Comparison between Impacts of Urban Wastewater and Urban Waste Leachate Applications on Accumulation of Heavy Metals in Soil and Barley

Most sewage wastes contain valuable nutrients that could be used to improve soil fertility. A study was carried out to investigate the comparison between impacts of urban wastewater and waste leachate applications on accumulation of iron (Fe), manganese (Mn), zinc (Zn), nickel (Ni) and cadmium (Cd) in soil and barley (Hordeum vulgare L). The experiment consisted of four treatments including soil irrigated with 300 ml of water (control, T1), soil irrigated with 300 ml of wastewater (T2), soil irrigated with 300 ml of 70% (T3) and 90% (T4) waste leachate to water (V/V) ratios. After 40 days, samples were taken for testing. The concentrations of extractable Fe, Mn, Zn, Cd and Ni (ppm) in soil under T2 were 2.27, 2.04, 1.27, 0.063 and 0.382, they (ppm) in soil under T3 were 2.89, 2.25, 1.79, 0.181 and 0.432, and they (ppm) in soil under T4 were 3.74, 3.31, 2.97, 0.261 and 0.601, respectively. In the barley under the treatments, the concentrations of extractable Fe, Mn, Zn, Cd and Ni (ppm) in roots under T2 were 2.011, 0.942, 0.708, 0.012 and 0.015, they (ppm) in roots under T3 were 2.912, 1.323, 0.985, 0.037 and 0.039, and they (ppm) in roots under T4 were 3.241, 1.996, 1.256, 0.068 and 0.093, respectively. The evidence provided by this experiment indicated that urban wastewater and urban waste leachate caused an increase of extractable heavy metals in soil and barley. Waste leachate application had the more significant effect on accumulation of heavy metals in soil and barley than wastewater application.