• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.1
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• pp.51-67
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• 2002

In order to understand behaviors of heavy metals around the artificial Lake Shihwa in the vicinity of Kyunggi Bay in Korea in relation with huge environmental changes due to construction of huge artificial lake, water samples were collected from Lake Shihwa and its tributaries from 1996 to 1998 and analyzed. Due to extreme pollutant discharge from various kinds of anthropogenic sources such as the Banweol and Shihwa Industrial Complexes and cities, the Shihwa and its tributaries have been polluted in waters with various heavy metals. The enrichment factors of particulate heavy metals in water of streams and storm sewers were very high. All of the heavy metals observed in the waters showed relatively high temporal and spatial variations. In surface waters of the lake during the desalination after the dike establishment, spatial distributions of heavy metal concentrations were mainly controlled by various biogeochemical factors as well as input of industrial and municipal wastewaters, while, physical mixing was minor factor Pb and Co showed a strong affinity to particle phase, however the affinity to dissolved phase was dominated in Ni, Cu and Cd. Water quality of the artificial Lake Shihwa has been deteriorated by direct discharge of untreated wastewater and heavy metals have been accumulated in the lake system. Therefore, luther environmental improvement plan should be programmed subsequently.

• Journal of Korean Society on Water Environment
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• v.34 no.2
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• pp.157-163
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• 2018

This study aims to determine the pollution levels of nine kinds of heavy metals (As, Cd, Cu, Cr, Hg, Mn, Ni, Pb, and Zn) in Lake Shihwa, which is susceptible to the inflow of pollutants, and the levels of heavy metal exposure in its fish and shellfish. Shihwa Lake's water quality did not exceed the short-term standard for protection of marine ecosystems, but concentrations of As, Cu, Cr, Hg, Ni, and Zn exceeded the long-term standard for protection of a marine ecosystem. In comparison to findings in prior research, performed in 2010, levels of Cr, Ni, As, and Zn are now 4.1 times lower. However, when compared to Saemangeum Lake, the environment is similar to that of Lake Shihwa, Cu, Ni, Hg, Mn, and Zn were 244.4 times higher. The levels of Pb, Cd, and Hg in fish's muscles did not exceed the average values set by the marine safety standard. However, when compared to the fish from the Korean coast, the levels of heavy metals were 9.7 times higher, on average. The levels of heavy metals in fish's livers were on average 26.8 times higher than in the muscles. In the case of shellfish, the levels of Pb, Cd, and Hg did not exceed the standard values, but in comparison to the shellfish from the south coast, the levels of heavy metals were 6.2 times higher on average. In particular, Mn (153.5 times higher) from fish and Cd (14.7 times higher) from shellfish were found in high amounts, indicating a concerning level of these specific heavy metals.

• Ocean and Polar Research
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• v.25 no.4
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• pp.447-457
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• 2003

In order to understand the distribution of changes of geochemical characteristics in surface sediments according to various environmental changes around the artificial Lake Shihwa, surface sediments were sampled at $13{\sim}15$ sites form 1997 to 1999 and analyzed by C/S analyzer, ICP/MS and AAS. The average $S/C_{org}$ ratio was 0.35 in the surface sediments, which is similar to 0.36, the characteristic ratio of marine sediments. Heavy metal contents and enrichment factors in the surface sediments tended to be decreasing from the head to the mouth of the Lake Shihwa. With the deposition of fine-grained sediments in the central part of lake, anoxic water column induced the sulfides compounds with Cu, Cd and Zn. Metals such as Al, Fe, Cr, Co, Ni, Cu, Zn and Cd except for Mn and Pb showed relatively high correlation coefficients among them. The contents of Cr, Co, Ni, Cu, Zn and Cd in the surface sediments of the lake were two to five times higher than those in the lake before dike construction and also in outer part of the dike. These are mainly due to the Input of untreated industrial and municipal waste-waters into the lake, and the accumulation of heavy metals by limitation of physical mixing. Although metal contents of the surface sediments at the sites near the water-gate due to outer seawater inflow tended to be lower than those during the desalination, heavy metals were deposited in areas around the new industrial complex in the evidence of spatial distribution of heavy metals in the sediments. This is mainly due to the input of untreated waste-waters from tributaries.

• Ocean Science Journal
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• v.42 no.4
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• pp.223-230
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• 2007

To understand the origin and biogeochemistry of the organic matter in surface sediments of Lake Shihwa and Lake Hwaong, organic nitrogen, inorganic nitrogen, labile organic carbon, and residual organic carbon contents as well as stable isotope ratios for carbon and nitrogen were determined by KOBr-KOH treatment. Ratios of organic carbon to organic nitrogen $(C_{org}/N_{org})$ (mean = 24) were much higher than ratios of organic carbon to total nitrogen $(C_{org}/N_{tot})$ (mean= 12), indicating the presence of significant amounts of inorganic nitrogen in the surface sediments of both lakes. Stable isotope ratios for organic nitrogen were, on average, $5.2\%_{\circ}$ heavier than ratios of inorganic nitrogen in Lake Shihwa, but those same ratios were comparable in Lake Hwaong. This might be due to differences in the origin or the degree of degradation of sedimentary organic matter between the two lakes. In addition, stable isotope ratios for labile organic carbon were, on average, $1.4\%_{\circ}$ heavier than those for residual organic carbon, reflecting the preferential oxidation of $^{13}C$-enriched organic matter. The present study demonstrates that KOBr-KOH treatment of sedimentary organic matter can provide valuable information for understanding the origin and degradation state of organic matter in marine and brackish sediments. This also suggests that the ratio of $(C_{org}/N_{org})$ and stable isotope ratios for organic nitrogen can be used as indexes of the degree of degradation of organic matter.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.3
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• pp.198-207
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• 1999

Five core sediments acquired from the Lake Shihwa are analyzed for variations of sedimentary environment and heavy metal pollution after the Shihwa seawall construction. The depositional environment of the study area is divided into anoxic, oxic and mixed suboxic conditions based on the C/N ratio and C/S ratios of organic matters. Controlling factors for redox condition are the water depth and the difference in industrial effluents supply. Correlations among geochemical elements (Mn, U, Mo) show a distinctive difference and thus can be used as an indicator of redox condition. The content of Al, Ti are dependent on the sediment characteristics, and the contents of heavy metals (Cr, Ni, Cu, Zn, and Pb) indicate heavy metal pollution. The concentrations of heavy metals are higher near Shiswa-Banwol industrial complexies than the central part of Lake Shihwa. Especially, the accumulation of the heavy metal at the surface sediments near Shihwa-Banwol industrial complex are two to eight times higher than in the center of Lake Shihwa.

• Atmosphere
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• v.21 no.4
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• pp.405-414
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• 2011

In this study, the influence of a change in land use on the local weather fields is investigated around the Lake Shihwa area using synthetic land cover data and a high-resolution mesoscale model - the Weather Research and Forecasting (WRF). The default land cover data generally used in the WRF is based on the land use category of the United States Geological Survey (USGS), which erroneously presents most land areas of the Korean Peninsula as savannas. To revise such a fault, a multi-temporal land cover data, provided by the Ministry of Environment of Korea, was employed to generate a land cover map of 2005 subject to the land use in Korea at that time. A new land cover map of 1989, before the construction of the Lake Shihwa, was made based on the 2005 map and the Landsat 4-5 TM satellite images of two years. Over the areas where the land use had been changed (e.g., from sea to wetlands, towns, etc.) due to the Lake Shihwa development project, the skin temperature decreased by up to $8^{\circ}C$ in the winter case while increased by as much as $14^{\circ}C$ in the summer case. Changes in the water vapor mixing ratio were mostly affected by advection and topography in both seasons, with considerable increase in the summer case due to continuous sea breeze. Local decrease in water vapor occurred over high land use change areas and/or over downstream of such areas where alteration in wind fields were induced by changes in skin temperature and surface roughness at the areas of land use changes. The albedo increased by about 0.1% in the regions where sea was converted into wetland. In the regions where urban areas were developed, such as Songdo New Town and Incheon International Airport, the albedo increased by up to 0.16%.

• 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.

• Environmental Analysis Health and Toxicology
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• v.23 no.4
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• pp.267-276
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• 2008

Acute and chronic toxicities of sediment elutriate and surface water samples collected at Lake Shihwa were evaluated using standard toxicity testing organisms including Vibrio fischeri, Daphnia magna and Moina macrocopa. Acute exposure resulted in toxic effects in all surface water or sediment elutriate samples, except for those collected from the reed swamp and Okgu stream. The rainy season influenced the toxicity of the water samples, presumably either by dilution of point discharge or through introduction of non-point source contaminants through runoff. In the sediment, elutriate and surface water samples, copper was detected above potentially lethal concentration, which may in part explain the observed toxicity. Considering acute toxicities of the surface water streams that direct to the Lake Shihwa, efforts should be warranted to control and reduce discharge of point and non-point sources along Lake Shihwa.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.49-52
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• 1997

The man-made lake, Shihwa, was constructed in January, 1994 as a part of the 'development project of the Shihwa area'. The lake area was a typical coastal ocean environment before the construction, but after constructing the dikes to block the sea water inflow, the lake is in the process of becoming a freshwater lake, and faces various ecological changes. Due to the polluted water inflow from the neighboring industrial complex and Ansan city, many negative effects appear. In this group study we conducted integrated ecosystem investigations of the lake Shihwa and the adjacent coastal area in order to find out how the ecosystem is controlled by artificial changes of the lake environment. The results are compiled in the following several articles of this issue: Park et ai. (1997), Han et al. (1997). Choi et ai. (1997), Park and Huh (1997), Ryu et at. (1997), Lee et al. (1997).

• Ocean and Polar Research
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• v.25 no.4
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• pp.459-468
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• 2003

Annual variation of water qualities in the Shihwa Lake were observed 18 times from June 1996 to October 2001. We studied at the station of the upper streams and near the water gate of lake. After the flow of the outer seawater through the water gate, the surface salinity in Shihwa Lake increased to the range of 25-30 psu in both stations after October 1998. Due to the declination of the salinity differences between the surface and the bottom water, the pycnocline in which had existed until 1997 has weakened, and made the water column mix vertically. This led to the improvement of anoxic/hypoxic environment at bottom waters after April 1998. However, despite the continuous flow of the outer seawater, the concentrations of chlorophyll-a at surface layer were varied from $2{\mu}g/l\;to\;60{\mu}g/l$, and these values indicated the eutrophication. The following organic matter load was greatly influencing the surface layer's COD concentration. During the rainy season, the salinity at the surface layer to the below 15 psu resulting in stratification between the surface and bottom layer. Organic matters that were provided from the surface layer to the bottom layer due to active primary production in the year exhausted dissolved oxygen at the bottom layer, and the bulks of organic matters at bottom gave rise to hypoxic or anoxic environment. It was observed that the enrichment of ammonia and phosphate were main factors to worsen the water quality of the Shihwa Lake. The results of examining the annual variations in Shiwha Lake through principal component analysis shown that water characteristics in the rainy season were similar with those before input of outer sea water.