• Journal of Marine Bioscience and Biotechnology
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• v.2 no.4
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• pp.201-208
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• 2007

Polychlorinated biphenyls (PCBs) are anthropogenic contaminants found globally in water, ice, soil, air and sediment. Modern analytical techniques allow us to determine these chemicals in environmental matrices at parts per trillion levels or lower. Environmental forensic on PCBs opens up new avenues of investigation such as transport and fate of water masses in oceans, sedimentation, onset of primary production, migration of marine mammals, their population distribution and pharmacokinetics of drugs inside organisms. By virtue of persistence, bioaccumulation, bioconcentration and structure-activity relationship PCBs emerge as unconventional chemical tracers of new sort.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.777-787
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• 2017

Organic enrichment and pollution was investigated in surface sediments from Jinhae Bay and Geoje-Hansan Bay of Korea, which contain the largest oyster farms in Korean coastal areas. Geochemical indicators (chemical oxygen demand, total organic carbon, ignition loss, and acid volatile sulfide) in sediments, ammonium and nitrate in pore water, and bioluminescence inhibition test for sediment extracts were analyzed. Temporal changes of organic enrichment were also investigated using sediment core samples from Geoje-Hansan Bay. The level of organic pollution in sediments from Jinhae Bay was significantly greater than that of sediments from Geoje-Hansan Bay. Compared with other sites, Jinhae Bay was one of the most polluted coastal areas of Korea. The levels of geochemical indicators in May were comparable to, or higher than, in August. Ammonium concentrations in pore water were two orders of magnitudes greater than the nitrate concentrations, suggesting that the bays are reducing environments. The concentrations of total organic carbon in core sediment samples from shellfish-farming areas increased significantly from 2000 to the present year, and it seems to be associated with increases in anthropogenic activities.

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.167-181
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• 2010

To predict changes in the marine environment of the Beolgyo Stream Estuary in Jeonnam Province, South Korea, where cohesive tidal flats cover a broad area and a large bridge is under construction, this study conducted numerical simulations involving tidal flow and cohesive sediment transport. A wetting and drying (WAD) technique for tidal flats from the Princeton Ocean Model (POM) was applied to a large-scale-grid hydrodynamic module capable of evaluating the flow resistance of structures. Derivation of the eddy viscosity coefficient for wakes created by structures was accomplished through the explicit use of shear velocity and Chezy's average velocity. Furthermore, various field observations, including of tide, tidal flow, suspended sediment concentrations, bottom sediments, and water depth, were performed to verify the model and obtain input data for it. In particular, geologic parameters related to the evaluation of settling velocity and critical shear stresses for erosion and deposition were observed, and numerical tests for the representation of suspended sediment concentrations were performed to determine proper values for the empirical coefficients in the sediment transport module. According to the simulation results, the velocity variation was particularly prominent around the piers in the tidal channel. Erosion occurred mainly along the tidal channels near the piers, where bridge structures reduced the flow cross section, creating strong flow. In contrast, in the rear area of the structure, where the flow was relatively weak due to the formation of eddies, deposition and moderated erosion were predicted. In estuaries and coastal waters, changes in the flow environment caused by artificial structures can produce changes in the sedimentary environment, which in turn can affect the local marine ecosystem. The numerical model proposed in this study will enable systematic prediction of changes to flow and sedimentary environments caused by the construction of artificial structures.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.392-402
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• 2020

We investigated the concentrations of acid volatile sulfide (AVS), ignition loss (IL), total organic carbon (TOC), total nitrogen (TN), and metallic elements (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn), in August 2015, to determine the spatial distribution and pollution status of organic matter and metals in the surface sediment of Jinju Bay, a spraying shellfish farming area, Korea. The concentrations of organic matter and metallic elements were significantly higher in the southern part of the bay than in the mouth and center of the bay. The C/N ratio (5.7~8.0) in the sediment represents the dominance of organic matter of oceanic origin in the surface sediment of the study area. The concentrations of AVS, TOC, and metals (As, Cd, Cr, Cu, Hg, Pb, and Zn) were much lower than the values of the sediment quality guidelines applied in Korea. Based on the results of the pollution load index (PLI) and ecological risk index (ERI), the metal concentrations in the surface sediment of Jinju Bay have a weakly negative ecological effect on benthic organisms although the sediments with high metal pollution status are distributed in the southern parts of the bay, with high dense shellfish farming areas. Thus, the surface sediments in Jinju Bay are not polluted with organic matter and are slightly polluted with metallic elements.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.216-216
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• 2017

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.218-218
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• 2017

• Ocean and Polar Research
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• v.32 no.4
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• pp.337-350
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• 2010

This study conducted sedimentological and geophysical surveys for 3 years (2006-2008) in southern Gyeonggi Bay, Korea to elucidate temporal changes in subaqueous dune morphology on a sand ridge trending northeast to southwest that has been excavated by marine sand mining. The sand ridge (~20 m in height, ~2 km in width and 3~4 km in length) has a steep slope on the NW side and a gentle slope on the SE side, creating an asymmetric profile. Large (10~100 m in length) and very large (>100 m in length) dunes occurring on the SE side of the ridge show a northeastward asymmetrical shape, whereas dunes on the NW side destroyed by marine sand mining display a southwestward asymmetry. The comparison between Flemming (1988)'s correlation and the height-length correlation of this study indicates that tidal current and availability of sand sediment are major controlling factors to the development and maintenance of dunes. Depth and sedimentary characteristics (grain size) are not likely to be major controlling factors, but indirectly influence dune growth by hydrological and sedimentary processes. The length and the height of dunes decrease toward the southeastern trough away from the crest of the ridge. These features result from the decrease of tidal current and sediment availability. The length and the height of dunes on the southeast side decrease gradually over time. This is a result of the interaction between tidal current and the decrease in sediment availability due to sediment extraction by marine sand mining. Marine sand mining has destroyed the dunes directly, causing irregular shapes of shorter length and lower height. The coarse fraction of suspended sediments is transported and deposited very close to the sand pit. By contrast, relatively fine sediments are transported by the tidal current and deposited over a wide range by the settling-lag effect, resulting in a decrease of sediment grain size in the area where suspended sediments are deposited. In addition, marine sand mining, decreases the height of dunes. Therefore, morphological and sedimentological characteristics of dunes around the sand pits will be significantly changed by future sand mining activities.

• Fisheries and Aquatic Sciences
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• v.15 no.3
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• pp.241-250
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• 2012

Polycyclic aromatic hydrocarbons (PAHs), butyltins (BTs), nonylphenol (NP), and fecal sterols concentrations in sediments were investigated from Gunsan coast of Korea to evaluate organic pollution from anthropogenic activities. Sediment toxicity was also examined by bacterial bioluminescence toxicity test (Vibrio fischeri). The concentrations of 16 PAHs in sediments ranged from 67.9 to 425 ng/g dry wt; BTs ranged from 2.79 to 14.1 ng Sn/g dry wt; NP ranged from 20.7 to 2171 ng/g dry wt; and coprostanol, a fecal sterol, ranged from 7.60 to 245 ng/g dry wt. Effective concentration 50% ($EC_{50}$) of sediments ranged from 0.38 to 23.8 mg/mL. Most of the chemicals were present at levels lower than or comparable to the previously reported values from Korea. However, NP levels in the present study were in the high range of levels reported from the Korean coast, and 40% of the measured samples exceeded screening and ecotoxicological values of NP suggested by the Netherlands and Canada. This suggests that an ongoing source of NP is a serious concern in the Gunsan coast. High levels of contaminants were found in the proximity of potential sources, such as the outfall of a wastewater treatment plant for NP, an anthracite-fired power plant for PAHs, and ports for BTs, fecal sterols, and sediment toxicity. This indicates that Gunsan coast has various potential sources of marine sediment contaminants.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.366-372
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• 2020

Using several accessible published data sets, we analyzed the temporal change of ¹³⁷Cs radioactivity (per unit mass of sample) in marine sediments and investigated the effect of the water content of sediment on the ¹³⁷Cs radioactivity, to understand the behavior of ¹³⁷Cs present in marine environments. The ¹³⁷Cs radioactivity in sediments decreased more slowly in the Baltic Sea (near the Chernobyl nuclear power plant) than in the ocean near the Fukushima Daiichi nuclear power plant (FDNPP). The ¹³⁷Cs radioactivity in the sediment near the FDNPP tended to increase as the water content increased, and the water content decreased at certain sampling sites near the FDNPP for several years. Additionally, the decrease in the water content contributed to 51.2% of the average ¹³⁷Cs radioactivity decrease rate for the same period. Thus, it may be necessary to monitor both the ¹³⁷Cs radioactivity and the water content for marine sediments to track the ¹³⁷Cs that was discharged from the sites of Chernobyl and Fukushima nuclear power plants where severe accidents occurred.

• Ocean and Polar Research
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• v.24 no.2
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• pp.167-175
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• 2002

Sediment from six piston cores from the East Sea (Sea of Japan) was analyzed for evidence of paleoceanographic changes and paleoclimatic variation. A distinct geochemical boundary is evident in major element concentrations and organic carbon content of most cores near the 10-ka horizon. This distinctive basal Holocene change is interpreted to be largely the result of changing sediment sources, an interpretation supported by TiO_2/Al_2O_3$ ratios. Organic carbon and carbonate contents also differ significantly between the Holocene and glacial intervals. The C/N ratio of organic matter is greater than 10 during the glacial period, but is less than 10 for the Holocene, suggesting that the influx of terrigenous organic matter was more volumetrically important than marine organic matter during glacial times. The chemical index of weathering (CIW) is higher for the Holocene than the glacial interval, and changes markedly at the basal Holocene geochemical boundary. Silt fractions are higher in the glacial interval, suggesting a strong effect of climate on silt particle transportation: terrigenous aluminosilicates and continental organic carbon transport were higher during glacial times than during the Holocene. Differences in sediment composition between the Holocene and glacial period are interpreted to have been climatically induced.