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Bomb signals in old Antarctic brachiopods

机译：旧南极腕足动物的炸弹信号

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摘要

Skeletal check-marks are commonly used to assess the age and growth of organisms. They are usually assumed to be formed annually. By using radiocarbon bomb signals to calibrate growth checks in shells of Antarctic brachiopods, we show that they were laid down with a sub-biennial periodicity. The data also indicate that low Southern Ocean ~(14)C signals are probably not caused by upwelling deep water, but are more probably due to reduced atmospheric supply and long-term radiocarbon deposition in ice. Articulate brachiopods dominate the macrofossil record from Cambrian times. They are sessile filter-feeders, present in all oceans of the world, and are classified as 'low-energy lifestyle' organisms. Growth-rate investigations, which are performed rarely, are typically based on analyses of bands in their calcium carbonate shell valves. All species with carbonate skeletons incorporate ~(14)C from the environment. Radiocarbon concentrations in oceans are low compared with atmospheric and terrestrial levels, because their dissolved carbon pool is around 60 times the atmospheric pool. Variability in oceanic signals has been used to indicate areas of upwelling water, and coral and bivalve mollusc skeletal signals to assess ~(14)C records in latitudes to 42 °N (ref. 4). Antarctic ~(14)C levels are especially low, posing problems when dating marine material. Age corrections up to 1,400 years are necessary for recent material, whereas around 400 years is typical elsewhere.
机译：骨骼检查标记通常用于评估生物的年龄和生长。通常假定它们是每年形成的。通过使用放射性碳炸弹信号校准南极腕足动物壳内的生长检查，我们发现它们的生长周期为每两年一次。数据还表明，南大洋〜（14）C信号低可能不是由深水上升引起的，而更可能是由于大气供应减少和冰中长期放射性碳沉积所致。口齿腕足在寒武纪的大型化石记录中占主导地位。它们是无柄滤食性动物，存在于世界所有海洋中，被归类为“低能耗生活方式”生物。很少进行的增长率研究通常基于对碳酸钙壳瓣膜中条带的分析。所有具有碳酸盐骨架的物种都从环境中吸收〜（14）C。与大气和陆地相比，海洋中的放射性碳浓度较低，因为它们的溶解碳库约为大气池的60倍。海洋信号的可变性已被用于指示上升水的区域，以及珊瑚和双壳类软体动物的骨骼信号来评估北纬至42°N的〜（14）C记录（参考文献4）。南极的〜（14）C水平特别低，与海洋物质约会时会出现问题。对于最新资料，必须进行长达1400年的年龄校正，而在其他地方通常需要约400年。

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  • 来源
    《Nature》 |1996年第6571期|p.207-208|共2页
  • 作者

    Lloyd S. Peck; Thomas Brey;

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  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
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