AEROSOL EMISSIONS BY TROPICAL FOREST AND SAVANNA BIOMASS BURNING - CHARACTERISTIC TRACE-ELEMENTS AND FLUXES

Aerosol particles were collected during the dry season in the amazonia n forest and in African and Brazilian savannas. Sampling was performed inside the plumes of vegetation fires and in the local background atm osphere. Samples were analysed for their elemental composition by Part icle Induced X-Ray Emission (PIXE). Enrichment factors relative to the local background were calculated. Savanna fire aerosols are character ised by enrichments in elements like K, P, Cl, Zn, and Br, whereas for est fire emissions are enriched in Si and Ca, The unexpected low potas sium enrichment factor for the forest fins could be due to the prevail ing smoldering conditions, whereas the high values of potassium enrich ment factor during savanna fires could be associated with the predomin ant flaming conditions. This result indicates that potassium may be co nsidered a good tracer of the flaming phase of fires only. Emission fa ctors of P, S, Cl, K, Ca, Mn, Zn, Br and total particulate matter were calculated for African savanna fires. Our estimates of the annual pot assium and zinc emissions by tropical savanna fires indicate that the contribution of this source should be taken into account to understand the biogeochemical cycle of these elements.