Carbon biogeochemistry of the western arctic: Primary production, carbon export and the controls on ocean acidifi cation

The Arctic Ocean is an important sink for atmospheric carbon dioxide (CO₂) with a recent estimate suggesting that the region accounts for as much as 15 % of the global uptake of CO₂. The western Arctic Ocean, in particular is a strong ocean sink for CO₂, especially in the Chukchi Sea during the open water season when rates of primary production can reach as high as 150 g C m -2. The Arctic marine carbon cycle, the exchange of CO₂between the ocean and atmosphere, and the fate of carbon fi xed by marine phytoplankton appear particularly sensitive to environmental changes, including sea ice loss, warming temperatures, changes in the timing and location of primary production, changes in ocean circulation and freshwater inputs, and even the impacts of ocean acidifi cation. In the near term, further sea ice loss and other environmental changes are expected to cause a limited net increase in primary production in Arctic surface waters. However, recent studies suggest that these enhanced rates of primary production could be short lived or not occur at all, as warming surface waters and increases in freshwater runoff and sea ice melt enhance stratifi cation and limit mixing of nutrient-rich waters into the euphotic zone. Here, we provide a review of the current state of knowledge that exists about the rates of primary production in the western Arctic as well as the fate of organic carbon fi xed by primary produces and role that these processes play in ocean acidifi cation in the region.