| Abstract: | Particulate matter from the atmosphere over the Atlantic Ocean along the South American and African Continents has been analyzed for organic tracers from natural and biomass burning emissions. The major biomarker compounds characterized are natural products from continental vegetation consisting primarily of epicuticular wax components. For example, n-alkanes ranged from C25 to C35, with an odd carbon number predominance and carbon maxima (Cmax) at 29 or 31. Concentrations of n-alkanes varied from 0.3 to 680 ng/m3. Nevertheless, n-alkanols are the dominant terrestrial tracers in almost all samples (concentrations from 0.1 to 780 ng/m3) and ranged from C22 to C34 with an even carbon number predominance. Despite the major presence of the natural tracers, organic components from biomass burning emissions are also present in the particulate matter. The major tracers from this source are thermal degradation products from the biopolymer cellulose, namely the dianhydromonosaccharide derivatives levoglucosan, galactosan, and mannosan. In general, the concentrations of levoglucosan, the major derivative from this source in all samples, varied from 0.0008 to 0.15 ng/m3 in atmospheric samples collected over the ocean and from 0.04 to 4860 ng/m3 in terrestrial particulate matter, used as reference in this study. Dehydroabietic acid, another marker compound emitted from burning of Gymnosperm fuel, is also detectable in most oceanic samples at concentrations ranging from 0.0001 to 0.4 ng/m3, whereas in terrestrial aerosol particulate matter, this component is present at much higher concentrations (0.23–440 ng/m3). The presence of these tracers in atmospheric particulate matter over the ocean confirms the long-range transport of smoke from biomass burning off the continents. |
