Question: Dissolved Oxygen Testing and Citizen Science

My background is mostly industrial- specifically pharmaceutical. So much of the testing was guided by something like The USP. The instruments were usually moderately expensive ( ph meter about $2k usually using a ross electrode in the $500 range). Turbidity, conductivity, total organic carbon (toc), uv/vis, were routine tests. Other more expensive tests were done on extracts less often.

As for storm sewer testing, we pulled those with an isco sampler. P h was tested routinely, before preserving the sample and sending it to a certified lab. We would do some other tests , in house, since the the lab wasn't certified ( for info only). Some were wet chemical like oil and grease. Some were biological. Occasionally we would have a problem that would require extra testing with something like a gc/ms. Which was an instrument we were lucky enough to have, probably because of the pharmaceutical business we were in.

These answers came from Twitter user @Sulfur_Blue on a tweet I shared through the Public Lab Twitter account:

Consider overall costs / maintenance (membranes require electrolytes), calibration, logging compatibility / data transfer, portability, can the electrode be replaced or the entire unit, how often are parts discontinued, warranty, detecting limits.

For more general scientific information check out major supplier websites for more detailed specs, features, functionalities, data logging methods....then scale down knowing what features you need and which are optional.

Major vendors will often provide demos of the instrument for your samples. Contact the local sales rep. The sales rep is also helpful for product support such as method development, troubleshooting or other questions. Consider non-membrane electrodes https://www.vernier.com/products/sensors/dissolved-oxygen-probes/odo-bta/

Tweets here: https://twitter.com/Sulfur_Blue/status/1048297687760560128 https://twitter.com/Sulfur_Blue/status/1048298791567155200 https://twitter.com/Sulfur_Blue/status/1048298189512560640

• do not use DO sensor

On a monthly period, at a number of sampling locations in the watershed, air/water temperature are collected and:

• DO, Hardness, and Alkalinity are done manually using titration; e.g. DO is accomplished using the Winkler method.

• pH is accomplished using a digital meter (Hanna 9126 I think)

• samples are sent to state lab for metals analysis (using ICP). Every 5th sample is duplicated to assist state in evaluating our process and a blank sample is sent to the lab to evaluate the lab analysis.

We go through a yearly evaluation by the state, done in person, on an unknown sample provided by the state. A bit nerve wracking.

Our sampling and analysis effort is focused on a Level 5 EPA Superfund site (abandoned silver mines)

Hi @Belkinsa ! What are you hoping to use the data for? We recently worked with one of the LaMotte kits to talk about different water quality parameters with students. Not real precise, but a good teaching tool.

https://publiclab.org/notes/stevie/04-18-2018/lamotte-and-earth-force-low-cost-water-monitoring-kit

Sorry for the delay. I was thinking that the data could be used for monitoring rather than education because that data could be used as a red flag. But I think this would work better for rivers. I think I'm overthinking this.

@belkinsa I’d strongly suggest the Winkler test for monitoring DO. It’s easy, can be done reliably by 14+ yr old kids. Works on lakes, rivers, etc. Equipment needed is pretty cheap. Chemicals are readily available.

Thank you @MadTinker, I updated the page with that info, hopefully it's right.