Long term measurements of the elemental composition and optical properties of aerosols in Amazonia

Aerosols are being collected and analyzed for trace elements in two sites in Amazonia since January 2008. On eof the site, Manaus is located in a very pristine area in Central Amazonia. The site is nt affected directly by any urban plume for thousands of kilometers. A second site is located in Porto Velho, in a region with heavy land use change and deforestation. Optical properties (light scattering ad absorption) are also being measured in order to study the climatic impact of aerosols. It was observed a clear seasonal pattern for both sites, with higher concentrations in the dry season. But the difference in seasonal concentrations observed for Porto Velho is much larger due to stronger anthropogenic influences. In Manaus during the wet season, very low concentrations of heavy metals, maybe the smallest measured in continental regions are reported. Positive Matrix Factorization (PMF) was used to separate the different aerosol components. In general, for fine and coarse mode and wet and dry season, 3 aerosol components could be observed: 1) Natural biogenic aerosol; 2) biomass burning component; 3) Soil dust both locally and long range transported Sahara dus