• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.3
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• pp.154-162
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• 2011

Seawater quality was investigated each month at 30 stations near Tongyeong, South Korea, to provide data for the effective use of coastal fisheries and the reduction of economic damage to marine products. Water temperature was lowest in January and highest at the end of August. Neither extremely low water temperature below $4^{\circ}C$ nor fish damage caused by low water temperature was observed. Salinity ranged from 24.04 to 34.39 psu in the surface layer and from 29.92 to 34.39 psu in the bottom layer. The minimum salinity, attributable to rainfall events, was observed in July; salinity increased to high of about 34 psu in November. Low dissolved oxygen (DO), below 4 mg/L, was observed at Wenmun and Buksin Bays during May to October. Concentrations of $NO_2$-N, $NO_3$-N, and $PO_4$-P were low from March to September and high from October to February. Transparency was 6 m on average and was high in Wenmun Bay. Chemical oxygen demand (COD) and chlorophyll a (Chl. a) were high during summer, when the water temperature was high. With cluster analysis based on environment factors related to water quality, the study area could be divided into three main sea areas: Buksin Bay, coastal seawater, and offshore seawater. Buksin Bay was characterized by low salinity, high DO and Chl. a, and high transparency in the surface layer and by low DO and high $NH_4$-N in the bottom layer. Offshore seawater had high salinity and $NO_3$-N and low Chl. a concentration. In summer season that oyster need lots of phytoplankton, $NO_3$-N and Chl. a concentrations at this study area were low compare to Gwangy-ang and Gamak Bays. In winter, a sea squirt swallow much more than other season, the Chl. a concentrations were also low than Gwangyang and Gamak Bays.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.1
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• pp.29-35
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• 2015

Dissolved nutrients in seawater are recognized as an essential biogeochemical factor for detecting global environmental changes. The importance of nutrient reference material for seawater has been increased greatly for the comparison of nutrient data, measured in different time and space in global ocean by various researchers with different levels in nutrient analysis skill. In this study, we described the homogeneity and stability of nutrient reference material for seawater using natural seawater, collected at a station of Shihwa Lake, at a coastal station near Uljin (surface water), and at a station over the Ulleung Basin (surface water and 1500 m depth water) and sterilized. Based on the homogeneity data, the nutrient reference materials has similar homogeneity compared to other nutrient reference materials. During 3-13 month period, there was no unidirectional trend of increase or decrease in nutrient concentration of newly developed nutrient reference material for seawater. However, a sustained measurement is required to check stability for longer period.

• Geophysics and Geophysical Exploration
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• v.5 no.1
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• pp.56-63
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• 2002

Tracing the history of study, problems of seawater intrusion are commonly investigated with electrical techniques because seawater saturated zone is indicative of the low resistivity anomaly. There we, however, silt and mud layers in the western and southern coastal areas of Korea, so we may make a mistake in case we determine seawater intrusion only with resistivity survey. Hence, reference IP survey was carried out in Kimje, Jeollabuk-Do and Youngkwang, Jeollanam-Do in order to decide whether or not the area is under the influence of seawater intrusion. With the use of a electric field cable to minimize EM coupling, we obtained more accurate results by appling reference If technique measuring simultaneously wavelet of current as well as potential. With the aid of reference IP technique, it is possible that we can exactly evaluate seawater intrusion by discriminating seawater saturated area (no IP effect) from very highly conductive layer composed of clay mineral (high IP effect).

• Proceedings of KOSOMES biannual meeting
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• 2008.05a
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• pp.177-180
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• 2008

Based on Latti(1974) and Jacobs&Way(1968)'s theory, we estimate the coastal area of Jeju and Busan cities. According to the estimateio, The seawater pumping line causes the problem of coastal landscape. Water management treatment of coastal region has been an important problem in Jeju city and Busan city since the distributions of pipeline if the pumping system made a bad view in coastal region. To solve the problem, we observed the pipelines that are on the surface around the coastal region we proposed two methods, that is, one is a short time treatment, the other is a long time one. The short is based on the colour treatment, which is pipeline colour changing into surround natural one. The long time is the construction plan design method. Although the later method was very useful in Jeju island. However, it takes a lot of time and money. Therefore, in the situation, the short time is the better than the long time one.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.156-162
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• 2005

Particularly in research related to seawater intrusion the change of fluid electrical conductivity is one of major concerns, and effective monitoring can help to optimize a water pumping performance in coastal areas. Special considerations should be given to the mounting of sensors at proper depth during the monitoring design since the vertical distribution of fluid electrical conductivity is sensitive to the characteristics of seawater intrusion zone. This tells us the multi-channel electrical conductivity monitoring is of paramount consequence. It, however, is a rare event when this approach becomes routinely available in that commonly used commercial stand-alone type sensors are very expensive and inadequate for a long term monitoring of electrical conductivity or water level due to their restricted storage and difficulty of real-time control. For this reason, we have developed a real-time monitoring system that could meet these requirements. This system is user friendly, cost-effective, and easy to control measurement parameters - sampling interval, acquisition range, and others. And this devised system has been utilized for the electrical conductivity monitoring in boreholes, Yeonggwang-gun, Korea. Monitoring has been consecutively executed for 24 hours, and the responses of electrical conductivity at some channels have been regularly increased or decreased while pumping up water. It, with well logging data implemented before/after pumping water, verifies that electrical conductivity changes in the specified depths originate from fluid movements through sand layer or permeable fractured rock. Eventually, the multi-channel electrical conductivity monitoring system makes an effective key to secure groundwater resources in coastal areas.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.309-323
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• 2020

Estimation of chlorophyll a concentration (CHL) on coastal areas using remote sensing has been mostly performed through multi-spectral satellite image analysis. Recently, various studies using hyperspectral imagery have been attempted. In particular, airborne hyperspectral imagery is composed of hundreds of bands with a narrow band width and high spatial resolution, and thus may be more effective in coastal areas than estimation of CHL through conventional satellite image. In this study, comparative analysis of hyperspectral and satellite-based CHL images was performed to estimate CHL in coastal areas. As a result of analyzing CHL and seawater spectrum data obtained by field survey conducted on the south coast of Korea, the seawater spectrum with high CHL peaked near the wavelength bands of 570 and 680 nm. Using this spectral feature, a new band ratio of 570 / 490 nm for estimating CHL was proposed. Through regression analysis between band ratio and the measured CHL were generated new CHL empirical formula. Validation of new empirical formula using the measured CHL showed valid results, with R² of 0.70, RMSE of 2.43 mg m^-3, and mean bias of 3.46 mg m^-3. As a result of applying the new empirical formula to hyperspectral and satellite images, the average RMSE between hyperspectral imagery and the measured CHL was 0.12 mg m^-3, making it possible to estimate CHL with higher accuracy than multi-spectral satellite images. Through these results, it is expected that it is possible to provide more accurate and precise spatial distribution information of CHL in coastal areas by utilizing hyperspectral imagery.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.1-18
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• 2009

A series of three-dimensional numerical simulations using a generalized multidimensional hydrodynamic dispersion numerical model is performed to simulate effectively and to evaluate quantitatively impacts of urbanization on density-dependent groundwater flow and salt transport in a coastal aquifer system, Suyeong-Gu, Busan, Korea. A series of steady-state numerical simulations of groundwater flow and salt transport before urbanization with material properties of geologic formations, which are established by numerical modeling calibrations considering all the urbanization factors, is performed first without considering all the urbanization factors. A series of transient-state numerical simulations of groundwater flow and salt transport after urbanization is then performed considering the urbanization factors individually and all together. Finally, the results of both numerical simulations are compared with each other and analyzed. The results of the numerical simulations show that density-dependent groundwater flow, salt transport, and seawater intrusion in the coastal aquifer system are intensively and extensively impacted by the urbanization factors. Especially, these urbanization factors result in the changes of the total groundwater volume and salt mass in the coastal aquifer system. However, such impacts of each urbanization factor are not spatially uniform but locally different.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.265-275
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• 2012

As climate change is becoming a growing concern and the importance of water management is increasing, the retention of carbon and nutrients in wetland soils including inland and coastal area has become important. In this study, retention characteristics of organic matter and nutrients of coastal sediment and soils in different types of wetlands such as constructed wetland, natural (inland marsh, estuary, tidal flat) wetlands were investigated. A correlation analysis was also performed to understand the relationship among organic matter properties, nutrient concentrations and soil texture of wetland soils. The degree of retention of organic matter and nitrogen in wetland soils varied with the wetland type. Inland wetlands retain more nitrogen than estuary or coastal wetlands, and natural wetlands retain more organic matter and nitrogen than constructed ones. Coastal sediments in a bay area where seawater circulation is restricted have more nutrients than those in estuary or tidal flats where seawater circulates well. The results showed that the sediment chemical oxygen demand has a high correlation with the total organic carbon and the total nitrogen in the studied area.

• Journal of Environmental Health Sciences
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• v.47 no.5
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• pp.479-485
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• 2021

Background: Vibrio vulnificus has been frequently detected in seawater, fish, and shellfish mainly in the coastal areas of Chungcheongnam-do Province. Objectives: This study was conducted to investigate the analyzed biochemical properties, genetic characteristics, and distribution of Vibrio vulnificus isolated from environmental sources in coastal areas of Chungcheongnam-do Province from 2019 to 2020. Methods: A total of 1,510 samples were obtained from six different sites in Chungcheongnam-do Province. Isolated strains from the samples were identified by a VITEK 2 system and MALDI-TOF. Antibiotic susceptibility testing for 85 isolates was done by microdilution minimum inhibitory concentration methods, and 11 isolates were analyzed for 16s rRNA sequences in multiple alignments. Results: Among the 1,510 samples taken during the investigation period, 306 strains were isolated and the detection rate of V. vulnificus was 20.3%. One hundred eighty-eight strains (24.6%) from seawater and 118 strains (15.8%) from mud flats were isolated. It was mainly detected in July (17.3%), August (36.5%), and September (28.8%), and the proportion was 82.0%. Based on the CLSI-recommended breakpoints, V. vulnificus isolates were all susceptible to amoxicillin/clavulanic acid, amikacin, gentamicin, ciprofloxacin and trimethoprim/sulfamethoxazole. However, nonsusceptible isolates to ampicillin, ampicillin/sulbactam, cefazolin, cefoxitin, imipenem, tetracycline and chloramphenicol were identified. In the analysis of the nucleotide sequences for 16s rRNA of V. vulnificus isolates, it was confirmed that mutations frequently occurred between nucleotide number 922 and 952, and 98.2% to 100% nucleotide identities between isolates was verified. Conclusions: The results of this study can be used as a basic data for infection control and prevention of Vibrio vulnificus infection by describing the distribution and characteristics of Vibrio vulnificus strains isolated in coastal areas of Chungcheongnam-do Province.

• KCID journal
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• v.12 no.1
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• pp.28-37
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• 2005

Although experimental analysis for groundwater sample at wells located systematically are very effective to delineate seawater intrusion region at coastal area, this method is restricted in few wells and time. We have conducted electrical resistivity soun