TaeKeun Rho

다학제적인 해양연구가 활발하게 수행됨에 따라 다양한 종류의 해양연구시설·장비가 매년 구입되고 있다. 그러나 해양 연구시설·장비 중, 환경자료 수집 및 시료채취 등에 사용하는 다양한 종류의 현장 관측장비들을 현재의 국가연구시설·장비 표준분류체계로 분류하여 관리하는 데 어려움이 있다. 한국해양과학기술원의 경우 미분류상태로 적절히 관리되지 않는 연구시설·장비가 약 30% 정도이다. 본 연 구에서는 해양 연구시설·장비를 특성에 따라 중분류군 7개와 소분류군 36개로 분류하고, 국가연구시설장비 표준분류체계에 의해 해양 연구시설·장비를 효율적으로 관리하기 위해 ‘환경관측/분석장비’라는 대분류군을 국가연구시설장비 표준분류체계에 추가하기를 제 안한다. 그리고 해양 연구시설·장비 중 실험실에서 운영하는 장비들은 기존의 국가연구시설장비 표준분류체계에 따라 분류할 것을 제 안한다. 이를 통하여 우리나라 전체의 해양관련 연구시설·장비를 체계적으로 분류하여 효과적으로 관리할 수 있을 것으로 기대한다. As multidisciplinary marine research is actively conducted, various types of marine research facilities and equipment are purchased every year. However, among marine research facilities and equipment, it is difficult to classify and manage various types of field observation equipment used for environmental data collection and sample collection under the current national research facility and equipment standard classification system. In the case of Korea Institute of Ocean Science and Technology...

해수 중 용존 암모늄 분석에는 Berthlot's 반응의 분광광도법이 일반적으로 사용되었으나, 최근에는 OPA (orthophthaldialdehydesulfite) 형광시약을 이용한 형광법이 국제적으로 활발하게 사용되고 있다. 본 연구에서는 2017년도 호주연구선 Investigator에서 수 행된 국제 영양염 선상 상호비교 실험에서 두 기관(KIOST(분광광도법, 1차 선형 회귀식 기울기만 사용), 호주CSIRO(형광법, 2차 비선형 회귀식 사용))간의 영양염 표준물질과 현장 해수시료의 용존 암모늄 농도값 차이(약 0.31 μM)의 원인을 이해하기 위해 분 석방법 간 검출한계, 분광광도법에 내재된 시약 굴절률, 검량선식 등에 의한 영향을 고찰하였다. 본 연구에서 측정된 분광광도법의 방법검출한계(0.063 μM)와 시약 굴절률 바탕값(0.054 μM)은 두 기관의 용존 암모늄 농도값 차이를 각각 20%, 17% 정도 설명할 수 있었다. 그러나 분광광도법의 검량선을 형광법과 동일한 2차식 또는 선형회기식의 기울기와 절편으로 농도를 계산할 경우, 두 기관 간의 용존 암모늄 농도값 차이는 현장에서 측정된 분광광도법의 방법검출한계 이하로 줄었다. 따라서 국제 영양염 선상 상호 비교 실험에서 영양염 표준물질과 해수 현장시료에서 나타난 두 기관 간의 용존 암모늄 농도값 차이는 분광광도법과 형광법의 분 석방법 차이에 의한 영향보다는 두 방법에 사용된 상이한 검량선식 영향인 것으로 판단된다. 향후 해수시료의 용존 암모늄 자료를 비교할 때 분석방법의 차이보다는 분석에 사용된 기저선, 표준용액열 개수, 검량선식 등에 대한 정보에 유의할 것을 권장한다. Berthlot's reaction spectrophotometric method is generally used for the analysis of dissolved ammonium in seawater, but in recent years, a fluorescence method using an ortho...

In Jeju Island, multiple land-based aquafarms were fully operational along most coastal region. However, the effect of effluent on distribution and behaviours of dissolved organic matter (DOM) in the coastal water are still unknown. To decipher characteristics of organic pollution, we compared physicochemical parameters with spectral optical properties near the coastal aquafarms in Jeju Island. Absorption spectra were measured to calculate the absorption coefficient, spectral slope coefficient, and specific UV absorbance. Fluorescent DOM was analysed using fluorescence spectroscopy coupled with parallel factor analysis. Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) were measured using high-temperature catalytic oxidation. The DOC concentration near the discharge outlet was twice higher than that in natural groundwater, and the TDN concentration exponentially increased close to the outlet. These distribution patterns indicate that aquafarms are a significant sourc...

The East Sea (Japan Sea), a small marginal sea in the northwestern Pacific, is ventilated deeply down to the bottom and sensitive to changing surface conditions. Addressing the response of this marginal sea to the hydrological cycle and atmospheric forcing would be helpful for better understanding present and future environmental changes in oceans at the global and regional scales. Here, we present an analysis of observations revealing a slowdown of the long-term deepening in water boundaries associated with changes of water formation rate. Our results indicate that bottom (central) water formation has been enhanced (reduced) with more (less) oxygen supply to the bottom (central) layer since the 2000s. This paper presents a new projection that allows a three-layered deep structure, which retains bottom water, at least until 2040, contrasting previous results. This projection considers recent increase of slope convections mainly due to the salt supply via air-sea freshwater exchange ...

Changing global temperatures may alter oceanic concentrations of both dissolved oxygen (DO), which reflects water quality, and nutrients, which are an essential factor for the growth and distribution of phytoplankton. The East Sea (Japan Sea) is often considered a “miniature ocean” and an ideal natural laboratory to estimate the impact of global climate change on the oceanic biogeochemical cycles, because of the East Sea’s physical dynamics. Thus, the monitoring of nutrients and DO concentrations in the East Sea may help predict the response of biogeochemical cycles in the global ocean to changing climate. We describe and discuss the history of studies on DO in the East Sea, the change in vertical structure of DO profiles, the trend of DO inventory in the bottom layer, and the controversy regarding future projections of DO in the bottom water mass. We also summarize the history of nutrient measurements in the region, the general structure of vertical nutrient profiles, the horizontal nutrient distribution pattern on isobaric surfaces, the seasonal nutrient flux through the Korea Strait, and the recent debate on nutrient dynamics in the East Sea. The results of the studies we examine suggest that the processes controlling the structures and inventories of DO and nutrients in the East Sea are very sensitive to global climate changes.

"Understanding the relationships between the distributions of organisms and oceanographic conditions was one of the major goals of the Southeastern Bering Sea Carrying Capacity (SEBSCC) study. As a part of SEBSCC, this study focused on the response of nutrients and primary production to the variations of physical conditions, the general distribution of primary production, and the dynamics of phytoplankton growth, and nutrient utilization over the middle shelf and shelf break regions. The concentration of nutrients and primary productivity were measured over the shelf during 1997-1999. Shipboard nutrient and iron addition experiments were conducted over the middle shelf and shelf break region of the southeastern Bering Sea shelf during 2000-2001. The variations in physical conditions strongly affected the distribution of nutrients in the surface euphotic layer as well as in the deep layer. The offshore transport of the middle shelf water at mid-depth over the outer shelf may pla...

ABSTRACT The time evolution data of the biogeochemical and physical properties of the water column in coastal area (East/Japan Sea) located off the east coast of Korea is obtained by the coastal monitoring buoy station (ESROB, East Sea Realtime Ocean Buoy), equipped with chlorophyll a fluorometer (WQM), current meter (ADCP), PAR sensors, and Dissolved Oxygen and temperature. In April 2011, the optically-derived fluorescence sensor was installed into the buoy station within upper layer (about 1 m water depth) with highly resolved time resolution (10 min.) to examine the variability of various timespan spectrum, which has periods from diurnal to monthly variation, on the chlorophyll a fluorescence. The fluorescence time-series data showed distinct low-frequency (spring and fall blooms which is a typical characteristic in East/Japan Sea) fluctuations ranging from 0.2 μg/l to 3.8 μg/l, including abnormal summer surface bloom event in the coastal region. The high chlorophyll concentration within upper layer in summer may be attributed to surface thin low salinity water with the relatively rich nutrients flowing along the east coast of Korea through Korea Strait. Surface chlorophyll a fluorescence estimated from WQM sensor well correspond to the chlorophyll concentration derived from in situ water samples, showing a relatively high correlation coefficient (r=0.78).

During most of the vegetation season from late May to early September, the large-sized diatom alga Proboscia alata forms local patches with high abundances and biomasses in different oceanographic domains of the eastern Bering Sea shelf. The average abundance and biomass of the species in these patches amounts to 0.7 × 106 cells/l and 5 g WW/m3, respectively, for the

ABSTRACT In situ primary production data collected during 1978–1981 period and 1997–2000 period were combined to improve understanding of seasonal and spatial distribution of primary production in the southeastern Bering Sea. Mean daily primary production rates showed an apparent seasonal cycle with high rates in May and low rates in summer over the entire shelf of the southeastern Bering Sea except for oceanic region due to lack of data. There was also an increasing trend of primary production rates in the fall over the inner shelf and the middle shelf. There was a decreasing trend of primary production rates between late April and mid-May over the inner shelf while there was an abrupt increase between late April and mid-May over the middle shelf and the outer shelf. In the shelf break region, there was an increasing pattern in late May. These suggest that there was a gradual progression of the development of the spring phytoplankton bloom from the inner shelf toward the shelf break region. There was also a latitudinal variability of primary production rate over the middle shelf, probably due to either spatial variations of the seasonal advance and retreat of sea ice or horizontal advection of saline water in the bottom layer. Annual rates of primary production across the southeastern Bering Sea shelf were 121, 150, 145, 110, and 84 g C m−2 yr−1 in the inner shelf, the middle shelf, the outer shelf, the shelf break, and oceanic region, respectively. High annual rates of primary production over the inner shelf can be attributed to continuous summer production based on regenerated nitrogen and/or a continuous supply of nitrogen at the inner front region, and to fall production. There were some possibilities of underestimation of annual primary production over the entire shelf due to lack of measurement in early spring and fall, which may be more apparent over the shelf break and oceanic region than the inner shelf, the middle, and the outer shelf. This study suggests that the response of primary production by climate change in the southeastern Bering Sea shelf can be misunderstood without proper temporal and seasonal measurement.