• 한국해양학회지:바다
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• 제14권1호
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• pp.1-9
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• 2009

2007년 8월에 동해에서 처음으로 $^{234}Th/^{238}U$ 비평형(disequilibrium)을 이용하여 유광대에서 심층으로의 입자상 유기탄소 침강플럭스(export flux)를 추정하였다. 입자상 유기탄소 침강플럭스는 $^{234}Th$ 침강 플럭스에 POC/$^{234}Th_p$ 비율을 곱하여 구하였으며, $^{234}Th$ 플럭스는 표층에서 수심 100 m까지 $^{234}Th/^{238}U$ 비평형을 적분하여 계산하였고 POC/$^{234}Th_p$ 비율은 수심 150 m와 200 m에서 채집한 부유물질 시료(입자크기가 0.7 ${\mu}m$이상)에서 측정하였다. 유기탄소 침강플럭스는 14-506 mg C $m^{-2}$ $day^{-1}$의 범위를 나타냈으며, 정점 A2에서 최고값을 보였고 정점 D4에서 최소값을 보였다. 유기탄소 침강플럭스는 유광대에서의 일차생산력과 매우 좋은 상관관계를 나타내었으며, 유기탄소 침강플럭스/일차생산력 비율은 0.29-0.62(평균 0.43)의 범위를 보였고, 연안역에 비해 심해역에서 다소 높은 비율을 나타냈다. 동해에서 관측한 유기탄소 침강플럭스는 전반적으로 대양에서 관측한 값들보다는 높았고 대륙 주변해에서 관측한 값보다 다소 높거나 유사하였다. 동해에서의 침강플럭스/일차생산력 비율은 북해(North Sea)와 척치해(Chukchi Sea)에서 관측한 값들과는 유사하였지만, 라브라도해(Labrador Sea), 바렌츠해(Barents Sea), 리온스만(Gulf of Lions)에서 관측한 값들보다는 월등히 높았다. 따라서 동해는 전세계 해역에서 유광대에서 생성된 유기탄소가 수심 200 m 이하 심층으로 가장 많은 비율로 침강하는 해역들 가운데 하나라고 생각된다.

• Ocean and Polar Research
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• 제44권3호
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• pp.221-233
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• 2022

A sediment trap had been deployed at 1250 m depth in the Eastern Tropical Pacific (ETP) from September 2009 to July 2010, with the aim of understanding the temporal and vertical variability of particle flux. During the monitoring period, total particle flux varied from 12.4 to 101.0 mg m^-2day^-1, with the higher fluxes in January-March 2010. Biogenic particle flux varied in phase with the total particle flux. The increase in total particle flux during January-March 2010 was attributed to the enhanced biological production in the surface layer caused by wind-driven mixing in response to the seasonal shifts in the location of the Intertropical convergence zone. The export ratio (e-ratio) was estimated using the particulate organic carbon flux and satellite-derived net primary production data. The estimated e-ratios changed between 0.8% and 2.8% (1.4±0.6% on average). The ratio recorded in the negative phase of Pacific decadal oscillation (PDO) was similar to the previous results obtained from the ETP during the 1992/93 periods in the positive phase of PDO. This suggests that the regime shift of the PDO is not related to the carbon export ratio.

• 한국해양학회지:바다
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• 제19권2호
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• pp.109-124
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• 2014

남극 아문젠해의 탄소순환을 이해하기 위해서 표층에서 심층으로의 입자상 유기탄소 침강플럭스를 ${\psi}$/${\psi}$ 비평형법을 이용하여 추정하였다. 2012년 2월과 3월에 걸쳐 남극 아문젠해의 총 14개 정점에서 깊이별로 해수시료를 채취하였고, 총 ${\psi}$, 용존 ${\psi}$ 및 입자상 유기탄소를 분석하였다. 수심에 따라 총 ${\psi}$의 활동도 농도는 ${\psi}$에 비하여 결핍과 과잉을 나타내었다. 유광대에서 총 ${\psi}$의 결핍 정도는 엽록소 및 형광도와 거울상을 나타내고, 질산염 제거와 수반되어 나타나므로 생물 활동의 영향으로 파악되었다. 심층에서 일어나는 총 ${\psi}$ 결핍은 Fe/Mn 산화물에 의해 이루어지는 것으로 해석되었다. 유광대 바로 아래의 수층에서 나타나는 총 ${\psi}$ 과잉은 재광물화 작용보다는 이 깊이에 집적된 입자상 ${\psi}$에 기인하였다. 정상상태 모델로 추정한 ${\psi}$의 침강플럭스는 평균 $867{\pm}246dpmm^{-2}day^{-1}$이었으며, 유광대에서 질소와 인의 결핍 총량과 밀접한 관련성을 보였다. 입자상 유기탄소와 ${\psi}$의 비율($7.08{\pm}4.27{\mu}molCdpm^{-1}$)을 이용하여 추정한 입자상 유기탄소의 침강플럭스는 평균 $5.9{\pm}3.9mmolCm^{-2}day^{-1}$으로 나타났는데 이 값은 2-3월의 웨델해와 유사한 수준이었다. 입자상 유기탄소 플럭스와 일차생산력의 비율로 나타낸 생물 펌프의 효율(ThE)은 3-54%(평균 28%) 범위였다.

• Journal of the korean society of oceanography
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• 제38권1호
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• pp.1-10
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• 2003

A time-series sediment trap was deployed at a depth of 1034 m in the eastern Bransfield Strait from December 25, 1998 to December 24, 1999. Particle fluxes showed large seasonal variation; about 99% of the annual total mass flux (49 g m/sup -2/) was collected during the austral summer and fall (January-March). Settling particles consisted primarily of biogenic silica, organic carbon, calcium carbonate, and lithogenic material. Biogenic silica and lithogenic material predominated settling particles, comprising 36% and 30% of the total mass flux, respectively, followed by organic carbon, 11% and calcium carbonate, merely 0.6%. The annual organic carbon flux was 5.4 g C m/sup -2/ at 1000 m in the eastern Bransfield Strait, which is greater than the central Strait flux. The relatively lower flux of organic carbon in the central Bransfield Strait may be caused by a stronger surface current in this region. Organic carbon flux estimates in the eastern Bransfield Strait are the highest in the Southern Ocean, perhaps because of the fast sinking of fecal pellets, which leads to less decomposition of organic material in the water column. Approximately 5.8% of the organic carbon produced on the surface in the eastern Bransfield Strait is exported down to 1000 m; this percentage exceeds the maximum EF/sub 1000/ values observed in the Atlantic and Southern Oceans. The eastern Bransfield Strait appears to be the most important site of organic carbon export to the deep sea in the Southern Ocean.

• 한국환경과학회지
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• 제21권10호
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• pp.1171-1179
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• 2012

Headwaters initiate material export to downstream environments. A nested headwater study examined the flux of dissolved constituents and water from a perennial stream and four ephemeral/intermittent streams in the Upper Gulf Coastal Plain of Mississippi. Water was collected during storm and baseflow conditions. Multiple linear regression was used to model constituent concentration and calculate flux. Event was the major source of water discharged from the ephemeral and intermittent streams however, baseflow was the major source for water discharged by the perennial stream during events. The perennial stream had an area weighted average yields of 10.1, 0.01, 1.03, 0.65 kg/ha/yr of DON (dissolved organic nitrogen), $NO_3^-$-N, $NH_4^+$-N and $PO_4^{-3}$, respectively while large variabilities existed between the ephemeral and intermittent streams. These findings highlight the importance of headwaters in protecting the low order drainage basins as a key to water quality within perennial streams.

• Journal of Korean Society for Atmospheric Environment
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• 제18권E2호
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• pp.85-95
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• 2002

Hydrogen peroxide and methyl hydroperoxide were measured over the northwestern Pacific Ocean during NASA's PEM (Pacific Exploratory Mission) -West. The first experiment (PEM -West A) was conducted in the fall of 1991 and PEM-West B in the early spring of 1994. Hydroperoxide data were obtained on board the NASA DC -8 aircraft through the entire depth of the troposphere. Average concentrations of both H$_2$O$_2$and CH$_3$OOH were higher during PEM -West A than B. The seasonal difference in hydroperoxide distribution was determined by the degree of photochemical activities and the strength and location of jetstream, which led to extensive and rapid continental outflow during the PEM-West B. While for H$_2$O$_2$distribution, a longitudinal gradient was more apparent than a latitudinal gradient, it was opposite for the CH$_3$OOH distribution. The longitudinal gradient indicates the proximity to the anthropogenic sources from the Asian continent, but the latitudinal gradient reflects photochemical activity. During PEM -West B, the ratio of C$_2$H$_2$/CO, a tracer for continental emission was raised and high concentrations of H$_2$O$_2$were associated with high ratios. The flux of hydroperoxide toward the North Pacific was also enhanced in the early spring. The eastward fluxes of H$_2$O$_2$ were 9% and 17% of the average photochemical production over the Pacific Basin between 140°E and 130°W during PEM-West A and B, respectively. For CH$_3$OOH, these ratios were 8% and 13%. Considering the lifetime of hydroperoxide and the rapid transport of pollutants, the export of hydroperoxide with other oxidants would have a significant influence on oxidant cycles over the North Pacific during winter/spring.

• 대한토목학회논문집
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• 제30권6B호
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• pp.551-560
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• 2010

본 연구에서는 현재 시행되고 있는 수질오염총량관리제 모니터링 시스템에 적용가능한 하천 오염부하량 추정기법을 제안하고 있다. 하도추적기능과 증발산량 계산 기능을 추가한 수정 TANK 모형을 이용하여 국립환경과학원에서 8일 간격으로 관측된 유량자료를 일 유량 자료로 확장하였다. 관측된 수질-유량 동시관측자료를 이용하여 7변수 대수선형모형의 매개변수를 최소분산 비편향 추정기법에 의해 추정하였다. 확장된 일 유량자료와 7변수 대수선형모형의 결과가 연계되어 관측지점별일 오염부하량이 계산되었다. 그 결과 SS, TN, TP 하천 오염부하량 추정에서 만족스러운 결과를 확인할 수 있었다. 적용의 일환으로 낙동강유역을 대표할 수 있는 SS, TN 및 TP 수질항목별 대표 단위면적당 부하량 유황곡선을 작성하였으며, 이를 통하여 낙동강 유역의 전체적인 하천오염부하량의 배출분포를 살펴보았다.

• 대기
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• 제24권2호
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• pp.141-150
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• 2014

This study investigates the characteristics of the Gross Moist Stability (GMS) over the tropics. The GMS summarizes the relationship between large-scale entropy forcing due to radiation and surface fluxes and the response of smaller-scale convection. The GMS is able to explain both to where moist entropy is advected by the atmospheric circulation and how deep the moisture flux convergence is in the tropical region. In the deep convective region, positive GMS appears over the warm pool region due to the strong column-integrated moisture convergence and the ensuing export of moist entropy to the environment. The vertical advection of moist entropy dominates over the horizontal advection in this region. Meanwhile, over the eastern tropical ITCZ region, which is characterized by shallow convective area, import of moist entropy by horizontal winds is dominant compared to the vertical moist entropy advection. Future changes in the GMS are also examined using the 22 CMIP5 model simulations. A decrease in the GMS appears widely across the tropics, but its increase occurs over the western-central equatorial Pacific. It is evident that the increased GMS region corresponds to an increased region of precipitation, implying that strengthened convection in the future due to increased entropy forcing exports the enhanced moist energy to stabilize the environment.