Methods for collection of dissolved sulfate and sulfide and analysis of their sulfur isotopic composition
Methods for collection of dissolved sulfate and sulfide and analysis of their sulfur isotopic composition
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溶解硫酸盐和硫化物的收集方法及其硫同位素组成分析
DOI：
10.3133/ofr97234
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Coplen
中科院分区：
文献类型：
--
作者：
R. Carmody;N. Plummer;E. Busenberg;T. Coplen
地下水和地表水中溶解的硫酸盐和硫化物的硫同位素分析的代表性样品必须用不引起硫同位素分馏的方法收集。这份报告介绍了收集溶解的硫酸盐和硫化物的技术，这些技术对硫同位素进行了最小程度的分馏。直接沉淀法采集的样品没有明显的同位素分馏现象。描述了使用阴离子交换树脂从稀释的地下水和地表水中收集和制备未分级硫酸盐样品的程序。氮气提法采集的溶解硫化物样品相对于直接沉淀法采集的样品通常是分级的(每磨-0.2至-0.5)。相对于直接沉淀法采集的样品，氮气提法采集的Ag2S的同位素组成比直接沉淀法采集的样品富集32S，但随着氮气提时间的延长，S样品中Ag2S的同位素组成变得更加丰富，接近直接沉降值。讨论了将这些分馏降至最低的建议。对从溶解的硫化物和硫酸盐样品中沉淀、称量、提取和分析二氧化硫(SO2)的实验室技术进行了改进。实施这些改进的程序可对各种类型的样品进行可靠的硫同位素分析。
Representative samples for sulfur isotopic analysis of sulfate and sulfide dissolved in ground and surface waters must be collected by methods that do not cause fractionation of the sulfur isotopes. This report presents techniques for collection of dissolved sulfate and sulfide which impose minimal fractionation of the sulfur isotopes. Samples collected by direct precipitation of the dissolved sulfur species show no apparent isotopic fractionation. Procedures are described for collection and preparation of unfractionated sulfate samples from dilute ground and surface waters using anion exchange resin. Dissolved sulfide samples collected by nitrogen stripping are typically fractionated (-0.2 to -0.5 per mill) relative to samples collected by direct precipitation. The isotopic composition of Ag2S collected by nitrogen stripping is enriched in 32S relative to the samples collected by direct precipitation but becomes richer in ^S with duration of nitrogen stripping, approaching the direct precipitation value. Recommendations to minimize these fractionations are discussed. Improvements to laboratory techniques for precipitating, weighing, extracting, and analyzing sulfur dioxide (SO2) from the dissolved sulfide and sulfate samples are presented. Implementation of these improved procedures yields reliable sulfur isotopic analyses on a wide variety of sample types.