长江下游与浙江主要河流枯水期悬浮物稀土元素组成研究

On the composition of rare earth elements of suspended substance in lower reach of the Yangtze River and main rivers in Zhejiang Province in dry season

  • 摘要: 基于2021年 10月至11月在长江下游及钱塘江、椒江和瓯江等浙江主要河流枯水期采集的64个悬浮物样品,分析研究了其粒度分布和稀土元素(REE)组成,讨论了各河悬浮物REE组成差异以及物源端元特征。结果显示,枯水期长江下游、钱塘江、椒江和瓯江悬浮物REE含量均值分别为209.52、173.64、211.86和228.70 mg/kg;北美页岩(NASC)标准化配分曲线明显向右倾,并有明显的Ce负异常特征。与前人所测数据相比,钱塘江和瓯江悬浮物REE含量明显较高;长江悬浮物REE和前人长江悬浮物/沉积物表现总体一致。从(La/Yb)NASC—(La/Gd)NASC图看,长江、钱塘江、椒江、瓯江之间有一定差别,可成为它们物源端元的判别指标;相对于历史沉积物数据,长江悬浮物REE比值分布范围较为集中,以悬浮物为对象研究河流物源端元比沉积物有更好的效果。

     

    Abstract: Sixty-four samples of suspended substance were collected in October–November, 2021 from the lower reaches of Yangtze River and major rivers in Zhejiang Province in dry season, from which the differences of distribution characteristics of rare earth elements (REEs) and provenance indication of the suspended substance were discussed. Results show that the average REE contents in the suspended substance from the lower reaches of the Yangtze River, Qiantang River, Jiaojiang River, and Oujiang River in dry season were about 209.52, 173.64, 211.86, and 228.70 mg/kg, respectively, and the contents of REEs of the Qiantang River and the Oujiang River were obviously higher than previous data. The normalized partition curve against the value of North American Shale Composition (NASC) was gentle in general and slightly incline to the right, with obvious MREE enrichment, which is consistent in overall with the previous studies of the Yangtze River and major rivers in Zhejiang Province. The diagrams of (La/Yb)NASC vs (La/G)NASC, the index of (La/Yb)NASC, and (La/Gd)NASC were used to distinguish provenance of the Yangtze River from rivers in Zhejiang Province. The distribution scope of (La/Yb)NASC and (La/Gd)NASC of suspended substance of this study is more concentrated than those of the historical data, which mean that suspended substance could be used for river provenance study.

     

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