Deposition fluxes of trace elements in Western Amazon Basin during 20th century inferred from Illimani ice core, Bolivian Andes
Alexandre
Correia, Institute of Physics, University of Sao Paulo, LGGE, CNRS and Universite Joseph Fourier, acorreia@if.usp.br
(Presenting)
Robert
J
Delmas, LGGE, CNRS and Universite Joseph Fourier, delmas@lgge.obs.ujf-grenoble.fr
Remi
Freydier, UMR5563, LMTG, CNRS and Universite Paul Sabatier, freydier@lmtg.ups-tlse.fr
Jean-Denis
Taupin, LGGE, IRD, jdtaupin@inamhi.gov.ec
Paulo
Artaxo, Institute of Physics, University of Sao Paulo, artaxo@if.usp.br
Bernard
Dupre, UMR5563, LMTG, CNRS and Universite Paul Sabatier, dupre@lmtg.ups-tlse.fr
A 137m ice core drilled in 1999 from the summit of Nevado Illimani (16°37' S, 67°46' W, 6350 m asl, Bolivian Andes) allows the investigation of effective deposition fluxes of trace elements present in aerosols from Western Amazon Basin. The ice core extraction site is downwind from the Amazon Basin. Dating shows the upper 50 m of the ice core correspond to about 80 years of record (1919-1999). Elemental concentrations were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for 45 chemical species (from Li to U) in 744 samples. This yielded a full characterization of the aerosol chemical nature, allowing to retrieve estimates of deposition fluxes over the Andes. During austral winter (dry season) the local aerosol source predominates over other sources, making it difficult to detect the deposition of long-range transported aerosol, such as biomass burning plumes from the Amazon Basin. For phosphorous, a key element participating in biogeochemical cycles in the Amazon Basin, the excess (non-terrigenous) average annual deposition rate between 1919-1969 was about 0.016 x 10-6 kg m-2 yr-1, increasing to about 1.2 x 10-6 kg m-2 yr-1 after 1970. During the 20th century, non-natural deposition fluxes of trace elements linked to anthropogenic emissions, such as nickel, copper, zinc and cadmium, correspond to the major fraction (75%-91%) of total deposition, indicating the influence of anthropogenic sources such as mining activities, for the inventories of these elements.
Submetido por Alexandre Lima Correia em 18-MAR-2004