Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Ask questions about projects relating to: biology, biochemistry, genomics, microbiology, molecular biology, pharmacology/toxicology, zoology, human behavior, archeology, anthropology, political science, sociology, geology, environmental science, oceanography, seismology, weather, or atmosphere.

Moderators: AmyCowen, kgudger, MadelineB, Moderators

67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hi,
My name is Sirenity and I am a student at Adlai E. Stevenson High School. My partner and I are doing a phytoremediation project, and we really need some help figuring out some details. We are testing the number of mustard plants vs the amount of lead concentration in water. Our independent variable is the number of mustard plants. The dependent variable is the amount of lead concentration in our water sample. Our idea is to see if the mustard plants will take up the lead. We want to have a lead concentration of around 25 ppb, but really our range is anywhere from 15 - 40 ppb, which we felt would reflect polluted water levels. Our dilemma is how to obtain lead and put it in the water samples, and how to measure the amount left in it at the end of our experiment. Any help on how to carry out our project would be greatly appreciated!
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

That's a great idea for an experiment, but it has some problems as you pointed out--where to get the lead and how to measure it. If you had access to a university chemistry lab there would be no problem, but I'm assuming you have only your high school lab to work in.

Lead metal, say from a fishing sinker, will dissolve somewhat in vinegar (distilled white) to give lead acetate and you can use this as your source of lead ions, Pb2+. You won't need much as you are working in the ppb range.

Now, for the harder part--measuring the lead in water. I did a search for 'lead test strips' and there are such things available fairly inexpensively.

Here are some sources for you to check:

https://watertestingkits.com/product/le ... ater-test/

https://www.amazon.com/Lead-Iron-Copper ... est+strips

https://www.thomassci.com/scientific-su ... est-Strips

What I don't know is whether these test strips will tell you the concentration of lead in PPB or just that they indicate a yes or no as to the presence of lead at some level. You'll have to do some reading to find out.

I hope this helps. Post again when you have more questions.

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Thank you for the help! You are correct in assuming that we have only our high school lab. How can we obtain lead from a fishing sinker? You said it can be dissolved with vinegar, but if we put vi gear into our water how would we know if it was affecting the absorption of the mustard plants? Also, we looked into the lead tests you have us, and we have determined that one of them does not tell you the amount of lead, only whether or not there is a lead presence. However, the other two we are not clear about. One idea that we had was switching from testing lead to testing copper. Lead is a more prevalent problem, and so we preferred that, however if it was copper we think we could test it with one of the strip kits. We aren’t sure what other options we have for testing the lead.
We appreciate your support!
Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Hi Sirenity,
I would like to see you use lead too because it is the heavy metal that most people worry about.

Vinegar doesn't dissolve much lead, but you do not need much to add to the water to make the lead concentration above the limit. You will have to add a measured amount of the vinegar solution to a measured amount of water (we'll work out the relative volumes later) and then measure the concentration of the lead (Pb2+).

Yes, i know the test strips I looked at seemed all to be just indicating the presence of Pb but not how much. I did a search for color reaction for lead testing and discovered a chemical called sodium rhodizonate that reacts with Pb2+ to give a purple color. The test is used in forensics to identify lead from gunshot residue: https://dps.mn.gov/divisions/bca/bca-di ... onate.aspx

https://pubs.acs.org/doi/abs/10.1021/i560110a034

Here's a source for sodium rhodizonate: https://www.flinnsci.com/sodium-rhodizonate-1-g/s0448/

And you can also buy lead acetate here: https://www.flinnsci.com/products/chemi ... d-acetate/

Your high school will probably have to order these chemicals for you, but they are not that expensive. If your school has a chemistry lab, they may already have a lead compound that you can use. You just need some water-soluble lead compound (like lead acetate or nitrate) that you can weigh accurately to make a solution of known lead concentration to use with the sodium rhodizonate to be able to measure the color reaction. The only thing i don't know is how sensitive the rhodizonate is to lead. Can you actually measure lead concentrations in the 15 ppb range this way? That is a very, very low concentration.

Well, that's the best I can do for now. You could use copper instead of lead if you want. Will mustard plants absorb copper as well as lead?

Good luck!

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hi,
Thanks for the link to the lead acetate, I think that we can use it. I’m not sure that my school will order it but since it is $10 I think my partner and I can. If we used lead acetate in our water, we don’t need to dissolve lead with vingear, right? I am a little confused about the sodium rhodizonate though. It can test for the presence of lead, but don’t we already know there is lead present? We just need to figure out how much. Does the rhodizonate change different colors based on how much lead there is, like a lead test strip? It seemed to me that it only turns violet.
Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Hi Sirenity,
That would be great if you could order lead acetate (forget about the vinegar and the lead sinker).
I understand what you mean about the rhodizonate, but I think that the color becomes darker the more lead that is present. What you can do is make a series of concentrations of lead acetate, add rhodizonate and see how much the color changes. You need to be able to see color differences in the ppm range and I don't know if rhodizonate is that sensitive.
There is a way of measuring the light absorption of a solution and this would give you a quantitative measurement of the lead concentration. The big problem with this is that it requires a somewhat expensive instrument called a spectrophotometer. There are plans for building one of these online but you would have to buy the parts and put it together yourself. It makes a great project in itself and is very useful but does require some skill with tools.
Let me know what you want to do and I will help.

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hello,
We actually have looked into the spectrophotometer before, when we originally started this project, however it is much too expensive for us to buy. If buying the parts separately and assembling them is cheaper, that’s good, but I’m not sure if we’ll have that much time to order and then figure out how to do that. We are hoping to finish conducting our experiment by the first week of January, which is approaching fast, however we have not yet worked out our procedure. So far, we’ve determined that we’re going to use lead acetate in our water. I think the rhodizonate idea might work to measure the lead though. It sounds sort of tricky to us, though, because we would have to make sure we are being accurate with the way we color code the concentrations. And like you said, we don’t know if it’s that sensitive to the ppm range.
Do you think we should take a risk and use one of the lead test strips, even though we aren’t certain of how it’s going to give us results?
One other solution we found was buying these lead kits that we could put our water in, and then mail to a lab. The lab would test our samples and send the results back to us. The lead test is meant for drinking water, but we were hoping we could use it for our purpose as well. The only problem is, it’s rather expensive. Each kit has one test tube and costs $50, and we need 3. $150 just for the kits is a bit more than we can afford.
Do you think we would be able to buy the parts of the spectrophotometer and build it ourself without too much difficulty?
Thanks, Sirenity
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hello, one more question has come up in our research that I wanted to add!
We were planning to use mustard plants in order to take the lead up from the water. However, some of our research indicates that mustard plants take up metals through the aerial parts of the plant and we are worried that the plants won’t suit our project. We are immersing the plants in lead contaminated water, and need the plants to take metal up in their roots. Do you think that mustard plants will still be useful?
Thanks! Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Wow! That's a lot of questions, Sirenity. I hope i can answer them all.

The big one is how to measure the lead concentration accurately and I'm afraid have no good answer for that unless you have a friend or family member who works in a university lab that has a spectrophotometer. I have not built one of these and I suspect that it would take more time than you have to build it, test it and get it working consistently.

The rhodizonate is a fairly cheap option. I just don't know if it is sensitive enough to show color differences in the ppm range. You can try the lead test strips, but i don't think that they give you a readout in ppm. I think they are just a yes-no indicator, although I could be wrong. You would have to call the company that makes the strips and ask them if you could use them to measure changes in lead concentration at ppm.

As to using mustard plants for removing lead from water, I would recommend that you switch to water fern, Azolla. This aquatic fern grows fast in warm water and is able to accumulate lead and other metals through its roots: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3357840/
You could set up several bowls of water containing lead acetate at various concentrations, add azolla and let it grow for a month then measure the lead concentration again using the rhodizonate reaction. If the Azolla absorbed ALL the lead then your rhodizonate or test strips would show zero lead. You will have to read the paper I sent to find out how much lead a certain number of Azolla plants can absorb in a certain length of time.

I would not spend $150 on lab test kits. You might be able to buy a used spec on ebay or Amazon for around the same amount of money.

Azolla can be purchased online from several different suppliers, one of which is our old favorite, Carolina Bio: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3357840/
However, they said the plant may not be available in winter so you would need to call them to find out whether you can get it from them.

I hope this is helpful, Sirenity, because I really want you to succeed with this project. Read some about Azolla and you will see how promising this plant is for heavy metal removal from wastewater. It will be a very good project if you can do it. Try and get some Azolla first and get it growing nicely, then worry about measuring lead. Maybe the plants can remove all the lead, in which case the test strips would be ok to use since all you need is a yes-no answer, not concentration.

Good luck!

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hi! Thank you for your support. It motivates us to continue through our project even though there are so many complications.
Our school has lead nitrate, not lead acetate, and asked if we could change our procedure to use that instead. Do you think we could use that instead?
We hope we can find a reliable used atomic absorption spectrometer that’s $500 or under, we think we can apply for the presidents grsnt to pay for it. There are several things on eBay but the details are a little sketchy so that’s the last thing we are trying to work out. I think if we don’t figure that out we might have to do the rhodizonate idea, which is good but takes much more work and not as precise.
How do we dispose of our Azolla and lead contaminated water once our project is finished? We know we can’t pour it down the drain, but do we throw the plants in the garbage? And as for the liquid, we don’t know.
We hope To conduct our experiment soon! Hopefully by January.
Thank you,
Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Hi Serenity,
You are really doing well on this lead project and I am proud of your work so far in planning it.
You are on the right track with a flame photometer as that is one of the best ways to measure concentration of elements like lead. I have no idea what a used one should cost but if you can get one that is guaranteed to work for less than $500, I think that would be a good deal.

Lead nitrate is fine to use as the pollutant. The lead ions are quite soluble and will be readily absorbed by the Azolla.

I had overlooked the disposal part of the project and it is good that you brought it up. You will not be using large amounts of lead, but the waste you generate should be disposed of properly. Will you be doing the experiments at your school? If so, then the lab manager there should have guidelines about disposing of waste containing heavy metals. You could do a google search on proper waste management and find out more information about disposal. Many of the sites I looked at focused on using Azolla to accumulate heavy metals but did not go into details about what to do with the contaminated plants afterwards. Let me know what you find out.

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Azolla Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

We aren’t conducting the experiment at our school, we plan to have the containers with the water and Azolla in my house. Can we throw the Azolla in the garbage, maybe seal the liquid in bags and throw it away too?
We are still searching for a reliable spectrometer! So far, we’ve found only this one which looks reliable, we just aren’t sure if it’s the right tool for us:
https://www.bmisurplus.com/products/833 ... ectrometer
Do you think you can verify if this is a good one? It’s a laser spectrometer and if we can use this one, we can order it and finally start the experiment.
Thanks again!
Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Hello again Sirenity,

Azolla is a good test subject as it is easy to grow in water and is known to absorb heavy metals.

I checked on the EPA site for disposal of lead and apparently it is acceptable to dispose of it in regular household trash:
1. What is the appropriate disposal method that household consumers should use for their lead-contaminated children’s products?

EPA's regulations state that wastes from households (i.e., garbage and trash) are not regulated as hazardous waste under RCRA. Household waste includes waste derived from single and multiple residences, hotels and motels, bunkhouses, ranger stations, crew quarters, campgrounds, picnic grounds, and day-use recreational areas (see 40 CFR 261.4(b)(1)). Therefore, consumers that qualify as a household may dispose of their lead-contaminated toys in the same manner that they discard ordinary household trash. Some states, however, may have more restrictive requirements, and localities may encourage consumers to dispose of such items in household hazardous waste collection events (typically sponsored by the local government); consumers should consult their state and local government for more information.

Since you will be using lead nitrate solutions for the azolla to grow in, you should ask your school's safety officer about how to dispose of the left over solutions properly. Lead persists in the environment and is toxic, so it is not advisable to pour it down the drain.

If lead appears to be too toxic to be usable safely, then you could use a solution of a copper salt such as copper sulfate or copper chloride: https://www.researchgate.net/publicatio ... r_Hyacinth

I'm not familiar with the instrument you indicated but I can recommend the Spectronic 20 which has been the lab work-horse spec for 60 years, and there are many good, working used instruments available: https://en.wikipedia.org/wiki/Spectronic_20
Here's a video that explains about the technique of spectrophotometry and specifically how to use a Spec 20: https://www.youtube.com/watch?v=Fqw1ULEOkwg

I did a search for the Candela Corporation LS-1 Laser Spectrometer that was shown in the BMI Surplus ad and there was nothing about it in Google which makes me a little suspicious. Candela Corp makes lasers, but there was no mention of a laser spectrometer, so I would stay away from this unless you can find out more about it. I know the Spec 20 can be used to measure copper ions. You will just have to search until you find a used instrument that preferably has a warranty so that you can be sure it is working. Also, spectrometers are pretty sensitive instruments and if they are packed improperly can be damaged in shipping.

Check ebay for used Spec 20's. I'm sure you will find some there. Just be extra careful in reading the description to determine that the machine has been tested and is working properly. A good ebay seller should guarantee that the instrument works as described or allow you to return it. Also, find out how well they will package the instrument to avoid damage during shipping.

Keep me posted on what you are doing.

Sybee
67ea0565731f403dadaa3fce1bb95262
Posts: 9
Joined: Mon Oct 29, 2018 6:38 pm
Occupation: Student

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by 67ea0565731f403dadaa3fce1bb95262 »

Hello,
we now have a Spec-20 in our possession! We are supposed to perform this experiment at school now, however we have discovered a problem with our Spec-20. It seemed a very reliable buyer, they allowed us to return and it was packaged very well, but it appears that the lid for where you insert your sample is broken off. Do you think we can make a makeshift lid on our own? Additionally, we do not have a cuvette for inserting our lead sample. I guess I should have researched further because I didn't realize I would need one. They seem rather expensive to buy, so I am hoping that our school has one. But, we do need to figure out how to fix the lid for the sample compartment on our own, because it doesn't seem like we have enough time to pay the return shipping back and then find a new machine to buy.
Thank you,
Sirenity
SciB
Expert
Posts: 2066
Joined: Fri Feb 01, 2013 7:00 am
Occupation: Retired molecular biologist, university researcher and teacher
Project Question: I wish to join Scibuddies to be able to help students achieve the best science project possible and to understand the science behind it.
Project Due Date: n/a
Project Status: Not applicable

Re: Phytoremediation Science Project: The Effect of Mustard Plants on Lead Concentration in Water

Post by SciB »

Hi Sirenity,

Wow, you have made good progress and are learning a lot about the real world of science!

You can make a lid for the cuvet holder using aluminum foil which is opaque. You can also use the machine in a room with the lights off to prevent stray light from entering the cuvet chamber.

As for the cuvets to use in measuring sample absorbance, you can probably use plain glass test tubes that are small enough to fit into the chamber. The Spec20 I used had round sample tubes that were about 10 cm long and maybe 12 mm in diameter. If your school lab has some small test tubes, you can try them and see if they fit. They should be snug but not too tight.

The cuvets that are made for the Spec20 are manufactured to higher standards than test tubes so they are as nearly identical as possible. This is necessary when comparing readings. But you can compensate for glass differences in your test tubes by zeroing the machine with water each time before reading your sample.

See what tubes you have, try them and let me know what happens.

Sybee
Locked

Return to “Grades 9-12: Life, Earth, and Social Sciences”