Econ. Environ. Geol. 2014; 47(1): 61-69

Published online February 28, 2014

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Changes of the Oxidation/Reduction Potential of Groundwater by the Biogeochemical Activity of Indigenous Bacteria

Seung Yeop Lee1*, Yul Roh2 and Jong Tae Jeong1

1Korea Atomic Energy Research Institute, Daedeok-daero, Yuseong-gu, Daejeon
2Faculty of Earth Systems and Environmental Sciences, Chonnam National University

Correspondence to : seungylee@kaeri.re.kr

Received: November 4, 2013; Revised: December 29, 2013; Accepted: February 3, 2014

Abstract

  As we are trying to in-situ treat (purify or immobilize) heavy metals or radionuclides in groundwater, one of the geochemical factors to be necessarily considered is the value of oxidation/reduction potential (ORP) of the groundwater. A biogeochemical impact on the characteristic ORP change of groundwater taken from the KAERI underground was observed as a function of time by adding electron-donor (lactate), electron-acceptor (sulfate), and indigenous bacteria in a laboratory condition. There was a slight increase of Eh (slow oxidation) of the pure groundwater with time under a N2-filled glove-box. However, most of groundwaters that contained lactate, sulfate or bacteria showed Eh decrease (reduction) characteristics. In particular, when ‘Baculatum’, a local indigenous sulfate- reducing bacterium, was injected into the KAERI groundwater, it turned to become a highly-reduced one having a decreased Eh to around -500 mV. Although the sulfate-reducing bacterium thus has much greater ability to reduce groundwater than other metal-reducing bacteria, it surely necessitated some dissolved ferrous-sulfate and finally generated sulfide minerals (e.g., mackinawite), which made a prediction for subsequent reactions difficult. As a result, the ORP of groundwater was largely affected even by a slight injection of nutrient without bacteria, indicating that oxidation state, solubility and sorption characteristics of dissolved contaminants, which are affected by the ORP, could be changed and controlled through in-situ biostimulation method.

Keywords groundwater, oxidation/reduction potential, metal-reducing bacteria, mackinawite, biostimulation method

Article

Econ. Environ. Geol. 2014; 47(1): 61-69

Published online February 28, 2014

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Changes of the Oxidation/Reduction Potential of Groundwater by the Biogeochemical Activity of Indigenous Bacteria

Seung Yeop Lee1*, Yul Roh2 and Jong Tae Jeong1

1Korea Atomic Energy Research Institute, Daedeok-daero, Yuseong-gu, Daejeon
2Faculty of Earth Systems and Environmental Sciences, Chonnam National University

Correspondence to:seungylee@kaeri.re.kr

Received: November 4, 2013; Revised: December 29, 2013; Accepted: February 3, 2014

Abstract

  As we are trying to in-situ treat (purify or immobilize) heavy metals or radionuclides in groundwater, one of the geochemical factors to be necessarily considered is the value of oxidation/reduction potential (ORP) of the groundwater. A biogeochemical impact on the characteristic ORP change of groundwater taken from the KAERI underground was observed as a function of time by adding electron-donor (lactate), electron-acceptor (sulfate), and indigenous bacteria in a laboratory condition. There was a slight increase of Eh (slow oxidation) of the pure groundwater with time under a N2-filled glove-box. However, most of groundwaters that contained lactate, sulfate or bacteria showed Eh decrease (reduction) characteristics. In particular, when ‘Baculatum’, a local indigenous sulfate- reducing bacterium, was injected into the KAERI groundwater, it turned to become a highly-reduced one having a decreased Eh to around -500 mV. Although the sulfate-reducing bacterium thus has much greater ability to reduce groundwater than other metal-reducing bacteria, it surely necessitated some dissolved ferrous-sulfate and finally generated sulfide minerals (e.g., mackinawite), which made a prediction for subsequent reactions difficult. As a result, the ORP of groundwater was largely affected even by a slight injection of nutrient without bacteria, indicating that oxidation state, solubility and sorption characteristics of dissolved contaminants, which are affected by the ORP, could be changed and controlled through in-situ biostimulation method.

Keywords groundwater, oxidation/reduction potential, metal-reducing bacteria, mackinawite, biostimulation method

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