Source terms and source strengths of the carbonaceous aerosol in the tropics |
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| Authors: | Hélène Cachier Patrick Buat-Menard Michel Fontugne Jacques Rancher |
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| Institution: | (1) Laboratoire Mixte CNRS-CEA, Centre des Faibles Radioactivités, avenue de la Terrasse, BP 1, 91190 Gif-sur-Yvette, France;(2) CEA, BP 511, 75752 Paris Cédex 15, France |
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| Abstract: | Atmospheric aerosol samples were collected in the Ivory Coast, primarily at Lamto (6°N, 5°W) between 1979 and 1981. The samples were analysed for total particulate carbon concentration and isotopic composition (13C/12C) by mass spectrometry. Observed concentrations were found high compared to values reported for temperate regions. Fine particulate carbon in the submicrometersize range accounted for 50 to 80% of the reported concentrations. At Lamto, both particulate carbon concentrations and isotopic ratios exhibit a large temporal variability which is shown to reflect the diversity of sources and their seasonal evolution. Natural emissions from the equatorial forest during the wet season, and biomass burning during the dry season, appear to be the major sources. The latter, though active during only a third of the year, is, on an annual basis, the most important source. Based on the data obtained at Lamto, an attempt has been made to estimate the flux of fine particulate carbon emitted from the tropical regions into the global troposphere. This flux, which is of the order of 20×1012 g C/yr, appears to be equivalent to the flux of fine particulate carbon emitted from industrial sources. These results suggest that the tropospheric burden of fine particulate carbon in lowlatitude regions is dominated by the long-range transport of carbonaceous aerosols originating from the Tropics. |
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| Keywords: | Tropospheric aerosols tropical regions particulate carbon organic matter carbon isotopic composition |
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