• 한국해양학회지:바다
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• 제9권4호
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• pp.153-163
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• 2004

In order to estimate the nutrient flux of the Seomjin River into the coastal waters of South Sea, and to understand the estuarine reactions during mixing between river water and seawater, we collected surface water along the salinity gradient in the Seomjin River estuary from Mar. 1999 to Apr. 2001. We found that nitrate and silicate were delivered by fluvial input, while phosphate was, supplied from disposed wastes in the Gwangyang Bay. Mean annual flux of dissolved inorganic nitrogen (DIN), phosphate and silicate into the Gwangyang Bay was estimated 10.9 molesㆍsec$^{-1}$(4,820 tonnesㆍyr$^{-1}$), 0.07 molesㆍsec$^{-1}$(68 tonnesㆍyr$^{-1}$), 13.3 molesㆍsec$^{-1}$(11,747 tonnesㆍy$^{-1}$), respectively. An evident removal of phosphate, silicate and ammonium at the mid-salinity zone during the dry season was attributed to the active uptake of phytoplankton, and consequently nutrient flux into the Gwangyang Bay was low. Whereas, during the flood season in summer, conservative or additional distribution of the nutrients was observed in the estuary. As a rsult nutrient flux into the Gwangyang Bay was maintained high. High concentrations of chlorophyll a and the active removal of nutrient during the dry season at the mid-salinity zone suggest that nutrient distribution in the Seomjin River estuary was mainly controlled by biological processes and nutrient fluxes into the Gwangyang Bay might be significantly modified of by the primary production.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.1254-1258
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• 2005

Net outflow flux and unit load of pollutants were investigated at a paddy fields area(Soro-ri) with large-scaled plots on loam soil during irrigation seasons of $2001\~2003$. Water samples were collected, and inflow and outflow were .measured at $5\~10$ day intervals during non-storm periods and at $2\~6$ hours intervals during storm events. The average concentration of TP in percolated water was much smaller than that in irrigation and surface outflow water likely due to phosphorus absorption capacity of paddy soils. Net outflow flux in study area was significantly correlated with rainfall and surface outflow discharge. Nutrient flux from Paddy fields can be abated by reduction in outflow surface discharge.

• 한국물환경학회지
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• 제33권6호
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• pp.670-679
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• 2017

An experiment to study the effect of temperature, light, and dredging on release of nutrients downstream from Gongjicheon in the Uiam reservoir was carried out in the laboratory using sediments from different depths. At various water temperatures, dissolved total nitrogen was not released, but the average nutrient flux of dissolved total phosphorus was increased (0.034 at $15^{\circ}C$, 0.005 at $20^{\circ}C$, 0.154 at $25^{\circ}C$, $0.592mg/m^2/d$ at $30^{\circ}C$). Dissolved total phosphorous was released in controlled darkness. In contrast, in controlled light, the concentrations of dissolved total phosphorous and dissolved total nitrogen in the overlying water steadily decreased during the study period (70 d), because they were continuously consumed by the growth of photosynthetic algae. However, there was no significant relationship between water nutrient concentration, nutrient release, and the depth of the sediment. We concluded that the dredging of sediment would not affect the nutrient release rate of the sediment, because there were no significant differences in the nutrient concentrations released from the sediment. When the sediment was removed from the surface to 20 cm in depth, the nutrients were not transferred to the water body, implying that the sediment removal had little effect on secondary pollution.

• Ocean and Polar Research
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• 제29권4호
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• pp.349-366
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• 2007

Seasonal variations of various physicochemical components (temperature, salinity, pH, DO, COD, DOC, nutrients-silicate, DIN, DIP) and potential limiting factor for phytoplankton primary production were studied in the surface water of semi-enclosed Masan Bay. Seasonal variations of nutrient concentrations, with lower values in summer and winter, and higher in fall, are probably controlled by freshwater loadings to the bay, benthic flux and magnitude of occurrence of phytoplankton communities. Their spatial distributional patterns are primarily dependent on physical mixing process between freshwater and coastal seawater, which result in a decreasing spatial gradient from inner to outer part of the bay. In the fall season of strong wave action, the major part of nutrient inputs (silicate, ammonium, dissolved inorganic phosphorus) comes from regeneration (benthic flux) at sediment-water interface. During the summer period, high Si:DIN and Si:DIP and low DIN:DIP relative to Redfield ratios suggest a N- and secondarily P-deficiency. During other seasons, however, silicate is the potential limiting factor for primary production, although the Si-deficiency is less pronounced in the outer region of the bay. Indeed, phytoplankton communities in Masan Bay are largely affected by the seasonal variability of limiting nutrients. On the other hand, the severe depletion of DIN (relatively higher silicate level) during summer with high freshwater discharge probably can be explained by N-uptake of temporary nanoflagellate blooms, which responds rapidly to pulsed nutrient loading events. In Masan Bay, this rapid nutrient consumption is considerably important as it can modify the phytoplankton community structures.

• 한국환경과학회지
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• 제23권6호
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• pp.1049-1060
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• 2014

We investigated the spatiotemporal variations of dissolved inorganic nutrients along a saline gradient to estimate nutrient fluxes in the Seomjin River estuary during dry (March 2005, March 2006, March 2007, and March 2008) and rainy seasons (August 2005, July 2006, July 2007, and July 2008). Dissolved inorganic nitrogen concentrations were similar in the endmembers of freshwater for the rainy and dry seasons. In contrast, the concentrations of dissolved inorganic phosphate and silicate in the rainy season were approximately 2-3 times higher than those in the dry season. River discharge was approximately 10 times higher in the rainy season ($212m^3sec^{-1}$) than in the dry season ($21m^3sec^{-1}$). The fluxes of dissolved inorganic nitrogen, phosphate, and silicate were 2.91, 0.004, and 2.51 tons $day^{-1}$ in the dry season and 7.45, 0.421, and 30.5 tons $day^{-1}$ in the rainy season, respectively. Although the range of nutrient concentrations were similar to previous results from investigations in the Seomjin River estuary, the nutrient fluxes were differed according to river discharge for different survey periods.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(2)
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• pp.848-849
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• 2005

• BMB Reports
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• 제53권5호
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• pp.241-247
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• 2020

As an intracellular degradation system, autophagy is an essential and defensive cellular program required for cell survival and cellular metabolic homeostasis in response to various stresses, such as nutrient deprivation and the accumulation of damaged organelles. In general, autophagy flux consists of four steps: (1) initiation (formation of phagophore), (2) maturation and completion of autophagosome, (3) fusion of autophagosomes with lysosomes (formation of autolysosome), and (4) degradation of intravesicular components within autolysosomes. The number of genes and reagents that modulate autophagy is increasing. Investigation of their effect on autophagy flux is critical to understanding the roles of autophagy in many physiological and pathological processes. In this review, we summarize and discuss ways to analyze autophagy flux quantitatively and qualitatively with the use of imaging tools. The suggested imaging method can help estimate whether each modulator is an inhibitor or a promoter of autophagy and elucidate the mode of action of specific genes and reagents on autophagy processes.

• 대한환경공학회지
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• 제33권1호
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• pp.9-15
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• 2011

농업 및 위락용으로 유지용수를 공급받는 군산 미제저수지의 수질 및 퇴적물 오염현황을 파악하고 퇴적물용출, 비점 오염원 및 외부공급수 등 세가지 영양염 유입경로별 오염부하를 비교 분석하였다. 수질분석결과 하절기에 수질이 크게 저하되고 부영양화에 따른 녹조현상이 가장 활발히 나타났으며, 부영양화지수 TSI (secchi depth)는 53.6, TSI (chlorophyll-a)은 57.7 및 TSI (TP)도 56.7로 모두 50 이상의 부영양호 상태를 보였다. 퇴적물오염도 조사결과 조사시기(계절)별 퇴적물 총질소(T-N)함량, 총인(T-P)함량 및 유기물함량의 각 평균은 통계학적으로 유의한 차이가 없는 것으로 나타났으나 시료채취 지점별 평균은 유의한 차이를 나타내 공간적 변화가 뚜렷하였다. 반면, T-N 및 T-P 퇴적물용출율결과는 공간적변화보다 시기별 변화가 뚜렷하였다. 수질 및 퇴적물 데이터의 상관성분석결과, 수질 T-N은 퇴적물 T-N함량 및 퇴적물 유기물함량과 통계학적으로 유의한 상관관계가 있었으나 수질 T-P는 통계학적으로 상관성을 보이는 인자가 확인되지 않았고 퇴적물 영양염 용출율 역시 수질과 통계학적으로 상관성을 보이는 인자가 확인되지 않았다. 미제저수지내 유입경로별 영양염오염부하 산정결과, T-N의 경우 외부 공급수에 의한 오염부하가 월등히 높게 나타났고 T-P의 경우 퇴적물용출부하와 외부 공급수 유입부하는 유사하고 비점유입부하가 상대적으로 적게 나타났다. 미제저수지의 수질개선을 위해서는 영양염오염부하가 상대적으로 높은 외부 공급수(금강호 양수)에 대한 대책이 우선적으로 수립되어야 하며 아울러, 퇴적물로부터 T-P용출을 저감시키는 수질오염저감대책이 필요한 것으로 판단된다.

• Ecology and Resilient Infrastructure
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• 제10권3호
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• pp.85-96
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• 2023

국내 호소를 상류 저수지 (<0.3 psu), 하구 저수지 (0.3 - 2 psu), 기수성 석호 (>2 psu)로 분류하여 호소별 퇴적물 총질소 (T-N), 총인 (T-P) 농도의 차이를 일원분산분석 (ANOVA) 하였으며, 실험실 코어 배양법 (laboratory core incubation)을 이용해 송지호 (11.80 psu), 간월호 (0.73 psu), 장군 저수지 (0.08 psu)의 호기 (aerobic)와 무산소 (anoxic) 조건에서의 질소 및 인 용출량 (benthic nutrient flux)을 측정하였다. 국내 호소의 퇴적물 내 총질소와 총인 농도는 염분 농도가 다른 호소별로 유의한 차이가 있는 것으로 분석되었다 (p<0.05). 사후 검정 (post-hoc)을 통해 총질소의 경우 상류 저수지 (2,918 mg/kg)와 하구 저수지 (2,094 mg/kg)에서 유의한 차이를 확인하였고 (p<0.001), 총인의 경우 상류 저수지 (789 mg/kg)와 기수성 석호 (533 mg/kg)가 유의한 차이를 보였다 (p<0.01). 실험을 통해 산정된 NH₄⁺-N의 용출량은 간월호에서 가장 높게 나타났으며, 폐쇄성 수역인 물리적인 특성과 염분으로 인한 질산화의 저해 등에 의한 것으로 판단된다. NO₃^--N의 용출량은 호기 조건에서 염분이 높은 호소일수록 낮게 나타났으나 무산소 조건에서는 염분이 높은 호소일수록 용출량이 높게 관측되었고, 이는 염분이 질산화 및 탈질이 억제되었기 때문이다. PO₄^3--P의 경우 송지호, 간월호, 장군 저수지 순으로 용출량이 높게 나타나, 염분이 음이온 흡착 경쟁 등을 통해 인산염의 용출을 촉진시키는 것으로 조사되었다. 퇴적물의 용출량 산출 시 미생물 군집, 성장률, 산화, 환원, 영양염류의 결합 형태 등의 요인이 염분에 의해 영향을 받으므로 염분화 된 호소의 퇴적물 용출 조사 시 염분에 의한 영향을 고려해야 할 것으로 사료된다.

• Molecules and Cells
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• 제37권5호
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• pp.399-405
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• 2014

Autophagy targets cytoplasmic cargo to a lytic compartment for degradation. Autophagy-related (Atg) proteins, including the transmembrane protein Atg9, are involved in different steps of autophagy in yeast and mammalian cells. Functional classification of core Atg proteins in plants has not been clearly confirmed, partly because of the limited availability of reliable assays for monitoring autophagic flux. By using proUBQ10-GFP-ATG8a as an autophagic marker, we showed that autophagic flux is reduced but not completely compromised in Arabidopsis thaliana atg9 mutants. In contrast, we confirmed full inhibition of auto-phagic flux in atg7 and that the difference in autophagy was consistent with the differences in mutant phenotypes such as hypersensitivity to nutrient stress and selective autophagy. Autophagic flux is also reduced by an inhibitor of phosphatidylinositol kinase. Our data indicated that atg9 is phenotypically distinct from atg7 and atg2 in Arabidopsis, and we proposed that ATG9 and phosphatidylinositol kinase activity contribute to efficient autophagy in Arabidopsis.