Ocean Iron Fertilization Project

[oriculumn]

Hi! My teacher just assigned science fair projects, and I want to do mine on Ocean Iron Fertilization. I want to see how the amount of iron affects the amount of CO2, and how the addition of iron will affect the water for marine life.

I am unsure of what the source of iron is. Is it ferrous sulfate or something else? And where can I get this source of iron? Also, how much iron is added for about 1 liter of ocean water?

As for getting the ocean water, how can I make sure that the phytoplankton survive long enough to conduct the experiment? I was hoping to do a study over the course of 2 weeks or more depending on the lifespan of the phytoplankton. The Gulf of Mexico is several hours away from where I live. We don't have a pet store in my town, so nobody really knows about taking care of marine organisms.

Also, what seems to be a good container to use for the experiment? Do I need something large like a fish tank, or could I use something small like a beaker?

And where can I conduct this experiment? Do I need to work outdoors, or could I simulate the ocean environment indoors? What can I do to simulate the ocean environment on a smaller scale?

I'm sorry if it seems like so much, but I couldn't find too much information about ocean iron fertilization. Any help would be greatly appreciated!

[deleted-71490]

You have selected a very interesting science fair project. Here some web sites will give you a head start in planning the project.
[PDF]

2002 Fall Meeting OS22E MCC: 104 Tuesday 1330h Presiding:
File Format: PDF/Adobe Acrobat - View as HTML
integrated over time since the initial Fe amendment in-. dicated a >2 fold enhancement of export ... Eight open ocean iron fertilization experiments have ...
www.agu.org/meetings/fm02/fm02-pdf/fm02_OS22E.pdf - Similar pages

[PDF]
, ; , ; ,
File Format: PDF/Adobe Acrobat - View as HTML
Ocean with iron was carried out. Two areas were fertil-. ized, one at about 55 degree S, ..... integrated over time since the initial Fe amendment in- ...
www.agu.org/meetings/fm02/fm02-pdf/fm02_OS22D.pdf - Similar pages

AmeriScan: February 19, 2002
Feb 19, 2002 ... The purpose of SOFeX, the Southern Ocean iron (Fe) experiment, is to test the ... Under the direction of MBARI's Ken Johnson, a ship pumped an iron .... to try to add this controversial amendment on the Senate floor. ...
www.ens-newswire.com/ens/feb2002/2002-02-19-09.asp - 58k - Cached - Similar pages

Climos
The IOC amendment addresses the scientific basis behind the CBD recommendations, ... A Statement on Ocean Iron Fertilization (OIF) by the IOC Ad-hoc ...
www.climos.com/climosblog/index.php?s=coastal - 40k - Cached - Similar pages

40 ANNUAL NUCLEAR AND SPACE RADIATION EFFECTS CONFERENCE NSREC 2003
temporal sampling of the ocean and its inhabit-. ants. MBARI is located in Moss Landing, Cali- .... outstanding collection of cast iron and terra ...... posed amendment shall be publicized in the IEEE TNS or Medical Imag- ...
ewh.ieee.org/soc/nps/newsletter_nps0603_final.pdf - Similar pages

Sea Technology Back Issues | Archives from 200407 | HighBeam Research
MBARI Maximizes the Use of the Dorado AUV using Brooke Ocean .... D.C., to review New England's management plan for groundfish, known as Amendment 13. ...
http://www.highbeam.com/Sea+Technology/ ... ate=200407 - 75k - Cached - Similar pages

[PDF]
Annual Report Monterey Bay Aquarium Research Institute
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new technologies developed at MBARI into ocean observ-. ing systems where they can have much wider ...... tivity and biogenic silica export to iron enrichment in the ...... and Other Postretirement Plans — an amendment of FASB Statement ...
http://www.mbari.org/news/publications/ ... lowres.pdf - Similar pages

Good luck,

Matthew W. Mulanax

[oriculumn]

Hi! Thanks for sending me all the information!

So far, I know that ferrous sulfate is used, and 1.74E-4g of ferrous sulfate is used for every square cm.

BUT I still can't figure out how to create an ocean environment model. Will I need to include sand? And I'm still unsure about the size of the sample. I'm not sure if I need a fish tank or if I can use a beaker. Please help!

[deleted-71447]

Hi oriculumn,
Congratulations on choosing a very important and timely topic. There is a lot of leeway in the experimental design for this proposed project. Before you worry too much about the design, have you developed a specific scientific question and a hypothesis? I see that you have this question: "I want to see how the amount of iron affects the amount of CO2, and how the addition of iron will affect the water for marine life." but you will need to be much more specific. Coming up with your scientific question should be your first step, and it will help you to understand how to best design the experiment to address your specific interests.

A very good way to develop a specific question is to to read as much as you can about the topic, and to identify a narrow issue that remains a topic of debate, or some issue that might have been overlooked. I would recommend starting with a broad literature review to identify one "hot" topic of debate about ocean iron fertilization that interests you the most, and then more focused literature review on that subtopic to identify a feasible experiment.

Good luck!
Chris

[oriculumn]

Thanks for replying, but I'm not sure how much more specific I need to be! Isn't that my scientific question already? I keep reading article after article about iron fertlization, but I always get either iron dust or ferrous sulphate. NO SPECIFICS! The most specific thing I've found was "A circle of 10km radius will be fertilizaed twice with 20 tonnes of dissolved ferrous sulphate acified with HCl to yield a concentration of about 2 nmol Fe/L which is still well below iron concentrations commonly measured in coastal waters. The ferrous sulphate we will use is sold in gardening shops to improve lawns and employed by sewage treatment plants to remove phosphate, so is free of toxic contaminants."

Sold in gardening shops? There are no specifics! What percentage of the fertilizer is ferrous sulphate? How the heck will I know about a concentration of 2 nmol Fe/L?! I keep researching and get NOTHING of use. There's always different sources of iron, but I'm not sure which I should use! If I were to use different sources of iron (i.e. iron dust, Ironite, Copperas...), do I just write down the percent Fe is in there or what? No one is helping me here!

I want to enter the dang science fair, but I can't if I don't do this project ASAP! You keep telling me to research, but there are no specifics! And I don't even know what I should test that I am ABLE to test! My question stands as is, and I hypothesized that with increasing amounts of iron, there will be less CO2 in the atmosphere and be bad effects to the water and marine life. I plan to use some source of ferrous sulphate and acify it with HCl to yield a concentration of about 2nmol of Fe/L or close to it! With the addition of the acid, it may lower the pH of the water, and cause disastrous results to marine life. I DON'T KNOW WHAT SOURCE OF FERROUS SULPHATE TO USE! THERE ARE NO SPECIFICS!

I'm getting really frustrated with redundant research that turns up the same results! Just telling me to research the same info incessantly and receiving no helpful information is like telling me in order to live I have to stay alive. It's vague, and unhelpful! If someone's done this project already, could you please HELP ME?!

I'm sorry if I'm sounding extremely ungrateful, but I'm not getting any help here, and I keep stressing out!

[deleted-71490]

It sounds like you want to test the difference in CO2 capture between sea water and sea water amended with 2 nmole Fe/liter.
The label on ferrous sulfate from the garden supply section will contain the percent iron or ferrous sulfate. Based on those numbers you can calculate the amount of ferrous sulfate required. Your science teacher can help with the calculations.

Matt Mlanax

[oriculumn]

*sarcastic* No, really? I didn't mention that before? *end sarcasm* Seriously, wasn't that clearly implied from my first post?

Also, it's pretty obvious that labels will give percentages, but THAT WAS NOT WHAT I WAS ASKING. DO YOU EVEN UNDERSTAND THE DARN POST?! When I asked about percentages, I meant to use for the ocean; like, what percentage ferrous sulfate fertilizer is used! DO YOU EVEN UNDERSTAND ANYTHING ABOUT OCEAN IRON FERTILIZATION?!

Also, when it says, "...fertilized twice with 20 tonnes of dissolved ferrous sulphate..." Could you at least answer what is meant by "twice"? Does it mean fertilized once, and then again several weeks later? or what? Cuz I keep researching and turn up NOTHING.

I try to be nice, but you all are so frustrating!

[donnahardy2]

Hi,

We can try to help you get started on your project; however, we do need to understand what your question and hypothesis is. Here is some information about ferrous sulfate and fertilizing that should help.

Fertilization is done periodically, so the authors of the paper you read added ferrous sulfate to the ocean at two different times. If you read the rest of the paper, you should be able to find out what the time interval was between fertilization

Ferrous sulfate (FeSO4) is sold in gardening shops, at least in areas like mine where the soil is alkaline, in 5 pound boxes. I believe is about 98% pure. Ferrous sulfate has a molecular weight of 152 (Fe 56, S 32, O 16). If you weigh out 155 grams of ferrous sulfate (152/.98) and dissolve it in one liter of dilute hydrochloric acid you will have a solution that has a concentration of 1 mole per liter. The authors of the paper fertilized the ocean at a rate of 2 nanomoles per liter of ocean water. To reproduce this experiment, you would use 1 milliliter of your 1 mole per liter solution in 100,000 milliliters of ocean water.

Have you had chemistry? If so, this should make sense, but if you have questions, let us know. If you get some ferrous sulfate at a garden supply store, let us know the concentration and purify. It is available in liquid form too, but if you get this form, make sure there is nothing else in the product besides ferrous sulfate.

Now, please let us know more about your research. Do you know what the function of the iron in plants is? Why is the pH of water/soil important for iron utilization by plants? Are you going to use fresh water or ocean water for your experiment? If you are using a natural source of water, do you have a method for testing for the iron concentration present in the sample? What is the significance of your project? If you have your experimental protocol written up, it might be helpful to post it so we can see what you are thinking about doing.

I hope this helps. We do want you to have a successful project.

Donna Hardy

[deleted-71447]

oriculumn,
We all understand that it can be very frustrating to try to convey complex ideas, but even in the face of these frustrations it is important to use respectful language in these forums. Please avoid sarcasm and less-than-complimentary personal comments.

It's great that you have read some literature on the topic. If you have specific questions about a procedure in a particular paper, please post the authors' names, article titles, date of publication, journal, etc so that we can assist.

As Donna said, we need to understand your hypothesis to be able to help you with project design issues.

I hypothesized that with increasing amounts of iron, there will be less CO2 in the atmosphere and be bad effects to the water and marine life.

Can you tell us, for example, what type of "bad effects" you would like to study, or what type of "marine life" you would like to study? Will it be feasible for you, in the time you have, to study both the topic of CO2 update and the topic of adverse biological effects of iron fertilization? If you don't know the answers to these questions, that's fine. We can work with you to iron out these details.

Looking forward to hearing more,
Chris

[oriculumn]

Okay, I decided to change my project around a bit. Instead of acifying the ferrous sulphate with HCl, I think I'll just dilute the ferrous sulphate with water, probably to different concentrations like .1M, .5M, 1M, 2M, and 5M. The thing is that the package of ferrous sulphate is Copperas brand and it said something like 19% Iron and 30% sulphate though the ingredients list says Ferrous Sulphate. So, I'm confused. How will I dilute this to the different concentrations?

I've mentioned it before: I am using ocean water. I am not using plants, I'm using phytoplankton.

I plan to use 1000mL beakers for this experiment. Is that alright or do I need something larger?

When I looked at the ocean water I've collected through a microscope, there were no phytoplankton unfortunately, so I had to order some online. How will I know that the phytoplankton is alive? Will it move when I look through a microscope?

I don't know how to test the iron concentration of the ocean water.

I don't know what to use to measure the amount of atmospheric CO2 before and after adding the iron to the ocean water with phytoplankton. Do you have any suggestions? Is there a device that I could order that could measure the amount of atmospheric CO2?

How can I make sure that the phytoplankton grew after the addition of iron?

Okay, to be more specific, I expected the "bad effects" to be a change in the pH to the point that some marine life (fish, crustacean, algae, marine plants, etc) will no longer survive, a change in ocean salinity, a change in dissolved oxygen, and a change in the number of phosphates.

I'm not sure if I'll have time to do more research with a few family problems currently going on. I really need help. Please. Thank you!

[donnahardy2]

Hi Oriculum,

Here are answers to your questions, and some suggestions:

1. Your ferrous sulfate contains 19% Fe, or 19 grams of Fe per 100 grams of product, or 19 mg of Fe per 100 mg of product.

1 mM Fe x 56 mg Fe x 100 mg product = 294 mg product
1 mM Fe 19 mg Fe

This is a balanced equation that shows how much of the ferrous sulfate (product) you need to weigh out to get 1 mM of Fe. You did not answer my question to let me know whether or not you have had chemistry, but you need to understand this for your project, so let me know if you need additional explanation. The result shows that you will weigh out 294 mg of the ferrous sulfate to obtain 1 mM of Fe. If you dissolve 1 mM of Fe in 1 ml of water, the concentration will be 1 mM/mL; if you dissolve 1 mM of Fe in 1 liter (1000 ml) of water, the concentration will be 1000 nanomoles per liter. So, if you dissolve 294 milligrams of the ferrous sulfate in 1 liter of water, you would use 2 ml to of solution added to the 1000 ml beaker of ocean water to match the concentration used in the original reference you cited (2 ng/liter). You don’t want to make a 1 M (100,000,000 nanomole) solution otherwise you would be studying the acute toxicity of iron on phytoplankton.

I recommend that you make the 1000 nanomole solution and add between 0 and 10 ml of this to each 1000 ml beaker, or something similar. Does this make sense to you? Do you have access to a balance that can weigh 294 mg? If not, let me know the smallest amount you can weigh, and I’ll recalculate this for you.

2. If you collected wild ocean water, there were probably phytoplankton present that would eventually grow, but it’s fine that you ordered some. Just make sure you add an equal amount to each beaker.

3. Phytoplankton numbers are measured by letting samples settle in a chamber and then counting the microalgae under a microscope. Please read the protocol below very carefully to see if you can obtain the equipment (settling chamber, Lugol’s solution, glass slides and coverslips. Please notice that doing phytoplankton counts requires sample volumes of up to 48 ml, so if your original sample is 1000 ml, you will be using a significant percentage of the volume if you need to test too many 48 ml samples. If you will be adding enough phytoplankton to each sample so you will only have to test 8 ml samples, then the 1000 ml volume will be enough.


http://www.evergladesplan.org/pm/recove ... ankton.pdf

http://www.eman-rese.ca/eman/ecotools/p ... n/lab.html

4. A chemical called dipyridyl dissolved in 50% ethanol will combine with FeII to make a red complex. I have used this as a qualitative test for Fe II, but I don’t know if it would be sensitive enough to assay for Fe II in ocean water. Do you have access to a spectrophotometer and cuvettes? Do you have any dipyridyl available? If you do, I will try to find more information on this for you. You would mix known concentrations of Fe II with the dipyridyl and measure the absorbance at about 550 nm to make a standard curve (concentration of Fe on x-axis, absorbance on y-axis). Your project would be acceptable if you skipped this step, but this would be a nice addition if you could do it.

5. Are you sure you need to measure atmospheric CO2? Are you doing this experiment in an enclosed environment? Would you please let us know what your question and hypothesis are? I gather that you will be measuring the growth of phytoplankton in beakers of water with different concentrations of iron. If the phytoplankton grow, they will use CO2 from the atmosphere and grow on their own, so you don’t need to measure atmospheric CO2. Your independent variable is iron concentration in the water; your dependent variable will be the numbers of phytoplankton. The CO2 in the atmosphere, composition of the ocean water, temperature, and sunlight will all be identical (controlled), so that your results will measure the effect of changing the iron concentration. I don’t think it would be possible to change the salinity, unless the water evaporates. The dissolved CO2, phosphate, and oxygen in the water and the pH of the sample could change, however, and these are dependent variables that could be measured in addition to the numbers of phytoplankton. I am concerned that you are trying to do too much in one experiment, especially since you are short of time. Why don’t you concentrate on just measuring the numbers of phytoplankton? This will be a perfectly complete project with quantitative results. If, however, you do decide you need to measure more dependent variables, let me know and I’ll try to recommend a suitable method.

Please do try to find the time to back and read all of your references again, and look up additional background information for your project. This will be an excellent project!


Donna Hardy

[oriculumn]

Thank you! Thank you! Thank you so much for clearing things up for me!

But yes, I have taken Chemistry, but over a year ago, so I can't recall everything, but I understand what you've explained. And I do have access to a balance that can measure 294mg. I'll go with your recommendation.

As for the equal amounts of phytoplankton, is it alright to measure by volume? or should I go by mass?

I'm not sure if I can obtain Lugol's solution, but I'll reread the articles you listed in case I've overlooked other things.

I do have access to spectrophotometers and cuvettes! But I'm not sure about the dipyridyl... I'll check with my teachers if they have any.

Well, the main idea of my project was to find out if ocean iron fertilization really did work in reducing atmospheric CO2, and according to research, it does... BUT I wanted to find out more specifically which concentration of iron works best, and if there will be any side effects that come with the addition of iron AND if the side effects vary with different iron concentrations. I really enjoy doing projects that deal with global warming or the greenhouse effect or basically environmental projects.

I will be working in an enclosed environment actually. Is that alright?

So, if the phytoplankton were to grow larger in one sample than the other samples, does that mean that more CO2 is absorbed?

I'm also afraid that my plan is too ambitious, but my teacher has these "kits" that I could use to measure the amount of phosphates and dissolved oxygen. I'm afraid she doesn't have a "kit" to measure the amount of dissolved CO2. I really would like to measure more dependent variables. I'll continue reading more on the subject!

Thank you so very much again!

[donnahardy2]

Hi Oriculum,

You are more than welcome!

Since identification of the phytoplankton species is not important for your project, you could probably use volume of phytoplankton to measure this dependent variable. You won’t need to look under the microscope and count each individual plant. If you take a sample of water and let it settle in a centrifuge tube, or other long thin tube with a bottom that is calibrated for volume, you could measure the volume of the algae. It would be quicker if you could centrifuge a sample and then measure the volume of the phytoplankton pellet. This method seems like it would be easier than measuring the weight of wet algae. It would be good if you could do a trial sample and see if you run into any difficulties in getting a measurement.

Thanks for explaining your project. Since the subject is really about carbon dioxide and you will be working in an enclosed environment, then you do need to measure the concentration of carbon dioxide. However, it is difficult to accurately measure carbon dioxide in air without a CO2 meter or specialized laboratory equipment. Personal CO2 meters cost $100 to $700, so are expensive. Or, you would need to have access to a laboratory that does this type of testing and permission to use their equipment. Its fine to work in an enclosed environment because this will allow you to maintain the atmosphere, but you would need to measure what the concentration is so you can report this. You will be keeping the amount of carbon dioxide controlled for this experiment, so you could get by with just one or two measurements (one at the beginning and end). Can you borrow a CO2 meter? Or, can you call a local environmental lab and ask if they will help you with a couple of samples? If these options are not possible, however, your project will still be a complete project. If you can’t do a CO2 measurement, you might want to work in the open air and use the public information CO2 measurement levels from the closest testing station to you, for example:

http://www.esrl.noaa.gov/gmd/ccgg/trend ... a_mlo.html

The amount of CO2 absorbed will be proportional to the volume/mass of the phytoplankton, so you can use literature sources to estimate the quantity of CO2 consumed. This will be an indirect measurement, but still scientifically valid. You can assume that the containers with more phytoplankton growth represent higher CO2 consumption.

I have a question about your experimental protocol. The ocean moves around, so the water is continually oxygenated, at least near the surface. Are you going to have any mixing during the experiment, or at least a couple of tides a day? Will you have lights 24 hours a day, or just during daylight hours? Plants consume CO2 and produce oxygen with light, but will consume oxygen and produce CO2 with respiration at night. If the phytoplankton grow to very high levels, then oxygen could become depleted, at least while it is dark. So the dissolved oxygen test might be a good dependent variable to include with this project. You won’t be adding animals to your beakers, for this experiment, but animals require certain levels of oxygen for survival, so it would significant if the oxygen became depleted in your samples. I’m not sure about the phosphate levels. Phosphate would probably be one of the limiting nutrients in your sample, unless you collected polluted ocean water, so the results of this analyte would not add that much to your project. Do you have a method for measuring pH? This is a critical factor for survival of animal species, so it would be significant if the pH of the sample changed during your study.

It’s excellent that you are thinking about the details of your experiment. Let us know if you have any other questions.

Donna Hardy

[oriculumn]

Thanks again for all the help!

As for the CO2 meter, I'll have to ask around. If I can't get a hold of one, I'll probably just have to use the indirect measurement based on phytoplankton growth. In order to tell if the phytoplankton grew, would centrifuging a small sample work? Or is there a more proper method to measure phytoplankton growth?

I probably will be stirring the samples a couple times a day. Also, I'll more than likely have the experiment have light only during daylight hours. Would this setting be best to simulate the ocean environment?

As for measuring pH, I'm not sure which method would be best for this experiment. Do you have any suggestions?

Thanks so much again!

[oriculumn]

Oh, and I also have a few more questions:

1.) How much phytoplankton should I add? 100mL? 50mL? Do I add it after pouring 1L of ocean water in the beaker?

2.) How will I test for phytoplankton growth? Do I use a centrifuge for this too?

3.) Is there a correlation between amount of CO2 absorbed and phytoplankton growth? For example, if more CO2 is absorbed, the phytoplankton will grow more?

4.) I'm still wondering about the most efficient way to test pH. I shall test the original pH of each sample, and then record the pH after each day. What would be the best way to test for pH?

Please help! Thanks!

[donnahardy2]

Hi Oriculum,

You have good questions.

1. I assume you have received an order for phytoplankton that has been actively growing before it was shipped to you. The algae will have to equilibrate for a day or two, and then start growing again in your ocean water samples. Phytoplankton will grow logarithmically within a short time if nutrients are available, but I'm not sure what the doubling time will be. A 1 ml sample in 1 liter would give you a 1:1000 dilution and a 10 ml sample diluted into 1 liter will give you a 1:100 dilution. If you have at least a week or two to conduct your experiment, I assume that this would give you a good starting number and there should be a difference in the growth curves with different iron concentrations. If you add a higher volume of sample, there will be fewer generations of phytoplankton to measure during your experiment. I have been looking for a reference that gives the generation time for phytoplankton, but I have not found one yet. This would be something good to look for.

2. Yes, why don't you try a centrifuge test with your sample and see if you can measure the volume with the equipment you have available? If you can measure phytoplankton volume, then you won't have to do the more time-consuming microscope counting project. Did the company that you ordered the sample from give any information about the numbers of phytoplankton in the sample? If not, call or e-mail the company and ask.

3. Yes, there should be a correlation between the mass of phytoplankton and the amount of CO2 consumed. This is another reference that you need to find (I haven't tried looking for this yet). But go ahead and proceed with your experiment, and I'm sure we'll find a conversion number to use before you have to turn in your project. This will be valid if you use a reference from the scientific literature, since you won't be able to measure CO2 directly.

4. The easiest way to check pH of water samples is with pH paper. You could check the pH on day one, and periodically during the experiment. It's difficult to measure the pH of water with a pH electrode, unless you have a special one that is designed for use with samples with low buffering capacity. pH paper would be good enough for your experiment. Do you have pH paper available?

Donna Hardy

[oriculumn]

Thank you for all the information!

Unfortunately, the company that sold me the phytoplankton did not give any information about the numbers of phytoplankton in the sample, and after emailing the company, I still haven't received a reply.

I'm not sure if I have pH paper available, but I will ask my teachers ASAP.

Thank you so much again!

[donnahardy2]

Hi Oriculum,

If you make a 1:100 dilution of the phytoplankton, your sample will be able to multiply for about 6.5 generations; if you make a 1:1000 dilution, the sample will be able to multiply for 10 generations, if the nutrients in your original sample are similar to the phytoplankton culture. I recommend trying the 1:1000 dilution.

Donna Hardy

[oriculumn]

Oh, my Biology teacher told me that phytoplankton need oxygen to survive and suggested that I use an oxygen pump (like for fishtanks) for each sample.

She also said to use empty plastic bottles filled with 1L seawater, phytoplankton, and then add iron to it. Punch two holes into each cap of each plastic bottle, and then stick some tubing into one of the holes that'll connect the oxygen pump to each bottle.

Is this a good plan to follow?

Wouldn't this affect the dissolved oxygen data?

[donnahardy2]

Hi,

Your biology teacher's suggestion to add oxygen to each container is excellent. The phytoplankton will grow much better, and the mixing that occurs will be similar to the natural mixing that occurs with the tides in coastal waters. The extra oxygen will affect the dissolved oxygen levels in the water samples, but since you will be setting up all of the bottles the same way, this will be a controlled parameter. The only factor that you want to vary in your samples if the iron concentration. If you will be measuring oxygen levels, then oxygen level is one of your dependent variables, along with the phytoplankton mass. You will just measure and record your results.

You topic is very timely. Here is an article on phytoplankton and global warming:

http://earthobservatory.nasa.gov/IOTD/view.php?id=7187

Donna Hardy

[oriculumn]

Oh, thank you so much!

I've run into another problem. I read through the instructions from the phosphate and dissolved oxygen kits used to measure the amount of phosphates and dissolved oxygen. Basically, I'll be needing about 40mL of water from each bottle for every time I want to test for phosphate and dissolved oxygen, and once the chemicals from the kits are used, I can't put the water back into the bottle; it needs to be disposed. I'm not sure what I can do about it now.

Would this affect my data? According to my calculations, if I were to continue with the daily tests for 2 weeks, I'll use up 560mL of water from each bottle.

What can I do to keep a consistent project? Should I just continue with daily tests despite the reducing amount of water in each bottle? or is there an alternative to testing for phosphates and dissolved oxygen?

[donnahardy2]

Hi,

I don't think it would be a good idea to use up half of your sample in testing. How much water are you going to remove for the phytoplankton measurement? I think you need to do daily testing on the phytoplankton levels, but perhaps for the oxygen and phosphate analysis, you could take a measurement at time zero, 7 days, and 14 days. That would give you an overview of the results without using up a significant volume of your sample.

Have you done a trial run on phytoplankton measurement? I recommend doing this before you set up your experiment. I think you were going to take a sample of water and centrifuge it and measure the volume of the phytoplankton pellet. Is this correct?

Donna Hardy

[oriculumn]

Hi,

I was thinking of taking 5mL of each sample for phytoplankton measurement. Would that be enough?

I am about to do the trial run on phytoplankton measurement. Yes, I plan to take 5mL of each water sample and centrifuge it, and then measure the volume of phytoplankton pellet.

Thank you so much!

[donnahardy2]

Hi,

Why don't you do a trial run on 5 ml and see if that is enough? You might not get enough to measure at first, but it would probably be plenty for later samples. If it takes a larger volume for the phytoplanton measurements, you might have to make adjustments in the frequency of your sampling, or the initial water volume.

Donna Hardy

[oriculumn]

Hello! I'm now on the calculation portion of my experiment. I can't exactly find the correlation between CO2 absorption and phytoplankton growth. Could I please get some help with this?

Also, could anyone suggest any extra calculations I can do to improve my project? I've only measured pH, phosphate, and dissolved oxygen content. So far, it's basically been the same. The pH became slightly acidic. There was no difference in phosphate, and some samples lowered the dissolved oxygen content.

[donnahardy2]

Hi Oriculum,

I'm sorry I suggested that there was a correlation between CO2 consumption and phytoplankton growth. There is, of course, because phytoplankton use CO2 as a carbon source to grow, but I can't find a paper where this is quantitated. Why don't you send an e-mail message to the author of the original paper and ask this specific question? Here's another website with author contact information. I think you need a real subject matter expert for this part of the question.

http://www.pubmedcentral.nih.gov/articl ... id=1913777

Don't worry about your project write up if you don't get an answer. If your phytoplankton increased in volume or numbers, you can still conclude that that more CO2 was consumed, because it is a known scientific fact that plants use CO2 for growth.

However, it sounds like you have some excellent results. You can plot the pH, phosphate, and dissolved oxygen. It's OK that there's no change. Data is data, and you can plot those results. You should have seen an increase in the phytoplankton volume. What did you observe with the phytoplankton results?

Donna Hardy

[oriculumn]

Well, what had actually resulted was an increase in the amount of phytoplankton over the course of one week. Afterward, the amount of phytoplankton began to decrease. This probably has something to do with how when phytoplankton decompose aerobically, they use oxygen and release CO2, which lowers the pH of the water. CO2 is probably being released rather than sinking to the bottom since the vessel used (plastic bottle) is not deep enough or because of the decrease in water volume after each centrifuge test.

The amount of phytoplankton unfortunately was too small to actually record the volume. If were to have used larger water samples to centrifuge, I would have run out of water for each sample. Is there another way to calculate the volume of phytoplankton? or should I just observe any general growth or decline in phytoplankton amount?

I looked over my results again, and I realized that I had made a mistake with the phosphates. The amount of phosphate actually increased over the course of two weeks. I'm not sure why though. I couldn't really find anything related to an increase in phosphates in my research. Could you explain or send me a link about this?

I'm assuming the fluctuations in dissolved oxygen was due to the differences in amount of oxygen pumped into each bottle. Sometimes, when I would check on the experiment, no oxygen would be pumping into the bottle. This could be one reason for the fluctuations, but are there any other reasons?

Also, I'm not sure how I should display all of my phytoplankton data. Should I display one graph for each day, displaying an increase or decrease in phytoplankton amount depending on concentration? or Should I display one graph for each concentration of iron, displaying an increase and/or decrease in phytoplankton amount per day? Which would be best?

Since I did 3 simultaneous trials, should I average out this data for the graphs? or should I separate them?
or if there's a better way, could you give me suggestions?

[donnahardy2]

Hi Oriculum,

If you couldn't measure the volume of the phytoplankton then do include as much information as you can, but be sure and mention that you would have made this measurement quantitative if you could have. Do you still have the samples available so you could at least measure the volume of each concentration of iron at the end of the experiment? You could use the whole sample if you needed to compare results if needed. If not, then just make the best qualitative description that you can.

How much did the phosphate increase? What kind of containers were you using? I would have guessed that the phytoplankton would have used phosphate and incorporated it into the cells. Did you filter out the phytoplankton before you measured phosphate in the water, or were the phytoplankton part of the phosphate samples? What method of phosphate analysis were you using? This is an exceptionally interesting result, and I'm sure there is a good explanation that will make your write up fascinating, but a little more information is needed to figure this one out.

You need to find out why the phytoplankton numbers decreased. One possibility is that phytoplankton will undergo autolysis (breaking down) when they are under stress. Here’s a reference that includes a little information on this. If you are sure that the phytoplankton disappeared, then this would explain the phosphate increase also, because the cells would release all of the cell components, including the phosphate that is part of DNA and molecules used for energy transfer like ATP. If you use this explanation, you will need to explain why your phytoplankton were so stressed.

http://www.sciencedirect.com/science?_o ... 5cc78df9da

Here’s another reference that includes information on phytoplankton autolysis:

http://www.sciencedirect.com/science?_o ... 29601a1f44

I'm sure the oxygen levels were a reflection of the aeration of the sample, and you would expect it to decrease if the pumps stopped working. This would definitely affect your results if it happened frequently.

For your data, it would be best to put everything on one graph with the x axis containing:
1. estimate of phytoplankton numbers.
2. oxygen levels
3. phosphate levels


The y axis would be time.
Use a different color line for every concentration of iron and the control. To make it clear make all 3 replicates similar and label each line clearly. If the graph looks too complicated, then average the 3 replicate results so you have just one line for each concentration of iron. Do a rough draft and show it to someone who is not familiar with your project and see if understand what happened. The science fair judges will spend a minute or two looking at your results, and you want your presentation to be very clear and concise. This graph is the most important part of your project.

You have some excellent results and your presentation of the results and analysis and discussion of the data could make this an exceptional project. Do you need any additional information?

Donna Hardy

[oriculumn]

Thank you so much! And yes, I will be needing additional information.

What sort of qualitative description could I use for the amount of phytoplankton?

Well, on Day 0, the phosphate was a 0.3ppm. By Day 14, some had increased to about 1.5ppm. I was using plastic 1L bottles in this experiment. I did not filter out the phytoplankton when taking the phosphate measurement. I was using a LaMotte Phosphate test kit to test for phosphates. So, what could have caused this increase?

I'll research more on what could have caused the stress on the phytoplankton.

I got lost on the explanation of the graph. So, I should put everything (phytoplankton, pH, oxygen levels, phosphate levels) on the x-axis? How do I do that? Wouldn't the graph look quite cluttered with all the different lines?
So, in the end it'll be one graph per sample? I'm still very confused. Sorry.

[donnahardy2]

Hi Oriculum,

You are right; putting everything on one graph will be too cluttered. Here is an example of a line graph, which will work with your data:

http://www.ais.msstate.edu/AEE/Tutorial/pdfs/line.pdf

You should put each data set on one graph, so you will have one graph for pH, one for phosphate, and one for oxygen. Look at the example, and label the graph clearly. For example, for the pH chart, the title will be "pH change"
the y axis will be "pH," the x axis will be time. You will have one line for each concentration of iron. You should have a key identifying the concentration of iron (e.g. use green (or circles) for the control, red (or squares) for the lowest concentration of iron, etc.) You will have one line for the control, and one for each concentration of iron. This will unclutter the data and communicate your results clearly.

Now for the phytoplankton. Your results are qualitative, but you could make another line graph, and label the graph "Phytoplankton population estimation," label the y axis "approximate phytoplankton numbers, with an arrow pointing up". Then mark in the approximate population for every time point day, using the same scheme to identify you used for the other graphs. Anyone looking at your 4 graphs will be able to sort out the results for each sample. Does this help, or do you need more help on graphing?

Now a question about the disappearance of the phytoplankton. Did the phytoplankton disappear from the control sample and from each concentration of iron? If so, then they may have starved to death due the lack of a critical nutrient, possibly nitrogen or silica. Nitrogen is used to manufacture proteins and silica is used for the support structure of phytoplankton, kind of like human bones. Or, maybe something else was growing in the sample that may have been toxic. For example, here is a website that summarizes a PhD thesis done on the interaction and competition of various marine microorganisms. The term used to describe this is allelopathy, or inhibition of plant growth due to biomolecules released by other organisms.

http://www.fimr.fi/en/ajankohtaista/mtl ... sertation/

The phytoplankton had enough oxygen, and plenty of light, so these parameters were not limiting the growth.

Another possibility. I think you said that you collected the samples some time before you started the experiment, so something else may have been growing in the samples and using the nutrients before you added the phytoplankton. Was there any difference between the no-iron control sample and the samples with added iron? If there was some growth in the controls, then perhaps the concentration of iron was too high.

The increase in phosphate concentration supports the theory that the increase in phosphate was due to the autolysis (death) of the phytoplankton. Did the phytoplankton disappear shortly after you started the experiment, or did they die gradually over several days. What difference in the samples did you see that indicated the phytoplankton were disappearing?

Since adding iron to your samples did not increase the growth of phytoplankton, as you had proposed in your hypothesis, you should include an analysis that would explain what happened, and why your phytoplankton did not grow. You can add a short paragraph to state what you would do differently in the next experiment to prove your original hypothesis.

Does this help?

Donna Hardy