White Layer in Travis

[ianr33]

I was at Windy Point today and once again at around 100 feet there is a very dense,milky white layer that reduces visibility to a few inches. does anyone know for sure what this is? I'm thinking it is a calcium sulfide precipitate formed from the reaction of soluble calcium compounds (calcium hydrogencarbonate,maybe calcium sulfate) and H2S that is produced as the organic layer sitting on top of colder,denser water decomposes. Am I getting warm here?

Once through this nasty layer vis is pretty good. 20 feet??

 

[archman]

Perhaps you should visit the Water Chemistry Discussion Board. That's over the heads of 99.9% of divers, many limnologists, and me. That's not even in my texts... I looked.

 

[ianr33]

Over YOUR head !

I feel honoured Sir

 

[do it easy]

Where is this water chemistry board? I sometimes dive in stuff that is similar to that, but I'm not sure what it is or if I should be afraid.

How thick was the layer?

 

[jonnythan]

My chemie source thinks it may just be calcium carbonate which fits in with the lake's high pH.

Go diving, grab a sample, and add vinegar. See if it fizzes

 

[ianr33]

It was maybe 5 feet thick. Kinda spooky as the lake in that area has many trees of all sizes,getting tangled up in one in 2 inch vis would not be fun. Supposedly the layer has a taste of hydrogen sulfide but I have never noticed that. (Probably concentrating too hard!) Hydrogen sulfide is most definately poisonous but the concentration of it is probably pretty low as I am still here.

 

[archman]

Where is this water chemistry board? I sometimes dive in stuff that is similar to that, but I'm not sure what it is or if I should be afraid.

I made it up. Ha ha.

Ian's getting very technical, at the level used by chemical oceanographers and other water chemists. Most college limnology courses don't progress beyond what jonnyathon's talking about.

As for that milky layer, I see an identical thing following heavy rains adjacent to coral marl parking lots! I guess that's somethin' different.

H2S puts mice into deep hibernation, and there's some work underway to see if we can apply it with people going on intergalactic space journeys, or who wish to sleep through the next few versions of Microsoft Windows. Some diver should help explore the boundaries of science and take one for the team!

 

[do it easy]

I made it up. Ha ha.

H2S puts mice into deep hibernation, and there's some work underway to see if we can apply it with people going on intergalactic space journeys, or who wish to sleep through the next few versions of Microsoft Windows. Some diver should help explore the boundaries of science and take one for the team!

Ha ha ha. I did take one for the team a few dives ago. Local quarry dive. Really hazy silty vis from 50-60 feet, but under that layer, the water was not turbid, but still dark, and I could smell/taste a rotten egg. There was a fine black silt and it seemed like the water actually absorbed light. I could see my fins, but even with a 10W HID pointed at them, they weren't as bright as I expected. Afterwards, I realized that water must have been like tea or grape kool-aid(!). When I surfaces, I could still smell traces of rotten eggs. I'm not sure if the H2S was concentrated enough to kill me?

On another dive, there was a similiar white, silt layer, but it was more cohesive and if looked like clouds just about the dark stuff. I could swim at a constant depth and it felt like I was flying high on the clouds.

I think that I'll start measuring pH when I dive, just to see how the water chemistry changes through out the season. Let me know when you find the water chemistry discussion forum so that we can ask those chicken biters about this stuff or if there are more definative tests. Jonnythan has a good test, but how do we know that the sample just isn't bent?