Reliable Extraction of Seawater Nd and Hf Isotope Compositions from Fe-Mn Oxyhydroxide Fraction of Marine Sediments in the Arctic Ocean
10.19756/j.issn.0253-3820.241335
- VernacularTitle:北极海洋沉积物中铁-锰氧化物相钕和铪同位素提取方法研究
- Author:
Ying ZHANG
1
;
Lin-Sen DONG
;
Hong-Min WANG
;
Xiao-Jing WANG
;
Lian-Hua HE
;
Yan-Guang LIU
;
Ji-Hua LIU
Author Information
1. 自然资源部第一海洋研究所,青岛 266061;自然资源部海洋地质与成矿作用重点实验室,青岛 266061;青岛海洋科技中心海洋地质过程与环境功能实验室,青岛 266237
- Keywords:
Marine sediment;
Fe-Mn oxyhydroxide;
Nd isotopes;
Hf isotopes;
Extraction;
Arctic
- From:
Chinese Journal of Analytical Chemistry
2025;53(8):1380-1390
- CountryChina
- Language:Chinese
-
Abstract:
Combined seawater Hf and Nd isotope compositions have been applied as reliable tracers of water mass mixing and weathering input changes.The establishment of standardized synchronous extraction methods for Fe-Mn oxyhydroxide in sediments,which serve as effective carriers for isotopic signals of ancient seawater,is a prerequisite and key for paleoceanography research.The research material of this study was the surface sediments of the Western Arctic Ocean obtained from China's 7th Arctic Scientific Expedition,and a reliable simultaneous Nd-Hf isotope extraction method in Fe-Mn oxyhydroxide fraction was established through systematic optimization of pretreatment procedures and key extraction parameters.This research focused on analyzing the effects of pretreatment(Milli-Q water pre-wash)and key extraction parameters(leaching time,solution/solid ratios,concentration of EDTA-2Na,and concentration of mixed solution of hydroxyamine hydrochloride(HH)and acetic acid(HAc))on element extraction efficiency and isotopic composition.The experimental results indicated that the Milli-Q water pre-wash was not necessary,Fe-Mn oxyhydroxide extraction could be directly performed.Nd extraction amount in Fe-Mn oxyhydroxide fraction was not sensitive to changes in extraction conditions,while the Hf extraction amount was significantly affected by leaching time,solution/solid ratios and concentration of EDTA-2Na.The optimal conditions for synchronously extracting Nd-Hf isotopes were as follows:adding 20 mL of a mixed solution of 0.005 mol/L HH+1.5%HAc+0.03 mol/L EDTA-2Na per gram of sample,and reaction at room temperature for 3 h under shaking.Through systematic verification of 87Sr/86Sr ratio,εNd value,εHf value,Al/Nd ratio and Al/Hf ratio,it was confirmed that this method could effectively avoid interferences from residual components and accurately obtain Nd-Hf isotope signals of ancient seawater preserved in sediments.The standardized method established in this work provided reliable technical support for reconstructing water mass mixing between the Arctic,North Atlantic,and North Pacific Oceans and riverine input histories.It also provided important reference for the extraction methods of Nd and Hf isotopes from marine sources in sediments from other sea areas around the world.
