Kopinke Frank-Dieter, Georgi Anett, Voskamp Michael, Richnow Hans H
Departments of Environmental Technology, UFZ Centre for Environmental Research, Leipzig-Halle Ltd., Permoserstrasse 15, 04318 Leipzig, Germany.
Environ Sci Technol. 2005 Aug 15;39(16):6052-62. doi: 10.1021/es040096n.
Experimental approaches were developed which permit the measurement of carbon isotope effects during partitioning of organic compounds between water and humic substances. Fractionation factors alpha(sorption) = K(OC)12C/K(OC)13C for carbon isotopomers of benzene (1.00044 +/- 0.00015) and toluene (1.00060 +/- 0.00010) were determined from a 10-step batch experiment. Similar fractionation factors were estimated for benzene (1.00017), 2,4-dimethylphenol (1.00035), and o-xylene (< or = 1.00092) from chromatographic experiments. The latter method is based on chromatographic amplification of the fractionation effect (deltadelta13C) in an HPLC column with humic acid (HA) as the stationary phase. Possible implications of the sorption-based isotope fractionation for assessment of natural attenuation processes in contaminated aquifers are discussed. Depending on the aquifer properties (organic carbon content, heterogeneity) together with the plume source, length, and status (stationary or expanding), scenarios may be constructed where sorption-based isotope fractionation competes significantly with that caused by chemical or microbial degradation processes.
已开发出实验方法，可用于测量有机化合物在水和腐殖质之间分配过程中的碳同位素效应。通过10步批次实验确定了苯（1.00044±0.00015）和甲苯（1.00060±0.00010）碳同位素异构体的分馏因子α（吸附）=K（OC）12C/K（OC）13C。通过色谱实验估计了苯（1.00017）、2,4-二甲基苯酚（1.00035）和邻二甲苯（≤1.00092）的类似分馏因子。后一种方法基于以腐殖酸（HA）为固定相的HPLC柱中分馏效应（δδ13C）的色谱放大。讨论了基于吸附的同位素分馏对评估受污染含水层中自然衰减过程的可能影响。根据含水层特性（有机碳含量、非均质性）以及羽流源、长度和状态（静止或扩展），可以构建一些情景，其中基于吸附的同位素分馏与化学或微生物降解过程引起的分馏有显著竞争。
