Assessing the Impacts that the Atlantic Ocean’s changing Physical Properties will have on Suspended Cohesive Fine-grained Particle Transport to the Arctic.

Abstract:

The Arctic Ocean and its sea-ice play a central role in transporting cohesive fine-grained particles around high-latitude regions. The rapid melting of this Arctic sea-ice is changing the salinity, temperature and density characteristics of the North Atlantic Ocean, as well as affecting particle transport, accumulation and distribution within the Arctic. These changes then have potential knock-on effects for larger-scale oceanic processes like the Atlantic Meridional Overturning Circulation (AMOC). Changes in the density structure and the current strength of the Atlantic Ocean both have consequences in how suspended fine-grained cohesive particles are transported through it. When these predominantly cohesive particles flocculate and form flocs, microplastics, pollutants/contaminants etc. are often captured and transported within their low density, porous, compositional matrix. By utilising 21-year datasets from 1^st January 1998 to 31^st December 2018 for Arctic sea-ice and for Atlantic Ocean salinity, temperature and density, as well as a dataset running from 1^st April 2004 until 2^nd September 2018 measuring AMOC layer transports at 26.5ºN, the likely implications for these floc structures and their transport can be theorised. The physical properties of the Atlantic Ocean have gradually altered and evolved, becoming more or less dependant on location as well as the depth of the water column. Some areas around both the Western and Eastern coasts of Greenland see reductions in surface density as high as 2 kg/m³ over the study-period, although changes at deeper depths are less evident. This means different consequences for floc structures and their transport, and these are dependent on where and when they enter the Atlantic Ocean. A number of environmental scenarios will be examined and assessed.