I think there is some confusion about the term "ventilation rate" as it is
used here. The work that apparently forms the basis for the 250-year
ventilation rate for the GOM discusses it in terms of how long the deep
water in the Gulf stays there before being carried back out into the
Caribbean Sea. If you look at Figure 15 from the linked reference, it shows
that the deepest water exits over the Yucatan Sill at 2040 meters. What
happens to it after that is unclear. The ventilation rate referred to here
is how long it takes the water to make it out of the Gulf, not how long it
would take CO2 from decomposing bales of crop waste to re-enter the
atmosphere. The relatively high oxygen levels at the bottom, around 5 mg/L
could accelerate oxidation of the waste, but over long periods of time it
would probably become buried in sediment and would be in an anoxic
environment, also limiting any transport of CO2 to the surface. So I would
encourage you to research this a little more before giving up on the Gulf of
Mexico.
http://oceanografia.cicese.mx/personal/jochoa/PDFS/Rivas_etal_JPO_2005.pdf
----- Original Message -----
From: "Stuart Strand" <sstr...@u.washington.edu>
To: <agask...@nc.rr.com>; <z...@atmos.umd.edu>; "geoengineering"
<geoengineering@googlegroups.com>; <climateintervent...@googlegroups.com>
Cc: <xbenf...@aol.com>
Sent: Friday, September 10, 2010 12:50
Subject: RE: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz
Center, Washington DC
After our publication it was pointed out to me that the ventilation rate of
the Gulf of Mexico is such that the half life of water there is about 250
years. One of the major advantages of CROPS over terrestrial burial options
is that the biomass carbon separated from the atmosphere by the ocean
thermocline, so that if CO2 is released from the biomass it will not be
released to the atmosphere for 1000 years (the ventilation rate of the world
ocean). Thus we no longer view burial in the GoM as desirable (except
perhaps in hypersaline pools in the western gulf). As it happens the carbon
cost of transport to the Atlantic abyss is not much greater than our
previous estimates.
= Stuart =
Stuart E. Strand
490 Ben Hall IDR Bldg.
Box 355014, Univ. Washington
Seattle, WA 98195
voice 206-543-5350, fax 206-685-9996
skype: stuartestrand
http://faculty.washington.edu/sstrand/
Alvia Gaskill wrote
You might also consider the use of deep ocean disposal as Strand and Benford
did for crop waste. Wood chips can be sluiced and compressed together might
sink without any weights. Of course, this is probably not a good time to be
recommending doing this in the Gulf of Mexico.
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