Problems of chemical constituents in seawater above the Alpha Ridge in the central Arctic Ocean obtained during the Canadian Expedition to Study the Alpha Ridge (CESAR) support a model in which the halocline is maintained by dense, saline water produced on the continental shelves within the Arctic Ocean by the formation of sea ice. It is argued that nutrient regeneration on the continental shelves largely accounts for the nutrient maximum that has been observed in the upper halocline over a wide region of the Arctic Ocean, and that while the Bering Sea and North Atlantic can be recognized as origins of halocline water, water masses from these regions undergo sufficient changes in their chemical properties within the Arctic Ocean significant that they no longer retain their identity in the halocline.