The temporal variability of atmospheric deposition in Guadeloupe

• Main Author: Xu, Yangjunjie
• Other Authors: Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Université de Paris, Rémi Losno, Céline Dessert
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2020
• Subjects: Tropical North Atlantic; Guadeloupe; Atmospheric deposition; Saharan dust; Atmospheric aerosol; Compositional analysis; Rare earth elements; Trace elements; Isotopes; Atlantique Nord tropical; Dépôt atmosphérique; Poussières sahariennes; Aérosol atmosphérique; Analyse compositionnelle; Terres rares; Éléments traces; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://tel.archives-ouvertes.fr/tel-03196768; https://tel.archives-ouvertes.fr/tel-03196768/document; https://tel.archives-ouvertes.fr/tel-03196768/file/XU_Yangjunjie_va2.pdf

Atmospheric deposition provides many nutrients to tropical rain-forests and thus contributes to soil preservation. Its importance is particular in the Caribbean area with high rainfall rate. This work carrried out a continuous temporal study of three and a half years on the deposit flux in Guadeloupe of 45 elements (Al, As, Ba, Be, Ca, Cd, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sc, Sb, Se, Sr, Ti, Tl, U, V, Zn and REEs) and one year on their concentration in air. Detailed isotopic analysis of strontium (87Sr/86Sr), neodymium (143Nd/144Nd) and lead (206Pb, 207Pb, 208Pb) was performed on all samples where possible. The compositional analysis using the methods developed by Aitchison and his collaborators was of great help in the interpretation of the results. We have been able to show that the two main sources of at- mospheric deposition in Guadeloupe are trans-Atlantic Saharan dust for elements considered to be crustal such as iron, aluminium, manganese, REEs, and sea salts for the other elements such as magnesium, sodium, sulfur, and part of molybdenum, potassium and zinc. We note a very strong seasonal variability for the Saharan inflows with a peak of deposition between April and September. Analyses of REEs and iso- topes indicate a regional variability of the sources of Saharan dust without being able today to identify them precisely because of the lack of quantitative data in the emission zones. There is a compositional split between the deposit and the aerosol measured at ground level with some anthropogenic enrichment for aerosol. Le dépôt atmosphérique apporte de nombreux nutriments aux forêts tropicales humides et participe ainsi à la préservation des sols. Son importance est particulière dans la zone caraïbe ou la pluviosité est forte. Ce travail a réalisé une étude temporelle continue de trois ans et demi sur le flux de dépôt en Guadeloupe de 45 éléments (Al, As, Ba, Be, Ca, Cd, Cr, Co, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sc, Sb, Se, Sr, Ti, Tl, U, V, Zn et les terres ...