Intercontinental Transport of Dust and Pathogens

© 2002 Eugene S. Takle

Huge dust storms in desert regions are known to launch copious amounts of fine particles into the atmosphere. As much as two billion metric tons are entrained into the atmosphere annually. While this is a natural phenomenon that has existed before humans began modifying the landscape, Griffin et al (2002) point out that there are two aspects of this issue that come under the category of anthropogenic global change. First, human modification of the landscape leading to desertification has enlarged the global area for such events to occur, allowing for larger dust loading in the global atmosphere. Secondly, and perhaps more significantly, herbicides , pesticides, and excreted pharmaceuticals, along with new strains of bacteria, viruses, and fungi now are accompanying these intercontinental transport events. In particular, water drawdown for irrigation around the Aral Sea in Asia and Lake Chad in Africa have exposed substantial areas that have a wide variety of now-dried human wastes. These materials can be spread by global atmospheric circulation patterns to other continents. Enhanced atmospheric loading of dust from the protracted drought in Africa have been linked to increased bacteria, fungi, and crop pathogens deposited in the Caribbean. The 17-fold increase in asthma in Barbados in the last 30 years is suspected to be linked to increases in African dust storms since 1973.

Reference

Griffin, D. W., C. A. Kellogg, V. H. Garrison, and E.A. Shinn, 2002: The global transport of dust. Amer. Sci., 90, 228-235.