Cadmium and barium distributions in Baffin Bay and Nares Strait summer 2003

Baffin Bay serves as the conduit of relatively fresh Arctic waters to the deep convection region of the Labrador Sea. As part of an effort to develop proxies for presence and possibly flux of freshwater through the region in the past, multiple oceanographic tracers were profiled in the water during the July-August 2003 Healy cruise to Baffin Bay and Nares Strait. Here we report results for isotope-dilution inductively coupled plasma mass spectrometry analyses of those samples for both cadmium and barium. Samples for Ba were diluted 20-fold and Cd samples were separated from sea salts via resin exchange. Both of these elements are enriched in Bering winter water and, compared to lower latitude open ocean settings, relatively enriched in Arctic surface waters that are influenced by both fluvial inputs and the sea-ice cover. Such enrichments are reflected in profiles of both elements in Nares Strait. Surface enrichments are reduced downstream in Baffin Bay where ice-free conditions reliably persist for at least part of the year. The removal of Ba in association with biological activity in passages of the Canadian Archipelago and Baffin Bay obviates its use as a tracer of fluvial inputs in those settings. Both Cd and Ba concentrations increase with depth in Baffin Bay reaching values of 0.5-0.6 nM and 108 nM respectively in the more isolated bottom waters. Their profiles likely reflect the different water types contributing to Baffin Bay coupled with substantial regeneration at depth. Cadmium to phosphate ratios (Cd:P) deviate by up to nearly 300% from usual open ocean trends with a Cd enrichment with respect to P for all but the deepest samples.