[Coral-List] more African dust
Gene Shinn
eshinn at usgs.gov
Thu Jul 28 14:17:31 EDT 2005
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.
--
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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