Rice plants assimilate both silicon (Si) and arsenic (As) from the soil solution and accumulate these elements in their tissues. While Si has been known as a major material that builds up a so-called phytolith structure throughout the plant body, the fate of As in rice plants is not fully understood. This study aims to clarify the possible encapsulation of As into the phytolith structure in rice straw or rice straw ash and to evaluate the dissolution properties of the encapsulated As. Rice straw contains up to ~12 mg As kg⁻¹, which highlights this material as a sink and source of As that needs to be taken into account. The intensified heat treatments of rice straw could lead to an enrichment of As in the burned products, from which As is likely associated more tightly with the phytolith structure. We observed strong correlations of released As and Si, demonstrating that the release of As is tightly controlled by the dissolution of phytoliths. This means that phytoliths can contribute to the soil As pool, but this As source might be obscured because it is recalcitrantly lodged within the phytolith structure. This finding serves as a basis for further assessing the role of phytolith-encapsulated As rice paddy systems and for developing proactive practices to manage As-tainted straw.

水稻植物从土壤溶液中吸收硅（Si）和砷（As），并在组织中积累这些元素。尽管人们已经知道硅是在整个植物体内建立所谓的植硅体结构的主要材料，但人们对水稻中砷的命运还没有完全了解。这项研究的目的是弄清砷可能在稻草或稻草灰中的植石结构中的包封，并评价包封的As的溶出特性。稻草含有高达〜12 mg As kg ^-1，突出显示了这种材料是砷的吸收剂和来源。稻草的强化热处理可能导致燃烧产物中As的富集，As可能与植物石板结构紧密相关。我们观察到了释放的砷和硅的强相关性，表明砷的释放受到植石溶解的严格控制。这意味着植硅石可以促进土壤As池，但是这种As源可能会被掩盖，因为它顽固地滞留在植硅石结构中。这一发现为进一步评估植石剂包埋的稻田系统的作用和发展主动措施管理受污染稻草提供了基础。