Featured Science Paper
Tracer-derived freshwater composition of the Siberian Continental Shelf and slope following the extreme Arctic summer of 2007
We have been using geochemical tracer data to try to determine the freshwater content of Arctic Ocean waters. During a research cruise in 2007, we obtained water samples that were analyzed for dissolved barium, and the ratio between two isotopes of oxygen in seawater. These tracers are used together with salinity to determine the distribution of river water and sea-ice meltwater injected into the Arctic.
Combined with the chemical oceanography measurements undertaken by colleagues at NOCS, we can also use our water samples to determine how much of the water we measure in the Arctic was derived from the Atlantic and how much from the Pacific, of relevance since the Pacific water inflow is markedly fresher than the Atlantic inflow. Our results give indications of the pathways for the flow of freshwater from the Siberian continental shelves into the Arctic Ocean, something that we have seen to depend largely on variations in weather patterns over the summer.
The measurements of dissolved barium are traditionally used to trace the pathways of river water from the continental shelf into the Arctic basins, though our results from 2007 indicate that other factors (biological ones, specifically) can also influence the distribution of barium in regions of reduced sea-ice cover. This has potentially important implications for how barium is used as a tracer in the future, as sea ice in the Arctic continues to retreat rapidly.
Abrahamsen, E. P., M. P. Meredith, K. K. Falkner, S. Torres-Valdes, M. J. Leng, M. B. Alkire, S. Bacon, S. Laxon, I. Polyakov and V. Ivanov
Geophys. Res. Lett., 36 L07602, doi:0.1029/2009GL037341, 2009