Prepare for Lasers!

Side note before I talk about lasers: it seems as though the blog post from last week was posted without the text. Once I clicked on it today, all of the text showed up, so please feel free to read about last week's work too.

This week I was really excited to receive the final chemicals necessary for my work. Up until this point, I have extracted nematodes from sediment samples, extracted microplastics from sediment samples, and counted nematodes from the samples. However, I still need to learn more about the microplastics I have found, and to do so, I need lasers. The lasers in question will be the focus of a blog in two week's time (I get trained next week after the blog goes out). But why do I need chemicals if I'm working with lasers? Isn't that dangerous? Normally, I would be inclined to agree that mixing lasers and chemicals is probably not a smart idea. However, the extra step in my research serves an important purpose. Microplastics are often coated with other materials and those extra materials adhere to the plastics even when they are removed from their environment. Some items that are commonly attached to microplastics are bacteria, detritus (dead matter), natural elements/compounds, and sometimes additives that were added to plastics in the manufacturing process. Although I cannot see these items on the surface of the plastics using the microscope that I have, I recognize that the contaminants are likely there, and can make identifying the plastics challenging (again the focus of the blog in two weeks). Therefore, I need to run the particles through a chemical reaction.

The picture here shows two different reaction containers at two different stages in the chemical reaction known as the Fenton reaction. The reaction works by oxidizing the organic matter that may be attached to the plastics to create an iron oxide, then dissolving the iron oxide and treating the mixture with a detergent to ensure full removal of the materials. On the left is a reaction that is just beginning; the initial materials have been added to the container and the sediment/water mixture has taken on a very dark brown color. At the end of the ten minute reaction, the mixture looks like the reaction container on the right--lighter in color. After the ten minute reaction period has ended, the mixture is allowed to cool before adding the final chemicals which will dissolve the iron and clean the particles. The cooling step is really important because the chemicals that I use for this reaction are incredibly concentrated (for those of you curious it is 98% sulfuric acid and 30% peroxide), and any bubbling or splashing would be quite dangerous. Don't worry, I wear protective gear when working with these materials and stay within the safety of the fume hood the whole time.

Once the reaction has been run to completion, which takes 20 minutes, then I filter out the material so that I can capture any of the microplastics that were in the sample. Samples are now ready for analysis. Are there other ways to do this process? Yes, absolutely. However, in building out my research methods I have tried to use the methods that were most supported by research at the time, and a paper within the past 2 years found that the Fenton reaction was better than other options.

So what's next, you may ask. By Saturday of this week, I should be done with the Fenton reaction for 135 of my samples and I can start analyzing them--hence the training next week. To prepare for analysis, I will be looking at all of the samples under the microscope and counting potential microparticles, since I will not need to analyze samples that don't have microplastics. I also will be taking photographs of the particles to collect size, color, and particle type (fiber, fragment, film, etc.) data. Finally, I will be returning to nematode counting, since I hope I can finish all the fall and winter nematode samples for a research seminar i am giving at the end of this month. It's a big task, but I want to push myself because I feel like I have not had data for such a long time.

Finally, this week I also had the amazing opportunity to participate in an early career researcher international microplastics workshop, where I was able to talk with experts in the field, from around the globe, about different microplastics methodologies, their research, and future directions. It was such a great opportunity, especially since I got time to talk with two researchers whose works have guided some of my own experimentation.

Stay tuned for next week's blog that just might have some great microplastic pictures for you.

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