Thanks, Alvia, for pointing this out. On second examination of the paper, I was in error in thinking that the deep Gulf of Mexico is ventilated to surface waters. I confused the deep flow with the Yucatan and Loop Currents of the upper water and got the impression that deep waters rose and exited to the Atlantic through the Straits of Florida. That is not correct. As the Rivas paper shows, deep waters from the Gulf exit back through the Yucatan Strait into the Carribean, which is deeper that the GoM, but where it goes from there I am uncertain; the Anegada-Jungfern Passage, perhaps. It looks like I have more homework to do...
= 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/ -----Original Message----- From: Alvia Gaskill [mailto:agask...@nc.rr.com] Sent: Friday, September 10, 2010 12:10 PM To: Stuart Strand; z...@atmos.umd.edu; geoengineering; climateintervent...@googlegroups.com Cc: xbenf...@aol.com Subject: Re: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC 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. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineer...@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
