This study of the marine chemistry of the Weddell Sea during the austral winter 1989 will extend a series of studies of the biological productivity of the Weddell Sea to wintertime conditions. The principal investigators will be part of an international team on board the West German R/V POLARSTERN which will make a northwest-southeast transect across the Weddell Gyre to complement earlier winter cruises in the eastern and central Weddell Seas in 1981 and 1986. The study will emphasize the distribution of dissolved oxygen, nutrients, and biogenic particulates (Silicon, Cargon, Nitrogen) to examine the processes which lead to the typical profiles of moderate concentrations in the surface layers, increasing to high, occasionally maximum, values near 1000 meters, and remaining at uniformly high concentrations in the deep water. Ancillary hydrographic observations will allow a possible quantification of wintertime mixing processes which renew nutrients and deplete dissolved oxygen beneath the seasonal pack ice.