沙塘川河西宁段表层沉积物重金属与稀土元素地球化学特征及其物源解析

Geochemical characteristics and provenance analysis of heavy metals and REE in surface sediments from Xining section of Shatangchuan River

选取青海省沙塘川河西宁段表层沉积物为研究对象,分析Cr等8种重金属的污染程度、潜在生态风险和物质来源以及稀土元素组成、分布特征和物质来源,并探讨稀土元素的控制因素。结果显示,重金属呈现轻度—中度污染状况,污染负荷程度为轻度,元素生态风险高低顺序依次为Cd>Hg>Co>Pb>Ni>Cu>Cr>Zn。稀土元素整体表现为轻稀土元素富集,重稀土元素相对亏损的特征,Eu呈中等负异常,无明显Ce异常。轻重稀土元素之间分异显著,轻稀土元素内部分异明显,重稀土元素内部分异不明显。沉积岩源岩及矿物组成对稀土元素的组成起到了控制作用,化学风化对其影响较小。Co、Ni、Cu、Zn主要受矿物自然风化等自然源的影响,Cr、Pb、Cd、Hg主要受工业、农业等人为源的影响;稀土元素主要来源于自身水土侵蚀。

The surface sediments from Xining Section of Shatangchuan River in Qinghai Province were selected as the research object to analyze the pollution degree,potential ecological risks and material sources of eight heavy metals such as Cr,as well as the composition,distribution characteristics and material sources of rare-earth element.The results showed that heavy metals showed mild to moderate pollution,and the pollution load was mild.The order of high and low ecological risk of elements was Cd>Hg>Co>Pb>Ni>Cu>Cr>Zn.Rare-earth elements showed the characteristics of enrichment of light rare-earth elements and relative loss of heavy rare-earth elements,with moderate negative Eu anomalies and no obvious Ce anomalies.The difference between light and heavy rare-earth elements is obvious.The difference between light rare-earth elements is obvious,and the difference between heavy rare-earth elements is not obvious.The source rock and mineral composition of sedimentary rocks control the composition of REE,but chemical weathering has little influence on it.Co,Ni,Cu and Zn are mainly affected by natural sources such as mineral weathering,while Cr,Pb,Cd and Hg are mainly affected by human sources such as industry and agriculture.REE mainly comes from their own soil erosion.