Heavy Metal Pollution in Avicennia marina Mangrove Systems on the Red Sea Coast of Saudi Arabia

The dynamics of eight heavy metals including Chromium (Cr), Manganese (Mn), Iron (Fe), Nickel (Ni), Copper (Cu), Zinc (Zn), Cadmium (Cd) and Lead (Pb) were assessed in two mangrove system on the Red Sea coast including an industrially exposed site at Yanbu city and a minimal exposed site at Shuaiba. Heavy metal concentrations were measured in mangrove tree components, in sediment and in fallen litter via nitric perchloric acid digestion. It was found that mangrove sediments were the main stocks for heavy metals followed by mangrove woods, a minimal amount ( 3.5%) of heavy metals was returned back to the sediment via litterfall out of which, less that 1% was removed away from the mangrove system via tidal activities. In addition, heavy metal concentrations were generally found to be below contamination limits suggesting that these mangrove systems are relatively clean from heavy metal pollution. However, concentrations were always higher in Yanbu (the exposed site) than in Shuaiba (the less exposed site) suggesting the need for future monitoring and assessment.