Open AccessLong‐term monitoring of atmospheric aerosols in the Amazon Basin: Source identification and apportionment
Author(s) -
Echalar Francisco,
Artaxo Paulo,
Martins José Vanderlei,
Yamasoe Márcia,
Gerab Fábio,
Maenhaut Willy,
Holben Brent
Publication year - 1998
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/98jd01749
Subject(s) - aerosol , environmental science , dry season , mass concentration (chemistry) , gravimetric analysis , environmental chemistry , atmospheric sciences , particle (ecology) , particulates , mineralogy , chemistry , geology , ecology , oceanography , organic chemistry , biology
Continuous sampling of atmospheric aerosols was carried out at two different sites in the Amazon Basin: Cuiabá (16°S, 56°W), since July 1990, and Alta Floresta (09°S, 56°W), since August 1992. Aerosols were collected on polycarbonate filters mounted in stacked filter units (SFU). Particle‐induced X ray emission (PIXE) was used to measure concentrations of up to 26 elements (Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Zr, Au, and Pb). Black carbon (BC) and gravimetric mass analyses were also performed. Inhalable particle ground concentrations showed a marked seasonality, with maxima of more than 100 μg m −3 in the dry season. The high aerosol optical thickness (AOT) values in this period (up to 4.0 at λ = 0.440 μm) indicate that the whole air column has a significant aerosol load. Three main types of aerosol sources were identified: biomass burning, natural biogenic emissions, and soil dust resuspension. During the dry season the fine mode aerosol originated predominantly from biomass burning emissions (they were responsible for about 73% of fine aerosol mass), while the coarse mode was dominated by soil dust particles (50 to 60% of the aerosol mass). Crustal elements exhibited a unimodal coarse mode size distribution, while the pyrogenic elements showed a clear submicrometer mode. Black carbon had a submicrometer mode centered at 0.175 μm. During the wet season, biogenic aerosols were the dominant particle type and also the main source of atmospheric P in the region.