Risk assessment of heavy metal accumulation in soil and plant system irrigated with municipal wastewater.

Abstract. Reuse of wastewater for irrigation is a common practice adopted worldwide. Nearly 90% of such activity is done without proper treatment of wastewater. As a result, 10 % of the world population consuming foods produced from such reuse are exposed to a high risk of trace metal accumulation. In addition to human health risk, the lack of proper treatment before reuse may affect the environment polluting soil and groundwater. The study's objective is to evaluate the effect of wastewater irrigation on the transfer of metals from soil to plants and their toxic effect. The soil and plant samples were collected from the wastewater irrigation region, where such practice is done for more than five decades. The Daily Intake level of Metals (DIM) were found in order Cu> Mn> Cr> Sr> Al> Zn> Ba> Ni> Se> Cd> Co> Mo> As representing potential accumulation of these trace elements in human food chain. The BCF (Bioconcentration Factor) of Cu was critical, ranging from 2.5 to 11, and PLI (Pollution Load Index) was found higher in order Cu>Ni>Pb>Se>Zn. The concentration of certain metals (Al, Cu, Mn) was higher in the leaf than in the stem. Among six varieties of plant samples, Alternanthera sessile was found to exhibit good bioaccumulation capacity, followed by Moringa oleifera. The concentration of Cu and Pb was higher than the standards in all the plants.