[ RadSafe ] Uranium content of airborne dust

Jim Otton jkotton at usgs.gov
Wed Feb 22 10:50:42 CST 2006

There is a far more probable explanation for finding uranium in airborne
dust in the UK that calling upon depleted uranium from Iraq or dust from
uranium mining (very small sources rapidly diluted downwind to background
levels- look at the downwind dust dispersion and deposition data for any
uranium or phosphate mine waste or mill tailings piles).  The uranium
concentration of dust from the Sahara has been measured at 3.6 ppm (Rydell
and Prospero, 1972).  My expectation is that the increase in uranium
concentration is due to an excursion of Sahara dust into the UK, a far
vaster source for uranium.  Massive dust clouds have been observed from
satellite over the Atlantic where they traverse the entire Atlantic from the
Sahara to the Caribbean.  The authors themselves state "Indeed in February
2003 and later in April this airflow carried Saharan desert sand all the way
to the UK (Burt 2003, Simons 2003)".

The deposition and weathering of Saharan dust on uplifted Pleistocene marine
limestone terraces in the Carribean has been implicated in the high uranium
decay product activities of the soils formed on them (Muhs and others, 1990)
and coincidentally the elevated radon potential of these soils.  Guam has
high radon potential on its limestone terranes that is probably derived from
the uranium in Asian dust sources (Otton, 1995).

Jim Otton
U.S. Geological Survey

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