• Journal of Wetlands Research
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• v.21 no.2
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• pp.125-131
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• 2019

The Nakdong Estuary has experienced hydraulic and topographic changes over the last century, which have had negative effects of habitat loss and fragmentation. The population of Scirpus planiculmis, a major food plant for wintering birds in Nakdong Estuary, has decreased over the last decade. To identify factors that influence S. planiculmis population, 6 short core samples (about 30cm) were collected in June and August, 2018. The sand percentage was over 80% in every samples and the average sediment salinity in June and August were $17.8{\pm}1.12psu$ and $18.4{\pm}1.83psu$, respectively. ${\delta}^{13}C$ of sediment cores varied from -25.4‰ to -22.6‰ which fall within the estuarine particulate organic matters. In cores collected in Eulsuk area, the highest ${\delta}^{13}C$ values were observed at the surface (0~1cm) indicating inputs of marine POM (particulate organic matter) to the Nakdong Estuary. No significant difference between vegetation and non-vegetation stations was observed in every items we investigated which might indicate that the physicochemical environment of vegetation area is almost same as that of non-vegetation area. Therefore, the high sand percentage and sediment salinity of Nakdong Estuary might affect the reduction in S. planiculmis population.

• Economic and Environmental Geology
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• v.56 no.5
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• pp.581-588
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• 2023

This study reports depth-dependent elemental distribution and mineral abundance of the oceanic sediment sample (WP21GPC04) near the Mariana Trench collected during the WP21 expedition in 2021. The elemental distribution determined by μ-XRF shows no significant differences with varying depth, with an average SiO₂ 53.91 wt%, FeO 4.48 wt%, Al₂O₃ 16.56 wt%, MgO 2.56 wt%, CaO 4.79 wt%, Na₂O 3.52 wt%, K₂O 5.48 wt%, similar to the average chemical composition of global subducting sediments (GLOSS). The mineral abundances analyzed using synchrotron XRD, however, vary with depth. While quartz, mica, and plagioclase were identified at all depths, chlorite was found at shallow depths, and zeolite group minerals, phillipsite and heulandite, showed a gradual change in phase fraction with depth. This suggests a change in sedimentation and alteration environments in the region, or the potential for coexistence emerges due to similar sediment stability. Overall, this study will provide a basis for the future investigations on the evolution of sedimentary environment near the Mariana Trench in the western Pacific Ocean and the phase distribution and the behavior of subducting oceanic sediments, which will affect the lithological and geochemical characteristics of the Mariana susduction system.

• Journal of Korean Society of Forest Science
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• v.106 no.4
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• pp.424-430
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• 2017

With its rapid velocity and wide deposition, debris flow is a natural disaster that causes loss of human life and destruction of facility. To design effective debris barriers, impact force of debris flow should be first considered. Debris flow velocity is one of the key features to estimate the impact force of debris flow. In this study, we conducted small-scale flume experiments to analyze flow characteristics of debris flow, and determine flow resistance coefficients with different slope gradients and sediment mixtures. Flow velocity significantly varied with flume slope and mixture type. Debris flow depth decreased as slope increased, but difference in depth between sediment mixtures was not significant. Among flow resistance coefficients, Chezy coefficient ($C_1$) showed not only relatively highest goodness of fit, but also constant value ($20.19m^{-1/2}\;s^{-1}$) regardless the scale of debris flow events. The overall results suggested that $C_1$ can be most appropriately used to estimate flow velocity, the key factor of assessing impact force, in wide range of debris flow scale.

• Economic and Environmental Geology
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• v.44 no.1
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• pp.11-20
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• 2011

Geological survey on the occurrence of copper oxide in Suparaura area around Abancay in the south-central part of Peru had been carried out. Geology of the area is composed of granitoids such as granodiorite, tonalite and andesitic porphyry related to Tertiary igneous activity, Ferrobamba formation with Cretaceous limestone and sandstone in descending order. Red sandstone is widely distributed and emplaced with their attitude of $N70^{\circ}W$ strike and $60^{\circ}NE$ dip. Copper oxides were mineralized along the bedding plane of red sandstone with maximum width of 30 cm. Ore-body structure bounding red sandstone strata have different occurrence characteristics with generally known porphyry system in terms of alteration, mineral assemblage and occurrence mode. Therefore, it is thought to be stratiform sediment-hosted copper (SSC) deposits genetically corresponding to Mississippi-valley type from preliminary study.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.1
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• pp.107-111
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• 2012

Eight marine sediments from Busan port in Korea were annually analyzed to examine the concentration distribution of dioxins from 2006 to 2010. Yearly mean concentration of dioxins ranged from 186.3 to $383.3pg\;g^{-1}$ in real values and 5.087 to 8.541 pg-TEQ (Toxicity equivalency) based on dry weight of samples. The dioxin concentration at the site near fishing market was the highest concentration among all sampling sites. Also the dioxin concentration at the sites with various pollutant sources such as large ships, sewage influx and thermal power station as well as fishing market was higher than that of the sites without specific pollutant sources. Another main factor that affects the dioxin concentration is topography characteristics of the bay. The bay has relatively high dioxin concentration because of the lack of the pollutant diffusion. This study demonstrated that the dioxin concentration in the site with pollutant sources and the lack of the pollutant diffusion was relatively high as compared with the other sites. As a result of contribution ratio of dioxin congeners, OCDD (Octachlorodibenzodioxin) in all sites was major contributor in real value, in contrast, dioxin congeners in TEQ values were dominated by 2,3,4,7,8-PeCDF.

• Economic and Environmental Geology
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• v.47 no.2
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• pp.97-105
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• 2014

Peperite exposed along the Dajeonsa basalt in Mt.Juwang, Cheongsong emerged as a consequence of the simultaneity of volcano-sedimentary sequences. This study aims to classify peperites as morphological characteristics and infer the formation process by the field investigation, image analysis, X-Ray Diffractometer and polarization microscope for the magma-sediment interaction mechanism and paleoenvironment. As a result of the field investigation globular(fluidal) peperite is the representative feature at the bottom of Dajeonsa basalt, sub-angular peperite at the middle and irregular peperite at the top. Peperite domains range from sheet and pod or feeder conduit. Although the study that the morphologies of peperite are controled by the sorts of sediment and lava or magma has tended to center around the peperite, the study addresses not single mechanism but the multi-stage mechanism because Mt.juwang peperite, under the same conditions, varies in shapes and sizes and also the ratio of sediments that show the most change of the peperite affects to the formation of peperite.

• The Korean Journal of Food And Nutrition
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• v.33 no.3
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• pp.299-308
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• 2020

This study investigated the quality characteristics of black soybean sediments to diversify the availability of soybean. The cooking method selected for black soybean sediment preparation was a pressure cooking process without soaking, considering the isoflavone content. The black soybean sediments were prepared by the addition of 0, 10, 30, 50 and 100% (w/w) black soybean. When 0% to 100% black soybean was added to the black soybean sediments, the moisture and crude protein contents increased from 53.17% to 54.41% and from 12.07% to 21.68%, respectively. The total isoflavone content of the black soybean sediments was increased from 2.69 ㎍/g to 696.09 ㎍/g, respectively, by the addition of black soybean. The anthocyanin content of the black soybean sediments ranged from 279.29 ㎍/g to 387.8 ㎍/g by the addition of black soybean. The total polyphenol content and the total flavonoid content of the black soybean sediments range from 1.72 mg/g to 2.00 mg/g and 0.89 mg/g to 0.92 mg/g, respectively, by the addition of black soybean. Given the isoflavones, total polyphenol, and anthocyanin content of the black soybean sediments, it is appropriate that the ratio of added black soybeans is at least 50% after the pressure-cooking process, regardless of soaking.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.6
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• pp.119-124
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• 2009

In this study, the characteristics of estimating methodology for RUSLE factors such as soil erodibility factor, slope length-steepness factor, and cover management factor were reviewed and then the relative error according to each methodology was analyzed. RUSLE was applied to experimental watershed for 42 storm events and their results were compared with measured sediment yield to examine the applicability of RUSLE. As a result, this paper found that it should be necessary to consider vegetation effect for forest application of RUSLE as cover management was the most sensitive factor. Also, soil erodbility factor was calculated from data of soil series by National Academy of Agricultural Science caused sediment yield to be overestimated because there were big differences between the soil series and on-site soil texture. The 22.7% of maximum relative error was shown according to selecting the rain energy equation. In addition, it will be necessary to verify the RUSLE factors with more data in order to improve their accuracy.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.185-191
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• 1990

A study on the characteristics of phosphorus sedimentation in Nakdong Estuary Barrage was conducted in June and July, 1989. Cylindric type sediment trap was designed for collecting of downward material. Downward flux and settling velocity of downward material were $296g/m^2/d$, 1.25m/hr in mid-layer and $955g/m^2/d$, 3.31m/hr in bottom-layer, respectively Downward flux and settling velocity of phosphorus were $0.64g/m^2/d$, 0.85m/hr in mid-layer and $1.97g/m^2/d$, 1.89m/hr in bottom-layer, respectively. Fractional composition of organic phophorus in downward material was $51.9\%$ in mid-layer water and $48.3\%$ in bottom-layer water. According to the result of this study, sedimentation of phosphorus plays an important role as a sinking effect in Nakdong Estuary Barrage.

• 한국지구물리탐사학회:학술대회논문집
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• 2008.10a
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• pp.47-50
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• 2008

Streamer resistivity surveys in shallow marine environments were carried out to analyze sediment characteristics at the bottom of reservoir. Because the resistivity values of reservoir water are very low and those of sediment are relatively high, apparent resistivity values increase with depth. And it is necessary to eliminate the apparent resistivity data decreased highly when the number of separation increases. According to the repeated data processing, we proposed the resistivity ratio of upper-to-lower layer is $0.6{\sim}0.8$ because the RMS error of inversion leads to the minimum in these range. As a result of the inversion for two- and three-layer model, the inversion including water depth is proved to be more effective than conventional method.