• Title, Summary, Keyword: Autochthonous Resources

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A Study on Water Quality Modeling for Autochthonous BOD Effect in Namgang Dam Downstream (자생 BOD 영향에 따른 남강댐 하류부 수질모델링 연구)

  • Hwang, Soo Deok;Lee, Sung Jun;Kim, Young Do;Kwon, Jae Hyun
    • Journal of Korea Water Resources Association
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    • v.46 no.4
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    • pp.413-424
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    • 2013
  • The TMDL, the watershed-oriented water quality management policy, was introduced to inhibit the total amount of pollutant loading generation, and to develop the region environmentally friendly. However, despite the implementation of TMDL, the water quality of Nam river downstream has worsened continuously since 2005. Diverse pollution sources such as cities and industrial zone are scattered around the Nam river. Eutrophication are caused due to deterioration of water quality by low velocity. BOD concentrations in the eutrophic waters affected by the incoming BOD and the autochthonous BOD by the production of phytoplankton. In this study, the quantitative relation of incoming BOD and autochthonous BOD was analyzed for water quality management. The influence of autochthonous BOD was analyzed using QUALKO2 and QUAL2E. Considering the effects of Chl.a, BOD concentration from QUALKO2 model simulations is higher than BOD concentration from QUAL2E model. The results of QUALKO2 showed higher correlation with the measured data. Autochthonous BOD needs to be managed to solve the water pollution problem of Nam river downstream, which is looking for ways to reduce Chl.a by using the increase of the dam outflow and the improvement of the water quality from WWTP.

A Numerical Simulation of Multiphase Flow in a Discrete Fracture Network (이산 균열망에서 다상 흐름에 대한 수치모의)

  • Jeong Woo Chang;Hwang Ma ha;Ko Ick Hwan;Song Jai Woo
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.245-249
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    • 2005
  • The numerical simulation of a two-phase flow In a discrete fracture network model is presented in this paper, The purpose of this work is to consider density-driven flows induced by the density difference between hot autochthonous heavy brines and injected cold water. Mechanical consequences of high pressure waves on the fracture permeability and heat exchanges between fluids and rock matrix are neglected in this study. The finite volume method is employed to discretize spatially and the system is solved by using an IMPES(Implicit Pressure-Explicit Saturation) scheme. In order to solve the strong non-linearity of the system, the Newton-Raphson algorithm is used. The well-known Buckeley-Leverett problem is adapted to validate results calculated from the model and a relatively good agreement is obtained.

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Comparative Evaluation of QUAL2E and QUAL-NIER Models for Water Quality Prediction in Eutrophic River (부영양 하천의 수질예측을 위한 QUAL2E와 QUAL-NIER 모델의 비교·평가)

  • Choi, Jungkyu;Chung, Sewoong;Ryoo, Jaeil
    • Journal of Korean Society on Water Environment
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    • v.24 no.1
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    • pp.54-62
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    • 2008
  • It is often believed that a more complex water quality model is better able to simulate reality. The more complex a model, however, the more parameters are involved thus increases the cost and uncertainty of modeling processes. The objective of this study was to compare the performance of two steady-state river water quality models, QUAL2E and QUAL-NIER, that have different complexity. QUAL-NIER is recently developed by National Institute of Environmental Research aiming to enhance the simulation capability of QUAL2E for eutrophic rivers. It is a carbon based model that considers different forms, such as dissolved versus particulate and labile versus refractory, of carbon and nutrients, and the contribution of autochthonous loading due to algal metabolism. The models were simultaneously applied to Nakdong River and their performance was evaluated by statistical verification with field data. Both models showed similar performance and satisfactorily replicated the longitudinal variations of BOD, T-N, T-P, Chl.a concentrations along the river. The algal blooms occurred at the stagnant reaches of downstream were also reasonably captured by the models. Although QUAL-NIER somewhat reduced the magnitude of errors, the hypothesis tests revealed no statistical evidence to justify its better performance. The contribution of autochthonous carbon and nutrient load by algal metabolism was insignificant because the hydraulic retention time is relatively short compare to the time scale of kinetic reactions. The results imply that the kinetic processes included in QUAL-NIER are too complex for the nature and scale of the real processes involved, thus needs to be optimized for improving the modeling efficiency.

Where art thou "the great hiatus?"- review of Late Ordovician to Devonian fossil-bearing strata in the Korean Peninsula and its tectonostratigraphic implications

  • Lee, Dong-Chan;Choh, Suk-Joo;Lee, Dong-Jin;Ree, Jin-Han;Lee, Jeong-Hyun;Lee, Seung-Bae
    • Geosciences Journal
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    • v.21 no.6
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    • pp.913-931
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    • 2017
  • We review paleontologic evidence from the Upper Ordovician to Devonian strata in the Korean Peninsula and discuss their tectonostratigraphic origin. The Upper Ordovician-Devonian fossil-bearing strata are largely distributed in North Korea, and tectonostratigraphically in the southern margin of the Pyeongnam Basin and in the northern part of the Imjingang Belt. The fossils have been regarded as evidence that the "great hiatus" of the middle Paleozoic is not a prevalent phenomenon across the Sino-Korean Block. Examination of selected fossils with stratigraphic and paleogeographic significance reveals that the fossils from the Sangsori, Koksan and Wolyangri series and the Rimjin System are of the Late Ordovician to Devonian and display affinity to those of the coeval strata of South China. In addition, the fossils included within clasts of the Songrim Conglomerate, the basal unit of the Jurassic Taedong System, are of the Silurian to Devonian, which also display affinity to South China. The faunal and floral affinity suggests that the Upper Ordovician to Devonian strata in North Korea most likely formed in a basin(s) of or peripheral to the South China Block, which indicates that the strata are allochthonous, contrary to the traditional interpretation of their autochthonous origin by North Korean geologists. The Permo-Triassic collision between the two Chinese cratons which resulted in the amalgamation of three massifs of the Korean Peninsula is considered to be responsible for the accretion and juxtaposition of the Upper Ordovician to Devonian strata onto the Sino-Korean Block. The autochthonous origin of the strata suggests the absence of the "great hiatus" at least in North Korea, whereas the allochthonous origin its presence across the Sino-Korean Block.

Spatial Distribution of Bacterial Abundance and Production in the Saemangeum Area (새만금 주변 해역에서 박테리아 개체수 및 생산력의 공간 분포)

  • Choi, Dong-Han;Noh, Jae-Hoon
    • Ocean and Polar Research
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    • v.30 no.4
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    • pp.509-518
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    • 2008
  • Distribution of bacterial abundance and production was investigated in seawater around Saemangeum dike 7 times during March, $2007{\sim}July$, 2008. In the inner area of the dike, salinity variation was great due to river runoff from Mangyung and Dongjin Rivers and high chlorophyll a (chl a) concentrations up to $124.3{\mu}g\;l^{-1}$ was found. In the outer area of the dike, salinity was higher than in the inner area of the dike, and chl a was lower up to 10 times than in the inner area of the dike. Thus, the area of Saemangeum showed meso- to hypereutrophic conditions. Bacterial abundance and production ranged from 0.3 to $4.3{\times}10^9\;cells\;l^{-1}$ and from 5.2 to $570 pmol\;l^{-1}h^{-1}$ in outer area of the dike, respectively, while in the inner area of the dike bacterial abundance and production was 3 to 4 times higher ($0.4{\sim}12.7{\times}10^9\;cells\;l^{-1}$ and $12.3{\sim}1309\;pmol\;l^{-1}h^{-1}$, respectively) than those in the outer area. In both areas, bacterial abudance and production was highest in summer and lowest in winter. However, the variations of bacterial parameters was very large in each season. These large variations seemed to be related with the supply of organic matter. Bacterial abundance and production showed significant negative correlations with salinity in the inner area, suggesting that allochthonous organic matter input by river runoff could be an important factor in regulating the distribution of bacterial abundance and production. In addition, bacterial production also correlated positively with chl a in the inner area, suggesting that autochthonous substrate might be another regulating factor of bacterial growth in the area. These results suggest that the supply of both allochthonous organic substrates introduced by river runoff and autochthonous substrates produced by phytoplankon could be important in regulating bacterial growth and utilization of organic matter in the area. Thus, to manage water quality in the inner area of dike, it seems to be important to lower the load of both organic and inorganic nutrients from adjacent rivers.

A Study on the Origin of Organic Matter in Seawater in Korean Estuaries Using Chemical Oxygen Demand (화학적산소요구량을 이용한 하구해역의 해수중 유기물 기원 고찰)

  • Kim, Young-Sug;Koo, Jun-Ho;Kwon, Jung-No;Lee, Won-Chan
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.6
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    • pp.735-749
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    • 2018
  • In this study, one studied the principal factors and water-quality components that determine the concentration of chemical oxygen demand (COD) in seawater in estuaries, such as the Han, Geum, Youngsan, Seomjin, and Nakdong rivers in Korea. The principal factors determining the concentration of COD in seawater indicated by the principal component analysis were salinity, exogenous origin and autochthonous resources based on chlorophyll-a. Moreover, organic matter in the submarine sediment layer also had a secondary effect. Regression slope assessed the contribution of water-quality components to determine the concentration of COD in the estuary. One found that the effect of salinity on the overall survey was significant. Moreover, the effect of chlorophyll-a was also appeared in April and August. In each estuary, the most significant contribution factor was chlorophyll-a in the Nakdong River and salinity in the Han and Yongsan rivers. The contribution of salinity and chlorophyll-a were found to be the largest in the Geum River. The salinity and chlorophyll-a in the Seomjin River showed a low contribution.

Development and Application of Dynamic Water Quality Model in Nakdong River (동적수질해석모형의 개발과 낙동강에의 적용)

  • Kwon, Na-Young;Choi, Hyun-Gu;Yu, Jae-Jung;Han, Kun-Yeun
    • Journal of Korea Water Resources Association
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    • v.43 no.3
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    • pp.283-294
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    • 2010
  • The objective of this study is to develop an accurate and stable dynamic water quality model which is capable of reflecting various flows and irregular cross sections and handling numerical oscillations under the low flow conditions. In order to solve the oscillation problem under the low flow conditions, diffusive wave method was applied to the low flow condition in developing a hydraulic model, DyHYD. DyQUAL is also developed as a water quality model to calculate up to 12 water quality variables including autochthonous BOD, water temperature, DO, TN and TP. The developed model is applied to both hypothetical river channels and actual Nakdong river watershed. Additionally, the applicability and reliability of the models are verified by comparing simulation results with observed values. Nash-Sutcliffe coefficients are estimated by comparison between simulation results and observed values. In the calibration and verification process, the coefficients varies from 0.391 to 0.591 and 0.704 to 0.902 for discharge, BOD, TN and TP, respectively.

Bioaugmentation Treatment of Mature Landfill Leachate by New Isolated Ammonia Nitrogen and Humic Acid Resistant Microorganism

  • Yu, Dahai;Yang, Jiyu;Teng, Fei;Feng, Lili;Fang, Xuexun;Ren, Hejun
    • Journal of Microbiology and Biotechnology
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    • v.24 no.7
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    • pp.987-997
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    • 2014
  • The mature landfill leachate, which is characterized by a high concentration of ammonia nitrogen ($NH_3$-N) and humic acid (HA), poses a challenge to biotreatment methods, due to the constituent toxicity and low biodegradable fraction of the organics. In this study, we applied bioaugmentation technology in landfill leachate degradation by introducing a domesticated $NH_3$-N and HA resistant bacteria strain, which was identified as Bacillus cereus (abbreviated as B. cereus Jlu) and Enterococcus casseliflavus (abbreviated as E. casseliflavus Jlu), respectively. The isolated strains exhibited excellent tolerant ability for $NH_3$-N and HA and they could also greatly improved the COD (chemical oxygen demand), $NH_3$-N and HA removal rate, and efficiency of bioaugmentation degradation of landfill leachate. Only 3 days was required for the domesticated bacteria to remove about 70.0% COD, compared with 9 days' degradation for the undomesticated (autochthonous) bacteria to obtain a similar removal rate. An orthogonal array was then used to further improve the COD and $NH_3$-N removal rate. Under the optimum condition, the COD removal rate in leachate by using E. casseliflavus Jlu and B. cereus Jlu increased to 86.0% and 90.0%, respectively after, 2 days of degradation. The simultaneous removal of $NH_3$-N and HA with more than 50% and 40% removal rate in leachate by employing the sole screened strain was first observed.

Diagnosis of Water Environment and Assessment of Water Quality Restoration in Lake Shihwa (시화호의 수환경 진단과 수질회복 평가)

  • Kim, Dong-Seop;Go, Seok-Gu
    • Journal of Korea Water Resources Association
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    • v.33 no.5
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    • pp.551-559
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    • 2000
  • In order to diagnose the water environment and assess the water quality restoration, long term trend of water environment has been surveyed at 3-R stations from 1994 to 1999 in Lake Shihwa. Annual mean values of $COD_{Mn}$, Chlorophyll a, total nitrogen, total phosphorus and Secchi depth are ranged in 5.2-15.1 mg/L, 7.3-14R.1 jlg/L, 1.50-4.84 mgN/L, 0.055-0.281 mgP/L and 0.5 -1.4 m, respectively, during the study periods. Carson's trophic state indeies were varied from mesotrophy in 1994 and 1995, hyper-eutrophy in 1996 and 1997, to meso eutrophy in 199R and 1999. After dike construction, water quality were rapidly deteriorated by allochthonous and autochthonous loading of high nutrients and organic carbon. Eutrophication phenomena were characterized by massive phytoplankton blooms and high concentration of COD. However, after onset of restoration program, lake water quality was rapidly restored to the level of just after sea-dike construction. The diversion of waste water inflowing from the Panwol and the Sihwa industrial districts which was started from March, 1997 has contributed to improve water quality in the surface layer. And the tidal mixing (sea water inflowing) through the continuous gate operation was the most effective measure to the whole lake restoration.ration.

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Isotopic Determination of Terrestrial Food Sources for a Brackish Water Clam Corbicula japonica PRIME in an Estuarine System of Youngil Bay, Korea

  • Lee, Won-Chan;Park, Jin-Il;Choi, Woo-Jeung;Kim, Young-Seop;Lee, Pil-Yong;Kang, Chang-Keun
    • Journal of the korean society of oceanography
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    • v.35 no.1
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    • pp.56-64
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    • 2000
  • The importance of terrestrial organic matter as a food source for a brackish water clam Corbicula japonica was evaluated using stable carbon isotope ratios (${\delta}^{13}$C) in its tissues and potential food resources in an estuarine system of Youngil Bay, Korea. Suspended particulate organic matter (POM) had distinct ${\delta}^{13}$C values from riverine (-31.8 to -27.2%$_o$) to marine waters (-21.0 to -16.6%$_o$). Estuarine macroalgae had a wide ${\delta}^{13}$C range of -22.8 to -15.0%$_o$. The ${\delta}^{13}$C values of riverine POM were more negative than that of riverine phytoplankton (-26.5 to -24.2%$_o$) but similar to that of freshmarsh plant species (-29.1 to -27.5%$_o$ for Phragmites communis and -28.5 to -27.0%$_o$ for Salix gracilistyla), These ${\delta}^{13}$C values suggest that the POM transported by the Hyungsan River is predominantly of terrestrial origin rather than riverine autochthonous sources. The ${\delta}^{13}$C values of Corbicula japonica tissues (-28.7 to -27.2%$_o$) were most similar to values for riverine POM and freshmarsh plants. There was no significant difference in the isotopic composition of the clam individuals. The results indicate a predominant contribution of organic carbon derived from terrestrial and fresmarsh plant detritus to the diet of Corbicula japonica. Our results also confirm previous suggestion that terrestrial organic matter can be incorporated into estuarine food webs although its role is confined to the upper estuarine reaches.

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