Poisonous hydrogen Sulfide Gas!!!

[Attchoum]

I was about to ask how to get to that cenote X'kolak so I can go film some nice red H2S. But then I read Andy comment and I'm not sure anymore if I want to go put my rebreather and camera in that stuff...

still out of curiosity, where is that cenote???

[Jim Coke]

Andrew,

From memory, we were at X'kolak in 2001 during our transect. Our sonde had a 300ft cable, and we never touched bottom in this cenote. Our deepest water sample was collected at 250ft (maybe 300?). In any case the H2S concentration was just as potent at the greatest collection depth. This was a real witch's brew; you were fortunate if you were not wearing eye contacts at the time. Contacts in that situation could make for a very sad day.

All the classic sink collection sites over the scope of our transect had an H2S component to the FW/SW interface, so it's apparently universal to those types of cenotes in the northern half of the peninsula. I would offer that the variability in H2S concentration is just as universal over the northern half of the peninsula. We collected and sonded twice at Sabak Ha in different times of the year. H2S was present in notable concentrations one time, a weaker concentration existed during another sampling session. We have very spotty records for cenotes in the southern half of the peninsula, although the H2S component seems to exist in those classic sink cenote environments with a FW/SW interface.

Etienne - most all the "popular" cenotes in Yucatan state are on private property. Landowner relations and logistics are much different though than what you are used to in Quintana Roo. Google is universal. If you'd like to discuss it, I would prefer to do this off-forum. E-mail me at the QRSS web site.

[apitkin]

I just checked my logbook. I dived X'kolak on 11/17/1999. The H2S was detectable at 160 feet and got very strong at 200 feet. It just got worse as we got deeper. Our max depth was 396 feet. There was never any clear water - even shallow the visibility was only 30 feet. The guy from the local fire department who came along with us told us that there was a Coca-cola truck, as well as at least one corpse, in there. Sheck dived it in the 80s apparently. I always wondered what it was like then.

In Sabak-Ha the H2S layer was from 270-300 feet. Crystal clear below that. That was around the same time.

Andy

[diveongas]

I know of one case where a diver in one of the Mexican caves became ill with nausea and vomiting, following passing through a significant area of H2S. It was thought the chemical might have played a role in her illness. She had to be towed out from about 3000 feet in.

H2S can slowly pass through the skin to the circulatory system, but effect is generally not immediate. However, swallowing H2S rich water is extremely dangerous. The underlying mechanism is that the water will liberate H2S gas in the stomach. It then rises up through the esophagus (burp) to be inspired into the lungs. Any thing above 400ppm and it's lights out. Such a concentration is easily achieved. People often swallow water in fresh water springs, often not thinking about it to combat dryness. Hence the danger.

This is supposed to be covered in any decent Full Cave course, or at least it was with me, 12 years ago.

[GLM]

Just curious about the H2S layer in Hospital Hole... is it really intense like I need to worry about it messing up my regs etc.? Also (pardon the momentary hijack), does it have physical overhead sections or is it essentially a deep hole in the river? I've been wanting to do it for a while just to check it out.

[FW]

Hospital Hole is nothing like those in Mexico, but it will discolor some reg parts, and brass boltsnaps.

[TJDiver]

We encounter layers of hydrogen sulfide in a local quarry at the end of season, after the algae has died off. The pic below is me passing just over...and a little bit "in"...just such a layer. The layer was milky white until the strobe hit it.

[Gibby]

http://www.loltimeout.com/funny-pictures/underwater-river-what/

[divindoc]

Just curious about the H2S layer in Hospital Hole... is it really intense like I need to worry about it messing up my regs etc.? Also (pardon the momentary hijack), does it have physical overhead sections or is it essentially a deep hole in the river? I've been wanting to do it for a while just to check it out.

No idea what the H2S layer is like in Hospital Hole these days(and that's fine with me!).

I dove it in 1972, a bounce dive to 110' (yeah, stupid I know but when you're 18 you don't know what you don't know). All the metal parts of my gear were instantly tarnished, with the exception of my Mark V reg, which held up well. I can still see the scale on my Jetfins left by that misadventure - almost 40 years later!

[prov3125]

Just dove Hospital Hole on Saturday and there is definitely a whitish, wispy-looking H2S layer around 80'.