[Coral-List] Chris Hind, Fertilizing the ocean-disillusionment
eshinn at marine.usf.edu
Fri Oct 12 15:01:29 EDT 2007
Dear Chris, That is not chelated iron being used in the Redlands
agricultural area west of Miami. The area is naturally red because of
a thin accumulation of African Dust that contains iron. That is the
reason it has been such a productive agricultural area in the first
place. You can find the same stuff all over the Caribbean and
Florida Keys. In San Salvador, way out in the eastern Bahamas, it is
called Pineapple loam and without it there would be little
agriculture there. It is also the red soil in potholes all over the
Bahamas (and the Florida Keys) where they are called banana holes.
Pre Columbian pottery on San Salvador was made from African dust
scraped off the lime rock. It contains just enough clay minerals to
be fired and made into pottery. Clay minerals do not occur in the
bahamas unless delivered by the wind. The Florida Keys are covered
with caliche crusts containing African dust and if you drill down
about 30 ft you will find a more extensive layer of red caliche
containing African dust iron. This extensive layer (we call it the Q3
unconformity) accumulated when sea level was about 300 ft below
present and the reef tract was dry land. That layer has also been
correlated with dust layers in Greenland ice cores. (Multer et al
2002). There is a nice display of this caliche put together by Gray
Multer at the Windly Key Fossil Reef State Park.
There are 5 major unconformities capped with red brown caliche
in the first 100ft of limestone below the Florida Keys. The were the
result of previous periods of climate change and they are the
markers that allow us geologists to know where we are when we drill.
The most recent layer on the present surface of the Keys started
forming about 5,000 years ago according to Carbon 14 dating (Robbin
and Stipp 1979) and it is still forming. It even contains elemental
mercury (not published) that predates power plants in the us.
Mercury is mined in North Africa along with phosphate (which also
contains uranium and lead-210) and yes, phosphate and and iron along
with copper and aluminum has been accumulating preferentially in
central Florida Bay but that's another story. It is rewarding to
see so many people on the list agreeing that iron seeding would not
be good for coral reefs and other ecosystems. That is worth knowing
when you realize that 1 billion tons of African dust containing
approximately 5% iron is dispersed in the Atlantic and Caribbean
basin each year. Remember the peak years for dust flux were 1983 and
1984 (Shinn et al 2000)
As for Mt. Trashmore (Black Point landfill) you are correct.
About 20 years ago we installed 4 monitoring wells adjacent to the
land fill. The results are published in a Park Service yearbook. We
found that the landfill " juice" that seeps into the underlying
limestone contains pesticides, plasticizers, and high levels of
ammonium. The Q3 unconformity, mentioned above, is 17 ft below the
surface adjacent to the land fill and it is so dense it prevents
downward passage of land fill "Juice." The juice therefore flows
horizontally in a very permeable layer just above the Q3 unconformity
toward Biscayne Bay. Because of our finding the operators dug a
trench (down to the top of the Q3) around the landfill to contain the
As for the "raping" of gorgonians in the Keys I believe if you
investigate further you will find that they are growing on permitted
areas of rock that was placed there by marine life collectors. In
addition one well known collector grows them under lights under his
home. You might want to check on that before you sound off.
I must admit that a lot of what you say about keys attitudes is
correct. It is a strange and wonderful place first colonized by
people running away from government control and were for many years
more closely allied to Cuba than to the US. World war II changed
that. The anti establishment anti government mind-set is still alive
among the original keys residents. I can say this because I was born
in Key West back when children were propagated there. Gene
Robbin, D. M., and Stipp, J. J., 1979, Depositional rate of laminated
soilstone crusts, Florida Keys. Journal of Sedimentary Petrology, v.
49, pp. 0175-0180.
Shinn, E.A., and Lidz, B.H., (1988), Blackened limestone pebbles:
fire at subaerial unconformities, in Choquette, P.W., and James,
N.P., eds., Paleokarst Systems, Characteristics and Significance:
Springer-Verlag, N.Y., p. 117-131.
Multer, H. G., Gischler, E., Lundberg J., Simmons, K. R., Shinn, E.
A., 2002, Key Largo Limestone Revisited: Pleistocene Shelf-edge
Facies, Florida Keys, USA. FACIES, vol 46 p. 229-272.
Shinn, E.A., Smith, G.W., Prospero, J.M., Betzer, P., Hayes, M.L.
Garrison, V., Barber. R.T., 2000. African Dust and the Demise of
Caribbean Coral Reefs. Geol. Res. Lett. 27, 3129-3032
No Rocks, No Water, No Ecosystem (EAS)
E. A. Shinn, Courtesy Professor
University of South Florida
Marine Science Center (room 204)
140 Seventh Avenue South
St. Petersburg, FL 33701
<eshinn at marine.usf.edu>
Tel 727 553-1158----------------------------------
More information about the Coral-List