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Chemical Reactivity Probes for Assessing Abiotic Natural Attenuation by Reducing Iron Minerals

机译：通过减少铁矿物质评估非生物自然衰减的化学反应探针

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Increasing recognition that abiotic natural attenuation (NA) of chlorinated solvents can be important has created demand for improved methods to characterize the redox properties of the aquifer materials that are responsible for abiotic NA. This study explores one promising approach: using chemical reactivity probes (CRPs) to characterize the thermodynamic and kinetic aspects of contaminant reduction by reducing iron minerals. Assays of thermodynamic CRPs were developed to determine the reduction potentials (E_(CRP)) of suspended minerals by spectrophotometric determination of equilibrium CRP speciation and calculations using the Nernst equation. E_(CRP) varied as expected with mineral type, mineral loading, and Fe(Ⅱ) concentration. Comparison of E_(CRP) with reduction potentials measured potenttometrically using a Pt electrode (E_(Pt)) showed that E_(CRP) was 100-150 mV more negative than E_(Pt). When E_(Pt) was measured with small additions of CRPs, the systematic difference between E_(Pt) and E_(CRP) was eliminated, suggesting that these CRPs are effective mediators of electron transfer between mineral and electrode surfaces. Model contaminants (4-chloronitrobenzene, 2-chloroacetophe- none, and carbon tetrachloride) were used as kinetic CRPs. The reduction rate constants of kinetic CRPs correlated well with the E_(CRP) for mineral suspensions. Using the rate constants compiled from literature for contaminants and relative mineral reduction potentials based on E_(CRP) measurements, qualitatively consistent trends were obtained, suggesting that CRP-based assays may be useful for estimating abiotic NA rates of contaminants in groundwater.
机译：人们日益认识到，氯化溶剂的非生物自然衰减（NA）可能很重要，因此，人们需要改进方法来表征负责非生物NA的含水层材料的氧化还原特性。这项研究探索了一种有前途的方法：使用化学反应探针（CRP）来表征通过还原铁矿物质而减少污染物的热力学和动力学方面。通过分光光度法测定平衡CRP形态并使用能斯特方程进行计算，开发了热力学CRP的测定方法，以确定悬浮矿物的还原电位（E_（CRP））。 E_（CRP）随矿物类型，矿物含量和Fe（Ⅱ）浓度的变化而变化。将E_（CRP）与使用Pt电极（E_（Pt））电位测量的还原电位进行比较，发现E_（CRP）的负电性比E_（Pt）高100-150 mV。在少量添加CRP的情况下测量E_（Pt）时，消除了E_（Pt）和E_（CRP）之间的系统差异，表明这些CRP是矿物和电极表面之间电子转移的有效介质。模型污染物（4-氯硝基苯，2-氯乙酮和四氯化碳）用作动力学CRP。动力学CRP的还原速率常数与矿物悬浮液的E_（CRP）密切相关。使用从文献中收集的污染物常数速率常数和基于E_（CRP）测量的相对矿物质还原潜力，获得了定性一致的趋势，这表明基于CRP的测定法可能对估算地下水中污染物的非生物NA速率有用。

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  • 来源
    《Environmental Science & Technology》 |2016年第4期|1868-1876|共9页
  • 作者

    Dimin Fan; Miranda J. Bradley; Adrian W. Hinkle; Richard L. Johnson; Paul G. Tratnyek;

  • 作者单位

    Institute of Environmental Health Oregon Health & Science University 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States,U.S. Environmental Protection Agency, Office of Superfund Remediation and Technology Innovation, Arlington, Virginia 22202, United States;

    Institute of Environmental Health Oregon Health & Science University 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States;

    Institute of Environmental Health Oregon Health & Science University 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States;

    Institute of Environmental Health Oregon Health & Science University 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States;

    Institute of Environmental Health Oregon Health & Science University 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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