2015年10月
Seasonal variability of O-18 and C-13 of planktic foraminifera in the Bering Sea and central subarctic Pacific during 1990-2000
PALEOCEANOGRAPHY
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- 巻
- 30
- 号
- 10
- 開始ページ
- 1328
- 終了ページ
- 1346
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1002/2015PA002801
- 出版者・発行元
- AMER GEOPHYSICAL UNION
We evaluated a 10year time series of O-18 and C-13 records from three planktic foraminifers (Neogloboquadrina pachyderma, Globigerina umbilicata, and Globigerinita glutinata) in the Bering Sea and central subarctic Pacific with a focus on their responses to environmental changes. Foraminiferal O-18 followed the equilibrium equation for inorganic calcite, with species-specific equilibrium offsets ranging from nearly zero (-0.02 for N.pachyderma and -0.01 for G.umbilicata) to -0.16 (G.glutinata). Equilibrium offsets in our sediment trap samples were smaller than those from plankton tow studies, implying that foraminiferal O-18 was modified by encrustation during settling. Habitat/calcification depths varied from 35-55m (N.pachyderma and G.umbilicata) or 25-45m (G.glutinata) during warm, stratified seasons to around 100m during winter, when the mixed layer depth increases. Unlike O-18, foraminiferal C-13 showed species-specific responses to environmental changes. We found a dependency of C-13 in G.umbilicata on CO32- concentrations in ambient seawater that agreed reasonably well with published laboratory results, suggesting that C-13 of G.umbilicata is subject to vital effects. In contrast, C-13 of N.pachyderma and G.glutinata are likely affected by other species-specific biological activities. Seasonal flux patterns reveal that fossil records of N.pachyderma and G.glutinata represent annual mean conditions, whereas that of G.umbilicata most likely indicates those of a specific season. Because none of these three taxa was abundant from December to February, their fossil records likely do not reflect isotope signals from cold seasons.
- リンク情報
- ID情報
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- DOI : 10.1002/2015PA002801
- ISSN : 0883-8305
- eISSN : 1944-9186
- Web of Science ID : WOS:000366061400007