DISSOLVED GALLIUM IN THE ATLANTIC-OCEAN

Gallium is geochemically similar to aluminum, though less reactive. As such, gallium is potentially useful to resolve questions about the al uminum distribution. Dissolved gallium data from 14 profiles in the At lantic Ocean as well as additional surface water samples are presented here. The results verify that the main delivery of gallium to the sur face ocean is aeolian and that gallium has a surface water residence t ime longer than aluminum but probably similar to manganese (i.e., orde r of decades). Surface water gallium concentrations in the Sargasso Se a are unusually high (>40 pmol kg(-1)). There is likely an anthropogen ic component in the Sargasso Sea, but residence time effects may also be at work. Dissolved gallium profiles in the Atlantic are generally s imilar to those of aluminum. The subsurface gallium maximum previously observed in the northeast Pacific is not found, but may be obscured b y advective features in the Atlantic. Deep waters in the Atlantic show generally conservative behavior of gallium, supporting the concept of using aluminum as a deep water tracer in the Atlantic. However, galli um enrichments are observed in the deep waters of the Norwegian Sea an d Iceland Basin. A consideration of possible sources of these enrichme nts suggests that release from resuspended sediments is the most likel y source mechanism. (C) 1998 Elsevier Science B.V.