MICROPLASTICS

Every piece of plastic on the picture you see just underneath the text, I collected while I was walking on the beach. I started this habit a while ago: everytime I come across a piece of plastic, I pick it up and place it in the nearest bin. On this particular walk, I collected an astonishing number of 43 pieces over a 20 minute walk.

As you can see, these are not microplastics yet. But over time, they will start to desintegrate and break down into smaller pieces, also becoming microplastics.

If 20 minutes of walking and picking up whatever I come across concludes in this amount of plastics, you can imagine how much more plastic there is laying around, all over the beach and even... the world.

I decided to focus my thesis disseration on microplastic accumulation in seagrass habitats. Coincidentally, my supervisor during the Professional Practice will also be my promotor during the thesis. That's why we devoted a bit of time to explore the sampling methods for microplastic extraction in sediments of seagrass habitats. We did a small field campaign, where we wanted to test two different strategies to take sediment cores, to explore which is more practical in the field and at the same time also supplies enough sediment to give a signal with FTIR (Fourier-Transform Infrared) spectoscopy. This is a device that can detect and identify plastic particles.

MICROPLASTIC SAMPLING

My supervisor, an IMBRSea colleague Lorena and I set out to the Ria Formosa for this fieldwork when the springtide was at its lowest. We wanted to test two different strategies to take sediment cores for subsequent microplastics extraction. For the first strategy, three cores (identified as MP1, MP2, MP3) with diameter 4,6 cm and length 50 cm were buried in the sediment in a triangular setup. Later, sediment from all three cores will be pooled to obtain enough material. The pooled samples will consist of slices from the same corrected depth at 2 cm intervals. In the second strategy, only one core (identified as MP4) with diameter 8,5 cm and length 20 cm was used to obtain sediment. Here, also slices of 2 cm intervals will be used for analysis.

Cores MP1, MP2 and MP3 were manually inserted into the soil, after clearing the seagrass strands, and pulled out of the sediment using a rope attached to the PVC tube by clasps, as you can see in the pictures of the left and in the middle . Core MP4 was manually inserted in the soil, but instead of being pulled out with clasps, it was dug out, as seen in the right picture. This was possible because this core was quite short. For my thesis, we want to get a look into the temporal scale of microplastics accumulation over a 70 year period, because that's around the time where plastic was being produced on a global scale. For this, we will need cores of around 1 m length, to be sure we get the sediment from the right time of deposition. Having to dig out a core this long may may pose more challenges in this case...

The plan was to start working on the analysis of all four cores, to see which strategy would give the better signal and is the most practical. Unfortuneately, there wasn't enough time to complete all of it, so the results aren't in yet. If you want to know the rest of this story, you will have to have a look into my thesis dissertation next year! In any case, we had a lot of during the fieldwork.