| A. J. Véron Géosciences de l'Environnement University Aix-Marseille III URA CNRS 132, 13397 Marseille 33-91-288719 Internet: veron@frmrs11.bitnet |
T. M. Church College of Marine Studies University of Delaware, Newark, DE 19916 302-831-2558 Omnet T.Church |
Trace metals (Mn, Fe, Ni, Pb, Cd, Cu, Al, Zn and stable lead isotopes) have been analyzed in bulk aerosols collected during the ASTEX MAGE expedition (May 29 to July 30, 1992) which transited between Miami and the Azores in the subtropical North Atlantic. According to lagrangian air mass trajectories, we encountered distinct meteorological regimes including remote oceanic air masses and trade Euro-African Easterlies. Stable lead isotopes confirm these regimes and allow us to better define the continental origin of the aerosol from (1) western Africa and 2) western Europe, as well as to estimate air mass mixing after long range transport over the ocean (in particular, for aerosols originating from North America but advected west into eastern North Atlantic). Aerosol samples display well characterized mineralogical and trace metal content according to these regimes. Trace metal elemental ratios and soil enrichment factors were used to characterize industrial sources of continental aerosols.
According to a principal component analysis, we clearly identify three signals
from coal-oil combustion, non-ferrous metallurgy and steel production. In
spite of long range transport and/or air mass mixing, the combination of
geochemical tracers with mineralogical and physical information (condensation
nucleus concentration, air mass trajectories) allows us to resolve the
continental sources of aerosol-associated trace metals over oceanic region.
These results should be considered when studying cloud nucleation processes in
this area.