• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1999.04a
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• pp.149-156
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• 1999

In the United States (U.S.), the monitored natural attenuation (MNA) approach has been used as an alternative remedial option for organic and inorganic compounds retained in soil and dissolved in groundwater. The U.S. Environmental Protection Agency (EPA) defines the MNA as“in-situ naturally-occurring processes include biodegradation, diffusion, dilution, sorption, volatilization, and/or chemical and biochemical stabilization of contaminants and reduce contaminant toxicity, mobility or volume to the levels that are protective of human health and the environment”. The Department of Soil Environment. National Institute Environmental Research (NIER) is in the process for demonstrating the MNA approach as a potential remedial option for the BTEX contaminated site in Uiwang City. The project is charactering the research site in terms of the nature and extend of contamination, biological degradation rate, and geochemical and hydrological properties. The microbial-degradation rate and effectiveness of nutrient and redox supplements will be determined through laboratory batch and column tests. The geochemical process will be monitored for determining the concentration changes of chemical species involved in the electron transfer processes that include methanogenesis, sulfate and iron reduction, denitrification, and aerobic respiration. Through field works, critical soil and hydrogeologic parameters will be acquired to simulate the effects of dispersion, advection, sorption, and biodegradation on the fate and transport of the dissolved-phase BTEX plume using Bioplume III model. The objectives of this multi-years research project are (1) to evaluate the MNA approach using the BTEX contaminated site in Uiwang City, (2) to establish a standard protocol for future application of the approach, (3) to investigate applicability of the passive approach as a secondary treatment remedy after active treatments. In this presentation, the overall picture and philosophy behind the MNA approach will be reviewed. Detailed discussions of the site characterization/monitoring plans and risk-based decision-making processes for the demonstration site will be included.

• Journal of Soil and Groundwater Environment
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• v.24 no.4
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• pp.1-10
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• 2019

Recently, groundwater contamination by mixed occurrence of arsenic (As) and nitrate ($NO_3{^-}$) has been a serious environmental issue all around world. In this study, we investigated the microbial As(III) oxidation characteristic under denitrification process to examine the feasibility of the microbial consortia in wetland sediment to simultaneously treat these two contaminants. The detail objectives of this study were to investigate the effects of $NO_3{^-}$ on the oxidation of As(III) in anaerobic environments and observe the microbial community change during the As oxidation under denitrification process. Results showed that the As(III) was completely and simultaneously oxidized to As(V) under denitrification process, however, it occurred to a much less extent in the absence of sediment or $NO_3{^-}$. In addition, the significant increase of As(III) oxidation rate in the presence of $NO_3{^-}$ suggested the potential of As oxidation under denitrification by indigenous microorganisms in wetland sediment. Genera Pseudogulbenkiania, and Flavisolibacter were identified as predominant microbial species driving the redox process. Conclusively, this study can provide useful information on As(III) oxidation under denitrifying environment and contribute to develop an effective technology for simultaneous removal of As(III) and $NO_3{^-}$ in groundwater.

• The Plant Pathology Journal
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• v.35 no.4
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• pp.313-320
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• 2019

Rye was used here to dissect molecular mechanisms of resistance to Fusarium head blight (FHB) and to go deeper with our understanding of that process in cereals. F. culmorum-damaged kernels of two lines different in their potential of resistance to FHB were analyzed using two-dimensional gel electrophoresis and mass spectrometry to identify resistance markers. The proteome profiling was accompanied by measurements of ${\alpha}-$ and ${\beta}-amylase$ activities and mycotoxin content. The proteomic studies indicated a total of 18 spots with clear differences in protein abundance between the more resistant and more susceptible rye lines after infection. Eight proteins were involved in carbohydrate metabolism of which six proteins showed a significantly higher abundance in the resistant line. The other proteins recognized here were involved in stress response and redox homeostasis. Three remaining proteins were associated with protease inhibition/resistance and lignin biosynthesis, revealing higher accumulation levels in the susceptible rye line. After inoculation, the activities of ${\alpha}-$ and ${\beta}-amylases$, higher in the susceptible line, were probably responsible for a higher level of starch decomposition after infection and a higher susceptibility to FHB. The presented results could be a good reference for further research to improve crop resistance to FHB.

• Journal of Environmental Science International
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• v.28 no.5
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• pp.511-520
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• 2019

This study was investigated to improve the phosphorus release and water quality by transformation of sedimentary P fraction for application of $CaO_2$. For the experiment, 0.5% (w/w) of $CaO_2$ was homogenized in the sediment and incubated with the control for 20 days. The analytical results showed that pH increased with $CaO_2$ and redox potential (ORP) was improved in the sediment of the reactor. The growth rate of chlorophyll-a was lower in the $CaO_2$ reactor and Dissolved Oxygen (DO) of overlying water maintained higher than that of the control. Total phosphorus (T-P) concentration in the overlying water increased from the initial concentration to 0.304mg/L in the control at 20 days. The reactor of $CaO_2$ was lowered by 29.3%. Ex-P, Fe-P and Ca-P in sediment P fraction were increased with the $CaO_2$. The formation of bound Fe-P and Ca-P in the sediments seemed to control the release of P by removing the Soluble Reactive Phosphorus (SRP) presented in the pore water. From the result, this indicated that the reduction of P release from the sediments seems to be effective in suppressing the eutrophication of P and improving the oxygen condition in the water quality with the application of $CaO_2$.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.67-72
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• 2021

BACKGROUND: Biological iron redox transformation alters iron minerals, which may act as effective adsorbents for arsenate [As(V)] in the environments. In the viewpoint of alleviating arsenate, microbial Fe(III) reduction was sought under high concentration of As(V). In this study, Fe(III)-reducing bacteria were isolated from the wild plant rhizosphere soils collected at abandoned mine areas, which showed tolerance to high concentration of As(V), in pursuit of potential agents for As(V) bioremediation. METHODS AND RESULTS: Bacterial isolation was performed by a series of enrichment, transfer, and dilutions. Among the isolated strains, two strains (JSAR-1 and JSAR-3) with abilities of tolerance to 10 mM As(V) and Fe(III) reduction were selected. Phylogenetic analysis using 16S rRNA genesequences indicated the closest members of Pseudomonas stutzeri DSM 5190 and Paenibacillus selenii W126, respectively for JSAR-1 and JSAR-3. Ferric and ferrous iron concentrations were measured by ferrozine assay, and arsenic concentration was analyzed by ICP-AES, suggesting inability of As(V) reduction whereas ability of Fe(III) reduction. CONCLUSION: Fe(III)-reducing bacteria isolated from the enrichments with arsenate and ferric iron were found to be resistant to a high concentration of As(III) at 10 mM. We suppose that those kinds of microorganisms may suggest good application potentials for As(V) bioremediation, since the bacteria can transform Fe while surviving under As-contaminated environments. The isolated Fe(III)-reducing bacterial strains could contribute to transformations of iron minerals which may act as effective adsorbents for arsenate, and therefore contribute to As(V) immobilization

• Journal of Sensor Science and Technology
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• v.30 no.4
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• pp.229-235
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• 2021

This study presents a simple approach for the assembly of a free-standing conductive electronic nanofilm of single-walled carbon nanotubes (SWNTs) suitable for enzymatic electrochemical biosensors. A large-scale SWNT electronic film was successfully produced by the dialysis of p-Terphenyl-4,4''-dithiol (TPDT)-treated SWNTs. Furthermore, Horseradish peroxidase (HRP) was immobilized on the TPDT-SWNT electronic film, and the enzymatic detection of hydrogen peroxide (H₂O₂) was demonstrated without mediators. The detection of H₂O₂ in the negative potential range (-0.4 V vs. Ag/AgCl) was achieved by direct electron transfer of heme-based enzymes that were immobilized on the TPDT-SWNT electronic film. The SWNT-based biosensor exhibited a wide detection range of H₂O₂ from 10 µM to 10 mM. The HRP-doped SWNT electronic film achieved a high sensitivity of 342 ㎛A/mM·cm² and excellent selectivity against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, and acetaminophen.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.497-503
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• 2022

Spinel ferrites (Ni_xFe_3-xO₄; x = 0.25, 0.5, 0.75 and 1.0) have been prepared at 550℃ by egg white auto-combustion route using egg white at 550℃ and characterized by physicochemical (TGA, IR, XRD, and SEM) and electrochemical (CV and Tafel polarization) techniques. The presence of characteristic vibration peaks in FT-IR and reflection planes in XRD spectra confirmed the formation of spinel ferrites. The prepared oxides were transformed into oxide film on glassy carbon electrodes by coating oxide powder ink using the nafion solution and investigated their electrocatalytic performance for OER in an alkaline solution. The cyclic voltammograms of the oxide electrode did not show any redox peaks in oxygen overpotential regions. The iR-free Tafel polarization curves exhibited two Tafel slopes (b₁ = 59-90 mV decade^-1 and b₂ = 92-124 mV decade^-1) in lower and higher over potential regions, respectively. Ni-substitution in oxide matrix significantly improved the electrocatalytic activity for oxygen evolution reaction. Based on the current density for OER, the 0.75 mol Ni-substituted oxide electrode was found to be the most active electrode among the prepared oxides and showed the highest value of apparent current density (~9 mA cm^-2 at 0.85 V) and lowest Tafel slope (59 mV decade^-1). The OER on oxide electrodes occurred via the formation of chemisorbed intermediate on the active sites of the oxide electrode and follow the second-order mechanism.

• Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.24-34
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• 2023

Reactive oxygen species (ROS) at high concentrations induce oxidative stress, an imbalanced redox state that is a prevalent cause of neurodegenerative disorders. This study aimed to investigate the protective effect of Capsosiphon fulvescens (CF) extract on oxidative stress-induced impairment of cognitive function in models of neurodegenerative diseases. CF was extracted with subcritical water and several solvents and H₂O₂ (0.25 mM) or aluminum chloride (AlCl₃; 25 µM) as an inducer of ROS was treated in PC12 neuronal cells and zebrafish larvae. All statistical analyses were performed using one-way analysis of variance and Dunnett's test using GraphPad Prism. H₂O₂ and AlCl₃ were found to significantly induce ROS production in PC12 neuronal cells and zebrafish larvae. In addition, they strongly affected intracellular Ca²⁺ levels, antioxidant enzyme activity, brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) signaling, acetylcholinesterase (AChE) activity, and hallmarks of Alzheimer's disease. However, treatment of H₂O₂-induced PC12 cells or AlCl₃-induced zebrafish larvae with CF subcritical water extract at 90℃ and CF water extract effectively regulated excessive ROS production, intracellular Ca²⁺ levels, and mRNA expression of superoxide dismutase, glutathione peroxide, glycogen synthase kinase-3 beta, β-amyloid, tau, AChE, BDNF, and TrkB. Our study suggested that CF extracts can be a potential source of nutraceuticals that can improve the impairment of cognitive function and synaptic plasticity by regulating ROS generation in neurodegenerative diseases.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.4
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• pp.484-489
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• 2010

The cultivation of green manure crops plays an important role in soil quality and sustainability of agricultural system. However, the incorporation of green manure crops may be of concern because it can lead to strongly reducing conditions in the submerged soil. This study was conducted to evaluate the effects of rice husk carbon on rice (Oryza sativa L.) cultivation using green manure mixtures (hairy vetch + rye) in rice paddy. Field experiments were conducted in rice paddy soil (Shinheung series, fine loamy, mixed, nonacid, mesic family of Aeric Fluventic Haplaquepts) at the National Institute of Crop Science (NICS), Korea from October 2007 to October 2008. The experiments consisted of three treatments: application or no application of carbonized rice husk, and conventional fertilization. These treatments were subdivided into whole incorporation and aboveground removal of green manure mixtures. The redox potential (Eh) was higher upon application of the carbonized rice husk when compared to no application at 8 and 37 days after transplanting (DAT). The ammonium-N ($NH_4$-N) in soil was highest upon the application of carbonized rice husk + whole green manure incorporation at 17 and 49 DAT. Plant height and tiller number of rice were similar to the $NH_4$-N concentration in soil. Rice yields of application and no application of carbonized rice husk treatment were not significant. However, application of carbonized rice husk improved the soil physical properties such as bulk density and porosity after rice harvest. Therefore, the results of this study suggest that carbonized rice husk could be used as soil amendment for environmentally-friendly rice production under a green manure mixture-rice cropping system.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.3
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• pp.207-213
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• 2009

This experiment was performed to understand the relationship between uptake of Fe and Mn by plants, red pepper and tomato, and soil physico-chemical properties under different soil conditions at an environmentally controlled chamber in NAAS(National Academy of Agricultural Science) in 2008. After the dipping for 3 days, four treatments, dipping, dipping+aeration, drainage, drainage+aeration, were set up to investigate the changes in soil redox potential and moisture content. Drainage+aeration changed soil to the oxidation condition from 72 hrs of treatment, and soil moisture content was immediately reduced after treatment. Uptake of Fe and Mn of red pepper was investigated with two treatments, soil only and the mixed[soil(50%) : bed soil(35%) : bark(15%)]. Red pepper leaves taken at 30 days after treatment absorbed excessively Mn from the treatment of soil only and the mixed, and thus uptake of iron was strongly reduced. Also, uptake pattern of Fe and Mn of tomato was examined with four treatment, soil only, soil(50%) + rice straw(50%), soil(50%) + compost(50%) and soil + aeration. Contents of Fe and Mn in tomato leaves was measured at 60 days after treatment. Fe content was the greatest in soil(50%) + compost(50%) whereas Mn content was the highest in soil only. As a result of this experiment, plant growth was stronger influenced by soil moisture content than redox potential or porosity, and the oxidation status of soil was likely to promote that plant predominantly absorbed Mn from soil and thus resulted in Fe deficiency.