Accumulation of Heavy Metals in Vegetable Food under Wastewater Irrigation
Accumulation of Heavy Metals in Vegetable Food under Wastewater Irrigation
Azra Kalhoro1, Abdul Aziz Mirani2, Fozia Khan Siyal1, Tahira Jatt2*, Abdul Razak Mahar1, Sadia Iram3 and Muhammad Abbas Bhutto4
ABSTRACT
Sewage water contains toxic heavy metals which can be translocated and accumulated in plants and subsequently transferred to human body through the food chain, yet it has become the most commonly used water source for irrigating vegetable crops in peri-urban or urban areas of several countries including in Pakistan. Karachi, the metropolitan city of Pakistan, is the largest industrial and financial hub of the country with an estimated 16 Million population of multilingual, multi-cultural and multi-religious peoples. The current study was conducted to examine the accumulation of six heavy metals (Cr, Ni, Cd, Pb, As and Hg) in cabbage, radish, turnip, cauliflower, and carrot crops, irrigated with sewage water (SW) of peri-urban area of the Karachi. Four treatments were designed, the fresh water (FW) was used as the control (T0), whereas T1, T2 T3 and T4 contained 25, 50, 75 and 100% of SW respectively. The samples analyzed through atomic absorption spectrophotometer using flame atomic absorption techniques revealed that among the five treatments, accumulation of the six metals was found higher with 100% SW, which was decreased with decrease in SW concentration up to 25% SW. The minimum accumulation of the metal was noted with 100% FW (control). Among the five types of vegetables, cabbage and cauliflower revealed a high tendency of accumulating the metals. Hence, in order to avoid exposure of excess heavy metals to human health through vegetables, the cabbage and cauliflower crops may not be grown in the vicinity of Karachi city where the source of irrigation water is only sewage water.
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