• Environmental Engineering Research
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• 제25권2호
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• pp.230-237
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• 2020

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄⁺-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

• 한국해안해양공학회지
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• 제5권3호
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• pp.240-249
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• 1993

여러 종류의 다양한 외력조건에 의해서 형성되는 부유사농도에 대한 종합적 해석을 수행하고, 부유사양 Flux의 산정에 있어서 매우 중요한 역할을 차지하는 확산계수와 기준점농도에 관한 실용적 평가식을 제안하였다. 부유사농도의 연직확산계수는 사연형상을 고려한 저부마찰속도 및 조도요소를 사용하여 계산되는 과동점성계수에 대해 명확한 비예관계가 성립됨이 확인되었다. 또한, 흐름이 파에 부가되었을 경우 발생하는 기준점농도의 저하현상은 파와 흐름의 공존영역에서 형성되는 사연의 비대칭성에 기인됨이 확인되었다.

• 분석과학
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• 제25권6호
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• pp.441-446
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• 2012

본 연구에서는 안동호 퇴적물 중의 총 수은, 메틸수은, 중금속 농도를 조사하고 퇴적물과 수체간의 수은 이동량을 산정하였다. 안동호 퇴적물 중 수은 농도는 2009~2011 년에 각각 $155.0{\pm}71.9$ ng/g, $211{\pm}62$ ng/g 및 $198{\pm}6.88$ ng/g이었으며, 메틸수은은 2009 년 및 2011 년에 각각 $1.85{\pm}1.09$ ng/g, $3.49{\pm}1.79$ ng/g이었고, 총수은에 대한 메틸수은의 분율인 %메틸수은은 $1.17{\pm}0.39%$ 및 $1.77{\pm}0.94%$로 나타났다. 퇴적물 중 아연, 카드뮴, 납, 구리의 농도는 644 mg/kg, 7.3 mg/kg, 67 mg/kg, 42 mg/kg 으로 모두 미국 국립해양대기청(NOAA, National Oceanic and Atmospheric Administration)에서 제시한 퇴적물 기준(SQGs, Sediment Quality Guidelines)중의 최소 무영향 농도(ERL, Effect Range Low) 수준을 초과하는 수준이었다. 안동호에서 퇴적물로의 수은 이동량은 83.7 $ng/cm^2{\cdot}$년, 퇴적물에서부터 수체로의 수은 확산속도는 1.24 $ng/cm^2{\cdot}$년으로 추정되었다.

• 한국해양학회지:바다
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• 제4권3호
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• pp.188-197
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• 1999

해수에서 퇴적층으로 향하는 우라늄 제거 과정과 플럭스를 연구하기 위해 1996년 10월 16일과 1997년 8월 25일에 천수만 입구지역에서 공극수와 해저상자(benthic chamber, BC) 내부시료를 채취하였다. 공극수로부터 추정된 우라늄 플럭스는 해수~퇴적물 경계면에서 0.112~0.566 mg/$m^2yr$ 이었으며, 해수에서 퇴적물로 제거되는 양상을 보였다. 황해 전체로는 $4.3{\sim}21.5{\times}10^7$ g/yr의 우라늄이 제거되며 이는 전지구적 제거 플럭스의 0.4~2.2%에 달하는 값이다. 같은 방법으로 추정된 영양영 플럭스는 암모니아성 질소 135.6 mmol/$m^2yr$, 질산성 질소 228.2 mmol/$m^2yr$, 인산염 36.8 mmol/$m^2yr$, 그리고 규산염 23.9 mmol/$m^2yr$로 공극수에서 저층 해수로 용출되고 있다. 공극수중 질산성 질소와 퇴적물 망간의 수직 분포도로부터 산화환원 경계층이 퇴적물 표충하 3~5 cm 깊이에 존재함을 추정할 수 있었다. BC를 이용한 인산염 플럭스는 28.5 mmol/$m^2yr$로서 공극수를 통한 추정값과 비슷하였다. 반면에 BC를 이용한 우라늄과 규산염 플럭스 추정치는 공극수에 의한 값보다 두 자릿수 정도로 큰 값을 나타내었다. 공극수내 농도 분포로부터 추정된 우라늄과 영양염의 플럭스 추정치가 BC를 통한 추정치보다 더욱 신뢰도가 높다고 판단된다.

• 한국항해항만학회지
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• 제35권4호
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• pp.323-334
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• 2011

Suspended and sinking particles were collected in austral summer during ODP Leg 119 to the Indian Ocean sector of the Antarctic Ocean. Field work was carried out at four sampling sites in Prydz Bay. Two of these sites were located in the Outer Bay, and two in the Inner Bay. At the four locations, a total of ten deployments of a sediment trap array were made. The concentrations of chlorophylls and their degradation products both in suspended and sinking particulate matter in Prydz Bay were analyzed using HPLC. Chlorophylls a and c were the dominant algal pigments both in suspended and sinking particles. Because of the abundance of fecal pellets at Site 740, the mean fluxes at 200 m averaged 6 fold greater than that at 50 m. This implies that a dense swarm of zooplankters, presumably large copepods and/or salps, may "feed and excrete" mainly in between 100-200 m depths at this site, closest to land in Prydz Bay. Interestingly, The flux of phaeophorbide a was generally similar in magnitude to that of chlorophyll a throughout the study areas. This is an evidence that materials escaping from near-surface regions in austral summer derive mainly from the gazing of zooplankters. "New production" from sediment-trapped CHL pigment fluxes in Prydz Bay was estimated using f-ratio of 0.15, ranging from 520 to $1,605\;{\mu}gC\;m^{-2}\;day^{-1}$.

• Ocean and Polar Research
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• 제32권2호
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• pp.145-156
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• 2010

This study investigated organic carbon fluxes in Ulleung Basin sediments, East Sea based on a chamber experiment and geochemical analyses. At depths greater than 2,000 m, Ulleung Basin sediments have high organic carbon contents (over 2.0%). Apparent sedimentation rates (ASR) calculated from excess $^{210}Pb$ activity distribution, varied from 0.036 to $0.047\;cm\;yr^{-1}$. The mass accumulation rates (MAR) calculated from porosity, grain density (GD), and ASR, ranged from 131 to $184\;g\;m^{-2}\;yr^{-1}$. These results were in agreement with sediment trap results obtained at a water depth of 2100 m. Input fluxes of organic carbon varied from 7.89 to $11.08\;gC\;m^{-2}\;yr^{-1}$ at the basin sediments, with an average of $9.56\;gC\;m^{-2}\;yr^{-1}$. Below a sediment depth of 15cm, burial fluxes of organic carbon ranged from 2.02 to $3.10\;gC\;m^{-2}\;yr^{-1}$. Within the basin sediments, regenerated fluxes of organic carbon estimated with oxygen consumption rate, varied from 6.22 to $6.90\;gC\;m^{-2}\;yr^{-1}$. However, the regenerated fluxes of organic carbon calculated by subtracting burial flux from input flux, varied from 5.87 to $7.98\;gC\;m^{-2}\;yr^{-1}$. Respectively, the proportions of the input flux, regenerated flux, and burial flux to the primary production ($233.6\;gC\;m^{-2}\;yr^{-1}$) in the Ulleung Basin were about 4.1%, 3.0%, and 1.1%. These proportions were extraordinarily higher than the average of world open ocean. Based upon these results, the Ulleung Basin might play an integral role in the deposition and removal of organic carbon.

• 한국환경과학회지
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• 제18권11호
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• pp.1299-1307
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• 2009

In order to measure in-situ suspended particle size, volume concentration of suspended particulate matter and current speed, mooring observation was performed at the Gwangyang Bay by using of an optical instrument, 'LISST-100' and an acoustic instrument, 'ADV'(St. S1). And the sediment flux was obtained based on the concentration of suspended particulate matter and current speeds measured at three lines of Gwangyang Bay during ebb and flood tide of August 2006. To investigate the spatial variation of suspended particulate matter, profiling observations were measured difference echo intensity and beam attenuation coefficient by using of ADCP and Transmissometer (Line A, B, C). The suspended sediment flux rate at the mouth of Gwangyang Bay was observed to be higher during asymmetrical than symmetrical of current speeds. The flux of suspended particulate matter concentration and current speeds were transported to southeastern direction of surface layer and northwestern direction of bottom layer at the western area at line A of Gwangyang Bay. Small suspended particles have been found to increase attenuation and transmission more efficiently than similar large particles using acoustic intensity (ADV/ADCP) or optical transmit coefficient (LISST-100/Transmissometer). The application and problems as using optical or acoustic instruments will be detected for use in time varying calibrations to account for non-negligible changes in complex environments in situ particle dynamics are poorly understood.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.385-395
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• 2011

Time-series sediment traps were deployed at 1,000 m water depth of the northwestern subtropical Pacific from July 2009 to June 2010, with the aim of understanding temporal and spatial variations of sinking-particle fluxes. The opening and closing of the traps was synchronized at 18-day periods for 20 events. Total mass fluxes showed distinct seasonal variations with high values for the summer-fall seasons and relatively low values for winter-spring. This seasonal variation at two stations was characterized by a distinct difference in $CaCO_3$ fluxes between the two seasons. The enhanced $CaCO_3$ flux in the summer - fall seasons might be attributed to an increased planktonic foraminiferal flux. Total mass flux at FM10 station was nearly 50% higher than that at FM1 station. The difference in $CaCO_3$ fluxes between two stations contributed nearly 70% of the difference of total mass fluxes. The $CaCO_3$ flux was a major component controlling temporal and spatial variation of sinking - particle fluxes in the western subtropical Pacific Ocean.

• 생태와환경
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• 제42권4호
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• pp.413-421
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• 2009

Eleven lake sediment core samples were obtained and analyzed to develop a chronology using $^{137}Cs$ (in 1963) and two tephra layers (Ko-c2 in 1694 and Ta-a in 1739). Sedimentation rates estimated for the past ca 300 years in Lake Shirarutoro indicated that catchment development has influenced the shallowing process in the lake by increasing sediment production. The sediment yield under initial land-use development conditions for the first two periods was estimated as 514 tons $yr^{-1}$ from 1694 to 1739 and 542 tons $yr^{-1}$ from 1739~1963. The development of the Shirarutoro catchment intensified in the 1960s with deforestation and agriculture activity leading to an increased sediment yield of 1261 tons $yr^{-1}$ after 1963. The sediment yields after intensified land use development, such as forestry and agricultural development, were about 2 times higher than that under initial development conditions, leading to accelerated lake shallowing over the last ca 50 years. Sedimentation rates differed with location in the lake because of spatial variation in the sediment flux from the contributing rivers and their catchments. The sedimentation rates before 1963 were low in all sites except for one site close to the Shirarutoroetoro River. The sedimentation rate in 1739~1963 was accumulated mostly at the inflow of the Shirarutoroetoro River by sediment production associated with forestry for charcoal production and initial agricultural development. The sedimentation rate after 1963 increased. In particular, the southern zone of the lake near the conjunction with the Kushiro River had a high sedimentation rate, which is attributable to sediment inflow back from the Kushiro River during floods.

• Ocean and Polar Research
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• 제24권2호
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• pp.123-134
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• 2002

Seasonal variations of settling particles and metal fluxes were monitored at a nearshore site of Marian Cove, King Geroge Island, Antarctica from 28th February 1998 to 22nd January 2000. Near-bottom sediment traps were deployed at 30m water depth of the cove, and sampling bottles were recovered every month by SCUBA divers. Total particulate flux and metal concentrations were determined from the samples. Total particulate flux showed a distinct seasonality, high in austral summer and low in austral winter: the highest flux $(21.97g\;m^{-2}d^{-1})$ was found in February of 1999, and the lowest $(2.47g\;m^{-2}d^{-1})$ in September of 1998, when sea surface was frozen completely. Lithogenic particle flux accounted for 90% of the total flux, and showed a significantly negative correlation with the thickness of snow accumulation around the study site. It was suggested that the most of the lithogenic particles trapped in the bottles was transported by melt water stream from the surrounding land. Fluxes of Al, Fe, Ti, Mn, Zn, Cii, Co, Ni, Cr, Cd, and Pb showed similar seasonal variations with the total flux, and their averaged fluxes were 34000, 9000,960, 180, 13.8, 17.6, 3.0,2.1, 5.4, 0.02, and $1.5nmol\;m^{-2}d^{-1}$ respectively. Among the metals, Cu and Cd showed the most noticeable seasonal patterns. The Cd flux correlated positively with the fluxes of biogenic components while the Cu flux correlated with both the lithogenic and biogenic particle fluxes. The Cu flux peak in the late summer is likely related to a substantial amount of inflow of ice melt water laden with Cu-enriched lithogenic particles. On the other hands, the Cd flux peak in the early spring may be associated with the unusually early occurred phytoplankton bloom.