• Korean Journal of Microbiology
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• v.44 no.2
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• pp.147-155
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• 2008

The diversity of sulfate reducing bacteria was investigated in different depths of sediments in Lake Sihwa, Korea and Lake Aha, China by PCR amplification, denaturing gradient gel electrophoresis (DGGE) and clone libraries targeting dissimilatory sulfite redectase (dsr) gene. In the analysis of DGGE band patterns, the community compositions of dsr gene in the sediments of both lakes were significantly different whereas bands in all depths of each environment revealed similar patterns. Bands from Lake Sihwa were produced much more than those from Lake Aha, demonstrating a higher diversity of dsr gene in Lake Sihwa. Total 68 clones containing dsr gene were obtained to analyze their sequences. Sequences from the sediment of Lake Sihwa were affiliated to Deltaproteobacteria, the Gram-positive thermophilic sulfate reducers belonging to the genus Desulforomaculum and archaeal thermophilic SRB belonging to the genus Archaeoglobus, whereas sequences from the sediments of Lake Aha were related to genus Desulfotomaculum. Clones retrieved from sediment of Lake Sihwa revealed a higher numbers than those of Lake Aha, demonstrating a higher diversity of dsr gene in Lake Sihwa. Most of clones (59%) were distantly related to the known cultivated SRB with $60\sim65%$ of similarity, which were clustered only the sequences from the environments showed less than 90% similarity. These habitat specific sequences suggested that the clustered dsr sequences represent species or groups of species that were indigenous to these environments. This study showed that these lakes have a specific bacterial communities having dsr gene distinct from those in other environments such as soil and marine ecosystems around the world.

• Korean Journal of Environmental Biology
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• v.32 no.4
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• pp.371-376
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• 2014

A Study on zooplankton fauna and phytoplankton flora was carried out three times in June, August and September 2012 at the Hyuncheon wetland in Gangwon-do, Korea. A total of 14 taxa of zooplankton were distributed, which consisted of six rotifers, four cladocerans, two copepods, one nematode and one aquatic insect larvae. Occurrence of Simulium japonicum supports that studied water is the first grade clear water. It was observed that the abundance of zooplankton was never exceeded over $55ind.L^{-1}$. Rotifers dominated in the months of June and August, whereas cladocerans in September, respectively. The phytoplankton flora was consisted of 26 species. The standing crops varied between $4,080{\sim}10,120cell.L^{-1}$. Docidium undulatum is the typical species distributed in muddy wetland and Closterium acerosum is distributed widely from wetlands through lakes. Navicula spp. and Nitzchia spp. were recorded to be distributed in lentic waters of big lakes such as Paldang Lake. Species diversity indices decreased gradually from June to September between 1.3~1.9 in zooplankton but lowest in August between 0.9~1.6 in phytoplankton, respectively. Based on my study observation, I anticipate that the poor distribution of zooplankton, phytoplankton, and low values of species diversity index are likely to be a cause of narrow area with shallowness of waters during the short period.

• Journal of the Korean association of regional geographers
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• v.22 no.1
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• pp.211-224
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• 2016

Natural lakes are estimated in variety with that's function or value depending on age environment or geographical characteristics. There are many kind of natural lakes, but the kind of natural lake is limited in rivers in korea flowing into East Sea. However, Yeonho lake in Uljin has different geographical characteristics with oxbow lake or lagoon which is common in korea's river flowing into East Sea. Therefore the purpose of this study is to analyze geographical characteristics due to the process of Yeonho's formation. Further more research for protecting wetland is needed to adequately preserve, depending on the geomorpologic process. To analyze geographical characteristics, it was essential to compare and analyze topographical map of 1918 1956 2012 and I pictured estinated line of bedrock and longitudinal section of Nam-dae cheon(Riv) Yeonho cheon(Riv). In addition, I denoted flooded areas through design flood level of Nam-dae cheon(Riv) Yeonho cheon(Riv) and analyzed particle size distribution of deposited sediment due to consider deposit environment. The results of study are as follows. In conclusion, Yeonho lake is floodbasin which was not researched at river flowing into East Sea. Through this study, my opinion is that floodbasin can be formed in the river that is steep and short. I argue that preservation methods will be seeked by geomorphologic process of floodbasin and development of downtown.

• Korean Journal of Environment and Ecology
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• v.20 no.4
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• pp.365-373
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• 2006

With a few exceptions, Korean lakes are artificially constructed for multi-purposes throughout the country. In the majority of cases, a lake is in a multiple series of reservoirs along a river or is an estuary Moreover, nutrient supplying activities (including sand extraction) and biomanipulation(esp., overfishing and fish introduction) are omnipresent in most cases. Furthermore, there is an Asian monsoon every year. In brief, europhication and algal blooms break out as a result of complicated causes. However limnological monitoring and scientific working programs are in the course of beginning. The question is what kind of strategy is desirable to establish a solid limnological database for the efficiency of the restoration process in each Korean reservoir We present light monitoring cases on the basis of algal and some physicochemical data in 2005. Do they give some useful informations despite their simplicity. Based on physicochemical factors and phytoplankton data using Utermohl method and Canonical Correspondence Analysis(CCA) were performed for Lake Cheongpyeong, Lake ASan, Lake Namyang, and Lake SapGyo. The results of CCA showed that Lake Cheongpyeong was different from the other three Lakes at estuary. Also each Lake at estuary was slightly different from one other. This result would encourage to initiate building an adequate Korean reservoir-ecosystem understanding and models for better ecological management despite the limited data. However, the results also indicate to sustain collecting ecological data and building database to interpret the Korean ecological reservoir model.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.1
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• pp.32-38
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• 2011

In this study, the correlations of concentrations in sediment heavy metals between two pretreatment methods, total digestion and aqua regia digestion, have been investigated. Total 43 samples had been collected from streams and lakes in Yeongsan and Seomjin watersheds. They were decomposed in two pretreatment methods and five metal components (Cd, Cr, Ni, Pb, Zn) were analyzed. Overall average concentrations of heavy metals were Zn>Cr>Pb>Ni>Cd in the order. The concentrations of aqua regia digestion were 35.0% (Cd), 53.8% (Cr), 66.2% (Ni), 64.4% (Pb) and 76.4% (Zn) of the concentrations of total digestion and heavy metal concentrations of total digestion were higher. Heavy metal concentrations in sediments from lakes were higher than those from streams. The correlation equations between the concentrations of total digestion and aqua regia digestion were obtained. The concentrations of Zn and Ni, which showed strong linear correlations, increased in aqua regia digestion as the concentration in total digestion increased. The linear correlation coefficients between two digestion methods for most analyzed metals were above the average correlation. However, these results can be applied with limitations due to heterogeneity of sediments.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.242-252
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• 2009

The purpose of this study was to develop a Multi-metric Water Quality Assessment (MWQA) model and apply it to dataset sampled from Paldang and Daechung reservoir in 2008. The various water dataset used to this study included 5 year data sets (2003${\sim}$2007) in Korean reservoirs which were obtained from the Ministry of Environment, Korea. In this study, suggested MWQA model has 4 metrics that were composed of 4 parameters such as chemical, physical, biological, and hydrological variables. And, each of the variables attributed total phosphorus (TP) concentration in water, secchi depth (SD) measure in water, chlorophyll-${\alpha}$(Chl-${\alpha}$) concentration in water and the ratio of inflow of water into lakes and efflux of water from lakes, input/output (I/O). First, we established the criteria for trophic boundaries. The boundary between oligotrophic and mesotrophic categories was defined by the lower third of the cumulative distribution of the values. The mesotrophic-eutrophic boundary was defined by the upper third of the distribution. Second, each metric was given by a point-oligo=1, meso=3, eu=5. And then, obtained total score from each metric was divided 5 grade-Excellent, Good, Fair, Poor, and Very poor. As the results of applying the proposed MWQA model, the Paldang reservoir obtained "Fair" or "Poor" grade and Daechung reservoir obtained "Excellent" or "Good" grade. The suggested MWQA model through these procedures will enable to manage efficiently the reservoir. And, more studies such as metric numbers and attributes should be done for the accurate application of the new model.

• Korean Journal of Remote Sensing
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• v.15 no.1
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• pp.1-8
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• 1999

The estimation technique of surface water temperature by satellite remote sensing has been applied to ocean and large lakes using AVHRR. However, the spatial resolution AVHBR is not abquate for coastal region and small lakes. Landsat 5 TM has 120 m spatial resolution, which suits better. We carried out analysis of surface water temperature in Lake Sihwa and near coastal area using Landsat 5 TM. To relate digital number to the brightness temperature, we applied Empirical, NASA, RESTEC, Quadratic methods. Comparing calculated and observed value, we obtained as follows; NASA method, $R^2=0.9343$, RMSE(Root Mean Square Error)=3.5876$^{\circ}C$; RESTEC method, $R^2=0.8937$, RMSE=3.76$^{\circ}C$; Quadratic method, $R^2=0.8967$, RMSE=2.949$^{\circ}C$. Because Landsat TM has only one band for extracting surface temperature, it was difficult to correct for the atmospheric errors. For improving the accuracy of surface temperature detection using Landsat TM, there is a need for a method to decrease the effect of atmospheric contents.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.299-310
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• 2018

Odor compounds (geosmin, 2-MIB) have been causing problems in the Bukhan River system, but the causative organisms have not been clearly identified. To evaluate the relationship between dynamics of microbial community and odor compounds, two times monthly monitoring of water quality and microbial community from the three serial lakes (Lake Uiam, Lake Cheongpyeong and Lake Paldang) in the Bukhan River system were conducted from April to October 2017. The odor compounds were analyzed by HS-SPME analysis method using GC/MS. Bacteria communities were identified at the class level by NGS analysis. Actinobacteria and Betaproteobacteria were dominant taxon in bacteria community of three serial lakes. In the case of phytoplankton communities showed that seasonal changes by Bacillariophyceae and Cryptophyceae in spring, Cyanobacteria in summer, and Bacillariophyceae and Cryptophyceae in autumn. Dominant species was Dolichospermum (=Anabaena), Microcystis and Pseudanabaena in Bukhan River system in all study period. At the same time the odors geosmin and 2-MIB were also detected at high concentration. There is a significant positive correlation between proportion of Actinobaceria and 2-MIB concentration (r=0.491, p<0.01). In addition, proportion of cyanobacteria showed a significant correlation of geosmin (r=0.381, p<0.05) and 2-MIB (r=0.386, p<0.05) concentration. In this study, odor compounds in the Bukhan River system are considered to be a direct relationship between with Actinobacteria and cyanobacteria.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.1
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• pp.1-13
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• 2019

The accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) resulted in the deposition of large quantities of radionuclides over parts of eastern Japan. Radioactive contaminants have been observed over a large area including forests, cities, rivers and lakes. Due to the strong adsorption of radioactive cesium by soil particles, radioactive cesium migrates with the eroded soil, follows the surface flow paths, and is delivered downstream of population-rich regions and eventually to coastal areas. In this study, we developed a model to simulate the transport of contaminated sediment in a watershed hydrological system and this model was compared with observation data from eroded soil observation instruments located at the Korea Atomic Energy Research Institute. Two methods were applied to analyze the soil particle size distribution of the collected soil samples, including standardized sieve analysis and image analysis methods. Numerical models were developed to simulate the movement of soil along with actual rainfall considering initial saturation, rainfall infiltration, multilayer and rain splash. In the 2019 study, a numerical model will be used to add rainfall shield effect by trees, evaporation effect and shield effects of surface water. An eroded soil observation instrument has been installed near the Wolsong nuclear power plant since 2018 and observation data are being continuously collected. Based on these observations data, we will develop the numerical model to analyze long-term behavior of radionuclides on land as they move from land to rivers, lakes and coastal areas.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.96-100
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• 2018

Clonorchis sinensis is a main parasite that infects humans by making freshwater fish as an intermediate host in South Korea. There are so many reports about the infestation status of Clonorchis sinensis metacercariae (CsMc) in freshwater fish living in the river, but there are a few studies of fish in the lake. In this study, we examined CsMc in Cyprinid fish sampled from Soyang Lake, Namyang Lake, Andong Lake and Chunchun Lake from 2016 to 2017. Metacercaria of trematodes were found from Hemiculter eigenmanni and Carassius auratus in Namyang Lake, and Zacco platypus and Opsarichthys uncirostris in Soyang Lake. As a result of PCR using Clonorchis sinensis specific primer sets, it was confirmed that the metacercariae from Hemiculter eigenmanni in Namyang Lake was CsMc. This study provides information on CsMc infestation status of Cyprinid fish in four lakes and it is the first report of CsMc infestation in Namyang Lake.