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)
