Document Type : Research Paper
Author
Assistant Professor, Rangeland Research Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran
Abstract
Background and objectives:
Heavy metals are considered one of the most important soil pollutants due to their toxicity and persistence in the environment. Mines are generally one of the polluting sources of natural ecosystems, and the Khaf area is of particular importance as it has many mines, so it is important to identify plants that have the ability to absorb metals from contaminated soils and, as a result, purify the contaminated soils of this region. In this regard, the present research was conducted in order to investigate the phytoremediation potential of Artemisia sieberi, Salsola richteri and Scariola orientalis species in the area of iron mines of Khaf city in Razavi Khorasan province.
Materials and methods: At first, to determine the dominant type of vegetation, all plant species in the region (at distances of 500, 1000 and 3000 meters from the mine) were monitored, and then three species belonging to the dominant type of vegetation in the region were considered in order to determine the amount of heavy elements. In the next step, samples were taken from different parts of the three dominant plant species in the region and the soil around their roots at different distances from the mine in the direction of the prevailing wind in the region. After vegetation and soil sampling, the collected samples were evaluated to determine mentioned metal elements in their leaves, roots and rhizosphere. It is worth mentioning that copper, iron and lead elements were analyzed in 36 plant samples and 36 soil samples. An inductively coupled plasma device was used to measure the amount of metal contamination in the collected samples. Then, in order to evaluate the ability of the selected plants in cleaning the environment from the mentioned metals, several different indicators of plant remediation were investigated.
Results: The results of the research showed that different vegetation have significant differences with each other in terms of different phytoremediation indicators, so that the highest BCF bioconcentration indicators are lead (1.38), iron (1.37) and copper (1.99) and The BAC of lead (1.55), iron (1.72) and copper (1.95) is related to Salsola richteri vegetation, which shows the high cumulative ability of this plant to absorb lead, iron and copper. The highest amount of lead soil pollution index (2.64) was reported in the soil around Artemisia sieberi vegetation, which shows that the amount of lead is higher than its natural amount in the habitat of this species and it is in the state of moderate lead pollution. Also, the highest level of iron contamination is related to the soil around Artemisia sieberi and Scariola orientalis species.
Conclusion: The results showed that the highest and lowest concentrations of shoot metals, root metals and soil metals were observed at distances of 500 and 10000 meters from the mine, respectively. Based on the results of the soil section, it was determined that the average concentration of the studied elements is higher than the concentration values of these elements in global soils. Among these, the high concentration of elements such as copper with the amount of 490 mg/kg, lead with the amount of 343 mg/kg and iron with the amount of 49000 mg/kg is significant. It is worth mentioning that BCF bioconcentration index of lead, iron, and copper metals of Salsola richteri species at a distance of 500 meters are 1.4, 1.5, 1.45, and 1.02, respectively, and the BAC bioconcentration index of lead metals is Iron and copper are equal to 1.7, 1.8, 1.4, and 1.34 respectively at a distance of 500 meters. Therefore, according to the results, Salsola richteri can be used as a suitable vegetation in decontamination of the soil of Khaf mines.
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