On the origin of the properties of the Arctic Ocean halocline north of Ellesmere Island: results from the Canadian Ice Island

Abstract

Profiles of several chemical constituents measured in 1985 and 1986 from the Canadian Ice Island above the continental shelf north of Ellesmere Island are similar to those obtained at more central regions of the Arctic Ocean. Three types of water characteristic of the Canada Basin of the Arctic Ocean can be identified: surface water containing river runoff from Siberian rivers, halocline water formed on the Eurasian continental shelves of the Arctic Ocean, and deeper water of Atlantic origin. The profiles suggest that the water at the Canadian Ice Island may be older than that further to the north. Incubation experiments conducted at near-freezing temperatures with sediments collected from under the Canadian Ice Island showed the release of nutrients at in situ temperatures to be much lower than for the Asian and European continental shelves of the Arctic Ocean. At higher incubation temperatures, the release rates increased to values comparable with those found on other continental shelves. This implies that nutrient concentrations in the water column at the Canadian Ice Island are not locally regenerated to a significant degree in spite of there being an adequate supply of biogenic matter in the sediments.