Assessing the reliability of paleochemical tracers: barium uptake in the shells of planktonic foraminifera

The trace metal composition of foraminiferal shells preserved in deep-sea sediments is a critical source of data used in reconstructing the physical and chemical characteristics of ancient oceans. However, paleoceanographic information derived from these tracers is limited by the accuracy with which calcite shells record ambient seawater chemistry and the question of whether changing environmental conditions or interspecific differences affect shell chemistry. Experiments with living foraminifera are one of the most direct ways to quantitatively evaluate the relationship between shell and seawater chemistry and the influence, if any, of environmental variables. Here we present results from laboratory experiments on the living planktonic foraminifers Globigerina sacculifer and Orbulina universa that demonstrate that precipitated shells provide an accurate record of seawater barium, a tracer used in reconstructing nutrient and alkalinity distributions in past oceans. On the basis of culturing data at 29°C, 36.7‰ salinity, the best estimate of the partition coefficient D relating foraminifera shell Ba/Ca to seawater Ba/Ca is 0.147 ± 0.004. Data show that when environmental conditions are held constant, there is no significant variability in Ba uptake between individual shells of one or both species. Results also demonstrate that temperature varying over a 7°C range and salinity varying over a 3‰ range do not appreciably influence Ba uptake.

[1]  D. Lea.  Constraints on the alkalinity and circulation of glacial circumpolar deep water from benthic foraminiferal barium , 1993 .

[2]  L. M. Walter,et al.  Fluoride content of foraminiferal calcite: Relations to life habitat, oxygen isotope composition, and minor element chemistry , 1993 .

[3]  J. Cole,et al.  Surface ocean variability at Galapagos from 1936–1982: Calibration of geochemical tracers in corals , 1992 .

[4]  D. Lea,et al.  Experimental determination of barium uptake in shells of the planktonic foraminifera Orbulina universa at 22°C , 1992 .

[5]  M. Hannington,et al.  Cores drilled into active smokers on Juan de Fuca ridge , 1992 .

[6]  E. Boyle,et al.  Barium in planktonic foraminifera , 1991 .

[7]  E. Boyle,et al.  Further evidence for a link between Late Pleistocene North Atlantic surface temperatures and North Atlantic deep-water production , 1990 .

[8]  E. Boyle,et al.  Foraminiferal reconstruction of barium distributions in water masses of the glacial oceans , 1990 .

[9]  E. Boyle,et al.  A 210,000-year record of barium variability in the deep northwest Atlantic Ocean , 1990, Nature.

[10]  M. Delaney.  Uptake of cadmium into calcite shells by planktonic foraminifera , 1989 .

[11]  E. Boyle,et al.  Coralline barium records temporal variability in equatorial Pacific upwelling , 1989, Nature.

[12]  E. Boyle,et al.  Barium content of benthic foraminifera controlled by bottom-water composition , 1989, Nature.

[13]  DOUGLAS F. Williams,et al.  Extracting environmental information from planktonic foraminiferal δ13C data , 1988, Nature.

[14]  E. Boyle.  Cadmium: Chemical tracer of deepwater paleoceanography , 1988 .

[15]  Eric R. Ziegel,et al.  Practical Statistics for Analytical Chemists , 1987 .

[16]  N. Pingitore.  Modes of Coprecipitation of Ba2+and Sr2+with Calcite , 1987 .

[17]  Edward A. Boyle,et al.  North Atlantic thermohaline circulation during the past 20,000 years linked to high-latitude surface temperature , 1987, Nature.

[18]  Edward A. Boyle,et al.  Comparison of Atlantic and Pacific paleochemical records for the last 215,000 years : changes in deep ocean circulation and chemical inventories , 1985 .

[19]  Steven L. Parker,et al.  Photosynthesis in the symbiotic planktonic foraminifer Orbulina universa, and its potential contribution to oceanic primary productivity , 1985 .

[20]  M. P. Eastman,et al.  The experimental partitioning of Ba2+ into calcite , 1984 .

[21]  E. Boyle.  Sampling statistic limitations on benthic foraminifera chemical and isotopic data , 1984 .

[22]  E. Boyle,et al.  Deep Circulation of the North Atlantic over the Last 200,000 Years: Geochemical Evidence , 1982, Science.

[23]  J. Edmond,et al.  On the barium data from the Atlantic GEOSECS expedition , 1977 .

[24]  C. Hemleben,et al.  Laboratory and field observations of living planktonic foraminifera , 1977 .

[25]  J. Erez,et al.  URANIUM IN FORAMINIFERAL CALCITE AS A RECORDER OF SEAWATER URANIUM CONCENTRATIONS , 1994 .

[26]  E. Boyle,et al.  Reply to the Comment by N. E. Pingitore Jr. on , 1993 .

[27]  N. Pingitore.  Comment on “Barium in planktonic foraminifera” by D. W. Lea and E. A. Boyle , 1993 .

[28]  E. Boyle,et al.  Factors controlling the fluoride content of planktonic foraminifera: An evaluation of its paleoceanographic applicability , 1993 .

[29]  E. Boyle.  Cadmium and delta13C Paleochemical Ocean Distributions During the Stage 2 Glacial Maximum , 1992 .

[30]  G. Klinkhammer,et al.  Determination of barium in marine waters by isotope dilution inductively coupled plasma mass spectrometry , 1990 .

[31]  J. Morse,et al.  Partition coefficients in calcite: Examination of factors influencing the validity of experimental results and their application to natural systems , 1990 .

[32]  D. Lea.  Foraminiferal and coralline barium as paleoceanographic tracers , 1990 .

[33]  M. J. Deniro,et al.  The influence of symbiont photosynthesis on the δ18O and δ13C values of planktonic foraminiferal shell calcite , 1987 .

[34]  T. Oomori,et al.  Measurements of distribution coefficients and barium between carbonate precipitate —Abnormally high values of distribution measured at early stages of carbonate of strontium and solution coefficients formation , 1971 .