JWSS - Journal of Water and Soil Science

The present study was conducted to evaluate the ecological risk indices of Zn, Cu, Cd, Pb and Ni in the soils from Urmia region (Ghahramanloo village), as irrigated with treated wastewater. Accordingly, six different soil sites (five soil sites under wastewater irrigation and one soil site under well water irrigation as the control) were selected and sampled (AP horizon, 0-30 cm depth). Soil samples were air dried, passed through a 2-mm sieve, and analysed to determine the chemical properties and the studied heavy metals. The results showed that irrigation with the treated wastewater significantly increased the total elements in the order of Cd (228%)> Zn (118.5%)> Ni (81.5%)> Pb (54.2%)> Cu (23.5%). Nevertheless, with the exception of cadmium, other elements were within the admissible range based on the national and international standards. Ecological risk index (min = 125, max = 152, mean = 140) showed a considerable risk in all studied soils and Cd could be regarded as the major metal affecting the index yield.

In the present study, six soil profiles belonging to five soil types were dug, described and sampled. Soil samples were analyzed for the determination of different physicochemical properties and total and DTPA-extractable iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), lead (Pb), and cadmium (Cd). Considering the variability of pH and calcium carbonate equivalent, the examined soils were alkaline and calcareous. A considerable change in the values of the DTPA fraction of Fe (1.4-25.8 mg/kg), Zn (0.01-3.3 mg/kg), Cu (0.32- 6.2 mg/kg), Mn (1-11.8 mg/kg), Cd (0.05- 0.12 mg/kg) and Pb (0.22- 2.56 mg/kg) as well as in the total fraction of Fe (10.6-20.6 g/kg), Zn (35- 67.5 mg/kg), Cu (9 to 26.40 mg/kg), Mn (262- 588.8 mg/kg), Cd (0.5- 1.75 mg/kg) and Pb (17- 31.3 mg/kg) was observed in  different soils. The content and pattern of both DTPA and total fraction of the metal were varied among the soil types, which could be related to several processes such as the diversity of weathering rate, geomorphologic condition, soil formation process, different physicochemical properties of soils, and the inputs of different agrochemical compounds. The concentration of both DTPA and total fraction of the metal were in the acceptable maximum level in the majority of the soil samples.