Degradation of Metal-Nitrilotriacetate Complexes by Chelatobacter heintzii

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• 作者：Harvey Bolton ; Jr. ; Don C. Girvin ; Andrew E. Plymale ; Scott D. Harvey ; and Darla J. Workman
• 刊名：Environmental Science & Technology
• 出版年：1996
• 出版时间：March 1996
• 年：1996
• 卷：30
• 期：3
• 页码：931 - 938
• 全文大小：442K
• 年卷期：v.30,no.3(March 1996)
• ISSN：1520-5851

文摘

Nitrilotriacetic acid (NTA) is a synthetic chelatingagent that can form strong water-soluble complexeswith a wide range of radionuclide and metal ionsand has been used to decontaminate nuclear reactorsand in the processing of nuclear materials. The co-disposal of NTA or other synthetic chelating agentswith radionuclides may result in increased dispersalof radionuclides in soil and subsurface environments.Understanding the influence of aqueous geochemistryon NTA degradation is essential to predict themobility and fate of inorganic contaminant-NTAcomplexes in the subsurface. Chelatobacterheintzii(ATCC 29600) was shown to degrade¹⁴C-labeledNTA to¹⁴CO₂ with first-order kinetics atconcentrationsranging from 0.05 to 5.23 µM (0.01-1 µg of NTAmL^-1). The degradation of variousmetal-NTAcomplexes was investigated under conditions in whichthe NTA was predominantly present as the metal-NTA complex. The order for the rates ofdegradation was HNTA^2- >CoNTA^- = FeOHNTA^-= ZnNTA^- > AlOHNTA^- >CuNTA^- > NiNTA^-,which is not related to the order of metal-NTA stabilityconstants. The metal concentration used was notinhibitory to glucose mineralization, suggesting thattoxicity of the chelated metal was not responsiblefor the differences in the rates of NTA degradation.After degradation of CoNTA^- andNiNTA^-, <3% ofthe Co or Ni was associated with C. heintziicells. Thisindicates that, after degradation of the metal-NTAcomplex, metal ions will be predominantly present inthe aqueous phase. The degradability of the variousmetal-NTA complexes was not related to their thermodynamic stability constants, but was related tothe lability of the various metal-NTA complexes or therelative rates of formation ofHNTA^2-.