TRACE METAL MOVEMENT BETWEEN THE FLOOD PLAIN AND STREAM BED SEDIMENTS. THE NAHR IBRAHIM RIVER IN LEBANON AS A CASE STUDY

The movement of pollutants, specifically metals, into or out of a surface stream is an important environmental concern. The aim of this study is to determine the interaction between trace metals in the flood plain soils and river bed sediments of a surface stream. The Nahr Ibrahim River is located approximately 20 km north of Beirut and stretches 30 km inland from Mediterranean Sea. The river is constantly flowing due to contributions from springs and groundwater discharge to the river. The majority of the basin is limestone and dolomite with periodic outcrops of sandstone and basalt. Sample sites were chosen based on the geomorphology of the basin to obtain a comprehensive representation of the river as it flows from the spring heads in the Mountain to the Mediterranean Sea. All samples have been analyzed using a modified Tessier sequential extraction method and XRD (x-ray diffraction). Additionally rock samples collected at each site have been analyzed with XRD to determine the geologic contribution to the movement of metals in the system. Based on previous work pertaining to the amount of metals in stream bed sediments, this study will incorporate information from soil, sediment and hydrogeological characterizations of the Nahr Ibrahim River to determine the movement of pollutants into and out of the Nahr Ibrahim River system.