diving in anoxic waters

[dd2kimo]

Hello folks, I am new to the life of scuba, but have set forth on a rather rigorous schedule of training and diving. Part of the diving will take me into anoxic water (<1 mg/L dissolved oxygen), where decomposition of lake bottom organic material results in the release of hydrogen sulfide bubbles. In some of the lakes, the water contains a rather strong sulphur smell at depths below 35 feet. I was wondering if any special precautions are required if one must venture into such areas?

 

[scuba-sass]

Okay, I want to know who's been sniffin' the water at 35 feet?

Understand that I know nothing about this, but common sense says - as long as it doesn't eat thru your skin or exposure suit, who cares what it smells like? You're not breathing the stuff down there...

Oh, alright - your non-diving friends and family members might be a little put off when you try to ride home with them.

Welcome to the wonderful world of scuba,
And Happy Diving,

Scuba-sass

 

[MikeFerrara]

I'm nor an expert on it but the reason you can smell/tast it under water is that it permeates through your skin (I've been told). I believe a large enough exposure can make you ill. I don't know if there is a chance of any kind of permenant damage.

 

[FredT]

Originally posted by MikeFerrara
I'm nor an expert on it but the reason you can smell/tast it under water is that it permeates through your skin (I've been told). I believe a large enough exposure can make you ill. I don't know if there is a chance of any kind of permenant damage.

The tiny droplets of water leaking past the diaphram seal in your reg's exhaust valve is atomized and inhaled at the next breath. This allows you to smell/taste it

This is the same way you can tell if you're getting close to the three day old corpse when body snatching in zero vis. The taste is distinctive. uke:

If diving polluted or known bio-hazard waters I'd suggest using a band mask and dry suit. Simple low O2 is not a serious issue by itself if you don't mind eating alone. It's amazing how well that sulfide stuff soaks into your hair!:whoa:

 

[dd2kimo]

Thanks folks, so far it appears the only potential detriment is to my social life. I'll make sure to take a few short excursion first to see how I stomach the experience.

 

[pipedope]

If there are real biohazards or chemical polutants then special equipment and procedures are called for.

Sorry Fred, the band mask doesn't cut it, you need at least a full helmet with dry suit and dry gloves, with double exhaust valves in the helmet. That is just for starters. Depending on the hazard it can get worse.

Divers working in the nuclear power plants wear special shell suits and nearly always the Desco air hat. The Desco gets the job because it is all metal so it doesn't trap any radioactive contaminates and it is a free flow hat so there is nearly zero chance of any water getting inside.

For chemical contaminates you have to make sure that your suit, suit seams, gloves, boots, helmet, neck dam, umbilical and anything else that will contact the water will withstand the chemical for the duration of the dive plus a safety factor.
In some cases the dry suits become a consumable item, being replaced after 45 minutes or so in the water. Can you say, "Expensive job?" I think you can.

For normal muck on a normal lake it is not so much a problem.

Watch out, some lakes have some nasty microscopic critters in them that will do bad things to you.
Getting into the muck at the bottom of Lake Appoka here in central Florida can get you some real nasties. ;-0
The worst lakes seem to be the ones that have been getting lots of fertalizer and pesticide runoff.