Wang Lingqing, Han Xiaoxiao, Ding Shiming, Liang Tao, Zhang Yongyong, Xiao Jun, Dong Linlin, Zhang Haidong
Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2019 Jul 1;672:264-274. doi: 10.1016/j.scitotenv.2019.03.484. Epub 2019 Apr 2.
Geochemical properties of rare earth elements (REEs) have the potential to represent the provenance and depositional history of surface sediment in aquatic environments. In this study, both surface and core sediment samples were collected from Dongting Lake to investigate the distribution characteristics and source of REEs by combining the methodologies of geostatistics, positive matrix factorization (PMF) model, discriminant function (DF), and provenance index (PI) based on REEs geochemical parameters. The results indicated that the total REEs content in sediment samples ranged from 129.12 to 284.02 μg g, with the average REEs content calculated to be 197.95 μg g. Light REEs (LREEs) comprised >90% of the total REEs, indicating that there was an enrichment of LREEs in the sediment samples. The REEs of the surface sediment showed strong spatial variation, with relatively high values located in Eastern Dongting Lake and relatively lower levels in Western Dongting Lake. Moreover, the vertical distributions of ∑REEs, ∑LREEs and ∑HREEs at most sampling sites behaved similarly with rapid increase until about 6-8 cm, followed by a downward trend with some irregularities. The strong association between most REEs confirmed that they often have a positive correlation and co-existence in sediment. The PMF model revealed that most of the REEs in the surface sediment were derived from natural sources with some anthropogenic inputs also serving as contributing sources. The DF and PI results indicated that the REEs distribution pattern in the surface sediment of Dongting Lake was similar to that of the Yangtze River, suggesting that Yangtze River had been more of an influence on sediment loads than the upstream tributaries. This study highlights the broader applicability of the REEs tracing method in sediment transport processes and can provide new knowledge regarding source apportionment analysis of sediment-related contaminants in aquatic environments.
稀土元素（REEs）的地球化学性质有潜力反映水生环境中表层沉积物的物源和沉积历史。在本研究中，从洞庭湖采集了表层和柱状沉积物样本，通过结合基于稀土元素地球化学参数的地统计学、正定矩阵因子分解（PMF）模型、判别函数（DF）和物源指数（PI）方法，研究稀土元素的分布特征和来源。结果表明，沉积物样本中稀土元素的总含量在129.12至284.02μg/g之间，计算得出的稀土元素平均含量为197.95μg/g。轻稀土元素（LREEs）占稀土元素总量的90%以上，表明沉积物样本中存在轻稀土元素富集现象。表层沉积物中的稀土元素表现出强烈的空间变化，较高值位于东洞庭湖，较低值位于西洞庭湖。此外，大多数采样点的∑REEs、∑LREEs和∑HREEs的垂直分布情况相似，在约6 - 8厘米深度之前快速增加，随后呈下降趋势且有一些不规则变化。大多数稀土元素之间的强相关性证实它们在沉积物中通常呈正相关并共存。PMF模型显示，表层沉积物中的大多数稀土元素来自自然源，同时也有一些人为输入作为贡献源。DF和PI结果表明，洞庭湖表层沉积物中稀土元素的分布模式与长江相似，这表明长江对沉积物负荷的影响比上游支流更大。本研究突出了稀土元素示踪方法在沉积物输运过程中的更广泛适用性，并可为水生环境中与沉积物相关污染物的源解析分析提供新知识。
