Copper Isotope Fractionation during Complexation with Insolubilized Humic Acid

被引:112
作者
Bigalke, Moritz [1 ,2 ]
Weyer, Stefan [3 ]
Wilcke, Wolfgang [2 ]
机构
[1] Johannes Gutenberg Univ Mainz, Inst Geog, Earth Syst Sci Res Ctr, D-55128 Mainz, Germany
[2] Univ Bern, Inst Geog, CH-3012 Bern, Switzerland
[3] Goethe Univ Frankfurt, Inst Geosci, D-60438 Frankfurt, Germany
关键词
NICA-DONNAN MODEL; METAL-ION BINDING; RAY-ABSORPTION SPECTROSCOPY; ORGANIC-MATTER; EXAFS EVIDENCE; SUBSTANCES; ZINC; ADSORPTION; SITES; SOILS;
D O I
10.1021/es1017653
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The bioavailability, mobility, and toxicity of Cu depend on Cu speciation in solution. In natural systems like soils, sediments, lakes, and river waters, organo-Cu complexes are the dominating species. Organo-complexation of Cu may cause a fractionation of stable Cu isotopes. The knowledge of Cu isotope fractionation during sorption on humic acid may help to better understand Cu isotope fractionation in natural environments and thus facilitate the use of Cu stable isotope ratios (delta(65)Cu) as tracer of the fate of Cu in the environment. We therefore studied Cu isotope fractionation during complexation with insolubilized humic acid (IHA) as a surrogate of humic acid in soil organic matter with the help of sorption experiments at pH 2-7. We used NICA-Donnan chemical speciation modeling to describe Cu binding on IHA and to estimate the influence of Cu binding to different functional groups on Cu isotope fractionation. The observed overall Cu isotope fractionation at equilibrium between the solution and IHA was Delta(65)Cu(IHA-solution) = 0.26 +/- 0.11 parts per thousand (2SD). Modeled fractionations of Cu isotopes for low- (LAS) and high-affinity sites (HAS) were identical with Delta(65)Cu(LAS/HAS-solution) = 0.27. pH did not influence Cu isotope fractionation in the investigated pH range.
引用
收藏
页码:5496 / 5502
页数:7
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