Abstract Adsorption plays an important role in the biogeochemical cycling of selenium (Se) in natural environments and Se isotope fractionation during adsorption is a significant but poorly studied part of Se isotope system. This paper examined Se(IV) and Se(VI) adsorption onto four naturally occurring metal oxides (hematite, manganese dioxide (β-MnO2), and α and γ-alumina oxides) and revealed Se isotope fractionation as a function of the absorbents used, Se species adsorbed, exposure time, and pH. The results show that Se(IV)/(VI) adsorption was initially rapid and was accompanied with kinetic isotope fractionations as large as 3‰, but slowed down as adsorption equilibrium was approached, eventually approaching isotopic equilibrium. The Se(IV) adsorption onto the studied metal oxides took at least 12 h to reach adsorption equilibrium, longer than Se(VI) adsorption (

中文翻译：

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Fe、Mn 和 Al 氧化物吸附过程中硒同位素分馏

摘要 吸附在自然环境中硒 (Se) 的生物地球化学循环中起着重要作用，吸附过程中的硒同位素分馏是硒同位素系统中一个重要但研究较少的部分。本文研究了 Se(IV) 和 Se(VI) 在四种天然存在的金属氧化物（赤铁矿、二氧化锰 (β-MnO2) 以及 α 和 γ-氧化铝）上的吸附，并揭示了 Se 同位素分馏作为所用吸收剂的函数、吸附的Se种类、暴露时间和pH值。结果表明，Se(IV)/(VI)吸附最初是快速的，伴随着高达3‰的动力学同位素分馏，但随着接近吸附平衡而减慢，最终接近同位素平衡。Se（IV）吸附到所研究的金属氧化物上至少需要 12 小时才能达到吸附平衡，