• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.345-354
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• 2009

The review of statements and coastal development characteristics in South Korea were diagnosed by the consultation on the coastal area utilization in Korea. The occupation and the use of public water were dominated by installation of coastal structure and seawater supply and drainage whereas the reclamation areas were predominantly utilized for developing industrial complex, harbor, fishing port and road. The occupation and the use were dominant in western coast, but reclamation was dominant in southern coast of Korea. The number of utilization cases was particularly greater in Jeonnam, Gyeongnam, and Gyeonggi Province including Incheon. The number of the statements reviews increased by more than 200 cases in 2008 compared with 2007, and most of them were the simple statements. The statements related to ocean disposal of dredged sediment, reclamation, dredging sediment, seawater supply and drainage, and marine sand mining were submitted for review. Coastal utilization was especially active in the regions of seawater quality criteria I and II. In particular, special management sea areas designated under the relevant marine regulations were utilized mostly by reclamation for developing harbor, fishing port and coastal structure. Development activities in national parks comprised primarily structure installation and coastal maintenance. In the fisheries resources protection areas, 40% of the total cases accounted for coastal maintenance, 31% for structure installation, and 16% for seawater supply and drainage. In addition, alternative plans for the improvement in policies and system of marine environmental impact assessment were suggested to enhance the function and confidence of the consultation on the coastal area utilization in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.423-432
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• 2004

In coastal area of Inchon, dredging and the disposal of dredged material for sea-wall construction and reclamation have increased in recent years. These activities may impact the benthic environment and result in changes in benthic communities, but little information is available on the extent and direction of these changes. We investigated whether there have been changes in the dominant macrobenthic species and benthic community over the last decade, and explored the relationship between environmental variables and spatial patterns of macrobenthic community structure. We sampled macrobenthos and recorded environmental variables in the coastal habitats of Inchon in March and June 2004. In total, 212 macrobenthic species were recorded during this study, predominately crustaceans $(34{\%})$, mollusks $(32{\%})$ and polychaetes $(21{\%})$. The mean density of macrobenthos was $1,393\;ind./m^{2}$.The most abundant species was Amphioplus japonicus $(20.5{\%})$, followed by Heteromastus filiformis $(14.4{\%})$, Theora fragilis $(8.2{\%})$ and Ampharete sp. $(4.0{\%})$. Over the past decade the dominant macrobenthic species in this area shifted. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure among three regions: the middle part of the sampling area (B), site 8 (C) and other sites (A). Mean density varied significantly among the three regions, but no differences in the number of species and diversity (H') were observed. The distribution of the macrobenthic community was affected by environmental variables such as percentage sand content and sediment kurtosis. Species that were important in different areas included A. japonicus in region A, Raeta puchella in region B and T. fragilis in region C. The important species in regions B and C were filter-feeding bivalves, and the abundance of these species may be related to the increase in percentage sand content. We suggest that the sediment composition (percentage sand content) may be an important factor in determining the dominant species and structure of the macrobenthic communities in coastal Inchon. Long-term monitoring programs are necessary to understand ongoing changes in the benthic communities of this area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.3
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• pp.93-105
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• 2004

Spatio-temporal distribution patterns of the major dominant species were assessed from bimonthly monitoring of macrotidal flat in Cheokjeon, Incheon, Korea between September 1990 and July 1992. Overall, macrofauna comprised a total of 111 species, 25,491 inds.136 ㎡. The result of Le Bris index, dominance ranking of the lead-ing species showed that the top 15 species accounting for 74.8% (19,072 inds.) of total density. In Cheokjeon tidal flat, some species were especially habitat-restricted such as genus Nephtys (Annelids; Polychaetes) and Mac-rophthalmus (Crustaceans; Decapods). Based on the density data, the five dominant species were the polychaetes Het-eromastus filiformis, the bivalves Mactra veneriformis and Solen strictus, the brachyurans Macrophthalmus japonicus, the holothuriodeans Protankyra bidentata. The results of one-way ANOVA, mean value of H. filiformis and M. ven-eriformis did not show significant changes with tidal elevation and sediment composition (p>0.05). But, other species (S. strictus, M. japonicus and P. bidentata) showed significant variations (p<0.001). In conclusion, these indicate significant spatial fluctuation with tidal elevation and sediment characteristics in some species.

• The Journal of the Acoustical Society of Korea
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• v.22 no.8
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• pp.652-659
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• 2003

High-frequency(40∼120 kHz) reflection loss measurements on the water-sandy sediment with a flat interface were conducted in a water tank for various grazing angles. The water tank(5×5×5 m) was filled with a 0.5 m-thick-flat bottom of 0.5ø-mean-grain-size sand. Reflection losses, which were experimentally obtained as a function of grazing angle and frequency, were compared with the forward loss model, APL-UW model (Mourad & Jackson, 1989). For frequencies below 60 kHz, the observed losses well agree with the reflection loss model, however, in cases for frequencies above 70 kHz, the observed losses are greater by 2∼3 dB than the model results. The model calculation, which does not fully account for the vertical scale of roughness due to grain size, produce less bottom losses compared to the observations that correspond to large roughness based on the Rayleigh parameter in the wave scattering theory. In conclusion, for the same grain-size-sediment, as frequencies increase, the grainsize becomes the scale of roughness that could be very large for the frequencies above 70 kHz. Therefore, although the sea bottom was flat, we have to consider the frequency dependence of an effect of roughness within confidential interval of grain size distribution in reflection loss model.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.1
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• pp.9-16
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• 2005

A series of experiments was conducted to evaluate the effects of temperature on the survival, growth and sensitivity of the benthic amphipods, Mandibuluphoxus mai and Monocnrophium acherusicum, which have been recently developed as new sediment toxicity testing species in Korea. The biological performance for each amphipod species was determined by the survival and growth rates at different water temperatures. The influence of temperature on the sensitivity to reference toxicant, Cd, was determined by the comparison of survival rates of amphipods exposed to control and Cd-spiked seawater at different temperatures. Temperature significantly influenced on the survival, growth and Cd sensitivity of both amphipods. Tolerable ranges of temperature for the >80％ individuals of both M. mai and M. acherusicum with sediment substrates were mostly overlapped (13 to 22℃). The daily growth rates of M. mai and M. acherkisicum increased proportionally with temperature up to 20℃ and 25℃. respectively. Similarly, the sensitivities of M. mai and M. acheyusicum to Cd increased with temperature up to 20℃ and 15℃, respectively. Overall results showed that temperature is a substantially important factor potentially influencing the results of lethal and sublethal bioassays using the amphipods. Therefore, defining the adequate ranges of experimental temperature for the toxicity testing species is the pre-requisite for the development of standardized bioassay protocols.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.851-857
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• 2014

Treatability of heavy metals in marine sediments contaminated with mainly organic matter was investigated on the basis of washing technology using oxidizers and surfactants. Sediment samples were collected at N area which expected for remediation project of contaminated marine sediment. For additives, hydrogen peroxide ($H_2O_2$) and Tween-80 were used at oxidizer and nonionic surfactant, respectively. In experiments, sediments was mixed with sea water at the ratio of 1 : 3 than $H_2O_2$ (1 M, 3 M, 4 M, 5 M) and Tween-80 (0.05%) were added. Samples were gathered at following reaction time (10, 20, 30, 40, 50, 60, 70, 80 min and 24 h). Total Organic Carbon (TOC) was 55.2% at the conditions of 5 M $H_2O_2+0.05%$ Tween-80 24 h. Hence total heavy metals were Cu 29.5%, Zn 42.3%, Cd 73.0% and bioavailable heavy metals were Cu 60.0%, Zn 77.7%, Cd 90.2% at the conditions of 5 M $H_2O_2+0.05%$ Tween-80 10 min. The correlations for between bioavailable metals (Cu, Zn, Cd) and TOC were significant (Cu, Zn, Cd; $r^2=0.94$, 0.85, 0.69, respectively).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.577-588
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• 1995

The chemical constituents for the seawater and sediment were measured to evaluate pollution in the sea around Pusan Harbor in winter, n992. The average value of trophic state index (TSI) was 19.4 at the outside of Buk Harbor, 50,4 at the inside of Buk Harbor, 56,3 at the Nam Harbor and 5,0 at the Kamchun Harbor. The high correlation found in salinity-nutrients diagram with AOU suggested that the enrichment of nutrients in Pusan Harbor during winter was mainly due to the influx of terrestrial effluents and partially by regenerated nutrients from suspended organic matters in the water column. The mean values of total ignition loss (TIL), COD and total sulfide in the surface sediments were$12.1\%$, 17.5 mg/g.dry wt. and 1.18 mg/g.dry wt. respectively. The highest level of those parameters was shown mostly at the inside of Buk Harbor. The mean concentration of total organic carbon (TOC), total organic nitrogen (TON), and total phosphorus were 24.9 mg/g.dry wt., 1.3mg/g.dry wt. and 0.69 mg/g. dry wt., respectively, Both of the highest level for TOC and total phosphorus have found at the Nam Harbor. On the other hand, the Highest level for TON was found at the inside of Buk Harbor. The TOC/TON atomic ratio with a range of 10.2-60.2 (mean value of 22.5) strongly indicated the active role of the input from the terrestrial organic pollutants.

• Journal of the Mineralogical Society of Korea
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• v.27 no.3
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• pp.159-168
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• 2014

Holocene plaeoenvironmental changes were interpreted by grain size and mineral analyses of a piston core (HB 13-2), obtained along the western slope of the Hupo Basin, Korea. The core sediments are characterized by two discrete, sedimentary facies: upper unit (0-0.4 mbsf) dominated by bioturbation structures with weak lamination, and lower unit (0.4-3.3 mbsf) characterized by intensified bioturbation toward bottom. Analysis of sensitive grain size and sortable silt demonstrated that the inflow of the Tsushima Warm Current (TWC) into the Hupo Basin strengthen from the period of sediment deposition over 0.82 mbsf. The minerals of the core sediments are composed mainly of quartz, microcline, orthoclase, albite and clay minerals including chlorite, kaolinite and illite. No noticeable changes of the mineral percentage was observed according to the grain size and depth of the samples. The integral breadth (${\Delta}^{\circ}2{\theta}$) of clay minerals from 1.4 mbsf to top layer shows an increasing trend, which clearly means climate warming from the period of sediment deposition above 1.4 mbsf. This interval correlates with the Holocene climate optimum at Mid Holocene.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.56-68
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• 2005

We measured nitrate and other nutrients in sediment pore waters retrieved from three sites at the southern upper-tidal flats of the Ganghwa Island. Denitrification rate is estimated by applying a simple 1-D model to the nitrate profiles. Results from Jangwha and Dongmak sites are $7.8{\sim}9.4{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, and $1.4{\sim}3.6{\times}10^{-7}{\mu}mol{\cdot}cm^{-2}{\cdot}sec^{-1}$, respectively. Rates are comparable to those reported around the world in an order of magnitude. Denitrification was lower in summer. The rates were about 1.5 times higher at site where the surface sediments consist of relatively coarser particles. This implies that particle size would control the reactant supply to the subsurface sediment. One may claim the denitrification as an evidence of the biogeochemical purification function of tidal flat. However, the purification seems not a general attribute of a tidal flat when whole system is scrutinized by a thermodynamic criterion. Currently the term 'tidal flat' is used when describing the diverse coastal wetlands such as salt marshes, sandy tidal flats and muddy tidal flats, which exhibit quite different ecological functions. Thus it is worthy of mentioning that the classification of coastal wetlands on the basis of sedimentological characteristics and biogeochemical functions should facilitate our understanding.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.69-77
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• 1997

A 12-cm long sediment core was collected from a station in Lake Shihwa where high salinity-anoxic deep water is isolated from low salinity-oxic surface water by a strong halocline barrier. Unprecedented concentrations of porewater ammonia and lead are encountered: at 9 cm sediment depth ammonia builds up to 1420 ${\mu}M$ and at 3 cm lead to 1348 nM. As they are stable in anoxic condition, high concentrations of ammonia and lead suggest a development of notorious anoxic condition in the benthic environment of the lake. The degree of pollution of the deep water is likely to be directly proportional to the magnitude of benthic flux, because the deep water is isolated from the surface water by the halocline. Apparent coincidence of the ammonia residence time in the deep water with the elapsing time after the completion of the artificial lake construction, as about three years, suggests that the deep water pollution is being progressed entirely by benthic flux at least with respect to ammonia. The residence time for lead is such a short 20 days that it suggests a rapid return of the bottom water lead, which is originated from porewater by benthic flux, back to sediments probably as metal sulfide phases. The speculation on the return of lead as sulfide phases is likely to be supported by high concentration of hydrogen sulfide in the deep water and by high sinking rate of non-organic particles in Lake Shihwa.