Greg and list: Being one of your more active " biochar-in-the-soil friends " on this list, who is very weak in any " biogeochem perspective ", I had hoped someone else would jump in re your last sentence below. I have been a little active in combining Biochar and rock dust - but the (so far, minimal) emphasis of that combination has only been on the provision of growth-enhancing micronutrients.
Your concerns on the safety aspects of working with CaCO3 and nitric acid don't leave me with much hope, but possibly it is worth noting that there are a few Biochar researchers working with char intentionally produced with pH levels from 4 to 12 (for soils needing to get closer to neutrality). Through this response, I will relay the question to some Biochar researcher friends who might admit to being biogeochemists. Most Biochar researchers are soil scientists; I doubt this question has come up much for that discipline. Their involvement is only rarely on the sequestration side, either - the subject of this list. But I think I can speak for most Biochar researchers that they do want to support the development and use of NETs/CDRs that do not start with biomass - which will unlikely to ever be in over-supply. And a combination in soil could hopefully be the best of all worlds. Ron ----- Original Message ----- From: "Greg Rau" <r...@llnl.gov> To: "shaojun zhong" <shaojun.zh...@gmail.com>, "geoengineering" <geoengineering@googlegroups.com> Sent: Saturday, October 1, 2011 10:47:37 PM Subject: RE: [geo] Re: Monbiot Claims SAI "already tested ... with catastrophic results" I'd be very careful about adding CaCO3 to 0.1M nitric acid, the reaction is strongly exothermic. I'd cut the concentration and volume by 10 - 100x for starters, wear safety glasses and conduct in a safe place like a chem hood with access to sink. Better, do at soil acid molarity. Perhaps our biochar-in-the-soil friends could offer some biogeochem perspective. Good luck. -G ________________________________________ From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] On Behalf Of David Zhong [shaojun.zh...@gmail.com] Sent: Saturday, October 01, 2011 5:28 PM To: geoengineering Subject: [geo] Re: Monbiot Claims SAI "already tested ... with catastrophic results" Greg, Thanks for the West & McBride paper. In fact, a simple high-school chemistry experiment (or my “backyard” experiment) might provide an answer to your question of how to convert the aglime practise from a CO2 source into a CO2 sink. Let’s take five 500 ml beakers, to each we add 100 ml of 0.1 M HNO3 solution (i.e., a total of 0.01 mole of HNO3 in each beaker). Then we add 0.5 g, 0.75 g, 1.0 g, 2.0 g, and 5.0 g of CaCO3 to the five beakers, respectively (or 0.005, 0.0075, 0.01, 0.02, and 0.05 mole of CaCO3, respectively). Let’s disregard reaction kinetics here and assume that all the added CaCO3 will dissolve eventually. In the first beaker, 0.005 CaCO3 + 0.01 HNO3 -> 0.005 Ca2+ + 0.01 NO3- + 0.005 CO2 + 0.005 H2O CO2 emission: 0.005 mole, or 100% of the carbon from the added CaCO3 is emitted to the atmosphere. In the second: 0.0075CaCO3 + 0.01 HNO3 -> 0.0075 Ca2+ + 0.01 NO3- + 0.0025 CO2 + 0.0025 H2O + 0.005 HCO3- CO2 emission: 0.0025 mole, or 33% of the carbon from the added CaCO3 may be emitted to the atmosphere. In the third: 0.01 CaCO3 + 0.01 HNO3 -> 0.01 Ca2+ + 0.01 NO3- + 0.01 HCO3- CO2 emission: 0 mole, or 0% of the carbon from the added CaCO3 is emitted to the atmosphere. In the fourth: 0.02 CaCO3 + 0.01 HNO3 + 0.01 CO2 + 0.01 H2O -> 0.02 Ca2+ + 0.01 NO3- + 0.03 HCO3- CO2 capture: 0.01 mole, or 50% of the added CaCO3 served to capture CO2 from atmosphere. In the fifth: 0.05 CaCO3 + 0.01 HNO3 + 0.04 CO2 + 0.04 H2O -> 0.05 Ca2+ +0.01 NO3- + 0.09 HCO3- CO2 capture: 0.04 mole, or 80% of the added CaCO3 served to capture atmospheric CO2. It seems that whether the aglime practice is a source or a sink of atmospheric CO2 depends on the relative quantity of CaCO3 added to the soil to the quantity of strong acids present in (and/or added to) the soil system. I have very limited knowledge on soil acidity. My understanding is that there are three main sources of strong acids in the soil: acid rain (and/or acid pollution), nitrogen fertilizer nitrification in soil, and weathering (or oxidation) of sulfide minerals in soil and the quantity of strong acid in the soil system is generally limited (I could be wrong). Unless the addition of limestone to the soil enhances the production of strong acids in soil (e.g., enhance nitrification) and/or inhibits the acid neutralization reactions by other components in the soil system (e.g., silicate minerals), the portion of CaCO3 that is used to neutralize the strong acids in the soil system also helps to reduce CO2 emission to the atmosphere, as most of these strong acids, if not neutralized in the soil system, will eventually add to the acidity of surface and/or subsurface water and convert an equivalent quantity of dissolved bicarbonate ions to carbonic acid and therefore cause CO2 emission to the atmosphere. It is true that a certain portion of the dissolved CaCO3 may reprecipitate “down the line” and give an equivalent portion of the “captured” CO2 back to the atmosphere. Nevertheless, unless 100% of the dissolved CaCO3 is reprecipitated later, the net effect would still be CO2 emission reduction. Therefore, by increase the quantity of agliming to above the quantity of strong acids in soil, it is possible to reduce soil CO2 emissions to the atmosphere. The net CO2 emission reduction might be quantified as: Quantity of CaCO3 dissolved in soil - quantity of CaCO3 used to neutralize strong acids – quantity of CaCO3 reprecipitated afterwards. David. On Sep 30, 9:56 am, "Rau, Greg" <r...@llnl.gov> wrote: > Agree that if your only acid is carbonic then CO2 will be consumed, assuming > CaCO3 doesn't reprecipitate. If the soil acidity is caused by other acids > then you lose CO2 e.g.: H2SO4 + CaCO3 ---> CaSO4 + H2O + CO2. All farmers > care about is losing acidity when they limestone. In our current state of > "enlightenment" one would hope that by now some Ph.D. ag student has measured > the CO2 consequences as well as water hardness issues of crop limestoning, > but I'm not holding my breath.* > -Greg > > *but look what I found in a brief google > search:http://www.ornl.gov/info/ornlreview/v40_3_07/documents/article17web_W... > > > "Based on our best estimate, the application of 20–30 Tg of aglime in the > U.S., consisting of 80% limestone and 20% dolomite, would have resulted in a > net 4.4–6.6 Tg CO2 emissions in 2001." > > Guess we need more work to figure out how to convert this into a net CO2 > sink. Keep me posted. Meantime, back to the ocean? - G > > ________________________________________ > From: geoengineering@googlegroups.com [geoengineering@googlegroups.com] On > Behalf Of Tom Wigley [wig...@ucar.edu] > Sent: Friday, September 30, 2011 1:06 AM > To: geoengineering@googlegroups.com > Subject: Re: [geo] Re: Monbiot Claims SAI "already tested ... with > catastrophic results" > > It's a long time since I did anything in this field, so this is some ad > hoc thinking. > > Soil PCO2 is much higher than in the atmosphere. An old paper on this is ... > > Drake, J.J. and Wigley, T.M.L., 1975: The effect of climate on the > > chemistry of carbonate groundwater. Water Resources Research 11, 958–962. > > Adding CaCO3 will add Ca++ and HCO3- to the soil/groundwater. The > dissolution will reduce soil PCO2. So the flux of CO2 from soil to > atmosphere will decrease. But won't the bugs just work harder to keep > the soil PCO2 about the same? The climate/soilPCO2 relationship in the > above paper suggests that this is what will happen. > > So the net effect is probably small. > > Tom. > > +++++++++++++++++++++ > > On 9/29/2011 5:14 PM, Rau, Greg wrote: > > > > > > > > > There's a large literature on and practice of crop soil limestoning. In the > > context of CO2, my concerns would be added CO2 release from reaction of > > limestone with soil or precipt strong acids, and added downstream and > > groundwater hardness via dissolved Ca(HCO3)2 addition. The latter can be a > > big deal for communities that have to use the water, the potential for > > CaCO3 > > reprecipitation and scaling will go up, above that naturally present in the > > water, esp in limestone regions. For this reason it would be important to > > somehow keep the water below CaCO3 saturation. This goes away with disposal > > in seawater, which is why doing this close to a river mouth might be the > > best thing. Anyway, we eagerly await the results of your (backyard?) > > experiments. > > G > > > On 9/29/11 3:29 PM, "David Zhong"<shaojun.zh...@gmail.com> wrote: > > >> Greg, > > >> This might not be a bad idea. > > >> CO2 emission to the atmosphere through soil respiration is estimated > >> at about 60 GtC/a. Cutting down 10% of this natural emission will give > >> us about 6 GtC/a. For comparison, current anthropogenic carbon > >> emission to the atmosphere is about 8 GtC/a. > > >> To capture 6 GtC/a of carbon emission from soil respiration requires > >> mining and grinding a minimum of 50 Gt of CaCO3 per year (i.e., > >> 6/12X100). For comparison, current coal mining is estimated at about > >> 25 Gt/a. Limestone is certainly more abundant and wide spread than > >> coal. Using your estimate of limestone mining and grinding and > >> transportation cost of about $5/ton, the annual total cost would be > >> about $250 billion. > > >> Spreading 50 Gt of limestone to 10% to 20% of the land (or about 15-30 > >> million km2, about 0.3 to 0.15 kg CaCO3 per m2 per year) where soil > >> respiration is most intensive would probably be sufficient to > >> “capture” 6 GtC/a. > > >> Compared to “limestoning the ocean” scheme, this “limestoning the > >> soil" scheme would cut CO2 emission to the atmosphere immediate, > >> instead of waiting for years or tens or hundreds of years. > > >> As for your two concerns, I am sure that if the soil system is > >> overloaded with limestone, the end product of limestone dissolution > >> would be dissolved bicarbonate ions instead of carbon dioxide. > >> Limestone landscapes are found all over the continents and people have > >> been living happily in limestone regions for generations. I doubt that > >> the hardness of the resulting runoff of a “limestoning the soil" > >> scheme will be any worse than that of the watershed of a limestone > >> region. > > >> I am sure that there will be some other environmental and/or > >> ecological “side effects” or risks. But I am also sure that any or > >> every “solution” to such a planetary scale problem will carry risks. > >> The question is, are these risks manageable? > > >> What do you think? > > >> David > > >> On Sep 29, 11:14 am, "Rau, Greg"<r...@llnl.gov> wrote: > >>> That would work for me a la crop liming IF: 1) soil acids other than > >>> carbonic acid are such that CO2 is not emitted to the air from the acid > >>> limestone reaction, and 2) the hardness of the resulting runoff is within > >>> environmental standards. How about limestoning the mouths of rivers to > >>> mop > >>> up excess dissolved CO2 - there are no hardness standards for discharge > >>> to > >>> the ocean. Then again, by the time rivers discharge to the ocean they've > >>> probably pretty much degassed and equilibrated with air pCO2. > >>> -Greg > > >>> On 9/29/11 10:35 AM, "David Zhong"<shaojun.zh...@gmail.com> wrote: > > >>>> Would it be more effective (and perhaps simpler) if the limestone is > >>>> distributed to a large area of land (ideally in regions with heavy wet > >>>> precipitation and with organic matter rich soil) instead of the > >>>> upwelling > >>>> regions of the ocean? > > >>>> After all, limestone dissolution in normal rainwater (pH< 5.6, ionic > >>>> strength ~ 0) is much faster than in seawater (pH> 7.6, ionic > >>>> strength ~ 0.7) and natural CO2 exchange (or flux) between soil > >>>> and atmosphere is on the same order as that between ocean and > >>>> atmosphere? > > >>>> Just a thought. > > >>>> David. > > >>>> On Sep 29, 9:12 am, "Rau, Greg"<r...@llnl.gov> wrote: > >>>>> Thanks, Tom. I think we all can agree that the volume of CaCO3 > >>>>> undersaturation in the subsurface ocean is vast, it is a very effective > >>>>> consumer (60-80%) of natural carbonate rain, and hence is a massive > >>>>> (re)generator of carbonate alkalinity that can in turn consume ocean > >>>>> and > >>>>> atmospheric CO2. It follows that adding additional CaCO3 to the > >>>>> undersaturated regions of the ocean, especially particles of high > >>>>> surface > >>>>> area/volume, will generate additional (new) alkalinity and CO2 > >>>>> consuming > >>>>> potential. The only question then is can this occur in shallow enough > >>>>> water > >>>>> (e.g., upwelling areas) such that its communication with and effect on > >>>>> the > >>>>> atmosphere occurs on a time scale shorter than the usual 1kyr involved > >>>>> in > >>>>> thermohaline ventilation of deep water. In this regard the subsurface N > >>>>> Pacific Ocean, being first up for such ventilation, would seem to hold > >>>>> the > >>>>> most promise. Then there is the CaCO3-challenged Southern Ocean. > >>>>> Or am I off base? > >>>>> Anyway, if you don't like the rates afforded by natural seawater > >>>>> carbonate > >>>>> undersaturation, there is a relatively straightforward way to change > >>>>> this:http://pubs.acs.org/doi/abs/10.1021/es102671x > >>>>> Regards, > >>>>> Greg > > >>>>> On 9/28/11 6:18 PM, "wig...@ucar.edu"<wig...@ucar.edu> wrote: > > >>>>>> Regardless of possible inhibiters, I think that kinetic limitations > >>>>>> make > >>>>>> this an unlikely possibility. > > >>>>>> See ... > > >>>>>> Plummer, L.N. and Wigley, T.M.L., 1976: The dissolution of calcite in > >>>>>> CO2-saturated solutions at 25°C and 1 atmosphere total pressure. > >>>>>> Geochimica et Cosmochimica Acta 40, 191202. > > >>>>>> Plummer, L.N., Wigley, T.M.L. and Parkhurst, D.L., 1978: The kinetics > >>>>>> of calcite dissolution in CO2-water systems at 560°C and 0.01.0 atm > >>>>>> CO2. American Journal of Science 278, 179216. > > >>>>>> Tom. > > >>>>>> ++++++++++++++++++++++++++++ > > >>>>>> On 9/28/2011 1:44 PM, Rau, Greg wrote: > >>>>>>> Thanks, David, for the info. Certainly agree that limestone > >>>>>>> dissolution > >>>>>>> only > >>>>>>> works in undersaturated, sub-surface waters, which Harvey goes to > >>>>>>> some > >>>>>>> lengths to locate and model for carbonate dissolution. As for P, I > >>>>>>> doubt > >>>>>>> carbonate rain would have much of a effect on surface ocean P since > >>>>>>> there > >>>>>>> is > >>>>>>> precious little there anyway. What happens at depth could be a > >>>>>>> different > >>>>>>> story. Easy enough to test: take some seawater with measurable P, mix > >>>>>>> in > >>>>>>> calcite powder, and see what happens to dissolved P. As for P > >>>>>>> inhibition > >>>>>>> of > >>>>>>> calcite dissolution, sample or make calcite undersaturated seawater, > >>>>>>> add > >>>>>>> or > >>>>>>> remove P, add calcite, measure differences in resulting alkalinity or > >>>>>>> DIC > >>>>>>> in > >>>>>>> the preceding treatments. Even better, let's just rain calcite powder > >>>>>>> into > >>>>>>> a > >>>>>>> likely spot in the ocean and measure vertical profiles of P, DIC, > >>>>>>> alkalinity, > >>>>>>> etc and compare to Berner et al models (and Harvey's!). > >>>>>>> A paleo example: following the PETM event carbonate rain rate went > >>>>>>> from > >>>>>>> zero > >>>>>>> to huge numbers while there was not much change in organic C > >>>>>>> accumulation, > >>>>>>> so > >>>>>>> something in surface waters was getting enough P to make the OC > >>>>>>> despite > >>>>>>> high > >>>>>>> carbonate rain, if that is your concern. > >>>>>>> Another idea: certainly inhibition of carbonate precipitation in the > >>>>>>> ocean > >>>>>>> is > >>>>>>> a major player in setting ocean water column and atmospheric C > >>>>>>> levels. To > >>>>>>> what extent have these inhibitors (P, Mg, organics, etc) varied in > >>>>>>> the > >>>>>>> past, > >>>>>>> (how) have they affected C levels, and might > > ... > > read more » -- 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. -- 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. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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