龙感湖稀土元素的地球化学特征

采用液-液萃取法,连续提取法和ICP-MS测试技术,对龙感湖不同季节水和颗粒物中稀土元素进行研究.结果表明,龙感湖的溶解态稀土含量极低,稀土总含量(ΣREE)在3.14～129.81ng/kg之间,且季节性变化明显.龙感湖溶解态稀土元素表现出平坦型的页岩配分模式,这是由于在草型湖泊中溶解态稀土主要以吸附在微细胶体上的形式存在,水粒相互作用在这个过程中起主要控制作用.悬浮物中的稀土含量顺序为:残渣态>>Fe-Mn结合态>>有机态和AEC态,颗粒物中稀土元素主要以残渣态形式存在.Fe-Mn结合态、有机态和AEC态的页岩配分模式为中稀土富集,残渣态的页岩配分模式为平坦型.这说明中稀土与轻重稀土相比具有更强的潜在地球化学活性,但在龙感湖的环境中的迁移能力相对轻重稀土来说较弱.

Geochemical character of rare earth elements in Longgan lake, East of China

The rare earth elements(REEs)in Longgan lake is studied by the solvent extraction or sequential extraction procedure and the Inductively coupled plasma mass spectrometry(ICP-MS)determination. The contents of the dissolved REEs in the lake vary widely from 35.14 to 129.81 ng/kg. The dissolved REEs have a flat shale-normalized pattern,this is because the dissolved REEs are mainly presence in the fine colloidal phase(as a result of 0.22μm filtration)in a macrophyte lake. The amount of REEs in the sequential extracted four fractions obeys the following order:residual>bound Fe-Mn oxides>>adsorbed-exchangeable-carbonate(AEC)or bound organic matter. The partitioning characteristics of REEs in the suspended matter are quite similar,with the main amount in residual forms. The normalized patterns of REEs in AEC,bound organic matter and Fe-Mn oxides are same,with middle REEs enrichment,but the residual forms have a flat pattern. The middle REEs are more difficult to be transferred than other REEs in the water of Longgan lake,but these have more potential activities.