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The Sahara as a possible sink for trace gases
Author(s) -
Pierotti David,
Rasmussen L. E.,
Rasmussen R. A.
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i012p01001
Subject(s) - sink (geography) , trace gas , mineral dust , photodissociation , atmospheric sciences , silicate , environmental chemistry , mediterranean sea , environmental science , mediterranean climate , chemistry , aerosol , mineralogy , geology , meteorology , physics , photochemistry , geography , cartography , organic chemistry , archaeology
Recently evidence has been accumulating pointing to the possibility of a sink for atmospheric trace gases in the desert areas of the world, specifically the Sahara. The proposed mechanism involves adsorption of molecules onto silicate surfaces, and photolysis of the adsorbed molecules by long‐wave solar radiation (λ > 300 nm). To obtain data on this possible sink mechanism we took part in flights over East Africa, the Mediterranean Sea, and the Atlantic Ocean. We collected air samples in dust clouds over East Africa, and in non‐dusty air over Africa, the Mediterranean, and the Atlantic. The results of our measurements show that the samples of air collected in the dust clouds have significantly lower concentrations of N 2 O, CCl 4 , and CH 3 CCl 3 , whereas there is no significant difference between the dusty and non‐dusty air samples for CF 2 Cl 2 and CFCl 3 . This is in general agreement with the experimental results, which found that CCl 4 is photolyzed much more rapidly than CFCl 3 and CF 2 Cl 2 . However, the differences in N 2 O, CCl 4 , and CH 3 CCl 3 concentrations between dusty and non‐dusty air samples are relatively small, and the number of samples is insufficient to support any firm conclusions. The most that can be said is that the results of our measurements are consistent with the hypothesis that desert regions may be acting as sinks for a number of atmospheric trace gases, and that further research is clearly needed in this area.