Timbuktu Meets Coral Reefs: Chemical Contaminants In African Dust     Virginia Garrison1, W. Foreman2, M. Majewski3, C. Holmes1, E. Shinn1, R. Smith4 and M. Ranneberger4   1US Geological Survey, St. Petersburg, FL; 2US Geological Survey, Denver, CO; 3US Geological Survey, Sacramento, CA; 4American International School, Bamako, Mali     Every year, hundreds of millions of tons of African dust are transported from the Sahara and Sahel across the Atlantic to the Caribbean, and southeastern U.S.  In the Caribbean, the sky becomes hazy, visibility decreases to a few kilometers, a fine red dust settles on surfaces, and residents complain of respiratory ailments. The fine soil particles have been carried to the Caribbean for thousands of years, however the quantities of dust reaching the Caribbean have increased dramatically since the early 1970s. The quantity of dust transported is the result of global climate systems, geomorphology of source areas, and regional land use practices. Primarily made up of soil particles so small that human lungs cannot expel them (<2.5 µm), the dust may transport a variety of microorganisms and chemicals that hitch-hike on or within the small particles.  We have recently begun a pilot project to test our hypothesis that Sahelian dust air masses transport chemical contaminants (from the burning of biomass and waste, and use of antibiotics, pharmaceuticals, and pesticides in dust source regions) and radioisotopes (from the source regions and produced in stratospheric transport) thousands of kilometers to the Americas, and that those contaminants may be working synergistically to adversely affect coral reef and human health.