• Journal of the korean society of oceanography
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• 제38권1호
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• pp.17-23
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• 2003

We report the distribution of $^{210}$ Pb and various metallic elements (Al, Fe, Mg, Ca, Ti, Mn, Sr, Ba, Zn, V, Cr, Zr, Ni, Cu, and Y) in the sediment cores from six shellfish-farming bays in the South Sea of Korea. The $^{210Pb}$ inventories in Deukryang, Gwangyang, and Goseong Bay cores were comparable to those expected from the known fallout input. However, the $^{210}$ Pb inventories were two times higher in Jinju, Gangjin, and Hansan-Koeje Bay cores, suggesting an important role of other sources such as fluvial inputs. Based on the enrichment factor analyses, non-detrital fractions of all the measured elements were found to be insignificant. The Mn was highly enriched only in the surface sediments of the Jinju and Goseong Bay, which implies that the surface-sediment environment of these bays is efficiently oxidizing Mn remobilized from either pore waters or bottom seawaters. These data set provides the sources of heavy metal in sediment around shellfish farms and the current level of metallic elements for the future monitoring.

• Ocean and Polar Research
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• 제26권4호
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• pp.635-646
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• 2004

Chronic outbreaks of green tide in the Nakdong estuary toll a heavy socioeconomic cost. The paper investigates the influence of sediments on the nitrogen eutrophication, being claimed as the primary cause of green tide. To measure the flux of nitrate at the sediments-water interface, sediment cores were taken in Jan., Mar., May and Sep., 2000 at Noksan located in the West-Nakdong river estuary. The dissolved oxygen was profiled and then the pore water was extracted in situ. Core samples were analyzed for their textural characteristics. Cores were incubated by a novel technique to measure the fluxes of nitrate $(NO_3^-)$ and ammonia $(NH_4^+)$ at the sediment-water interface. The dissolved oxygen was depleted usually within several millimeters in the top sediments. Nitrate started to decrease drastically at the layer where dissolved oxygen was nearly depleted. Nitrate was also exhausted within several centimeters, followed by ammonia build up rapidly. The flux at the sediments-water interface calculated from the pore water concentrations revealed that nitrate was removed from the water column into the sediments. The sediment incubation experiment confirmed the above result. On the other hand ammonia were released from the sediment to the water column. As the incubation went on, however, the nitrate concentration in the overlying water was dropped below that of a top sediment. Then the flux is reversed, i.e., nitrate was released from the sediments to the water column. The implication is that the sediment can supply nitrate to the water column if it falls below a certain level. Thus it is likely that sediments in the eutrophicated river buffers the nitrate concentration in the water column, which leads to a prolonged green tide.

• 한국수자원학회논문집
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• 제49권12호
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• pp.971-980
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• 2016

일반적으로 배사에 비해서 준설은 경제적 부담이 크기 때문에 배사를 효율적으로 운영하는 것이 중요하다. 본 연구에서는 2차원 하상변동 모형인 Nays2DH를 이용하여 홍수기 운영수위에 따른 배사효율을 낙동강에 위치한 달성보를 중심으로 분석하였다. 분석결과, 가동보의 수 만큼 배사수가 형성되었으며, 배사수로 상류에는 퇴적이 발생하는 것으로 나타났다. 또한, 홍수기 운영수위를 EL. 14.5 m로 운영하는 것이 EL. 14.0 m로 운영하는 것에 비해서 배사효율이 약 4.6% 증가하여 퇴사가 약 4.5% 감소하는 것으로 나타났다. 본 연구에서 분석한 홍수기 운영수위에 따른 배사효율의 변화를 고려한다면, 저수지 퇴사 저감 및 준설주기의 장기화가 가능할 것으로 판단된다.

• 한국해양학회지:바다
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• 제7권4호
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• pp.247-256
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• 2002

평택화력발전소 취수구 주변 해역에서 세립질퇴적물의 운반양상을 규명하기 위하여 표층퇴적물과 부유퇴적물에 대한 모니터링을 실시하였다. 표층퇴적물은 동계에는 상대적으로 개방된 북측해역에서 조립하고 남측해역에서 세립한 반면. 하계에는 조석의 영향에 따라 서측해역에서 조립하고 동측해역에서 세립한 퇴적상의 변화를 보인다. 부유퇴적물의 농도는 동계에 높고 하계에 낮았으며, 표층수보다는 중.저층수에서 높은 농도를 보였다. 또한 조석에 따라서는, 조류의 비대칭성에 따라 육지 방향으로 이동되는 양이 바다 방향으로 이동되는 양에 비해 뚜렷하게 많았으며, 낙조에서 창조로 바뀌는 수심이 낮은 창조 초반에 급격히 증가하는 양상을 보였다. 장.단기간에 걸쳐 관측된 부유퇴적물의 순이동률은 3.4$\times$$10^{-3}$ kg.m$^{-2}$ .s$^{-1}$～5.7$\times$$10^{-3}$ kg.m$^{-2}$ .s$^{-1}$범위로 육지쪽 취수구 방향으로 이동되었다. 이와 같은 현상은 취수구 주변에서 육지쪽으로 발생되는 인위적인 흐름과 주변의 인공구조물에 의해 조류의 순환양상이 변화되었기 때문으로 해석된다.

• 한국초전도ㆍ저온공학회논문지
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• 제21권2호
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• pp.31-35
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• 2019

Andong-dam was built up in 1967 and it is one of the biggest dams in Korea. Previous studies showed that the sediments are highly contaminated with heavy metals such as arsenic, cadmium, and lead. Many research projects are going on to find out the source of the contamination, to evaluate the toxicities to ecosystem, to estimate the volume of sediment to be treated and to find out a good remediation method. Reports show that the sediment is highly contaminated and the main contamination source is supposed to be abandoned mines and a zinc refinery located upper stream of the river. A magnetic separation has been tested as a treatment method for the dredged sediment. Lab scale test showed that the magnetically captured portion is about 10% in weight but the contamination of heavy metal is much higher than the contamination of the passed portion. This indicates that a magnetic separation could be applied for the purpose of reduction of sediment to be treated and for increasing the volume of low toxic sediments which can be dumped as general waste. A magnetic separation using a HGMS has been tested for the sediment with variable magnetic field and the results showed the higher magnetic field increase the captured portion but the concentrating effect of heavy metal was weakened. Further study is needed to establish a useful technology and optimization between decontamination and reduction of sediment volume.

• 한국농공학회지
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• 제35권1호
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• pp.50-58
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• 1993

The sedimentation patterns at a reservoir, important to the reservoir capacity curve were simulated using a depth averaged, two-dimensional sediment transport model, that is capable of depicting velocity distributions and sediment transportation. The Banweol reservoir, whose stage capacity relationships have been surveyed before and after the construction, was selected and the daily inflow rates and stages were simulated using a reservoir operation model(DI-ROM). The applicability of the transport model was tested from the comparisons of simulated sedimentation patterns to the surveyed results. The simulated inflow rates and water level fluctuations at the reservoir during twenty-one years from 1966 to 1986, showed that water levels exceeding 80 percent of the total capacity occurred for 70 percent of the periods and inflow rates less than 5000rn$^3$/day sustained for 54 percent of the spans. Dorminant flow directions were simulated from two streamflow inlets to the dam site. And simulated sediment concentrations were higher near the inlets and lower at the inside of the reservoir. Sediment was deposited heavily near the inlets, and portions of sediments were distributed along the flow paths within the reservoir. The comparisons between the simulation results and the surveyed depositions were partially matched. However, it was not possible to compare two results at the upper parts of the reservoir where dredging was carried out few times for the purpose of reservoir maintenance. This study demonstrates that sedimentation patterns within the reservoir are closely related to incoming sediment and flow rates, water level fluctuations, and flow circulation within the reservoir.

• 한국수산과학회지
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• 제34권3호
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• pp.245-253
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• 2001

곰소만 조간대에서 채취한 표층퇴적물에 대하여 입도분석을 수행하여 퇴적물의 조직 특성을 분석하였다. 코어 시료를 이용하여 퇴적물의 수리-역학적 특성을 실험적으로 도출하였으며, 퇴적물의 심도별 역학적 응력 및 과잉간극수압, 그리고 지반의 안정성을 수치해석적으로 분석하여 바지락 양식장 퇴적물의 거동 특성을 규명하였다. 곰소만 조간대내의 표층 퇴적물은 겨울에는 $5 \phi$의 조립 실트가 주를 이루는 단모드형을 나타내고, 여름에는 $5 \phi$의 조립 실트질 퇴적물에 $4 \phi$의 미세사질 퇴적물이 첨가된 경향을 보여준다 바지락 양식장의 퇴적환경은 평균 입도 $4\~5 \phi$범위, 모래함량 $50\%$ 미만, 니질 함량 $5\sim10\%$ 범위를 나타낸다. 퇴적양상은sandy silt이며, 분급도는 $1.0\sim2.0 \phi$를 나타내고, 왜도는 0.1-0.5의 범위에 포함되어 퇴적물의 퇴적 작용이 방해가 될만한 높은 에너지 상태가 지속되지 않는 환경이 바지락 양식에 양호한 것으로 조사되었다. 수치해석적 결과를 토대로 볼 때, 바지락 양식에 양호한 저질환경은 사질과 니질이 혼합되어 절대 투수계수가 $10^{-11}\sim10^{-12}m^2$ 범위인 경우로 사료되며, 수치해석 모델링 견과 니질 피복층의 두께가 4cm를 초과하게되면 바지락 서식에 대한 저질환경은 크게 저하되고 있는 것으로 고찰된다.

• 자원환경지질
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• 제27권6호
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• pp.579-592
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• 1994

A case study is presented where a fluvial system is modeled in three dimensions and compared to data gathered from a study of the Arkansas River. The data is unique in that it documents changes that affected a straight channel that was excavated within the river by the U.S. Army Corps of Engineers. Excavation plan maps and sequential aerial photographs show that the channel underwent massive deposition and channel migration as it returned to a more natural, meandering path. These records illustrate that stability of fluvial system can be disrupted either by catastrophic events such as floods or by subtle events such as the altering of a stream's equilibrium base level or sediment load. SEDSIM, Stanford's Sedimentary Basin Simulation Model, is modified and used to model the Arkansas River and the geologic processes that changed in response to changing hydraulic and geologic parameters resulting from the excavation of the channel. Geologic parameters such as fluid and sediment discharge, velocity, transport capacity, and sediment load are input into the model. These parameters regulate the frequency distribution and sizes of sediment grains that are eroded, transported and deposited. The experiments compare favorably with field data, recreating similar patterns of fluid flow and sedimentation. Therefore, simulations provide insight for understanding and spatial distribution of sediment bodies in fluvial deposits and the internal sedimentary structure of fluvial reservoirs. These techniques of graphic simulation can be contributed to support the development of the new design criteria compatible with natural stream processes, espacially drainage problem to minimize environmental disruption.

• 한국수산과학회지
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• 제24권1호
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• pp.9-20
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• 1991

광양만에 분포하는 미고결 퇴적충의 물성특성을 Core 시료를 채취하여 분석하였다 퇴적상태의 특성을 지시하는 퇴적층의 공극율이 퇴적깊이에 따라 일정한 변화를 나타내지 않으며, 이는 자체하중에 의한 자연적 압밀이 매우 미세한 것을 나타내고 있다. 조석에 의한 해수면 변동이 퇴적층 거동에 미치는 영향을 수치해석적으로 분석한 결과, 퇴적층에 형성되는 공극수압이 이토층의 낮은 투수계수에 기인하여 해수면 변동에 따른 표층 수압변화보다 느리게 진행되고 있다. 따라서, 최소 해수면시점에 발생되는 공극수압이 해수압에 의한 역학적 응력보다 커서 퇴적층의 유효응력이 인장력으로 반전되며 일정깊이에서의 현장유효응력도 인장력상태(quick sand condition)인 것으로 나타난다. 이러한 현상은 퇴적물조직의 재구성이 내부적으로 발생될 수 있는 가능성을 제시해 주고 있다. 모래질이토층(sandy mud layer)이 이토층내에 존재할 경우에도 이토층과의 경계부분에서 인장력강태의 현장유효응력(quick sand condition)이 발생한다. 이는 퇴적물 재구성작용에 의해 모래질 입자가 표층에서 하부층으로 하강될 수 있는 역학적 이론근거를 제시해 주고 있으며, 본 연구결과에 의하면 모래질 입자들이 약 40cm 깊이에 하강될 때까지 quick sand condition이 형성된다.

• 대한환경공학회지
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• 제32권11호
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• pp.995-1000
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• 2010

하천 퇴적물 중 PCBs 농도수준 파악과 발생원 추정을 위해 낙동강 수계를 대상으로 21개 지점을 선정하고 지점당 3개씩 총 63개의 샘플을 분석한 결과 퇴적물 표층에서 검출된 DL-PCBs 농도분포는 3.0~6,600(평균440) pg/g-dry의 범위였고 TEQ값은