JWSS - Journal of Water and Soil Science

Because of the undesirable effects of lead on soil properties and human health, evaluation of its remediation methods seems to be essential. In order to evaluate the effect of humic acid (HA) on the  decontamination of lead (Pb) spiked-soils in the presence of wormwood plant (Artemicia absantium), an experiment was carried out in a completely randomized  block design with three replications. Experiment factors including different concentrations of Pb (Pb(NO₃)₂ in the  solid form) (0, 250, 500 and 1000 mg kg^-1) and levels of HA (0, 100 and 200 mg kg^-1) were considered. At the end of the growing period of plants, some soil and plant properties were measured. According to the results, BR, MBC, root and shoot dry weights, RWC and Fe and Zn concentrations in the shoot were decreased by increasing the soil Pb concentration. So, the mean values of BR and MBC in Pb₁₀₀₀ treatment was 60 and 51.1 percent lower than those of Pb₀, respectively. Pb accumulation in the root and shoot was enhanced as a result of the increase in the soil Pb concentration. The maximum Pb concentration of shoot (37.10 mg kg^-1) and root (38.1 mg kg^-1) was seen in the Pb₁₀₀₀ treatment. Also, the results suggested that humic acid had a positive effect on the shoot of Fe, Zn and Pb concentrations. So, the concentration of these elements in HA₂₀₀ treatment showed an increase 1.25, 1.64 and 1.66 times more than that of HA₀, respectively. Leaf proline amount was increased significantly by elevating the soil Pb concentration; however, application of 200 mg kg^-1 humic acid decreased leaf proline by 54.5 percent, as compared to the control (HA₀). Therefore, humic acid effect on increasing the plant Pb uptake, improving soil biological properties, and increasing availability and dissolution of Pb showed its ability in promoting the phytoremediation efficiency. According to the obtained results of this study, woodwarm plant (Artemicia absantium) is a non-accumulator that could not be used for phytoremediation purposes.

Soil pollution by heavy metals is a serious environmental problem that threatens the human health. The present study was carried out to investigate and detect the contamination of heavy metals of arsenic, copper, lead, zinc and iron due to human and natural activities in the sediment of lake bed and the surface soils of the eastern part of Urmia Province, West Azarbaijan Province. A total of 20 soil samples and surface deposition from the depths of 0 to 30 cm were collected randomly from the studied areas. After preparing the samples, extraction was carried out to determine the concentration of the heavy metals in the soil by using hydrochloric acid and nitric acid, and the total concentration of metals was measured using ICP-OES. The results of the calculation of the contamination factor showed that copper, iron, zinc and lead in the class of low and medium pollution and arsenic in 65.5% of the samples were very high in the class. The high concentrations of copper, lead and zinc contamination in the margin of the city and the contamination of arsenic in the lake bed were observed. The analysis of the contamination factor maps and contamination index with land use and geological map showed that copper, lead and zinc were mostly affected by human activities and arsenic influenced by the maternal materials in the region.