Unambiguous evidence of old soil carbon in grass biosilica particles
Unambiguous evidence of old soil carbon in grass biosilica particles
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DOI：
10.5194/bg-13-1269-2016
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发表时间：
2016-03
期刊：
影响因子：
4.9
通讯作者：
P. Reyerson;A. Alexandre;A. Harutyunyan;Rémi Corbineau;H. M. D. L. Torre;F. Badeck;L. Cattivelli;G. Santos
中科院分区：
文献类型：
--
作者：
P. Reyerson;A. Alexandre;A. Harutyunyan;Rémi Corbineau;H. M. D. L. Torre;F. Badeck;L. Cattivelli;G. Santos
植物生物硅颗粒（植硅石）含有少量的碳，称为phytC。基于phytC是光合作用起源和一个封闭系统的假设，最近有人声称来自几种重要的农业单子叶植物的植硅体在大气CO2封存中起着重要的作用。然而，异常phytC放射性碳（14 C）日期建议的贡献，从非光合来源phytC。在这里，我们解决这个非光合作用源假说使用比较同位素测量（14 C和δ 13 C）的phytC，植物组织，大气CO2，和土壤有机质。国家的最先进的方法保证植硅石的纯度，而顺序分步燃烧揭示了复杂的化学-热分解特性的phytC。虽然光合作用是植物组织中碳的主要来源，但已发现phytC部分来自可存在数千年的土壤碳。事实上，phytC是不是唯一的光合C构成限制phytC的有用性，无论是作为一个约会的工具，或作为一个重要的汇的大气CO2。此外，还需要进一步的实验来研究SOM衍生的C如何进入根部并在植物生物硅中积累，以更好地了解高等植物中硅生物矿化过程的机理过程。
Plant biosilica particles (phytoliths) contain small amounts of carbon called phytC. Based on the assumptions that phytC is of photosynthetic origin and a closed system, claims were recently made that phytoliths from several agriculturally important monocotyledonous species play a significant role in atmospheric CO 2 sequestration. However, anomalous phytC radiocarbon (14 C) dates suggested contributions from a non-photosynthetic source to phytC. Here we address this non-photosynthetic source hypothesis using comparative isotopic measurements (14 C and δ 13 C) of phytC, plant tissues, atmospheric CO 2 , and soil organic matter. State-of-the-art methods assured phytolith purity, while sequential stepwise-combustion revealed complex chemical-thermal decomposability properties of phytC. Although pho-tosynthesis is the main source of carbon in plant tissue, it was found that phytC is partially derived from soil carbon that can be several thousand years old. The fact that phytC is not uniquely constituted of photosynthetic C limits the usefulness of phytC either as a dating tool or as a significant sink of atmospheric CO 2. It additionally calls for further experiments to investigate how SOM-derived C is accessible to roots and accumulates in plant biosilica, for a better understanding of the mechanistic processes underlying the silicon biomineralization process in higher plants.