Assessing the risk of toxic metals contamination and phytoremediation potential of mangrove in three coastal sites along the Red Sea

Abstract

Assessing toxic metals (TMs) contamination and phytoremediation potentiality in coastal mangrove lagoons is needed for applying sustainable management of this ecosystem. Consequently, here we determined the pseudo-total content of TMs in the sediments and mangrove plants (leaves, stems, aerial roots, and fine roots) collected from Al-Shuaiba, Yanbu, and Jeddah lagoons, along the coast of Red Sea. The contamination degree was assessed using different indices and the potentiality of mangroves for TMs phytoremediation was determined. The average total metals content (mg kg−1) in the sediments ranged from 1806 to 9580 for Fe, 65 to 195 for Mn, 3.9 to 25.9 for Cu, 5.5 to 16.4 for Zn, 0.09 to 0.42 for Cd, 8.9 to 20.9 for Cr, 32.8 to 37.9 for Ni, and from 0.69 to 6.7 for Pb. The sediments of Yanbu site contained the highest content of all metals (except for Cu), while Al-Shuaiba sediments contained the lowest values. The contamination factor (CF) showed that the sediments of Yanbu and Jeddah suffer from high and moderate contamination degree of Cd. These sites suffer from moderate grade of Ni contamination. The CF values of Fe, Mn, Cr, Cu, and Zn in the three sites were lower than unity, which show low contamination degree. Iron, Cr, Cu, Ni, Pb, and Zn were concentrated in the fine roots, while Cd was concentrated in the stems. Mangrove plants at Yanbu site contained significantly higher content of all metals than the grown plants in Jeddah and Al-Shuaiba sites, which can be explained by the high metal content in the sediments and the anthropogenic metal sources such as the petrochemical industries, and the industrial and municipal wastewater discharged into this site. Sediment-to-plant transfer coefficients values were higher than unity, which indicate that the mangrove plants have the potential to accumulate the metals. The results highlight a potential risk at Yanbu and Jeddah sites and may help for applying sustainable trials for phyto-management of these lagoons.