晚更新世以来古气候变化对长江中游故道区冲湖积含水层中碘富集的控制作用  

Controlling Mechanism of Paleoclimate Change on Iodine Enrichment in Alluvial Aquifers of Middle Reach of Yangtze River since Late Pleistocene

作　　者：薛伟广 邓娅敏 薛江凯 杜尧 徐雨潇 范瑞宇 Xue Weiguang;Deng Yamin;Xue Jiangkai;Du Yao;Xu Yuxiao;Fan Ruiyu(Key Laboratory of Groundwater Quality and Health of Ministry of Education,Wuhan 430074,China;Institute of Geological Survey,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]地下水质与健康教育部重点实验室,湖北武汉430074 [2]中国地质大学地质调查研究院,湖北武汉430074

出　　处：《地球科学》2024年第10期3749-3760,共12页Earth Science

基　　金：国家自然科学基金国际(地区)合作与交流项目(No.42020104005)。

摘　　要：长江中游故道区冲湖积含水层中存在原生高碘地下水,对区域供水安全构成严重威胁.含水层沉积物中的铁矿物和有机质是碘的主要载体,从宏观地质背景和沉积演化的角度揭示晚更新世以来的气候变化对含水层中碘富集的控制机制是科学认识高碘地下水成因和保障供水安全的前提.选取长江中游故道区的第四纪沉积物作为研究对象,系统分析沉积物地球化学特征,识别含水层沉积物中碘赋存的主要载体,揭示古气候变化驱动的化学风化与沉积过程对含水层碘富集的控制机理.研究结果表明:沉积物中碘的主要赋存形态是铁氧化物结合态(I_(Fe-ox))和有机结合态(I_(org)),而且沉积物的化学风化指数CIA、K/Na比值与I_(Fe-ox)、I_(org)呈显著正相关.无定型铁氧化物(Fe_(ox1))、粘土矿物及有机质是碘赋存的主要载体.晚更新世-全新世以来气候从寒冷干燥转为温暖潮湿,化学风化增强促使更多无定型铁氧化物形成,全新世以后广泛扩张的湖泊导致碘、有机质与铁氧化物在湖相沉积物中共埋藏.古气候变化对长江中游故道区含水层中碘的富集起重要控制作用.The presence of geogenic high iodine groundwater in alluvial aquifers in the middle reach of the Yangtze River poses a serious threat to regional water supply security.Iron minerals and organic matter in aquifer sediments are the main carriers of iodine,and revealing the control mechanism of climate change on iodine enrichment in aquifers since the Late Pleistocene from the perspective of regional-geological background and sedimentary evolution is a prerequisite for scientific understanding of the causes of high iodine groundwater and ensuring water supply security.In this study,Quaternary sediments in the distribution area of high iodine groundwater in the middle reach of the Yangtze River were collected,and sediment geochemistry was systematically characterized to identify the main carriers of iodine enrichment in aquifer sediments and to reveal the controlling mechanisms of iodine enrichment in aquifers by weathering and deposition pocesses driven by paleoclimatic changes.The results show that the main iodine speciation in sediments are iron oxide-bounded(I_(Fe-ox))and organic matter bounded(I_(org)),and the chemical weathering index CIA and K/Na ratio of sediments are significantly positively correlated with I_(Fe-ox)and Iorg.Amorphous iron oxides(Fe_(ox1)),clay minerals and organic matter are the main carriers of iodine.Climate changed from cold and arid to warm and humid since the Late Pleistocene and Holocene,enhanced chemical weathering,which contributed to the formation of more amorphous iron oxides,and the expansion of lakes after the Holocene led to the co-burial of iodine,organic matter and iron oxides in the lacustrine sediments.Paleoclimatic changes play an important role in controlling iodine enrichment in the middle Yangtze River aquifer.

关 键 词：碘 沉积物 铁形态 古气候 化学风化 水文地质学 

分 类 号：P641[天文地球—地质矿产勘探] P595[天文地球—地质学]