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PhD Defense

Claire Froger (LSCE)

Title : Sources and temporal and spatial dynamics of trace element and polycyclic aromatic hydrocarbons in the atmosphere - soil - river continuum in a contrasted catchment

Date and time : The 18-10-2018 at 13h30

Type : thèse

Université qui délivre le diplôme : Université Paris-Sud

Location : Bibliothèque du bâtiment 12 du LSCE (campus CNRS, avenue de la Terrasse, Gif-sur-Yvette)
Members of jury :

Bruno Lartiges, Prof., Université de Toulouse (GET), Rapporteur

Emmanuel Naffrechoux, Prof., Université Savoie Mont-Blanc (LCME), Rapporteur

Béatrice Béchet, CR, IFSTTAR (GERS - EE), Examinateur

Damien Calmels, MC, Université Paris Sud (GEOPS), Examinateur

Emmanuelle Montargès-Pelletier, DR, Université de Lorraine (LIEC), Examinateur

Sophie Ayrault, DR, CEA (LSCE, Gif-sur-Yvette), Directrice de thèse

Cécile Quantin, Prof., Université Paris Sud (GEOPS), Co-Directrice de thèse

Johnny Gaspéri, MC, Université Paris Est-Créteil (LEESU), Invité

Summary :

The development of human societies since the 19th century has led to deleterious impacts on the Critical Zone (from atmosphere to river, including biosphere and soils). Despite the decrease of pollutions since the late 1960’s, contaminations remain especially in urban environment, concentrating human activities. To better manage this pollution, it is necessary to understand the dynamics and pathways of contaminants through the atmosphere – soil – river continuum. The goal of this study in thus to evaluate the temporal and spatial variations of two contaminants (polycyclic aromatic hydrocarbons (PAH) and trace elements (TE)) in the Orge River catchment (900 km2, France) being under increasing urban pressure from up to downstream. Several fingerprinting approaches were used to trace sediment dynamics in the river (radionuclides: 7Be, 210Pb, 137Cs), to identify lead sources (lead isotopes) and PAH sources (PAH molecular ratios). The results demonstrated the strong influence of downstream urban areas on the river quality, with an increasing contamination for Cu, Zn, Sb, Pb and PAH in the particulate phase, and for SO42-, Na+, Cl-, Cu, Zn and Pb in the dissolved phase. The sediment fingerprinting using radionuclides revealed a significant input of particles originating from urban areas and transferred through urban runoff, and identified road deposited sediments as the major source of contaminated particles downstream. Source tracking of Pb and PAH confirmed urban runoff as the main pathway of river contamination. In addition, annual and seasonal PAH and TE fluxes were estimated respectively for the atmospheric inputs, and riverine exports and revealed a global accumulation of contaminant over the catchment, already containing a significant stock of pollutants in its soils. Finally, this study highlights the need to integrate the Critical Zone and the potential of coupling multiples tracking approaches to properly evaluate the contaminant dynamics. These results may be used to establish a model of contaminants transfer in urban catchments.

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