Particle-laden Eurasian Arctic sea ice: observations from July and August 1987

Abstract

During the summer 1987 expedition of the polar research vessel‘Polarstern’in the Eurasian Basin of the Arctic Ocean, sea ice at about 84‐86°N and 20‐30°E was found to have high concentrations of particulate material. The particle‐laden ice occurred in patches which often darkened more than half the ice surface at our northernmost positions. Much of this ice appeared to be within the Siberian Branch of the Transpolar Drift stream, which transports deformed, multi‐year ice from the Siberian shelves westward across the Eurasian Basin. Lithogenic sediment, which is the major component of the particulate material, may have been incorporated during ice formation on the shallow Siberian seas. Diatoms collected from the particle‐rich ice surfaces support this conclusion, as assemblages were dominated by a marine benthic species similar to that reported from sea ice off the coast of northeast Siberia. Based on drift trajectories of buoys deployed on the ice it appears that much of the particle‐laden ice exited the Arctic Ocean through the Fram Strait and joined the East Greenland Current. Very different sea ice characteristics were found east of the Yermak Plateau and north of Svalbard and Frans Josef Land up to about 83‐84°N. Here sea ice was thinner, less deformed, with lower amounts of lithogenic sediment and diatoms. The diatom assemblage was dominated by planktonic freshwater species. Trajectories of buoys deployed on sea ice in this region indicated a tendency for southward transport to the Yermak Plateau or into the Barents Sea.

Holocene climate variations at the entrance to a warm Arctic fjord: evidence from Kongsfjorden trough, Svalbard

“…This is inferred from a study in proximity to our core site that shows IRD larger than 500 mm in the eastern Fram Strait primarily originates from icebergs and not sea ice in this area (Hebbeln 2000). Moreover, sea-ice sediments are often fine grained although in some cases they exhibit grainsize distributions similar to icebergs (Dowdeswell 1989;Pfirman et al 1989;Gilbert 1990;Wollenburg 1991;Nürnberg et al 1994;Dowdeswell et al 1998). Different types of glacial activity, including active ice-streams (Dowdeswell et al 1994), glacial retreats (Powell 1984;Dowdeswell et al 1998;Vorren & Plassen 2002) or glacial advances (Dowdeswell et al 1998;Vorren & Plassen 2002) generate icebergs.…”

Arctic ice export events and their potential impact on global climate during the late Pleistocene

“…During the last 10 kyr the weight percentages of the >63 μm fraction are <4% (Figures 2 and 5), suggesting transport by sea ice rather than iceberg rafting [ Pfirman et al , 1989; Reimnitz et al , 1998; Nürnberg et al , 1994]. The increase in Fe oxide grains from unglaciated Russian shelves such as the Laptev Sea supports sea ice rafting as the most important transport process during the Holocene.…”

A contribution to the discussion of biota dispersal with drift ice and driftwood in the North Atlantic

“…(1987) proposed that an average of 20% of the total ice volume in the Fram Strait contained debris and estimated the annual sediment flux in the Fram Strait to 15 × 10 7 tons. Particulate matter may reach 560 g kg −1 ice in the Siberian branch of the Transpolar Drift Stream (Pfirman et al ., 1989). Most debris consists of sea floor sediments entrained in ice formed in open, turbulent, supercooled water in the shelf areas (Kempema et al ., 1989; Reimnitz et al ., 1993; Nürnberg et al ., 1994; Pfirman et al ., 1995a).…”

“…Koc et al ., 1993; Koc & Jansen, 1994; Sarnthein et al ., 1995) and ice drift patterns in the Arctic and sources and entrainment processes of ice‐rafted debris (e.g. Larssen et al ., 1987; Pfirman et al .,1989, 1990, 1995a,b, 1997a,b; Rigor, 1992; Nürnberg et al ., 1994; Reimnitz et al ., 1994; Proshutinsky & Johnson, 1997) as well as dendrochronological identification of sources and potential transport routes of driftwood (Fig. 1) (Bartholin & Hjort, 1987; Eggertsson, 1993, 1994a,b; Johansen, 1998, 1999) offer an opportunity to review some disjunct phytogeographical distribution patterns in the North Atlantic region.…”