Author: Robert Bair
It has been a very long and laborious week. Bright and early Monday morning I started the first portion of the absorption experiment. I set up 27 bottles containing either tap water (as a control) or a highly diluted solution of zinc and duckweed. Measuring out an exact amount of duckweed was quite a challenge. It was during this part of the experiment that I learned a very valuable lesson; duckweed sticks to everything. It sticks to glassware, stirring rods, pipettes, fingers, and my lab notebook. It also likes to sneak into places it shouldn't go. I found a piece of duckweed stuck to my backpack, which I had left outside of the lab. I still don't know how it got there.
Once in the bottles, the duckweed was left to absorb the metals for 30 hours. After the 30 hours I started on the “desorption” part of the experiment. This part of the experiment is done to see how much of the metal is simply absorbed (a process which is reversible by simple pH change) and how much is actually uptaken by the plant (not reversible). It was during this part of the experiment that I wished I had eight or more arms. I had to take the plants from each bottle and place them into three different solutions: EDTA, CaCl2 and HCl. For each different solution I needed to put them in for three different times. I found myself at a loss for limbs… Octopuses would make excellent research assistants…
Once the desorption experiment was concluded I had to desiccate the plant samples. While these where in the oven, I was free to start the metal sampling. It was the first time I really used the AAS flame and the TOC. The AAS flame is a really fun piece of equipment to use. It doesn’t have an auto sampler, so you have to manually insert each sample. I enjoyed watching the flame change hues with each new sample.
The experiment isn’t over with. I still have to plot my results and I still need to digest my plant samples in a microwave (I wish this piece of equipment had a more interesting name). I have run out of “influent” to refresh my plants. I will have to go to a wastewater treatment plant with a bucket sometime later this week. I’ll have more info on this as time goes on.
The experiments usually take all day long. I haven’t had too much time to do anything else. I have started making myself a tent. As you might be able to tell by now, I spend most of my spare time building things. I’ll have pics of the tent once I am done.