickel and manganese was found in all the six sites. Among these four, the concentration of iron was recorded maximum. The concentration of these four heavy metals were observed in the soils of agricultural field near the river bed or near the water source for three sites. Further, the presence of heavy metals in seven vegetables i.e., cabbage, fenugreek, tomato, onion, potato, radish and spinach, grown on these three fields were analyzed. All these four metals were observed in the vegetables indicating a strong correlation between soil contamination and metal content in vegetables. In search of a phyto-accumulating plant to address the problem of heavy metal contamination in water, the efficiency of Eichhornia crassipes was evaluated. Its effect under heavy metal stress was analyzed by measuring membrane damage quantifying electrolyte leakage, change in chlorophyll and proline content. The percentage electrolyte leakage was found maximum when the tissue was exposed to mercury (98%) followed by copper, lead and nickel which ranged from 80-90%. The total chlorophyll content was found to be maximum in the iron treated tissues (1.97 mg/g FW) followed by arsenic, chromium manganese and zinc. In compared to control, proline accumulation was higher in iron (5 μmol/g FW) treated tissues followed by manganese, zinc, chromium and arsenic. In the present investigation, E. crassipes was found to be an excellent accumulator. Under 72 h, it accumulated all the ten heavy metals studied with maximum of iron i.e., 43.27 mg/100 g tissues, followed by zinc, copper, manganese, nickel. Based on our findings, we propose that the dried tissues of E. crassipes can be used in phytoremediation of heavy metal contaminated water.