• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.71-77
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• 2001

In order to find out the environmental factors influencing the catch of fyke nets in the coastal waters Yosu, the oceanographic factors, i.e., the waters temperature and the salinity were observed respectively from April to November in 1999, and each of them was compared with the catch of common mullet, Mugil cephalus by fyke net. The results obtained are summerized as follows : 1. The water temperature was ranged from 13.0 to $25^\circ$C and water temperature increased from April to August and decreased on September to November. 2. The range salinity in the fishing grounds was from 28.6 to 33.8$\textperthousand$, and salinity was high from April to June. From July, however, the salinity decreased to continue a low value still september. 3. The catches of common mullet caught by funnel net were the highest in may and the smallest in November. The ranges of optimum water temperature for the funnel nets fishing was 15.0 to $16.0^\circ$C, the ranges of optimum salinity for fishing varied between from 32.6 to 33.8$\textperthousand$.

• Ocean and Polar Research
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• v.29 no.1
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• pp.33-42
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• 2007

To obtain the overall distribution patterns and characteristics of the East Sea Intermediate Water (ESIW), the historical data obtained by the Japan Maizuru Marine Observatory (MMO) and the Korea Ocean Research and Development Institute (KORDI) were analyzed. To obtain water characteristics of the ESIW on isopycnal surfaces, temperature, salinity and dissolved oxygen were interpolated at every 0.01 interval of potential density. And then the interpolated values were averaged at the same potential density. This potential density average method preserved the salinity minimum layer more clearly compared to the depth average method. The potential density(${\sigma}_{\theta}$) range of the ESIW was $26.9{\sim}27.3$. The representative potential density of the ESIW was found to be 27.2, because the characteristics of the ESIW was clear at this density. From the horizontal distributions of physical properties on the isopycnal surface of $27.2{\sigma}_{\theta}$ it is suggested that the low salinity ESIW circulates anticlockwise over the whole basin with the high salinity intermediate water. The low salinity intermediate water extended from the northwestern part to the east along the sub-polar front and to the Ulleung Basin along the east coast of Korea.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.113-113
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• 2022

Salinity in surface waters is increasing around the world. Many factors, including increased water extraction, poor irrigation management, and sea-level rise, contribute to this change, and posing a threat to plant development and agricultural production. Seeds exposed to high salinity, have a lower probability of germinating and various physiological and biochemical effects. Salinity stress affects more than 20% of agricultural land and about 50% of irrigated land. In the current study, our objective is to identify the salt-tolerant peanut (Arachis hypogaea L.) Korean genotypes under salinity stress. Thus, two-week-old 19 diverse peanut Korean genotypes were exposed to 10 days of salinity (150 mM NaCl) stress. Based on the growth attributes investigation, Baekjung and Ahwon genotypes showed significantly higher shoot lengths compared to control plants. Whereas, the Sinpalwang genotype exhibited a significantly positive response for plant growth and reduced wilting symptoms compared to other genotypes. This study was able to find out peanut tolerant and sensitive genotypes for salt stress. These results may provide a good template for further salt-tolerant peanut cultivar improvement programs. Identified diverse salt-responsive genotypes can be utilized as source material in Korean breeding schemes for peanut crop improvement for salt and other abiotic stress tolerance.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.513-523
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• 2017

We evaluated the viability of phytoplankton along the salinity gradient in the flood and ebb tides of spring tide of February and the ebb tide of neap tide of March 2017 in the Seomjin River Estuary. Additional laboratory experiments were also conducted to determine the reason of the pH changes along the salinity gradient using the field natural sample in February. In field, saltwater was well mixed at downstream vertically and the salinity gradient was horizontally appeared toward upstream of freshwater zone. There were strong negative correlations between salinity and nutrient (nitrate + nitrite R=0.99, p<0.001, and silicate R=0.98, p<0.001), implying that those two nutrients of freshwater origin were gradually diluted with mixing the saltwater. On the other hands, relatively high phosphate concentration was kept in the stations of saltwater over 15 psu, indicating that it was caused by resuspended sediments of Gwangyang Bay and downstream by tidal water mixing.Among phytoplankton community structure in winter, Eucampia zodiacus have occupied to be c.a. 70 % in the most stations. Based on the field survey results for survivability of phytoplankton by phytoPAM instrument, there was positive correlations between salinity and chlorophyll a (R=0.82, p<0.001) and, salinity and active chlorophyll a (R=0.80, p<0.001), implying that the dominant marine diatom species may have significantly damaged in low salinity conditions of upstream. Also, maximum mortality rate of phytoplankton caused by low salinity shock was appered to be 75% in the upstream station. In particular, the pH in spring tides of February had tended to increase with high phytoplankton accmulated stations, suggesting that it was related with absorption of $CO_2$ by the photosynthesis of dominant diatom. In laboratory experiments, phytoplankton mass-mortality caused by low salinity shock was also occurred, which is confirmed with reducing the photosynthetic electron transport activity. Following the phytoplankton mass-mortality, bacteria abundance was significantly increased in 24 hours. As a result, the mass-proliferating bacteria can produce the $CO_2$ in the process of biodegradation of diatoms, which can lead to pH decrease. Therefore, marine phytoplankton species was greatly damaged in freshwater mixing area, depending on along the salinity gradient that was considered to be an important role in elevating and reducing of pH in Seomjin River Estuary.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.6
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• pp.492-499
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• 2009

Effect of drip irrigation on soil salinity control and growth of vegetable crops was studied in the three reclaimed lands of Korea in 2007. Drip irrigation was done one or two times per month for reduction of salt stress by using vinyl hose with tiny holes laid on ridge surface under black plastic film mulch during growing season of cabbage and chinese cabbage. It was observed that drip irrigation was generally effective to soil salinity control, but soil salinity variation of some place was not fully solved to lower down under level of free salt stress. It is also considered that high salinity of runoff water spilled out from cultivation ridge plays another key role for soil salinity management. Consequentially, this soil salinity variation might be one of factors brought low average yield and low commercial ratio of agricultural products. Relation between soil salinity and head growth of cabbage and chinese cabbage was well expressed as logarithmic function. Surface soil EC to reach at 50% of growth reduction to the heaviest head can be estimated was $6.1dS^{\circ}{\S}m^{-1}$ for cabbage and $5.7dS\;m^{-1}$ for chinese cabbage transplanted at optimum season.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.316-316
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• 2017

The objective of this study is to estimate quantitatively soil salinity and soil loss at upland soils in agriculture land region in Saemangeum reclaimed land on the south Korea coasts. Soil loss and soil salinity are the most critical problem at reclaimed tidal saline soil in Korea. The several thematic maps of research area such as land cover map, topographic and soil maps, together with tabular precipitation data used for soil erosion and soil salinity calculation. Meteorological data were measured directly as air temperature, wind speed, solar radiation, and precipitation. The experiment was conducted 2% sloped lysimeter ($5.0m{\times}20.0m$) with 14 treatments and it were separated by low salinity division (LSD) and high salinity division (HSD) install. The cation content in ground water increased during time course, but in the case of land surface water the content was variable, and $K^+$ was lower than that of $Na^+$ and $Mg^{2+}$. At the LSD under rainproof condition, the salinity was directly proportional to soil water content, but at the HSD the tendency was no reversed. In condition of rainproof, the amount of soil salinity was higher at the HSD than at the LSD. Positive correlation was obtained between the soil water content and available phosphorous content at the rainfall division, but there was no significance at the surface soil of the rainproof division. Sodium adsorption ratio and anion contents in soil were repressed in the order of vinyl-mulching > non-mulching > bare field. According to the result of analyzing soil loss, soil loss occurred in a vinyl-mulching, a non-mulching and a bare field in size order, and also approximately 11.2 ton/ha soil loss happened on the reclaimed land area. The average soil loss amount by the unit area takes place in a non-mulching and bare field a lot. Our results indicate that soluble salt control and soil erosion are critical at reclaimed tidal saline soil and the results can provide some useful information for deciding management plans to reduce soil loss and salt damage for stable crop production and diverse utilization or cultivation could be one of the management options to alleviate salt damage at reclaimed tidal saline soil in Korea.

• The Korean Journal of Malacology
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• v.24 no.3
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• pp.175-188
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• 2008

This study was performed to describe the influence of water temperature and salinity on the filtration rate of the hard clam, Meretrix petechialis. The filtration rates of hard clams showed significant differences depending on both water temperature and age group (two-way ANOVA, p < 0.001). The filtration rate of all the hard clams, aged from 1 to 4 years, was generally reduced in low temperature range ( $5-15^{\circ}C$). As the water temperature increased, the filtration rate increased exponentially. The filtration rate was relatively high in $20-30^{\circ}C$ water temperature range, but rapidly decreased again at around $35^{\circ}C$. Variations in the data for filtration rates of hard clams, relative to age and changing water temperature, were used to determine the temperature coefficient $Q_{10}$ in each water temperature range. In $5-15^{\circ}C$ temperature range, every age group showed the highest $Q_{10}$ figure. It was found that on the whole, the higher the water temperature was, the lower the number of $Q_{10}$ was. Regardless of age, the number of $Q_{10}$ was higher in the lower water temperature range. In $25-35^{\circ}C$ temperature range, the number of $Q_{10}$ was less than 1.00 in all age groups, implying that this is the range in which the filtration rate decreased. Variations in the filtration rate also showed very clear differences (two-way ANOVA, p < 0.001) according to changing salinity and age. All the age groups, from 1 to 4 year olds, showed low filtration rates at both low salinity (10-15 psu) and high salinity (40 psu). The highest filtration rate was recorded at 30 psu, and relatively high filtration rates were found around 30 psu. However, the Student-Newman-Keuls post hoc multiple comparison test found that the hard clams in the 1-year group showed high filtration rates in a relatively narrower salinity range compared to those in the 2, 3, and 4 year groups. In other words, hard clams in the 2, 3, and 4 year groups showed high filtration rates at higher levels of salinity.

• Asian Journal of Turfgrass Science
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• v.13 no.1
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• pp.21-28
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• 1999

The seeds of Zoysiagrass (Zoysia japonica Steud.) were soaked with GA3 50 ppm and primed with CaCl2 at -1.0 MPa for 4days at 23$^{\circ}C$ to identify presoaking and priming regimes that may improve germination in saline condition and with PEG 8000 at high temperature. Presoaked, primed, and untreated seeds were then germinated at 30 and $35^{\circ}C$. NaCl salinity stress consistently decreased the rate of germination of zoysiagrass seed. GA3 or CaCl2 alleviated the inhibitory effect of salinity on germination. However, total percent germination (G) and T50 of untreated control seeds significantly decreased and prolonged at $30^{\circ}C$ and $35^{\circ}C$ as NaCl salinity stress increased. Presoaked seeds with GA3 50 ppm for 4 days at $23^{\circ}C$ had significantly higher germination and lower T50 than untreated or primed with CaCl2 at -1.0 MPa for 4days at $23^{\circ}C$m and overcame the inhibitory effect of germination derived from PEG 8000. In addition, presoaked seed had higher, faster, and more uniform germination than untreated seeds after sowing in growing media in greenhouse.

• Korean Journal of Environmental Biology
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• v.31 no.2
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• pp.165-171
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• 2013

The distribution patterns of estuarine copepods were investigated in the Seomjin River estuary of southern Korea after heavy rains in August 2006. Tidal influence extended 16 km from the estuary mouth. Each estuary zone (Oligohaline salinity <5, mesohaline salinity 5~18, polyhaline salinity >18) changed within a range of about 5~6 km between low and high tides. A total of ten species were recorded, of which Pseudodiaptomus koreanus, Sinocalanus tenellus, and Tortanus dextrilobatus were predominant in the oligohaline zone; Acartia ohtsukai and Acartia forticrusa in the mesohaline zone; and A. erythraea, Calanus sinicus, Centropages dorsispinatus, Labidocera rotunda and Paracalanus parvus s. l. in the polyhaline zone. Their density was fastly reduced in the other zones. In particular, the oligohaline species migrated and aggregated into deeper water during ebb tides in order to retain their populations, while the same tendency was weaker for polyhaline species, suggesting that evolutionary traits primarily control population retention behaviors in estuarine environments.

• Journal of Environmental Science International
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• v.18 no.2
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• pp.141-151
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• 2009

Temperature, salinity, COD, DIN (Dissolved Inorganic Nitrogen), DIP (Dissolved Inorganic Phosphorus), and Chlorophyll ${\alpha}$ obtained from the southern coastal waters during the period of 2003 to 2005 were analyzed. Variability in temperature was not found between groups in southern coastal waters, but significantly different depending on sampling sites (p<0.05). The average temperature in 2003 estimated at $18.33^{\circ}C$ that was annually increased by 2005 and significantly different based on statistics (p<0.05). Unlikely to temperature, salinity was significantly different depending on sampling sites, as well as monthly variations (p<0.05). Likewise to temperature, the value of salinity was annually increased. COD estimated at the average of $>1.7\;mg\;l^{-1}$ for three years, indicating optimal water quality. The fluctuations of nutrients were extremely shown in different sampling sites and monthly variations. Chlorophyll a recorded above $2.0{\mu}g\;l^{-1}$ which was associated with high primary phytoplankton, whereas it showed much fluctuations in temporal and spatial, In particular, Tongyong, Jaranman, Jinjuman, and Samcheonpo located in the southeast were the highest fluctuations in water quality than any other regions. The correlation between salinity/COD and nutrients/chlorophyll a was strongly negative or positive, which was possibly associated with much the introduction of run-off water as well as rainfall in summer.