• Journal of Wetlands Research
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• v.14 no.3
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• pp.375-384
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• 2012

The sedimentary processes of the Ganghwa tidal flat has been changed over 20 years because of the large-scale construction projects. The sedimentary environment of the Donggum tidal flat, located in the eastern part of Ganghwa tidal flat and in the lower reaches of Yeomha channel, was affected by changes the tidal current regime and estuarine circulation. These resulted an occurrence of rapid deposition in the tidal flat. The silt-clay laminated silt facies in the upper parts of two core sediments suggested that deposition had been relatively high in the tidal flat. The sedimentation rates from the cores using $^{210}Pb$ analysis were 3.25cm/year(st. 3) and 3.47cm/year(st. 5). However the short-term sediment accumulation rates from 2010 to 2012 were mostly less than 1cm/year, indicated that the sediments deposited relatively low rates. As a result, the sediment in the Donggum tidal flat rapidly accumulated during 2000s due to constructions of man-made structures. Recently, the increase of elevation in the tidal flat resulted to show relatively low sedimentation rate with seasonal variations.

• Economic and Environmental Geology
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• v.36 no.1
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• pp.9-15
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• 2003

Two piston cores, obtained from the southwestern Ulleung Basin in East Sea, were analyzed to study the geochemical characteristics of the late Quaternary sediments and to detect any changes in sedimentary environment. The results show that the capacity of Total Organic Carbon is remarkably higher (average 1.8%) than that known from general open-sea. According to tephrochronology from known eruption ages, the sedimentation rates are high, ranging from 12.1 to 14.9 cm/kyr. The ratios of nitrogen and TOC (average 6.18-7.42) imply that the organic matter in the study area would be of oceanic origin. The correlation between sedimentation rates and sulfur contents suggests that the study area may be on the whole anoxic and somewhat high in primary productivity. During the Termination 1, inflows of organic matters were high. The sedimentary environments are characterized by rapid rates of sedimentation, and high anoxic values were compatible with accumulation of organic matters.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.2
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• pp.70-80
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• 2014

We carried out numerical experiments to understand sedimentary environments in Gamak Bay where is located in the center of the southern coast of Korea. Deposition rates in Gamak Bay appeared to increase in the autumn and spring whereas they appeared to decrease in the summer and winter. These seasonal variations qualitatively coincided with seasonal variations of Ignition Loss (IL) for surface sediments. Furthermore, deposition rates turned out to be prevalent compared to erosion rates in most areas of the bay. On the other hand, current measurement results at both the northeast and south mouths of the bay showed their residual components to flow into the bay. Therefore, we can conclude that contaminated materials flowing into Gamak Bay will precipitate to be deposited in the bay as long as there is no specific events such as dredging.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.656-665
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• 2019

Environmental monitoring was conducted to identify the characteristics and patterns of sedimentary environments of tidal flats in 12 areas on the west coast of Korea. The habitat of the mud shrimp Upogebia major contained higher organic and mud contents compared to the habitat of the manila clam Ruditapes philippinarum. In particular, the mud content increased from 84.38% to 89.18% in the Seongam-4 area, where the mud shrimp and manila clam coexist, and the mean grain size exhibited a finer particle size, from 5.48 Φ to 5.80 Φ. In the mud shrimp habitat, the sediment mud content was > 60% and the mean grain size was > 5 Φ. Additionally, the mud shrimp only inhabited open coast tidal flat areas. The management of shellfish aquaculture farms by physical methods should be continued based on comparison of the sedimentary environments in the Boryeong and Seongam areas in response to the damage to the mud shrimp habitat.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.67-78
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• 2010

Surface sedimentary facies and the change of microphytobenthos distribution in Geunso Bay tidal flat were monitored using remotely sensed data. Sediment distribution was analyzed along with the spectral reflectance based on the in situ data, and the spectral characteristics of the area where microphytobenthos occupied was examined. A medium to low spatial resolution of satellite image was not suitable for the detection of the surface sediments changes in the study area due to its ambiguity in the sedimentary facies boundary, but the seasonal changes of microphytobenthos distribution could be obviously detected. However, area of predominance of sand grains and seagrass distribution could be distinctly identified from a high spatial resolution remote sensing image. From this, it is expected that KOMPSAT-2 satellite images can be applied effectively to the study on the surface sedimentary facies and detailed ecological mapping in a tidal flat.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.185-190
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• 2008

Geophysical survey were investigated in the offshore around East Sea Research Institute, Korea Ocean Research and Development Institute (Jukbyeon-myun, Uljin-gu, Gyeongsangbuk-do, Korea). The surveys were conducted aboard the R/V Jangmok in 2008 using a hull-mounted EM 3002 multi-beam echosounder. Precise bathymetry and seabed images were obtained using multi-beam and thicknesses of sedimentary layer were found through seismic survey. Submarine topography deepens parallel to the coastline to -60 m and rock mass distributed in the southeast of study area. By finding the thickness of sedimentary layer through seismic survey, a sedimentary thickness on the study area was established. Futhermore, monitoring data of bathymetry, substructure and sedimentary environment will be secured through successive geophysical investigation.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.208.1-208
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• 1998

No Abstract, See Full Text

• The Korean Journal of Quaternary Research
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• v.22 no.2
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• pp.42-42
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• 2008

• Journal of Environmental Science International
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• v.20 no.7
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• pp.829-837
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• 2011

A study on the grain size change, sedimentary facies and age indicator of volcanic tephra was analysis through four cores (P1 ~ P4) at the Ulleung Basin in the East Sea of Korea. The two cores (P1 and P2) were collected in the northeastern side of the Ulleung Basin (about 2,000 m in water depth), while the other two cores (P3 and P4) with the water depth of about 1,500 m and 1,700 m, respectively, were collected from the continental slope of the southwestern and western side of the Ulleung Basin. Four sedimentary facies and eight sedimentary subfacies were identified. The four facies were massive sand, bioturbated mud, homogeneous mud, and laminated mud. The eight subfacies were further divided as pumiceous ash massive sand, scorieaous massive sand, plain bioturbated mud, pyrite filamented bioturbated mud, distinctly laminated mud, indistinctly laminated mud, thinly laminated mud and homogeneous mud. The homogeneous mud was not found in the core of P3 which is located in the western side of Ulleung Basin (close to the Korean coast). In the case of laminated mud facies, the thinly laminated mud facies was dominated in the lower part of core sequences of the Ulleung Basin (P1 and P2), while the indistinctly laminated mud were overally distributed in the core sequences from the continental slope of Ulleung Basin. The Tephra layers from the core sequences of central Ulleung Basin were more dominated and distinctive than those from the core sequences of continental slope. This is related to the distance from the volcanic source and the amount of sediment supply. The core locations of Ulleung-Oki Tephra layers in the central Ulleung Basin were in the upper part of core sequences, while those in the continental slope were in the lower part of core sequences. This is indicated that the amounts of sediment supply in the continental slope after the Ulleung-Oki eruption were very high and different sedimentary environment between upper and lower of Tephra layer.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.191-202
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• 2010

In this study, the relationship between the settlements and the horizontal displacements according to embankment was analyzed at the marine sedimentary grounds for preparation of a site, and then the empirical equations of both the settlement and the horizontal displacement considering the embankment load and the thickness were proposed. To do this, the field and laboratory tests were performed at the improvement section where the pre-loading method was applied, and the field monitoring was performed using various sensors. Based on the results of the tests and monitoring, the ground deposits, soil characteristics and engineering properties were analyzed and the settlements and lateral movements were estimated by the Regression analysis. The ground deposits from the ground surface were composed of reclaimed soils, sedimentary soils and based rocks. The thickness of clay in the sedimentary soils layer was ranged from 3.9 m to 44.5 m. The embankment heights to improve the ground during pre-loading were constructed from 4.7 m to 7.8 m in each section. The settlements during embankment were ranged from 0.959 m to 2.217 m and the lateral movements were ranged from 0.048 m to 0.313 m. As the result of regression analysis, the equations of settlements and horizontal displacements according to embankments may be proposed as $s=0.02h^2+0.11h$ and ${\delta}=0.01e^{0.37h}$, respectively. The proposed empirical equations of the settlements and the horizontal displacements according to embankment on the marine sedimentary ground may be applied to the site where has a similar condition of study area.