对黄山景观流域径流中溶解态稀土元素进行了研究,以探讨其地球化学特征与物质来源.结果表明,其主要来源为岩石化学风化,其次为大气输入.稀土元素含量枯水期高于丰水期,与蒸发富集效应有关.流域源头稀土元素含量高、重稀土相对富集,中下游稀土含量低、轻稀土相对富集,反映了源头花岗岩到中下游沉积岩对其相应控制.流域水体中Ce为负异常,表现出对流经原岩如花岗岩的继承;Eu为正异常,归因于花岗岩中斜长石/钾长石等矿物的优先风化释放.Y/Ho比值在空间上存在分异,主要为流经岩性不同所致,季节性分异则受到了水/粒相互作用的影响.研究表明,黄山景观流域溶解态稀土元素来源与迁移受流经岩性尤其花岗岩的影响显著.
Geochemical behaviors of rare earth elements (REEs) in chemical weathering process of silicates have drawn much attention.The draining water of watershed at Northern Mount Huangshan (NMHW) were sampled in order to define sources and distribution of dissolved REEs,and to describe the factors that govern their mobility.The results showed that rock chemical weathering is the dominant source for REEs,and the atmospheric input is another important source.The dissolved REEs showed slightly seasonal and greatly spatial variations in contents.The evaporative enrichment of runoff leads to high content in the dry season.The source water displays high dissolved REEs content and enriches in HREE.However,the content in middle-lower reaches is low and shows enrichment of LREE.The major reason for these changes is spatial variation of draining primary rocks from granites to sedimentary rocks.Most water samples show negative Ce and positive Eu anomalies,respectively.The former is fact of inheritance with primary rocks and the latter appears to be a result of preferential weathering of feldspar minerals such as plagioclase,orthoclase in granites.The Y/Ho ratios display seasonal and spatial fractionations which are linked to water/particle interactions and spatial changes of primary rocks,respectively.This study demonstrates that the geochemical behaviors of dissolved REEs are significantly influenced by the primary rocks especially the granites in NMHW.
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