• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.689-697
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• 2020

Hazardous and noxious substances (HNS) may cause maritime incidents during marine transportation, which are liable to lead to a large amount of spillage or discharge into the sea. The damage to the marine environment caused by the HNS spill or discharge is known to be much greater than the damage caused by oil spill. Particularly dangerous is HNS, which is deposited or buried in the seabed, as it can damage the organisms that live on, in, and near the bottom of the sea, the so-called "benthos," forming the benthic ecosystem. Therefore, it is vital that the HNS deposited on the seabed be recovered. In order to do so, procedures and equipment are required for accurate detection, stabilization treatment, and recovery of HNS in subsea sediment. Thus, when developing a mechanical recovery system, the performance requirements should be selected using performance indices, and the conceptual design of the mechanical recovery system should be based on performance requirements decided upon and selected in advance. Therefore, this study was conducted to arrive at a conceptual design for a mechanical recovery system for the recovery of HNS deposited on the seabed. In the design of the system, based on the fundamental scenario, the method of suction foundation with the function of self enclosing was adopted for recovering the HNS sediment in the subsea sediment. The mechanical recovery system comprises the suction foundation, pollution prevention, a pump system, control system, monitoring device, location information device, transfer device, and tanks. This conceptual design is expected to be reflected and used in the basic design of the components and shapes of the mechanical recovery system.

• ALGAE
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• v.31 no.1
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• pp.73-84
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• 2016

Marine organisms are frequently used to be harmful and have lower side effects than synthetic drugs. The cognitive improving efficacy of gamma aminobutyric acid-enriched fermented Saccharina japonica (FSJ) on the memory deficient rats, which were induced by trimethyltin chloride (TMT), was investigated by assessing the Morris water maze test and by performing choline acetyltransferase (ChAT), cAMP response element binding protein (CREB), and brain derived neurotrophic factor (BDNF) immunohistochemistry. The neurite outgrowth of Neuro2a cells was assessed in order to examine the underlying mechanisms of the memory enhancing effects of FSJ. Treatment with FSJ tended to shorten the latency to find the platform in the acquisition test of the Morris water maze at the second and fourth day compared to the control group. In the probe trial, the FSJ treated group increased time spent in the target quadrant, compared to that of the control group. Consistent with the behavioral data, these treatments recovered the loss of ChAT, CREB, and BDNF immunepositive neurons in the hippocampus produced by TMT. Treatment with FSJ markedly stimulated neurite outgrowth of the Neuro2a cells as compared to that of the controls. These findings demonstrate that FSJ may be useful for improving the cognitive function via regulation of neurotrophic marker enzyme activity.

• Ocean Science Journal
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• v.41 no.1
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• pp.11-29
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• 2006

We investigated species composition and spatial distribution of the euphausiid community in the Yellow Sea and identified the relationship with environmental factors (temperature, salinity, chlorophyll $\alpha$, nitrate, phosphate, and silicate) using bimonthly data from June, 1997 to April, 1998. The environment varied during the sampling period. In warm seasons, thermocline was well developed rendering lower temperature and higher salinity and nutrient concentrations in the bottom layer. During cold seasons the water column was well mixed and no such vertical stratification was noted. Horizontal distribution of temperature, however, differed slightly between near-coast and offshore areas because of the shallow depth of the Yellow Sea, and between southern and northern areas because of the intrusion of water masses such as Yellow Sea Warm Current and Changjiang River Diluted Water. Four euphausiid species were identified: Euphausia pacifica, E. sanzoi, Pseudeuphausia sp. and Stylocheron affine. E. sanzoi and S. affine were collected, just one juvenile each, from the southern area in June and December, respectively. Pseudeuphausia sp. were collected in the eastern area all the year round except June. E. pacifica occurred at the whole study area and were the predominant species, representing at least 97.6% of the euphausiid abundance. Further, the distribution pattern of the species was varied in regards to developmental stages (adult, furcilia, calyptopis, egg). From spring to fall, E. pacifica adults were abundant in the central area where the Yellow Sea Bottom Cold Water prevailed. Furcilia and calyptopis extended their distribution into nearly all the study area during the same period. From late fall to winter, adults were found at the near-coastal are a with similar pattern for furcilia and calyptopis. The distribution pattern of E. pacifica was consistent regarding temperature, salinity, and three nutrients during the sampling period, whereas chlorophyll $\alpha$ showed a different pattern according to the developmental stages. The nutrients should indirectly affect via chlorophyll $\alpha$ and phytoplankton concentration. With respect to these results, we presented a scenario about how the environmental factors along with the water current affect the distribution of E. pacifica in the Yellow Sea.

• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.25-33
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• 2010

Effects of different salinity levels on spawning performance, embryonic development and early viability of a euryhaline medaka species, Oryzias dancena, were examined. O. dancena were able to spawn eggs in a wide range of salinity from 0 to 70$^{\circ}/_{\circ\circ}$, however, the spawning frequency was lowered in complete freshwater (0$^{\circ}/_{\circ\circ}$) and in highly salted water (70$^{\circ}/_{\circ\circ}$). Fertilization success was negatively affected when the environmental salinity was higher than the salt concentration found in normal seawater. Embryonic viability and hatching success were also inversely related with the salinity levels. Typical abnormality was observed in developing embryos incubated at high salinities (30, 45 and 60$^{\circ}/_{\circ\circ}$). In addition, the time to hatch was significantly delayed with increasing salinities: peak hatching occurred at 12~14 days post fertilization (dpf) in freshwater and at least at 17 to 18 dpf in 60$^{\circ}/_{\circ\circ}$. Mean survival rates of the hatched larvae up to 7 days post hatching (dph) were at least 97% in salinity levels ranging from 0 to 30$^{\circ}/_{\circ\circ}$. However, larvae reared in 45 and 60$^{\circ}/_{\circ\circ}$ experienced significant mortality, especially in the early phase, resulting in only 75% and 64% survival rates up to 7 dph, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.6
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• pp.508-513
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• 2000

In an attempt to evaluate the fertilizer of sediments obtained from coastal farming areas, chemical composition, bacteriological quality and heavy metals in the sediments alkalized by quicklime and magnesium hydroxide were analyzed. The optimum conditions of alkalization were also measured. A perfect reaction was possible by the addition of quicklime of $30{\%}$ at the rate of $25{\%}$ of sediment and $100{\%}$ of livestock wastes. According to the classification standard for compost constituent by Higgins, all composts had the intermediate or high grade in $T-N, K_2O,\;CaO\;and\;MgO$, but below the low grade in $P_2O_5$, Stabilization by quicklime and magnesium hydroxide has been known to inhibit bacterial decomposition of organic matter and activity of pathogenic organisms. In this study, raising pH of stabilized sediments to 12 for 2 hours (PSRP rriteria of EPA) allowed $99.9{\%}$ of coliform group, fecal group and viable cell count to be reduced. As a result, sediments of coastal farming areas are likely to be used to produce the organic fertilizer by alkaline stabilization.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.157-164
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• 2009

In order to rehabilitate habitats for marine organisms in the slag dumping area, succession of benthic communities was monitored on artificial seaweed beds with transplantation of Ecklonia stolonifera from April 2004 to June 2005. Acinetospora critina was only primary dominated on steel frame in the first experiment (April 2004). A total of 15 species of seaweed were identified in the second experiment (June 2004). Enteromorpha intestinalis and Enteromorpha sp. were dominated, and Urospora penicilliformis, Ulothrix flacca, Cladophora sp., and Ulva pertusa were found on Ecklonia stolonifera fronds gradually with increasing time. This time was coincided with occurrence of benthic macrofaunas, molluscans and small fish species. The epiphytic benthic macrofaunas were dominated on amphipods, molluscans were Mytilus edulis, Thais clavigera, and fish species were Mugil cephalus, Pholis nebulosa. These results indicated that transplantation of Ecklonia stolonifera on artificial seaweed beds have been contributed on restoration habitats for benthic communities in the slag dumping area.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.3-15
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• 2003

Recently more than 450 incidents of oil spill a year have occurred in nearshore of Korea, which caused unmeasurelable losses in fisheries and severe damage in marine ecosystem. Two approaches remain paramount in any response to marine oil spill : the enhancement of natural dispersion of the oil by using dispersants, and mechanical recovery using booms and skimmers. A technique currently receiving fresh attention is the enhancement of the natural bioremediation of oil through the application of micro-organisms and/or nutrient. Oil, like many natural substances, will biodegrade over a period of time into simple compounds such as carbon dioxide, water and biomass. Bioremediation is the term used to describe a range of processes which can be used to accelerate natural biodegradation. More specifically biostimulation is the application of nutrients, and bioaugremetation or seeding is the addition of microbes specially selected to degrade oil. Bioremediation is an economically attractive method for the clean-up of oil-contaminated area. Bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mud flat environment.

• Journal of Marine Life Science
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• v.4 no.2
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• pp.45-52
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• 2019

Polycyclic aromatic hydrocarbons (PAHs) are persistent and commonly detected in marine ecosystem. They coexist with a various contaminants including heavy metals in real environment, but most studies have been still focused on single effects of these contaminants to aquatic organisms. In this study, the single and combined effects of benzy[a]pyrene (B[a]P) and HgCl₂ were investigated in the brackish water flea, Diaphanosoma celebensis. For combined effect study, three mixtures A (3:7), B (5:5), and C (7:3) of benzy[a]pyrene (B[a]P) and HgCl₂ were determined by 48 h - LC₅₀ values of single exposure. Combined effects of both chemicals were estimated by concentration addition (CA) model and independent action (IA) model. As results, 48 h - LC₅₀ values of benzy[a]pyrene (B[a]P) and HgCl₂ was 25.75 ㎍ l^-1 and 3.6 ㎍ l^-1, respectively. TU values of mixture A, B, and C were 1.06, 0.83, and 0.96, respectively, indicating additive effects of mixtures using CA model. This study will be helpful as basic data for understanding the combined effects of contaminants in marine environment.

• Korean Journal of Ecology and Environment
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• v.55 no.4
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• pp.376-389
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• 2022

Despite the consumption of disinfectants have been increased by COVID-19 pandemic, the fate of the chemicals in aquatic food webs are still unclear. In order to understand the trophic transfer of the chemicals, the concentration of disinfectants including six benzalkonium chloride (BACs) and five didecyldimethylammonium chlorides(DDACs) were measured at the Geum (2020), Han (2021), and Yeongsan River (2021), before and after rainfall. The highest concentration of ∑BACs (mainly C12 and C14) and ∑DDACs (mainly C10 and C14) were observed in the Han River, followed by Yeongsan River, Geum River Estuary, and Gapcheon. After rainfalls, both concentration and detection frequency were decreased in all sites. Although the BAC and DDAC seems to be accumulated in organisms, they were bio-diluted rather than magnified in the aquatic food web with the biomagnification factor(BMF) of less than 1, trophic magnification slope (TMS) from -0.236 to 0.001, and trophic magnification factor(TMF) from 0.85 to 1.01.

• Journal of Marine Life Science
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• v.3 no.2
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• pp.74-80
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• 2018

Mercury (Hg) poses a threat to marine ecosystem due to continuous inflow from various industries and bioaccumulation to higher trophic level via food web. Mercury can adversely affect growth, development, reproduction and metabolism to aquatic organisms. In the present study, acute toxicity and oxidative stress markers (total glutathione content, and activities of GST, GR and GPx) were investigated in brackish water flea Disphanosoma celebensis exposed to HgCl₂ for 24 h. As results, Hg showed negative effect in survival of D. celebensis. 24 h-LC₅₀ value was determined as 0.589 mg/l (95% C.I. 0.521~0.655 mg/l). After exposure to Hg (0.08 and 0.4 mg/l) for 24 h, total glutathione content was significantly decreased, whereas GST, GPx and GR activities were enhanced. These findings indicate that Hg induced oxidative stress in D. celebensis, and oxidative stress markers may be involved in cellular defense against Hg - mediated toxicity. This study provides a better understanding of molecular mode of action of Hg toxicity in this specie and potent of molecular markers for heavy metal monitoring in marine ecosystem.