Deep water circulation and composition in the Arctic Ocean by dissolved barium, aluminium and silicate

As part of the ARK-XXII/2 Polarstern expedition in summer 2007, dissolved Ba was analyzed in the Eurasian Basins and the Makarov Basin including the Alpha and Mendeleyev Ridges as well as on the adjacent shelves. The data was compared with data of dissolved Al and Si from the same cruise. Superimposed on the gradual increase of concentration with depth by dissolution of the particle rain, we observe different flow patterns in intermediate waters along the track. In the Atlantic and Intermediate Depth Water (AIDW) in the Amundsen Basin the influence from Eurasian shelf water can be seen in slightly enhanced concentrations of dissolved Ba compared with Al and Si. At the same time Al concentrations decrease with distance from the Eurasian shelves. Source waters to the Atlantic Layer Water (ALW) in the Makarov Basin have the same background Ba concentrations as the Nansen AIDW. We describe the distributions of the elements in the Deep Eurasian and Bottom Water (DEBW) by deep shelf convection as well as diffusion from sediments controlling concentrations in the Nansen DEBW while in the Amundsen DEBW diffusion from sediments appears to be more important. In the Makarov Basin inflow from the Canadian Basin and overflow from the Amundsen Basin at 2000 m depth at the Lomonosov Ridge are required to explain the composition of bottom waters.