Elevated gross alpha background concentrations

[elizabeth_algutifan@wssrap-host.wssrap.com]

     I am an environmental HP at the Weldon Spring Site Remedial Action 
     Project.  My group measures airborne gross alpha concentration as an 
     indicator of environmental impacts from cleanup activities at our site 
     (the site contains isotopes of uranium, radium, and thorium).  Since 
     about the middle of August I've been seeing elevated weekly gross 
     alpha concentrations pretty much across the board, including at the 
     background station which is 12 miles away. (Since our sources are at 
     ground level, we do not expect that anything from our site could get 
     that far.) Results are obtained on a weekly basis, and now we've seen 
     4 weeks in a row with higher than normal readings.  "Elevated" means ~ 
     2.4E-15 uCi/ml vs. a long-term average of 1.2E-15 uCi/ml, or 
     approximately double.  Has anyone else seen this phenomenon, 
     particularly if you are in the Midwest?  We have some theories, all of 
     which are going to be difficult to prove.  One is that the coal-fired 
     plant 15 miles down the river might be affecting our results.  Does 
     anyone have any insight on the effects of coal burning on natural 
     airborne radioactivity levels?
     
     Thanks,
     Elizabeth Algutifan
     Jacobs Engineering Group
     7295 Hwy. 94 S
     St. Charles, MO  63304
     (314) 441-8086, ext. 3514

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