If one is interested in silicate addition to the ocean (both for direct chemical and indirect bio effects on C), then I refer you to these links and refs therein: http://m.iopscience.iop.org/1748-9326/8/1/014009/pdf/1748-9326_8_1_014009.pdf http://www.earth-syst-dynam-discuss.net/2/551/2011/esdd-2-551-2011.pdf
Lots more silicate minerals around than just ash, and yes potential for positive (and negative) cation and anions effects on bio C, but lets find out. Greg From: Oliver Tickell <[email protected]<mailto:[email protected]>> Organization: Kyoto2 Reply-To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Date: Wednesday, August 21, 2013 7:59 AM To: geoengineering <[email protected]<mailto:[email protected]>> Subject: Re: [geo] New article on non-anthropogenic ocean fertilization in MEPS Thanks! My last sentence should have read "And of course the other question is re the chemical composition of the silicate in the ash and its particle size as this will determine its quality as a source of silicic acid." So you understood. the rate of weathering is proportionate to surface area so small particles are hugely more effective at releasing silicic acid than large ones. Olivine grain sizes of 0.1mm are proposed for terrestrial application and far smaller than this (~ micrometre scale) for marine use so that the particles can weather during their residence in the water column. The 'powdery' fraction of the ash will give the greatest silicic acid contribution. It's hard for me to comment further without seeing the paper but it's good to know that these questions have been considered, Oliver. On 21/08/2013 15:05, Chris Vivian wrote: Oliver, Bear in mind that the North East Pacific is a high-nutrient, low-chlorophyll (HNLC) area that is known to be limited by iron. The paper gives estimated sea water concentrations of silicate in the North East Pacific in the top 20 metre mixed layer in August 2008 when the volcanic eruption occurred of 5,000-15,000 nM (nana molar) compared to an estimated 6-20 nM supply from the ash fallout over the fertilized area in the Gulf of Alaska. Your second point was unclear but I assumed you were querying the release rate of the silicate from the ash. The ash used in the experiment was collected on a fishing boat during the eruption and stored dry in containers. The experiment only used the < 2 mm size fraction. The release rate of silicate in the experiments was 170 nmol silicate per gram of ash in the first hour and up to 585 nmol silicate per gram of ash after 20 hours. Chris. On Wednesday, August 21, 2013 10:12:19 AM UTC+1, Oliver Tickell wrote: IMHO the significance of the silicic acid would depend on the time of year. In the spring silicic acid is generally abundant so adding more of it would make little difference. One it has all been used up and diatoms are giving way to other phytoplankton a boost of silicic acid would give rise to a second diatom bloom - so it would be very significant. And of course the other question is how effectively the chemical composition of the silicate in the ash and its particle size as this will determine its quality as a source of silicic acid. Have the authors given any serious examination to such questions? Oliver. On 21/08/2013 09:55, Chris Vivian wrote: Oliver, ï¿1Ž2 I have seen the paper but cannot post a copy online. In the paper the authors did measure the release of nitrate, nitrite, ammonia, phosphate and silicate in leaching experiments and concluded that the impact of these macronutrients released from Kasatochi ash on primary productivity was probably minimal.ï¿1Ž2They also suggested that the release of trace metals other than iron could also have influenced phytoplankton growth. ï¿1Ž2 Chris. ï¿1Ž2 On Monday, August 19, 2013 4:23:59 PM UTC+1, Oliver Tickell wrote: I have not found an open source version of this paper yet, but here is a related one. http://www.biogeosciences.net/10/3715/2013/bg-10-3715-2013.pdf They do recognise that diatoms need silicic acid but do not seem to have thought of volcanic ash as a source of silicic acid, only of iron. Re olivine application, it is worth noting that olivine is a mixture of Mg silicate and Fe silicate. Some proportion, to be determined, of the iron in olivine will become bioavailable as weathering progresses. Oliver. =============== The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study A. Lindenthal1 , B. Langmann1 , J. Patsch ï¿1Ž2 2 , I. Lorkowski2 , and M. Hort1 1 Institute of Geophysics, KlimaCampus, University of Hamburg, Hamburg, Germany 2 Institute of Oceanography, KlimaCampus, University of Hamburg, Hamburg, Germany Correspondence to: B. Langmann ([email protected]) Received: 29 June 2012 ï¿1Ž2 Published in Biogeosciences Discuss.: 26 July 2012 Revised: 18 April 2013 ï¿1Ž2 Accepted: 8 May 2013 ï¿1Ž2 Published: 5 June 2013 On 19/08/2013 15:03, Oliver Tickell wrote: This is very odd. Based on the abstract only (article behind paywall) it appears that they attribute the diatom bloom to iron fertilisation. Oddly they have not considered the role of silicic acid from the dissolution of Mg silicate species in the finely powdered volcanic ash. Silicic acid is often the limiting nutrient for diatoms, as they use it to make their silica shells. There is ample geological evidence of diatom (specifically) blooms being associated with falls of volcanic ash. Is anyone able to post the actual article? Oliver. On 17/08/2013 17:13, Wil Burns wrote: FYI. wil MEPS - Vol. 488 - Table of contents<http://www.int-res.com/abstracts/meps/v488/> Mar Ecol Prog Ser (Print ISSN: 0171-8630; Online ISSN: 1616-1599) Copyright ï¿1Ž2 2013 Inter-Research. Published August 15 Olgun N, Duggen S, Langmann B, Hort M, Waythomas CF, Hoffmann L, Croot P Geochemical evidence of oceanic iron fertilization by the Kasatochi volcanic eruption in 2008 and the potential impacts on Pacific sockeye salmon MEPS 488:81-88<http://www.int-res.com/abstracts/meps/v488/p81-88/> | Full text in pdf format<http://www.int-res.com/articles/meps2013/488/m488p081.pdf> -- Dr. Wil Burns, Associate Director Master of Science - Energy Policy & Climate Program Johns Hopkins University 1717 Massachusetts Avenue, NW Room 104J Washington, DCï¿1Ž2 20036 202.663.5976 (Office phone) 650.281.9126 (Mobile) [email protected] http://advanced.jhu.edu/academic/environmental/master-of-science-in-energy-policy-and-climate/index.html SSRN site (selected publications): http://ssrn.com/author=240348 ï¿1Ž2 Skype ID: Wil.Burns Teaching Climate/Energy Law & Policy Blog: http://www.teachingclimatelaw.org -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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