Agriculture, Forestry and Fisheries 2013; 2(3): 116-125 Published online May 30,2013 (http://www.sciencepublishinggroup.com/j/aff) doi: 10.11648/j.aff.20130203.11 Biomobilization of heavy metals from the sediments affect the bacterial population of Al-Ghadir River (Lebanon) Amale Mcheik 1, 2, *, Mohamad Fakih 1, 2 , Noureddine Bousserrhine 1 , Joumana Toufaily 2, 3 , Evelyne Garnier-Zarli 1 , Taysir Hamieh 2 1 Paris-Est University, Créteil, France 2 Lebanese University, Hadath, Beirut, Lebanon 3 School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164, United States of America Email address: Amale.am@hotmail.com(A. Mcheik), fakih.mohamad@gmail.com(M. Fakih), bousserrhine@u-pec.fr(N. Bousserrhine), joumana.toufaily@ul.edu.lb(J. Toufaily), garnier@u-pec.fr(E. Garnier-Zarli), tayssir.hamieh@ul.edu.lb(H. Taysir) To cite this article: Amale Mcheik, Mohamad Fakih, Noureddine Bousserrhine, Joumana Toufaily, Evelyne Garnier-Zarli, Taysir Hamieh. Biomobilization of Heavy Metals from the Sediments Affect the Bacterial Population of Al-Ghadir River (Lebanon). Agriculture, Forestry and Fisheries. Vol. 2, No. 3, 2013; pp. 116-125.doi: 10.11648/j.aff.20130203.11 Abstract: Although there is no doubt about the importance of the bacterial activity on the solubilisation and the distribution of heavy metals in aquatic sediments, hydromorphic soils and ground waters; little is known about the involvement of bacterial dissolution in periodically anaerobic environments like that found in dredged sediments and little is known about the processes and the environmental factors controlling this process.The aim of this paper was to study the effect of the autochthonous bacterial activity on the biodegradation of organic matter and the mobilization of heavy metals in the sediments of Al-Ghadir river (Mount Lebanon). Sediments were incubated under standard anaerobic conditions and enriched with glucose to stimulate and accelerate microbial metabolism. The evolution of carbon metabolism (Organic matter evolved, carbon consumed and organic acids produced) and metals released in batch reactors were followed over time. Under the adopted conditions, analysis of the chemical parameters indicated that the incubated sediments showed a significant release of organic carbon corresponding to bacterial development. Mineral analysis showed an important solubilisation of Fe 2+ and Mn 2+ indicating the presence of Fe- and Mn-reducing bacteria in sediments. Pb, Cd and Cr solubilisation profiles were observed and appeared concomitant to the solubilisation profiles of Fe and Mn indicating that the redox cycle has been well installed and that Pb, Cd and Cr were associated to Fe and Mn oxides. The production of Cu appeared in parallel to the mineralization of the organic matter in the sediment indicating that Cu was associated to this fraction. Zn appeared associated to the sulphide fraction than to the Fe and Mn oxides fraction. Microbiological and genetic analysis showed a decrease and the disappearance of some bacterial strains due to the shift in the culture conditions and the toxicity of the released heavy metals but at the same time the development and the growth of many other populations which showed to be tolerant to the same conditions. Keywords: Mobilization of Heavy Metals, Incubated River Sediments, Fe- and Mn-Reducing Bacteria 1. Introduction The biogeochemical cycle of heavy metals has been greatly accelerated by human activities. Heavy metals enter the ecosystem through both natural and anthropogenic processes. Some soils have been found to have a high background of some trace elements which are toxic to plants and wildlife. Anthropogenic processes include inputs of heavy metals from industrial and municipal effluents, land-fill leaching, non-point source run-off, and atmospheric deposition [1, 2]. When these metals discharge to the aquatic environment, the metal is partitioned between the sediment and the water column phases. Further partitioning of metals occurs within the sediment chemical fractions and metal speciation occurs in water column with different ligands [3, 4]. This process of metal speciation may lead to the self-purification of rivers from metal pollution. Accumulation of these heavy metals in different compartments of the environment, and particularly in the river sediments, and their possible mobilization under environmentally changing conditions induce a perturbation