• Ocean and Polar Research
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• v.26 no.2
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• pp.175-185
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• 2004

To delineate Late Pleistocene paleoceanographic change of the West Pacific, we analyzed the oxygen and carbon isotopic ratios of two planktonic foraminifera species (G. sacculifer and N. dutertrei) from a piston core (KODOS-313) taken from the West equatorial Pacific, and they are compared with the published results of the East Pacific (ODP site 847 and RC 11-210), in terms of relative amounts and mass accumulation rates of $CaCO_3$ and eolian component, back to marine isotopic stage (MIS) 6. Differences in oxygen and carbon isotope values between two foraminifear species ($0.75%_{\circ}$ in ${\delta}^{18}O$, $0.05%_{\circ}$ in ${\delta}^{13}C$) are less than those of the East Pacific ($1.30%_{\circ}$ in ${\delta}^{18}O$, $0.14%_{\circ}$ in ${\delta}^{13}C$), which indicates smaller vertical contrasts in both temperature and nutrient between mixing-zone and thermocline in the West Pacific. Strong deviation in${\delta}^{18}O$ of G. sacculifer from SPECMAP suggests the carbonate fraction of KODOS-313 was subjected to partial dissolution by bottom water under lysocline. Lower accumulation rates of $CaCO_3$ and eolian component during glacial times are likely due to low sedimentation rate (ave. 0.75 cm/1000 yr) combined with carbonate dissolution in KODOS-313 site. However, the high $CaCO_3$ contents during the glacial periods clearly follow the general pattern of equatorial Pacific ocean.

• Ocean and Polar Research
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• v.26 no.2
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• pp.231-243
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• 2004

Sequential extraction was carried out on twenty two subsamples of three ferromanganese crusts from three seamounts (Lemkein, Lomilik, and Litakpooki) near the Marshall Islands in the western Pacific. The extraction was designed to fractionate Fe-Mn crust forming elements into low defined groups: (1) exchangeable and carbornate, (2) Mn-oxide, (3) Fe-oxyhyd.oxide, and (4) residual fraction. X-ray diffraction result shows that target material were well removed by each extraction step except for CFA in phosphatized crusts generation. According to chemical analysis of each leachate, most of elements in the Fe-Mn crusts are bound with two major phases. Mn, Ba, Co, Ni, Zn, (Fe, Sr, Cu, and V) are strongly bounded with Mn-oxide $({\delta}-MnO_2)$ phase, whereas Fe, Ti, Zr, Mo, Pb, Al, Cu,(V, P, and Zn) show chemical affinity with Fe-oxyhydroxide phase. This result indicates that significant amount of Al, Ti, and Zr can not be explained by detrital origin. Ca, Mg, K, and Sr mainly occur as exchangeable elements and/or carbonate phase. Outermost layer 1 and inner layer 2 which are both young crusts generations are similar in chemical speciations of elements. However, some of Fe-oxyhydroxide bounded elements (Pb, Y, Mo, Ba, Al, and V) in phosphatized innermost layer 3 are released during phosphatization and incorporated into phosphate (Pb, Y, Mo, and Ba) or Mn-oxide phase (Al and V). Our sequential extraction results reveal that chemical speciations of elements in the hydrogenetic crusts are more or less different from interelemental relationship calculated by statistical method based on bulk chemistry.

• Ocean and Polar Research
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• v.26 no.2
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• pp.299-309
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• 2004

Conductivity-temperature-depth (CTD) data obtained along a meridional section in the eastern tropical Pacific in July 2003 have been analyzed to identify various water masses, and to examine the hydrographic structure and zonal geostrophic currents in the upper 1000 m. Water mass analysis shows the existence of subtropical and intermediate waters, characterized by layers of subsurface salinity maximum and minimum, originating from both hemispheres of the Pacific. Vertical section of temperature in the upper 200 m shows the typical trough-ridge structure associated with the zonal current system for most of the tropical Pacific. Water with the lowest salinity of less than 33.6 was found in the upper 30 m between $8.5^{\circ}N$ and $10.5^{\circ}N$ in a boundary zone between the North Equatorial Current and North Equatorial Countercurrent. Temporal changes in water properties observed at $10.5^{\circ}N$ over a period of 9 days suggest both the local rainfall and horizontal advection is responsible for the presence of the low-salinity water. Development of a barrier layer was also observed at $10.5^{\circ}N$. In the North Equatorial Current region a local upwelling was observed at $15^{\circ}N$, which brings high salinity and cooler subtropical water to the sea surface. A band of countercurrent occurs in the upwelling region between $13^{\circ}N$ and $15^{\circ}N$.

• Ocean and Polar Research
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• v.26 no.2
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• pp.351-360
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• 2004

To investigate latitudinal variations in the zooplankton community along the meridian line ($5^{\circ}N-12^{\circ}N$, $131.5^{\circ}W$), we measured temperature, salinity, nitrate, chlorophyll-a and zooplankton at depths above 200 m from July $10^{th}$ to $25^{th}$, 2003. For comparative analysis, data of the physico-chemical properties and chl-a were matched to the two sampling depths (surface mixed layer and thermocline depth-200 m) of zooplankton. Latitudinal differences in the mesozooplankton distribution were mainly influenced by divergence formed at a boundary line formed by currents of opposing directions, consisting of North Equatorial Current (NEC) and North Equatorial Counter Current (NECC). High concentrations of chl-a south of $9^{\circ}N$, caused by equatorial upwelling related nutrients, is thought to be affected by the role of this divergence barrier, supported by relatively low concentrations in waters north of $9^{\circ}N$. The latitudinal differences of the chl-a were significantly associated with the major groups of zooplankton, namely calanoid and cyclopoid copepods, appendicularians, ostracods, chaetognaths, invertebrate larvae, and others. And temperature significantly affected the latitudinal variation of radiolarians, siphonophores, salps and immature copepods. The latitudinal differences in the two factors, temperature and chl-a, which explained 71.0% of the total zooplankton variation, were characterized by the equatorial upwelling as well as the divergence at $9^{\circ}N$. The physical characteristics also affected the community structure and abundance of zooplankton as well as average ratios of cyclopoid versus calanoid copepods. The abundance of dominant copepods, which were consistent with chl-a, were often associated with the carnivorous zooplankton chaetognaths, implying the relative importance of bottom-up regulation from physical properties to predatory zooplankton during the study period. These results suggested that latitudinal distribution of zooplankton is primarily controlled by current-related divergences, while biological processes are of secondary importance in the northeastern Equatorial Pacific during the study period in question.

• Ocean and Polar Research
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• v.37 no.3
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• pp.201-209
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• 2015

To examine the effects of increased $CO_2$ concentration and seawater temperature on the photosynthesis and growth of forest forming Ecklonia cava (Laminariales, Phaeophyta), sporophytic discs and gametophytes were cultured under three $pCO_2$ concentrations (380, 750, 1000 ppm), four temperatures (5, 10, 15, $20^{\circ}C$ for sporophytes; 10, 15, 20, $25^{\circ}C$ for gametophytes), and two irradiance levels (40, $80{\mu}mol$ photons $m^{-2}s^{-1}$) for 5 days. Photosynthetic parameter values ($ETR_{max}$, $E_k$, and ${\alpha}$) were generally higher as sporophytic discs were grown under low temperature and increased $CO_2$ concentration at 750 ppm. However, photosynthesis of Ecklonia sporophytes was severely inhibited under a combination of high temperature ($20^{\circ}C$) and 1000 ppm $CO_2$ concentration at the two photon irradiance levels. The growth of gametophytes was maximal at the combination of 380 ppm (present seawater $CO_2$ concentration) and $25^{\circ}C$. Minimal growth of gametophytes occurred at enriched $pCO_2$ concentration levels (750, 1000 ppm) and high temperature of $25^{\circ}C$. The present results imply that climate change which is increasing seawater temperature and $pCO_2$ concentration might diminish Ecklonia cava kelp beds because of a reduction in recruitments caused by the growth inhibition of gametophytes at high $pCO_2$ concentration. In addition, the effects of increased temperature and $pCO_2$ concentration were different between generations - revealing an enhancement in the photosynthesis of sporophytes and a reduction in the growth of gametophytes.

• Ocean and Polar Research
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• v.36 no.4
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• pp.395-405
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• 2014

A 570 cm-long sediment core was retrieved at $9^{\circ}57^{\prime}N$ and $131^{\circ}42^{\prime}W$ in 5,080 m water depth from the northeast equatorial Pacific and its stratigraphy was established with $^{10}Be/^9Be$ and paleomagnetic measurements. Successive AF demagnetization reveals eight geomagnetic field reversals. In the reference geologic time scale, the eight reversal events correspond to an age of about 4.5 Ma. However, $^{10}Be/^9Be$-based age yields 9.5 Ma at a depth of 372 cm. Such a large discrepancy in determined ages is attributed to an extremely low sedimentation rate, 0.4 mm/kyr on average, of the study core and resultant loss or smoothing of geomagnetic fields. The composite age model reveals a wide range in the sedimentation rate - varying from 0.1 to 2.4 mm/kyr. However, the sedimentation rate shows systematic variation depending on sedimentary facies (Unit II and III), which suggests that each lithologic unit has a unique provenance and transport mechanism. At depths of 110-80 cm with a sedimentation rate of about 0.1 mm/kyr, ancient geomagnetic field reversal events of at least a 1.8 Myr time span have not been recorded, which indicates the probable existence of a hiatus in the interval. Such a sedimentary hiatus is observed widely in the deep-sea sediments of the NE equatorial Pacific.

• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.546-567
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• 2015

Silicone-based surfactants consist of a hydrophobic organosilicone group coupled to one or more hydrophilic polar groups, while the hydrophobic groups of hydrocarbon surfactants are hydrocarbons. Silicone surfactants have been widely used in many industrial fields starting from polyurethane foam to construction materials, cosmetics, paints & inks, agrochemicals, etc., because of their low surface tension, lubricity, spreading, water repellency and thermal and chemical stability. A wide range of silicone surfactant structures are required to provide the functional diversity for reflecting the necessities in the various applications. This review covers the basic properties and the synthetic schemes of polydimethylsiloxane and reactive polysiloxanes as hydrophobic siloxane backbones, the main reaction schemes, such as hydrosilylation reaction, for coupling reactive polysiloxanes to hydrophilic groups, and the synthetic schemes of the main polysiloxane surfactants including polyether-, ionic-, carbohydrate-type surfactants.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.113-121
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• 1999

Changes in lipid content, lipid class and fatty acid compositions of the cultured oysters in shallow-water, Bukman bay (Tongyeong, Korea), using both Korean and Japanese spats were investigated. The content of non-polar lipid (NL) comprised approximately $60- 80\%$ of total lipid (TL) in the cultured oysters. There was a positive correlation between NL content and meat weight, y=0.287lx-15.309 (r=0.834l, p<0.001). The prominent fatty acids of the oysters were 16:0, 20:5n-3 (eicosapentaenoic acid, EPA), 22:6n-3 (docosahexaenoic acid, DHA), 18:0, l8:1n-7, l8:1n-9, l6:1n-7, 14:0 and l6:4n-3. During the growth of the oysters, l6:4n-3 showed the highest coefficient of variation, accounting for $41.8\%$ for the Korean oyster and $32.3\%$ for the Japanese one, respectively. Both oysters showed low level of n-3 fatty acids such as DHA and EPA and high level of n-6 fatty acid, 20:4n-6, in the spawning period (August). During growth of the oysters, both EPA and DHA were the richest fatty acids in the harvest period (December, 314 mg/100g sample) and in the pre-spawning period (July, 237-247 mg/100g sample), respectively. Consequently, the cultured oyster with Japanese spat contained approximately two times more n-3 fatty acids per oyster individual than those with Korean one in the harvest season.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.1
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• pp.33-40
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• 1987

This paper aims to study the browning reactions of lipid originated carbonyl compounds with nitrogenous compounds in dried fishes, flounder, mackerel, shrimp, hair tail fish, and whale. The major fatty acids in the flounder, the mackerel, the shrimp, and the hair tail fish were $C_{16:0},\;C_{18:1},\;C_{22:5},\;C_{22:6}$, and those in the whale meat were $C_{16:0},\;C_{18:1},\;C_{20:4}$. The nonpolar lipid contained higher percent of $C_{18:1}$ while the polar lipid contained higher percent of $C_{22:6}$. When those fishes were dried and stored, the PoV and CoV were high in the mackerel and the hair tail fish, whereas low in the flounder, the shrimp, and, the whale. The browning was developed more rapidly in the lipid soluble fraction than in the water soluble fraction of each sample, and the loss of available lysine and polyenoic acids were accompanied. The polyunsaturated fatty acids markedly decreased, particularly, in phospholipid than in neutral lipid, and $C_{20:5},\;C_{22:5},\;C_{22:6}$ were rapidly decreased during the storage.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.355-358
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• 2010

Inductively coupled low temperature plasmas with oxygen, argon, mixture of oxygen and argon, and nitrogen have been used to modify polycarbonate(PC) films at the various process conditions. All plasma treatments generally had a tendency to increase the surface roughness of PC regardless of process conditions. The treatment of oxygen plasma showed the highest value in the surface roughness and mostly enhanced the generation of oxygen containing polar groups as much as 43% in comparison of untreated PC. The contact angle of untreated PC decreased from $82.31^{\circ}$ to the lowest value of $9.17^{\circ}$ after oxygen plasma treatment. The increase of RF delivered power had an effect on the rapid reduction of contact angle, but gas flow rates did not effect to reduce contact angles so much.