A study going on in an Ozark cave on CO2

[Ernie Coffman]

A nice article going on with several groups involved, on CO2 in caves and other scientific info that they're finding.
http://www.sciencedaily.com/releases/20 ... 210846.htm

My question, though, comes from an area in CA, where some of the months of the year, there are high concentrations of CO2 and why not at all times. The MLG folks had a major study there about fifteen years ago and don't believe they came up with any conclusive evidence, except that the foilage on the surface leeches into the ground and causes some changes in the atmosphere. If this is the case,then why isn't there more CO2 in all of the caves? These particular cases that they studied are really full of CO2--big time, where it almost killed a caver --during certain periods of the year.

I wonder if these research folks that are doing this study, have read the NSS findings that was presented at one of the conventions many moons ago by Jim Hildebrand and Dave Cowan, I believe it was?

[Phil Winkler]

Ernie, I can recall someone reporting on this effect some years ago. He stated that air flow within caves varies dramatically depending on weather conditions, barometric pressure, etc. Further, some caves get more organic material in them during the fall then in the spring. Rotting vegetation releases lots of CO2. So, the concentration can easily vary throughout the year. And, some caves get very little organic material washed into them.

Finally, I've noticed that bad air in caves varies greatly with whom I'm caving.

[Ernie Coffman]

Oh, you joker, Phil. Do you take your face mask off to prove that point.

If you heard that info at one of the conventions, then you probably heard the study done by MLGrotto, although there have been other presentations done...over the years. What really made MLG's presentation was the sale of their t-shirts to raise funds for their instruments and such. If you recall, it was the F.A.R.T shirt that really went well in the consignment room that year.

[fuzzy-hair-man]

Hey Ernie

Here's a good link I found about CO2 in caves, what causes high CO2 and what gets rid of it how to determine high CO2 and the physical effects on humans:

http://wasg.iinet.net.au/CO2ASFpaper.html

For my part AFAIK Phil is correct, vegetation, also bats respiration, and water off gassing (or something like that) cause high CO2, funnily enough they report that contrary to the popular belief CO2 doesn't neccisarily settle there is a tendency to settle but it can be defeated by opposing trends to mix and so high CO2 might be found at higher levels in the cave closer to the original source of the CO2. I can't say I usually experience this but then I usually stop the first time I hit CO2, so I wouldn't find out if it clears lower down. We do have a passage which is in the roof which routinely has high CO2 but only after the passage goes low enough that it wouldn't 'spill' back to the main passage, the end has a fair bit of built up organic matter which is probably what's producing the CO2.

We generally accept that changing air pressure causes the caves to breath and gets rid of the CO2 but some caves don't seem to have the internal volume to breath all that much and seem to be consistently full of CO2 others we see not 50m away won't have any CO2 at all and will remain clear. Some caves are seasonal bat roosts so will also tend to get high CO2 for that reason, it will clear a bit after the bats have left.

Another small cave and we were barely 3 metres inside the entrance and we had hit high CO2 it was really ridiculous and amazing!!

BTW Bungonia (mentioned in the link) is home ground at the current rate it shouldn't be too long before I start photosynthisizing

[Ernie Coffman]

G'day Fuzzy-Hair-Man! This was quite a surprise to hear from you, way downunder, as most of the mail has been on our bat problem in the northeast of late. Anyway about it, I was agreeing with Phil--and you, now--also, but was making a funny on Phil's last comment. You've got to go back and read that one liner of his.

This was quite a research project, which some of our guys did a number of years ago, also! And, the figures really jive right in there. As an example, one of the former members of the MLGrotto in California, went down into an area of "Dragon's Breath Cave" and almost didn't survive, as he was down in an area that hardly anyone could get to, since he was so much smaller than the others on the trip. The CO2 concentration was rated at 8 or 9 percent if I recall correctly.

In another area, not too far from the above event, there are a number of caves that have this problem, during certain times of the year. In the past, we never even thought of CO2, for we must have been caving during the "off season" but once we found out that it was there, we took precautions and carry a lighter with us to check on the concentration. One of the cave trips, we had several guys using carbide lamps and they went down into the pit part and started having flame problems. Thus, they came up into the larger room to work on the lamp, which was AOK, and then proceeded downward, again. Poof! Out went the lamp, again, so...we noticed as they were descending with a good solid flame, it started getting smaller and smaller, but after we asked them to slowly back up to the main room, the flame came out good and strong, again, so...indicated that there was the problem--a layer of CO2 as they went deeper into the cave.

Finally, it was funny on another trip, where we were digging near the bottom of this commercial cave, trying to find out if there was another room that was written up about in their historical novels. The guide was telling the tourists about the researchers down below, who were digging to get into another room, and a comment came from one of the tourists about "bad air" being down there. And, like all good guides and cavers, back then, he said something like "Oh! There's nothing more pure than cave air." And, just after that, one of our cavers had just come up from down below, saying that we had trouble down there with bad air and they needed to turn on the fire hose, to get the water gushing down into the troubled area. And, with that, I'll bid you a g'day!

[gulley.jason]

I've been working on a study in Florida caves on CO2 (for reasons other than exploration hazards) and here (which may not be transferable to your particular cave geology) we get high CO2 when its warm and wet (July, for instance). The reason for this (here) is because the CO2 is infiltrating down from the soil zone and the wee beasties that live in the soil respire more CO2 when its hot and wet.

[fuzzy-hair-man]

You've got to go back and read that one liner of his.

Got it, I find the chances of encountering that kind of bad air also increase when in tight crawlways

The CO2 concentration was rated at 8 or 9 percent if I recall correctly.

Been in similar concentrations I count myself fortunate to get out frankly CO2 is funny it does matter how fit, good, efficient you are it WILL get you!! there's no playing with it...

In another area, not too far from the above event, there are a number of caves that have this problem, during certain times of the year. In the past, we never even thought of CO2, for we must have been caving during the "off season" but once we found out that it was there, we took precautions and carry a lighter with us to check on the concentration. One of the cave trips, we had several guys using carbide lamps and they went down into the pit part and started having flame problems. Thus, they came up into the larger room to work on the lamp, which was AOK, and then proceeded downward, again. Poof! Out went the lamp, again, so...we noticed as they were descending with a good solid flame, it started getting smaller and smaller, but after we asked them to slowly back up to the main room, the flame came out good and strong, again, so...indicated that there was the problem--a layer of CO2 as they went deeper into the cave.

Have you done the trick where you get the lighter, light it above the CO2 layer and slowly lower the lighter down into the CO2, if the layer is distinct enough the flame will move up and away from the head of the light as you move the lighter down, it's a really cool trick we've had the flame hover some 3"- 4" from the top of the lighter you have to find somewhere where the CO2 layer is reasonably distinct.

It's a really good trick for when you have beginners with you and they are experiencing their first taste of CO2, I also get them to concentrate on how much effort (breathing) it takes to do stuff so they notice when their breathing rises abnormally often this is the first sign I get when heading into CO2 (sometimes the air changes, sort of feels musty and warm like, it's hard to explain) I will often confirm and also do regular checks with a lighter of course. Matches are also very useful (although less convenient than lighters) because they give you a grading, if the head burns but not the wood the air is getting pretty bad if the wood burns then you're OK, if the match head doesn't burn get out of there!

[Ernie Coffman]

Hey there fuzzy-hair-man, you wrote it all correctly! The trick using your lighter is, basically, the same thing that we did with the carbide lamp when we figured out what was happening.

Another great time of remembrance is when we had rapped down 120 feet (a hair over 36 meters) and several of us were in a small alcove off of the main room, wondering why we were breathing a little heavy and starting to sweat. It finally dawned on us that we were experiencing some problems and should get out of there. If I recall that was our first major experience with CO2, but probably had some smaller experiences before in the same general area. Anyway, one of our guys went to put on his ascending gear and...it wasn't in his pack. Thus, I loaned him mine and said to lower the gear back down, as soon as possible. So...there he started up and made the comment about half way up, that it felt a lot less of a problem as he proceeded up the slot. Well, yeah! It all went well, but it was a little scary for sure, while waiting down at the bottom. On top of that, we used to always say that "There's nothing fresher than a cave; and, the only bad air cave that we had ever heard of was in Texas.

[SpeleoRover]

I took Erik and Katherine in a few local Ozark caves when they were looking for suitable study sites. Great people.

My understanding of their work was that they were looking partially at the effects of water level fluctuation alongside CO2 - or something like that.

[Ernie Coffman]

Jason, as far as I know the CO2 studies have linked the soil and the flora of the area to the problem, but maybe your two scientists will come up with something new. Considering how far back the articles on the Texas cave was, I'm surprised, now that I think of it, as to any flora being in Texas. I know "hill country" there, is great for it, but not certain where this cave was down there. Anyway about it, have fun on the study of CO2, for it can put you away...forever! So be careful with it and research the studies that our guys came up with in the Mother Lode area of California.

[SpeleoRover]

For clarification - I'm not involved in the study at all. I happen to work for a nonprofit environmental education center that is known for our cave ecology programs and our proximity to caves. The Univ. of AR folks called out here to pick my brain about some easily accessed caves with some water fluctuation and I had some caving trips already planned and invited them along to check out a few holes.

I don't think they're really investigating high levels of CO2, which doesn't happen much in AR. I think they're focused on links in the hydrological and air fluxes and the interaction between the two. I really don't know much about the project other than that.

[gillip]

Fairly sure that they are looking more at C and O from the speleothems than CO2. C and O isotopes are useful paleoclimate reconstruction. Here is a basic explanation of how from a project proposal I did recently:
Changes in δ13C values will show changes in local vegetation, in this case from forest to fields. The δ13C are indicative of the vegetation present at the time of formation because plants utilizing the C4 photosynthetic pathway, which commonly occur in warm and arid climates, respire and decompose into carbon dioxide with higher δ13C values than C3 plants (Dorale et al., 1992).
Changes in δ18O may be used to indicate temporal changes. The oxygen contained in speleothems is derived mainly from infiltrating meteoric water. The δ18O may be enriched by evaporation, but in humid caves evaporation is not a problem. Evaporation prior to infiltration into the cave can also increase the δ18O, but in a shallow mantled karst setting, minimal δ18O enrichment by evaporation can be assumed. Higher δ18O values occur at higher temperatures, so the oxygen isotopic composition of the precipitation represented by the speleothem preserves the relative mean annual temperature (Hendy and Wilson, 1968).
Therefore, a shift from a cool/wet climate to a warm/arid climate may be recorded by increases in δ13C and δ18O in speleothem calcite (Denniston et al., 1999).

The sources, if anyone cares:
Denniston, R.F., Gonzalez, L.A., Asmerom, Y., Baker, R.G., Reagan, M.K., and Bettis,
E.S. III 1999: Evidence for increased cool season moisture during the Holocene.
Geology 27, 815-818.

Dorale, J.A., Gonzalez, L.A., Reagan, M.K., Pickett, D.A., Murrell, M.T., and Baker,
R.G. 1992: A high-resolution record of the Holocene climate change in
speleothem calcite from Cold Water Cave, northeast Iowa. Science 258, 1626-30.

Hendy, C.H. and Wilson, A.T. 1968: Paleoclimatic data from speleothems. Nature 216,
48-51.

[Spike]

Changes in δ13C values will show changes in local vegetation, in this case from forest to fields. The δ13C are indicative of the vegetation present at the time of formation because plants utilizing the C4 photosynthetic pathway, which commonly occur in warm and arid climates, respire and decompose into carbon dioxide with higher δ13C values than C3 plants (Dorale et al., 1992).

I personally find this bit pretty hard to believe, at least with a model this simple. Between 3 caves and 7 sample sites of cave waters I saw no less that 2 0/00 swings in δ13C at any sample site over a 12 month period. One site cycled from -15 0/00 to -3 0/00. The idea of having cave environments approach a closed system for soil C02 from C3 and C4 plants to dominate is a bit too far. Personally I think that seasonal and even long term changes in δ13C stem from the ability of the cave to breath due to temp gradiants and to a lesser extent, barametric changes. Also rain events influenced values as cave streams tried reached equilibrium with cave atmospheres that were exchanging carbon with drip pools that would swing between saturated and unsaturated. Way more complicated stuff than leaves rotting in a sinkhole changing the signature of a speleothem while the rest of the caves carbon cycles sit by and watch. Complicated enough I never really got enough a grasp on why my data changed the way it did until after my advisor split town. :) Sit down sometime and just list all the carbon sources, sinks, and pathways. Sorry for the soap box.

[John Lovaas]

Ditto to what Spike said.

I have been told by a chemistry professor that one of the "assumptions" in the process of obtaining dates from speleothems with the C & O isotope ratios is that the cave air environment is stable, and that atmospheric CO2 does not change- in the equation.

That isn't always the case; and in the case of Coldwater, it REALLY isn't always the case- and I'm speaking from bitter personal experience! ;-)

I've been curious what would happen to the data if the cave atmosphere CO2 was a variable in the equation- would it result in questionable or vague results?