CHEMICAL SPECIATION OF SOME PARTICULATE ELEMENTS IN THE ENGLISH-CHANNEL, AND IMPACT OF HUMAN ACTIVITIES ON THE MAGNETIC-BEHAVIOR OF SUSPENDED MATTER

Environmental studies necessitate the knowledge of the various charact eristics of suspended matters/sediments to identify predominant contro ls. To address these problems, we have analysed marine particles colle cted in the English Channel by means of several techniques: 1. graphit e-furnace atomic absorption spectroscopy and inductively coupled plasm a atomic emission spectroscopy to determine total chemical composition ; 2. Fe-57 Mossbauer spectroscopy to identify the various types of iro n and their oxidation states; and 3. electron spin resonance spectrosc opy and mass-susceptibility balance to know the magnetic behaviour of particles. We have undertaken the chemical speciation of some particul ate elements (Ca, Al, Fe, Mn, Cu, V, Ti, and Cr) and determined their total concentration in the particles. These elements were chosen becau se of either their use as reference elements (Ca, Al) or their importa nce in biological/environmental processes or their toxicity. Unfortuna tely, it has not been possible: 1. to apply the sequential extraction procedure to suspended matter because its use has yielded approximatel y constant speciation pattern (even for particles collected at sites p resumably perturbated by human activities); and 2. to use Al or Sc for particulate-element normalization because these metals are discharged by local industries. However, the combined use of the above technique s has allowed suspended matter from several marine regions in the Engl ish Channel to be distinguished not only geographically and/or sedimen tologically, but also anthropogenically in polluted zones. In addition , we have used the Random-Walk numerical model to predict the transpor t of suspended matter along the French coast. The impact of polluted s eawaters derived from Boulogne-sur-Mer on the Gris-Nez Cape area has t hus been surveyed and discussed.