Study of Heavy Metals contamination in Mangrove Sediments of the Red Sea Coast of Yemen from Al-Salif to Bab-el-Mandeb Strait

This research aimed to estimate the concentration of Pb, Cd, Cr, Ni, Co, Cu, Zn, Mn, Mg and Fe in the sediments of mangrove habitats located in the Yemeni from Al-Salif to Bab-el-Mandeb Strait. Samples were collected seasonally at five locations: Al-Salif, Al-Urj, Al-Hodeidah, Yakhtol and Ghorairah, during the months of January, April, August and October 2013, which are chosen to represent the four seasons of a full year. Atomic Absorption Spectroscopy techniques were used to determine heavy metals concentration in the samples, which extracted using Acid digestion methods. The results showed that Heavy metals concentration (µg/g) in mangrove sediments were in the following order: Fe (8,432.0- 15,255.2) > Mg (915.2-2,066.0) > Mn (195.8-528.0) > Zn (27.5-57.2) > Cu (12.3-40.7) > Ni (15.5-34.7) > Cr (15.3-35.6) > Pb (6.2-16.6) > Co (6.2-15.8) > Cd (ND-0.57). The levels of these metals in mangrove sediments were comparable with corresponding in other less polluted area of the world. These metals does not exceed Threshold Effect Level (TEL) and Probable Effect Level (PEL) guidelines, except Cu and Ni, which indicated may be cause low harmful biological effects as proposed by CCME. Cu, Ni, Cd and Mg showed low to moderate polluted status according to USEPA. Relatively high metals concentration at Al-Hodeidah could be due to increasing anthropogenic activities in the vicinity of this site, whereas at Ghorairah may be attributed to the potential contaminants that carried by water currents coming from the Gulf of Aden. Al-Salif and Yakhtol showed no polluted by the studied metals. This might be due to limited influence of anthropogenic activities at these two sites. Elevated metals level during spring and summer may be associated with increasing biological activities, land run off and rainfall during these seasons. Continuous monitoring of these metals in mangrove habitats is recommended to avoid being overcome permissible limits. These findings provide actual heavy metals levels in mangrove sediments being important in designing the long-term management and conservation policies of mangrove ecosystems. In addition, it could represent a database for the future research investigations.