• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.4
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• pp.3-22
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• 2000

To know characteristics of water quality in coastal sea around the Keum river estuary in summer, we studied the water quality of surface, middle and bottom level during Jun e～september, 1998. The mean concentrations of COD, DIN, DIP & chlorophyll-a were 1.36mg/L, 28.60㎍-at/L, 0.48㎍-at/L and 4.14㎍/L, respectively, which were over eutrophication criteria in sea water. After the Keum river dyke was constructed, seasonal freshwater discharge was largely changed. About 80% of total annual freshwater discharge was concentrated in summer as rainy season from July to September. The correlation coefficient of DIN versus salinity was shown to be high, and thus the concentration of DIN was closely related to freshwater discharge. Maximum Chlorophyll-a concentration was occurred in September, due to increased DIP concentration, high water temperature and low salinity after heavy rainfall in August. The results of Principal Component Analysis showed that the first factor represented a series of eutrophication factors, the second factor w3s a valiance of seasonal fluctuation, and the third was a variance of progress of mass change.

• Korean Journal of Environmental Biology
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• v.17 no.1
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• pp.51-58
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• 1999

To investigate the distribution of nutritive salts and organic compounds in six stations at the coastal area of East Sea, environmental factors, nutritive salts, organic matters and chlorophyll were analysed four times from July 1994 to April 1995. The value of BOD in Ulsan Chuyongam was the highest among 6 stations. The concentration of nutritive salts was generally high through the investigation period near Pohang and Ulsan Chuyongam. From the value of dissolved nutrient salts, the Chuyongam area seemed to be under hyper-eutrophication and the Changsengpo area under eutrophication. Suspended particulate matter (SPM) of 3~10${\mu}{\textrm}{m}$ in size was distributed up to 70% of total volume. The amounts of SPM and particulate organic matter (POM) were considerably high in Pohang and Ulsan, which seemed to be resulted from the input of pollutants of cities and factories nearby.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.1-10
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• 2000

A three-dimensional hydrodynamic-ecosystem model was developed and applied to Chinhae Bay which is located in the southeastern sea of Korea. The model includes a three-dimensional hydrodynamic model and an eutrophication model, and the model operates on the same grid system. The agreement between predicted and measured results is reasonably encouraging. The concentrations of the calculated COD, DIN and DIP are appeared to be very high due to the phytoplankton production and the wastewater input in the northern part of Chinhae Bay. Anoxic and hypoxic water masses in the bottom layer occur in the northern part of the bay due to the excess loading of wastewater and strong stratification, and in the western inner part of the bay due to high oxygen consumption in densely populated aquaculturing facilities. DO concentration contours show parallel to the bay entrance line, which means the importance of supplying DO by physical process from the mouth of the bay. Although both the hydrodynamic and biochemical processes play important role to form the hypoxic waters in the bottom of the inner bay, it is suggested that the hydrodynamic conditions such as the vertical and the horizontal eddy diffusivity are primarily important factors.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.1
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• pp.41-49
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• 1999

The horizontal two-dimensional model which can predict the long-term water quality(WQ) change is setup for the environmental management. For the model calibration and verification, we measured the pollutants load at 22 streams and the WQ at 16 stations monthly and/or seasonally in Chinhae . Masan Bay. The pollutants release rate from the sediment was also measured to consider the regionally different sediment pollution level. From the model application results, it is shown that the WQ concentrations in most of the regions adjacent to land and river inflow are considerably high, but rapidly decrease along the seaward direction. In Masan Bay, the particulate inflow-pollutants were substantially deposited and gradually contaminated the bottom sediment on account of the excessive pollutants load and flow stagnancy. Eutrophication in the effluent discharge region was also being slowly progressed by the inefficiently treated wastewater containing amount of Nand P constituents.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.95-100
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• 2006

Measurements of ocean color from space since 1970s provided vital information with reference to physical and biogeochemical properties of the oceanic waters. The utility of these data has been explored in order to map and monitor highly toxic/or harmful algal blooms (HABs) that affected most of coastal waters throughout the world due to accelerated eutrophication from human activities and certain oceanic processes. However, the global atmospheric correction and bio-optical algorithms developed for oceanic waters were found to yield false information about the HABs in coastal waters. The present study aimed to evaluate the potential use of red tide index (RI) method, which has been developed by Ahn and Shanmugam (2005), for mapping of HABs in Korean and neighboring waters. Here we employed the SSMM to remove the atmospheric effect in the SeaWiFS image data and the achieved indices by RI method were found more appropriate in correctly identifying potential areas of the encountered HABs in Korean South Sea (KSS) and Chinese coastal waters during 1999-2004. But the existence of high absorbing and scattering materials greatly interfered with the standard OC4 algorithm which falsely identified red tides in these waters. In comparison with other methods, the RI approach for the early detection of HABs can provide state managers with accurate identification of the extent and location of these blooms as a management tool.

• Journal of Environmental Science International
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• v.16 no.12
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• pp.1411-1424
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• 2007

Long-term trends and distribution patterns of water quality were investigated in the Asan coastal areas of Yellow Sea, Korea from 1975 to 2005. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids(SS), chemical oxygen demand(COD), dissolved oxygen(DO) and nutrients. Spatial distribution patterns were not clear among stations but the seasonal variations were distinct except COD, SS and nitrate. The trend analysis by principal component analysis(PCA) during twenty years revealed the significant variations in water quality in the study area, Annual water qualities were clearly discriminated into 4 clusters by PCA; year cluster 1988-1991, 1994-1997, and 1992-1993/1998-2005. By this multi-variate analysis we can summarize the annual trends as the followings; salinity, suspended solids and dissolved oxygen tended to increase from late 1980's, increased pH and COD from 1992, and decreased salinity and increased nitrogen and COD from 1990 due to the runoff frow agricultural lands causing eutrophication.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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• pp.270-276
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• 2014

Seasonal characteristics of water and sediment qualities and potential effects of the freshwater discharge from a small tide embankment interior in a coastal area in Goheung county were investigated from May to September in 2012. Chemical oxygen demand values (COD) were mostly higher than 2 mg/L in summer ebb tide, which exceed the standard value of water quality criteria II of acceptable level for aquaculture activities. Nitrogen and phosphorus were found as the limiting nutrients for algae growth in summer and fall and in spring, respectively. Nitrogen was the limiting nutrient for diatom growth in the whole studied period. The sudden high values of COD, ammonia, dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP) were found in water sample collected from station 5 which located in front of the tide embankment sluice gate during spring ebb tide. The freshwater discharge form the tide embankment interior maybe affected the survey areas during a short time interval. Mean values of eutrophication index of the surveyed coastal region in spring, summer and fall were all bigger than 1. Water quality was mostly considered at level II which acceptable for aquaculture activities. Sediment quality in this study was generally in the range of standard for fisheries environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.233-240
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• 1982

Some environmental parameters on the shell-fish farms in Deukryang and Gamagyang Bays during summer in 1981 were determined to find an eutrophication level for the conservation of the farm. Chlorophyll-a content in the seawater in the Deukryang Bay in September was $1.0{\sim}5.0{\mu}g/l$ with an average of $2.5{\mu}g/l$ In the superficial bottom muds, contents of COD were 5-10 mg/g, ignition loss $5-9\%$, phaeophytin pigment $2{\sim}5{\mu}g/g$, and sulfide 0.1-0.3 mg/g dry mud in both bays. High contents of both organic matters and sulfide were found in the innermost area of the Deukryang Bay and in the north western part of the Gamagyang Bay. All quantities including chlorphyll-a in the water are little less than or similar to those of Hansan-Geoje Bay, one of the most productive shellfish farms in the southern coastal waters in Korea . Eutrophication on both water and bottom mud was under way like other shellfish farms but pollution indices on the bottom mud calculated from the data of CODs and phaeophytin pigments shelved 6-11, which is much lower than those of Jinhae Bay and of the Hansan-Geoje Bay. This means that the bottom muds are in an early stage of eutrophication, unlike the Jinhae and Hansan-Geoje Bays though the water, similar to the other bays, shows a middle stage of eutrophication.

• Ocean and Polar Research
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• v.29 no.2
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• pp.135-153
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• 2007

Temporal (seasonal) and spatial distributions and variations of various physico-chemical factors (salinity, temperature, pH, DO, COD, SPM, POC, silicate, DIP, DIN) in surface and bottom waters were studied in the coastal environment with typical macro-tidal range and monsoonal weather condition, Gyeonggi Bay, west coast of Korea. Spacial distribution patterns of these factors were generally similar to each other, and appeared to be inversely related to the distribution pattern of salinity, suggesting that water quality of the study area was primarily controlled by the physical mixing process of Han-River freshwater with nearby coastal seawater. During flooding season, silicate- and nitrogen-rich Han River water directly flowed into offshore as far as $20\sim30\;km$ from the river mouth, probably causing serious environmental problems such as eutrophication and unusual and/or noxious algal bloom, etc. Except the surface water during summer flooding season, high concentrations of nutrients appeared generally in dry season, whereas low values in spring, possibly because of the occurrence of spring phytoplankton bloom. On the other hand, nutrient flux through the estuary seems to be primarily depending on river discharge, sewage discharge and agricultural activities, especially during the rainy season. Also, nutrients in this coastal waters are considered to be supplied from the sediments of tidal-flats, which developed extensively around the Han-River mouth, especially during fall and winter of dry and low discharge seasons, possibly due to the stirring of tidal flat sediments with highly enriched pore-water nutrients by storm. And also, COD and DIN concentrations in the study area consistently increased during the last 20 years, probably because of agricultural activities and increasing discharge of industrial and domestic wastes.

• ALGAE
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• v.22 no.3
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• pp.221-228
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• 2007

Frequent occurrences of green tides caused by Ulva species (Ulvales, Ulvophyceae) associated with eutrophication along enclosed coasts are currently causing environmental problems in coastal ecosystems. In addition, increasing intercontinental introductions of coastal marine organisms, including Ulva, are also a serious issue. However, due to the considerable morphological plasticity of this genus, the taxonomy of Ulva species based on morphological studies is problematic. Therefore, in order to elucidate the species diversity and seasonal changes of the dominant Ulva species in Mikawa Bay, central Honshu, Japan, we made seasonal collections of Ulva species at seven localities, and identified the dominant species using the ITS2 rDNA region sequences. We identified the following nine taxa as common Ulva species in the area: 1) Ulva pertusa Kjellman; 2) U. ohnoi Hiraoka et Shimada; 3) U. linza L.; 4) U. californica Wille; 5) U. flexuosa Wulfen; 6) U. fasciata Delile; 7) U. compressa L.; 8) U. armoricana Dion et al.; 9) U. scandinavica Bliding. Among the species, U. pertusa was most common and dominant from spring to summer, and U. ohnoi from autumn to winter. Ulva californica and U. scandinavica have not been reported before from Japan.