Biomass burning and implications for the pattern of nitrogen deposition in the Amazon Basin
Luciene
Lorandi
Lara, CENA/USP, luciene@cena.usp.br
(Presenting)
Paulo
Artaxo, IF/USP, artaxo@if.usp.br
Elisabeth
A.
Holland, ACD/NCAR, eholland@ucar.edu
Theotonio
Pauliquevis, IF/USP, theo@if.usp.br
Nitrogen deposition has been measured at Fazenda Nossa Senhora in Rondonia during the SMOCC campaing (Smoke aerosols, clouds, rainfall and climate-aerosols from biomass burning perturb global and regional climate) from September 2002 through November 2002, and in Balbina from March, 2000 through December, 2001. Analysis of NO3-, NH4+ and NO2- were performed by ion chromatography in rainwater samples collected by event in a wet only sampler in these two distinct sites.
In the Amazon region, land use changes have produced a 2 fold increase in nitrogen deposition. This increase is linked to biomass burning emissions, which also drive a shift in the composition of nitrogen deposition from nitrate to an ammonium dominated nitrogen deposition budget. In Balbina, a region that could be considered a pristine area, the annual nitrogen wet deposition is 2.9 kg.N.ha-1.yr-1 and dominated by nitrate. However, in Rondonia which is one of the best examples of how fast Amazonian ecosystems are undergoing anthropogenic changes, the nitrogen wet deposition rate of 5.7 kg.N.ha-1yr-1 is dominated by ammonium and similar to values found in very industrialized regions. The strong positive correlation of nitrogen wet deposition and the number of hot pixels found in Rondonia shows clearly that the changes in the nitrogen deposition pattern are linked to biomass burning emissions and consequently to land-use changes.