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 Rin ges Island in 1989-1990 provided year-round measurements of particulat e matter sedimentation in a permanently ice covered region of the Arct ic 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 s ediment traps from the Canadian Ice Island at a water depth of 100 m. High flues of mass, biogenic silicon and inorganic matter occurred bet ween July and September during the melt-water runoff. Maximum sediment ation of organic matter and chlorophyll a occurred in August and Septe mber when centric diatoms and zooplankton fecal pellets were numerous in samples. Between February and June, when mass flues were low, settl ed particles were organically rich with low carbon:nitrogen ratios (4- 8) in contrast to higher values (6-12) during the melt-water period. M ineralogy showed that chlorite, mica, illite and quartz were abundant in settled particles collected in August, October and December. Simila r minerals, thought to be supplied as small particles by eolian transp ort, are present in ice cores and cryoconites on the Ice Island. The o bservations provide data for assessing future changes in production an d 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 .