Numerical models and Plastic Pollution report 16 September 2019

This is the end of summer and we try to prepare for the winter flow of plastic. We had only a very short period of low plastic pollution rate (c. 1kg/day) restricted to august and overall we recovered much more plastic than we used to this summer. However winds were not really strong and the sea stayed relatively cold and calm.

We are actively working to better understand what is going on and why do we receive so much pollution in Balnakeil Bay. There has been many papers recently explaining that most of the pollution stock stays transient in the coastal areas and is not floating in the middle of the ocean immediately.

We have started an exciting collaboration with an environmental consultant, MTS-CFD, which creates numerical scenario to reproduce the observed pollution in our area. We have compared the predicted weights of plastics coming ashore from the models and from our 2.5 years of measures and it is strikingly similar and matches our regional observations.

simulation of 7 days of SW winds with 20 particles per sqkm (yellow circles). Colorscale shows the strength of the tidal currents.

For the first time we can see why some areas are covered in plastic and others are not. The tides suck the plastic from offshore and the wind pushes it on the SW-facing beaches. It is the first time we can sensibly explain the distribution of pollution in the area.