• Ocean and Polar Research
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• 제30권3호
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• pp.225-238
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• 2008

In order to investigate the effects of intertidal sediments on the nutrient cycle in coastal environments, the benthic fluxes of ammonium, nitrate, nitrite, phosphate, and silicate at two stations on the intertidal flat of Keunso Bay were determined during each season. The efflux of ammonium was observed at S1 and resulted from the diffusion of remineralized ammonium and acceleration caused by the bioirrigation of macrofauna. The influx of ammonium at S2 was probably due to nitrification in the water column. The influx of nitrate was observed at both stations during all seasons, indicating that the nitrate in the pore water was removed by denitrification. Vigorous bioirrigation led to the efflux of dissolved inorganic nitrogen (DIN) at S1, whereas the influx of DIN at S2 was predominantly caused by denitrification. Contrary to the diffusive and bio-irrigated release of remineralized phosphate from the sediment at S1, the influx of phosphate was observed at S2, which may be attributable to adsorption onto iron oxides in the aerobic sediment layer. Silicate, which is produced by the dissolution of siliceous material, was mostly released from the sediment by molecular diffusion and bioirrigation. However, the influx of silicate was observed at S2 during spring and winter, which was ascribed to adsorption by particulate matter or assimilation by benthic microphytes. The annual fluxes of DIN were 328 mmol $m^{-2}yr^{-1}$ at S1 and -435 mmol $m^{-2}yr^{-1}$ at S2. The annual fluxes of phosphate were negative at both sites (-2.8 mmol $m^{-2}yr^{-1}$ at S1 and -28.9 mmol $m^{-2}yr^{-1}$ at S2), whereas the annual fluxes of silicate were positive at both sites (843 mmol $m^{-2}yr^{-1}$ at S1 and 243 mmol $m^{-2}yr^{-1}$ at S2).

• 식물병연구
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• 제16권1호
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• pp.97-100
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• 2010

2009년 진주시 수곡면 딸기 노지재배 육묘 포장과 하동군 옥종면 촉성재배 시설하우스 딸기포장에서 병이 발생하였다. 병징은 잎에 수침상의 작은 반점이 서서히 생기면서 엽맥의 주위에 다각형의 모무늬 병반이 나타나고 노란색의 달무리가 형성하는 것이 특징이다. 병든 잎은 서서히 시들고 암갈색으로 말라 죽는다. YDC 배지 상에서 병원균의 균총은 노란색을 띤 오랜지 색소를 분비하며 둥근 콜로니를 형성하고 단극모를 가지고 있다. 딸기에 접종한 결과 병원성이 잘 나타났다. 이상과 같이 딸기에 발생한 병정, 병원균의 특징 및 병원성을 검정한 결과 Xanthomonas fragariae에 의한 딸기 세균성모무늬병으로 동정하였다.

• Ocean and Polar Research
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• 제25권4호
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• pp.653-662
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• 2003

Changes in the area of geo-ecosystem $(62^{\circ}09'S,\;58^{\circ}31'w)$ reflect climatic changes in the South Shetland Islands. Air temperature and deglaciation will increase. The ice-free space area at the SSSS 8- (ASPA 121) site has enlarged threefold during the last 21 years, thus creating conditions for inhabitation and succession. Wind, water and snow play important roles in transportation of geochemical components. They distribute nutrients, mineral substances, seeds, fragments of plants and animals, etc. Plant and animal colonization is patchy and it happens at random in an 'island' - like manner. The colonization pattern is dependant, to a high degree on physical factors. The newly uncovered ice-free areas are at first inhabited by a vascular plant known as the Deschampsia antarctica. The border of the land-oasis with Admiralty Bay is the place where the processes related to animal feeding at the sea and reproduction on the land take place. Bird colonies and pinniped lairs form centers of fertilization surrounded by high chemical gradients dependent on the direction of the flow of nutrients $(e.g.\;NH_4)$. During the last 25 years, the numbers of penguins in this region have decreased, and thus the amount of materials excreted on land has diminished. The numbers of fur seals change in multi-annual cycles, and their migration into this area is related to the E1 $Ni\~{n}o$ phenomenon. The numbers of elephant seals in the area did not change. Organic matter deposited by the sea onto the shore are a source of nutrients and deficient chemical elements on land. Mineral matter is washed out into the waters of Admiralty Bay. These processes change seasonally, and multi annually. Negative effects on the environment at Arctowski Station induced by man are slight, but noticeable nevertheless. Physical processes have the largest influence on the living conditions and distribution of plants and animals, and as a consequence, on the functioning of the geo-ecosystem in the coastal-shore zone of the Maritime Antarctic.

• Ocean and Polar Research
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• 제28권3호
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• pp.317-329
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• 2006

To assess the contamination status of organochlorine pesticides in the marine environment of Saemangeum, surface seawater and sediments were collected and analyzed. Organochlorine pesticides were widely distributed in the Saemangeum environment, with DDT, HCH and endosulfan II contamination being particularly prevalent. The overall concentrations of DDTs, HCHs, and endosulfan II in surface seawater were in the rage of 0.03-0.65ng/l (mean value: 0.36ng/l), 1.31-4.54ng/l (2.63 ng/l), and not detected (ND)-0.96ng/l (0.49ng/l), respectively. Among the target organochlorine pesticides, endosulfan II showed the hi띤est level at the river mouth flowing into the Saemangeum. Additionally, its negative gradient from the rivers to the outside and a good correlation with $NO_3^-$ indicate that endosulfan ll inflows to the Saemangeum through the river; this conclusion is also supported by the elevated levels of endosulfan II in sediments at the river mouth. In sediment, the concentration of DDTs, HCHs, CHLs, and endosulfan II were in the range of 0.05-1.96 ng/g, 0.03-0.31ng/g, 0.01-0.13ng/g, and ND-0.62ng/g, respectively. Levels of contamination in Saemangeum are relatively lower than the median concentrations previously observed at the Korean coastal regions and sediment quality guidelines suggested by NOAA (Long et at. 1995).

• Ocean and Polar Research
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• 제27권2호
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• pp.189-195
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• 2005

Several models predict large and potentially abrupt ocean circulation changes due to anthropogenic greenhouse-gas emissions. These circulation changes drive-in the models-considerable oceanic oxygen trend. A sound estimate of the observed oxygen trends can hence be a powerful tool to constrain predictions of future changes in oceanic deepwater formation, heat and carbon dioxide uptake. Estimating decadal scale oxygen trends is, however, a nontrivial task and previous studies have come to contradicting conclusions. One key potential problem is that changes in the historical observation network might introduce considerable errors. Here we estimate the likely magnitude of these errors for a subset of the available observations in the Southern Ocean. We test three common data analysis methods south of Australia and focus on the decadal-scale trends between the 1970's and the 1990's. Specifically, we estimate errors due to sparsely sampled observations using a known signal (the time invariant, temporally averaged, World Ocean Atlas 2001) as a negative control. The crossover analysis and the objective analysis methods are for less prone to spatial sampling location biases than the area averaging method. Subject to numerous caveats, we find that errors due to sparse sampling for the area averaging method are on the order of several micro-moles $kg^{-1}$. for the crossover and the objective analysis method, these errors are much smaller. For the analyzed example, the biases due to changes in the spatial design of the historical observation network are relatively small compared to the tends predicted by many model simulations. This raises the possibility to use historic oxygen trends to constrain model simulations, even in sparsely sampled ocean basins.

• Ocean and Polar Research
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• 제38권4호
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• pp.259-270
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• 2016

Sea Surface Salinity (SSS) observations from the Aquarius satellite in the East Sea show large systematic biases mainly caused by the surrounding lands and Radio Frequency Interferences (RFI) along the descending orbits on which the satellite travels from the Asian continent to the East Sea. To develop a technique for correcting the systematic biases unique to the East Sea, the least square regression between in situ observations of salinity and the reanalyzed salinities by HYCOM is first performed. Then monthly mean reanalyzed salinities fitted to the in situ salinities are compared with monthly mean Aquarius salinities to calculate mean biases in $1^{\circ}{\times}1^{\circ}$ boxes. Mean biases in winter (December-March) are found to be considerably larger than those in other seasons possibly caused by the inadequate correction of surface roughness in the sea surrounded by the land, and thus the mean bias corrections are performed using two bias tables. Large negative biases are found in the area near the coast of Japan and in the areas with islands. In the northern East Sea, data sets using the ascending orbit only (SCIA) are chosen for correction because of large RFI errors on the descending orbit (SCID). Resulting mean biases between the reanalysis salinities fitted to in situ observations and the bias corrected Aquarius salinities are less than 0.2 psu in all areas. The corrected mean salinity distributions in March and September demonstrate marked improvements when compared with mean salinities from the World Ocean Atlas (WOA [2005-2012]). In September, salinity distributions based on the corrected Aquarius and on the WOA (2005-2012) show similar distributions of Changjiang Diluted Water (CDW) in the East Sea.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1869-1873
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• 2008

An isolate from holothurians was identified as an eicosapentaenoic acid (EPA)-producing bacterium KMG427, which is characterized by EPA synthesis efficiency, by thin layer and gas chromatographic analyses. The EPA production was maximized to more than 10% of the total fatty acids by incubation at $4^{\circ}C$ after cell proliferation at $20^{\circ}C$. The isolated bacterium was categorized as Gram-negative, rod-shaped, aerobic, and motile with a single polar flagellum. According to phylogenetic analysis based on morphological and physiological specificities as an EPA-producing bacterium, the isolate KMG427 was found to belong to the genus Shewanella. The 16S rDNA of KMG427 was revealed to have 100% of sequence identity to that of S. hanedai CIP $103207^T$. Therefore, the isolate might be classified and identified as Shewanella sp. KMG427.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.5-10
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• 2009

A freshwater bacterium, designated $IMCC1713^T$, was isolated from a highly eutrophic artificial pond. Cells of the strain were Gram-negative, chemoheterotrophic, poly-$\beta$-hydroxybutyrate granule containing and obligately aerobic short rods that were motile with a single polar flagellum. The 16S rRNA gene sequence similarity analysis showed that the novel strain was most closely related to the species Roseateles depolymerans (96.3%), Mitsuaria chitosanitabida (96.2%), Ideonella dechloratans (96.2%), and Pelomonas saccharophila (96.1%) in the Sphaerotilus-Leptothrix group within the order Burkholderiales. Phylogenetic trees based on 16S rRNA gene sequences indicated that the isolate formed an independent monophyletic clade within the order Burkholderiales. The relatively low DNA G+C content (57.4mol%), together with several phenotypic characteristics, differentiated the novel strain from other members of the Sphaerotilus-Leptothrix group. From the taxonomic data, therefore, the strain should be classified as a novel genus and species, for which the name Inhella inkyongensis gen. nov., sp. nov. is proposed. The type strain of the proposed species is strain $IMCC1713^T$ (=KCTC $12791^T$=NBRC $103252^T$=CCUG $54308^T$).

• 한국미생물·생명공학회지
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• 제41권1호
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• pp.8-16
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• 2013

An agar-hydrolyzing marine bacterium, strain GNUM08120, was isolated from Sargassum fulvellum collected from Yeongil bay of East Sea of Korea. The isolate was Gram-negative, aerobic, motile with single polar flagellum, and grew at 1-10% NaCl, pH 5.0-8.0, and $15-37^{\circ}C$. G+C content and the predominant respiratory quinone were 46.13 mol% and Q-8, respectively. The major cellular fatty acids were Summed feature 3 (24.5%), $C_{16:0}$ (21.7%), and $C_{18:1}{\omega}7c$ (12.5%). Based on 16S rRNA gene sequence similarity and DNA-DNA hybridization analyses, strain GNUM08120 was identified as a novel subspecies of Alteromonas macleodii, designated Alteromonas macleodii subsp. GNUM08120. Production of agarase by strain GNUM08120 was likely repressed by the effect of carbon catabolite repression caused by glucose. The crude agarase prepared from 12-h culture broth of strain GNUM08120 exhibited an optimum pH and temperature for agarase activity at 7.0 and $40^{\circ}C$, respectively. The crude enzyme produced (neo)agarobiose, (neo)agarotetraose, and (neo)agarohexaose as the hydrolyzed product of agarose.

• 대기
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• 제21권1호
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• pp.109-121
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• 2011

This study revisits the definition of Changma, which is the major rainy season in Korea and corresponds to a regional component of the East Asian summer monsoon system. In spite of several decades of researches on Changma, questions still remain on many aspects of Changma that include its proper definition, determination of its onset and retreat, and relevant large-scale dynamical and thermodynamical features. Therefore, this study clarifies the definition of Changma (which is a starting point for the study of interannual and interdecadal variability) using a basic concept of air mass and front by calculating equivalent potential temperature (${\theta}_e$) that considers air temperature and humidity simultaneously. A negative peak in the meridional gradient of this quantity signifies the approximate location of Changma front. This front has previously been recognized as the boundary between the tropical North Pacific air mass and cold Okhotsk sea air mass. However, this study identifies three more important air masses affecting Changma: the tropical monsoon air mass related to the intertropical convergence zone over Southeast Asia and South China Sea, the tropical continental air mass over North China, and intermittently polar continental air mass. The variations of these five air masses lead to complicated evolution of Changma and modulate intensity, onset and withdrawal dates, and duration of Changma on the interannual time scale. Importantly, use of ${\theta}_e$, 500-hPa geopotential height and 200 hPa zonal wind fields for determining Changma onset and withdrawal dates results in a significant increase (up to~57%) in the hindcast skill compared to a previous study.