赣南小流域水体中稀土元素的地球化学特征

本文以赣南小流域水体为研究对象,利用VG Axiom高分辨多接受双聚焦等离子体质谱仪测定了水体中溶解态稀土元素(DREE)的含量,分析了水体中DREE的分布分异机制,并探讨了稀土元素(REE)产生分异的原因.结果表明,赣南所有的采样区水体中Ce都表现为负异常,说明其在风化壳中少活化.受自然风化作用控制为主的水体相对于页岩除Ce亏损、Eu富集外产生的分异很小,其中Eu的正异常源于Eu富集矿物的优先溶解;蒸发盐矿影响下的水体相对于自然作用为主的水体DREE没有发生明显分异;受稀土矿影响的水体中重稀土元素(HREE)富集、Eu负异常的分布模式继承了稀土矿区风化壳的特征;赣州市下游干流水体中中稀土元素(MREE)富集、Eu负异常的分布模式主要是人为影响的结果.

Geochemical Characteristics of Rare Earth Elements in the Water Body of the Ganjiang River, Southern Jiangxi

Concentrations of dissolved rare earth elements(DREE) were measured in the upper reaches of the Ganjiang River in southern Jiangxi Province.The authors analyzed the distribution and fractionation of DREE in the water,and discussed the origins of the rare earth elements(REE) signatures.The results show that Ce has negative anomalies in the valley of southern Jiangxi,suggesting less mobilization of Ce in the weathering profile.The water controlled by natural weathering has no obvious REE fractionation except for Ce and Eu.The positive Eu anomalies in this area are mainly determined by the preferential dissolution of Eu-enriched minerals.The DREE in the water affected by the evaporable salt deposit are lowly fractionated in comparison with those in the natural settings.The heavy REE(HREE)-enriched negative Eu anomalistic patterns in the water body affected by rare earth deposit have inherited characteristics of the weathering crust.Middle REE(MREE)-enriched negative Eu anomalistic patterns in the mainstream water are probably related to anthropogenic factors.