Dissolve Oxygen (DO) meter is frequently used in river study. Calibration in the laboratory is not a problem, but it is difficult to calibrate DO meter in the field, especially for streams with different temperatures.
The temperature is usually autocorrected with the meters both in field and in lab, some need you to input the local pressure prior to calibration.
I have found that adding a small amount of DI water to the resevoir container and loosely leaving the probe (as opposed to screwing on the reservoir) can help with calibration.
Hope that helps.
Maybe you want to check this RG discussion: https://www.researchgate.net/post/What_is_the_proper_way_to_perform_DO_probe_calibration
Yes, it was helpful to some extent.
Thank you Carlos Araújo Queiroz.
We only field calibrate when absolutely necessary - such as hard wired permanently deployed meters. It's easy to make up a 0% and 100% solution in the field (or 100% air of course). The main challenge in the field is stable temperature. Water calibrations are better temperature-buffered than air, so are better for field calibration. But the temperature still changes. Hence speed is important for the 100% solution. We use twenty tips from 1 bucket to another to saturate, then complete the calibration within 2 minutes. We stopped using a bubbler in the field to maintain saturation for longer because that caused a faster increase in temperature, and hence earlier departure from 100%. Another key point is having the probe temperature stabilised with the calibration water. For our deployed sensors, they have been in the water a long time, so are stabilized with river water temperature. Then making the 100% solution using stream water means the probe and solution temperatures will be very close. That's not the case for portable probes, hence you'd want to leave those in the river to stabilise before making up the solution. We stopped calibrating portable probes in the field especially now we are only using fluorescent sensors that hold calibration longer. Otherwise you're just mucking up a good lab calibration by trying to redo it in the field.
Great
Thank you Thomas Kennedy Wilding for Sharing such rich experience.
Well. Sir it also depend on the meter type. That either it is automatic or manual. Sir share your DO meter type and model.
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