High-precision double-spike Cd isotopic measurements of seawater by MC-ICP-MS and its application to seawater affected by hydrothermal vent fluids

作     者：Chuanwei Zhu Yunzhu Wu Hanjie Wen Guanghai Wu Wenrui Song Yuxu Zhang Bo Zhao Chuanwei Zhu;Yunzhu Wu;Hanjie Wen;Guanghai Wu;Wenrui Song;Yuxu Zhang;Bo Zhao

作者机构：State Key Laboratory of Ore Deposit GeochemistryInstitute of GeochemistryChinese Academy of SciencesGuiyang 550081China School of Earth ResourcesChina University of GeosciencesWuhan 430074China School of Earth Sciences and ResourcesChang’An UniversityXi’an 710054China College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Submarine GeosciencesSecond Institute of OceanographyMNRHangzhou 310012China Institute of Land Engineering and TechnologyShaanxi Provincial Land Engineering Construction Group Co.Ltd.Xi’an 710075ShaanxiChina 

出 版 物：《地球化学学报(英文)》 (Acta Geochimica)

年 卷 期：2023年第42卷第5期

页      面：934-942页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the National Natural Science Foundation of China(Grant No.42073010) the Key Research and Development Program of Yunnan Province(Grant No.202103AQ100003) a special fund managed by the State Key Laboratory of Ore Deposit Geochemistry,Chinese Academy of Sciences. 

主　　题：Cd isotope Seawater Plume Hydrothermal system 

摘      要：Cadmium(Cd)isotopes in seawater have been proven as an important geochemical tool for tracing ocean Cd circulation in the modern ocean.In this study,we evaluated a new method to separate Cd(*60 ng)from seawater using Chelex resin(1.0 g)coupled with AG-MP-1M resin.The results show that the Chelex resin is suffi-cient to remove Cd from Na and Mg matrix with Cd recoveries at 98.3±3.5%(2SD,N=6);while AG-MP-1M resin could separate Cd from the residual Na,Mg,and isobaric inferences.The total Cd recoveries of the method are 96.3±1.5%(2SD;N=4)and the salinity of the samples has no significant impacts on Cd recovery.Cd isotope ratios were measured using a Nu PlasmaⅢMC-ICP-MS and^(111)Cd–^(110)Cd double spike technique.By comparing theδ^(114/110)Cd values(0.00±0.06%)of synthetic seawaters doped with Cd isotope standard(NIST-3108;treated by Chelex+AG-MP-1M resin)and the reference value(-0.00%),no variations were observed.We also analyzed the Cd isotope compositions of three deep seawaters from a column at the Southwest Indian Ocean Ridges(SWIR).Theδ^(114/110)Cd values of the col-umn are decreased from 1.05±0.05%at 3200 m to 0.36±0.05%at 2800 m,differing from reportedδ^(114/110)Cd values of deep seawater in other oceans.Considering the spatial distance between the column and active hydrothermal vents in SWIR(-13 km),we propose that such positiveδ^(114/110)Cd values of deep seawater were likely contaminated by vent fluids,which could provide heavy Cd isotope to deep seawaters.This study demon-strates that Cd isotope is more sufficient to distinguish the impact of plumes on deep seawater.