Ocean acidification experiment

[oceanman1]

Hi,
Im planning on doing the ocean acidification project on your website: swimming in acid for my 9th grade oceanogrphy class. However when I presented the procedure to my teacher he said topic was good but experiment seems too simple. Our scoring rubric gives more points for an experiment with multiple stages of observation/recording data. I compared your experiment with a similar one done by Epoca. Both want containers covered..yours says not to uncover for one month or co2 escapes; their experiment has you checking ph daily...i dont understand the difference. Is the Epoca experiment valid then? Is there a way to make this experiment "more"? I was thinking of putting containers in refrigerator and then comparing them to room temperature containers but then arent I using two variables ? Also both experiments call for a ph meter, can i get by with using ph strips?, trying to cut some cost. Any help or direction would be appreciated.
Oceanman1

[deleted-140482]

Hi Oceanman,

While the Epoca experiment and the Science Buddies experiment have slightly different procedures, that doesn't mean one of them is more valid than the other. The Science Buddies experiment is concerned that CO2 will escape when you open the containers, but as long as you treat each container equally (i.e. each container is opened the same number of times for the same amount of time) you will be controlling for this. The most important thing is to carefully document all of the details of your experiment, including when and for how long you opened containers.

In order to make your topic have multiple stages of observation/recording data, I recommend a couple of things:
1) Don't just wait until the end of the month to weigh your shells. You could weigh your shells every week, for example, and then put them back into your ocean water. This way, you could graph the change in weight over time, instead of just having a beginning and ending value.
2) Each time you open a container, measure the pH to see if it has changed.
3) Consider using ocean water with a range of pH instead of just regular ocean water and pH 7.5 water. This will also let you graph how decreasing pH (i.e. increasing acid) affect shell weight.

If you put containers in the refrigerator and compare them to those at room temperature, you are introducing a second variable, but if that is something your are interested in, you can test two things in your one experiment as long as you make sure to use all of your controls. You will need to have regular and acidified water at both temperatures. That way you can determine both the affect of pH and the affect of temperature.

I don't see any reason why you can't use pH paper instead of a pH meter. pH paper will be less accurate and less sensitive than a pH meter, but should be sufficient for your purposes. To help control for accuracy, consider measuring each pH multiple times (multiple strips of paper) and then using an average of your readings.

I hope this helps, and if you have any more questions, don't hesitate to post again in this forum.
JMP

[oceanman1]

Hi JMP,

Thanks for your help. I set the experiment up.

Oceanman1

[deleted-71536]

Hi Oceanman1,

JMP has already given you some great advice, and I'm glad to hear that you have set up your experiment.

One thing I want you to note is that you need to dry your shells when you weigh them. Sometimes the shells take on water during the soaking process, and they can appear to increase in weight if you weigh them wet. Drying the shells on paper towels should do the trick, and it is okay to plop them back into the solution once you have weighed them dry. (Like JMP said, the important thing is to keep the procedure the same for all of your treatments.)

Good luck, and please post again (in this same thread) if you have any questions along the way.

Heather