Title: Heavy Metal Concentrations in Cyanobacterial Mats and Underlying Sediments in Some Northern Western Desert Lakes of Egypt
Abstract: Sixteen trace metals were measured for the first time in cyanobacterial mats and its underlying sediment in eight lakes in the Northern Western desert, Egypt.Al, Ba, Cr, Fe, Pb, Mn, Ni, Cu and Zn concentrations in sediments were many times higher than in cyanobacterial mates.Fe, Al, Mn, Cu were the highest trace metals recorded in the lakes.Geo-accumulation and pollution load indices were applied to assess the human impact in lake sediments, whereas the enrichment factor index was applied for both sediment and cyanobacterial mats.The geo-accumulation index indicated that Siwa lakes sediments were unpolluted with most metals, whereas it fluctuated from unpolluted to moderate polluted with Cu and from moderated to extremely polluted with Cd.The pollution load index revealed that the lakes sediments are unpolluted.The enrichment factor index indicated that all Siwa lakes sediments are extremely enriched with Cd, Cu and Se, whereas, they are impoverishment with As, Sb, Ba, Fe, Sn and V. Cyanobacterial biofilms were highly enriched in Maraqi, Sheata and El-Bahrien, whereas the mats were highly impoverishment in Zieton and Temera.The results suggest that the natural geochemical processes may generate the high concentrations of Fe, Al, Mn and Cu in these aquatic primary producers.