Rare earth elements (REE) are sensitive tracers of rock-water interactions and soil formation processes. In this study, we investigated the REE concentration and distribution patterns for both bulk samples and acid leachable phase for a series of regolith and soil profiles developed on a deeply weathered granite hillslope in a subtropical climate. The exogenous input had little impact on the REE distributions on the studied hillslope. The REE distribution in the profiles was controlled by changes in the physical and chemical environmental parameters and mineral transformation during weathering. However, the specific mechanisms differed among the different weathering stages and profiles located at different positions along the slope. Among the environmental parameters, the profile redox state and acidity were the dominant factors controlling the REE behavior, with organic materials as the main regulators. A strong positive relationship between chemical index of alteration (CIA) and La/Yb was observed for the regolith samples, but the La/Yb ratio decreased upward from a depth of 120 cm (the bottom depth of the soil horizon) as the CIA value increased, suggesting a preference for light REE (LREE) fixation in kaolinite formed during the dissolution of feldspar; however, a conversion occurred during the subsequent pedogenesis period. The hilltop soil profile was characterized by the strongest LREE depletion and the highest positive Ce anomaly (~7.31–14.28), compared with other profiles down the hillslope (~0.84–2.78). The strongest LREE depletion on the hilltop profile JLN-S4 suggested a preference for LREE release resulting from the transformation of kaolinite to gibbsite, and the highest Ce anomaly indicates that Ce was fixed in a more oxidized environment within a well-drained profile. The hill foot profile JLN-S1 had the highest LREE leaching rate, but also the lowest heavy REE (HREE) leaching rate, which was ascribed to its lowest erosion rate, lowest pH value, and reductive conditions in a more hydromorphic zone down the hill. The releasing rates of REE calculated by a mass balance model at different positions along the catena ranged from 1395 to 14,379 μg m⁻²y⁻¹. All the observed REE fractionation regimes and weathering rate variations along the hillslope illustrated that topography-regulated hydrologic condition played a critical role in the release and migration of REE during granite weathering.

稀土元素 (REE) 是岩水相互作用和土壤形成过程的敏感示踪剂。在这项研究中，我们研究了亚热带气候下深风化花岗岩山坡上形成的一系列风化层和土壤剖面的大块样品和酸浸出相的 REE 浓度和分布模式。外源输入对所研究山坡上的 REE 分布几乎没有影响。剖面中的稀土元素分布受风化过程中物理和化学环境参数的变化和矿物转化的控制。但是，在斜坡不同位置的不同风化阶段和剖面的具体机制不同。在环境参数中，剖面氧化还原状态和酸度是控制 REE 行为的主要因素，有机材料是主要调节剂。风化层样品的化学蚀变指数 (CIA) 与 La/Yb 呈强正相关关系，但作为 CIA 值，La/Yb 比值从 120 cm 深度（土壤层的底部深度）向上下降增加，表明在长石溶解过程中形成的高岭石更倾向于轻稀土（LREE）固定；然而，在随后的成土期发生了转变。与山坡下的其他剖面（~0.84-2.78）相比，山顶土壤剖面的特征是最强的 LREE 消耗和最高的正 Ce 异常（~7.31-14.28）。山顶剖面 JLN-S4 上最强的 LREE 消耗表明，由于高岭石向三水铝石的转变，倾向于释放 LREE，最高的 Ce 异常表明 Ce 被固定在排水良好的剖面内更氧化的环境中。山脚剖面 JLN-S1 的 LREE 浸出率最高，但重稀土 (HREE) 浸出率最低，这归因于其最低的侵蚀率、最低的 pH 值和山下更水形带的还原条件. 质量平衡模型计算的沿线不同位置的 REE 释放率 山脚剖面 JLN-S1 的 LREE 浸出率最高，但重稀土 (HREE) 浸出率最低，这归因于其最低的侵蚀率、最低的 pH 值和山下更水形带的还原条件. 质量平衡模型计算的沿线不同位置的 REE 释放率 山脚剖面 JLN-S1 的 LREE 浸出率最高，但重稀土 (HREE) 浸出率最低，这归因于其最低的侵蚀率、最低的 pH 值和山下更水形带的还原条件. 质量平衡模型计算的沿线不同位置的 REE 释放率链式范围从 1395 到 14,379 μg m ^-2 y ^-1。沿山坡观察到的所有稀土元素分馏机制和风化速率变化表明，地形调节的水文条件在花岗岩风化过程中稀土元素的释放和迁移中发挥了关键作用。