• Journal of Korean Port Research
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• v.13 no.1
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• pp.123-132
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• 1999

It is very important to quantitatively assess the movement of sea water and pollutant dispersion before or after constructing shore structures such as breakwater considering marine environment and long-term utilization of those structures. This assesment is possible through the use of simulation models designed to predict water movement and pollutant dispersion in a certain area. In this study the numerical computations were carried out to predict the sea water quality in the Ilgwang Harbor located at the east coast of Pusan. The flow patters were investigated before and after the development of Ilgwang Harbor. The computational models adopting ADI Method (Alternating Direction Implicit Method) were used here and were already verified from the previous studies. As a results of this study the tidal exchange in Ilgwang Harbor after development proved to be worse due to the increased semi-enclosed at the harbor limit. In order to improve the water quality of this area after development a new method was proposed to improve water quality in the semi-enclosed bay by creation and control of tidal residual currents. For this purpose the unsymmetric structures so called bottom roughness were introduced in this study. The simulation was carried out on the basis of the study by Komatsu et. al. and Gug and we made a conclusion that it is possible to generate a new tidal residual current and to increase the tidal exchange by application of bottom roughness arrangement.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.399-412
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• 2005

This study investigated the composition and the distribution of the benthic polychaeta community in the semi-enclosed Yoja Bay on the southern coast of Korea and was designed to deduce temporal changes in the community with the comparison of the previous studies. In YoJa Bay, benthic polychaetous community structure was investigated on the base of the samples from 87 stations. The surface sediment was mainly composed of fine-grained sediment, mixed clayey silt and silty clay. The total benthic macrofaunal density was $387 indiv./m^2$, and the density was higher in the middle bay, and in the mouth of bay than in the inner bay. scapharca subcrenata (Bivalvia) and amphipods (Crustacea) were important species in the inner and the middle of the bar, respectively. Benthic polychaetes were comprised of 72 species with a mean density of $149 indiv./m^2$. Their distributions showed higher densities in the mouth of bay than in the rest of bay. The dominant species over 1.0 percentages were composed of the 20 species, and they occupied $84.5\%$ of the total density. The most dominant species was Sternaspis scutata ($13.6\%$), fallowed fly Heteromastus filiformis ($9.8\%$), Polynoidae indet. ($8.3\%$), Sigambra tentacuzata ($7.1\%$) and others. The cluster analysis revealed that the study area was divided into three station groups. At the station group YI located in the inner bay, the most dominant species was Heteromastus filiformis . At the station group YII in the middle bay, the dominant species was Sternaspis scutata. And at the station group YIII in the mouth of bay, the dominant species was Paraiacydonia paradoxa. Whereas Sternaspis scutata and Mediomastus sp. were the dominant species in the past study, Heteromastus filiformis and Tharyx sp. appeared newly to be the dominant species, even if their low densities that in the past. These facts mean that Yoja Bay be maintained yet as little polluted area compared to other bays on the coast of Korea, but needed some caution of marine environmental management.

• Environmental Engineering Research
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• v.21 no.4
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• pp.373-383
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• 2016

Cheonsu Bay, one of the most important in Korea as a coastal fishery is a semi-enclosed bay that is surrounded by large farmlands and industrial areas. This coastal environment has been affected by anthropogenic pollutants, such as polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). The objectives of this study were to investigate the distribution of PCBs and OCPs in sediment, Manila clams, and mussels from Cheonsu Bay; the accumulation pattern of these chemicals in these bivalves in relation to seasonal changes; and the ecological risk from sediments and the risk to the Korean population from the consumption of these bivalves. The levels of ${\Sigma}PCBs$, ${\Sigma}DDT$, and ${\Sigma}HCHs$ were 69.3-109, 40.3-49.3 and 6.25-17.8 ng/g lipid in Manila clams, and 70.6-159, 38.6-102 and 9.00-13.5 ng/g lipid in Mussels. Significant seasonal variations in PCBs and OCPs concentrations were observed in the two bivalves, suggesting that the accumulation of PCBs and OCPs in these species is related to their spawning times. The dietary intake of these two bivalves and the resulting lifetime cancer risk (LCR) and non-cancer risk were calculated for the human population. The consumption of these bivalves seemed to be safe in relation to human health with negligible LCR and non-cancer risk.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.303-312
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• 1998

It is necessary to quantitatively asses the influence of tidal currents to analysis the coastal current patterns before or after constructing offshore structures like as breakwaters. This assesment can be made through the use of simulation models designed to reproduce the water movements of the area. And it is very important to predict a phenomenon of pollutant dispersion in the area. In this study, in order to predict the changes of sea water quality for the port development plan, Ilgwang harbour, located at the east coast of Pusan, the numerical computations were carried out. The flow patterns were investigated before and after the development of the harbour bay and coastal area connected on it. The computational models are an extension of earlier work on the flow which used the ADI Method (Alternating Direction Implicit Method) in appling to Osaka Bay by KANEKO et al. The transport of pollutant constituents depends upon the currental characteristics of the water-transporting medium. In the currental flow model, water velocities and water levels are computed throughout the regions of it. These value are then used in the mass-balance equation to obtain the pollutant-constituent transport. As a result of this research, the present water quality of Ilgwang harbour and the coastal areas connected on it was proved out some good condition. The changes of sea water quality due to the port development plan of the Ilgwang habour bay and the coastal area were not large compared with the present condition, but it will be likely able to get worse by increasing the semi-enclosed areas in the harbour bay. In order to improve the water quality of the area after development, the method to activate tidal exchange in the area can be needed, as a mitigation technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3279-3285
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• 2014

This study aimed to understand seasonal and geographical characteristic of chlorophyll-${\alpha}$ (chl-${\alpha}$), COD (chemical oxygen demand) and Escherichia coli at Gwangyang Bay during the period from February 2010 to November 2012. The bay is divided into three different zones based on the pollutant levels and geographical characteristics. During the study periods, water temperature, salinity, Chl. ${\alpha}$, and chemical oxygen demand (COD) varied in the range of $4.68-28.63^{\circ}C$, 1.94-33.84 psu, 0.31-35.10 ${\mu}gL^{-1}$, and 0.70-13.35 $mgL^{-1}$, respectively. Total chl-a concentration were high at the zone I, which can be characterized as a semi-enclosed eutrophic area, and it were low at the zone III, which is influenced by low nutrients of surface warm water current from offshore of the bay. The high concentration of COD was observed at inner bay during the four seasons and the water quality level was kept to be bad condition during spring season at the zone II, which is influenced by Seomjin River water. The highest colony form of E. coli was recorded to be 3550 $cfuL^{-1}$ during summer at station 1 (zone I), whereas it was relatively kept low level during all seasons at the zone III. As a result, the E. coli was correlated with water temperature (r=0.31 p<0.05) and salinity (r=-0.55 p<0.05), implying that those parameters have play an important crucial role in proliferation of E. coli. Consequently, our results indicated that the E. coli can be significantly promoted within pollutant sources including the high nutrients supplied by rive discharge during spring and summer rainy seasons in semi-enclosed area of Gwangyang Bay.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.1
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• pp.1-12
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• 2007

Mooring survey for measurement of tidal current and suspended sediments was carried out at 4 inlets of Yeoja Bay in April, 2000 in order to understand the source of sediment supply. Net suspended sediment transport load during 2 tidal cycles through the M-1(West Inlet) was $133.88\;kg{\cdot}m^{-1}$ toward the Yeoja Bay, whereas the flux through the M-2(Jabal Inlet) was outward the Bay with the amount of $146.43\;kg{\cdot}m^{-1}$. The influx through the M-3 and 4(Bulgyo and Dong Isa Stream) was $23.25\;kg{\cdot}m^{-1}$ and $4,312.31\;kg{\cdot}m^{-1}$ toward the Yeoja Bay, respectively. Influx of suspended sediment on Yeoja Bay mainly occurred in the Dong Isa Stream. In the wet season the composition of surface was coarser-grained than dry season, possibly due to the influx of silty sediment from Dong Isa Stream In the wet season.

• 한국해양학회지
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• v.26 no.3
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• pp.204-222
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• 1991

The annual cycles of plant major nutrients and dissolved oxygen in a nutrients-rich semi-enclosed coastal inlet, chinhae Bay, of the southern coast of the Korean Peninsula are first presented. The water column of the bay is stratified during summer (April-late September) and well0mixed during winter (October-March). During the summer stratification period, dissolved oxygen contents exceed 400uM in the surface but diminish to less than 50uM in the near bottom waters, which often results in an anoxic environment in the inner part of Chinhae Bay. After the breakdown of the stratification in October, dissolved oxygen concentration remains undersaturated until February. The evidence of allochthonous input of N-nutrients throughout the year is readily seen in the water column: however. crude budget calculations show that the nutrients are efficiently utilized within the bay ecosystem, and that export of the nutrients from the bay to the shelf must be negligible. There is no sign of the enrichment of the nutrients in the water column. The eutrophication phenomenon sensu stricto is not observed in chinhae Bay. Using the standing stock of dissolved oxygen and estimation of the oxygen fluxes across the air-sea boundary, a benthic oxygen respiration rate during winter is estimated conservatively at 21-24 mmol Cm/SUP -2/d/SUP -1/. this oxygen respiration rate accounts for about 20% of the total phytoplankton production in winter.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3345-3350
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• 2014

We investigated to assess the relationships between the major nutrients and phytoplankton dynamics during the spring season in 2010 and 2011 at 23 stations in Jinhae Bay, Korea. The bay is divided into four different zones based on pollutant sources and geographical characteristics. Nutrient limitation (>80%) was significant in Zone II, which is located in central bay and is influenced by the water well mixed from outer bay. The limited nutrient was followed in Zone III and IV that was occupying between 17% and 83%. However, the low levels are being kept below 35% in Zone I, which is characterized by the semi-enclosed eutrophic area of Masan and Haegam bays. Based on the PCA (principle component analysis) analysis, the nitrogen (N) sources in 2010 were particularly dominant and it may be due to the water mixing and wastewater formed from bottom layers and sewage. In 2011, major nutrients including nitrogen, silicon and phosphorus were dominant in the bay and are supplied by the river discharge after rainfalls with low salinity conditions. In particular, the N nutrients being supplied in 2010 are correlated with pennate diatoms Pseudo-nitzchia spp. and is not related to the phytoplankton population densities in 2011. The present study suggests that N sources play an important role in the proliferation of diatom, and the rapid nutrient uptakes by them are potential nutrient limitation factors in the bay.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.320-332
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• 1999

Investigations were made on the community structure of macrobenthos in the subtidal soft bottom around semi-enclosed Youngsan River estuarine bay, southwest coast of Korea during the period from April 1995 to February 1996. Three macrobenthos samples were collected at 40 stations using a van Veen grab(0.1 m^2) during the study period. A total of 206 species of macrobenthos was identified. Their mean density and biomass (wet-weight, wwt) were $1,137 ind./m^2$ and $65.28 gwwt/m^2$, respectively. Of these, there were 74 species of polychaetes ($36\%$), 60 molluscs ($39\%$), 51 crustaceans ($25\%$) and 21 miscellaneous taxa. Molluscs were represented as a density- and biomass-dominant faunal group with a mean density of $601 ind./m^2$($53\%$ of the total benthic animals) and biomass of $25.37 gwwt/m^2$($39\%$ of total biomass): It was followed by polychaetes with $405 ind./m^2$($40\%$ of the total density). Total number of species and diversity were Bow in the inner estuarine bay containing high mud content and organic matter, whereas they were high in the outer stations containing low mud content and organic matter. Major dominant species were one biralve, Theora fragilis and three Polychaetes, Tharyx sp., Poeciloceatus johnonni and Lumbrineris lontifolia whose mean densities were $490ind./m^2$, $96ind./m^2$, $74ind./m^2$and $52 ind./m^2$, respectively. Cluster analysis indicated that the study area could be divided into four station groups: two innermost station groups, a central bay and an outer station group. The species diversity increased from the inner station group toward the outer groups. These results were discussed in terms of both the environmental factors and distribution of benthic community.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.169-176
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• 2000

This study was carried out to clarify the spatial and temporal patterns of macrobenthic assemblages on the subtidal area around Mokpo, southwest of Korea. A total of 238 species and 663 ind./$m^{2}$ were collected. Polychaetes were the most abundant faunal group that comprised 88 species and had a mean density of 389 ind./$m^{2}$. In the semi-enclosed Youngsan River estuarine bay and neighbouring Mokpo Port area were composed of fine sediments with high organic content, and revealed large seasonal variations in the salinity of surface water and bottom dissolved oxygen in contrast to little seasonal changes in those parameters in the outer area. The study area was classified into four station groups by the cluster analysis; the harbor area, the offshore area, and the inner and outer estuarine bay. Two estuarine bay areas showed different species composition; the dominant species of inner bay were Tharyx sp., Poecilochaetus johnsoni, Heteromastus filiformis and other opportunistic species whereas those in the outer bay were Ruditapes philippinarum, Corophium sinense. From the environmental data and species composition of benthic community, the inner bay was characterized to have unstable benthic faunal assemblages, especially under the seasonal disturbance and receiving large amount of organic matter input and intermittant discharge of fresh water. The coastal developments around Mokpo city also seem to have stressed the subtidal communities spatio-temporally.