Mineralogical characterization of sediments is necessary to identify phases controlling contaminants release in rivers and to select an appropriate remediation technology. A sediment sampling campaign was conducted to characterize the surface sediments of the Richelieu river estuary at Sorel-Tracy (Quebec, Canada). Chemical analysis of sediments revealed the presence of several trace elements (Cr, Cu, Pb, Zn, Ni and Hg) and organic pollutants (PAHs and other petroleum hydrocarbons). The most active geochemical phase is the carbonate phase. The minerals identified by X-ray diffraction are: calcium carbonate, magnesium carbonate, quartz, kaolinite, mica (illite), chlorite, amphibole, smectite, feldspar, plagioclase, apatite, hematite and pyrite. The semi-quantitative mineralogical analysis of two size fractions (<2 µm and <10 µm) shows the predominance of illite and chlorite over kaolinite and smectite. Physillosilicates content of the fraction <2 µm (33.5%) is higher than the fraction <10 µm (28.7%). The Fe(III)-rich chlorites are present in the sediment matrix as trioctahedral chlorites. Sediments with silty clay texture show a more pronounced geochemical weathering than sandy texture. The results of the mineralogical and chemical analysis indicate that the contaminated sediments can be treated and recycled on land.

Keywords: minerals, phyllosilicates, trace metals, river