Animal, Vegetable, Mineral?

This week I got back into extracting microplastics from sediment samples that I collected in October. After some reading, calculations, and failed attempts, I finally got the chemical solution I needed. You see, microplastics are often more dense than seawater, which is why they may sink or float partially submerged in the water column. When I extract nematodes, I can use a solution with a density of 1.18 g/mL, as they are not extremely dense organisms. However, some plastics have densities closer to 1.7 g/mL, and so a solution like the one pictured here must be made. The thermometer-looking tool sticking out of the solution is a hydrometer, which measures the density of liquids. When placed in a liquid, the hydrometer will float or sink and stop at the level of neutral buoyancy, where you can read the density of the liquid.

Today I was able to make enough of this solution to process 4 more samples and still have enough for another few days at the lab. The challenge in microplastics extractions, however, is not necessarily in making chemicals or processing samples. The biggest challenge in my opinion is analyzing the data. Below you can see a picture of a portion of one sample that I processed today. In the lower third of the picture there is something that appears to be a fiber. However, there are many items it could be; part of a plant, a very pointed nematode; another small animal; cellulose which is a natural fiber. Therefore, finding fibers like these doesn't tell me much until I do the final step which is to run these through a machine to determine what the items are made of. Only then can I be certain about what is plastic, so the journey has just begun. Right now, I think I will start referring to potential microplastics as animals, vegetables, or minerals like the old game show, because it's anyone's guess at this point.

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