• Analytical Science and Technology
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• v.24 no.4
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• pp.304-309
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• 2011

In this research, behaviour of turbidity and phosphorus in water and soil dependent upon pH and a change of water was studied. Phosphorus dissolve rate from turbidity was increased for water if potential of hydrogen was less than pH 4 or more than pH 7. Turbidity release rate from soil was increased with pH. Turbidity release rate from soil was drastically increased for water if potential of hydrogen was more than pH 4. turbidity release rate from soil was stabilized more than pH 6. Dissolved phosphorus was increased from 2 hours to 24 hours and stabilized in 24 hours. Turbidity was reached the peak of 24 hours and decreased from 24 hours to 96 hours. Turbidity and dissolved phosphorus was decreased for water if these samples were changed a overlying water. Behaviour of turbidity was analogous to dissolved phosphorus when potential of hydrogen was increased from pH 6 to pH 10 and a change of overlying water was increased from 1 time to 4 times. These results suggest that phosphorus dissolve rate and turbidity were directiy correlated with pH. These results are of great importance in lakes because most lakes have a pH in the range of pH 7-10.

• Journal of the Korean Institute of Landscape Architecture
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• v.37 no.1
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• pp.50-64
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• 2009

The freshwater lakes located at the fringe of urban cities are a habitat for diverse organisms. However, they are facing severe danger of environment deterioration and water pollution caused by reckless development of the area. In this study, an ecological management plan was suggested to promote the biodiversity through appointing management area based on the research and analysis data of flora and fauna as well as maintain biodiversity and harmonize utilization of freshwater lakes such as Duryang Reservoir at Sacheon, Gyeongsangnam-do. Base on the data of ecological research and analysis, this study conducted research on biotope assessment, wild life habitat assessment and presence of protected species. As a result, the ecosystem conservation area including multi-layer structured natural forests, waterside and wetland that are home to various species and the edge area with high habitat diversity were recognized as highly preservable regions. Management areas were ecologically disturbed region, highly polluted commercial district and damaged waterside caused by fishing. Proactive management must be implemented through vegetation management such as vegetation transition and shrub planting as well as establishing pollutant management system. The deterioration of waterside and forest vegetation of freshwater lake has a direct influence on biodiversity and water quality. Therefore, the conservation area and development area should be totally separated from each other, and the development area must be restored and managed strictly.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.141-152
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• 2001

Abundance of autotrophic picoplankton (APP) and their contribution to phytoplankton biomass were assessed in seven brackish lagoons and five freshwater reservoirs in the summer season. Phycocyanin-rich picocyanobacteria dominated APP in lagoons, while phycoerythrin-rich picocyanobacteria dominated APP in freshwater reservoirs. The cell density of APP ranged from $3.6{\times}10^3$ to $5.0{\times}10^6\;cells/ml$ (median $2.5{\times}10^5$) in brackish lagoons and from $3.8{\times}10^4$ to $3.6{\times}10^5\;cells/ml$ (mdian $1.3{\times}10^5$) in reservoirs. Carbon biomass ranged from 1.0 to $1,385.0\;{\mu}gC/L$ in lagoons and from 15.3 to $128.2\;{\mu}gC/L$ in reservoirs. APP cell density in Lake Kyungpo was over $10^6\;cells/ml$in all three surveys, which is one of the highest values recorded in all over the world. During the thermal stratification in Lake Soyang, the maximum abundance of APP and their maximum contribution to phytoplankton biomass were observed near the thermocline. This study showed that APP sometimes can contribute significantly to phytoplankton biomass both in lagoons and reservoirs with the range from 0.1 to 85.0%. APP which have been overlooked in the past studies appears to be important primary producers in Korean lake ecosystem.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.304-310
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• 2003

This study was conducted to estimate the internal dissolved organic carbon (DOC) loading from sediment in eutrophic shallow Lake Kasumigaura. Contents of water and organic carbon were about 80% and 6.3% with depth in the sediment, respectively. The highest DOC concentration in porewater (104 mg C/l) was observed in September suggesting that the porewater could play an important role as an internal loading of DOC. Results of DOC release experiments showed that the labile-DOC (L-DOC) release was not detected in the oxic condition, while refractory-DOC(R-DOC) release was detected. The L-DOC and R-DOC release rates in the anoxic codition ranged from 14.5${\sim}$ 48.6, 14.4 ${\sim}$27.3 mgC $m^{-2}$ $d^{-2}$, respectively. The current study showed that L-DOC released in the oxic condition was rapidly utilized by aerobic bacteria, in contrast, L-DOC and R-DOC released in anoxic codition were slowly utilized by anaerobic bacteria. These results suggested that L-DOC and R-DOC were closely related to sediment release and most of the R-DOC released could be an important source of DOC in eutrophic lakes during summer. Therefore, R-DOC pool should be added as one of the important energy source for microbial-based aquatic food webs in eutrophic lakes.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.342-349
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• 2000

This paper demonstrates the influence of intensity of the monsoon on morpho-hydrological fluctuations in Taechung Reservoir during 1993${\sim}$1994. During the study, hydrological variables including rainfall, inflow, and discharge volume showed distinct contrast between 1993 and 1994. Interannaul differences in rainfall occurred during the monsoon in July${\sim}$August monsoon and influenced inflow, discharge, and water residence time (WRT). Total inflow in 1993 was four times greater than that of 1994, and summer inflow in 1993 was 8 times greater than summer 1994. Annual Mean WRT was 93.2 d in 1993 vs. 158.6 d in 1994 and the largest differences occurred between monsoons of 1993 and 1994. Morphometric variables reflected the interannual contrasts of hydrology, so that in 1993 surface area, total volume, shoreline development, and mean depth increased consistently from premonsoon to postmonsoon and over this same period in 1994 they decreased. This outcome indicates that the area of shallow littoral zones in 1993 was greater than in 1994. Also, the drainage area to surface area (D/L) at 80 m MSL was 60.7 which was much greater than values in Soyang and Andong reservoirs and natural lakes world-wide. The morpho-hydrodynamic conditions seemed to influence in-reservoir nutrient concentration which is one of the most important factors regulating the eutrophication processes. I believe, under the maximum hydrodynamic fluctuations in Korean waterbodies during the monsoon, applications of mass balance models to man-made lakes for assessments of external loading should be considered because the models can be used under the seasonally stable inflow and water residence time.

• The Korean Journal of Quaternary Research
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• v.24 no.1
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• pp.11-24
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• 2010

Seongnyu Cave have developed along the NE-SW direction in carbonate rocks of the Joseon Supergroup. The cave mostly shows horizontal passages and contains three lakes. The main passage is about 330 m long with 540 m-long branches, thus the total length of the cave is about 870 m. Through cave diving, about 85 m-long new passages were discovered. Numerous speleothems such as soda straws, stalactites, stalagmites, columns, flowstones, rimstones, cave shields, cave corals, curtains (and bacon sheets), cave pearls, cave flowers, helictites and calcite rafts can be found in the cave. Especially, some speleothems which were believed to have grown in the past were discovered in the submerged passage, and a few stalactites, stalagmites, flowstones and columns were eroded (or corroded) by the cave stream that flowed on the floor. Because these speleothems only grow in subaerial environments within limestone caves, it appears that they grew when there was no lake in the cave and became submerged as the lake level rose in the cave. The presence of these speleothems in the lakes indicate that they only grew during glacial periods when sea-level was lower. Therefore, detailed investigation of these speleothems will provide invaluable information on paleoclimatic evolution around the Korean peninsula in the future.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.11
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• pp.781-790
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• 2014

Contaminants such as organic matters, nutrients and toxic chemicals in rivers and lakes with a weak flow rate are first removed from the water and accumulated in the sediments. Subsequently, they are released into the water column again, posing direct/indirect adverse effects on the water quality and aquatic ecosystems. In particular, phosphorus is known to accelerate the eutrophication phenomenon when it is released into the water column via physical disturbance and biological/chemical actions as one of important materials that determine the primary production of aquatic ecosystems and an element that is stored mainly in the sediments in the process of material circulation in the body of water. In this study, the effect on reducing phosphorus release in sediments was analyzed by applying different capping materials to lake water, where the effect of aquatic microorganisms is taken into account, and to distilled water, where the effect of microorganisms is excluded. The experimental results showed that capping with chemical materials such as Fe-gypsum and $SiO_2$-gypsum further reduced the phosphorus release by at least 40% compared to the control case. Composite materials like granule gypsum+Sand showed over 50% phosphorus release reduction effect. Therefore, it is determined that capping with chemical materials such as granule-gypsum and eco-friendly materials such as sand is effective in reducing phosphorus release. The changes in phosphorus properties in the sediments before and after capping treatment showed that gypsum input helped to change the phosphorus that is present in lake sediments into apatite-P, a stable form that makes phosphorus release difficult. Based on the above results, it is expected that the application of capping technology will contribute to improving the efficiency of reducing phosphorus release that occurs in river and lake sediments.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.27-34
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• 1999

In order to obtain necessary data for the use of hydrophytes to improve water quality of artificial lakes, production and nutrients absorption by some macrohydrophytes were investigated in a small water course at Woongcheon, Chungnam Province. The maximum above-ground standing biomass of Phragmites communis, Typha angustifolia and Zizania latifolia stand were 3,504 g/m$x^2$, 2,834 g/m$x^2$ and 3,125 g/m$x^2$, respectively. Estimated below-ground standing biomass of each stand were 9,671 g/m$x^2$,5,158 g/m$x^2$ and 5,813 g/m$x^2$, respectively. Concentration of nutrients in each organ was different among plant species. Maximum amount of standing nitrogen was the highest in the reed stand and that of standing phosphorus was the highest in the cattail stand. Amount of maximum standing nutrients are 2795.6 kgN/ha and 42.5 kgP/ha for the reed stand, 1,413 kg N/ha and 24.8 kgP/ha for the cattail stand and 1.901.1 kgN/ha and 38.4 kgP/ha for the wild rice stand, respectively. According to our investigation, it is concluded that reed, cattail and wild rice are suitable for water quality improvement of artificial lakes through nutrients absorption.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.197-205
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• 2000

Factors most strongly related to zooplankton growth rates were studied along a lake and a river stretch in the middle part of the lowland River Spree. The study was conducted at the lake inflow (S1), the lake outflow (S2), and at the end of a 21 km stretch of the outflow (S3) from March to November of 1999. Total zooplankton biomass increased significantly at S2 and then sharply decreased at S3. The abundance of microzooplankton (rotifers and nauplii) was strongly higher than macrozooplankton (cladocerans and copepodids) at all station. However, macrozooplankton biomass (${\mu}$g dw 1$^{-1}$) was similar or much higher than microzooplankton biomass. Large-bodied cladocerans (Daphnia cucullata) dominated at S2 while small-bodied cladocerans (Bosmina longirostris) dominated at S1 and S3. Patterns in growth rates (r$_{t}$ in d$^{-1}$ of the major zooplankton community were greatly different between S1 and S2 (lake stretch) and between S2 and S3 (river stretch). In the lake, growth rates generally were positive, while values of growth rates were negative in the river stretch. Among the environmental variables considered, partial retention time (PRT, d$^{-1}$) seemed to play the most important role in determining characteristics of the zooplankton community structure in the middle part of River Spree.

• Korean Journal of Ecology and Environment
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• v.48 no.4
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• pp.263-271
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• 2015

To evaluate the relationship between dynamics of cyanobacteria and odorous compounds, a monthly monitoring of water quality and phytoplankton were conducted at the three serial lakes (Lake Ui-am, Lake Cheong-pyeong and Lake Pal-dang) in the North Han River for 11 times from May 2014 to March 2015. In the three serial lakes, phytoplankton communities showed that seasonal changes in Bacillariophyceae-Cyanophyceae-Bacillariophyceae. Anabaena and Pseudanabaena were dominant species in August and September 2014. At the same time the odors (Geosmin, 2-MIB) were also detected with high concentration. Relationship between environmental factors and cyanobacterial abundance showed a significant correlation with Anabaena circinalis and geosmin (r=0.983, p<0.01). In the case of Pseudanabaena limnetica showed a significant correlation of total nitrogen (r=0.685, p<0.01) and NO3-N (r=0.723, p<0.01). In addition, similarly Pseudanabaena limnetica and 2-MIB (r=0.717, p<0.01) was high. The odorous compounds appeared in the North Han River water were considered to be a direct relationship with cyanobacteria.