水体溶解氧中三氧同位素测试技术与应用进展

Progress of Analytical Techniques and Application of Triple Oxygen Isotopes in Dissolved Oxygen

  • 摘要: 氧是地球生态系统中重要元素之一,其稳定同位素包括16O、17O和18O。由于氧稳定同位素组成(δ17O、δ18O)在不同的生物地球化学反应中具有不同的分馏模式,因此常被作为生物地球化学循环的示踪剂。水体溶解氧(DO)稳定同位素可用于示踪研究水团混合、氧元素的源汇平衡等。相比于18O,17O自然丰度较低,前处理以及质谱分析过程中都极易受到空气干扰,导致目前有关δ17O的研究尚十分有限。随着双路进样质谱测试技术的不断发展,δ17O可以被精确的测定,但前处理过程耗时耗力,效率更高的连续流进样质谱则由于难以避免空气干扰而导致精度不足。结合溶解氧的稳定同位素δ17O和δ18O(TOI)在生物过程和化学过程中的不同分馏模式,为估算水体初级生产力提供了全新的思路,也大大降低了传统方法中的误差。同时,借助冰芯中保存的古大气可以推断古气候演化过程。三氧同位素在生态学、环境科学、气候学以及海洋科学等领域的应用价值不断被挖掘,本文回顾了近年来水体DO稳定同位素分析测试技术的发展历程,重点综述三氧同位素在初级生产力估算及古气候演化中的科学应用,并展望了三氧同位素未来发展趋势。

     

    Abstract: Oxygen is one of the essential elements in Earth's ecosystem, with stable isotopes including δ16O, δ17O, and δ18O. The composition of oxygen stable isotopes (δ17O, δ18O) exhibits different fractionation patterns in various biogeochemical reactions, making them useful as tracers for biogeochemical cycles. The stable isotopes of dissolved oxygen (DO) in water bodies can be used to trace water mass mixing and the source-sink balance of oxygen elements. Compared to 18O, 17O has a lower natural abundance and is highly susceptible to air interference during sample preparation and mass spectrometry analysis. Currently, research on δ17O is still quite limited. With the continuous development of dual-inlet mass spectrometry technology, δ17O can now be accurately measured, but the preparation process is time-consuming and labor-intensive. Continuous flow injection mass spectrometry offers higher efficiency but suffers from reduced precision due to unavoidable air interference. Combining the different fractionation patterns of δ17O and δ18O (TOI) in biological and chemical processes provides a new approach for estimating primary productivity in water bodies, avoiding errors in traditional methods. Additionally, ancient atmospheres preserved in ice cores can be used to infer paleoclimate evolution processes. The triple oxygen isotopes are increasingly being recognized for their value in fields such as ecology, environmental science, climatology, and marine science. This paper reviews the recent advancements in DO stable isotope analysis techniques in water bodies, introduces the current research and developments of triple oxygen isotopes in primary productivity estimation and paleoclimate evolution, and discusses future directions and trends for triple oxygen isotopes.

     

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