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Water Soluble HUmic LIke Substances dans la moyenne et basse troposphère Européenne : caractérisation et évolution passée

Abstract : Atmospheric aerosols play an important role on the radiative properties of the atmosphere. They are also key factors for air quality and public health in polluted areas. As a result of the strong decrease of SO2 emissions over the last three decades, organic aerosol now represents a more important part of atmospheric aerosol. The nature of this organic fraction is complex and until now less than a half of it has been chemically identified. Water Soluble HUmic LIke Substances (HULISWS) are an important contributor to water soluble organic aerosol with a mass fraction ranging from 20 to 50%. The aim of this work is to design a method to measure HULISWS in ice cores. The application of this method to an ice core extracted at the col du Dôme (4250 m, Mont-Blanc massif, France) enables to investigate changes in HULISWS over Europe since 1920. The study of their concentrations and specific absorbance in ice core samples reveals well-marked differences in the sources of HULISWS depending on the season. In winter, HULISWS are primarily emitted by wood burning, their specific absorbance is high and their concentrations are low and remained stable over the 20th century. In summer, HULISWS are producted from biogenic precursors by secondary processes, their specific absorbance is lower and their concentrations higher than in winter. Summer concentrations of HULISWS were stable between 1920 and 1950, and have increased from 1951 to 1970. This recent trend probably results from an increase of volatile organic compounds emissions by the biosphere.
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https://tel.archives-ouvertes.fr/tel-00843021
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Julien Guilhermet. Water Soluble HUmic LIke Substances dans la moyenne et basse troposphère Européenne : caractérisation et évolution passée. Sciences de la Terre. Université de Grenoble, 2012. Français. ⟨NNT : 2012GRENU016⟩. ⟨tel-00843021⟩

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