We studied the effects of preferential flow on weathering of primary minerals in well-drained, sandy Spodosols (Podzols) in northern Michigan, USA. Preferential flow in these soils is manifested as deep eluvial/illuvial tongues. We hypothesized that sands in the best developed (strong) tongues would be more weathered than in tongues that are short and/or thin (weak tongues), and especially so when compared to pedons that lack tongues (off-tongues). Across these three types of morphologies, we sampled at a variety of depths and horizons to establish correspondence between tongue strength and primary mineral weathering, using (Ba+Rb)/Sr data from a portable xrf instrument as a weathering surrogate. Soil acidity and primary mineral weathering vary predictably: strong tongues > weak tongues > off-tongues. This trend continues well below the profile, as BC and C horizons below strong tongues are also weathered, even though morphological indicators of pedogenesis and weathering here are not present. E horizons, which experience the most cumulative percolation of soil water, are strongly weathered, regardless whether they are located above a tongue, or not. Thus, we conclude that the cumulative percolation of acidic water, rich in organo-metallic compounds, drives weathering in these soils, even at depths to which the organics and illuvial materials have not yet reached. That is, the effects of podzolization and weathering extend well below what is morphologically considered the profile. Our data indicate that (a) coatings of organo-metallic substances in B horizons do not “protect” the underlying grains from dissolution and weathering-related reactions, and (b) pedogenesis and weathering can extend far below the profile, beneath areas of preferential flow.

我们研究了优先流动对美国密歇根州北部排水良好，沙质的Spodosols（Podzols）中主要矿物风化的影响。在这些土壤中的优先流动表现为深层的坡口/坡口舌。我们假设，最发达（强壮）的舌头中的沙粒比短和/或薄（弱舌头）的沙粒更耐候，尤其是与缺少舌头的舌头（异舌）相比，风沙更为明显。在这三种类型的形态学中，我们使用便携式xrf仪器的（Ba + Rb）/ Sr数据作为风化替代物，在各种深度和水平进行采样，以建立舌头强度与主要矿物风化之间的对应关系。可以预见的是，土壤酸度和主要矿物风化作用会发生变化：强舌>弱舌>断舌。这种趋势持续到轮廓之下，因为强舌下的BC和C层也被风化，即使此处没有形成成岩作用和风化的形态指标。经历最多的土壤水渗透的E层被强烈风化，无论它们是否位于舌头上方。因此，我们得出结论，富含有机金属化合物的酸性水的累积渗透，甚至在尚未达到有机物和土壤材料的深度下，也会在这些土壤中推动风化作用。也就是说，过饱和作用和风化作用的影响远低于形态学上认为的分布。