• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.34-45
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• 2001

In the persent study, we conducted numerical experiments using a three-dimensional baroclinic equation model and a Lagrangian method for clarifying the hydrodynamics in Osaka Bay under the yearly mean discharge and visualizing the behaviour of particles of different settling velocity discharged from Yodo River and sedimentation pattern on the sea bottom. Particles are transported from the Yodo River to the south direction by the residual circulation of the bay head at the first stage, and after most of suspended solids particles are settled down at any layer and returned in the south-east coastal area through bottom layers by an estuarine circulation. The results show that estuarine circulation plays an important part of suspended solids transportation in the Osaka Bay.

• Journal of Environmental Science International
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• v.13 no.6
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• pp.561-570
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• 2004

This study was carried out to survey the pollution of nonylphenol (NP) in surface sediments around Gwangyang bay and Yeosu sound. NP was suspected chemicals as endocrine disruption. Gwangyang bay is located on the mid south coast of Korea. It is a semi-closed bay which Yeosu petrochemical industrial complex, POSCO (Pohang Steel Company) and Gwangyang container harbor are there. The surface sediments were collected at 15 stations with gravity corer at October, 1999, February, May and August, 2000. Also, the stream and intertidal sediment were collected at 5 sites at August, 2000. Concentrations of NP in surface sediments were in the range of 6.89 to 202.70 ng/g dry wt.. Seasonal range (mean value) of NP is 13.98 to 30.48 (23.46) ng/g dry wt. at October, 10.35 to 54.91 (28.10) ng/g dry wt. at February, 29.05 to 202.70 (82.32) ng/g dry wt. at May and 6.98 to 83.40 (25.37) ng/g dry wt. at August. NP was seasonally fluctuated, and the highest mean value and range was detected at May, 2000. NP was highly distributed in the inner part of Gwangyang bay than Yeosu sound. Concentrations of NP in stream and intertidal sediments showed the highest value in downstream near Yeosu petrochemical industrial complex and Yondung stream. It suggests that the source of NP is industrial wastewater and municipal sewage.

• Ocean and Polar Research
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• v.34 no.1
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• pp.1-18
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• 2012

We investigated seasonal changes in the mesozooplankton community structure in November 2006 and February, May, and August 2007 at 12 stations in the semi-enclosed Muan Bay, Korea. Forty taxa were sampled, with an average abundance ranging from 1,459 to 20,078 indiv. $m^{-3}$; the highest abundance was detected in August 2007, and the lowest in February 2007. Acartia omorii, A. hudsonica, A. ohtsukai, Bestiolina coreana, Calanopia sp., Paracalanus parvus s. l., Cirripedia larvae, Decapoda larvae, and Gastropoda larvae were the most abundant taxa detected. The species diversity of the mesozooplankton was high around the inner regions in August 2007 but it was relatively low in November 2006. Non-metric multidimensional scaling (nMDS) revealed significant differences in the structure of mesozooplankton community among the seasons. Canonical correspondence analysis (CCA), performed to examine the relationships among dominant taxa, stations, and environmental variables, showed that most species of copepods were positively correlated with temperature, salinity, chlorophyll a, and COD concentration. Our results suggested that the mesozooplankton community structure observed in this study might be affected partly by the seasonal changes in environmental variables, such as the status of the sluice gates (i.e., open or closed) and the in situ production of resting eggs by major copepods.

• 한국해양학회지
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• v.26 no.4
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• pp.304-312
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• 1991

The distribution of dinoflagellate cysts have been investigated at 6 stations in Masan Bay, a well known area of red tide in the southern coastal waters of Korea, from May 1986 to March 1987. During the study, a total of 11 species in dinoflagellate cysts were isolated from surface sediments, representing 6 genera, 9 species and 2 unidentified species. The standing crops of dinoflagellate cyst varied extensively by month and station; ranging from 48 to 1,279 cells/cm$^3$ and showing major peaks in July. August and February. At stations, the distribution was most abundant at st. 4 (mouth of the bay), whereas it was very low at st. 1 (inner bay), where motile cell's blooms occur throughout the year. Thus, It is speculated that the distribution between the plankton and cyst populations of dinoflagellates show the different temporal and spatial patterns in a semi-closed bay like this survey area.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.1
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• pp.36-44
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• 2015

The spatial and temporal distribution of dissolved trace metals has been studied to identify trends in space and time and to evaluate the pollution status in a semi-closed bay (Gohyun bay), Korea. Surface seawater samples were collected over four seasons at 18 stations in the bay between 2003 and 2004 and once at 7 stations around a large shipyard in May 2004. The concentration of Cd, Co, Cu, Ni, Pb, and Zn in seawater in February and May were highly variable in space, showing the higher value relative to other season. Those metals concentrations were decreased from inner-to outer-stations. In around the shipyard, Cu, Pb and Zn showed the higher variability depending on time. Cu and Zn concentrations at the sites around the shipyard had 2 times higher values compared with the average of inner stations in Gohyun bay. The very high correlations between salinity and either Cu and Zn has been showed. Especially, there was a significant relationship between Cu and Zn. We recognize that the shipyard is major source of Cu and Zn in seawater. Therefore, marine environment management policy such as the prevention and control of heavy metal input from a shipyard is required.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.2
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• pp.104-110
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• 2004

This study was carried out to survey the pollution of bisphenol A(BPA) and total organic carbon(TOC) in surface sediments around Gwangyang bay. BPA is suspected chemicals as endocrine disruption. Gwangyang bay Is located on the mid south coast of Korea. It is a semi-closed bay which Yeosu petrochemical industrial complex, POSCO(Pohang Steel Company) and Gwangyang container harbor are located. The surface sediments were collected at 15 stations with gravity corer at October, 1999, February, May and August, 2000. Also, the stream and intertidal sediment were collected at 5 sites at August, 2000. Concentrations of BPA in surface sediments were in the range of 0.46 to 24.59 ng/g dry wt.. Seasonal range(mean value) of BPA are 0.59 to 9.00(1.88) ng/g dry wt. at October, 0.99 to 2.97(1.57) ng/g dry wt. at February, 0.46 to 24.59(2.53)ng/g dry wt. at May and 0.54 to 2.46 (1.29)ng/g dry wt. at August. BPA was seasonally fluctuated, and the highest mean value and range were detected at May, 2000. BPA was highly distributed in the inner part of Kwangyang bay than Yosu sound. Concentrations of BPA in stream and intertidal sediments showed the highest value in downstream near Yochon petrochemical industrial complex and Yondung stream. It suggests that the source of BPA are industrial wastewater and municipal sewage. TOC in surface sediments were in the range of 0.09∼1.22%. There was no any correlation between the BPA and TOC.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.669-676
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• 2017

To understand the relationship between environmental factors and phytoplankton community structures and why early outbreaks of Cochlodinium polykrikoides occur in the inner bay of Korea, short-term investigations were conducted at 17 stations in the eastern part of the South Sea of Korea, with sessions every two weeks from July 7 to August 24, 2016. The water temperature increased from $22.3^{\circ}C$ in the first survey to $28.4^{\circ}C$ in the fourth survey, which was a rise of about $6.01^{\circ}C$. Salinity was relatively high at Stns. 8 13 in the inner bay. In the first survey, rainfall of about 150 mm was observed, so nutrients were supplied at a high level and a high concentrate of Chl. a was observed. Cryptophyta (Crpytomonas spp.) represented 58.3 % of the community, followed by Bacillariophyta at 33.8 %. In particular, at Stn. 5, Dinophyta Prorocentrum spp. accounted for a very high percentage, 32.2 %. In the second survey, low phytoplankton populations were observed, and Bacillariophyta (Chaetoceros spp.) accounted for 61.0 %. At Stn. 4, Skeletonema spp. showed high populations but did not appear at other stations even at a low density. In the third and fourth surveys, phytoplankton populations were very low. Bacillariophyta represented 78.0 % in the third study and 73.3 % in the fourth. Interestingly, although the appearance of C. polykrikoides was investigated at the beginning of the red tide in the coastal area, they were not observed inshore, implying that the likelihood of inflow by the germination of resting cysts was low for the inner bay during this study period. In addition, environmental characteristics such as salinity and nutrient presence were significantly different between sampling stations due to the existence of a semi-closed bay in the southern sea, resulting in dominant phytoplankton species and community composition differing in these short-term investigations.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.315-322
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• 2011

The importance of aquafarming is increasing all over the world, however the coastal environment in the semi-closed inner bay has been aggravated due to the long term production and the high stocking density. For the sustainable aquafarming, there is a requirement for a eco-friendly fishery management by the estimation of ecological carrying capacity. The model development and application is still in the initial step, because it has to consider the whole ecosystem and all culture activities. As an alternative, there is a requirement for ecological indicator to assess the ecological performance. This study tried the estimation of ecological carrying capacity using ecological indicator. The production and the facility of the oyster farms was 4,935M/T, $49ind./m^3$ in Geoje-Hansan Bay(2008). Filtration pressure indicator was 0.203 which could provide a guidance on the present level of culture development. According to the environmental characteristics and the present oyster farms in Geoje-Hansan Bay, the newly assessed filtration pressure for the acceptable ecological carrying capacity was 0.102. Consequently, ecological carrying capacity in Geoje-Hansan Bay was 2,480M/T, $25ind./m^3$ and this represents the level of culture that can be introduced into Geoje-Hansan Bay without leading to significant changes to ecological process, species, populations or communities. Our study utilized the ecological indicator to estimate ecological carrying capacity of oyster farming for sustainable productivity and this could be the scientific basis for the eco-friendly fishery management.