Science Buddies: "Ask an Expert"

My daughter is thinking about doing a science fair project on storm water. She wants to collect the storm water from a nearby drainage area during the next rain and then run the water through natural barriers such as mulch, grass, sand etc. She would test the water first, for metals and then run the water through the natural barrier and test it again. I have looked for test strips that would test for metals but only find where you have to send it away to a lab. I found one company but the review for that test strip wasn't that good. I was wondering if you knew if it is possible to test for metals with a home kit before I waste money buying them? Thanks for any help!

Hey there zabanda!

Any particular metals you're going to be testing for? I've seen some that cover a variety of metals, and some that only test for single metals. Single tests are probably more accurate for any specific metal since they tend to rule out interference from other metals. Test strips are probably your only option for any at-home testing for something like this. But yes it's definitely doable. I'll post a few examples of what I can find. I can't personally vouch for their accuracy since I've never used them, just a quick google. I would appreciate input from any others who may be more knowledgable in this area than myself.

These may be the same ones you've looked at:
http://www.sensafe.com/product.php?recordID=480309

Here's one for manganese:
http://www.filterwater.com/pc-211-9-man ... 7aodmc0aww

Mercury:
http://www.filterwater.com/p-344-mercur ... boris.aspx

Thanks so much! I actually had thought of a multi test strip so we could test for several metals simply for the fact that once she collects the storm water, there would be a greater chance of finding some metal in the water. If she uses a single metal test strip I am afraid that metal won't be found in the storm water. I hope that makes sense. Unless, however, there is one particular type of metal that is almost certain to be found. This leads to another question. What if she can't find storm water that registers metal. Is there a way she can "pollute" the water herself (with a certain metal) and then test, I am not sure how to do that or if it is possible. Thanks for all the help!

Hi Zabanda,

In answer to your question about 'spiking' the storm water with a metal salt--yes, you certainly could and should do that as a positive control to make sure your test strips are working. Run-off water could potentially carry lots of different metal ions depending on where it came from. I would look for lead, definitely, since that is a common pollutant, but copper, zinc, manganese, iron, cadmium and mercury could also be tested for.

I clicked on one of the links suggested by cbrambley (http://www.sensafe.com/product.php?recordID=480309) and found the detection strips described, but it also said when more than one metal is present “the values are combined” which tells me that you can’t distinguish one metal from another. If that is something you wanted to do then you need to use the test strips that are specific for one type of metal ion.

Do you have access to a college chemistry lab? That would be very helpful if you want to choose a specific metal to test. Metal ions from metal salts--compounds such as copper sulfate or iron chloride--are water soluble and that is what you would be looking for I think in the storm water, right? Metal particles such as bits of rust, iron oxide, would probably not be detected by the test strips. You will have to do some searching on the web to find out what concentration of metal salt to use to ‘pollute’ the storm water.

As to the materials you plan to use to mitigate the pollution, I am not sure how effective they would be in removing dissolved metal ions from the water. Waste water treatment plants use bacteria to remove a lot of pollutants, but there are some materials such as certain types of clay that can absorb metals. Here’s an article I found on new methods for removing heavy metals from waste water: http://www.sciencedirect.com/science/ar ... 5210001334

I hope this helps. If you have more questions, please repost to this thread.

Best wishes,

Sybee