• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.387-394
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• 2007

Despite geographic barriers such as oceans, many freshwater algal species inhabit different continents of the world. A unicellular freshwater alga, Mallomonas caudeata, commonly occurring in Asia, Europe, and America of the northern Hemisphere, is closely related to human life such as monitoring blooms and defecting changes in climates. In order to demonstrate its occurrence in Korea and to infer its phylogeny, we sequenced nuclear SSU and plastid rbcL genes from isolates collected in six different reservoirs. We have also investigated transmission electron microscopy of the Korean isolates. SSU sequences of the species from Korea and USA were almost identical, having pair-wise divergences of 0.06% in SSU and 0.45% in rbcL. Both gene trees revealed that the species was clearly separated from other species of the genus, while the genus was not monophyletic. Rhizoplasts are composed of microfibrils organised in striated rootlets attached to the multilayered plate of basal bodies and arranged on the surface of the nucleus at their distal ends. The rhizoplast constitutes a basal body-nucleus connector similar to that of typical Synurophyceas. The results that Mallomonas was not supported by both SSU and rbeL data sets require a further study with additional taxon sampling.

• Journal of Wetlands Research
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• v.26 no.3
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• pp.245-253
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• 2024

Blue-green algal bloom, or harmful algal bloom has a negative impact on the aquatic ecosystem and purified water supply system due to oxygen depletion in the water body, odor, and secretion of toxic substances in the freshwater ecosystem. This Blue-green algal bloom is expected to increase in intensity and frequency due to the increase in algae's residence time in the water body after the construction of the Nakdong River weir, as well as the increase in surface temperature due to climate change. In this study, in order to respond to the expected increase in green algae phenomenon, an algal bloom forecast system based on hydro-meteorological factors was presented for preemptive response before issuing a algal bloom warning. Through polyserial correlation analysis, the preceding influence periods of temperature and discharge according to the algal bloom forecast level were derived. Using the decision tree classification, a machine learning technique, Classification models for the algal bloom forecast levels based on temperature and discharge of the preceding period were derived. And a algal bloom forecast system based on hydro-meteorological factors was derived based on the results of the decision tree classification models. The proposed algae forecast system based on hydro-meteorological factors can be used as basic research for preemptive response before blue-green algal blooms.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.3
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• pp.97-109
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• 2010

This study analyzed stratification and destratification processes in the Kangjin Bay (KB), South Sea, Korea, driven by the Nam Gang Dam water discharge based on numerical modeling experiments. Model performances were evaluated in terms of skill scores for elevation, velocity, temperature and salinity, with scores mostly exceeding 90%. The models reproduced the tidal current, density-driven and wind-driven current. The stratification by fresh water input and destratification by the wind mixing was assessed in terms of the characteristic Richardson number (Ri) in that Ri increased from 0 to 7~20 during the Dam water discharge period, while vertical mixing and destratification followed by the typhoon passage showed Ri, 0 to 2.

• Journal of Korea Water Resources Association
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• v.45 no.9
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• pp.915-928
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• 2012

Han River estuary (HRE) is located at the middle of the western coast of Korea, and tidal currents were measured at 4 stations in this estuary during the winter season, and previously observed tide data was analyzed. The results of amplitude ratio of $M_4/M_2$ showed that increasing upward to estuary in the HRE. Tide harmonic constants of relative phase $2M_2-M_4$ represent flood dominance, with under 180 degree. But this method has a limit of analysis that typically based on the non-linear distortion of the tidal current in tidal lagoon system where freshwater discharge is assumed to be relatively small. The results of statistically tidal current data indicated that ebb current velocity would be great unlike tide data. Ebb and flood duration time is calculated by slack time of tidal current showed that ebb duration time is longer than flood. The results of correlation of analysis show high value (0.9) between tidal current stations from Incheon harbor to north entrance of Yeomha channel. We reconstructed to find the reasons for the features of ebb dominance the results of harmonic analysis. As major component ($M_2$) in combination with shallow water component ($M_4$), the tidal curve was presented flood dominance that has a flood current is stronger. However, these curve were changed to ebb dominance add up the non-harmonic components that had ebb direction flow by calculated tidally averaged current. The characteristic of enhancement on ebb is showed around the Yeomha channel in the HRE, because averaged flow which acts seaward such as long-term tidal current components due to non-linear effect and freshwater which overcome the flood current.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.206-212
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• 2000

Since some cyanobacterial isolates under selective culturing conditions are lacking of characteristic specialized cells or showing altered morphology, the morpho-taxonomic criteria are not accurate enough to discriminate between species. Instead of morphological parameters, a method based on the single or the combination of repetitive oligonucleotides in a single PCR, repetitive oligonucleotides-primed PCR (ROP-PCR), was applied to generate DNA profiles for members of the cyanobacterial genera Anabaena and Oscillatoria, both of which are responsible for causing poisonous blooms in various freshwater systems. ROP-PCR performed on 10 isolates of the cyanobacteria with ERIC and REP sequences from gram-negative bacteria, STRR1A and LTRR sequences derived from cyanobacterial genome, and eukaryotic repetitive sequences, led to the identification of distinct genotypes, and provided specific and repeatable DNA fingerprints for cyanobacterial isolates. Grouping analysis of cyanobacterial isolates showed a signifiant difference depending on the primer used in PCR.

• Korean Journal of Microbiology
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• v.44 no.3
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• pp.251-257
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• 2008

Four potential microcystin-producing cyanobacteria were isolated from large reservoirs which act as sources of drinking water supply in Korea. Strain DC-2, YD-l, and YD-6 were closely related to Microcystis aeruginosa based on the analysis of l6S rRNA gene and mcyA gene sequences. mcyA gene sequence of YDS2-3, isolated from Yongdam Reservoir, was closed to that of M. aeruginosa, whereas l6S rRNA gene sequence was not related to the known sequences of microcystin-producing cyanobacteria indicating this strain can be a novel cyanobacterium belonging to the genus Microcystis. When mcyA gene sequences of isolated cyanobacteria were compared with the mcyA gene sequence library of two reservoirs, the sequence of DC-2 matched with the dominant ones.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.2
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• pp.53-64
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• 2013

This study analyzed the ADCP records along with wind by KMA and discharge records at Seosan A-, B-district tide embankment by KRC for 33 days obtained in the Chunsu Bay, Yellow Sea, Korea spanning from July 29 to August 30, 2010. Various analyses include descriptive statistics, harmonic analysis of tidal constituents, spectra and coherence, complex correlation, progressive vector diagram and cumulative curves to understand the tidal and sub-tidal current characteristics caused by local wind and discharge effect. Observed current speed ranges from -30 to 40 (cm/sec), with standard deviation from 1.7 (cm/sec) at bottom to 18.7 (cm/sec) at surface. According to the harmonic analysis results, the tidal current direction show NNW-SSE. The magnitudes of semi-major axes range from 9.4 to 14.8 (cm/sec) for M2 harmonic constituent and from 4.4 to 7.0 (cm/sec) for S2, respectively. And the magnitudes of semi-minor axes range from 0.1 to 0.5 (cm/sec) for M2 and from 0.4 to 1.4 (cm/sec) for S2, respectively. In the spectral analysis results in the frequency domain, we found 3~6 significant spectral peaks for band-passed wind and residual current of all depth. These peak periods represent various periodicities ranging from 2 to 8 (days). In the coherency analysis results between band-passed wind and residual current of all depth, several significant coherencies could be resolved in 3~5 periodicities within 2.8 (days). Highest coherency peak occurred at 4.6 (day) with 1.2-day phase lag of discharge to band-passed residual current. The progressive vector of wind and residual current travelled to northward at all layers, and the travel distance at middle layer was greater than surface layer distance. The Northward residual current was caused by a seasonal southern wind, and the density-driven current formed by fresh water input effected southward residual current. The sub-tidal current characteristics is determined by seasonal wind force and fresh water inflow in the Chunsu Bay, Yellow Sea, Korea.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.233-242
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• 2010

This study was conducted to know that if ionic liquids can be applicable as control agents of harmful algae in water-ecosystem and to find out problems caused by ionic liquid application. Firstly, the differential selectivity of various fresh-water algal species to several 1-alkyl-3-methylimidazolium chloride ionic liquids was investigated. There was a distinct differential response between alkyl chain lengths from butyl to dodecyl and towards the algal organisms : Generally algicidal activity was increased with increase of chain length and among the algae used in this study, Stephanodiscus hantzschii f. tenuis, Oscillatoria tenuis and Spirulina pratensis were most sensitive to 1-dodecyl-3-methylimidazolium chloride (MAIC12), next was Microcystis aeruginosa, and the others were relatively less sensitive to the chemical. The selectivity degree was about ten to twenty times based on the $EC_{80}$ (Effective concentration required for 80% growth inhibition). Secondly, an activity persistence of ionic liquids was investigated in natural mimic condition (using water bottle containing soil-sediments under the greenhouse condition). At the application of $1.0{\mu}g\;mL^{-1}$ of 1-octyl-3-methylimidazolium chloride (MAIC8), the algal growth did not occur at all until 6 days after treatment(DAT) and observed a only little growth at 9 DAT. But the algae grew rapidly after 9 DAT. So at 20 DAT, total chlorophylls was $264.4{\mu}g\;L^{-1}$ and the growth was inhibited by 58.2% compared to untreatment. On the other hand, MAIC12 also had a similar persistence pattern to MAIC8, showing nearly 5 times more activity than MAIC8. At 20 days after $0.2{\mu}g\;mL^{-1}$ application of MAIC12, that is, total chlorophylls was $251.2{\mu}g\;L^{-1}$ and the growth was inhibited by 55.2% compared to untreatment. In summary, 1-alkyl-3-methylimidazolium chloride ionic liquids is likely to be applicable for selective control of harmful algae as potent compounds having long lasting activity. However, the difficulty of degradation seems to be a limiting factor in an eco-friendly application of the compounds.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.251-259
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• 2000

Monthly variations of physico-chemical and biological parameter were determined in near the Kum River mouth at lower discharge period from January 1998 to September 1999. The characteristics of water quality was showed hypertrophic with average values of total nitrogen (TN), total phosphorus (TP), chlorophyll-a and transparency are 3.9 mg N/l, $160\;{\mu}g/l$, $73\;{\mu}g/l$ and 0.8 m, respectively. Among a nitrogen component, inorganic and organic nitrogen comprised 34% and 66% of TN, $NH_4$ and $NO_3$ comprised 30% and 70% of inorganic nitrogen respectively. SRP concentration comprised below 9% of TP. TN/TP and DIN/SRP ratio in winter were higher than in summer. SRSi fluctuation was very wide as ranged from 0 to 3.0 mg Si/l and the highest after flood event in summer. Long-term depleted pattern of Si was observed, that is considered to be important nutrient for algal growth. Chlorophyll-a concentration was very high as $113\;{\mu}g/l$, $162\;{\mu}g/l$ in winter and summer respectively, which persisent bloomed diatom Stephanodiscus and blue-green algae Microcystis. In consequence, water quality management of these periods are considered very important.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1994.05a
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• pp.51-53
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• 1994

담수는 인간의 생존에 필수적인 요소이다. 우리는 매일 일정량의 물을 섭취하고 있으며, 일상에서 직접, 간접적으로 물과 관련되지 않고서는 생활할 수 없다. 지구 표면의 약 70%가 물로서 덮여 있다고는 하지만 인간의 생활에 직접적인 이용가치가 있는 담수(지표수)는 전체 물의 용적의 2%에 지나지 않는다. 한국의 연평균 강수량은 1,274mm로서 세계 연평균 강수량인 970mm보다 많은 편이나 인구 1인당 연간 강수량은 약 3,000m3으로서 세계 평균인 34,000m3의 11분의 1에 지나지 않는다. 수자원총량중 지하침투와 증발에 의해 손실되는 양을 제외한 하천유출량은 전체의 55%인 697억m3으로서 이것이 곧 가용수자원량이다. 그러나 하절기 강우집중도가 높은 우리나라 실정에서는 가용수자뭔량중 수자원총량의 37%가 홍수시 유출되고 실제 이용량은 수자원총량의 18%인 230억m3에 불과하여 인구증가와 함께 수자원의 가치가 더욱 증대하고 있는 실정이다. 더우기 지하수 이용량은 19억m3에 불과함에 따라 우리나라는 실제 이응수자 원량의 90% 이상을 지표수에 의존하고 있으며, 그 중 약 40%가 호소수로 구성되어 있다. 이러한 수자원 이용효율의 취약성으로 인해 제한된 수자원 용량과 생활 및 농공용수의 과수요에 따른 불균형으로 근래 많은 하천이 갈수기나 평수기시 친천화되어 가고 있어 수중생태계에 큰 위협을 주고 있다. 또한 이에 더하여 산업발달과 함께 수질오염원은 양적으로는 물론 질적으로도 증가일로에 있어 기존의 유기 및 중금속 오염물질을 포함해 수많은 신생 유기화합물질이 수계에 유출되고 있으며, 이에 더해 질소 및 인으로 대표되는 영양물질의 유입과다로 국내 대다수의 호수가 부영양화의 새로운 위협에 직 면해 있다. 우리나라에는 적은 유입유량에 큰 저수용량 및 긴 체류시간으로 대표되는 대규모 자연호는 없으며, 대부분이 매단위 강을 막아 형성된 체류시간 1년 이하의 인공호로서 그 중 안동호, 충주호, 대청호 등은 비교적 체류시간이 긴 호소형 인공호로, 팔당호나 기타 대부분의 호수는 체류시간이 짧은 하천형 인공호로 대별된다(Table 1). 이처럼 국내 호소는 국외의 자연 호와는 다른 구조적 특성을 가짐에 따라 부영양화 특성 역시 매우 상이하고, 호소형 인공호와 하천형 인공호간의 차이 역시 현저하여 일률적인 관리대책을 설정하기가 어려운 실정에 있다. 또한 각 호수의 유역특성이 상이함에 따라 호수별로 유역 오염원의 오염부하율이 현저히 달라(Table 2) 호수에 따른 특성적인 유역관리(Lake-specific management)가 요구되고 있다 정상상태(Steady state)가 아닌 국내 호소에 대해 국외 자연호의 인단순모델 (Simple phosphorus budget model)을 그대로 적용하는 것에 다소 무리한 점이 따르나, 평균적인 개념으로 OECD의 유역부하량 및 호소특성에 따른 부영양화 판정모델을 적용한다면, 국내 주요 호수는 모두 부영양 수준에 있다. 또 각 호수별로 부영양화 제어를 위해 요구되는 인의 삭감부하량은 상당량이 되어 현실적으로 관리가 이미 어려운 실정에 와 있다. 호수의 부영양화는 조류 발생으로 이어지며, 그에 따른 폐해는 각종 형태로 나타나는데 대표적으로 이취미 발생이나 유해조류에 의한 독성물질의 배출, 정수처리 과정의 THM 발생등이 주로 문제가 되고 있다. 따라서 국내 호수의 구조적 특성별 부영양화 실태를 파악하고 그에 따른 영향 및 관리방안에 관한 종합적 고찰이 차후 수질관리를 위해 요구되고 있으며, 특히 납조류로 대표되는 유해조류의 독성영향에 관한 연구는 시급한 실정에 있다.