Sahara dust

Volz, F. E., Infrared Optical Constants of Ammonium Sulfate, Sahara Dust, Volcanic Pumice, and Flyash, Appl. Opt., 12, 564-568 (1973). 

Natural sources (Sahara dust) contribute significantly to PM10 levels in Lisbon, a factor which can be considered (deducted) in the air quality assessment. 

Fig. 9 Left, satellite photo (infrared, 10.8 pm) of the Sahara dust plume on 28 May 2008, 12 UTC. Source EUMETSAT Meteosat [49]. Right. 72 h backward trajectories for 26 September 2008 showing air mass origin from arid regions north of the Caspian sea (NOAA Hysplit 4.9, data processed by TrajStat reprinted from [7] with permission from Elsevier)...

Contrary to southern Europe where Sahara dust intrusions occur more frequently particle size-resolved analyses show almost no mineral dust in the submicron particle fraction in central and northern Europe (<7ac < 1 pm) [7]. As mentioned before, the mineral dust fraction occasionally can become dominating in case of long-range dust intrusion events. 

Keywords Aerosol, Emission sources, Greece, Mediterranean Basin, Particulate matter, Road dust, Sahara dust, Secondary aerosol, Ship emissions... 

The mineralogical composition of Sahara dust particles shows the predominance of aluminosilicates (clays). Illite is also present in many cases while quartz particles are rare. Scanning Electron Microscopy (SEM) results on dust composition transported over different regions in the Mediterranean Basin have shown that Al-rich clay minerals such as illite and kaolinite are very common in PM10 for Cypms and dominant for Crete. Dust particles are also very rich in calcium which is distributed between calcite, dolomite and sulphates and Ca-Si particles (e.g. smectites) whereas iron oxides are often detected [43]. 

Talbot et al. (1990) and Swap et al. (1995) have shown the chemistry changes associated with long-range transport of aerosols in the Amazon basin. Also, the Amazon region could receive a large influx of trace elements from Sahara dust and tropical Africa (Swap et al. 1995). The magnitude of this flux that can carry essential nutrients to the Amazon basin is still unknown. 

Iron oxides are widespread in nature. They are ubiquitous in soils and roeks, lakes and rivers, on the sea floor, in air (e.g. admixed in aeolian Sahara dust) and in organisms, and they may be responsible for the red-dish-eolored surface of the Mars. Iron oxides are of great significance for many of the properties and processes taking place in ecosystems. 

Gillette, D. A. (1979). Environmental factors affecting dust emission and wind erosion. In Sahara Dust Mobilization, Transport, Deposition (C. Morales, ed.), SCOPE 14, 71-91. 

Prospero, J. M., Nees, R. T., and Uematsu, M. (1987) Deposition rate of particulate and dissolved aluminum derived from Sahara dust in precipitation in Miami, Florida, J. Geophys. Res. 92, 14723-14731. 

Sahara dust (not in the vicinity of a phosphate mine) can contain 0.1-0.3% P2O5 as well as other plant nutrients. Significant quantities of P can be transported to distant soils in this way and it may be particularly important for improving poor soils [48]. 

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