Biogenic Barium as a Proxy for Paleoproductivity: Methods and
Limitations of Application
F.X. Gingele*l, M. ZabeF, S. Kasten 2 , W.J. Bonn 3 and C.C. Niimberg 4
lInstitutfur Ostseeforschung, SeestraJ3e 15, D-18119 Rostock-Warnemunde, Germany
2Universittit Bremen, Fachbereich Geowissenschaften, Postfach 330440,
D-28334 Bremen, Germany
3 Alfred-Wegener-Institutfur Polar- und Meeresforschung, Postfach 12 0161,
D-27515 Bremerhaven, Germany
4Geomar, Marine Umweltgeologie, WischhofstraJ3e 1-3, D-24148 Kiel, Germany
*corresponding author (e-mail):Jranz.gingele@io-warnemuende.de
Abstract: The obvious link between sedimentary barium and past and present ocean productivity
has propagated numerous studies on this tracer in the past years. In this paper a summary is given
on what is known of the generation of the barium signal and its link to the flux of organic carbon. We
describe procedures to assess barium contents, distinguish biogenic from detrital barium and calculate
barium accumulation rates. Two approaches to estimate absolute paleoproductivity rates from barium
contents are described and compared. A considerable part of the paper is dedicated to synsedimentary
and early diagenetic constraints involved in the application of the barium method. It is demonstrated
that the most significant diagenetic overprinting of the barium signal occurs in sulfate depleted
sediments by dissolution of barite. Examples from selected sites in the Atlantic Ocean show that
barium may be a reliable proxy in this part of the world ocean to assess changes in ocean productivity,
whereas other proxies are restricted to certain sedimentary environments. Recent studies suggest
that for the oligotrophic areas of the Atlantic Ocean barium might be a more reliable tracer for past
productivity than organic carbon. This is attributed to the action of oxidation fronts which resulted
in a very efficient degradation of the organic matter initially present within the sediment. Nevertheless,
quantitative paleoproductivity reconstructions are based on regional studies and future investigations
must be carried out in a range of environments before a worldwide application can be obtained.
Introduction
The role of oceanic productivity in the
biogeochemical cycle of carbon has been reinforced by studies dealing with the variations of atmospheric CO 2 measured in ice cores (Berner et
a!. 1979; Bamola et a!. 1987). Glacial CO 2 -decrease is suggested as a forcing mechanism of ice
volume fluctuations (Shackleton and Pisias 1985).
In turn, ice-age changes in atmospheric CO 2 could
have resulted from changes in surface productivity of the oceans (Berger et a!. 1989). Thus the
marine paleoproductivity record provides a useful
tool to reconstruct the Earth's climate system.
Since components and elements of marine biological systems are easily recycled within the water column, or at the water-sediment interface, any
remaining productivity signal is highly diminished
and biased. The use of calcium carbonate, organic
carbon and opal as tools for paleoproductivity reconstructions has suffered from the common problem of distinguishing between preservation and productivity signals. As a consequence reliable
geochemical proxies for biological productivity,
which are well-preserved in deep-sea sediments,
have been searched. The evidence of a positive
correlation of barium, a highly refractive chemical
species, and productivity in surface waters
(Goldberg and Arrhenius 1958; Dehairs et a!. 1980;
Schmitz 1987; Bishop 1988) presents the possibilFrom FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examplesfrom the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 345-364
Limitations of Application
F.X. Gingele*l, M. ZabeF, S. Kasten 2 , W.J. Bonn 3 and C.C. Niimberg 4
lInstitutfur Ostseeforschung, SeestraJ3e 15, D-18119 Rostock-Warnemunde, Germany
2Universittit Bremen, Fachbereich Geowissenschaften, Postfach 330440,
D-28334 Bremen, Germany
3 Alfred-Wegener-Institutfur Polar- und Meeresforschung, Postfach 12 0161,
D-27515 Bremerhaven, Germany
4Geomar, Marine Umweltgeologie, WischhofstraJ3e 1-3, D-24148 Kiel, Germany
*corresponding author (e-mail):Jranz.gingele@io-warnemuende.de
Abstract: The obvious link between sedimentary barium and past and present ocean productivity
has propagated numerous studies on this tracer in the past years. In this paper a summary is given
on what is known of the generation of the barium signal and its link to the flux of organic carbon. We
describe procedures to assess barium contents, distinguish biogenic from detrital barium and calculate
barium accumulation rates. Two approaches to estimate absolute paleoproductivity rates from barium
contents are described and compared. A considerable part of the paper is dedicated to synsedimentary
and early diagenetic constraints involved in the application of the barium method. It is demonstrated
that the most significant diagenetic overprinting of the barium signal occurs in sulfate depleted
sediments by dissolution of barite. Examples from selected sites in the Atlantic Ocean show that
barium may be a reliable proxy in this part of the world ocean to assess changes in ocean productivity,
whereas other proxies are restricted to certain sedimentary environments. Recent studies suggest
that for the oligotrophic areas of the Atlantic Ocean barium might be a more reliable tracer for past
productivity than organic carbon. This is attributed to the action of oxidation fronts which resulted
in a very efficient degradation of the organic matter initially present within the sediment. Nevertheless,
quantitative paleoproductivity reconstructions are based on regional studies and future investigations
must be carried out in a range of environments before a worldwide application can be obtained.
Introduction
The role of oceanic productivity in the
biogeochemical cycle of carbon has been reinforced by studies dealing with the variations of atmospheric CO 2 measured in ice cores (Berner et
a!. 1979; Bamola et a!. 1987). Glacial CO 2 -decrease is suggested as a forcing mechanism of ice
volume fluctuations (Shackleton and Pisias 1985).
In turn, ice-age changes in atmospheric CO 2 could
have resulted from changes in surface productivity of the oceans (Berger et a!. 1989). Thus the
marine paleoproductivity record provides a useful
tool to reconstruct the Earth's climate system.
Since components and elements of marine biological systems are easily recycled within the water column, or at the water-sediment interface, any
remaining productivity signal is highly diminished
and biased. The use of calcium carbonate, organic
carbon and opal as tools for paleoproductivity reconstructions has suffered from the common problem of distinguishing between preservation and productivity signals. As a consequence reliable
geochemical proxies for biological productivity,
which are well-preserved in deep-sea sediments,
have been searched. The evidence of a positive
correlation of barium, a highly refractive chemical
species, and productivity in surface waters
(Goldberg and Arrhenius 1958; Dehairs et a!. 1980;
Schmitz 1987; Bishop 1988) presents the possibilFrom FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examplesfrom the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 345-364