Microplastics and organic contaminants

Olivier Smith

 

In collaboration with :

Vincent Fauvelle - Mediterranean Institute of Oceanology (MIO)

Emilie Strady - MIO

Microplastic (0.3-1mm) and nanoplastic (<0.1mm) particle pollution is a global problem that affects all oceans. Plastic particles have been spotted trapped in Arctic ( Peeken et al. 2018 ) and Antarctic ( Kelly et al. 2020 ) sea ice.

The effects of these plastic particles are multiple: in addition to their accumulation in the digestive systems of marine fauna, these particles transport organic additives ( Campanale et al. 2020 ) and microorganisms ( Dussud et al. 2018 ) to the various marine ecosystems of the globe.

Atlantic and Southern Oceans: What is the current state of

microplastic pollution in these places?

Does it also reach the Antarctic continent?

 

In practice:

The study is divided into 4 thematic sections:

 

  • Seawater: The boat trip is an opportunity to use the equipment available to study surface microplastics in the Atlantic Ocean. Regular collection is carried out there, using a "manta" type microplastic net.  The samples thus collected are analyzed using an LDIR system, combining microscopy and infrared spectroscopy .

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Microplastic net on deck

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A sieve is used to filter the water contained in the net collector

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The sieve is rinsed and the washing water is collected: it contains plankton and... microplastics!

Sediments: Once on the Antarctic continent, it becomes possible to study other environments affected by plastic pollution, in particular sediments and snow. 5 one-litre replicates of coastal sediments are collected from the penguin colonies selected by Lana for her study . Each sample is mixed with one liter of water saturated with salt (NaCl) to allow separation by density of the materials. Microplastics, which are less dense, will mostly float to the surface. This surface layer is then collected and stored to be analyzed in LDIR.

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Fresh snow: Snow tends to incorporate particles suspended in the air. So when we observe microplastics in fresh snow, we confirm the presence of microplastics in the air at this location. Here, snow collection is an opportunity to complement the sampling points of Bergmann et al. 2019   who found the presence of microplastic in Arctic and Alpine snow. We will be able to highlight or not the presence of atmospheric microplastics in a region as remote as Antarctica. Again, the analysis is done by LDIR.

 

 

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Right: filtration of melted snow. The system is covered with a protective film to prevent dust from settling in the filtered water.

Organic contaminants: these are polluting molecules that are sometimes added to plastic or other materials to change their properties (additives). These molecules are therefore present in microplastics, and by transport can thus disturb an ecosystem that is far from pollution areas. Studying these molecules can be quite difficult, because there is a great diversity of them (we are interested in about 70 different compounds) and they are very dilute in seawater, barely detectable.

To collect these molecules from the environment, gel cartridges containing a polymer are used to absorb a wide variety of molecules. Each cartridge is left for 48 hours to infuse in 1L of collected seawater, then stored cold. On returning to France, analyzes by mass spectroscopy (LC-MS and GC-MS) make it possible to know the diversity and quantity of these molecules in the water.

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The gel cartridge left to soak in seawater for 48 hours. The bottle is made of glass to avoid any traces of plastic or additives in the sample.

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Addition to the sample of a known quantity of a pollutant (here BisphenolA) marked with deuterium, therefore not present in the environment.

The laboratory measurement should make it possible to find exactly this concentration of deuterated Bisphenol A to validate the result.