• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.735-749
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• 2018

In this study, one studied the principal factors and water-quality components that determine the concentration of chemical oxygen demand (COD) in seawater in estuaries, such as the Han, Geum, Youngsan, Seomjin, and Nakdong rivers in Korea. The principal factors determining the concentration of COD in seawater indicated by the principal component analysis were salinity, exogenous origin and autochthonous resources based on chlorophyll-a. Moreover, organic matter in the submarine sediment layer also had a secondary effect. Regression slope assessed the contribution of water-quality components to determine the concentration of COD in the estuary. One found that the effect of salinity on the overall survey was significant. Moreover, the effect of chlorophyll-a was also appeared in April and August. In each estuary, the most significant contribution factor was chlorophyll-a in the Nakdong River and salinity in the Han and Yongsan rivers. The contribution of salinity and chlorophyll-a were found to be the largest in the Geum River. The salinity and chlorophyll-a in the Seomjin River showed a low contribution.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.2 s.29
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• pp.119-125
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• 2007

In order to illustrate the variation cf stratification and to know the effects of the temperature and the salinity on the stratification in the South Sea of Korea, the stratification parameter defined as potential energy anomaly (PEA, $V(J/m^3)$) introduced by Simpson and Hunter (1974) was used. The oceanographic data were obtained in August 1999 and February 2000 by National Fisheries Research and Development Institute (NFRDI). V in August is generally high in offshore and low in near shore. However, in February, V in the near shore is higher than that cf the offshore due to the vertical temperature gradient between surface and bottom layer caused by the expansion of South Korean Coastal Waters (SKCW). In summer, the increase of the atmospheric heating acts on the stratification as the buoyancy forcing. In most cases, the effect cf the temperature on the stratification is stronger than that of the salinity. The temperature effect is predominantly due to the extent of the intrusion of Tsushima Warm Current into the study area. However, at stations where V is high the effect of the salinity is also significant. In winter, V is very low due to the decrease cf the buoyancy forcing, but some stations show the relatively high V due to the expansion of SKCW and salinity in winter unlike that in summer makes the stratification weak.

• Proceedings of KOSOMES biannual meeting
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• 2003.11a
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• pp.181-185
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• 2003

the effect if atmosphere is more important in the West sea of Korea than in other seas because of shallow water and heat storage if the water. The serial oceanographic observation data and coastal station data from NFRID, and the atmosphere data from KMA were used in order to find out the relationship between them The highest water temperature, salinity and weather factor were recorded in Aug, and the lowest of them in Feb. As the water deepens, the maximum time leg in water temperature and the minimum time leg in salinity. Water temperature have the maximum in Oct, the minimum in Apr at 75m of the 311-07 station with 100m depth water temperature (WT)-air temperature, WT-precipitation (Preci.) and salinity (Sal)-wind speed (WS) were in direct proportion, but WT-WS, Sal-AT and Sal-Preci in inverse proportion Water temperature and salinity I-ave time leg at the same depth the maximum had more the delay of $2\~4$ months at a depth if 20 meters than at the surface in all stations except for salinity at 307-05.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.1
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• pp.69-73
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• 1976

Mortality of clam, Meretrix lusoria was measured during the experimental cultures in different sediments compositions and in different salinities of sea water. Experimental groups maintained in silt and clay showed significant mortality, while those treated in sand and in sand-silt showed little mortality. In the groups cultured in silt and clay, young groups of approximately 2.5cm in shell length were subjected to early and high mortality (approximately eighty-five per cent in foully-one days). The larger the shell size was, the later and the lower the mortality occurred. In different salinity, the groups maintained in silt and clay showed different mortalities. It is observed that the survival rate of the shell in the sea water of low salinity was higher than that in the high salinity water. Oxygen consumption of isolated gill tissue showed a little difference between the groups maintained in silt and clay and those in sand (the control-group). Consequently, it may be stated that the mortality results mainly from the deposition of silt and clay, although the survival rate of Meretrix lusoria depends also on water temperature, salinity, dissolved oxygen, body size ana other factors.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2003.10b
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• pp.43-43
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• 2003

Multiple regression equations (Rehman et al. 2000) have been developed to predict the salinity tolerance of Acacia seeds, expressed as the I$\sub$50/ (the concentration of NaCl required to reduce final germination to 50% of the control value in DW). Accurate predictions can be made using one or more chemical and biological seed parameters. In this study the theoretical effect of varying final germination percentage in distilled water, germination rate in distilled water. (Rate), Ca$\^$2+/ or K$\^$+/ contents and their ratios, as independent factors or related factors, on the predicted salinity tolerance (I$\sub$50/) of Acacia species was investigated. Simulation of the effects of changing final germination, rate, calcium and potassium suggest the possibility of practical application of these results to modify the salinity tolerance of seeds. The predicted I$\sub$50/ increased with increasing final germination. Similarly, the higher the rate of germination, the higher the predicted salt tolerance of Acacia species. The Ca$\^$2+/ content of seeds was found to be positively correlated with I$\sub$50/. Species with higher Ca$\^$2+/ contents had a higher I$\sub$50/. This suggests that I$\sub$50/ might be increased by increasing the Ca$\^$2+/ contents of seeds by pretreatment with calcium salts or by supplying these to the mother plants.

• Journal of Aquaculture
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• v.9 no.4
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• pp.321-327
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• 1996

Production of resting egg from the Korean rotifer, Brachiunus plicatilis (L and S-type) was investigated at different temperatures (L-type : 20, 24, $28^{\circ}C$, S-type : 28 32, $36^{\circ}C$) and salinities (10, 20,30 ppt). The rotifer was cultured in 25 ml test tube and fed on Nannochloris oculata. With regard to mixis rate, L-type rotifer showed higher rate at lower temperature, and the highest rate was observed at 20 ppt of salinity at each temperature of the experiment. However, for S-type rotifer, the optimum temperature and salinity were $28\~32^{\circ}C$ and 20 ppt, respectively. The highest number of resting egg was 173 eggs/ml in 16 days at $24^{\circ}C$, 10 ppt for L-type rotifer and 410 eggs/ml in 14 days at $28^{\circ}C$, 10 ppt for S-type rotifer. The maximum number of resting egg produced per 10,000 rotifers was 8,122 eggs at $20^{\circ}C$, 20 ppt for L-type rotifer and 8,700 eggs at $28^{\circ}C$, 20 ppt for S-type rotifer. The maximum number of resting egg produced $10^8$ cells of N. oculata was 50.7 eggs for L-type rotifer ($24^{\circ}C$, 20 ppt) and 79.6 eggs for S-type rotifer ($32^{\circ}C$, 10 ppt). The number of resting egg produced per day was $1\~11$ eggs/ml for L-type rotifers and $21\~35$ eggs/ml for S-type rotifer in 9 combination experiments. In this study, S-type rotifer is better than L-type rotifer in resting egg production, and the optimum temperature and salinity for resting egg production were $20^{\circ}C$, 20 ppt for L-type rotifer and $28^{\circ}C$, 20 ppt for S-type rotifer. This result shows the difference of Korean rotifer in the optimum condition for resting egg production from other rotifers reported earlier.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.209-215
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• 1999

Changes of malate dehydrogenase isozyme in oyster exposed to different temperature, pH and salinity were investigated by polyacrylamide gel electrophoresis. MDH isozyme in control group was separated into two bands on the positive side. In case of temperature and pH stress, MDH isozyme was separated into only one band after 12 hours exposure but two bands after 24, 48 hours exposure on the positive side. In case of salinity stress, after 12 hours exposure, MDH isozyme bands were separated into two bands in 5 ppt, 30 ppt and three bands in 10 ppt, 40 ppt concentration on the positive side. After 24 hours and 48 hours exposure case in salinity stress, MDH isozyme bands was separated into two bands on the positive side in all concentration. Activities of isozyme bands show their characteristics according to the condition of experiment. In conclusion, changes of MDH isozyme was a biochemical defense mechanism in oyster and result from effect of environmental stress to oyster.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1475-1486
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• 2008

Bentonite-based grouting has been popularly used to seal a borehole installed for a closed-loop vertical ground heat exchanger in a geothermal heat pump system (GHP) because its high swelling potential. However, if the bentonite-based grouting is conducted in coastal areas, the salinity of groundwater changes in the mineral fabric of bentontie. In order words, an increase of cation concentration in groundwater leads to a reduction in the diffuse double-layer thickness in the bentonite mineral structure, and thus the volume of bentointe-based grouts will decrease proportional to the salinity of groundwater. In this paper, the effect of salinity (i.e., NaCl 0.5M, 0.25M, and 0.1M) on the change of swelling potential for bentonite-based grouts has been quantitatively evaluated for seven bentonite grouts from different product sources. In addition, in case of using addictives such as a silica sand to increase the thermal conductivity of bentonite-based grouts, the possibility of particle segregation has been studied considering the viscosity of grouts and salinity of groundwater.

• The Plant Pathology Journal
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• v.37 no.6
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• pp.662-672
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• 2021

Plant growth-promoting bacteria improve plant growth under abiotic stress conditions. However, their effects on microbial succession in the rhizosphere are poorly understood. In this study, the inoculants of Bacillus mesonae strain H20-5 were administered to tomato plants grown in soils with different salinity levels (EC of 2, 4, and 6 dS/m). The bacterial communities in the bulk and rhizosphere soils were examined 14 days after H20-5 treatment using Illumina MiSeq sequencing of the bacterial 16S rRNA gene. Although the abundance of H20-5 rapidly decreased in the bulk and rhizosphere soils, a shift in the bacterial community was observed following H20-5 treatment. The variation in bacterial communities due to H20-5 treatment was higher in the rhizosphere than in the bulk soils. Additionally, the bacterial species richness and diversity were greater in the H20-5 treated rhizosphere than in the control. The composition and structure of the bacterial communities varied with soil salinity levels, and those in the H20-5 treated rhizosphere soil were clustered. The members of Actinobacteria genera, including Kineosporia, Virgisporangium, Actinoplanes, Gaiella, Blastococcus, and Solirubrobacter, were enriched in the H20-5 treated rhizosphere soils. The microbial co-occurrence network of the bacterial community in the H20-5 treated rhizosphere soils had more modules and keystone taxa compared to the control. These findings revealed that the strain H20-5 induced systemic tolerance in tomato plants and influenced the diversity, composition, structure, and network of bacterial communities. The bacterial community in the H20-5 treated rhizosphere soils also appeared to be relatively stable to soil salinity changes.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.213-220
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• 2022

This study was conducted to investigate the effect of environmental factors such as water temperature and rearing density on the survival and growth of Litopenaeus vannamei under low salinity conditions. Overall, in the higher water temperature, the higher survival rate comes out and in the lower rearing density, the higher the survival rate does. In a study on feed efficiency, weight gain (WG) increased significantly as water temperature increased, and weight gain according to rearing density significantly decreased as rearing density increased. The growth rate of L. vannamei was faster when the water temperature was higher (water temperature 31℃) under low salinity conditions. In addition, in the evaluation of the growth rate according to the rearing density, it was confirmed that the growth rate was accelerated at a low rearinging density. It is believed that the results of this study will be usefully applied to the determination of the optimal rearinging density and breeding water temperature of L. vannamei in low salinity condition.