• 한국물환경학회지
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• 제26권1호
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• pp.148-155
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• 2010

Water quality and plankton community dynamics after the introduction of two domestic freshwater shellfishes (Unio douglasiae Griffith & Pidgeon and Cipangoplaudina chinese malleata Reeve), were monitored daily in enclosures, which constructed in the tidal zone of eutrophic agricultural reservoir (Shingu reservoir, Korea) for one week between July 31 and August 6, 2007. This biomanipulation study to improve the water quality of eutrophic lake, comprised eight enclosures (duplicate x four kinds), enclosure had no mussels (Control), stocked only with U. douglasiae at density of 60 individuals (UD), stocked only with C. chinese malleata at density of 60 individuals (CCM), and combined-stocked with 30 individuals of UD and 30 individuals of CCM (MIX), respectively. Our results clearly indicate that UD strongly decreased the concentration of chlorophyll-a and increased the water transparency, whereas CCM and MIX (included CCM) did increase algal density or decrease transparency, due perhaps to the disturbance of C. chinese malleata. Therefore, the field application of shellfish to enhance the water quality of eutrophic agricultural reservoir, should consider the grazing characteristics of biological control agents, especially active moving animals like snail.

• 한국해양바이오학회지
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• 제10권2호
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• pp.91-96
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• 2018

There are many eutrophic lakes by point and non-point pollution sources such as in dustrial waste water, domestic raw sewage, and mucks. The eutrophic lakes not only cause algal blooms but also destroy the ecosystem in the lakes due to high nutrient concentrations. The purpose of this study was to improve water quality in eutrophic lakes by cultivating microalgae using photobioreactors (PBRs) with selectively permeable mesh (SPM), supplying nutrients in the lake and inhibiting cell leakage by diffusion and water permeability. Chlorella vulgaris, was cultivated using PBRs with SPM installed in Inkyung Lake located in Inha university, Incheon, Korea. When cultivating C. vulgaris, $8.3g/m^2/day$ of average biomass productivity was obtained at 3 days. Furthermore, concentrations of total nitrogen and phosphorus were reduced by 35.7% and 84.2%, respectively, compared to initial condition and water quality in eutrophic lake was improved to oligotrophic environment. These results suggest that microalgal cultivation using PBRs with SPM in the lake could produce microalgal biomass as well as improve water quality by decreasing nutrient concentrations.

• 한국환경과학회지
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• 제16권3호
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• pp.357-367
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• 2007

Recently, eutrophication or lake and reservoir has become serious problem to man who want use that water for several purpose. In order to solve the eutrophication problem, the trophic state of that eutrophic lake and reservoir should be measured properly. For the purpose of this, various method to indicate the trophic state of lake and reservoir was developed by many researchers. This research was conducted to evaluate characteristics and eutrophication of water qualitymfor small scale reservoir in Kunsan. On-site investigation to 5 reservoirs and laboratory experiment were carried out during four seasons from November, 2003 to July, 2004. Twelve items measured field ana a laboratory. Measured data was analyzed to quantitative method by multivariate approach and eutrophication index. The result is summarized as following. 1) Showing the characteristics of water quality for reservoir in Kunsan, Okgu reservoir and Oknua reservoir was exceeded 4 grades of agricultural water standard in TP, TN and COD. This means that eutrophication was gone much, therefore, water-purity control of reservoir need. While, Mije reservoir that is used to Kunsan citizens' recreation was good in water quality. But, water quality exceeded 4 grades of agricultural Dater standard sometimes. 2) As a results of correlation analysis between variables of water qualify, Interrelation between variables which is connected with eutrophication was expressed good relationship as above 6.000 in correlation coefficients. The correlation coefficient(r) between COD and chlorophyll-a, total phosphorus and chlorophyll-a, total nitrogen and chlorophyll-a were 0.750, 0.720 and 0.600 respectively. Therefore, Change of water quality can grasp according to eutrophication progress degree. 3) If do evaluate to eutrophication by quantitative method which is proposed by OECD, US-EPA and Forsberg & Ryding, in the case of chlorophyll a, Okgu, Oknua and Daewi reservoir was eutrophic state and Mije and Geumgul reservoir was mesotrophic state. But, estimation by TN and TP showed highly eutrophic state (hypereutrophic) in all reservoirs. 4) If do evaluate by eutrophication index which is Carlson's TSI, revised carlson TSI and Walker's index, in the case of chlorophyll a, TSI values of Okgu, Oknua and Daewi reservoir is eutrophic state more than 50 and Mije and Geumgul reservoir was mesotrophic state as range of $40{\sim}50$ in TSI value. But, in the case of TP as nutrients, all reservoirs showed highly eutrophic state which was exceed to 70 in TSI value. According to above results, the water quality for small scale reservoirs in Kunsan is progressing by trophic state. therefore, for continuous use as agriculture water, we had better do establishment of management plan about water quality.

• 한국물환경학회지
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• 제26권3호
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• pp.518-524
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• 2010

Continuous removal of organic matters (CROM) using freshwater bivalve Anodonta woodiana was operated to evaluate the effect of water current on the water quality improvement (clearance) of eutrophic lake. The CROM system comprised three treatment steps such as flow control, treatment and analysis, and operated at the two different currents ($24L\;h^{-1}$ and $48L\;h^{-1}$) with mussels at density of $312.5indiv.\;m^{-2}$ for 12 consecutive days. Water quality including suspended solids (SS) and chlorophyll-a (Chl-a) was daily measured at the same time. Results indicate that although both the system strongly decreased the concentration of SS and chl-a, a slow CROM system was more effective to diminish the SS contents than a fast CROM system; 82% and 66%, respectively (ANOVA, P<0.0001). Clearance rates, based on chl-a, were also significantly higher in a slow system than a fast system (ANOVA, P<0.0001), although the mussel mortality was conversely. In both systems, there showed a remarkable excretion of dissolved inorganic nutrients (i.e. $NH_3-N$ and $PO_4-P$), while a slow CROM system was higher than a fast system, significantly (ANOVA, P<0.0001). Therefore, it may suggest that a slow current CROM system is more suitable to maximize the efficacy of water quality improvement, but further study is needed to diminish the mortality of mussel and to reuse the nutrient released during the operation.

• 생태와환경
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• 제46권2호
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• pp.225-233
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• 2013

부영양호 신갈지의 수질개선을 위하여 이미 개발된 천연물질 혼합제(PMC)의 수질개선능(WQI)에 수온변화가 어떠한 영향을 미치는지 현장실험을 실시하였다. 실험결과 식물플랑크톤, BOD, 총인 등은 $20^{\circ}C$ 이하에서는 70% WQI 이상을 보였으나 $25^{\circ}C$ 이상에서는 40% WQI 이하로 오히려 감소하였다. 한편 수온의 증가에 따라 남조류에 대해서는 WQI는 감소하였고, 규조류는 수온변화에 상관없이 90% 이상 높은 WQI를 나타냈으며, 박테리아와 총 질소는 수온과 상관없이 매우 낮은 WQI를 보였다. 이상의 결과들은 PMC의 수질개선능이 수온과 밀접한 관계를 가지며, $25^{\circ}C$ 이상의 고온기에 Microcystis aeruginosa가 우점하는 남조대발생보다 겨울철 저온기에 우점하는 규조류에 더 효과적일 것으로 판단되었다.

• 한국물환경학회지
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• 제24권1호
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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.

• ALGAE
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• 제22권2호
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• pp.69-85
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• 2007

From six reservoirs in Gyeonggi-do, we have collected the distribution and standing crop of phytoplankton since Nov. 2005 through Sep. 2006. As a result, the phytoplankton appeared totally 340 taxa belong to 7 classes, 15 orders, 5 suborders, 32 families, 4 subfamilies, 84 genera, 283 species, 43 varieties, 9 forms and 5 unidentified species. The standing crop was shown as minimum was 0.3 × 106 cells and maximum was 5,950 × 106. The relation of standing crop with TN, TP and Chl-a showed as positive. Total 12 taxa including 2 taxa of blue-green algae occurred to every seasons at six lakes, and it was thought that they distributed in mesotrophic state. Also, Achnanthes minutissima, Aulacoseira granulata, Eudorina elegans, Gloeocystis ampla, Pandorina morum, Pediastrum simplex var. duodenarium, Scenedesmus ecornis were regarded as the indicators of eutrophic state. From the estimation of LTSI and TSI, it was shown that the rest of lakes except for Idong reservoir of winter were eutrophic states.

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.897-904
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• 2007

The aim of this paper is to discuss the methodology of our investigation of the dynamics of protein degradation and the total in situ protealytic activity in meso/eutrophic, eutrophic, and hypereutrophic freshwater environments. Analysis of the kinetics and rates of enzymatic release of amino acids in water samples preserved with sodium azide allows determination of the concentrations of labile proteins $(C_{LAB})$, and their half-life time $(T_{1/2})$. Moreover, it gives more realistic information on resultant activity in situ $(V_{T1/2})$ of ecto- and extracellular proteases that are responsible for the biological degradation of these compounds. Although the results provided by the proposed method are general y well correlated with those obtained by classical procedures, they better characterize the dynamics of protein degradation processes, especially in eutrophic or hypereutrophic lakes. In these environments, processes of protein decomposition occur mainly on the particles and depend primarily on a metabolic activity of seston-attached bacteria. The method was tested in three lakes. The different degree of eutrophication of these lakes was clearly demonstrated by the measured real proteolytic pattern and confirmed by conventional trophic state determinants.

• 상하수도학회지
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• 제18권2호
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• pp.247-253
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• 2004

Major species of Lake Deganuma has varied depending on the season. Namely, there are Micractinium pusillum, chlorella., Scenedesmus sp. shown up in spring season, Microcystis aeruginosa, Microcystis wesenbergii, Anabena spiroides in summer and autumn season and Cyclostephanos invisitatus, Diatoma in winter season in the Lake. As the number of plankton increased, the zeta potential on their surface of them decreased. For this reason, they were dispersed in the lake though the population increased. Zeta potential of M. aeruginosa showed -20mV when their outer size got smaller. As for coagulant dosing in DAF, large amount of coagulant was effective to get lots of sludge during water treatment.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 1998년도 수산관련공동학술대회발표요지집
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• pp.379.1-379
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• 1998