Science Buddies: "Ask an Expert"

Hello, my 5th grade son would like to test 4-5 different outdoor lakes, rivers and ponds in our town for fertilizers and the basic panel that can be purchased in kits: pH, Alkalinity, Water Hardness,
Total Dissolved Solids. I am a non-scientific mom who really wants him to do most of the project and conclusions himself, but realize I need to assist him. Where can we find information as to what the results actually indicate, particularly in their comparisons? If water is hard or has a lower/higher pH, for example, than a sample from another area, how do we determine what that actually means? We need guidance from the point that we get the test results in order to make conclusions, I guess.

Additionally, at the Science Fair information/mentoring session held last week, one judge advised us against testing for bacteria, stating they don't like non-microbiologists to risk getting sick from it or spreading it in their homes. Another judge later countered her to us, stating that we shouldn't be afraid of a little bacteria. My kids would love to test for it. What are your thoughts on it?

Thank you so much,
Nicole

Hi Nicole,

I've seen many science projects where kids test for bacteria. The key is, once you're growing the bacteria, don't touch them or play with them anymore. Science Buddies has some guidelines on microbiology:

https://www.sciencebuddies.org/science- ... tion.shtml
https://www.sciencebuddies.org/science- ... ates.shtml
and more under "microbiology" at https://www.sciencebuddies.org/science- ... l?From=Tab

Once you've put the bacteria in your plates ("innoculated"), wrap the edges of the plates with tape or Saran wrap or something similar. Don't open them again. The reason is that a single harmful bacteria in the pond water might not cause any danger, but once you've given them food and let them grow up into a colony, it could be infectious. As long as you follow that guideline, I think you're perfectly safe. (And of course, I'm sure you'll wash your hands after dealing with the icky water.) You can also get a special kind of agar plate--I think it's called "Coligel" that turns a certain color when E coli--fecal bacteria--grow it it, which would give you an idea of sewage contamination.

This guide to interpreting water quality results might help you: http://pubs.ext.vt.edu/356/356-489/356-489.html

--Amber

That's a HUGE help. Thank you!

Hi,

I completely agree with Amber; if your son is interested in growing bacteria, then this would be a good choice for a science fair project. Most bacteria are not pathogenic, and you would be culturing natural water sources and following the safety precautions that Amber has described, so you would be very unlikely to be exposed to pathogenic bacteria.

However, since you are still trying to pick a topic, here are a couple of water-related projects that your son might be interested in doing:

https://www.sciencebuddies.org/science- ... p011.shtml

https://www.sciencebuddies.org/science- ... p041.shtml

If you want to measure fertilizers, you will need to measure nitrogen and phosphorus. Here are websites with protocols for phosphate and nitrate analysis. I think these would be too complex to do for a 5th grader, unless you had a local chemist with a spectrophotometer to help you set up the assays.

http://science.csumb.edu/morocojo/chem_ ... eMeth.html

http://www.epa.gov/nerlcwww/m353_4.pdf

Good luck! Let us know if you need any more help.

Donna Hardy

This English major thanks you immensely!!

Hi,

You are welcome. If you are an English major, then you can help your son with one very important part of the project, which is communicating the results.

Donna Hardy