Magnetic particle characterization in the Seine river system: Implications for the determination of natural versus anthropogenic input

International audience[1] This study presents an innovative application of well-established environmental magnetic proxy parameters on fluvial sediments, with the aim to trace geological and human-induced processes in the complex Seine river drainage system in northern France. We seek to identify environmental fingerprints of mechanical and chemical weathering processes, the regional distribution of the suspended material, and changes in the balance of natural input versus anthropogenic pollution. In order to reach these goals, we applied a combination of rock magnetic and advanced scanning electron microscopic techniques on a large number of sediment trap samples. Generally, we observe an increase in magnetic concentration coupled with a coarsening in magnetic grain size downstream of the Seine river system. Furthermore, the dominant magnetomineralogy changes from high-coercivity minerals upstream in more rural areas to magnetite-dominated assemblages downstream. Each river (segment) shows its specific trend line depending on regional initial input, weathering conditions, drainage area, and potential pollution sources. One major outcome of this study is the observed significant correlation between anthropogenic antimony-rich iron oxide particles and the magnetic concentration. This shows the potential of magnetic remanence measurements as proxy parameters for specific heavy metal pollution concentrations. Hence, the environmental magnetic study presented herein serves to identify major trends as well as local particularities and leads to quantitative analyses of the contributions of individual tributaries in the Seine river system. Components: 9513 words, 9 figures, 4 tables

Chapter 15 Magnetic Properties of Soils

Iron-containing minerals, i.e., magnetic minerals, constitute an intimate part of a soil. These can be derived from the parent rock from which the soil developed, or can be formed in situ, or can be deposited from the atmosphere, originating from natural or anthropogenic sources. Recently, measurement of the magnetic properties of soils have found an increased use in detecting pollution, as a substitute of more time-consuming chemical techniques. The current chapter provides a brief background of the basic concepts of magnetism in order to define the parameters that are used in studies of contamination of soils. A detailed discussion is provided about the various classes of magnetic materials together with the methods that are used to measure magnetic parameters. The effects of several factors such as the presence of iron oxides, mineralogy, and grain size on the magnetic parameters are discussed, as well as, the dependence of the soil magnetic susceptibility on parent lithology, climate, oxidation/reduction, organic matter, topography, sediment source, particle size, and time. The relation between soil contamination, by heavy metals and organic pollutants, and the magnetic properties of soils are detailed based on recent scientific findings. Finally, the function of magnetic bacteria in the presence of contaminants and their impact on natural soil remediation as well as the measurement of a soil\u27s magnetic properties is discussed

IDENTIFICATION D'UN DOMAINE DE LIAISON DE L'APOLIPOPROTEINE AI AUX CELLULES D'HEPATOME HUMAIN HEPG 2

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