Trace metals in the water columns of the Red Sea and the Gulf of Aqaba, Egypt

Seawater samples were collected from the northern Red Sea and the Gulf of Aqaba at different depths during February 1999 and analyzed for iron, zinc, manganese, nickel, copper, cadmium, cobalt and lead to determine the existing concentration of these metals, their distribution patterns and where contamination has occurred. The concentrations of Fe, Zn, Mn, Ni, Cu, Cd, Co, Pb were scattered in the ranges: (0.56-4.44; mean 1.67+/-0.9 mug L-1), (0.13-1.17; mean 0.24+/-0.12 mug L-1), (0.06-0.21; mean 0.13+/-0.03 mug L-1), (0.05-0.52; mean 0.16+/-0.06 mug L-1), (0.07-0.29; mean 0.14+/-0.06 mug L-1), (0.02-0.78; mean 0.49+/-0.14 mug L-1), (0.06-0.29; mean 0.15+/-0.04 mug L-1), and (0.02-0.68; mean 0.31+/-0.13 mug L-1), respectively. The results revealed a small range of variation and regional irregularities. It also indicated significant higher concentrations for Fe, Cd and Pb compared to other metals. Compared to the northern Red Sea, significant higher concentrations for Ni and Cd are measured at the Gulf of Aqaba. Other metals, i.e. Fe, Zn, Mn, Cu, Co, and Pb are not significantly different in both areas indicating no distinct concentration gradients. Except for Pb, the distribution patterns indicated significantly lower concentrations at surface layer in both regions, then increasing to their maximum values at the sub-surface layers which followed by a decrease in deep water. The study indicated also that the mean concentrations of trace metals examined here are much lower than those reported for the Mediterranean Sea and typical of open ocean water.