• Korean Journal of Ecology and Environment
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• v.39 no.3 s.117
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• pp.296-309
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• 2006

This study aimed to analyze water quality (temperature, secchi depth, DO, $NH_4$, $NO_3$, $PO_4$, TN, TP, chlorophyll a) and trophic state index during the period of year 2000 ${\sim}$ 2004 in Lake Juam, Lake Dongbok and Lake Youngsan. Lakes Juam and Dongbok except Lake Youngsan were stratified during warm seasons. Water turbidity estimated by secchi disk depth was the highest in Lake Youngsan compared with other lakes. DO concentrations were low in the bottom water when chlorophyll a was high in Lake Juam and Dongbok. Nutrient concentrations were higher in Lake Youngsan than other lakes whereas chlorophyll a was highest in Lake Dongbok. Lake Youngsan was the most eutrophic compared to other two lakes based on the Trophic State Idex (TP) and TSI (SD), The TSI (CHL) was high but the TSI (TP) were low in Lake Juam and Dongbok. These results suggest phytoplankton may be limited by phosphates (P) in Lake Juam and Dongbok whereas light availability in the water column may affect growth of phytoplankton in Lake Youngsan.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.400-408
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• 2013

Total phosphorus was set as a target indicator to prevent eutrophication and algae growth, etc., in three major rivers (Nakdong River, Geum River and Yeongsang/Seomjin River) for the second phase (2011 ~ 2015) in total maximum daily loads (TMDLs) system. However, total phosphorus management was restrictively introduced, i.e., upstream of the Lake Daechung, in the Geum River watershed. Total phosphorus concentration and trophic levels in downstream of the Lake Daechung (include Mangyeong and Dongjin rivers) were increased more than upstream. Therefore, it is necessary to expand total phosphorus management in all watersheds of the Geum River. If total phosphorus was managed in all area of the Geum River watershed, it is possible to decrease total phosphorus concentration and trophic levels, and solve the unbalanced water quality between up and downstream of the Lake Daechung.

• Korean Journal of Ichthyology
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• v.17 no.2
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• pp.131-141
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• 2005

The ichthyofauna and structure of the fish community of Hapcheon Lake on the Hwang River were surveyed at six localities from May 2004 to Feb. 2005. There were 36 species belonging to 31 genera and 12 families in the Hapcheon Lake system. Of these, 24 species (66.7%) were cyprinids; cobitids and centropomids were next with 2 species (5.6%) each. The dominant species in the Hapcheon Lake system was Hemiculter eigenmanni (relative abundance 28.4%), the subdominant species Hemibarbus labeo (24.1%). Ten species (28.3%) of the 36 were Korean endemic species. Among the endemic species, H. eigenmanni and Squalidus chankaensis tsuchigae were abundant at each locality except site 6, but the eight other species were rare. In biomass, H. labeo comprised about 36.5% of the total weight, H. eigenmanni 22.3%, Cyprinus carpio 7.5%, Hypomesus nipponensis 6.9%, Culter brevicauda 3.7% and Lepomis macrochirus 3.6%. Average dominance, diversity, and evenness index of the fish community collected from six localities in the Hapcheon Lake system were 0.21, 0.85, and 0.67, respectively.

• Journal of Korean Society on Water Environment
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• v.25 no.6
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• pp.951-963
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• 2009

The community structure and ecological characteristics of fish community in Lake Paldang were investigated from May to September 2008. During the survey period, 53 species belonging to 13 families were collected. Dominant species was Squalidus japonicus coreanus representing 81.8% of total number and 25.7% of total biomass of collected fish and subdominant species was Lepomis macrochirus representing 3.3% of total number and 18.9% of total biomass of collected fish. There were 20 Korean endemic species (38% of collected species number) including Cottus koreanus and 4 exotic species (7.5%) including Micropterus salmoides. The similarity analysis of fish communities among water areas of Lake Paldang using UPGMA showed that fish community of North-Han River was similar to that of South-Han River area and was different from that of Gyeongan River area. Long-term variation of fish community from 1972 to present study in Lake Paldang showed decrease of the species numbers after dam construction until 1994, and gradual increase from 1996 to present study indicating the disturbance of lentic system by dam construction in the 1980s. The increase of species number in the late 2000s may results in part from the increase of survey sites of successive studies. L. macrochirus which was designated as a domestic ecosystem-disturbing alien species with wide food niche have shown more than 20% of relative abundance since 1996 indicating the adverse effect on not only fish community but also aquatic ecosystem food web of Lake Paldang.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.439-448
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• 2007

The purpose of this study was to investigate the seasonal variations of sediment oxygen demand (SOD) in Lake Paldang and Lake Chungju of the Han River system and to suggest SOD values as parameters for the water quality prediction models of two lakes. SOD was measured at laboratory using sediment collected at 2 sites in Lake Paldang from June to November and at 4 sites in Lake Chungju from May to November in 2005, respectively. It was found from the laboratory test that the SOD in Lake Paldang ranged from 337.8 to 881.0 mg $O_2m^{-2}d^{-1}$ and in Lake Chungju ranged from 143.0 to 969.1 mg $O_2m^{-2}d^{-1}$. The SOD of Lake Paldang showed similar variations to the content of organic matter of sediment. The SOD of Lake Chungju was positively correlated with temperature (r=0.78, p<0.01), $PO_4-P(r=0.79,\;p<0.01)$, TP (r=0.55, p<0.05), DTP (r=0.55, p<0.05), $NO_3-N$ (r=(0.72, p<0.01) of hypolimnetic water. These results indicate that the SOD of Lake Paldang was affected by the content and origin of organic matter of sediment and the SOD of Lake Chungju was closely correlated with physical and chemical factors.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.698-702
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• 2004

At five stations in Gyeongan River, a tributary of Lake Paldang, physicochemical and biological environmental factors of water, particulate matters, and sediments were investigated biweekly from April 11 to December 22 in 2001. The studied area was characterized as a stream-lake system. The system is primarily referred to a place where the environmental factors had considerably changed depending on the amount of precipitation. As a result, the river turned out to be strongly eutrophicated. Also, some characteristics of the water and the particulate matters at midstream such as average concentrations of conductivity, nutrients, and chlorophyll $\alpha$ were higher than the characteristics of up and down-stream. However, the concentrations of organic matters and ratio of clay and silt of the midstream were determined to be higher than up and down-stream sediments. As the result of the factor analysis, 4 major different patterns for environmental factors are found from samples of water, particulate matters, and sediments.

• Journal of Korean Society on Water Environment
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• v.30 no.6
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• pp.665-672
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• 2014

Elemental cellular stoichiometry of natural phytoplankton communities was examined in six large dam reservoirs in the Han River system. Carbon (C) and nitrogen (N) contents of the phytoplankton-dominated seston from Lake Soyang was higher than that from other lakes. Phosphorus (P) content showed slight variations among six lakes in the range of $0.04{\sim}0.18{\mu}mol$ P mg $DW^{-1}$. The phosphorus concentrations of lake water showed obvious positive relationship with P and C contents of the phytoplankton-dominated seston. In all six lakes, N:P ratios and C:P ratios in the phytoplankton-dominated seston were more than 23 and 133 respectively, indicating the phytoplankton communities in six lakes have been exposed in phosphorus limited condition. The relative abundance of diatoms showed significant negative correlation with C, N, P contents of the phytoplankton-dominated seston and that of cyanobacteria showed significant positive correlation. Elemental stoichiometry of diatoms-dominated seston showed distinctive less content than that of cyanobacteria-dominated seston. The cellular N:P ratios of diatoms- and cyanobacteria-dominated seston indicate that both main classes of phytoplankton in six lakes are in phosphorus deficiency. Elemental stoichiometry of the phytoplankton-dominated seston in this study could be used for the further ecological stoichiometric studies in six lakes.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1387-1391
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• 2007

In this study, water quality prediction that is necessary to water quality forecasting system is performed using 2-D river analysis models RMA-2 and RAM4. RAM4 is suitable to water quality forecasting system cause it is possible to put in the pollutants as a mass type boundary condition. Instant injections of pollutants at Yongdamdaegyo Bridge in Namhangang River are simulated and the behavior of pollutant cloud is observed. The effects of water quality accident to Paldang 2 water intake plants in Paldangho Lake is analyzed with time variation. And extra flow simulation is performed for mitigation of pollution. Several cases of water quality forecasting system at home and abroad are investigated and the direction of water quality forecasting system is presented.

• Korean Journal of Environmental Biology
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• v.41 no.2
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• pp.101-108
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• 2023

Recently, in relation to climate change, many studies have been conducted to predict the potential habitat area and distribution range of tilapia and the suitability of habitat for each species. Most tilapia are tropical fish that cannot survive at water temperatures below 10 to 12℃, although some tilapia can survive at 6 to 8℃. This study predicted habitable areas and the possibility of spreading of habitat ranges of tilapia (Oreochromis niloticus and Oreochromis aureus) known to inhabit domestic streams. Due to climate change, it was found that habitats in the Geum River, Mangyeong River, Dongjin River, Seomjin River, Taehwa River, Hyeongsan River, and the flowing in East Sea were possible by 2050. In addition, it was confirmed that tilapia could inhabit the preferred lentic ecosystem such as Tamjin Lake, Naju Lake, Juam Lake, Sangsa Lake, Jinyang Lake, Junam Reservoir, and Hoedong Reservoir. In particular, in the case of tilapia, which lives in tributaries of the Geumho River, Dalseo Stream, and the Nakdong River, its range of habitat is expected to expand to the middle and lower of the Nakdong River system. Therefore, it is judged that it is necessary to prepare physical and institutional management measures to prevent the spread of the local population where tilapia currently inhabits and to prevent introduction to new habitats.