Sequential Extraction and Particle Size Analysis of Heavy Metals in Sediments Dredged from the Deûle Canal, France

The Deûle canal is one of the most polluted canals in northern France. It contains large volumes of polluted sediments. These have to be dredged and characterized before deciding about the technology suitable for their treatment. The sediments are thus subjected to a physico-chemical characterization comprising particle size classification and heavy metals sequential extraction studies. The total metallic concentrations exceed the French standards for several metals such as cadmium, zinc, lead or copper. On average, 92% of the total weight of each metal are present in the particles that are less than 53 m in size. These particles represent about 85% of the suspended matter dry weight. The sequential extraction study reveals that most of the studied metals are strongly linked to the sediments because of their association with the sulfides and with the organic matter.