• Ocean and Polar Research
• /
• v.33 no.1
• /
• pp.21-34
• /
• 2011

We determined potential meso-scale benthic-pelagic ecosystem coupling in the north equatorial Pacific by comparing surface chl-a concentration with sediment bacterial abundance and adenosine triphosphate (ATP) concentration (indication of active biomass). Water and sediment samples were latitudinally collected between 5 and $11^{\circ}N$ along $131.5^{\circ}W$. Physical water properties of this area are characterized with three major currents: North Equatorial Current (NEC), North Equatorial Count Current (NECC), and South Equatorial Current (SEC). The divergence and convergence of the surface water occur at the boundaries where these currents anti-flow. This low latitude area ($5{\sim}7^{\circ}N$) appears to show high pelagic productivity (mean phytoplankton biomass=$1266.0\;mgC\;m^{-2}$) due to the supplement of high nutrients from nutrient-enriched deep-water via vertical mixing. But the high latitude area ($9{\sim}11^{\circ}N$) with the strong stratification exhibits low surface productivity (mean phytoplankton biomass=$603.1\;mgC\;m^{-2}$). Bacterial cell number (BCN) and ATP appeared to be the highest at the superficial layer and reduced with depth of sediment. Latitudinally, sediment BCN from low latitude ($5{\sim}7^{\circ}N$) was $9.8{\times}10^8\;cells\;cm^{-2}$, which appeared to be 3-times higher than that from high latitude ($9{\sim}11^{\circ}N$; $2.9{\times}10^8\;cells\;cm^{-2}$). Furthermore, sedimentary ATP at the low latitude ($56.2\;ng\;cm^{-2}$) appeared to be much higher than that of the high latitude ($3.3\;ng\;cm^{-2}$). According to regression analysis of these data, more than 85% of the spatial variation of benthic microbial biomass was significantly explained by the phytoplankton biomass in surface water. Therefore, the results of this study suggest that benthic productivity in this area is strongly coupled with pelagic productivity.

• Ocean and Polar Research
• /
• v.28 no.4
• /
• pp.467-473
• /
• 2006

The EM 120, a newly installed multibeam echo sounder on RM Onnuri, has several advantages over the previously installed SeaBeam 2000 in performance and thus data quality. The EM 120 system provides a bottom topographic map with high resolution by (1) increasing the number of beams, (2) increasing the across track swath range, (3) measuring the more accurate sound velocity within the water column, and (4) improving stabilization for pitching, rolling, and yawing of the ship. This study compares EM 120 and SeaBeam 2000 echo sounders in terms of the data quality from the same survey area in the Clarion-Clipperton Zone, NE Pacific. Our result shows that the EM 120 provides more precise topographic data than the SeaBeam 2000. Although overall trends of data, such as topographic direction and relief, are similar for both echo sounders, the water depths measured by the EM 120 are shallower than that of SeaBeam 2000 by 80 to 90 meters.

• Proceedings of the Korean Environmental Sciences Society Conference
• /
• 2003.11a
• /
• pp.145-150
• /
• 2003

16 APEX floats, autonomous profiling floats deployed as part of the Array for Real-time Geostrophic Oceanography (ARGO) program, are used to understand the currents at 800 m underwater in the southwestern East Sea. The flow penetrates into the Ulleung basin (UB) through two paths： an extension of the southward flowing the North Korean Cold Water along the east coast of Korea and between Ulleung Island and Dok island. Flows at 800 m are observed range 0.2 to 4.29 cm/sec and the variability in the north in the DB is stronger than that in the south. The eddy kinetic energy is found a few $cm^{2}$ $S^{-2}$. In the UB, cyclonic flows from 0.3 - 1.6 cm/see are observed with the bottom topography.

• Journal of the Korean Professional Engineers Association
• /
• v.38 no.2
• /
• pp.44-47
• /
• 2005

Recently, there are severe tension between Korea and Japan around Dokdo area. Because the marine resources near Dokdo are much plentiful. Especially, development of deep sea water and natural gas are hopeful in this area. In order to preoccupy a development plan of marine resources, many scientific investiment for ocean research are needed. We must have continuous concern about marine resources near Dokdo area.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.3
• /
• pp.113-116
• /
• 2007

We investigated the characteristics of various Tofu coagulants extracted from sea tangle using treated deep ocean water (DOW) as the solvents. The coagulants were typical solutions extracted from sea tangle using raw DOW and strongly electrolyzed acidic (SAC) or alkaline (SAK) water. The total dissolved solids (TDS), NaCl and electric conductivity were increased in the coagulant solution extracted by SAC than the others. In the coagulant solutions extracted by acidic electrolyzed solvent, aspartic acid content (13.5 mg/100 g) was higher than others (11.2 and 12.1 mg/100 g). The Tofu obtained using coagulants extracted with treated DOW had the water contents ranging from 79.55% to 80.04%. The contents of crude protein (12.1 g/100 g) and Na, Ca, K and Mg were relatively higher than general Tofu commercially available. Therefore, coagulant solutions extracted from sea tangle using treated DOW can be used to develop natural high-grade tofu for practical use.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.3 no.4
• /
• pp.214-227
• /
• 1998

This study was carried out to investigate the composition and diagenesis of the carbonate rocks from the seamounts in the Federated States of Micronesia, Central Pacific. Most of the samples were dredged from the water depth of about 1000-3000 m mainly in Chuuk Island, Hunter Bank, Caroline Ridge and Yap Trench. The carbonate rocks are either pelagic sediment mainly of planktonic foraminifera or shallow-marine sediment of corals, calcareous algae, mollusks and echinoderms. The rocks are altered texturally and chemically, except for those from the Hunter Bank and Yap A. The presence of shallow-marine cements suggests that the carbonate sediment has been subsided or reworked to the present water depth after deposition in shallow-marine environments. The texture of the carbonate sediment is reminiscent of meteoric diagenesis; however, the stable carbon isotopic composition of the altered rock samples shows affinity with that of sea water and the oxygen isotopic values are slightly enriched or same as compared to those of unaltered samples. These stable isotopic data suggest that the carbonate sediment of the study area has been diagenetically altered in the present deep-marine environment.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.13 no.3
• /
• pp.286-294
• /
• 2008

In order to understand the physical properties of deep-sea sediments, which mainly consist of pelagic red clays, sediment samples were collected at 24 stations using a multiple corer in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific. The sampled sediment cores were examined for the mass physical properties(i.e. grain size distribution, mean grain size, water content, specific grain density, wet bulk density, void ratio, and porosity) and the geotechnical properties(i.e. shear strength and consistency limits) with the content of biogenic opal and mineral composition. Although KR1 and KR2 areas on the same latitude are logitudinally far from each other, the mass physical properties of these areas are not distinctly different except for shear strengths. The maximum shear strength of surface sediments in KR2 area is higher than that in KR1 due to the appearance of a consolidated lower layer(Unit 3) in the sediment core from KR2.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2007.09a
• /
• pp.611-622
• /
• 2007

In the design and construction of the coastal/offshore structures, it is very important to evaluate the geotechnical characteristics of marine soils, which support the structures. Although the offshore site investigation is much more difficult than onshore, safe and precise jobs have not been accomplished in Korea because of the insufficiency of the test equipments especially for the site with deep water depth. The main objective of this study is to develop a new type of marine cone penetration testing(CPT) system, which can be utilized to even deep sea and high depth of soil layer. The system is one of seabed types and employs the conventional cone, which shows more reliable results than miniature cone. The most important parts of the marine CPT including continuous rod system, cone penetration system with wheel drive, automatic cone rod assembly/dissembly system etc., were designed and manufactured. Some tests to verify the developed marine CPT system were performed at both onshore and offshore sites as well as mechanical test in laboratory. The test results show the consistent and promising performance of the new equipment, and thereafter the system would be applicable to various sites with practical/economical advantages.

• Ocean and Polar Research
• /
• v.32 no.1
• /
• pp.15-22
• /
• 2010

Calcium carbonate ($CaCO_3$) content was measured from 3 box core (BC060301, BC060303, BC070301) sediments, in addition to pilot core (PC313) sediments, from deep waters within the Western Pacific Ocean. At the two collection sites (BC060301, PC313) located close to the equator, downcore variation exhibited low $CaCO_3$ content during the interglacial period and high $CaCO_3$ content during the glacial period. Variation of coarse fraction (>$63\;{\mu}m$) content also followed changes in $CaCO_3$ content, indicating that dissolution effect of bottom water decreased during the glacial period. Such variation pattern is typical of the Pacific Ocean. However, downcore variation at the two collection sites (BC060303, BC070301) in the Philippine Sea contrasted the trend of the previous two cores (i.e., high $CaCO_3$ content during the interglacial period and low during the glacial period). This pattern is typical of the Atlantic Ocean. Such results may be attributed to the increasing dilution effect, initiated possibly by the increased transportation of terrigenous materials from nearby continent and archipelago during the glacial period when sea level was low. Alternatively, it is possible that the non-carbonate biogenic particles may have been responsible for dilution. Because of these uncertainties, the record of $CaCO_3$ variation in the deep Western Pacific Ocean is not regionally consistent.

• Journal of the korean society of oceanography
• /
• v.39 no.1
• /
• pp.1-13
• /
• 2004

The Yellow Sea Warm Current (YSWC) and the Yellow Sea Cold Bottom Water (YSCBW) are two protruding features, which have strong influence on the community structure and distribution of zooplankton in the Yellow Sea. Both of them are seasonal phenomena. In winter, strong north wind drives southward flow at the surface along both Chinese and Korean coasts, which is compensated by a northward flow along the Yellow Sea Trough. That is the YSWC. It advects warmer and saltier water from the East China Sea into the southern Yellow Sea and changes the zooplankton community structure greatly in winter. During a cruise after onset of the winter monsoon in November 2001 in the southern Yellow Sea, 71 zooplankton species were identified, among which 39 species were tropical, accounting for 54.9 %, much more than those found in summer. Many of them were typical for Kuroshio water, e.g. Eucalanus subtenuis, Rhincalanus cornutus, Pareuchaeta russelli, Lucicutia flavicornis, and Euphausia diomedeae etc. 26 species were warm-temperate accounting for 36.6% and 6 temperate 8.5%. The distribution pattern of the warm water species clearly showed the impact of the YSWC and demonstrated that the intrusion of warmer and saltier water happened beneath the surface northwards along the Yellow Sea Trough. The YSCBW is a bottom pool of the remnant Yellow Sea Winter Water resulting from summer stratification and occupy most of the deep area of the Yellow Sea. The temperature of YSCBW temperature remains ${\leq}{\;}10^{\circ}C$ in mid-summer. It is served as an oversummering site for many temperate species, like Calanus sinicus and Euphaisia pacifica. Calanus sinicus is a dominant copepod in the Yellow Sea and East China Sea and can be found throughout the year with the year maximum in May to June. In summer it disappears in the coastal area and in the upper layer of central area due to the high temperature and shrinks its distribution into YSCBW.