The geochemistry of rare earth elements (REEs) in riverine suspended particle matter (SPM) is an important role in indicating rock weathering processes. However, it has been unclear whether reservoirs can cause variations of geochemical characteristics and behaviors of REEs in SPM. In the present study, the REE contents and fractionations in SPM were investigated passing through cascade reservoirs in the Lancangjiang River. Large-sized reservoirs affected riverine temperature, pH, and dissolved oxygen, but did not affect electric conductance, total dissolved solids, and HCO₃⁻ concentration. Reservoirs affected the compositions of major elements in SPM by the redistribution of different minerals passing through dams. For the large-sized reservoirs, the REE contents in SPM showed a sharp decline (∑REE content decreased by 102 mg kg⁻¹ in the Xiaowan reservoir and decreased by 204 mg kg⁻¹ in the Nuozhadu reservoir) and then increased continuously after passing through dams. The variations of REE contents in SPM passing through dams are closely linked to the redistribution of clay minerals because clay minerals derived from feldspar weathering are the main carriers of REEs in SPM. The REE fractionation indexes, including the ratios of PAAS-normalized La/Yb (1.1–1.4), La/Sm (0.8–1.0), Sm/Yb (1.3–1.7), δCe (0.9–1), δEu (1.0–1.4), and δGd (1.3–1.5) in SPM slightly varied along the flow direction of the main stream and were not affected by dams. These results indicated that cascade reservoirs can affect REE contents in SPM by the redistribution of clay minerals when riverine water passes through dams, but cannot cause REE fractionations.

河流悬浮颗粒物 (SPM) 中稀土元素 (REE) 的地球化学在指示岩石风化过程中起着重要作用。然而，目前尚不清楚储层是否会导致 SPM 中 REE 的地球化学特征和行为发生变化。在本研究中，通过澜沧江梯级水库研究了 SPM 中的 REE 含量和分馏。大型水库影响河流温度、pH 和溶解氧，但不影响电导率、总溶解固体和 HCO ₃ ^-浓度。水库通过大坝不同矿物的重新分布影响了 SPM 中主要元素的组成。对于大型水库，SPM 中 REE 含量呈急剧下降趋势（小湾水库 ∑REE 含量下降 102 mg kg ^-1，糯扎渡水库 ∑REE 含量下降 204 mg kg ^-1）后继续上升通过水坝。流经大坝的 SPM 中 REE 含量的变化与粘土矿物的重新分布密切相关，因为长石风化衍生的粘土矿物是 SPM 中 REE 的主要载体。REE分馏指标，包括PAAS归一化La/Yb（1.1-1.4）、La/Sm（0.8-1.0）、Sm/Yb（1.3-1.7）、δ Ce（0.9-1）、δSPM中的Eu（1.0-1.4）和δGd（1.3-1.5）沿干流流向略有变化，不受大坝的影响。这些结果表明，梯级水库可以通过河流水流过大坝时粘土矿物的重新分布来影响SPM中REE含量，但不会引起REE分馏。