不同化学淋滤方法对沉积物碎屑组分中REE和Sr-Nd同位素测试的影响  

The impact of different chemical leaching methods on REE and Sr-Nd isotopes analysis of sediment detrital components

作　　者：赖伟波 李超[1] 马松阳 郭玉龙[1] 岳伟 贺茂勇[4] 万世明[5] 杨守业[1] LAI Weibo;LI Chao;MA Songyang;GUO Yulong;YUE Wei;He Maoyong;WAN Shiming;YANG Shouye(State Key Laboratory of Marine Geology(Tongji University),Shanghai 200092,China;Guangzhou Marine Geological Survey,China Geological Survey,Guangzhou 510760,China;School of Geography,Geomatics&Planning,Jiangsu Normal University,Xuzhou 221116,China;State Key Laboratory of Loess and Quaternary Geology,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710000,China;Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China)

机构地区：[1]同济大学海洋地质国家重点实验室,上海200092 [2]中国地质调查局广州海洋地质调查局,广州510760 [3]江苏师范大学地理测绘与城乡规划学院,徐州221116 [4]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710000 [5]中国科学院海洋研究所海洋地质与环境重点实验室,青岛266071

出　　处：《海洋地质与第四纪地质》2025年第2期203-214,共12页Marine Geology & Quaternary Geology

基　　金：国家重点研发计划项目“亚洲大陆边缘晚新生代风化沉积模式及碳汇效应”(2022YFF0800504);国家自然科学基金项目“根据河流沉积物(234U/238U)计算流域尺度的平均侵蚀速率”(42273057),“晚更新世以来巽他陆架暴露对沉积物输运模式和风化沉积记录的影响”(42076063);上海市自然科学基金项目“基于230Th标准化的南海西南部质量累积速率校正和古生产力重建”(21590712700)。

摘　　要：沉积物是一种成分复杂的混合物,不同地学研究往往需要提取沉积物中不同的化学组分。顺序淋滤是区分沉积物不同组分较为常用的方法,但目前开展的顺序淋滤实验往往只针对单一类型沉积物样品开展探索,其淋滤效果是否也广泛适用其他类型沉积物样品并不清楚。本研究选取了来自长江、黄土高原以及南海的3种不同类型沉积物样品,借鉴目前应用较多的两种顺序淋滤流程以及本文改进的流程共计3种方法对样品进行淋洗,评估不同淋洗方法对样品中碎屑组分REE和Sr-Nd同位素测试的影响。研究证实1.5 mol/L盐酸会过度去除样品中的碳酸盐组分,导致部分主量元素(Mn、Fe和Mg)和REE元素的损失达50%以上,还可能会造成包括黏土矿物在内的部分硅酸盐碎屑组分溶解;酸性较适中的1 mol/L醋酸钠缓冲溶液更利于准确去除沉积物中的碳酸盐组分。非碎屑组分的去除会导致沉积物Sr同位素升高,影响碎屑组分Sr同位素组成的主要是碳酸盐组分。对Nd同位素,非碎屑组分的去除会导致沉积物碎屑组分ɛNd降低1—2个单位,但是Nd的淋失率与碎屑组分ɛNd的变化关系更加复杂,过度的震荡和延长反应时间对不同类型沉积物ɛNd的影响机制仍有待进一步研究。Sediments are complex mixtures,and different geological studies often require the extraction of different chemical components from sediments.Sequential leaching is a commonly used method to differentiate different components of sediments.However,the effectiveness of sequential leaching experiments conducted so far is often explored only for a single type of sediment sample.It is unclear whether the leaching effect is also widely applicable to other types of sediment samples.In this study,three types of sediment samples from the Yangtze River,the Loess Plateau,and the South China Sea were selected.Three methods,including two commonly used sequential leaching procedures and an improved procedure proposed in this study,were applied to leach the samples.The aim was to assess the impact of different leaching methods on the REE and Sr-Nd isotopes analysis of the sediment detrital components.Results show that 1.5 M hydrochloric acid tends to excessively remove carbonate components from the samples,leading to a loss of over 50%of some major elements(Mn,Fe,and Mg)and REE elements.It could also cause the dissolution of some silicate detrital components,including clay minerals.1 M sodium acetate buffer solution with moderate acidity was shown more favorable for accurately removing carbonate components from all sediments.The removal of non-detrital components resulted in an increase of Sr isotopes in all the sediments.The main component influencing the isotopic composition of Sr in detrital components was the carbonate fraction.For Nd isotopes,the removal of non-detrital components led to a decrease inɛNd of sediment detrital components by 1—2 units.However,the relationship between the loss of Nd and the changes in detrital componentɛNd is more complex,and the effects of excessive shaking and prolonged reaction time on theɛNd of different types of sediments still require further investigation.

关 键 词：化学淋洗 非碎屑组分 REE SR-ND同位素 方法比较 

分 类 号：P736[天文地球—海洋地质]