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| Titel |
Degradation of Perchloroethene by zero-valent iron evaluated by carbon isotope fractionation |
| VerfasserIn |
Simon Leitner, Andrea Watzinger, Thomas G. Reichenauer |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095936
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| Publikation (Nr.) |
 EGU/EGU2014-11414.pdf |
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| Zusammenfassung |
| Perchloroethene (PCE) is a widely spread groundwater contaminant in formally used
industrial sites. Zero valent iron (ZVI) is used for in situ chemical reduction (ISCR) of PCE
contaminants in the groundwater. A key factor in the application of in situ remediation
technologies is a proper monitoring of contaminant reduction. The measurement of
the stable isotope ratio is a promising method that is already used for quantifying
microbial degradation of chlorinated contaminants. The carbon isotope ratio of PCE,
measured by – isotope ratio mass spectrometry coupled to a gas chromatograph via a
combustion interface (GC-C-IRMS), increases during degradation of PCE and can be
directly related to the degree of degradation. It can be used to directly quantify
chemical degradation and thus serves as a useful monitoring tool for groundwater
remediation.
An experiment to determine the carbon isotopic fractionation factor was performed as a
lab experiment using Nanofer Star (NANOIRON). Two different PCE concentrations (c1:
220mgL-1, c2: 110mgL-1) mixed with 0.5 g of ZVI were sealed under deoxygenated
conditions in 250 ml glas bottles locked with mininert caps. The bottles were incubated on a
shaker for 865 h. Samples were taken weekly to measure the change in the carbon isotopic
ratio of PCE as well as its concentration.
Results showed a strong increase in the carbon isotope ratio (δ-value) of PCE (start:
-27o end: -4), which indicates a significant dechlorination process of PCE. Beside PCE
also one degradation product (Trichloroethylene – TCE) was measured. TCE was further
dechlorinated as indicated by the δ-value change of TCE from -26oto -4oȦn
unexpected intermediate value of -45ofor TCE was observed in the experiment. This
fluctuation could be induced by the time depending concentration due to degradation and
conversation processes. Furthermore, it seems that the progress of the δ-value is affected by
the starting concentration of PCE (δ-value of c1 < c2) as there is a higher ratio of PCE to
ZVI. |
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