Comparing the concentrations of heavy metals chromium, copper and nickel in alfalfa irrigated with water and treated wastewater. (Case Study: Birjand)

Today, due to drought and shortage of water, using of unconventional water in agriculture, particularly effluent from municipal wastewater treatment has particular significance. The limiting factors using of wastewaters is heavy metals. The aim of this study was to compare the concentrations of heavy metals Cr, Cu and Ni in the organs of alfalfa under two models of irrigation. Examples of roots, stems and leaves of alfalfa was collected from two regions: 1- irrigated with treated wastewater, and 2- irrigated with well water, to the heavy metal concentrations measured.Dry and ashed samples of alfalfa were digested using concentratednitric acid. Heavy metals (Cr, Cu and Ni) concentration measured using an ICP-OES instrument(PerkinElmer, USA). The highest concentration of heavy metals, were found in roots of alfalfa. Compare this concentrations with critical concentration show that the metals concentration range is not critical, with that exception of the roots of alfalfa irrigated with water that of metal Cr, potential exposure limits have been critical. The t-test results, only for the metal Cr, showed a statistically significant difference between the two types of irrigation. The one-way ANOVA and Tukeys comparison results also indicates that there was a significant difference between the root, stem and leaf of alfalfa in terms of Cr and Ni concentrations, but in terms of the Cu is not the case. Based on these results, irrigation with treated wastewater Birjand in terms of the accumulation of the heavy metal Cr, Cu and Ni, has no adverseeffects on alfalfa.