• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.170-174
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• 1998

The water quality of offshore waters around the Korean coast was evaluated by bioassay using gametes, embryoss and early development systems of a sea urchin species Hemicentrotus pulcherrimus. The results show that despite the inflows of several river systems, the west coast maintain the grade II water. This is thought to be due to the decrease in pollutant input resulting from the purification of inflow rivers (e.g., the control of waste water discharge and the construction of sewage treatment facilities), and the dilution of pollutants by a strong tidal mixing with a large difference between the ebb and flood tides. However, Asan, Hampyong and Chonsu bays, where circulations of water are relatively poor, and the Kunsan and Mokpo harbors which are influenced by pollutants from neighboring cities have shown the grade III water. The south coast has maintain the grade II or III because developments of sea urchins were moderately or strongly inhibited. Also, Kangjin, Duekryang, Kwangyang, Masan, and Jinhae bays where water circulations are relatively poor, show the grade III water, with strong inhibitions of the early development of sea urchins. The east coast has maintained the grade I and II due to monotonous coastlines and smooth circulation of sea water. However, Chongcho Lake shows the worst water quality due to the breakwater which is constructed to maintain port functions.

• Journal of the Korean Geotechnical Society
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• v.28 no.10
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• pp.79-88
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• 2012

Small amount of salt and various microorganisms are contained in natural soils or clays near the shore. In this study, most common clay minerals such as kaolinite and bentonite are used to evaluate the effect of salt and microorganism on liquid and plastic limits. The effect of time after mixing clays with water was also investigated for the consistency limits of clays. The test was conducted immediately, 1 day, or 7 days after mixing soils. For liquid limit tests two different test methods were used, the percussion cup method by Casagrande and the fall cone method. When sea water or microbial solution was used for mixing soils rather than distilled water, the liquid limit of kaolinite decreased by 6-15% and that of bentonite further decreased up to 37-53%. The liquid limit obtained from the fall cone method was approximately 10% for bentonite and 20% for kaolinite, which are higher than those from the percussion cup method. The effect of time on liquid and plastic limits was significant for those tested immediately or 1 day later but the values obtained after 1 day or 7 days did not vary a lot, regardless of soils, mixing waters or test methods.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.787-796
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• 1996

The biodegradation experiment, the TOD analysis and the element analysis for dispersant, Bunker-A oil and Bunker-B oil were conducted to study the biodegradation characteristics of a mixture of Bunker-A oil with dispersant and a mixture of Bunker-B oil with dispersant in the seawater. The results of biodegradation experiment showed 1mg of dispersant to be equivalent to 0.26 mg of $BOD_5$ and to 0.60 mg of $BOD_{20}$ in the natural seawater. The results of TOD analysis showed each 1 mg of dispersant, Bunker-A oil and Bunker-B oil to be equivalent to 2.37 mg, 2.94 mg and 2.74 mg of TOD, respectively. The results of element analysis showed carbon, hydrogen, nitrogen and phosphorus contents of dispersant to be $82.1\%,\;13.8\%,\;1.8\%\;and\;2.2\%$, respectively. Carbon and hydrogen contents of Bunker-A oil were found to be $73.3\%\;and\;13.5\%$, respectively, and carbon, hydrogen and nitrogen contents of Bunker-B oil to be $80.4\%,\;12.3\%\;and\;0.7\%$, respectively. Accordingly, the detection of nitrogen and phosphorus in dispersant shows that dispersants should be used with caution in coastal waters, with relation to eutrophication. The biodegradability of dispersant expressed as the ratio of $BOD_5/TOD$ was found to be $11.0\%$. As the mix ratios of dispersant to Bunker-A oil (3 mg/l) and a mixture of Bunker-B oil (3mg/l) were changed from 1 : 10 to 5 : 10, the biodegradabilities of a mixture of Bunker-A oil with dispersant and Bunker-B oil with dispersant increased from $2.1\%\;to\;7.2\%$ and from $1.0\%\;to\;4.4\%$, respectively. Accordingly, the dispersant belongs to the organic matter group of middle-biodegradability while mixtures in the mix ratio range of $1:10\~5:10$ belong to the organic matter group of low-biodegradability. The deoxygenation rate constant $(K_1)$ and ultimate biochemical oxygen demand $(L_0)$ obtained from the biodegradation experiment and Thomas slope method were found to be 0.125/day and 2.487 mg/l for dispersant (4 mg/l), respectively. $K_1\;and\;L_0$, were found to be $0.079\~0.131/day$ and $0.318\~2.052\;mg/l$ for a mixture of Bunker-A oil with dispersant and to be $0.106\~0.371/day$ and $0.262\~1.106\;mg/l$ for a mixture of Bunker-B oil with dispersant, respectively, having $1:10\~5:10$ mix ratios of dispersant to Bunker-A oil and Bunker-B oil. The ultimate biochemical oxygen demands of the mixtures increased as the mix ratio of dispersant to Bunker-A, B oils changed from 1 : 10 to 5 : 10. This suggests that the more dispersants are applied to the sea for the cleanup of Bunker-A oil or Bunker-B oil, the more decreases the dissolved oxygen level in the seawater.

• Ocean Science Journal
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• v.40 no.3
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• pp.167-176
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• 2005

A time-series sediment trap was deployed at 1,034 m water depth in the eastern Bransfield Strait for a complete year from December 25, 1998 to December 24, 1999. About 99% of total mass flux was trapped during an austral summer, showing distinct seasonal variation. Biogenic particles (biogenic opal, particulate organic carbon, and calcium carbonate) account for about two thirds of annual total mass flux $(49.2\;g\;m^{-2})$, among which biogenic opal flux is the most dominant (42% of the total flux). A positive relationship (except January) between biogenic opal and total organic carbon fluxes suggests that these two variables were coupled, due to the surface-water production (mainly diatoms). The relatively low $\delta^{13}C$ values of settling particles result from effects on C-fixation processes at low temperature and the high $CO_2$ availability to phytoplankton. The correspondingly low $\delta^{l5}N$ values are due to intense and steady input of nitrates into surface waters, reflecting an unlikely nitrate isotope fractionation by degree of surface-water production. The $\delta^{l5}N$ and $\delta^{l3}C$ values of sinking particles increased from the beginning to the end of a presumed phytoplankton bloom, except for anomalous $\delta^{l5}N$ values. Krill and the zooplankton fecal pellets, the most important carriers of sinking particles, may have contributed gradually to the increasing $\delta^{l3}C$ values towards the unproductive period through the biomodification of the $\delta^{l3}C$ values in the food web, respiring preferentially and selectively $^{12}C$ atoms. Correspondingly, the increasing $\delta^{l5}N$ values in the intermediate-water trap are likely associated with a switch in source from diatom aggregates to some remains of zooplankton, because organic matter dominated by diatom may be more liable and prone to remineralization, leading to greater isotopic alteration. In particular, the tendency for abnormally high $\delta^{l5}N$ values in February seems to be enigmatic. A specific species dominancy during the production may be suggested as a possible and speculative reason.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.4
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• pp.294-302
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• 2019

As a series of fundamental researches on the development of an automatic identification monitoring system for fishing gear. Firstly, the study on the installation method of automated identification buoy for the coastal improvement net fishing net with many loss problems on the west coast was carried out. Secondly, the study was conducted find out how to install an automatic identification buoy for coastal gill net which has the highest loss rate among the fisheries. GPS for fishing was used six times in the coastal waters around Seogwipo city in Jeju Island to determine the developmental status and underwater behavior to conduct a field survey. Next, a questionnaire was administered in parallel on the type of loss and the quantity and location of fishing gear to be developed and the water transmitter. In the field experiment, the data collection was possible from a minimum of 13 hours, ten minutes to a maximum of 20 hours and ten minutes using GPS, identifying the development status and underwater behavior of the coastal gillnet fishing gear. The result of the survey showed that the loss of coastal net fishing gear was in the following order: net (27.3%), full fishing gear (24.2%), buoys, and anchors (18.2%). The causes were active algae (50.0%), fish catches (33.3%) and natural disasters (12.5%). To solve this problem, the installation method is to attach one and two electronic buoys to top of each end of the fishing gear, and one underwater transmitter at both ends of the float line connected to the anchor. By identifying and managing abnormal conditions such as damage or loss of fishing gear due to external factors such as potent algae and cutting of fishing gear, loss of fishing gear can be reduced. If the lost fishing gear is found, it will be efficiently collected.

• Microbiology and Biotechnology Letters
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• v.31 no.2
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• pp.95-102
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• 2003

Microalgae are a diverse group of photosynthetic organisms and abundant in every ecosystem in the biosphere. They are common in aqueous environments including marine, brackish and fresh waters and in some habitats that lack eukaryotic life such as some hot springs and highly alkaline lakes. Microalgal biotechnology that is focused on the microalgae-based production of a variety of useful materials such as pharmaceutical comfounds, health foods, natural pigments, and biofuels is considered as an important discipline with the development of biotechnology. In addition, the mass cultivation of microalgae can also contribute to improving the environmental quality by reducing the concentration of $CO_2$ which is one of major gases lead to global warming. Consequently, it seems that the microalgae can be used as an efficient, renewable, environmentally friendly source of high-value biomaterials such as chemicals, pigments, energy, etc. and the microalgal biotechnology will most likely represent a larger portion of modern biotechnology.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.48-52
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• 1982

Methods for the measurement of aquatic bacteria can be divided into two groups. The first group of these methods is based on the 'replicon' concept that live bacterial cells, when diluted and transferred to a suitable medium, produce colonies. These methods distinguish living from dead bacteria, but they massively underestimate bacterial numbers. The second group of enumeration methods uses visual counting technique using specific apparatus such as a microscope. These methods are generally direct and simple, but it is very hard to distinguish between live and dead bacteria and between small particle and bacteria. Recently developed technique in staining methods has provided a reliable method of visual determination of aquatic bacteria. This uses epifluorescence microscopy to measure the total bacterial population. In order to present the fluorescence microscopy as a new methodology for the determination of bacterial numbers in water supplies, data were obtained from chlorine and monochloramine doses added to samples. Total counts by fluorescence microscopy were compared with standard plate count method. The total number of bacteria in water supplies can be determined with fluorescence microscopy. This technique allows better resolution of small bacteria and differentiation of particle from bacteria. Chloramine was found to persist longer in natural waters and prevent bacterial regrowth.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.129-135
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• 2011

The possibility of nutrient removal during Scenedesmus sp. growth in Lake Paldang, Geongan cheon stream, and the outflow from a wastewater treatment system was examined. Scenedesmus sp. grew well in Lake Paldang water when total nitrogen (TN) and total phosphorus (TP) values were 1.9 and 0.02 mg $L^{-1}$, respectively, and 50% of the nutrients were removed. In Geongan cheon stream, the TN and TP was 3.0 mg $L^{-1}$ and 0.09 mg $L^{-1}$, respectively, chlorophyll-${\alpha}$ reached a maximum of 239~259 $m^{-3}$, and 50% of the nutrients were removed. In the wastewater treatment outflow, where Scenedesmus sp. already existed, the organism grew well without inoculation. Scenedesmus sp. can grow with proper inoculation and physical turbulence in natural waters, such as lake and stream water, and nutrients can be eliminated as phytoplankton growth occurs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.95-103
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• 2008

Heavy metals in the surface seawaters and sediments were measured in Gaduk channel of jinhae Bay. The high concentrations of heavy metals in the seawaters were found at the stations near the islands. In the seawaters, the mean concentrations of dissolved heavy metals except for Pb were not higher than previous data in this bay. Higher heavy metal contents in the surface sediments were observed at the stations adjacent to the Geojedo or Gadukdo of the Gaduk channel. The contents of Co,Ni,Zn,Cu,As and Cd in the surface sediments showed relatively high correlation coefficients with IL and COD. The order of enrichment factors(EFs) of heavy metals in the sediments on the basis of average shale values was As>Cd>Pb>Zn>Co>Cu>Hg>Ni, and the EFs of As,Cd,Pb and Zn at whole stations were higher than 1. EFs of Ni and Zn on the basis of natural background concentration in Korean coastal sediments were lower than EFs by average shale.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.535-541
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• 2005

Peat humin(p-Humin) extracted from Canadian Sphagnum peat moss was packed in a column and removal of heavy metal ions such as Cd, Cu and Pb from aqueous solution under flow conditions was studied. The metal ions were removed not only from single-element solutions but also from a multi-metal solution. Column kinetics for metal removal were described by the Thomas model. For single-component metal solutions, the maximum adsorption capacities of the p-Humin for Pb, Cu and Cd were 138.8, 44.66 and 41.61 mg/g, respectively. The results of multi-component competitive adsorption showed that adsorption affinity was in the order of Pb $\gg$ Cu > Cd. The adsorbed metal ions were easily deserted from the p-Humin with 0.05 N $HNO_3$ solution. It is apparent that 95% of the heavy metal ions were recovered from the saturated column. This investigation provides possibility to clean up heavy-metal contaminated waste waters by using the natural biomass, p-Humin as an environmentally friendly and cost-effective new biosorbents.