1994 Arctic Ocean Section
What Can Be Learned from Barium Distributions
in the Arctic Ocean?
Kelly Kenison Falkner
Barium is one of several naturally occurring inorganic elements that are
being studied as part of a larger project to track river- and shelf-modified
water inputs to the central Arctic. In the open oceans, dissolved barium displays
nutrient-type behavior, being depleted from surface waters in conjunction
with biological processes and enriched at depth by regeneration. River waters
tend to be enriched in dissolved barium with respect to surface seawaters, and
riverine signals are further augmented in estuaries where barium adsorbed on
riverine clays is desorbed as the clays encounter the more abundant cations of
seawater.
AOS-94 samples have been analyzed for dissolved barium content by isotope
dilution-inductively coupled plasma quadrupole mass spectrometry. Several
interesting observations can be made when these results are taken in the con-
text of previously reported barium data for the Arctic (Falkner et al. 1994) and
recent results from 19931995 field efforts, including extensive sampling along
the Russian and Siberian estuarine and shelf regions, in the Mackenzie Delta
as well as the 1993 USS Pargo and 1995 Cavalla nuclear submarine missions
(Falkner and Guay, unpublished data). All of these data sets have been cali-
brated to a common barium standard and have a precision of 3% or better.
Consistent with its higher suspended sediment loads, the Mackenzie River
appears markedly enriched in barium compared to the rivers of the eastern
Arctic sector. Sub-ice surface (< 25 m) barium concentrations in the central
Arctic range from 35 to 70 nM and show a spatial distribution reflecting both
the varying riverine inputs and the integrated surface ice motion. The highest
values are concentrated in the Beaufort Gyre region, which is influenced by
Mackenzie inputs. Intermediate values influenced by the Siberian rivers track
the transpolar drift and are bordered toward the Fram Strait and Barents Shelf
by low values characteristic of North Atlantic surface waters.
As previously observed, halocline waters that display elevated silicon con-
tents and are believed to originate from the BeringChukchi regions also show
pronounced barium maxima (up to 140 nM). At stations where halocline
Kelly Kenison Falkner is from the College of Oceanic and Atmospheric Sciences of Oregon State
University, Corvallis, Oregon, U.S.A.
32
Previous Page
