Trace/minor element:calcium ratios in cultured benthic foraminifera. Part I: Inter-species and inter-individual variability
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- 作者：Christopher J. Hintz ; Timothy J. Shaw ; G. Thomas Chandler ; Joan M. Bernhard ; Daniel C. McCorkle and Jessica K. Blanks
- 刊名：Geochimica et Cosmochimica Acta
- 出版年：2006
- 出版时间：15 April 2006
- 年：2006
- 卷：70
- 期：8
- 页码：1952-1963
- 全文大小：289 K
文摘
Trace/minor element signatures (DCd, DBa, DMg, and DSr) were measured in the tests (shells) of benthic foraminifera cultured in a trace-metal-concentration-controlled system. The culture system was constructed of inert materials and designed to limit microhabitat effects. This system ensured that variation observed in cultured foraminiferal element:calcium (TE/Ca) signatures was due to biologically mediated (vital) effects only. Two species, Bulimina aculeata and Rosalina vilardeboana, reproduced prolifically during two 4-to-8-month culture periods. In every case (i.e., for both species and each element), the inter-individual variability was larger than the analytical precision. Mean (±1 standard deviation) DE signatures for B. aculeata were: DCd: 1.5 ± 0.4, DBa × 10: 2.1 ± 0.7, DMg × 1000: 0.62 ± 0.15, and DSr × 10: 1.5 ± 0.1. Cultured B. aculeata DMg, calibrated from culture and core-top (live) field specimens, predicted temperatures within ±2.0 °C. The observed inter-individual variability from culture specimens was as large or larger than comparable results from core-top investigations. R. vilardeboana DCd signatures were significantly lower, while DBa, DMg, and DSr signatures were significantly higher than B. aculeata values. Since our culture system minimizes microhabitat variability, the variation in measured TE/Ca ratios suggests that biological processes are a significant factor in inter-individual and inter-species variability. Comparison of cultured and field-collected foraminiferal DBa signatures supports previous findings that pore-water chemistry is a major environmental influence on foraminiferal test chemistry.