Trace metal speciation within sediment from the Arabian Gulf

Geochemical fraction of the trace metal species arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn), collected from varying water depths sediments of Qatar Marine Zone from different locations (N= north, C= central, and S=south) of the Arabian sea were determined using five-stages sequential extraction technique. The total concentration of trace elements trend was as following: Fe (35034.55μg/g) > Mn (757.47μg/g) > Ni (111.65μg/g) > Cr (109.35μg/g) > Zn (81.84μg/g) > As (64.28μg/g) > Cu (61.30μg/g) > Co (18.52μg/g) > Pb (13.82μg/g) > Cd (0.38μg/g). The trace elements were extracted in the following order: exchangeable (EXC), bound to carbonate (CA), Fe-Mn oxide bound (FMO), organic matter bound (OM), and residue (RES), to study the mobility and bioavailability of each metal, as these indicate the potential for metal release to the surrounding environment. Data indicate that 23.40% of Pb concentration was extracted in EXC phase, 58% of Cd concentration was concentrated in the CA phase, an elevated amount of Cr was scavenged by Fe-Mn oxide in the FMO phase, OM phase held a wide variety of non-lithogenic source elements following FMO, and about 84% of the Fe was found in the RES fraction. This phase dominated the fractionation profile of the trace elements except for Cd and Mn.