Abstract:
Dissolved barium (Ba) was measured along transects across Fram and Denmark
Straits as part of the 1998 ARK-XIV/2 Polarstern expedition. Results are combined
with other available tracer observations to analyze water mass composition at Fram Strait. A
combination of Pacific water and Eurasian river runoff dominated (>80% and >10% of the
total mass, respectively) the upper East Greenland Current (EGC), while the remainder of
the section was dominated by North Atlantic water. A much smaller contribution of
Pacific water to the EGC (≈50%) at Fram Strait in 1987 suggests that this component can be
quite variable in time. North American river water was not detectable at Fram Strait in 1998.
Presumably, the Eurasian river water we observed at Fram Strait transited eastward along
shelf within the Arctic, mixed with Pacific water in the vicinity of the East Siberian Sea,
and was borne by the transpolar drift across the Arctic Ocean. In the absence of
significant net ice formation along the way such a pathway can be expected to produce more
pronounced freshening of the EGC than when Eurasian river water mixes more directly off
shelf into salty Atlantic waters and Pacific water is diverted largely through the
Canadian archipelago. Existing measurements at the main Arctic gateways were used to
construct a Ba budget for the Arctic Ocean under conditions of simultaneous mass, heat,
and salt conservation. This preliminary budget is statistically consistent with the steady state
hypothesis. On the Arctic basin scale, Ba appears to be conservative.
