Distribution patterns of mobile heavy metals in the inshore sediments of the Red Sea
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ORIGINAL PAPER
Distribution patterns of mobile heavy metals in the inshore sediments of the Red Sea Mahmoud A. Dar 1 & Mohamed E. A. El-Metwally 1 & Khalid M. I. El-Moselhy 1
Received: 6 May 2014 / Accepted: 6 November 2015 / Published online: 16 March 2016 # Saudi Society for Geosciences 2016
Abstract The mobile forms of heavy metals are the exchangeable phases of these metals that represent the bioavailable toxic hazards in the marine environment. The exchangeable forms of Fe, Zn, Cu, Mn, and Pb were measured using atomic absorption spectrophotometry in the inshore sediments at five locations along the Red Sea coast in areas under natural and anthropogenic discharges. The fine sediment group (FSG) reached the average of 51.29 % representing the controlling and vital factor in the different geochemical processes that occur in seabed sediments. Hamrawin Bay recorded the highest averages of Mn (283.55 μg/g), Zn (99.63 μg/g), and Pb (73.35 μg/g). Abu Dabab recorded the highest average of Fe (1336.41 μg/g), Shalateen exhibited the highest Cu average (35.62 μg/g) and the lowest averages of Mn, Zn, and Pb (50.18, 24.28, and 18.44 μg/g), and Qula’an showed the lowest averages of Fe and Cu (944.61 and 17.39 μg/g). The estimated results indicated that the exchanges from one phase to another were active in all locations due to the continuous reworking processes in the surface sediments. Under the oxic conditions, oxides, hydroxides, and carbonates of Fe, Mn, and Zn were expected to be the dominant metal forms associated with the sand fraction at the different locations. Under the reducing environments (anoxic conditions), sulfide forms of Fe, Pb, Mn, and Cu were associated with fine sediment fractions (very fine sand, silt, and mud) were dominant. Ionic exchanges were active in the near bottom and the interstitial water during the transformation operations from one phase to another at the different locations. The continuity of the forms
* Mahmoud A. Dar [email protected] 1
National Institute of Oceanography and Fisheries, Red Sea, Hurghada, Egypt
transformation in the marine ecosystem at the studied locations provide the favorable environment for benthos growing up. Keywords Mobile forms . Exchangeable phases . Heavy metals . Red Sea . Marine environment
Introduction Marine sediments in the shallow and sheltered areas often act as efficient reservoirs of the different types of heavy metals. This is because various hydrodynamic features of these areas result in long residence times of material deposited there (Duinker 1989). The marine dynamics include winds, currents, waves, and water masses as well as biological activities that affect the state or form of the metals contained in the sediments and, therefore, their mobility and bioavailability (Furness and Rainbow 1990). Within the marine ecosystem, heavy metal contaminants were partitioning between aqueous (pore water, overlying water) and solid phases (sediment, suspended particulate matter, and biota) (Luoma 1983). The enrichment of sediments with heavy metal
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