巢湖沉积物稀土元素地球化学特征及环境意义  

GEOCHEMICAL FEATURES OF RARE EARTH ELEMENTS IN SEDIMENTS OF THE CHAOHU LAKE AND ITS ENVIRONMENTAL IMPLICATIONS

作　　者：郭敏[1] 徐利强[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009

出　　处：《海洋地质与第四纪地质》2016年第4期137-144,共8页Marine Geology & Quaternary Geology

基　　金：中国博士后科学基金(2014M550338);中央高校基本科研业务费专项资金(2013bh2x0026);国家自然科学基金(41402148)

摘　　要：以采自西巢湖湖心的CHX沉积柱为研究对象,分析了稀土元素随沉积剖面的变化过程,结果发现样品中总稀土元素的含量为(234.7±17.9)μg/g,略高于地壳平均水平,CHX沉积柱样轻稀土元素明显富集,轻重稀土比值(ΣLREE/ΣHREE)平均为9.7,Eu元素存在一定程度的负异常,Ce为轻微正异常,稀土配分模式为典型的右倾型。整个剖面可划分为两个沉积单元,30cm深度以下的稀土元素与黏土含量正相关,粒度是主控因素,反映了自然因素对稀土含量的控制,在30cm以上,稀土元素含量快速增加,ΣLREE/ΣHREE值也明显较高,其控制因素变得复杂。结合210Pb测年,发现稀土元素含量的快速增加发生在最近约200年,这可能反映了近现代人类活动会对稀土元素在沉积物中的含量和分布产生影响,而最表层样品中稀土元素一定程度的下降,可能与我国能源结构的优化和渔业捕捞量的逐渐增加有关。A sediment core（named CHX hereafter）was collected from the center of the western Chaohu Lake.The concentrations of rear earth elements（REEs）in different layers of the core were analyzed using ICP-MS.The results show that the mean concentration of REE in the samples is（234.7±17.9）μg/g（n=71）,slightly greater than that of the average crust.It is also found that the light REE concentrations in the sediments are evidently higher than the heavy REE,and the ratio of light REE to heavy REE（ΣLREE/ΣHREE）averages 9.7.In addition,the feature of Eu shows obviously negative anomaly,but Ce shows slightly positive anomaly in the core CHX.Chondrite normalized REE distribution pattern of the sediments is characterized by the enrichment of light REE.The lake deposits can be divided into two sedimentary layers.For the sediments below the depth 30 cm,the contents of REE and clay minerals are significantly and positively correlated.It is identified that grain size is the controlling factor for REE distribution,and this reflects the control of natural factors on the REE concentrations.In contrast,REE contents andΣLREE/ΣHREE values in the sediments above 30 cm depth are significantly higher than those below,and the level of REE is no longer controlled by clay concentration.In combination with 210Pb-dating,it is found that the content of REE have been increasing over the last 200 years.This may reflect the increasing impact of modern human activities on the sediments,and the decrease inΣREE in most recent sediments is perhaps caused by optimization of energy structure and dramatic increasing of fishery catches.

关 键 词：稀土元素 湖泊沉积物 210Pb 人类活动 巢湖 

分 类 号：P595[天文地球—地球化学]