乌江流域沉积岩风化过程中稀土元素的富集与释放

以乌江流域石灰岩、白云质灰岩、白云岩、硅质岩、页岩和砂岩等沉积岩的13条风化剖面为对象，运用R型分层聚类分析和质量平衡计算方法，研究了这些岩石风化过程中稀土元素（REE）的富集与释放及其对植物生长和河水REE分布的影响，目的是为河水物质来源研究和为农业生产提供依据。结果表明：（1）乌江流域石灰土中REE的富集程度显著高于各自母岩、黄壤、上陆壳（UCC）、中国土壤（CS）和世界土壤（WS）；（2）沉积岩风化过程中REE的富集特征和机制可能与母岩中REE分布特征以及风化剖面中有机质、铁（氢）氧化物和粘土矿物的吸附有关；（3）沉积岩风化过程中释放的REE可为植物吸收利用；（4）石灰岩等沉积岩风化过程中REE和F。等元素的释放对河水溶解态REE的分布有重要影响。

Enrichment and Release of Rare Earth Elements during Weathering of Sedimentary Rocks in Wujiang Catchments

Thirteen weathering profiles of sedimentary rocks such as limestone,dolomitic limestone,dolomite,silicalite,black shale and purple sandrock from Wujiang catchments were selected for study on enrichment and release behavior of rare earth elements(REE) during weathering,and in its impact on plant growth and riverine REE distribution in the catchments with methods of hierachical cluster analysis and mass balance calculation in order to set a basis for riverine material source research and agricultural production.The results show that the enrichment degree of REE in calcareous soils from the Wujiang catchments is much higher than that of limestone,yellow soil,upper continental crust(UCC),China soil(CS) and world soil(WS).The ability of enrichment and release of REE is partly controlled by distribution of REE in bedrocks,contents and adsorption ability of organic matters,clay minerals and Fe-oxides/hydroxides in weathering profiles.The REE released from weathering of carbonate rocks and clastic rocks can be absorbed and utilized by local plants.Our results also reveal that release of REE and Fe mainly from weathering of carbonate rocks and partly from clastic rocks exerts an important control on riverine REE distribution.