Differentiating fluvial components of upper Canada Basin waters on the basis of measurements of dissolved barium combined with other physical and chemical tracers

The utility of dissolved barium (Ba) as a quasi‐conservative tracer of Arctic water masses has been demonstrated previously. Here we report distributions of salinity, temperature, and Ba in the upper 200 m of the Canada Basin and adjacent areas observed during cruises conducted in 2003–2004 as part of the Joint Western Arctic Climate Study and Beaufort Gyre Exploration Project. A salinity–oxygen isotope mass balance is used to calculate the relative contributions from sea ice melt, meteoric, and saline end‐members, and Ba measurements are incorporated to resolve the meteoric fraction into separate contributions from North American and Eurasian sources of runoff. Large fractions of Eurasian runoff (as high as 15.5%) were observed in the surface layer throughout the Canada Basin, but significant amounts of North American runoff in the surface layer were only observed at the southernmost station occupied in the Canada Basin in 2004, nearest to the mouth of the Mackenzie River. Smaller contributions from both Eurasian and North American runoff were evident in the summer and winter Pacific‐derived water masses that comprise the underlying upper halocline layer in the Canada Basin. Significant amounts of Eurasian and North American runoff were observed throughout the water column at a station occupied in Amundsen Gulf in 2004. This suggests the export of runoff from both sources through the passages of the Canadian Arctic Archipelago.