• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.195-205
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• 1988

Distribution of organic materials In the surface sediments was investigated in September 1983 in Chinhae Bay System. Bottom waters containing less than 1ml/l of dissolved oxygen were found in Masan Bay, and in part of Kohyonsong Bay and Wonmunpo Bay. Organic carbon content in the surface sediments of Masan Bay was about 25mg/g and it decreased with increasing distance from the inner Masan Bay. Mean organic carbon contents in Wonmunpo Bay and Kohyonsong Bay were 25.48 and 31.39mg/g, respectively, which are higher values than those in Masan Bay where large amount of domestic and industrial wastewaters art discharged into the surface water and extensive phytoplankton occurs almost year round. Mean organic nitrogen and pheophyton contents were also the highest in Kohyonsong Bay amont eight subareas. In Masan Bay, settling of organic materials on the surface sediments seemed to be not significant because of active tidal mixing and relatively small size of particulate materials. In Kohyonsong Bay and Wonmunpo Bay large fecal pellets produced in shellfish farms could be easily settled down on the sediment because of weak current regime. DO content in the bottom waters were low in the organic material rich areas, and that suggests biodegradation of organic materials in the surface sediments could be an important oxygen consuming process during the study period of September 1983.

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.646-656
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• 2012

This study area was Saemangeum Reservoir in Korea and the applied model was Environmental Fluid Dynamics Code(EFDC). It was the same as the scenarios to the boundary and initial conditions except the resolutions of the model grids. The resolutions were about 800 and 2,000 cells. It was considered scenario 1 and 2. The model was performed to simulate the water temperature, salinity, water quality parameters such as dissolved oxygen(DO), chemical oxygen demand(COD), total nitrogen(T-N), and total phosphorus(T-P) at 2008. The simulation results of the two scenarios were reflected in the trend of observed data tolerably. However, water flow, water temperature, and salinity showed high confidence level at the scenario 1. The water quality items did not present high confidence level at the scenario 1 because which concept was considered to biochemical and physical processes. This result shows that grid resolution has an influence on the water transport and the effect is reflected directly shallow and narrow water area. But, the selection of grid resolution should be considered the purpose of model simulation and the process of target items.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.239-244
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• 2013

Mass mortalities of farmed shellfish, mostly in summer season, thus named mass summer mortalities, have been a global issue in shellfish aquaculture. The 2013 mass summer mortalities in the confined waters of Goseong Bay, Goseong, Korea were quite a unique and intensive for two farmed species, the Pacific oysters, Crassostrea gigas, and bay scallops, Argopecten irradians. The mortalities were progressive from the bottom of the suspended oysters and caged scallops in the waters, reaching up to 80% for the oyster and 95% for the scallop in about 20 days after the first occurrence, early August, 2013. We monitored a wide range of environmental factors, including water temperature, dissolved oxygen (DO), salinity, turbidity, acidity (pH), organic and inorganic matters, chemical oxygen demand (COD), suspected pathogenic agent, and phytoplankton composition throughout the water column where the two species were suspended or caged. Our survey concluded that the hypoxia or anoxia might be a major cause of the mortalities. Here, we detailed the mortalities and ways to arrive at the conclusion.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.6
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• pp.89-100
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• 2021

The conservation of stream habitats has been gaining more public attention and fish habitat suitability index (HSI) is an important measure for ecological stream habitat assessment. The fish habitat preference is affected not only by physical stream conditions but also by water quality of which HSI was not available due to the lack of field data. The purpose of this study is to estimate the HSI of Zacco platypus for water quality parameters of water temperature, dissolved oxygen (DO), and biochemical oxygen demand (BOD) using the water environment monitoring data provided by the Ministry of Environment (ME). Fish population data merged with water quality were constructed by spatio-temporal matching of nationwide water quality monitoring data with bio-monitoring data of the ME. Two types of the HSI were calculated by the Instream Flow and Aquatic Systems Group (IFASG) method and probability distribution (Weibull) fitting for the four major river basins. Both the HSIs by the IFASG and Weibull fitting appeared to represent the overall distribution and magnitude of fish population and this can be used in stream fish habitat evaluation considering water quality.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.3
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• pp.160-168
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• 2003

This study was carried out to investigate the effects of induced wet-injury conditions on barley seedling growth. Barley seedlings at the three leaf stage were grown in culture solutions with various combinations of dissolved oxygen (DO), nutrients and citric acid (CA) concentrations. Seedling growth was reduced by hypoxia. Root length and root fresh weight were most severely reduced under 1 ppm DO. Shoot growth was slightly reduced but not root growth under low nutrient condition. Seedling growth was reduced by CA in a concentration-dependant manner, Response of seedling growth was efficiently differentiated in a solution containing 1 ppm DO, one tenth of the normal P, K and Mg concentration and 3 mM CA. Under this induced wet-injury condition, overall seedling growth of 6 cultivars was reduced by 11 to 19% compared to the control condition. The results suggest that the induced wet-injury condition can be used for the screening of resistant genotypes at the seedling stage.

• Journal of Environmental Science International
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• v.24 no.11
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• pp.1485-1491
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• 2015

There are two treatment processes that are currently applied to ships are the biological treatment process using the activated sludge and the electrochemical treatment. However, neither of them are able to remove both nitrogen and phosphorus due to their limited ability to remove organic matters, which are main causes of the red tide. This study was conducted to identify the characteristics of nitrogen removal factors from manure wastewater by replacing the final settling tank in SBR (Sequencing Batch Reactor) process and applying immersion type hollow fiber membrane. SBR process is known to have an advantage of the least land requirement in special environment such as in ship and the immersion type hollow fiber membrane is more stable in water quality change. As the result, the average in the cases of DO (Dissolved Oxygen) is 2.9(0. 6~3.9) mg/L which was determined to be the denitrifying microorganism activity in anaerobic conditions. The average in the cases of ORP (Oxidation Reduction Potential) is 98.4~237.3 mV which was determined to be the termination of nitrification since the inflection point was formed on the ORP curve due to decrease in the stirring treatment after the aeration, same as in the cases of DO. Little or no variation in the pH was determined to have positive effect on the nitrification. T-N (Total Nitrigen) removal efficiencies of the finally treated water were 71.4%, 72.3% and 66.5% in relatively average figures, thus was not a distinct prominence. In being applied in ships in the future, the operating conditions and structure improvements are deemed necessary since the MEPC (Marine Environment Protection Committee). 227(64) ship sewage nitrogen is less than the standard of 20 Qi/Qe mg/L or the removal rate of 70%.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.166-170
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• 2011

Modem people have begun to have the nationwide interest in the rice wine called Makgeolri which is one of the traditional Korean alcoholic liquors. This study was performed to investigate the effects of San sung Makgeolri extract (SM) on antioxidation together with the determination of pH and dissolved oxygen (DO) in the progress of fermentation in the lipopolysaccharide(LPS)-treated rats. We examined the levels of SOD (superoxide dismutase), CAT (catalase), GPx (glutathione peroxidase) in liver homogenates and the histopathological observations in liver tissue. LPS-treated group markedly decreased the levels of SOD, CAT and GPx. But SM + LPS-treated group significantly increased the levels of them. Furthermore, the antioxidative effects of SM were supported by the histopathological observations in liver tissue which showed severe inflammation and necrosis in LPS-treated group, compared to the attenuated inflammation and necrosis in SM + LPS-treated group. This results suggested that SM could be a candidate of antioxidative material in spite of alcoholic liquors.

• Journal of Aquaculture
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• v.13 no.1
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• pp.39-46
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• 2000

Successive management of prawn farm is strongly dependent upon monitoring of pond seawater quality which is generally influenced by an excessive food supplied sediment type and phytoplankton composition in the pond. For good condition of seawater quality it must need exchangning of fresh seawater by tidal current. Two distinct shrimp ponds Galha and Yunho which were different in seawater exchanging system and sediment type were selected to understand how some factors affected to seawater and sediment qualities in the pond. Prawn growth was also determined. Galha pond characterized by sand bottom with water exchanging by turn of the tidal current accumulated 1.8 mgS/g-dry as sulfide in sediment while Yunho pond mud- bottomed with seawater exchanging of pumping system showed 4.7mgS/g-dry when it was highest, Ammonia-N and hydrogen sulfide measured in the seawater were 0.31mg/${\ell}$ and 21.2 ${\mu}$${\ell}$/${\ell}$in Yunho and 0.10mg/${\ell}$and 10.8${\mu}$${\ell}$/${\ell}$in Galha pond respectively. Dissolved oxygen remained below 6.0mg/${\ell}$ in Galha and 5.0mg/${\ell}$in Yunho pond from June through August. Less growth of prawn was found in Yunho pond than in Galha pond. Prawn growth expressed as body length and weight were 138.3mm 22.9g in Yunho pond while they were length 158.2mm and 28.9g in Galha pond respectively when they were harvested in October. These results indicate that higher levels of ammonia-N and hydrogen sulfide and lower dissolved oxygen in bottom seawater of Yunho pond might affect the growth of cultured prawn.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.289-300
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• 2013

In this study, two types of wetland plants, Eichhornia crassipes (a floating plant) and Ceratophyllum demersum (a submerged plant) were introduced to wetland mesocosms to understand how the water properties of wetlands such as pH, dissolved oxygen content, water temperature, oxidation reduction potential, and nutrient concentrations are affected by different types of wetland plant. The floating plant lives on the water surface and can block light penetration; it exhibited the lowest water temperature and temperature difference between lower and upper layers. After the addition of contaminants, the dissolved oxygen (DO) concentration decreased abruptly but recovered continuously in all mesocosms; especially the submerged plants, which photosynthesize in water, showed the largest increases in DO and diel periodicity DO, as well as in pH value. The oxidation-reduction potential in both water and sediment were affected by the presence of wetland plants and plant type and the results suggest that various aspects of wetland biogeochemistry are affected by the presence and type of wetland plants. The total nitrogen and phosphorous concentrations in water decreased in the following order: Water only < Water + Soil < Floating Plants < Submerged Plants. Although both floating and submerged plants can control algal concentrations, the effect was more prominent for floating plants.

• Korean Journal of Environmental Agriculture
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• v.42 no.1
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• pp.52-62
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• 2023

This study focused on determining the specific causes and prevention methods of mass fish deaths occurred in five reservoirs (Gagugi, Neupgokgi, Danggokgi, Sagokji, and Hangokji) in Andong-si. For this purpose, a survey of agricultural land and livestock in the upper part of the reservoirs and analysis of water quality in the reservoir irrespective of whether it rains or not were conducted. We attempted to examine the changes in dissolved oxygen (DO) in the surface and bottom layers of reservoirs and changes in DO depending on the amount of livestock compost and time. Based on the above investigations, treatment plans were established to efficiently control the inflow of contaminated water into reservoirs. The rainfall and farmland areas in the upper part of the reservoir were investigated using Google and aviation data provided by the Ministry of Land, Infrastructure, and Transport. The current status of livestock farms distributed around the reservoirs was also examined because compost from these farms can flow into the reservoir when it rains. Various water quality parameters, such as phosphate phosphorus (PO₄-P) and ammonium nitrogen (NH₃-N), were analyzed and compared for each reservoir during the rainy season. Changes in the DO concentration and electrical conductivity (EC) were also observed at the inlet of the reservoir during raining using an automated instrument. In addition, DO was measured until the concentration reached 0 ppm in 10 min by adding livestock compost at various concentrations (0.05%, 0.1%, 0.3%, and 0.5% by wt.), where the concentration of the livestock compost represents the relative weight of rainwater. The DO concentration in the surface layer of reservoirs was 3.7 to 5.3 ppm, which is sufficient for fish survival. However, the fish could not survive at the bottom layer with DO concentration of 0.0-2.1 ppm. When the livestock compost was 0.3%, DO required 10-19 h to reach 0 ppm. Considering these results, it was confirmed that the DO in the bottom layer of the reservoir could easily change to an anaerobic state within 24 h when the livestock compost in the rainwater exceeds 0.3%. The results show that the direct cause of fish mortality is the inflow of excessive livestock compost into reservoirs during the first rainfall in spring. All the surveyed reservoirs had relatively good topographical features for the inflow of compost generated from livestock farms. This keeps the bottom layer of the reservoir free of oxygen. Therefore, to prevent fish death due to insufficient DO in the reservoir, measures should be undertaken to limit the amount of livestock compost flowing into the reservoir within 0.3%, which has been experimentally determined. As a basic countermeasure, minerals such as limestone, dolomite, and magnesia containing calcium and magnesium should be added to the compost of livestock farms around the reservoir. These minerals have excellent pollutant removal capabilities when sprayed onto the compost. In addition, measures should be taken to prevent fish death according to the characteristics of each reservoir.