[ RadSafe ] Uranium content of airborne dust

[Wesley]

Jim and All,

 

The dust that blows up from dust storms in the Sahara in Africa travels
hundreds or thousands of miles. This was described by Charles Darwin in his
Voyage of the Beagle:

 

Generally the atmosphere is hazy; and this is caused by the falling of
impalpably fine dust, which was found to have slightly injured the
astronomical instruments. The morning before we anchored at Porto Praya, I
collected a little packet of this brown-coloured fine dust, which appeared
to have been filtered from the wind by the gauze of the vane at the
masthead. Mr. Lyell has also given me four packets of dust which fell on a
vessel a few hundred miles northward of these islands. Professor Ehrenberg
[3] finds that this dust consists in great part of infusoria with siliceous
shields, and of the siliceous tissue of plants. In five little packets which
I sent him, he has ascertained no less than sixty-seven different organic
forms! The infusoria, with the exception of two marine species, are all
inhabitants of fresh-water. I have found no less than fifteen different
accounts of dust having fallen on vessels when far out in the Atlantic.

 

Best regards,

Wes

Wesley R. Van Pelt, PhD, CIH, CHP

Wesley R. Van Pelt Associates, Inc.

 

 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf
Of Jim Otton
Sent: Wednesday, February 22, 2006 11:51 AM
To: radsafe at radlab.nl
Subject: [ RadSafe ] Uranium content of airborne dust

 

Radsafers,

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