• Korean Journal of Community Nutrition
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• v.25 no.5
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• pp.386-395
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• 2020

Objectives: The aim of this study was to investigate sodium reduction practices in school foodservice in Daegu. Methods: The survey included 199 nutrition teachers and dietitians working at elementary, middle and high schools in Daegu. The survey topics included the following: the frequency of salinity measurement, workers in charge of the measurement, average salinity of the soup and stew served, frequency and difficulties of offering low-sodium meals, Importance-Performance Analysis (IPA) of sodium reduction methods in school foodservice and the need for political support in encouraging sodium reduction. Results: The mean salinity of the soup and stew was higher in high school foodservice than in elementary and middle school foodservice. Middle and high schools have difficulties in offering low-sodium meals due to concerns of decreasing satisfaction for the meals. The results of the IPA of programs to reduce sodium in school meals showed that most of the items in the cooking and serving stages were in the 2nd quadrant (Keep up the good work), and all purchasing and menu planning stages occupied the 3rd quadrant (Low priority). To reduce sodium in school meals, government support is required in developing low-sodium recipes for school foodservice, encouraging education on sodium reduction for school foodservice officials and developing low-sodium food for institutional foodservice. Conclusions: To encourage sodium reduction in school meals, the priority is to make low-sodium recipes available. Also, it is necessary to develop a program that calculates the sodium content in menus and processed foods through National Education Information System and to establish standards for sodium levels in school foodservice.

• Fisheries and Aquatic Sciences
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• v.23 no.7
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• pp.19.1-19.14
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• 2020

Three generalized additive models were applied to the distribution of anchovy eggs and oceanographic factors to determine the occurrence of anchovy spawning grounds in Korean waters and to identify the indicators of their occurrence using survey data from the spring and summer of 1985, 1995, and 2002. Binomial and Gaussian types of generalized additive models (GAM) and quantile generalized additive models (QGAM) revealed that egg density was influenced mostly by ocean temperature and salinity in spring, and the vertical structure of temperature, salinity, dissolved oxygen, and zooplankton biomass during summer in the upper quantiles of egg density. The GAM and QGAM model deviance explained 18.5-63.2% of the egg distribution in summer in the East and West Sea. For the principle component analysis-based GAMs, the variance explained by the final regression model was 27.3-67.0%, higher than the regular models and QGAMs for egg density in the East and West Sea. By analyzing the distribution of anchovy eggs off the Korean coast, our results revealed the optimal temperature and salinity conditions, in addition to high production and high vertical mixing, as the key indicators of the major spawning grounds of anchovies.

• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.367-373
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• 2005

We conducted a year-long survey in 2000 to examine seasonal fluctuations in the abundance of the demersal copepod Pseudodiaptomus sp., the dominant copepod in the Seomjin River estuary, where the spring tide strongly affects changes in salinity gradients. Pseudodiaptomus sp. was found throughout the year in the entire range of salinities measured, but most individuals appeared at oligohaline conditions below 5.0 psu, and less than $2\%$ were observed in polyhaline conditions above 18.0 psu. The peak abundance occurred during autumn in oligohaline waters, and the density was relatively low during the rainy season in summer. In spring and autumn, copepodites were most abundant in oligohaline waters, although they were also fairly abundant in mesohaline conditions $(5\~18\;psu)$. Females with egg sacs appeared in oligo- and mesohaline waters during spring and autumn but were seldom found in polyhaline conditions throughout the year. Our results indicate that, despite the strong physical influence of the tide, Pseudodiaptomus sp. can manipulate its position to remain at its preferred salinity. We also found that spawning mainly occurred in oligohaline waters twice a year.

• ALGAE
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• v.18 no.1
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• pp.49-58
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• 2003

The short-term dynamics of the summer phytoplankton community structure were investigated in coastal waters around Namhae Island, the Southern Sea of Korea. The study was based on a comprehensive survey constituting 39 collections from 13 stations on July 18-22, August 1-2, 14-16 and 27-30, respectively. The community structure was analysed using cluster analysis and important environmental correlates of the assemblage structure were identified with canonical correspondence analysis (CCA). Water temperature, salinity, NO₂, NO₃, NH₄, PO₄, chlorophyll a and transparency were measured as physico-chemical environmental factors which may be associated with the phytoplankton community structure. Variations of salinity and concentrations of NO₃ and chlorophyll a were not significant. In addition to warmer water temperature, concentrations of NO₂, NO₄and PO₄ decreased at the beginning of August. And transparency was deeper and water column became very unstable after the middle of August. A wide taxonomic diversity was encountered during the survey, including a total of 121 taxa which was composed of 72 diatoms, 48 dinoflagellates and 1 euglenoid species. Cluster analysis showed that the Phytoplankton community could be divided into 4 distinct groups, indicating rapid changes of the community in the short course of this survey. These phytoplankton groups also showed distinctive dispersion patterns in 2-dimensional canonical space, indicating distinct groupings for stations at each survey. Dominant taxa of diatoms (Chaetoceros curvisetus, Chaetoceros spp., Leptocylindrus danicus, Leptocylindrus mediteraneus, Skeletonema costanum, and Pseudo-nitzschia pungen) clustered in region of CCA space corresponding to stations surveyed at the middle of July. Dominant taxa of dinoflagellates were tightly associated with stations surveyed at the middle (Karenia breve) and end (Cochlodinium polykrikoides and Polykrikos schwartzii) of August. The CCA also showed that the phytoplankton community compositions were highly associated with water temperature, transparency, NO₂, NH₄ and PO₄, suggesting that gradients in physical and nutrient conditions affect short-term changes in phytoplankton composition.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.260-266
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• 2013

This study was conducted to investigate changes of vegetation and soil characteristics to tidal land of Saemangeum reclaimed land from 2010 to 2012. Soil salinity was 0.16-22.3 dS $m^{-1}$ in the first survey, while the three years later, it was decreased to 0.12-4.22 dS $m^{-1}$. Vegetations were classified as 6 families and 26 species but it was increased to 8 families and 31 species after three years. Numbers of average species in survey site were increased from 7.1 species to 10.6 species. Numbers of vegetation were increased at each survey sites except for survey site 7 : there was decreased halophyte according to decrease in the soil salinity. Biomass production was increased at low production site, and showed highest production in area of dominant vegetation as Phragmites communis. Simpson's dominance ratio(SDR) of main vegetation as Phragmites communis, Calamagrostis epigeios were increased but Suaeda maritima, Salicornia europaea, Puccinellia nipponica and Zoysia sinica were decreased.

• Ocean Science Journal
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• v.42 no.1
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• pp.41-48
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• 2007

We investigated the temperature and salinity effects on the major fish species in the wintering grounds based on trawl surveys and oceanographic observations in the southwestern waters of Korea during March-early April in 2002-2003. The influence area of warm Kuroshio water was limited to the southwestern area of Korea in 2003 with a range of $7.7-16.3^{\circ}C$, 32.54-34.70 of salinity, wider than that of 2002. The number of fish species and density of major fish species in 2003 were higher than in 2002. Geographical estimation showed high proportions of species number and catches in the areas around Jeju Islands, southwestern waters and the southeastern coast of Korea. Five species; silver pomfret (Pam pus echinogaster), hairtail (Trichiurus lepturus), anchovy (Engraulis japonicus), Small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were most abundant, composing above 60% of the total catch in 2002 and 2003. More than 50% of catch in the major fish species were mostly distributed in the range of $9.5-11.0^{\circ}C$ of temperature and 33.1-33.9 of salinity. Non-parametric estimation for the major species showed the 1st mode around $10^{\circ}C$ and the 2nd mode at $8-9^{\circ}C$ in 2002 and $11-14^{\circ}C$ in 2003. Among major fish species, hairtail was principally composed of juveniles, and larger individuals were caught in southeastern waters. These results are considered to be helpful for the area-based fishery management strategy for the wintering grounds of the Yellow Sea and coastal waters of Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.5
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• pp.57-65
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• 2007

The objective of this study was to evaluate chemical water quality by hourly monitoring(25hr) of Saemangeum esturary. For this study, we selected 2 sites like a Mangyong Bridge(St. 6) and Dongjin Bridge(St. 7). Inflow of salt water was not detected during low tide(maximum 553, 508cm) of all stations, while the salinity rises were detected in spring tide(750cm). When 602m of maximum tide was reached, salinity concentration was increased at St. 7, while there was no change in St. 6. Therefore, We know that salinity variation is greatly influenced by tide height at survey site. Also, significant variance of salinity(p<0.05) was found between St. 6 and St. 7 because dike construction made the flood tide move into the Dongjin river. Total suspened solids(TSS) concentration was increased because of the river runoff at St. 6, and also the turbulance and resuspension according to salt intrusion at St. 7. During the high tide, the water discharge from the sea seemed to dilute the nutrient but to elevate TSS concentration in St. 7. Silicate and nitrate concentrations in the studied site were decreased by the mixing of sea water, whereas the evident trend of phosphate concentration was not found. This result can be explained by the phosphorus condition. Phosphorus exists inactive when it is affected by hydrated iron and adsorbed onto suspended matters. Compared to the environmental conditions of the St. 6 and St. 7, physical factors such as temperature, dissolved oxygen and TSS have statistically no significant difference(p<0.001), but nutrient concentrations were higher at St. 6 than St. 7. It could be suggested from these results that it is important to control the discharge of fresh water by sewage treatment plants located in St. 6 for water quality management.

• 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.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1205-1215
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• 2002

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over III grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997~1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.

• Korean journal of food and cookery science
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• v.25 no.6
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• pp.671-676
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• 2009

In order to develop and propagate the low sodium kimchi for preventing high sodium related diseases, the salinity, pH and acidity of cabbage(Bachu) kimchi sampled from home located in 6 big cities(Pusan, Daegoo, Kyungjoo, Daegoo, Jeonjoo, Daejeon, and Seoul) and commercial 6 manufacturers(A~F) distributed in markets were monitored and analyzed in the current study. Salinity was significantly (p<0.05) higher in homemade($3.03%{\pm}0.60$: 1.79~4.40) kimchi than in commercial($2.38%{\pm}0.60$:1.04~2.87) kimchi. Also, salinity was significantly(p<0.05) higher in Pusan($3.45{\pm}0.60%$) kimchi than in Kyungjoo($3.11{\pm}0.39$), Daegoo($3.19{\pm}0.42$), Jeonjoo($2.98{\pm}0.32$), Daejeon($3.00{\pm}0.38$) and Seoul ($2.52{\pm}0.46%$) kimchi. However, there was no significant difference(p<0.05) of salinity in 6 kinds of commercial kimchi. Related to this result, pH of kimchi from homemade and commercial was $4.40{\pm}0.29$(3.72~6.03) and $5.45{\pm}0.76$ (4.23~6.35), acidity of kimchi from homemade and commercial were $0.99{\pm}0.30%$(0.28~2.17) and $0.45{\pm}023$(0.17~0.93), respectively. Thus, the current study provides evidence that we may need to manufacture the low sodium kimchi because all homemade kimchi, especially Pusan and Daegoo kimchi and commercial brand kimchi contained over 2% salinity.