Dissolved Oxygen @ 500% above saturation?

BruceRat brucerat at aol.com
Tue Mar 12 11:02:53 EST 1996


I have been measuring dissolved oxygen (DO) in freshwater ponds for 3
years, and have recorded values as high as 500% above oxygen saturation
level (up to 40 mg/liter).  A freshwater ecologist friend with extensive
experience in the field, says that's crazy, or at least highly suspect.
He's never recorded values over 250% saturation.  Anyone out there got
readings in the 30-40 mg/liter range?    I've been using a YSI Model 57 DO
meter, that uses a membrane-shielded combination gold/silver electrode in
a probe.  I have not done Winkler tests on the water.  YSI tech support
indicates that bubbles of pure oxygen could be implicated, if they stick
to the membrane.  I'm in a quandry (as is my whole thesis.)  Any advice?
Bruce Ratcliffe, Fresno, CA   (BruceRat at AOL.COM)





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