Phytoremediation Characterization of Heavy Metals by Some Native Plants at Anthropogenic Polluted Sites in Jeddah, Saudi Arabia

Many anthropogenic activities have lately resulted in soil adulteration by heavy metals (HMs). The assessment of native plant species that grow in the polluted environments is of great importance for using these plants in phytoremediation techniques. This study was conducted in three industrial regions in Jeddah city, Wadi Marik, Bahra, and Khumrah, to assess the HM contamination level in them. This study also evaluated the phytoremediation ability of nine plant species collected from the studied regions. Soil physicochemical properties of the studied sites were investigated. Nine HMs, aluminum (Al), nickel (Ni), zinc (Zn), cobalt (Co), iron (Fe), lead (Pb), manganese (Mn), chromium (Cr), and barium (Ba), have been evaluated in the collected soil, plant shoots, and root samples. Total thiol concentration in the plant shoots and roots was determined. The phytoremediation indexes, such as bioaccumulation factor (BCF) and translocation factor (TF), were estimated. The results show that the soil of all the explored sites was sandy and slightly alkaline. It was found that Ni, Pb, and Cr were above the international permissible limit in all soil samples. The Wadi Marik region recorded the highest HM concentration compared to the other sites. In the Bahra region, Fe, Zn, Co, and Mn in all collected soil samples were below internationally permissible levels. In Khumrah, the highest concentration of Zn was found in the soil sample collected around F. indica plants, while Fe, Co, and Mn in all collected soil samples were below the international permissible limit. Depending on the BCF calculations, most of the investigated species showed phytostabilization ability for most of the studied HMs. Of them, E. indica, T. nubica, and P. divisum recorded the highest BCF values that ranged from 16.1 to 3.4. The BCF values of the studied HMs reduced in the order of Cr > Zn > Mn > Co > Ba > Fe > Al > Pb. Phytoextration of Co and Cr could be achieved by P. oleracea and F. indica, which showed TF values that reached 6.7 and 6.1, respectively. These plants showed high potential for phytoremediation and can be suggested as protective belts close to the contaminated regions of Jeddah.