Ge/Si ratios of plant phytoliths have been widely used to trace biogeochemical cycling of Si. However, until recently, information on how much of the Ge and Si transferred from soil to plants is actually stored in phytoliths was lacking. The aim of the present study is to (i) compare the uptake of Si and Ge in three grass species, (ii) localize Ge and Si stored in above-ground plant parts and (iii) evaluate the amounts of Ge and Si sequestrated in phytoliths and plant tissues. Mays ( Zea mays ), oat ( Avena sativa ) and reed canary grass ( Phalaris arundinacea ) were cultivated in the greenhouse on soil and sand to control element supply. Leaf phytoliths were extracted by dry ashing. Total elemental composition of leaves, phytoliths, stems and roots were measured by ICP-MS. For the localization of phytoliths and the determination of Ge and Si within leaf tissues and phytoliths scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS) was used. The amounts of Si and Ge taken up by the species corresponded with biomass formation and decreased in the order Z. mays > P. arundinacea , A. sativa . Results from LA-ICP-MS revealed that Si was mostly localized in phytoliths, while Ge was disorderly distributed within the leaf tissue. In fact, from the total amounts of Ge accumulated in leaves only 10% was present in phytoliths highlighting the role of organic matter on biogeochemical cycling of Ge and the necessity for using bulk Ge/Si instead of Ge/Si in phytoliths to trace biogeochemical cycling of Si.

中文翻译：

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锗（Ge）在禾本科植物组织中的积累不仅仅由其掺入植硅体驱动

植物植硅体的 Ge/Si 比率已被广泛用于追踪 Si 的生物地球化学循环。然而，直到最近，关于从土壤转移到植物中的锗和硅有多少实际上储存在植硅体中的信息还缺乏。本研究的目的是 (i) 比较三种草种对 Si 和 Ge 的吸收，(ii) 定位储存在地上植物部分的 Ge 和 Si，以及 (iii) 评估在植硅体和植物组织。在温室中用土壤和沙子种植五月（Zea mays）、燕麦（Avena sativa）和金丝雀草（Phalaris arundinacea）以控制元素供应。通过干灰化提取叶植硅体。通过 ICP-MS 测量叶子、植硅体、茎和根的总元素组成。使用扫描电子显微镜 (SEM)、能量色散 X 射线光谱 (EDX) 和激光烧蚀电感耦合质谱 (LA-ICP-MS) 来定位植硅体和测定叶组织和植硅体中的 Ge 和 Si。物种吸收的 Si 和 Ge 量与生物量形成相对应，并以 Z. mays > P. arundinacea、A. sativa 的顺序减少。LA-ICP-MS 结果表明，Si 主要集中在植硅体中，而 Ge 则在叶组织中无序分布。事实上，从叶子中积累的 Ge 总量来看，植硅体中只有 10% 存在，这突出了有机物对 Ge 生物地球化学循环的作用，以及在植硅体中使用块状 Ge/Si 代替 Ge/Si 来追踪生物地球化学循环的必要性Si的。