Soil Science and Soil Protection, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 3, 06120, Halle (Saale), Germany.
Sci Rep. 2020 Jul 8;10(1):11225. doi: 10.1038/s41598-020-68042-x.
Growing evidence of silicon (Si) playing an important role in plant health and the global carbon cycle triggered research on its biogeochemistry. In terrestrial soil ecosystems, sorption of silicic acid (HSiO) to mineral surfaces is a main control on Si mobility. We examined the competitive sorption of Si, dissolved organic matter, and phosphorus in forest floor leachates (pH 4.1-4.7) to goethite, in order to assess its effects on Si mobility at weathering fronts in acidic topsoil, a decisive zone of nutrient turnover in soil. In batch sorption experiments, we varied the extent of competition between solutes by varying the amount of added goethite (α-FeOOH) and the Si pre-loading of the goethite surfaces. Results suggest weaker competitive strength of Si than of dissolved organic matter and ortho-phosphate. Under highly competitive conditions, hardly any dissolved Si (< 2%) but much of the dissolved organic carbon (48-80%) was sorbed. Pre-loading the goethite surfaces with monomeric Si hardly decreased the sorption of organic carbon and phosphate, whereas up to about 50% of the Si was released from surfaces into solutions, indicating competitive displacement from sorption sites. We conclude sorption competition with dissolved organic matter and other strongly sorbing solutes can promote Si leaching in soil. Such effects should thus be considered in conceptual models on soil Si transport, distribution, and phytoavailability.
越来越多的证据表明，硅（Si）在植物健康和全球碳循环中发挥着重要作用，这促使人们对其生物地球化学进行了研究。在陆地土壤生态系统中，硅酸（HSiO）在矿物表面的吸附是控制硅迁移的主要因素。我们研究了森林地表层淋溶液（pH 值为 4.1-4.7）中硅、溶解有机物和磷对针铁矿的竞争吸附，以评估其对酸性表土风化前沿硅迁移的影响，这是土壤养分转化的关键区域。在批量吸附实验中，我们通过改变添加针铁矿（α-FeOOH）的量和针铁矿表面的 Si 预加载量来改变溶质之间的竞争程度。结果表明，硅的竞争强度弱于溶解有机物和正磷酸盐。在高度竞争的条件下，几乎没有溶解的 Si（<2%），但大部分溶解的有机碳（48-80%）被吸附。将针铁矿表面预先加载单体 Si 几乎不会减少有机碳和磷酸盐的吸附，而高达约 50%的 Si 从表面释放到溶液中，表明从吸附位发生了竞争取代。我们得出结论，与溶解有机物和其他强吸附溶质的吸附竞争可以促进土壤中 Si 的淋溶。因此，在关于土壤 Si 迁移、分布和植物有效性的概念模型中应考虑这些影响。
