SEASONAL VARIABILITY IN PARTICLE SEDIMENTATION UNDER PERMANENT ICE COVER IN THE ARCTIC-OCEAN

A study at 79 degrees N over the polar continental shelf off Ellef Ringes Island in 1989-1990 provided year-round measurements of particulate matter sedimentation in a permanently ice covered region of the Arctic Ocean. Mean annual Aux rates of mass (1.1 g m(-2)), organic carbon (134 mg m(-2)), nitrogen (24 mg m(-2)), chlorophyll a (3 mg m(-2)) and biogenic silicon (II mg m(-2)) were determined by deployment of two sediment traps from the Canadian Ice Island at a water depth of 100 m. High flues of mass, biogenic silicon and inorganic matter occurred between July and September during the melt-water runoff. Maximum sedimentation of organic matter and chlorophyll a occurred in August and September when centric diatoms and zooplankton fecal pellets were numerous in samples. Between February and June, when mass flues were low, settled particles were organically rich with low carbon:nitrogen ratios (4-8) in contrast to higher values (6-12) during the melt-water period. Mineralogy showed that chlorite, mica, illite and quartz were abundant in settled particles collected in August, October and December. Similar minerals, thought to be supplied as small particles by eolian transport, are present in ice cores and cryoconites on the Ice Island. The observations provide data for assessing future changes in production and particle export for this ice-covered region of the Arctic Ocean that may be altered due to global warming and related changes in ice cover.