Strong offshore winds in early 1989 produced a shore polynya that reac
hed along the entire north coast of Alaska and eastward beyond the mou
th of the Mackenzie River in Canada. From January through April, this
open water periodically exposed the shelf to sediment entrainment by s
uspension freezing. This process requires turbulence and supercooled w
ater, which results in the formation of frazil and anchor ice. The res
ulting granular, sediment-laden ice was observed to extend over 100 km
seaward of the outer continental shelf after having been advected off
shore. It was sampled to determine sediment type and to quantify the p
article load. The particle size was mainly silt and clay, with local a
dmixtures of as much as 27% sand and coarser clasts. Melted ice sample
s contained from 31 to nearly 600 mg L-1 of sediment. Combining these
data with over 400 km of shipboard and aerial observations, photograph
s, and computer analysis of a summer Landsat image, we estimated the s
ediment load per unit area of sea ice. Seaward of the shelf, in region
s of dense pack ice, a conservatively estimated sediment load was over
289 t km-2. Using a westward summer drift rate of 3 cm s-1, the sedim
ent transport through a 1-km-long north-south segment is 67,418 t duri
ng 3 mo. In terms of regional sediment dynamics (littoral transport es
timated at 10,000 t during the same period) and sediment budget (conti
nental denudation estimated at 10 t k-m2 during the same period), this
number is very significant. Benthic microfossils indicate that bottom
sediment incorporated in the ice came from water depths ranging from
the inner neritic seaward to 50 m. The large load of shelf-derived sed
iment observed seaward of the continental shelf indicates that ice ent
rainment and transport cause shelf erosion. Nothing is known about sed
iment release over the Arctic Ocean Basin from these pulses of dirty i
ce that are periodically introduced into the Transpolar Drift.