Prof.  Baghdad  OUDDANE
Université de Lille,  France

Title: Behavior of metal contaminants in aquatic system

Abstract:

Trace metals are considered as serious pollutants in our natural environment because of their persistence, toxicity and bioaccumulation effects. Their presence in irregular contents in waters, sediments, suspended particles and soils could reveal the incidence of anthropogenic sources. Intensive exploitation by industrial activities in densely populated areas often results in the introduction of potentially hazardous levels of metals into aquatic ecosystem because of large amounts of wastes discharged from neighbouring mines and/or smelters along the banks. Trace metals tend to be trapped in the aquatic medium and are concentrated in sediments. Their releases into overlaying waters through sediment resuspension or by organism degradation, desorption from in-place sediments primes to an increased bioavailability, and thereby disturb the aquatic ecosystem. The loading of rivers with toxic metals is now of increasing importance because these aquatic reservoirs become more and more sources of drinking water. Our recent studies on anthropogenic metals present in the case of highly populated and greatly industrialized region of Northern France were focused on some sites like the Seine, the Deûle and the Lys rivers system. A focus will be done on mercury contamination in such area; mercury is a toxic element, widely distributed in the environment and is present in the aquatic systems. It exists in a different chemical species with a wide range of properties and its toxicological and ecotoxicological effect are strongly dependent on the chemical form present. Inorganic mercury Hg (II) is the main form of Hg in waters and sediment samples, which can be naturally converted to much more toxic form methylmercury (MeHg) by bacterial activity (SBR). MeHg is accumulated by aquatic organisms and is known to be bio amplified along the food chain, and poses a threat to humans consuming fish. Knowledge of the concentration, transport and speciation of this compound in aquatic ecosystems is needed to predict the potential impact on human and aquatic life. Functionality and the relationship between metal and biogeochemical parameters will be presented and discussed. Various factors control the transformation of mercury species.  Dissolved organic carbon, sulphate, sulphides, pH, temperature, microorganisms are all dependent factors ruling mercury methylation. Methylmercury degradation is photochemically induced in which this mechanism of degradation is mostly dominant at surface waters.  Sulphides, organic matter, fine/coarse fraction, Fe/Mn oxyhydroxides, mercury partition coefficient between aqueous and solid phases and resuspension activities mainly control mercury mobility.  Recent developments in Hg isotopic tracers have provided new experimental tools to measure the reactivity and dynamics of mercury including different transformations (methylation, demethylation, reduction…). Thus, different mechanisms of mercury biogeochemical cycle and rates of Hg transformation can identified. This allows better understanding of the predominating factors regulating mercury transformation and mobility.

Biography:

Baghdad OUDDANE is Full Professor of Environmental and Water Chemistry in University of Lille (France), he has obtained his PhD in 1990 at University of Lille. Lecturer (1992-2003) and Full Professor at University of Lille since 2003. He is responsible of "Water Sciences" Master in University of Lille.  His research activity covers a broad spectrum of environmental studies, speciation of trace metals in natural waters and sediments, biogeochemical processes in aquatic environments (rivers, canals and coastal areas) and water treatment. He has supervised more than 30 PhD students in Water Chemistry, Analytical Chemistry and Water treatment. He has published 153 publications in international journals and more than 180 communications in national and international conferences, co-authors of four books chapter “(two popular science)” with a total citation greater than 2450 (author h-index 29 and RG Score 38.62) . He is evaluator of research project at the French Research Funding Agency (ANR), participation in several thesis committees as examiner or president in French and foreign universities. He is Associate Editor in « Euro-Mediterranean Journal for Environmental Integration » Topic 3. Water Quality (Assessment, Protection & Management) (Editor: Springer) and Associate Editor “Ciencias Marinas” Journal edited by the Universidad Autónoma de Baja California (Mexico). He is Member of editorial comity of « Advances in Chemistry » (Editor : Hindawi Publishing Corp.) and occasional referee for several international environmental journals (Chemosphere, Environmental Science & Technology, Environmental Pollution, Environment International, Water Research,…). He has organized several seminars and International Conference in the field of Water Chemistry and Water Treatment.