• Journal of Marine Life Science
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• v.7 no.2
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• pp.205-212
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• 2022

Transport is essential in the farming process of farmed fish and is one of the physical stress factors such as sorting. The effect of water temperature and anesthesia during low salinity transport was confirmed. In the experimental group, the water temperature was set to 20℃ (natural water temperature, NWT), 15℃ (cooling water temperature, CWT) respectively, in water with a salinity concentration of 35‰, 15‰ and an anesthetic (anesthesia, Anes., Sigma USA) was diluted and mixed to 50 ppm. A styrofoam box (66×42×20 cm) was used as a transport container, and 8 flounder were accommodated and transported in a plastic bag injected with 3 ℓ of seawater and liquid oxygen. As a result of the study, the concentration of cortisol before transport increased significantly from 2.4±0.1 ng ml^-1 in the experimental groups except for the CWT+35‰ group (16.7±12.8 ng ml-1). The K⁺ concentration slightly increased from 3.1±0.0 mEq l^-1 before transport to 4.5±1.1 mEq l^-1 in the NWT+15‰ group, showing no difference, and significantly increased in all other experimental groups. There was no effect on changes in blood characteristics, and water temperature and anesthetic had a negative effect on osmotic control due to stress. AST and ALT were not affected.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.285-292
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• 2021

Osmotic power is to produce electric power by using the chemical potential of two flows with the difference of salinity. Water permeates through a semipermeable membrane from a low concentration feed solution to a high concentration draw solution due to osmotic pressure. In a pressure retarded osmosis (PRO) process, river water and wastewater are commonly used as low salinity feed solution, whereas seawater and brine from the SWRO plant are employed as draw solution. During the PRO process using wastewater effluent as feed solution, PRO membrane fouling is usually caused by the convective or diffusive transport of PRO which is the most critical step of PRO membrane in order to prevent membrane fouling. The main objective of this study is to assess the PRO membrane fouling reduction by pretreatment to remove organic matter using coagulation-UF membrane process. The experimental results obtained from the pretreatment test showed that the optimum ferric chloride and PAC dosage for removal of organic matter applied for the coagulation and adsorption process was 50 mg/L as FeCl₃ (optimum pH 5.5). Coagulation-UF pretreatment process was higher removal efficiency of organic matter, as also resulting in the substantial improvement of water flux of PRO membrane.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.443-450
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• 2015

The east coast of the Korean Peninsula is susceptible to fires because of the low rainfall in winter and spring, and large forest fires have occurred in this area. Lack of fresh water to combat fires has hampered efforts to prevent widespread forest fires in this region. Seawater has not been used as a suppressant because of possible detrimental effects of salt. We investigated the mobility of saline water in the forest soil and their effect on the microbial activity. Using a fire-fighting helicopter, seawater was sprayed over three plots (50 × 100 m) located on the eastern slope of the Baekdu mountain range in South Korea in April, 2011. We sampled the soil in April 4, May 20, and August 5 to determine the amount of salt that remained in the soil. The electrical conductivity value of the soil decreased to <400 μS/cm over a 1-month period. Approximately, four months after the application of seawater, the electrical conductivity value and Na⁺ content in all treatment plots did not significantly differ to those of the control plot, and total microbial activity also recovered to that of the control. Our results indicate that the amount of rainfall, soil physical-chemical properties, and topological factors may be a critical factor determining the mobility of saline water in forest soil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.451-455
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• 2012

Physicochemical water conditions and phytoplankton were investigated at Ggot-jee beach in Anmyondo, summer season of 2011. COD were sometimes recorded higher than 5.0mg/l and SS were always over 40mg/l. DO, pH and salinity were stable generally but low salinity was affected by heavy rainfall. In spite of relatively high concentrations of chlorophyll and phytoplankton standing stocks, discolored water phenomena(green or red tide) had not been occurred. A few dinoflagellate species were dominated in June and July, but general diatoms were dominant species of phytoplankton community in August. Escherichia coli concentrations were higher in August(>400CFU/100ml) than in July but it's not the level of hygienic problem.

• Journal of the Korean Society for Marine Environment & Energy
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• v.19 no.4
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• pp.274-285
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• 2016

In order to elucidate the spatiotemporal variations of marine environmental parameters, we collected seawater samples in the middle east coast of Korea in 2013-2014. A high temperature and low salinity were distinctively observed in the summer and a low temperature and high salinity pattern in the winter. The temperature of the bottom water was in the range of $2^{\circ}C$ to $7^{\circ}C$, with the temperature being relatively high in the winter, while the salinity was measured to be around 34, with no large differences across the seasons. The dissolved oxygen concentrations were in the range of $7mg\;L^{-1}$ to $12mg\;L^{-1}$, and it was relatively high in May compared to other seasons. The seawater temperature and dissolved oxygen concentration at the surface layer showed a significant negative correlation in the autumn and winter seasons, based on which it is seemed that water temperature is the main factor controlling the amount of dissolved oxygen in the autumn and winter seasons. The dissolved inorganic nitrogen (DIN) and silicate (DSi) increased 11- and 7-fold, respectively, in the winter compared to the summer. The DIN to DIP (dissolved inorganic phosphorus) ratio for the surface seawater was approximately 16, but it was relatively low in the spring season. On the other hand, the DIN to DIP ratio was relatively high in the summer. Based on this, it is seemed that nitrogen and phosphorus were the growth-limiting nutrients for phytoplankton in the spring and summer, respectively. Water quality was I (excellent) ~III (medium) level at the most stations except for some stations (level IV) during the autumn season, having low dissolved oxygen saturations.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.8-15
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• 2010

The effect of soil salinity and soil-wetting by rise of water table on the growth of fruit trees was studied to obtain information for orchard establishment in the Saemangeum reclaimed tidal land. Survival ratio of trees was 85%for grape, 31%for fig, 15%for apple and pear, and near zero for peach and blueberry. Wet injury induced by water-logged or flooded condition, rather than salt injury(soil EC was lower than 3.0dS $m^{-1}$ during growing period) is thought to be more responsible for low survival ratio of fruit trees transplanted in Saemangeum area. During the summer raining season in the reclaimed areas, the soil salinity tends to be decreased by natural rainfall effect, and the rainfall acceptable capacity(RAC) of soils dramatically is reduced(10-24 mm) as rainfall is continued to occur. In spite of high hydraulic conductivity(121 cm $day^{-1}$) of soils across the area, low RAC of soils might be due to high soil saturation and elevated water table during summer raining season. Therefore, the installation of effective drainage system should be the primary factor determining successful establishment of orchard in the Saemangeum reclaimed tidal land.

• Ocean and Polar Research
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• v.30 no.3
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• pp.289-301
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• 2008

Community structure of heterotrophic protists and their grazing impact on phytoplankton were studied in Northwest Pacific Ocean during October, 2007. The study area was divided into four regions based on physical properties (temperature and salinity) and chlorophyll-a distribution. They were Region I of North Equatorial Currents, Region II of Kuroshio waters, Region III of shelf mixed water, and Region IV of Tsushima warm current from East China Sea. The distribution of chlorophyll-a concentrations and community structure of heterotrophic protists were significantly affected by physical properties of the water column. The lowest concentration of chlorophyll-a was identified in Region I and II, where pico-sized chlorophyll-a was most dominant (>80% of total chlorophyll-a). Biomass of heterotrophic protists was also low in Region I and II. However, Region III was characterized by low salinity and temperature and high chlorophyll-a concentration, with relatively lower pico-sized chlorophyll-a dominance. The Highest biomass of heterotrophic protists appeared in Region III, along with the relatively less important nanoprotists. In Region I, II and IV, heterotrophic dinoflagellates were dominant among the protists, while ciliates were dominant in Region III. Community structure varied with physical(salinity and temperature) and biological (chlorophyll-a) properties. Biomass of heterotrophic protists correlated well with chlorophyll-a concentration in the study area ($r^2=0.66$, p<0.0001). The potential effect of grazing activity on phytoplankton is relatively high in Region I and II. Our result suggest that biomass and size structure of heterotrophic protists might be significantly influenced by phytoplankton size and concentration.

• 한국해양학회지
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• v.26 no.3
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• pp.278-290
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• 1991

A synoptic survey of chemical properties was carried out at 21 stations in the Ulleung Basin in May 1988 on board T/V HANBADA. Vertical structures of typical profiles are: surface mixedlayer waters in the upper 30∼40 m with depleted nutrients concentrations, thermocline waters with rapid variations in all physical and chemical properties. and deep Waters below 200 m which are nearly homogeneous. Along the northern section at 37$^{\circ}$12'N. The salinity minimum layer was observed at about 190m. which characterize the East Sea Intermediate Water (ESIW). The dissolved oxygen concentration in this layer was about 230∼ 275uM, lower than 290uM (6.5ml/l) which is the previously known characteristics of the ESIW. However, apparent oxygen utilization (AOU), nitrate, phosphate and silicate show systematically low concentration in the salinity-minimum layer. The low values of AOU and all the nutrients associated with the salinity-minimum, may be useful to identify the ESIW and serve as a new tracer in the East Sea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.119-126
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• 2021

In this study, the variability in paralytic shellfish poisoning (PSP) by the toxic dinoflagellate Alexandrium catenella (Group I) was analyzed under a variety of water temperatures and salinities. This dinoflagellate experienced optimum growth at temperatures and salinities of 20~30℃ and 20~30 psu, respectively. These findings indicate that A. catenella is an eurythermal and euryhaline organism. High toxin contents and toxicities were observed at low temperatures (10 and 15℃), where they were associated with low growth rates; salinity did not have any significant impact on toxicity parameters. Therefore, it is likely that A. catenaella contributes to the rapid intoxication of commercial bivalve when temperatures are ≤15℃. To better estimate PSP caused by A. catenalla, we suggest that the influence of various environmental factors controlling PSP should persist with other A. catenella stains and commercial bivalves.

• Journal of Food Hygiene and Safety
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• v.8 no.2
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• pp.13-21
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• 1993

Vibrio septicemia,, resulting in high mortality, has been caused by Vibrio vulnificus. Ingestion of marine products or contact with sea water contaminated with Vibrio vulnificus can cause septicemia. Vibrio vulnificus has been detected world wide and west sea area of Korea, Kum river estuary in particular, showed high detection rate. Higher detection rate of Vibrio vulnificus were reported in the bottom deposit with low depth of water, low salinity, and high COD. Man with the liver disease can easily come down with Vibrio septicemia and the main source is the sliced raw fish dish. The preventive measure for this disease is to wash raw fish material thoroughly with tap water and handle in sanitary conditions. Washing with sea water is strictly prohibited . It may be necessary to forbid the small-scale businessmen from selling the sliced ray fish dish in the vicinity of seashore. Man with the liver disease of diabetes should not swim or consume the raw fish dish in the contaminated area during summer.