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Two sampling expeditions to the coastal and offshore Beaufort Sea to study the sediment in the ice of the Beaufort Gyre encountered high sediment concentrations. Sediment concentrations in the sea-ice obtained during the Spring expedition averaged 49.5 mg/L, but ranged up to 821 mg/L. Concentrations measured during an offshore icebreaker cruise in August and September averaged 364 mg/L and ranged up to 10002.7 mg/L in part of a subsampled core. This average concentration is an order of magnitude greater than measured during similar field efforts in 1992. Spring studies indicated that sediment was prevalent in ice offshore of the stamukhi zone while ice inshore was relatively sediment-free. Studies at the end of summer found significant concentrations found as far as 79.5°N in the relatively sparse ice pack. Much of the sediment was found in pockets on the surface of first-year ice, although laterally discontinuous bands of sediment were seen within turbid ice in core sections suggesting entrainment by anchor ice. Most of the sediment consisted of clays and silts, although a 100km-wide belt of dirty ice off Point Barrow in the Fall included sands and gravels, as well as wood and leaves. Sediment was rare in samples from multi-year ice. Sediment concentrations in snow samples averaged 56.3 mg/L in the Spring and 2.4 mg/L in the Fall suggesting that aeolian processes are not major sediment contributors to offshore ice but may be an important local contributor to nearshore ice. Introduction As part of a continuing effort to discern climate change in geologic history, and to understand the relationship between climate change, and the Arctic Ocean ice pack, the U.S. Geological Survey undertook two expeditions to the Beaufort Gyre in 1993 (Figure 1). The first sampled ice in April and May and was incidental to a study of methane gas concentrations in Beaufort shelf water and ice (Kvenvolden et al., in press) (Figure 2). The second used the US Coast Guard Cutter Polar Star as a base for ice sampling during the fall of 1993 (Figure 3). Operations included geophysical transects, piston and box coring, water mass sampling and analyses, and the investigation of physical characteristics of the ice pack. This report presents data concerning the last of these emphases. Preliminary reports on other research can be found in Grantz et al. (1993). Our study of the pack ice centered on three major research thrusts; First, the quantity and type of sediment contained in the Arctic ice pack and its method of entrainment. Second, the post-entrainment fate of the sediment in the Beaufort Gyre circulation patterns (Figure 1), and the metamorphosis of the ice/sediment mixture with age. Thirdly, the effect of the sediment on visible wavelength spectral signals and the ice albedo. The first two questions have been addressed recently by Barnes et al. (1982), Osterkamp and Gosink, (1984), Kempema et al. (1986; 1989; 1993), McCormick et al. (1993), Reimnitz et al. (1987; 1990; 1992; 1993a; 1993b; 1993c ), Reimnitz and Kempema, (1987), and Clayton et al. (1990) primarily from studies of coastal areas. The effect of sediment on the albedo will be the subject of future publications. Studies on the Beaufort Sea shelf indicate the inshore region (0-30 m; ranging down to 50 m) as the source for ice rafted sediment in the deep basin (Reimnitz et al. 1992; 1993a,c). However, only two major sediment entrainment events producing turbid ice occurred during 20 years of study (Kempema et al., 1989; Reimnitz et al., 1993c). The sediment load carried by the pack over the Canada Basin is highly variable (Reimnitz et al., 1993a, 1993c). The 1992 Polar Star cruise (McCormick et al., 1993) found little turbid ice. Considering the observed variability and the small portion of the polar ice pack that has been sampled, our knowledge is insufficient to permit generalizations about sea-ice sediment transport during interglacial times. This year's cruises were aimed at broadening that data base, determining the

Studies of sediment transported by Beaufort Gyre pack ice, Arctic Ocean, 1993; concentrations, textural and carbon data