Scientific program
2020 expedition
Phase 1: Sampling
Part of our work involves taking seawater samples to collect microplastics. Depending on the partners and their needs, the nets used and the protocols followed are not the same.
In the water column
The protocol for sampling in the water column has been validated by the 2017, 2018 and 2019 expeditions. It uses a closing net which can be dove up to 150 m deep. It is then trawled back to the surface. A mechanism allows us to close the net at any depth. Expedition 2020 uses this protocol to sample micro-plastic between 30 m and 80 m depth. The micro-plastics recovered measure between 100 μm and 5 mm.
On the surface
The manta net allows sampling on the surface of the water, in the first 15 cm of the water column. Throughout the sampling period, the net must be towed by the moving boat at a speed of between 3 and 5 knots.
In 2022, the crew embarked 2 different manta nets. One has a mesh of 125 µm (LNE - AgroParisTech) and the other* of 300 µm (Oceaneye).
*This net was lent to us by the Swiss Cetacean Society
Sampling of nanoplastics
In Depth: Niskin Bottles
Sampling of nanoplastics is done using four Niskin bottles . These are sampling bottles, used to take water from a given depth, by lowering them at the end of a cable into the sea.
For SEA Plastics, in 2021, four Niskin bottles were immersed in the water column, then brought back on board, where the samples passed through sieves of increasingly fine mesh, to then be filtered on a microfiber support of glass that will keep all particles between 700 nm and 50 µm.
Glass microfiber media in 2021 made sample analysis difficult. In 2022, tests will perhaps be carried out with a support of a different nature.
.jpg)