• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.178-185
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• 2013

We measured salinity and $^{222}Rn$ concentration to explore submarine spring along the coastal areas (Mundongri, Icheon-ri, Jukseong-ri, Daebyeon-ri, Yeonhwa-ri, and Dadae-po) including Ilkwang Bay of Busan Metropolitan City in 2009 and 2010. Before field observation, we selected the potential and possible locations of submarine spring based on the lineament distribution and rose diagram analysis. Salinity and radon concentration were measured within the 1~2 km from the coastal lines. Radon activity decreased gradually from onshore to offshore. Vertical profiles of salinity at some stations showed lateral transport of water mass characterized by low salinity. Vertical profiles of salinity in the Ilkwang Bay, which is a unique bay in the south-eastern coastal area of Busan Metropolitan City, also showed the occurrence of low salinity in the bottom seawater. Our results suggest the possible occurrence of submarine discharge of fresh groundwater in the coastal areas around Busan Metropolitan City. In the future, intensive research should be conducted for the exploration methods of submarine spring as well for the possible utility of submarine groundwater as alternative water resources.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.4
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• pp.173-193
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• 2022

Dissolved nutrients in seawater are a key variable for understanding the role of the ocean in controlling atmospheric carbon dioxide, which is a major cause of global warming. In order to continuously monitor changes in the marine environment in the waters around the Korean Peninsula, dissolved nutrient data are being measured through regular observations by national institutions and various research projects. To increase the utilization of these data, the Jurisdictional Ocean Information Sharing System (JOISS), which integrates data from each institution, was established. In this study, for the dissolved nutrient data of JOISS, primary quality control was performed using the regional dissolved nutrient concentration range in the waters around the Korean Peninsula, and the correlation between the dissolved nutrient and other oceanographic characteristics or the correlation within dissolved nutrient components. Providing the quality control flags of regional range and primary quality control may increase the reliability of JOISS dissolved nutrient data and promote the utilization of dissolved nutrient data in JOISS. In addition, we proposed a secondary quality control method essential for improving the international comparability of JOISS dissolved nutrients.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.41-50
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• 2023

Dissolved oxygen sensors have characteristics in which data drift occurs over time. Therefore, in-situ calibration of the dissolved oxygen sensor is essential to accurately measure the concentration of dissolved oxygen in seawater. In order to provide a method for in-situ calibration, appropriate number of samples for calibration, and laboratory calibration interval of the dissolved oxygen sensor, the dissolved oxygen sensor values were compared with the measured values by titration on a total of 133 samples from three different cruises in the Indian Ocean, Pacific Ocean, and East Sea over a period of about one year. As a result, it is preferable to calibrate the sensor value using the correlation of a straight line obtained by directly comparing the final concentration value given by the sensor and the measured value. For the accurate calibration, at least 30 samples must be used to enable in-situ calibration within an accuracy range of about 1%. In addition, it is recommended that a laboratory calibration should perform within 1 year for the membrane type dissolved oxygen sensor for CTD to achieve a performance of 70% or more.

• Analytical Science and Technology
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• v.22 no.5
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• pp.360-368
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• 2009

Tributyltin (TBT) use has been prohibited by the IMO (International Maritime Organization), as well as Korea, since 2003. This prohibition has affected a gradual reduction in TBT use in maritime environs (seawater, sediment, and biosamples) in several countries. In this study, Crassostrea gigas (oyster) and Tapes philippinarum (manila clam) were chosen and measured for butyltin compound concentrations to verify TBT pollution levels since its 2003 ban. Specimens were taken directly from farms for concentration measurement, where Crassostrea gigas and Tapes philippinarum are cultivated, as well as prevalent locations predicted to have been polluted. Concentrations of MBT, DBT, and TBT of Crassostrea gigas were measured to be N.D -N.D., N.D. -N.D., and N.D. -60.21 ng Sn $g^{-1}$ (wet wt), respectively. Regarding Tapes philippinarum, MBT, DBT, and TBT were N.D. -12.27 ng Sn $g^{-1}$ (wet wt), N.D. -45.95 ng Sn $g^{-1}$ (wet wt), and N.D.-7.30 ng Sn $g^{-1}$ (wet wt), respectively. For this research, a correlative study was conducted to determine butyltin compound concentration in Crassostrea gigas at the locations where measurements were made in 1994 to determine to what extent TBT pollution level decreased. A decrease in all 7 sites was observed. In 4 of the 7 samples, butyltin compounds were measured to be below the detection limit, while that of the Tapes philippinarum did not appear high compared to foreign research data.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.3
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• pp.115-123
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• 2010

The occurrence and variation of oxygen deficient water mass (ODW) in Namdae stream estuary, Yangyang were studied. Field observations for water properties and sediment environments were conducted at 5 stations of the estuary from April 2008 to November 2008. The coastal sandbar is developed at the estuary mouth, and there is a pool between the estuary mouth and about 2.3 km upstream of the estuary. The pool is relatively deep and narrow compared to riverbed of the estuary. The ODW was observed continuously in the pool from May to October. The ODW extends vertically up to 2 m depth in August, and maximum length of the ODW were about 2.3 km. Mean concentration of ignition loss (IL) and acid volatile sulfide (AVS) of sediment was 7.5~9.0%, $0.282{\sim}1.106\;mg/g{\cdot}dry$ wt, respectively. Ammonium concentration in the bottom layer during formation period of the halocline and the ODW was 4~23 times higher than that of surface layer. ODW was initiated by the introduction of seawater into bottom of the estuary pool to make a strong halocline, and then decomposition of organic matter within sediment accelerated the formation of the ODW.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.77-93
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• 2000

Field survey on the spatio-temporal distribution of water quality and chlorophyll a concentration, and the environmental factors on the variation of phytoplankton biomass were carried out at the 23 stations for four seasons in the Shiahae, southwestern coast of Korean Peninsula from February to October in 1995. I made an analysis on biological factor as chlorophyll a concentration as well as environmental factors such as water temperature, salinity and nutrients; ammonia, nitrite, nitrate, dissolved inorganic nitrogen, phosphate, N/P ratio, silicate and Si/P ratio. The waters in the Shiahae were not stratified due to the tidal mixing and high velocity of tidal current. And the high productivity in photic layer were supported by high nutrients concentration from freshwater on lands and bottom waters The low depth of transparency in the Shiahae had a bad influence upon primary production and marine biology. In Shiahae had a sufficient nutrients for primary production during a year. Especially dissolved inorganic nitrogen and silicate were high, the other side, phosphate was low. The source of nutrients in summer and silicate supply depend on input of freshwater from lands, the other side, dissolved inorganic nitrogen and phosphate were depend on rather supplied from bottom layer by the mixing and input of seawater from outside than input of freshwater from lands. Phosphate seemed to become a limiting nutrient for the primary production at all area of Shiahae in winter and at the northern parts in other seasons. However, dissolved inorganic nitrogen seemed to do it at the southern parts in other seasons except winter. Silicate didn't become a limiting nutrient for diatoms in Shiahae. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round, it was controlled by the combination of the several environmental factors, especially of nitrogen, phosphorus and the physical factors such as light intensity. [Spatio-temporal distribution, Seasonal fluctuation, Nnutrients, Chlorophyll a, Environmental factors, Nutrient source, Limiting Nutrient, Light, Shiahae] .

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.289-299
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• 2011

We studied the characteristics of pollutant concentrations in 9 streams that flow into Shihwa Lake in order to provide the scientific data for effective implementation of total pollution loads management system (TPLMS) of the Lake. Suspended solid (SS), chemical oxygen demand (COD), dissolved nutrients ($NO_2$, $NO_3$, $NH_4$, $PO_4$ and $SiO_2$), total phosphorus (TP) and total nitrogen (TN) in stream water from industrial complexes, urban and agricultural regions were determined. Pollutant concentrations in December were higher than that in other sampling periods. COD concentration from industrial complex region with average of 12.6 mg/L was 2 times higher those from urban region (6.6 mg/L) and agricultural region (5.9 mg/L). TP concentration from industrial region also showed higher concentration than other regions. TN concentration in stream water was 5.89 mg/L for industrial region, 3.02 mg/L for urban region and 5.27 mg/L for agricultural region, respectively, suggesting inflow of TN due to fertilizer usage in agricultural field. Relative percentage of nitrogen compounds in TN follows the sequence: $NH_4$ (35.1%) > $NO_2$ (20.0%) > DON (22.8%) > PON (8.9%) > $NO_2$ (3.2%). Concentrations of dissolved nutrients, TP and TN in stream water were 3.2~37.2 times higher than that in Shihwa Lake seawater, therefore large amount of pollutants may be directly entered into Shihwa Lake without any treatment. For Gunja stream of industrial region, pollutants at midstream showed relatively higher concentration compared to upstream and downstream. It is necessary to manage the illegal discharging of sewage and waste water. Our results provide valuable informations on the estimation and reduction of total pollutant loads in the process of establishing adequately strategic and implemental plan of Shihwa Lake TPLMS.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.5
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• pp.603-613
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• 1996

Hydrographic conditions (temperature, salinity, dissolved oxygen), nutrients, chlorophyll-a and suspended solid have been studied in the southwestern coastal area of Cheju Island from April 1993 to March 1994. Vertical profile of temperature, salinity and chemical properties (nutrients, chlorophyll-a) distribution in th southwestern sea of Cheju Island showed a upwelling feature. Although it was not clear in winter season, it seems to continued through out the year. In the surface water at the upwelling areas, the ranges of dissolved oxygen, nitrate, phosphate and silicate was $3.30\~8.43\;ml/l,\;0\~7.12{\mu}g/l,\;0.03\~1.75{\mu}g-at/l\;and\;2.75\~22.32\;{\mu}g-at/l$l, respectively. Nutrients was higher in the shore water than in the offshore water, because sufficient supply of nutrients from the bottom water by coastal upwelling. In November, especially high concentration silicate was observed at all the stations and depth in the study area. At all station of bottom water (down to the depth of 60 meter), concentration value of dissolved of gen was as high as 8 ml/l. Mean values of N/P was 8.0, lower than Redifield ratio of 16. The mean values of Si/P was observed to 46.3 in southwest of Cheju Island. Concentration of chlorophyll-a was in the range of $0.04\~2.36\;{\mu}g/l$. Concentration of chlorophyll-a in surface orator at all station was especially higher in spring than in other seasons. Mean concentration value of suspended solids was 3.14 mg/l $(0.75\~8.47\;mg/l)$. Ratio of the volatile suspended solids to the suspended solids was higher in the inshore water $(53\%)$ than in the offshore water $(46\%)$, and higher in the surface water than in the bottom water.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.8-15
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• 2010

An experiment was conducted to evaluate the biologically adverse effect of increased carbon dioxide in seawater on marine bacteria, Vibrio fischeri. We measured the bioluminescence and cell density at every 6 hours for 24 hours of the whole incubation period after exposing test microbes to a range of $CO_2$ concentration such as 380(Control), 1,000, 3,000, 10,000 and 30,000 ppm, respectively. Significant effect on relative luminescence(RLU) of V. fischeri was observed in treatments with $CO_2$ concentration higher than 3,000 ppm at t=12 h. However, the difference of RLU among treatments significantly decreased with the incubation time until t=24 h. Similar trend was observed for the variation of cell density, which was measured as optical density using spectrophotometer. The results showed that a significant relationship between $CO_2$ concentration and bioluminescence of test microbes was observed for the mean time. However, the inhibition of relative bioluminescence and also cell density could be recovered at the concentration levels higher than 3,000 ppm. The dissolved $CO_2$ can be absorbed directly by cell and it can decrease the intracellular pH. Our results implied that microbes might be adversely affected at the initial growing phase by increased $CO_2$. However, they could adapt by increasing ion transport including bicarbonate and then could make their pH back to normal level. Results of this study could be supported to understand the possible influence on marine bacteria by atmospheric increase of $CO_2$ in near future and also by released $CO_2$ during the marine $CO_2$ sequestration activity.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.4
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• pp.362-371
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• 2016

The distribution patterns of Chromophoric Dissolved Organic Matter (CDOM) and the chemical characteristics of CDOM in the Seomjin river estuary were investigated in March, June and July 2012 in order to determine the spatial and temporal variability of CDOM along the salinity gradient considering the effects of mixing, nutrients and Chl a. The average CDOM values were $1.0{\pm}0.3m^{-1}$, $1.3{\pm}0.4m^{-1}$, and $1.4{\pm}0.3m^{-1}$ in March, June and July, respectively. A high concentration of CDOM (greater than $1.5m^{-1}$) was found at the head of the river which decreased towards the river mouth to as low as less than $0.5m^{-1}$. The average concentrations of CDOM increased from the dry season (March and June) to the wet season (July), and the average slope values ($S_{300-500}$), which were used as indicators of CDOM characteristics and sources, were in the range of $0.013-0.018m^{-1}$. The CDOM and $S_{300-50}$ values showed that not only the concentration of CDOM but also the chemical properties of DOM clearly changed between upstream and downstream in the Seomjin river. CDOM and FDOM showed a negative correlation with salinity ($R^2$ > 0.8), and CDOM was positively correlated with FDOM. Furthermore, the mixing pattern of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM was confirmed as conservative for all seasons. The main environmental factors influencing the concentration of CDOM were salinity (mixing) and water temperature, which meant the dilution of low CDOM seawater, was the controlling factor for the spatial distribution of CDOM. Increases in water temperature seemed to induce the production of CDOM during summer (June and July) through the biological degradation of DOM either by microbial activity or photo-degradation.