上层海洋对大气的放射性碳抵消意味着快速降冰的二氧化碳释放
Kathryn A Rose1, Elisabeth L Sikes, Thomas P Guilderson
1Department of Geology, University of California, Davis, California 95616, USA.
Nature
|August 27, 2010
概括
海洋循环影响大气中的放射性碳水平. 这项研究揭示了南大洋上游在脱冰过程中释放的旧碳,影响放射性碳 (三角洲14C) 信号,并表明北太平洋碳库的贡献.
科学领域:
- 古代海洋学 古代海洋学
- 气候科学 气候科学
- 通过放射性碳测年法进行测年.
背景情况:
- 大气中的二氧化碳 (CO2) 和放射性碳 (14C) 水平受到海洋循环和碳交换的影响.
- 在最后一次冰河时期,低大气二氧化碳与高大气放射性碳相关,与深海二氧化碳储存有关.
- 冰河时代的结束导致二氧化碳的增加和大气14C三角洲的减少,这表明从深海释放的旧碳.
研究的目的:
- 调查西南太平洋和南大洋的表面和中间水域的放射性碳记录.
- 了解冰川 - 冰川间过渡期间碳释放的来源和途径.
- 重新评估南大洋在脱冰期碳循环变化中的作用.
主要方法:
- 在西南太平洋和南大洋的两个沉积物核心中对放射性碳 (Delta 14C) 的分析.
- 海洋Delta 14C记录与大气放射性碳数据的比较.
- 放射性碳信号与上游和生物生产力的证据的相关性.
主要成果:
- 在表面和中间水域观察到Delta 14C的显著下降,在大气变化之前和与之匹配.
- 南大洋的强化上升和海洋生产力与大气中的放射性碳减少相吻合.
- 通过南大洋上游释放的二氧化碳通过大气交换失去其耗尽的14C签名.
结论:
- 南大洋在脱冰期碳释放中的作用可能与之前的假设有所不同.
- 观察到的Delta 14C的耗尽表明来自北太平洋碳储库的贡献.
- 在南太平洋向北移动的浅水中,由于CO2脱气和生物吸收,显示了最小的耗尽-14C信号.
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