• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.178-184
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• 1998

To elucidate contamination levels and distribution of methyl mercury (Me-Hg) in Korean coastal areas, 126 sediment samples were collected from Kyeonggi Bay, Namyang Bay, Chinhae Bay, and Lake Shihwa during 1995-1996, and the Me-Hg concentrations were determined by cold vapor atomic fluorescence spectrometry (CVAFS). Contamination levels of Me-Hg in sediments from Kyeonggi Bay, Namyang Bay, Chinhae Bay, and Lake Shihwa were 274 ${\pm}$ 990, 108 ${\pm}$ 24, 294 ${\pm}$ 342, and 1080 ${\pm}$ 760 pg/g, respectively. Concentrations of Me-Hg in sediments were significantly correlated with total organic carbon and sulfur contents, but were independent of mud contents and mean grain size. The highest concentration of Me-Hg (7100 pg/g) was observed at Incheon North Harbor (Site Kl9) in Kyeonggi Bay. This Me-Hg concentration was one or two orders of magnitude higher than those in other Kyeonggi Bay sediments were. The average concentration of Me-Hg in sediments from Lake Shihwa was higher than in those from other study areas. The three peaks of Me-Hg concentrations were observed on three sites (55, 56,and 510) in Lake Shihwa and gradually decreased in distance-dependent manner around these sites. High concentrations of Me-Hg at surface and 10-cm sediment depth in Chinhae Bay maybe due to higher rates of methylation process by active sulfate-reducing bacteria or higher concentrations of total mercury available to sulfate-reducing bacteria.

• Journal of the korean society of oceanography
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• v.33 no.3
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• pp.64-70
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• 1998

Forty sediment samples from Kyeonggi Bay, Korea were analyzed for butyltins, including tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) to determine their distribution and source in this area. Total butyltin concentrations in Kyeonggi Bay sediments ranged from 0.8 to 297 ng/g dry wt. with a mean value of 38 ng/g. The highest butyltin concentration was found in the innermost site in Incheon Harbor basin. The mouth of Han River had higher butyltin levels in sediments compared to open ocean. Butyltin levels correlated well with organic carbon content of sediment, but the major factor was the distance from the source area where antifouling paints were used for vessels and marine structures. Butyltin concentrations in the study area were lower than those reported for bays in other parts of the world. Considering the high toxic potential and sediment/water partition coefficient of TBT, further studies are needed to assess its biological effect in the marine ecosystem of Kyeonggi Bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.243-250
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• 2003

The spatio-temporal distribution of zooplankton community was investigated in Kyeonggi Bay with monthly samples from February 2001 to December 2001 at 5 stations along a transect between Incheon coastal waters and Seongap-Do. Monthly mean abundance of total zooplankton ranged from 1,100(Feb.)∼404,200 indiv./㎥ (Aug.) and annual mean abundance of total zooplankton was 55,000 indiv./㎥. The spatial mean abundance of total zooplankton varied from 114,600 indiv./㎥ (Incheon coastal waters) to 16,500 indiv./㎥ (Seongab-Do). Zooplankton abundance was higher in the inner bay than in the outer bay. Noctiluca scintillans, Acartia hongi, Oithona davisae, Paracalanus crassirostris, Paracalanus indicus and Oikopluera spp. were dominant species in Kyeonggi Bay and they contributed 95％ of annual mean abundance of total zooplankton. Most of dominant species distributed widely in study area throughout the year, however seasonal abundance peak only happened in inner part of the Bay. This pattern suggests that the spatio-temporal distribution of zooplankton is affected by the variations of water temperature and phytoplankton standing stock.

• 한국해양학회지
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• v.27 no.4
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• pp.277-289
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• 1992

Kyeonggi Bay, a macrotidal coastal embayment in the Yellow Sea coast of central korea, is fringed by vastly developed tidal flats. About 400 surface sediment samples were collected from the intertidal and subtidal zones of Kyeonggi Bay for a study of the sediment distribution pattern and the surface sediment characteristics of this environment. The kyeonggi Bay surface sediment becomes progressively finer in the shoreward direction, from offshore sand to shoreward silty sand and sandy silt. This shoreward-fining trend is repeated again on the tidal flat and, as a consequence, a grain-size break occurs near the low-water line which separates the intertidal area from the subtidal one. The intertidal and subtidal sediments differ from each other in textural characteristics such as mean grain size and skewness and this can be interpreted to result from differences in hydraulic energy and morphology between the two environments. The mineral and chemical compositions of the Kyeonggi Bay sediments are largely controlled by the sediment grain size. Smectite was nearly absent in the clay mineral assemblage of Kyeonggi Bay sediment. The contents of Co, Cu and Ni were high in the Banweol tidal flat, which suggests a continuous process of accumulation of these metals. the intertidal environment appears to respond rapidly to artificial coastal modifications, the effects of which should be taken into consideration when planning a dam construction or coastal reclamation.

• 한국해양학회지
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• v.27 no.2
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• pp.164-172
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• 1992

This study was carried out to investigate the benthic polchaete community in the southern area of Kyeonggi Bay, Korea. The species composition was examined in Asan Bay in 1985, the coastal area near Yibug in 1987, the area between Daeranjido and Asan Bay for 1988-1989, and the offshore south of Deogjeogdo in 1992. Polychaetes, the dominant faunal group occupying 57.4% in total density, comprised a total of 124 species with a mean density of 211 indiv.m/SUP -2/. The dominant polychaete was Prionospio sp. (28.8%), followed by Nephtys polybranchia (6.0%), Tharyx sp. (4.8%) Stermaspis scutata (4.4%), Lumbrineris longifolia (3.9%). The Number of species and density were higher in the coastal area near Yibug, Asan Bay and the mouth of Namyang Bay, while lower in the channels of offshore region. The cluster analysis revealed that the study area could be divided into 5 regions, which were distributed serially along the coast from Asan Bay to open sea. Each region sustained its specific Bay, Stermaspis-Heteromastus assemblage from Asan Bay to Daeranjido, Hemipodus assemblage in the channels of offshore, Lumbrineris assemblage on the coastal area o Yibug and Prionospio assemblage in the coastal area south of Yibug. Tharyx-Chone assemblage had the highest species number of 75 spp. and Prionospio assemblage had the highest density of 3,695 indiv.m/SUP -2/ due to the predominance of prionospio sp.. Hemipodus assemblage with the lowest density occupied the largest area in offshore region. The southern Kyeonggi Bay showed higher species number and lower density than the northern Kyeonggi Bay. But the dominant Polychaetes were similar between the southern Bay and the channel regions of the northern Bay.

• Journal of the korean society of oceanography
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• v.34 no.1
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• pp.36-42
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• 1999

To assess present status of polychlorinated biphenyls (PCBs) contamination in Kyeonggi Bay, Namyang Bay, and Lake Shihwa, 63 sediment samples were analyzed and applied to equilibrium partitioning approach. Sediment quality criteria (SQC) for exposure to Kanechlor mixture (KC-mix) was calculated as a value of 16 ${\mu}$g/g-organic carbon (OC). Two sites (Sites Kl8 and Kl9) within Incheon North Harbor (INH) with total PCBs concentrations 48 and 38 ${\mu}$g/g-OC, respectively, exceeded SQC, indicating a potential of adverse biological effects. The advantage and disadvantage of equilibrium partitioning approach has been discussed.

• Journal of the korean society of oceanography
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• v.34 no.2
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• pp.122-131
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• 1999

This study examined the relationship between the sediment pollution and the occurrence of polychaetes in a heavily polluted saltwater lake, Lake Shihwa on the west coast of Korea, separated from the sea by a dike in 1994. The species composition of polychaete assemblage was compared with that found off the lake in Kyeonggi Bay. Environmental variables investigated both in and off the lake were the grain size distribution, chemical oxygen demand(COD) and metal concentrations (Al, Fe, Mn, V, Co, As, Pb, Cr and Cu) in the sediment. We sampled sediments at 10 stations in the lake and 25 stations in Kyeonggi Bay using a modified van Veen grab. The levels of COD, chromium, and copper in sediments were much higher in Lake Shihwa than in Kyeonggi Bay. Differences in the species composition were found along the pollution gradient. An azoic zone was observed in the most heavily polluted area at the upper reach of the lake and the Polydora ligni zone in the center of the lake. Bottom fauna were diverse in Kyeonggi Bay; however, Heteromastus filiformis predominated in the organically enriched sediment. The density of dominant species differed along the pollution gradient. The highest density or H. filiformis was round at the COD level or around 5.8 mg/g. The COD level in the sediment where P. ligni predominated was tow-fold higher than that where H. filiformis occurred in large numbers. The chromium and copper contents at which P. ligni showed a maximum abundance were 120 mg/kg and 127 mg/kg, respectively. The density of H. filiformis was highest at concentrations of 56 mg/kg chromium and 13 mg/kg copper.

• Journal of the korean society of oceanography
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• v.36 no.1
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• pp.9-18
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• 2001

Chemical speciation of five heavy metals (Cr, Cu, Ni, Pb, Zn) has been analyzed from 37 surface and 2 core sediments of Kyeonggi Bay, using the modified sequential extraction method based on Tessier et at. (1979). The results show that heavy metals in the Kyeonggi Bay surface sediments are associated dominantly with the crystal lattice fraction. But in the polluted sediments of the Incheon North Harbor, the importance of the labile fractions increased while that of the lattice fraction decreased. In particular, the adsorbed and the easily reducible fractions showed a noticeable increase. In the core samples emerged a speciation pattern which differed significantly from that of the surface sediments. A sharp increase in the percentage of the reducible and organic/sulfide fractions and a decrease in the lattice fraction were observed. Throughout the vertical column, however, the metal contents in the lattice fraction showed stability while those of the labile fractions showed an upward increase. The strong association of heavy metals with the organic/sulfide fraction could be attributed in part to the sulfate reduction prevailing in the polluted harbor sediments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.261-270
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• 1998

This study was carried out in order to investigate the distribution and species composition of benthic polychaetous community in northern Kyeonggi Bay in September 1995. Mean density of benthic animals was 557 indiv./$m^2$. Benthic polychaetes were the most dominant faunal group, comprising 60 species with a mean density of 488 indiv./$m^2$. Benthic polychaetes were most abundant in Yumha Channel centering on Incheon Harbor, whereas relatively poor in the intertidal zones fringing Yongjong Island and Songdo area, and in the offshore main channel. The most dominant polychaete was Heteromastus filiformis (47.3% of polychaetous community), followed by Nephtys palybranchia, Tharyx sp., Sternaspis scutata and so on. Kyeonggi Bay could be divided into 4 regions from cluster analysis based on the dominant species composition: offsea/channel region, Incheon Harbor, intertidal zone of Yongjong Island, and intertidal zone of Songdo area. Highest species number and diversity index (H') were recorded at offsea/channel region, whereas highest faunal density at Incheon Harbor. Incheon Harbor was characterized by high abundance of H. filiformis. Compared with the previous studies carried out in Kyeonggi Bay, faunal density and species number have little changed for the recent 10 years. Dominant species was different between each study, but has been among opportunistic species of small-sized polychaetes belonging to capitellids, cirratulids or spionids. These results indicate that Kyeonggi Bay has been organically polluted steadily; specifically, this study reveals that Incheon Harbor has been the center of pollution and that the benthic community in the outer sea off Sihwa dike has become unstable.

• Korean Journal of Microbiology
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• v.28 no.4
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• pp.324-330
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• 1990

The distribution of physicochemical environmental factors and microbiological factors was studied at 6 sampling sites in Kyeongge Bay of Yellow Sea from October 1989 to October 1990. The total bacterial number, saprophytic bacterial number, petroleum-degrading bacterial number, bacterial biomass, and bacterial secondary production were measured in the range of 0.09~1.24*10$^{7}$ cells/ml, 7~60000 CFUs/ml, 0~240 cells/ml, 14.16~301 .$\mu$g-C/l, and 0.13~11.82 mg-C/m$^{3}$/hr, respectively. The turnover times of $^{3}$H-glucose and $^{3}$H-acetate were in range of 6.5~6984 and 41~24897 hours, respectively. The spatial distribution of heterotrophic bacterial communities were hightly affected by influx of organic pollutants from the coastal area and the seawater exchange with offshore.