Background
Air currents are capable of transporting great quantities of dust particles over long distances; and hitching a ride upon these mineral particles, as well as interspersed among them in the fluidic turmoil of the atmosphere, are a wide variety of fungal spores and other biologically-active materials that can -- and do! -- periodically wreck havoc upon faraway ecosystems (Shin et al., 2000; Wilkening et al., 2000, Prospero, 2001; Griffin et al., 2002).  Hence, it is important to understand the global transport of dust.

What was done
The authors identified source regions of two sets of dust samples collected in the French Alps by (1) analyzing the mineralogical and geochemical composition of the dust particles, including the isotopic composition of the neodymium contained in the minerals, (2) reconstructing airmass backward trajectories from archived meteorological data, including corroboration by satellite imagery, and (3) using a global transport model driven by assimilated meteorology to simulate dust deflation and long-range transport.

What was learned
It was determined that one of the two sets of dust samples originated in North Africa, while the second set originated in East Asia or, "more precisely," as the authors put it, "the Takla-Makan desert of China."  Hence, they say their analysis suggests that "dust particles have traveled more than 20,000 km in about two weeks, and along their journey, crossed China, the North Pacific, North America and then the North Atlantic Ocean."

What it means
In the words of the authors, "such intercontinental and transcontinental transport and the precise distinctions between source areas is important from the viewpoint of understanding the dust itself, but also from that of the heavy metal, fungal, bacterial and viral pollution that may be associated with it."

It is also important to note, in this regard, that elevated levels of atmospheric CO2 can help to reduce dust sources around the world by enabling plants to establish ground cover where it has typically been too dry for them to successfully grow and reproduce in the past, due to lack of sufficient CO2, which tends to enhance the efficiency with which plants utilize water.  Hence, it can be appreciated that the ongoing rise in the air's CO2 content can help to reduce the long-distance transport of several substances that can negatively impact human health, as well as the health of various plant and animal components of indigenous natural ecosystems.

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

Prospero, J.M.  2001.  African dust in America.  Geotimes 46 (11): 24-27.

Shinn, E.A., Smith, G.W., Prospero, J.M., Betzer, P., Hayes, M.L., Garrison, V. and Barber, R.T.  2000.  African dust and the demise of Caribbean coral reefs.  Geophysical Research Letters 27: 3029-3032.

Wilkening, K.E., Barrie, L.A. and Engle, M.  2000.  Trans-Pacific air pollution.  Science 290: 65-67.