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SUMMARY:Reconstruction of past atmospheric aerosol load and composition (o
 rganic and inorganic): The case of the European aerosol since 1920 inferre
 d from Alpine ice cores\, and prospective for various polar ice cores.  - 
 Michel Legrand\, Laboratoire de Glaciologie et Géophysique de l’Environ
 nement (LGGE)\, France
DTSTART:20130425T143000Z
DTEND:20130425T153000Z
UID:TALK44757@talks.cam.ac.uk
CONTACT:Dr. Ailsa Benton
DESCRIPTION:Seasonally resolved chemical ice core records available from t
 he Col du Dôme glacier (4250 m elevation\, French Alps)\, are useful in v
 iew to reconstruct past aerosol load of the free European troposphere from
  prior World War II to present. The extended array of inorganic (Na+\, Ca2
 +\, NH4+\, Cl-\, NO3\, and SO42-) and organic (carboxylates\, HCHO\, HUmic
  LIke Substances\, dissolved organic carbon\, water insoluble organic carb
 on\, and black carbon) compounds and fractions already investigated permit
  to examine the overall aerosol composition and its change over the past. 
 It is shown that the atmospheric load of submicron aerosols has been incre
 ased by a factor of 3 from the 1921-1951 to 1971-1988 years\, mainly as a 
 result of a large increase of sulfate (a factor of 5)\, ammonium and water
 -soluble organic aerosol (a factor of 3). It is shown that not only growin
 g anthropogenic emissions of sulfur dioxide and ammonia have caused the en
 hancement of the atmospheric aerosol load but also biogenic emissions prod
 ucing water soluble organic aerosol. This unexpected change of biospheric 
 source of organic aerosol after 1950 needs to be considered and further in
 vestigated in scenarii dealing with climate forcing by atmospheric aerosol
 . \nThis finding on organic aerosol stimulates its study in Greenland and 
 Antarctic snow and ice but dissolved organic carbon data often appear larg
 ely inconsistent and until now no critical review was conducted to underst
 and the causes of these inconsistencies. A more consistent picture is here
  obtained by reviewing available data and\, when needed\, completing the d
 ata set with analyses of selected samples. These Antarctic and Greenland i
 ce core data are briefly discussed with respect to natural (biomass burnin
 g\, vegetation emissions) and anthropogenic sources (fossil fuel combustio
 n) of atmospheric OC aerosol.
LOCATION:room 187\,  British Antarctic Survey\, High Cross\, Cambridge\, C
 B3 0ET
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