Chemical composition of the ambient aerosol in the Sudan Gezira

Measurements of the composition of aerosol in the Sudan Gezira were made in southerly and northerly airstreams during September and October 1973. By using iron as a normalizing element and calculating enrichment factors it is shown that natural dust is the source of most elements. Exceptions are chlorine, bromine, sulphur and nitrogen which appear to have gaseous sources. Substantial concentrations of oxidized nitrogen and sulphur compounds were measured and are probably produced photochemically. Concentrations of sulphur and nitrogen compounds were lower than in Europe but suggest that anthropogenic sources are having equal impact on their respective natural cycles. Finally, comparisons of aerosol in the Sudan and at Harwell show that the natural Sudanese aerosol is potentially basic whereas anthropogenic European aerosol is acid.