Silicon (Si) is found in various fractions of soil, depending on the pedogenic processes of the environment. Dissolved Si (DSi) is adsorbed in soil particles or leaches through the soil profile into the groundwater. The objective of this study is to quantify, using the sequential extraction method, the different Si fractions in volcanic ash soils on Jeju Island that may affect groundwater Si content, and to compare them with those in forest soils on mainland Korea. Most of the Si in these soils was bound in unavailable forms as primary and secondary silicates. The second largest proportion of Si in the non-Andisols of Jeju Island and Korean mainland soils was accumulated as amorphous Si, while in the Andisols of Jeju Island, the second most significant Si fraction was in pedogenic oxides and hydroxides. The products of these soil formations were short-range-order minerals such as allophane (4–40%). The adsorbed Si concentration tended to increase at lower depths in Andisols (100–1400 mg kg−1) and was approximately five times higher than that in non-Andisols. The results indicate that Si is more soluble in the Andisols of high precipitation regions and that Andisols on Jeju Island potentially affect groundwater Si concentration.

中文翻译：

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可能影响韩国济州岛地下水硅含量的火山灰土中可溶性硅的硅分馏

硅 (Si) 存在于土壤的各个部分，具体取决于环境的成土过程。溶解硅 (DSi) 被吸附在土壤颗粒中或通过土壤剖面渗入地下水中。本研究的目的是使用连续提取方法量化济州岛火山灰土壤中可能影响地下水硅含量的不同硅成分，并将它们与韩国大陆森林土壤中的硅成分进行比较。这些土壤中的大部分硅以原生和次生硅酸盐的形式以不可利用的形式结合。济州岛和韩国大陆的非安地溶胶中第二大比例的硅以无定形硅的形式积累，而在济州岛的安地溶土中，第二大比例的硅以成土氧化物和氢氧化物的形式积累。这些土壤形成的产物是短程矿物，如水铝石（4-40%）。吸附的硅浓度在安地溶胶（100-1400 mg kg-1）的较低深度处趋于增加，并且比非安地溶胶高约五倍。结果表明，Si 更易溶于高降水区的 Andisol，济州岛上的 Andisol 可能会影响地下水 Si 浓度。