Lagrangian pathways of 137Cs released from multiple sources in the Arctic Ocean

The Arctic Ocean and the North Pacific are the main reservoirs of anthropogenic radionuclides introduced in the past 80 years. The Lagrangian particle tracking approach was applied to the Arctic oceans to study the pathways of 137Cs contamination from point sources representing the locations of solid radioactive waste in the bays of the Novaya Zemlya archipelago and in the Kara Sea. The model includes radioactive decay and the interaction of dissolved radionuclides with suspended and bottom sediments. Lagrangian model uses accurate approach for simulating the absorption-desorption processes and novel algorithm for the bottom boundary conditions. As input for the model, the 3D hydrodynamic fields from NEMO model simulation with 10 km horizontal resolution and 121 vertical layers were used. 3D velocity fields along with vertical velocity and vertical turbulent mixing coefficient were used from NEMO simulation for 38 years from 1980 to 2018. Suspended sediment concentration fields were reconstructed using the 1D SEDTRANS05 sediment transport model in each grid node.

A set of potential scenarios of radioactive release were considered to analyse the most probable pathways of contamination. In each simulation, 1M of particles was used and individual trajectories were stored. The maps of visitation probability were built to show pathways of radioactivity contamination in the Arctic Ocean from the selected sources.