Biomass burning in the Amazon-fertilizer for the mountaineous rain forest in Ecuador.
BACKGROUND
Biomass burning is a source of carbon, sulfur and nitrogen compounds which, along with their photochemically generated reaction products, can be transported over very long distances, even traversing oceans. Chemical analyses of rain and fogwater samples collected in the mountaineous rain forest of south Ecuador show frequent episodes of high sulfate and nitrate concentration, from which annual deposition rates are derived comparable to those found in polluted central Europe. As significant anthropogenic sources are lacking at the research site it is suspected that biomass burning upwind in the Amazon basin is the major source of the enhanced sulfate and nitrate imput.


METHODS
Regular rain and fogwater sampling along an altitude profile between 1800 and 3185 m has been carried out in the Podocarpus National Park close to the Rio SanFrancisco (3 degrees 58'S, 79 degrees 5'W) in southern Ecuador. pH values, electrical conductivity and chemical ion composition were measured at the TUM-WZW using standard methods.


CONCLUSIONS
Results reported cover over one year from March 2002 until May 2003. Annual deposition rates of sulfate were calculated ranging between 4 and 13 kg S/ha year, almost as high as in polluted central Europe. Nitrogen deposition via ammonia (1.5-4.4 kg N/ha year) and nitrate (0.5-0.8 kg N/ha year) was found to be lower but still much higher than to be expected in such pristine natural forest environment. By means of back trajectory analyses it can be shown that most of the enhanced sulfur and nitrogen deposition is most likely due to forest fires far upwind of the ecuadorian sampling site, showing a seasonal variation, with sources predominantly found in the East/North East during January-March (Colombia, Venezuala, Northern Brazil) and East/SouthEast during July-September (Peru, Brazil).


CONCLUSIONS
Our results show that biomass burning in the Amazon basin is the predominant source of sulfur and nitrogen compounds that fertilize the mountaineous rain forest in south Ecuador.


CONCLUSIONS
The mountaineous rain forest in south Ecuador has developed on poor and acid soils, with low nutrient availability. The additional ferilization resulting from anthropogenic biomass burning constitutes a significant disturbance of this ecosystem, its functioning and biodiversity. Thus it is planned to employ isotope analyses for quantifying the pathways. of nitrate and sulfate deposition in these natural forests.
Fabian
Peter
P
Technical University of Munich, TUM Life Science Center Weihenstephan (WZW), Am Hochanger 13, 85354 Freising, Germany. fabian@met.forst.tu-muenchen.de
Kohlpaintner
Michael
M
Rollenbeck
Ruetger
R
D000392:Air Movements; D000393:Air Pollutants / Q000032:analysis*; D000531:Altitude; D001674:Bioelectric Energy Sources; D018533:Biomass; D017753:Ecosystem; D004484:Ecuador; D004784:Environmental Monitoring; D005308:Fertilizers; D017745:Incineration; D009566:Nitrates / Q000032:analysis; D013431:Sulfates / Q000032:analysis
D000393:Air Pollutants; D005308:Fertilizers; D009566:Nitrates; D013431:Sulfates