Heavy metals accumulation in crops and soils irrigated with raw and treated wastewater

ABSTRACT

Application of wastewater effluents with its heavy metals content as originated from the vast array of industrial activity located in Alex. pose a threat on both irrigated land and raised crops with respect to heavy metal accumulation. 2 important crops were selected for this study, corn [Zea mays] as a summer crop and wheat [Triticum aestivum] as a winter crop were grown on lysimeters irrigated with raw, primary, settled, activated sludge, trickling filtered and chemically, aided primary sediment effluent followed by the above mentioned biological treatment were all used as irrigation effluents. Samples of both plants and the surface and subsurface layers of the three tested soils were analyzed for Cd, Cr, Fe, Mn, Ni and Zn contents. The application of different wastewater effluents to the three soils led to heavy metals accumulation in the leaves of both corn and wheat more than in their seeds. Since the green parts of these two crops are used as animal fodder, this will lead to heavy metal accumulation in the animal tissues which is further eaten by humans. The behavior of each metal is discussed with respect to each plant and the three tested soils. The soil surface layer seems to accumulate Cu, Fe, Mb, Pb, and Zn more than the other two soils. Sand soil having high permeability seems to wash down the absorbed heavy metals and lower their content ratios in the soil