[Coral-List] more African dust

[Gene Shinn]

Dear Craig, Yes the dust has been around for quite a while and over 
the last couple of million years has provided great stratigraphic 
markers and indicators of past sea level changes in the limestones of 
the Caribbean. Whether dust was as abundant in the past as it has 
been since the African drought  began in 1970 is debatable. What is 
not debatable is the abundance of agricultural chemicals that were 
not used in Africa before the 1950s. Yes they still use DDT in North 
Africa and there a lot more people and farm animals than in the past. 
Whether there was as much arsenic in earlier dust storms is not 
known. It is now about 20 ppm when it reaches Florida.  And there is 
abundant mercury, PB-210, Cu, Be-7, Iron, Al, to name a few and, over 
200 viable microbes have  been cultured and identified in the dust so 
far.  About 10% are opportunistic human pathogens and 30% are plant 
pathogens.   And yes, most of the mold species that have caused the 
multi-billion dollar mold problem for the insurance industry over the 
past 20 years are abundant in the dust. Could be they were  there all 
the time. It is also possible  that modern construction methods and 
air conditioning are the real causes of the home mold problem, as 
well as increasing asthma throughout the Caribbean.  Nevertheless, it 
is interesting that the increase in household mold parallels  the 
documented increases in dust storms and Atlantic transport of dust 
that began around 1970. The the soil fungus (mold) that causes the 
ongoing sea fan disease was one of the first to be cultured and 
identified in dust reaching the Caribbean. That mystery we think may 
be  solved but the jury is still out regarding other coral species. 
That the die-off of many coral species, including Diadema,  occurred 
during the most intense period of dust transport between 1983 and 
1984 may just be a coincidence? Ongoing research  hopefully will 
resolve the dilemma in the future.  But who is going to fund the 
research? It's not in the interest of most funding agencies because 
no one knows what to do about it if the cause is African dust. 
Research may show dust is not the cause.  Agencies rarely fund 
research that does not produce a positive result. Funding agencies 
have their agendas. They are humans too. In addition, many feel, "if 
you can't fix it why study it?" Does your chamber of commerce really 
want to hear about it? Anyway, I'm sure you get the idea.  Best 
Wishes,  Gene  PS: And thanks to Steve LeGore  and Melissa Keyes who 
clearly understand the problem.
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No Rocks, No Water, No Ecosystem (EAS)
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http://coastal.er.usgs.gov/african_dust/  		                       |
E. A. Shinn
email  eshinn at usgs.gov
USGS Center for Coastal Geology     |
600 4th St. South                   | voice  (727) 803-8747 x3030
St.Petersburg, FL  33701            | fax    (727) 803-2032
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