大同盆地沉积物REE分布特征及其对碘富集的指示

发布时间：2018-07-21 18:40

【摘要】：大同盆地是典型的干旱-半干旱内陆盆地,盆地中部地下水碘含量异常,对当地饮用水安全造成了严重威胁.对盆地高碘地下水分布区沉积物组成及稀土元素(REE)进行了地球化学研究,结果表明,地下水系统呈弱碱性(pH值为7.18~9.64)的偏还原环境,沉积物多为Ce正常或轻微负异常及Eu负异常;沉积物中碘含量为0~1.78×10~(-6);ΣREE含量较高,ΣLREE/ΣHREE比值为2.79~4.14,即富集轻稀土元素(LREE)而亏损重稀土元素(HREE).ΣREE与碘含量呈负相关关系,虽然铁氧化物/氢氧化物矿物的还原性溶解可导致二者的释放,但由于沉积物有机质产生的低结晶矿物对碘的强吸附性,使沉积物中碘含量较高;弱碱性环境中REE的再吸附过程会导致沉积物中富集LREE;沉积物中碘含量与氧化还原敏感组分TOC、U、V及[Eu]N的关系也表明,地下水系统的氧化还原条件及有机质含量是影响碘富集的重要因素.
[Abstract]:Datong basin is a typical arid-semi-arid inland basin. The anomaly of iodine content in groundwater in the central part of the basin poses a serious threat to the safety of local drinking water. The composition of sediments and rare earth elements (REE) in the area of high iodine groundwater distribution in the basin are studied. The results show that the groundwater system shows a weak alkaline (pH 7.189.64) partial reduction environment, and the sediments are mostly ce normal or slight negative anomalies and EU negative anomalies. The iodine content in sediment is 0 ~ 1.78 脳 10 ~ (-6), 危 REE content is high, 危 LREE / 危 hree ratio is 2.79 ~ 4.14, that is, enriched light rare earth element (LREE) and depleted heavy rare earth element (hree). 危 REE is negatively correlated with iodine content, although the reductive dissolution of iron oxide / hydroxide mineral may lead to their release. However, due to the strong adsorption of iodine by the low crystalline minerals produced by organic matter in sediments, the iodine content in sediments is higher. The readsorption process of REE in weakly alkaline environment will lead to the enrichment of LREE in sediments, and the relationship between iodine content in sediments and the sensitive components of redox, TOCX UV and [EU] N, also indicates that the readsorption process of REE in sediments may lead to the enrichment of LREE in sediments. The redox conditions and organic matter content of groundwater system are important factors affecting iodine enrichment.
【作者单位】：中国地质大学环境学院;中国地质大学生物地质与环境地质国家重点实验室;
【基金】：国家自然科学基金项目(No.41502230)
【分类号】：P641.3

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