In the nutrient-rich Southern Ocean, Fe is a vital constituent controlling the growth of phytoplankton. Despite much effort, the origin and transport of Fe to the oceans are not well understood. In this study we address the issue with geochemical data and Nd isotopic compositions of suspended particle samples collected from 1997 to 1999 in the South Atlantic Sector of the Southern Ocean. Al, Th, and rare earth element (REE) concentrations as well as 143Nd/144Nd isotopic ratios in acetic acid-leached particle samples representing the lithogenic fraction delineate three major sources: (1) Patagonia and the Antarctic Peninsula provide material with eNd > -4 that is transported toward the east with the polar and subpolar front jets, (2) the south African shelf, although its influence is limited by the circumpolar circulation and wind direction, can account for material with eNd of -12 to -14 adjacent to South Africa, and (3) East Antarctica provides material with eNd of -10 to -15 to the eastern Weddell Sea and adjacent Antarctic Circumpolar Current. For this region we interpret the Nd isotopic evidence in combination with oceanographic/atmospheric constraints as evidence for supply of significant amounts of terrigenous detritus by icebergs.

Samples collected under way from surface water with a cont. centrifuge on Polarstern on 3 expeditions: ANT-XV/2, ANT-XV/3, ANT-XVI/3. 143Nd/144Nd ratios were normalized to 146Nd/144Nd = 0.7219 and correspond to 0.511850 in La Jolla Nd standard.

Supplement to: Hegner, Ernst; Dauelsberg, Hans-Jürgen; Rutgers van der Loeff, Michiel M; Jeandel, Catherine; de Baar, Hein J W (2007): Nd isotopes constrain the origin of suspended particles in the Atlantic sector of the Southern Ocean. Geochemistry, Geophysics, Geosystems, 8, Q10008