Assessment of Heavy Metals Accumulation in Native Plant Species from Soils Contaminated in Riyadh City, Saudi Arabia

The second industrial area located south of Riyadh City - Saudi Arabia was selected for detailed study as pollution of this area with heavy metals has accelerated dramatically during the last decades. The concentrations of eight metals (Cd, Cr, Co, Cu, Fe, Ni, Pb and Zn) in soils and different plant organs of seven native plant species (Calotropis procera, Citrullus colocynthis, Rhazya stricta, Cassia italic, Phragmite australis, Cyperus laevigatus and Argemone Mexicana) collected from studied area were investigated. The bioaccumulation and transfer of metals from soil to roots and from roots to shoots was evaluated in terms of Bioaccumulation factor (BAF) and translocation factor (TF). The results showed that the concentrations of heavy metals in the soils have the sequence of (Fe > Zn > Cr > Cu > Pb > Ni > Co > Cd) while in plants the trend was (Fe > Zn > Cu > Cr > Ni > Co > Pb > Cd). Generally, leaves of the studied species accumulated less heavy metals than the corresponding roots except for Cd that could be accumulated in all plant organs (leaves, stems and roots). Based on BAFs and TFs values, most of the studied species have potential for phytostabilization and phytoextraction. Calotropis procera is suggested for phytostabiliation of Cu, Cd and Zn whereas Rhazya stricta, Phragmite australis and Cyperus laevigatus for Ni phytostabiliation. Among the plant species screened for Cd, Cu, Ni, Co, Pb and Zn, most of the species were efficient to take up and translocate more than one heavy metal from roots to shoots. According to accumulation capability of the investigated species for most metals, both Phragmite australis and Cyperus laevigatus are found to be the best candidates for biomonitoring and phytoremediation programs of polluted soils. [Khairia M. Al-Qahtani. Assessment of Heavy Metals Accumulation in Native Plant Species from Soils Contaminated in Riyadh City, Saudi Arabia. Life Sci J 2012;9(2):384-392]. (ISSN: 1097-8135). http://www.lifesciencesite.com. 59