An Identification of Heavy metals Resistant Plants and Bacteria in the Surrounding Lands of Shazand, Arak Lead and Zinc Mine, to be used in Phytoremediation



Heavy metals, due to their inhibitive effects on growth and development of plants and microorganisms are among environmental contaminants. An increase in the heavy metals use and application in industry has lead to adverse effects on agricultural production and human health. Phytoremediation is the technology of exploitation of plants for extraction, fixation and detoxification of pollutants. In this research, a study was carried out on the Shazand Lead and Zinc Mine located in Arak, Iran. The heavy metal pollution and transferring capacity from root to aerial organ in the flora of the area were determined and an identification of heavy metal – absorbent indigenous species was made. From the studied species Achillea wilhelmsii carried the highest level of heavy metal in its aerial organs. There was a significant difference (P.<0.01) observed between this species and the others as to the Pb, Zn, and Cd content (110.1, 387.6, 3 mgkg-1 respectively) based upon Dunken’s Test. Nickel content of the root in wheat crop, cultivated in the area around the location of the mine was on average 29.5 mgkg-1 which was the highest among all plants studied. Results indicate that wheat is a suitable plant for phytoremediation and can be effective in absorbing Ni which in fixed in the roots. In a study of the Translocation Factor (TF) of heavy metals in plants, maximum TFs of 5.9, 4.4, and 4.3 were respectively recorded for Pb, Zn and Cd in Aconthophyllum microcephallam, whereas a maximum Ni TF of 3 was recorded for Achillea wilhelmsii. Results obtained also indicate that heavy metals’ level in soils of the area under study is beyond the permissible, for remedy of which proper measures have to be taken. During the course of the study seven species of heavy metal resistant bacteria were isolated from rhizosphere as well as from soil, inoculums of which could be effectively used in phytoremediation of the heavy metal contaminated soils of the area.