• 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.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.7
• /
• pp.530-535
• /
• 2011

In this work, the adsorption characteristic of the composites by adding loess with aluminum ("Al-loess") and Loess with lanthanum ("La-loess") which have been developed to effectively remove phosphorus, the substance which causes the eutrophic lake has been evaluated. According to the result of the work, as the amount of aluminum or lanthanum put in 1g of loess increases, the combined amount also increases accordingly. When the loess with no aluminum or lanthanum attached was used, the rate of removing phosphorus was different in comparison with the case of using the composites of 0.5, 1 and 2 mg of aluminum and 0.5, 1 and 3 mg of lanthanum in each gram of loess. It was observed the amount required to remove 1 mg $PO_4^{3-}$-P/L of phosphorus completely is approximately 2 to 10 times less for the composite of Al-loess than loess alone. Also, in case of the composite of La-loess, the amount was decreased by about 1.5 to 10 times. In order to observe the rate of adsorption phosphorus with Al-loess and La-loess, the composites were used for the observation up to three times by water washing. As a result, the water washing of the composite did not affect phosphorus removal. According to the effect of pH, there is a high rate of removing phosphorus in the pH range of 5~8. It seems that the developed composite will effectively remove phosphorus when it is spread in the natural water system. Also, since Al-loess and La-loess composites are rapidly precipitated within 30 minutes, it is stabilized quickly at the bottom of the eutrophic lake and becomes responsible for the removal of phosphorus in water and eluted from the water and the sedimentary layer.

• Journal of the Mineralogical Society of Korea
• /
• v.27 no.3
• /
• pp.159-168
• /
• 2014

Holocene plaeoenvironmental changes were interpreted by grain size and mineral analyses of a piston core (HB 13-2), obtained along the western slope of the Hupo Basin, Korea. The core sediments are characterized by two discrete, sedimentary facies: upper unit (0-0.4 mbsf) dominated by bioturbation structures with weak lamination, and lower unit (0.4-3.3 mbsf) characterized by intensified bioturbation toward bottom. Analysis of sensitive grain size and sortable silt demonstrated that the inflow of the Tsushima Warm Current (TWC) into the Hupo Basin strengthen from the period of sediment deposition over 0.82 mbsf. The minerals of the core sediments are composed mainly of quartz, microcline, orthoclase, albite and clay minerals including chlorite, kaolinite and illite. No noticeable changes of the mineral percentage was observed according to the grain size and depth of the samples. The integral breadth (${\Delta}^{\circ}2{\theta}$) of clay minerals from 1.4 mbsf to top layer shows an increasing trend, which clearly means climate warming from the period of sediment deposition above 1.4 mbsf. This interval correlates with the Holocene climate optimum at Mid Holocene.

• Biomedical Science Letters
• /
• v.11 no.3
• /
• pp.275-279
• /
• 2005

High-salted mineral water (Daehan Deep Water, Korea) that is pumped up from below the sedimentary rock layer of Dadaepo, Busan, Korea has a composition similar with that of deep sea water. Under the well-being boom, the mineral water is processed for various uses including washing or oral administration. However, high concentrations of various minerals in the mineral water are suspected to affect on the physiology of human body, especially on blood pressure (BP). Here, we examined the effect of Hot Mineral(R), dried powder of the mineral water, on the change of BP. Sprague­Dawley rats were grouped and orally administered $2.5\%$ Hot Mineral(R) (group M), $2.5\%$ NaCl (group S) or normal water (group C). Excreted urine was collected in metabolic cage for 24 hours. The systolic blood pressure (SBP) of the group S was remarkably increased (P<0.005) compared with that of the group M and the group C, which showed little changes of the SBP during 2 weeks. While average daily sodium intake were 0.32 mg in the group C, 6.64 mg in the group M and 4.07 mg in the group S, average daily sodium excretion were 11.37 mg, 53.70 mg and 7.75 mg, respectively. These results indicate that the sodium excretion in the group M was much higher than the other two groups. In this study, we suppose that the plenty amount of minerals such as calcium, potassium and magnesium in Hot Mineral? have an effect not to increase the SBP and to prompt sodium excretion out of the body. Therefore, these results suggest that oral administration of appropriate amount of Hot Mineral(R) for limited period does not induce increased SBP.

• The Korean Journal of Quaternary Research
• /
• v.23 no.2
• /
• pp.48-55
• /
• 2009

To investigate the paleoceanographic environmental changes around the Okinawa Trough, Japan, a piston core (RN88-PC5) was conducted on benthic foraminiferal species composition, assemblage, sedimentological and geochemical analyses. Trubidite sediment intercalated in studied core contains different benthic foraminiferal species, dwelling in shallow coral reef species, from normal hemipelagic sediment. These different benthic foraminiferal species and its assemblage are interpreted as reworked sediment when turbidite current occurred, synchronically. Grain size analysis clearly showed that mean grain size difference occurred between trubidite and hemipelagic sediments. Geochemical analysis also showed the difference of chemical composition between two sedimentary facies. Results of the foraminiferal oxygen isotope analysis showing global surface water warming records since the last 10 ka. The geochemcial analysis and previous works showed that turbidite sediment of studied core indicating sporadic occurrence of regional paleoceanographic events. Assemblage of shallow coral reef benthic foraminifera especially occurred with turbidite layer clearly support the sporadic occurrence of paleoceanographic events such as regional earthquake.

• The Korean Journal of Quaternary Research
• /
• v.23 no.2
• /
• pp.34-47
• /
• 2009

AMS radiocarbon dates indicated that Eurimji reservoir, located at Jecheon City, Chungbuk Province, has been formed during the late Holocene Epoch. The sedimentary sequence at bottom reveals histories in hydrology, climate conditions and past vegetation dynamics. Ages controlled sedimentological and palynological analyses on ER 3-1 Core contribute to reconstruct paleoclimate and past hydrological conditions. These analyses suggest that lower interval (307.5m~309.5m elevations) of the ER 3-1 Core was deposited in stable from 1,920 yrBP to 1,420 yrBP, but upper layer sediment above these elevations was composed of reworked sediments during the pre and post 2,000 yrBP. Pollen assemblage indicates that watershed vegetation of the Eurimji reservoir, during the period of 1,920 yrBP~1,420 yrBP, was closely comparable to modern vegetation dominated Pinus and Quercus mixed vegetation. Also, riparian including Alnus, Fraxinus and Salix were inhabited along the banks of stream, and aquatics such as Typha, Nymphaea and Persicaria flourished at shore of the reservoir. According to cultural chronicle, it infers that the Eurimji reservoir was formed from the Bronze Age to the Iron Age or the beginning of ancient society. An integrated data suggested that Quercus-Pinus-Abies mixed forest flourished under cool and dry climate conditions during 3,200 yrBP~200 yrBP.

• Geophysics and Geophysical Exploration
• /
• v.20 no.2
• /
• pp.88-95
• /
• 2017

Chogye basin, which is surrounded by country rock, has a closed-basin form. In such a basin, incident seismic energy can form multiply reflected waves, thus causing energy concentration to occur at this closed-basin area. Microtremor measurement survey was performed at the Chogye basin, which is located in Chogye-myeon and Jeokjungmyeon, Hapcheon-gun, Gyeongsangnam-do, Republic of Korea. Microtremor data were transformed into the frequency domain, and then the horizontal-to-vertical spectral ratios (HVSR) were calculated. Fundamental resonance frequencies were estimated from the HVSR results for every observation point. Using the empirical relationship between site period and thickness for sediment sites in Korea known from the previous study, the distribution of sediment thickness of the Chogye basin was estimated from the fundamental resonance frequencies. Being compared with the mountainous rim with steep slope, the measurement points inside the basin have low values of the fundamental resonance frequency with the minimum of 1.03 Hz, which corresponds to the thickness of sedimentary layer with the maximum depth of about 100 m. A three-dimensional basin model was constructed for bedrock topography of the Chogye basin by an interpolation of basin depths estimated at each measurement site.

• Journal of Conservation Science
• /
• v.33 no.1
• /
• pp.1-10
• /
• 2017

The rock-carved seated Buddha of Unju temple of Hwasun, Jeonnam, the only Triad Buddha among the stone Buddhas of Unju temple, is currently designated as a tangible cultural property No. 275 of Jeollanam-do. The rock of the seated Triad Buddha bedrock is light-green andesitic tuff breccia that is composed of quartz and feldspar. The results of measurement of the whole rock magnetic susceptibility characteristics, the rock consists of a single sedimentary layer from top to bottom. The results of ultrasonic velocity measurement, show that the number of frequency of 1500~2000 m/s increased and the number of frequency of 2000~2500 m/s decreased in 2009 compared to 2015, and the measurement value for 2000 m/s or below was 87.5% in 2015, a 68.8% increase in comparison to that in 2009. Moreover, on the top, bottom, left side, and head areas of the Triad Buddha, a partial expanding tendency was observed in the range of low ultrasonic velocity. As weathering of the Triad Buddha occurs in the long term, on-going monitoring is required to ascertain the degree of change with time.

• The Journal of Engineering Geology
• /
• v.12 no.4
• /
• pp.471-484
• /
• 2002

Alluviums in the Keum River watershed cover an areal extent of $3,029{\;}\textrm{km}^2$ and contain about 8.1 billion tons of groundwater. However, the waters are severely polluted by nitrate, possibly due to the application of nitrogen fertilizer (>250 N kg/ha) on agricultural land. This paper aims to elucidate the pollution status and behaviors of nitrate in alluvial groundwaters in the Keum River watershed area, based on regional hydrogeochemical study. Most of the collected samples (n = 186) are polluted by nitrate (average = 42.2 mg/L, maximum = 295 mg/L). About 29% of the samples have the nitrate concentrations exceeding Korean Drinking Water Standard (44 mg/L $NO_3$). The distribution of nitrate concentrations in the study area is largely dependant on geochemical environments of alluvial aquifers. In particular, the decrease of redox potential of alluvial groundwaters showed a good correlation with the decreases of nitrate, iron, and manganese concentrations. Thus, the change of redox state in alluvial aquifers, likely reflecting their sedimentary environments, controls both the behavior and fate of nitrogen compounds and their natural attenuation (denitrification) in aquifers. A carbon-rich, silty layer within alluvium strata forms a reducing condition and possesses a buffering capacity on nitrate pollution.

• Economic and Environmental Geology
• /
• v.31 no.3
• /
• pp.235-247
• /
• 1998

A new technique of simultaneons inversion for 3-D seismic velocity structure by using direct, reflected, and refracted waves is applied to the center of the Korean Peninsula including Pyongnam Basin, Kyonggi Massif, Okchon Fold Zone, Taebaeksan Fold Zone, Ryongnam Massif and Kyongsang Basin. Pg, Sg, PmP, SmS, Pn, and Sn arrival times of 32 events with 404 seismic rays are inverted for locations and crustal structure. 5 ($1^{\circ}$ along the latitude)${\times}6$ ($0.5^{\circ}$ along the longitude) ${\times}8$ block (4 km each layer) model was inverted. 3-D seismic crustal velocity tomography including eight sections from the surface to the Moho, eight profiles along latitude and longitude and the Moho depth distribution was determined. The results are as follows: (1) the average velocity and thickness of sediment are 5.15 km/sec and 3-4 km, and the velocity of basement is 6.12 km/sec. (2) the velocities fluctuate strongly in the upper crust, and the velocity distribution of the lower crust under Conrad appears basically horizontal. (3) the average depth of Moho is 29.8 km and velocity is 7.97 km/sec. (4) from the sedimentary depth and velocity, basement thickness and velocity, form of the upper crust, the Moho depth and form of the remarkable crustal velocity differences among Pyongnam Basin, Kyonggi Massif, Okchon Zone, Ryongnam Massif and Kyongsang Basin can be found. (5) The different crustal features of ocean and continent crust are obvious. (6) Some deep index of the Chugaryong Rift Zone can be located from the cross section profiles. (7) We note that there are big anisotropy bodies near north of Seoul and Hongsung in the upper crust, implying that they may be related to the Chugaryong Rift Zone and deep fault systems.