• Ocean Science Journal
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• v.41 no.3
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• pp.139-148
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• 2006

The distribution of the taxonomical composition and the density of meiobenthos depending on the sediment type has been studied in bottom sediments of Nha Trang Bay. The maximal population density and the taxonomical diversity were observed in the silted coarse and heterogeneous sand ($1031.4{\pm}419.7\;ind.\;10\;cm^{-2}$), whereas the minimal level of density and diversity ($588.1{\pm}152.5\;ind.\;10cm^{-2}$) was in the coarse and heterogeneous sand with shell debris and corals. The correlation between the median diameter of sediment particles and population density of meiobenthos has been revealed (r=0.82, p<0.05). In bottom sediments of Nha Trang Bay, twenty six taxonomic groups of meiobenthos were observed. Nematodes dominated in all sediment types. Representatives of four orders, twenty eight families and ninety seven genera of marine nematodes were identified. The vertical distribution of meiobenthos in different sediment types was considered. A sediment column (10 cm height) was sectioned by five 2 cm portions. In the last layer (8-10 cm) the most number of meiobenthic groups was found in sandy sediments. In the lower layers of silt sediments, only nematodes were found.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.355-358
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• 2002

A sediments are Integral called as gravel, sand, clay, mineral materials which are settling in bottom layer of reservoir, stream, and oceans from land. In practical problems relations of sediments are flood by decreed of flow capacity and down of water quality. Dredged sediments are composed with constructed material and variety of pollutant compounds. Therefore, it is very much of cost effects in nationally, if development for use of constructed material separated only constructed material within sediments. And it will be continue to the dredge operation of stream sediment for retrofit of water environment and sustainable's after the years. The following results could be obtained : In case of high concentration sediments, sample for design of CDF was shown property of flocculent settling. Assuming that average inflow rate is 1, 000㎥/hr, mean residence time( $T_{d}$), average ponding depth( $H_{pd}$ ), and design surface area for flocculent settling( $A_{df}$ ) were 5 hr, 0.6m, and 15, 750 $m^2$ respectivelyrespectivelyy

• The Journal of the Acoustical Society of Korea
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• v.23 no.5
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• pp.362-369
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• 2004

The High-frequency (30 ∼ 120 ㎑) bottom reflection loss at rough water-sediment interface is affected by the gram size distribution of the sediments. The roughness of the bottom surface is represented by "acoustical roughness. g/sub R/" The grain size of sandy sediments is g/sub R/∼O(1) and the dependence as a function of frequency. We suggest the modified bottom reflection loss model (HYBRL model , HanYang university Bottom Reflection Loss model) that include in the deviation of the reflection loss as a function of the grain size distribution and frequency dependence. And bottom reflection loss model of frequency dependence and deviation of bottom properties is verified by water tank and field experiments.

• 한국해양학회지
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• v.28 no.4
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• pp.313-322
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• 1993

The Western south Sea of Korea can be divided into 4 acoustic facies (AF I-AF IV) according to the variations of acoustic characters. Typical acoustic characters revealed in high-resolution seismic profiles (3.5kHz) are prolonged, internal reflected, non-penetrated, and transparent types. These acoustic types probably controlled by bottom condition and sediment properties such as composition and compaction of sediments. Acoustic facies I is characterized by prolonged type which is produced by absorbing of acoustic signals on the coarse sediments including gravels and shell fragments and irregular bedforms. Acoustic facies II is characterized by internal reflected type which is probably produced by differential sediments compaction. Acoustic facies III is characterized by non-penetrated type caused by scattering of acoustic signals on the well sorted fine ad very fine sand sediments. Acoustic facies IV is characterized by transparent type with non-internal reflector in limited thickness. Acoustic types in high-resolution profiles provide important information not only about the stratigraphy of sub bottom but also abut the sedimentary processes in shallow sea.

• 한국해양학회지
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• v.1
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• pp.16-24
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• 1971

Over 40 bottom sediment samples were collected from the southern sea of Korea. The detailed textural characteristic of the sediments, percent calcium carbonate and heavy and light mineralogy were determined. Seaward of these sediments is a nearly broad belt of sandy sediments. In a broad outline it is considered to constitute a near-shore deposits left from a Pleistocene time of eustatically lowered level of sea water, because the sediments on the outer half of the continental shelf are much coarser than that nearer shore. The carbonate content increases strongly to the southeast and northwest of Cheju Island. It is believed that the high calcium carbonate content can be largely attributed to the availability of carbonate materials.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.128-137
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• 1997

This study presents results from a detailed sedimentological investigation of surface sediments obtained from the Korea Strait region, the southern part of the East Sea (Sea of Japan). The distribution of different types of bottom sediments is controlled by the recent fine-grained sediment transport and deposition combined with the lowerings of sea level during the last glacial period, forming a diverse mixture of organic-rich fine-grained and shelly coarse-grained sediments. In comparison to high organic concentration of fine-grained sediments in the inner continental shelf and slope areas, the shell-rich coarse-grained sediments on the outer shelf are discernible being further modified. These coarse-grained sediments are confirmed as relict resulting from the sediment dynamics during the lower sea levels of the last glacial period. Clay mineral distribution of the fine-grained sediments gives information about the transport mechanism. Presence of present-day current system (the Tsushima Warm Current) is most probable source for the fine-grained particles into the open East Sea from the East China Sea, indicating that Holocene sediment dynamics may be used to explain the observed distribution of surface coarse-grained shell-rich sediments.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.103-111
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• 1997

Biogeochemical cycling of organic carbon is quantitatively partitioned in terms of 1) flux to the ocean bottom, 2) benthic utilization at or near the sediment-water interface, 3) remineralization and 4) burial within sediments, by making an independent determination for each component process from a single coastal site in Kwangyang Bay. The partitioning suggests that the benthic utilization at or near the sediment-water interface is the major mode of organic carbon cycling at the site. The benthic utilization takes 61.8% (441.6 gCm$^{-2}$ yr $^{-1}$) of the total near-bottem organic carbon flux, 714.6 gCm $^{-2}$yr$^{-1}$, and far exceeds the remineralization of organic carbon within the sediments which amounts only to 6% (41.24 gCm$^{-2}$yr$^{-1}$) of the total near-bottom flux. The residence time is about 1.6 years for the sedimentary metabolic organic carbon in the upper 45 cm. The dominant partitioning of the benthic utilization in the carbon budget suggests that most of labile organic carbons are consumed at or near the sediment-water interface and are left over to the sediment column by significantly diminished amounts.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.3
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• pp.1-9
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• 1999

This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.

• Journal of the Korean earth science society
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• v.25 no.1
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• pp.1-9
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• 2004

The clay minerals of thirty-four bottom sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more-than 70% of whole clay fraction. The highest concentration of illite (>72%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Cheju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea. Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where the fine-grained sediments are discharged from the modern and ancient Huanghe River. The relatively high abundance of kaolinite is likely derived from the Changjiang River via Taiwan ·Warm Current. In contrast, the large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern are, reflecting the transportation by the Huanghai Sea Coastal Current from the southern Yellow Sea.

• Journal of Environmental Science International
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• v.11 no.12
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• pp.1299-1305
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• 2002

Thirty sediment samples of the <63${\mu}{\textrm}{m}$ fraction collected from the southwestern coast of Korea were analysed for their heavy metal (Fe, Mn, Cr, Co, Cu, Ni, Zn and Pb) concentration. The results show that sediment texture plays a controlling role on the total metal concentrations and their spatial distribution. A single lM HCl extraction procedure was used in order to assess the environmental risk of heavy metals in bottom sediments. The non-residual fraction was the most abundant pool for Mn and Pb in most samples, which means that this metals are highly avaliable in these sediments. Cr, Ni, Fe, Co, Zn and Cu were mainly associated with the residual fraction, suggesting that their concentrations are controlled significantly by transport processes with the fine particles as carriers from diffuse pollution source. Concentration enrichment ratios(CER) were calculated from the non-residual contents and their values allowed us to classify the sediments according to their environmental risk.