大硫同位素的分离不需要不成比例的分离.
Min Sub Sim1, Tanja Bosak, Shuhei Ono
1Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. mssim@mit.edu
概括
岩石中的硫同位素数据可能并不总是表明复杂的硫循环. 仅仅海洋细菌就能导致大量的硫-34耗尽,这挑战了以前对地球的解释.
科学领域:
- 地质化学 地质化学
- 微生物学 微生物学
- 地球历史 地球历史 地球历史
背景情况:
- 沉积硫化物和硫酸盐中的硫同位素是了解地球硫循环的关键.
- 硫化物中硫-34 ((34) S) 相对于硫酸盐的大量耗尽 (超过47‰) 通常表明与硫酸盐的减少一起存在硫不成比例.
研究的目的:
- 调查硫酸盐降解细菌是否可以单独产生大的硫同位素分离.
- 重新评估沉积硫同位素记录的解释,特别是关于早期地球环境.
主要方法:
- 在受控的实验室条件下培养一种海洋硫酸盐减少细菌.
- 在细菌产生的硫酸盐和硫化物中测量硫同位素成分 ((34) S).
主要成果:
- 海洋硫酸盐减少细菌的纯培养实现了高达66‰的显著硫-34耗尽.
- 这种分离仅通过硫酸盐还原而发生,没有细胞外硫氧化或不成比例.
结论:
- 古代沉积岩中的大量硫同位素分离并不仅仅表明硫不成比例或复杂的硫循环.
- 这些发现挑战了将这种分离作为原生代氧化事件或特定新陈代谢的明确代理的使用.
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