On the issue of using Lair as a vent sealant, I may be wrong, but, I do believe the ice formed would most likely float away. And, a vent would be most likely more of a diffused field of bubble streams as opposed to a central "vent". Also, capping such a vent with even cement will be eventually compromised by the build up of pressure. Finding even a small fraction of the expected release areas would be difficult. Overhead imaging may help in that chore, yet, I personally do not know how a methane release point can be remotely detected.
As far as Oxides of nitrogen/hydroxyl radicals. Yes, NOX is reactive with many GHG. It is also known to produce significant health risks at long distances and acid rain. Here is a short health effects list from Wiki; "Health effects" "NO*x* reacts with ammonia <http://en.wikipedia.org/wiki/Ammonia>, moisture, and other compounds to form nitric acid<http://en.wikipedia.org/wiki/Nitric_acid> vapor and related particles. Small particles can penetrate deeply into sensitive lung tissue and damage it, causing premature death in extreme cases. Inhalation of such particles may cause or worsen respiratory diseases such as emphysema <http://en.wikipedia.org/wiki/Emphysema>, bronchitis<http://en.wikipedia.org/wiki/Bronchitis> it may also aggravate existing heart disease.[7]<http://en.wikipedia.org/wiki/NOx#cite_note-6> NO*x* reacts with volatile organic compounds<http://en.wikipedia.org/wiki/Volatile_organic_compounds> in the presence sunlight to form Ozone <http://en.wikipedia.org/wiki/Ozone>. Ozone can cause adverse effects such as damage to lung tissue and reduction in lung function mostly in susceptible populations (children, elderly, asthmatics). Ozone can be transported by wind currents and cause health impacts far from the original sources. The American Lung Association estimates that nearly 50 percent of United States inhabitants live in counties that are not in ozone compliance.[8]<http://en.wikipedia.org/wiki/NOx#cite_note-7> NO*x* destroys ozone in the stratosphere<http://en.wikipedia.org/wiki/Ozone_layer> .[9] <http://en.wikipedia.org/wiki/NOx#cite_note-NOAA_N2O-8> Ozone in the stratosphere absorbs ultraviolet light<http://en.wikipedia.org/wiki/Ultraviolet_light>, which is potentially damaging to life on earth.[10]<http://en.wikipedia.org/wiki/NOx#cite_note-NASA-9> NO*x* from combustion sources does not reach the stratosphere; instead, NO* x* is formed in the stratosphere from photolysis<http://en.wikipedia.org/wiki/Photolysis> of nitrous oxide <http://en.wikipedia.org/wiki/Nitrous_oxide>.[9]<http://en.wikipedia.org/wiki/NOx#cite_note-NOAA_N2O-8> NO*x* also readily reacts with common organic chemicals, and even ozone, to form a wide variety of toxic products: nitroarenes<http://en.wikipedia.org/w/index.php?title=Nitroarenes&action=edit&redlink=1> , nitrosamines <http://en.wikipedia.org/wiki/Nitrosamines> and also the nitrate radical<http://en.wikipedia.org/w/index.php?title=Nitrate_radical&action=edit&redlink=1> some of which may cause biologicalmutations<http://en.wikipedia.org/wiki/Mutations>. Recently another pathway, via NOx, to ozone has been found that predominantly occurs in coastal areas via formation of nitryl chloride when NOx comes into contact with salt mist." [1]<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2453175/> http://en.wikipedia.org/wiki/NOx Production of NOx does require high temperatures or strong UV exposure. Open air release of LN2 would not entail heat, but, the Arctic Ozone Hole does migrate over the ESAS and thus, the volume of released LN2 would potentially be exposed to a strong enough UV energy to produce significant amounts of NOx. I could be wrong on this. Finding a way to use NOx to neutralize GHGs without open air release would seem optimal. Efficient high volume air movement through the system would be a key factor (as it is in all air capture concepts). High volume air contact systems stationed in remote areas is even more challenging. I have a few thoughts on how to approach the technical side of the issue which are not far removed from what I have already brought to this forum in past posts. A much larger version of this tethered system could provide a base structure for a GHG "Scrubber". http://www.flickr.com/photos/14529376@N00/2730542642/ A Salter Tether Ship wold be a good base for this approach. Hearing concepts on remote area high volume air contact means/methods from others would be helpful. Albert, I found this article on N2O which was a real eye opener for me. http://www.noaanews.noaa.gov/stories2009/20090827_ozone.html Using liquid air to seal methane vents may well work. Using it for general cooling of the sea or land surface will not. Oxides of nitrogen are critical in the formation of hydroxyl radicals. They therefore play a key role in the breakdown of methane. Although greenhouse gases in their own right, it's vital to accurately judge the effect of manipulations. An increase may paradoxically treat warming very effectively. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@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.
