Environmental Impacts of Heavy Metal Discharges from a Smelter in Deûle-canal Sediments (Northern France): Concentration Levels and Chemical Fractionation

Abstract

Heavy metal pollution in sediments derived from the Deûle canal and sampled at different sites not far from a smelting plant has been examined in the present work in order to identify the sources of these metals and to assess the sediment environmental quality. The total concentrations of lead, zinc, cadmium, thallium, indium and tin in the samples were determined using inductively coupled plasmaatomic emission spectroscopy (ICP-AES). Our investigations have revealed that metal pollution is readily apparent in the studied sediments, with metals contents largely exceeding those measured in the background soils: maximum values are obtained for sediments collected near the industrial zone. The chemical forms of Pb, Zn, Cd, Tl, In and Sn in these sediments have also been studied using a sequential extraction method in order to evaluate their possible mobility, bioavailability and toxicity in this aquatic environment. Overall, the averaged fractionation of Pb and Zn is dominated, in a decreasing order, by the easily reducible, oxidizable and carbonate fractions. The importance of oxidizable phase (which is assumed to be composed mainly of organic matter and sulphides) in the Pb and Zn fractionations has been confirmed by the detection of X-ray diffraction peaks ascribed to galena (PbS) and wurtzite (ZnS) in contaminated sediment samples. Anthropogenic Tl, In, and Cd are mainly retained in Fe-Mn oxides/ hydroxides, whereas anthropogenic Sn predominates in aluminosilicates/clays. We suspect that elevated percentage levels of Pb, Zn, Cd and In in the reducible fraction constitute a particular potential risk to this aquatic environment in case early diagenetic phenomena (that are observed in the sedimentary material) and physical disturbances (that occur in the water column) both take place strongly in the medium.

Metal content and distribution in surface sediments in an industrial region

“…The Pb association to these phases has been reported by several authors e.g. Davidson et al (1994Davidson et al ( , 2006, Kubová et al (2008), Boughriet et al (2007), Li et al (2009), Vymazal et al (2010, Davutluoglu et al (2011), andDundar et al (2012). Pb oxidizable fraction presence may be due to the complex-metal formation with humic substances and/or metal sulfides insoluble in the sediments (Davutluoglu et al 2011).…”

“…The total concentrations of metal in the Sinos River basin sediments were compared with the specific literature: taking the studied background concentrations (Robaina et al 2002), average shale (Turekian and Wedepohl 1961), and other metals levels in rivers around the globe (Irabien and Velasco 1999, Rodrigues and Formoso 2006, Boughriet et al 2007, Li et al 2009, Davutluoglu et al 2011, Hang et al 2009, Rangel et al 2011, Dundar et al 2012.…”

“…In Hang's et al study (2009), which evaluates the influence of electroplating industries, Zn was also extracted preferably in the exchangeable fraction. In the reducible step of the sequential extraction, Zn associated with Fe and Mn oxides, hydroxides and oxyhydroxides, capable of removing this metal from the aqueous phase (Boughriet et al 2007), was also extracted mainly in this step as indicated by studies of Irabien and Velasco (1999), Rodrigues and Formoso (2006) (2012). Besides Zn and S appearance at the same statistical analysis factor, as mentioned above, proves Zn association to the sulfide oxidizable fraction form.…”

“…Besides that, it provides a corresponding certified reference material and gives a method validation and a way of comparing the data generated (López-Sánchez et al 1998, Rauret et al 1999). This technique involves three steps -exchangeable metals associated with carbonates, reducible metals, and oxidizable metals (Quevauviller et al 1996, Rauret 1998, Pueyo et al 2001, Teixeira et al 2003, Rodrigues and Formoso 2006, Boughriet et al 2007, Davutluoglu et al 2011, Passos et al 2011, Dundar et al 2012). …”

Étude de la contamination par les éléments traces métalliques des sédiments cotiers au niveau des points d’évacuation des eaux usées à Dakar (Sénégal)

“…L'objectif de cette étude est de déterminer les profils de concentration en éléments traces métalliques (Cd, Cr, Cu, Co, Ni, Pb et Zn) des sédiments dans des zones présumées être contaminées par les rejets des eaux usées à Dakar et d'évaluer leur qualité. En effet, les sédiments contaminés constituent des sources potentielles de pollution de la colonne d'eau suite à des perturbations physiques (dragage) ou biogéochimiques (BOUGHRIET et al, 2007). Les sédiments ont été prélevés en surface par raclage dans des tubes de 200 mL qui sont remplis au plein.…”