ABSTRACT Selenium and oxygen isotope systematics can be useful tools for tracing sources and fate of Se oxyanions in water. In order to measure δ18O values of selenate, SeO4 2– must first be sequestered from water by precipitation as BaSeO4(s). However, other dissolved oxyanions insoluble with Ba2+ require removal. Dissolved selenate was separated from dissolved selenite, carbonate, phosphate, and arsenate by addition of Ce3+ cations that quantitatively removed these oxyanions by precipitation as insoluble Ce2(SeO3)3(s), Ce2(CO3)3(s), CePO4(s), and CeAsO4(s), respectively. δ18O-selenate (−8.19 ± 0.17 ‰) did not change after four replicates of selenite removal by Ce2(SeO3)3(s) precipitation and Ce3+ removal by cation exchange (−8.20 ± 0.14, −8.32 ± 0.09, −8.17 ± 0.13, and −8.29 ± 0.13 ‰). δ18O-selenate values (−10.86 ± 0.45 ‰) were preserved also when selenate was pre-concentrated on anion exchange resin, quantitatively retrieved by elution, and processed with Ce3+ to remove interfering oxyanions (−10.77 ± 0.07 ‰). The extraction and purification steps developed here successfully isolated dissolved selenate from interfering oxyanions while preserving δ18O-selenate values. This method should be useful for characterizing δ18O-selenate when present with the co-occurring oxyanions above in laboratory experiments and field sites with high Se concentrations, although further research is required for methods to eliminate any co-occurring sulphate.

中文翻译：

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从亚硒酸盐、碳酸盐、磷酸盐和砷酸盐溶液中分离硒酸盐，用于 δ18O-硒酸盐测定

摘要 硒和氧同位素系统学可以成为追踪水中硒氧阴离子的来源和归宿的有用工具。为了测量硒酸盐的 δ18O 值，SeO4 2– 必须首先通过沉淀作为 BaSeO4(s) 从水中隔离。然而，其他不溶于 Ba2+ 的溶解氧阴离子需要去除。通过添加 Ce3+ 阳离子将溶解的硒酸盐与溶解的亚硒酸盐、碳酸盐、磷酸盐和砷酸盐分离，这些阳离子通过沉淀作为不溶性 Ce2(SeO3)3(s)、Ce2(CO3)3(s)、CePO4(s) 定量去除这些氧阴离子, 和 CeAsO4(s)，分别。通过 Ce2(SeO3)3(s) 沉淀去除亚硒酸盐和通过阳离子交换去除 Ce3+（-8.20 ± 0.14、-8.32 ± 0.09、-8.17 ± 0.13）四次重复后，δ18O-硒酸盐 (-8.19 ± 0.17 ‰) 没有变化, 和 -8.29 ± 0.13 ‰)。δ18O-硒酸盐值 (-10.86 ± 0. 当硒酸盐在阴离子交换树脂上预浓缩，通过洗脱定量回收，并用 Ce3+ 处理以去除干扰性氧阴离子 (-10.77 ± 0.07 ‰) 时，也保留了 45 ‰)。此处开发的提取和纯化步骤成功地将溶解的硒酸盐与干扰性氧阴离子分离，同时保留了 δ18O-硒酸盐值。在实验室实验和具有高 Se 浓度的现场现场，当 δ18O-硒酸盐与上述共存的氧阴离子一起存在时，该方法应该有助于表征 δ18O-硒酸盐，尽管需要进一步研究消除任何共存硫酸盐的方法。此处开发的提取和纯化步骤成功地将溶解的硒酸盐与干扰性氧阴离子分离，同时保留了 δ18O-硒酸盐值。在实验室实验和具有高 Se 浓度的现场现场，当 δ18O-硒酸盐与上述共存的氧阴离子一起存在时，该方法应该可用于表征 δ18O-硒酸盐，尽管需要进一步研究消除任何共存硫酸盐的方法。此处开发的提取和纯化步骤成功地将溶解的硒酸盐与干扰性氧阴离子分离，同时保留了 δ18O-硒酸盐值。在实验室实验和具有高 Se 浓度的现场现场，当 δ18O-硒酸盐与上述共存的氧阴离子一起存在时，该方法应该有助于表征 δ18O-硒酸盐，尽管需要进一步研究消除任何共存硫酸盐的方法。