Kim K.,Kunsan National University |
Kim S.-H.,Kunsan National University |
Jeong G.Y.,Andong National University |
Kim R.-H.,Korea Environment Corporation
Journal of Hazardous Materials | Year: 2012
Arsenic (As) concentrations and As-bearing minerals in bedrock and soil, and their relations with groundwater concentrations were investigated in a small agricultural area of Korea. The As concentration of the bedrock shows a wide variation (<0.5-3990. mg/kg) and is well correlated with that in the contacting groundwaters (23-178 μg/L). Soils, the weathering product of bedrock, show the lower and more dispersed As concentrations (8.8-387. mg/kg) than the bedrock. But the soil As concentrations are very high relative to those reported from other areas. The As concentrations in the shallow groundwaters are comparatively low (<20 μg/L) and are independent of the soil concentration. Arsenopyrite is the major As-bearing mineral in the bedrock and its oxidation controls the As levels in deep groundwater. In contrast, As mostly resides in soil as Fe-(hydr)oxide-bound forms. Due to low pH and oxidizing redox condition, the release of As from Fe-(hydr)oxides is largely suppressed, and the shallow groundwater shows low As concentrations generally satisfying the drinking water limit. However, it is suggested that the disturbance of soil geochemical conditions by land use changes would cause a serious As contamination of the shallow groundwaters. © 2011 Elsevier B.V.
Lee H.-J.,Chonnam National University |
Hong M.-K.,Korea Environment Corporation |
Moon S.-H.,Gwangju Institute of Science and Technology
Desalination | Year: 2012
Interests on the polarity reversal have increased to prevent or minimize membrane fouling and scaling during the operation of electromembrane processes. In this study, the influence of the operation conditions on the process efficiency was investigated in the electrodeionization reversal (EDIR) system with an electrodeionization with the polarity reversal. The removal efficiencies of divalent cations (Mg 2+ and Ca 2+) kept high value without scale formation on the membrane surface. Through the EDIR operation, the process performance was affected by polarity reversal periods, and the operating polarity reversal period was determined to 40min or shorter in this study.In the long term EDIR experiments with different cation exchange membranes, the homogeneous membranes showed marginally higher removal efficiency compared to the heterogeneous membrane. The scale powders and the surface of scaled membrane were analyzed using electron microscopes and it was observed that the scales formed as carbonate of divalent cations. The EDIR results showed the feasibility of the EDIR system for use in water softening process without significant scale formation even in a relatively high concentration. © 2011 Elsevier B.V..
Hwang K.-L.,Seoul National University |
Bang C.-H.,Korea Environment Corporation |
Zoh K.-D.,Seoul National University
Bioresource Technology | Year: 2016
The nitrous oxide (N2O) and methane (CH4) emissions were measured from a municipal wastewater treatment plant (WWTP) using a flux chamber to determine the emission factors. The WWTP treats sewage using both the activated-sludge treatment and anaerobic/anoxic/aerobic (A2O) methods. Measurements were performed in the first settling, aeration, and secondary settling basins, as well as in the sludge thickener, sludge digestion tank, and A2O basins. The total emission factors of N2O and CH4 from the activated-sludge treatment were 1.256gN2O/kg total nitrogen (TN) and 3.734gCH4/kg biochemical oxygen demand (BOD5), respectively. Those of the advanced treatment (A2O) were 1.605gN2O/kg TN and 4.022gCH4/kgBOD5, respectively. These values are applicable as basic data to estimate greenhouse gas emissions. © 2016 Elsevier Ltd.
Choi E.,Korea Environment Corporation |
Choi K.,Seoul National University |
Yi S.-M.,Seoul National University
Atmospheric Environment | Year: 2011
Hourly concentrations of non-methane hydrocarbons (NMHCs) were collected at a background monitoring site between April of 2004 and March of 2005 and at suburban and urban sites between March and December of 2006. The sources of NMHCs were identified and associated health risks through the inhalation pathway were evaluated. Positive matrix factorization (PMF) results showed that solvent sources account for the largest portion of the total NMHCs at suburban and urban areas in South Korea, and the risk assessment combined with the PMF results indicated that risk-weighted contributions of solvent sources were enhanced compared to the absolute contribution (from 52% to 68% in suburban areas and from 47% to 80% in urban areas). Carcinogenic risk due to benzene exposure exceeded the one-in-a-million (i.e., 10 -6) cancer benchmark at all three study sites, and the fractions of the population with greater than the benchmark level were 87%, 99%, and 98% in the background, suburban, and urban sites, respectively. Common benzene sources of three study sites were predicted to be Shandong in China based on the 120 h potential source contribution function (PSCF) analysis. To prioritize management options for NMHC sources, risk term may give more meaningful information than amount term. This study suggests that controlling solvent sources would be better option for the mitigation of non-carcinogenic health risk from airborne NMHCs. In addition, the identification of benzene sources using PSCF can be used to assist policymakers in developing regional measures to reduce benzene. © 2010 Elsevier Ltd. All rights reserved.
Choi E.,Seoul National University |
Heo J.-B.,Seoul National University |
Hopke P.K.,Clarkson University |
Jin B.-B.,Korea Environment Corporation |
Yi S.-M.,Seoul National University
Water, Air, and Soil Pollution | Year: 2011
Hourly concentrations of non-methane hydrocarbons (NMHCs) recorded between June and August 2006, at two monitoring sites (Gijang and Jin) in Busan were analyzed to examine the characteristics and photochemical reactivity of NMHC sources. The two sites represent urban (Jin) and suburban (Gijang) Busan, which is a typical Korean city. Positive matrix factorization (PMF), applied to identify and apportion the sources of NMHCs, revealed nine sources for Gijang and ten sources for Jin. To explore the contribution of each NMHC source to ozone formation at the two sampling sites, the ozone formation potential was estimated for each source. The largest contributors to ozone formation were sources characterized by 1,2,3-trimethylbenzene (26.4%) at Gijang and by toluene, ethylbenzene, and xylenes (22.5%) at Jin, which were composed mostly of heavy hydrocarbons and aromatics. Secondary sources included two coating sources (20.9%, 12.2%) and vehicle exhaust (10.3%) at Gijang and a source represented by toluene (17.4%), vehicle exhaust (15.9%), and a coating-2 source (9.6%) at Jin. Conditional probability function (CPF) and potential source contribution function (PSCF) analysis methods were used to identify the directions of local sources and to locate potential source regions, respectively. The CPF and PSCF results agreed well for the majority of sources resolved by PMF and thus were very useful in identifying the major sources contributing to ozone formation at the two study sites. © 2010 Springer Science+Business Media B.V.
Korea Environment Corporation, Electronics and Telecommunications Research Institute | Date: 2012-01-23
An apparatus and method are provided, which predict total nitrogen using general water quality data measured in real time. The total nitrogen prediction apparatus may include a regression model selection unit to select a regression model comprising general data of at least one water quality based on a correlation coefficient of the general data of at least one water quality, a quality-of-fit evaluation unit to evaluate quality of fit of the selected regression model, a regression model change unit to determine whether to change the regression model based on the quality of fit and change the regression model according to the determination result, and a total nitrogen prediction unit to predict total nitrogen of a body of water based on the regression model.
Park S.,Gwangju Institute of Science and Technology |
Yasin M.,Gwangju Institute of Science and Technology |
Kim D.,Korea Institute of Energy Research |
Park H.-D.,Korea University |
And 3 more authors.
Journal of Industrial Microbiology and Biotechnology | Year: 2013
A gas-lift reactor having a high mass transfer coefficient (k L a = 80.28 h-1) for a relatively insoluble gas (carbon monoxide; CO) was used to enrich (homo)acetogens from animal feces. Samples of fecal matter from cow, rabbit, chicken, and goat were used as sources of inoculum for the enrichment of CO and H2 utilizing microbial consortia. To confirm the successful enrichment, the Hungate roll tube technique was employed to count and then isolate putative CO utilizers. The results of this work showed that CO and H2 utilizing consortia were established for each inoculum source after 8 days. The number of colony-forming units in cow, rabbit, chicken, and goat fecal samples were 3.83 × 109, 1.03 × 10 9, 8.3 × 108, and 3.25 × 108 cells/ml, respectively. Forty-two colonies from the animal fecal samples were screened for the ability to utilize CO/H2. Ten of these 42 colonies were capable of utilizing CO/H2. Five isolates from cow feces (samples 5, 6, 8, 16, and 22) were highly similar to previously unknown (homo)acetogen, while cow-7 has shown 99 % similarity with Acetobacterium sp. as acetogens. On the other hand, four isolates from chicken feces (samples 3, 8, 10, and 11) have also shown high CO/H2 utilizing activity. Hence, it is expected that this research could be used as the basis for the rapid enrichment of (homo)acetogenic consortia from various environmental sources. © 2013 Society for Industrial Microbiology and Biotechnology.
Eom S.-Y.,Chungbuk National University |
Yim D.-H.,Chungbuk National University |
Lee C.-H.,Korea Environment Corporation |
Choe K.-H.,Chungbuk National University |
And 4 more authors.
PLoS ONE | Year: 2015
Background Few studies in epidemiology have evaluated the effects of gene-environment interaction on oxidative stress, even though this interaction is an important etiologic factor in lung carcinogenesis. We investigated the effects of the genetic polymorphisms of paraoxonase 1 (PON1), smoking, and the interaction between the two on lung cancer risk and oxidative stress. Methods This study's subjects consisted of 416 newly diagnosed lung cancer patients and an equal number of matched controls. The GoldenGate assay was used for genotypic analyses of the PON1 gene. Urinary 8-hydroxydeoxyguanosine (8-OHdG) and thiobarbituric acid reactive substances levels were measured as indicators of oxidative stress. Results The PON1 rs662 AA genotype showed a significantly lower risk of lung cancer than the GG genotype (OR = 0.60, 95% CI: 0.36-0.99). The protective effect of the PON1 rs662 AA genotype on lung cancer risk was limited to non-smokers. Lung cancer patients who had the rs662 A allele showed a dose-dependent association between smoking status and oxidative stress markers. Among non-smoking lung cancer patients, urinary 8-OHdG levels were significantly lower in individuals with the rs662 GA and AA genotypes than in those with the GG genotype. Furthermore, we found a significant interaction effect between PON1 rs662 and smoking status on urinary 8-OHdG levels in lung cancer patients. Conclusions Our results suggest that the protective effect of PON1 rs662 SNP against lung carcinogenesis and the induction of oxidative stress might be modulated by the interaction between PON1 genetic polymorphisms and tobacco smoking. © 2015 Eom et al.
Kim W.,Chosun University |
Park J.M.,Chosun University |
Gim G.H.,Chosun University |
Jeong S.-H.,Chosun University |
And 3 more authors.
Bioprocess and Biosystems Engineering | Year: 2012
Culture conditions for the mass production of three green algae, Chlorella sp., Dunaliella salina DCCBC2 and Dunaliella sp., were optimized using a response surface methodology (RSM). A central composite design was applied to investigate the effects of initial pH, nitrogen and phosphate concentrations on the cultivation of microalgae. The optimal growth conditions estimated from the design are as follows: Chlorella sp. (initial pH 7.2, ammonium 17 mM, phosphate 1.2 mM), D. salina DCCBC2 (initial pH 8.0, nitrate 3.3 mM, phosphate 0.0375 mM) and Dunaliella sp. (initial pH 8.0, nitrate 3.7 mM, phosphate 0.17 mM). Culturing the microalgae with the optimized conditions confirmed that the maximum growth rates were attained for these parameters. The optimum CO 2 concentrations of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 1.0, 3.0 and 1.0% (v/v), respectively. The specific growth rates (l) of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 0.58, 0.78 and 0.56 day -1, respectively, and the biomass productivities were 0.28, 0.54 and 0.30 g dry cell wt l -1 day -1, respectively. The CO 2 fixation rates of Chlorella sp., D. salina DCCBC2 and Dunaliella sp. were 42.8, 90.9 and 45.5 mg l -1 day -1, respectively. Mixotrophic cultivation of Chlorella sp. with glucose increased biomass productivity from 0.28 to 0.51 g dry cell wt l -1 day -1. However, D. salina DCCBC2 and Dunaliella sp. were not stimulated by several organic compounds tested. © Springer-Verlag 2011.
Park S.-S.,77 Yongbong Ro |
Kim J.-H.,77 Yongbong Ro |
Kim J.-H.,Korea Environment Corporation
Atmospheric Environment | Year: 2014
To examine the formation pathways of two size-resolved water-soluble organic carbon (WSOC) fractions, a total of 16 sets of size-segregated aerosol samples were collected using a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) at a roadway site in Korea from September 29 to October 29, 2010. A XAD7HP (non-ionic aliphatic acrylic polymer) resin column was used to separate the filtered extracts into hydrophilic (WSOCHPI) and hydrophobic (WSOCHPO) WSOC fractions. Also the size distributions of water-soluble inorganic species and oxalate were examined to determine the formation pathways of size-resolved WSOCHPI and WSOCHPO fractions.The size distribution of WSOCHPI showed a dominant mode at 0.55μm, while the WSOCHPO had dominant modes at both 0.17-0.32μm and 0.55μm. On the basis of the size distribution characteristics, it was found that the formation pathways of both WSOCHPI and WSOCHPO were dependent on the particle size; in the condensation mode (0.17-0.32μm), both the WSOCHPI and WSOCHPO could be produced through atmospheric processes similar to those of SO42- and oxalate, which were derived from the gas-phase oxidations of organic compounds. In the droplet mode (0.55-1.8μm), the cloud processing of both the organic compounds and biomass burning emissions could be a major pathway for the WSOCHPI formation. However, the droplet mode WSOCHPO was likely produced through cloud processing and heterogeneous reactions or aerosol-phase reactions. In the coarse mode (>3.1μm), the WSOCHPI formation was more likely associated with soil-related particles (Ca(NO3)2 and CaSO4) than with sea-salt particles (NaNO3 and Na2SO4). © 2014 Elsevier Ltd.