• Economic and Environmental Geology
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• v.18 no.2
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• pp.107-124
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• 1985

More than fifty copper veins are emplaced around late Cretaceous granitoid stock in Haman-Gunbuk district, southernmost part of Korea. These veins cut both late Cretaceous granitoids and hornfels of Jindong formation which is intruded by the granitoids. The paragenesis of veins is nearly the same, consisting of (1) an early vein stage in which most iron oxide minerals, tourmaline and other silitcate minerals were deposited, (2) a calcite and quartz with base·metal sulfide stage and (3) late vein lets of barren calcite stage. Fluid inclusion studies reveal highly systematic trends of salinity and temperature during mineralization. Ore fluids of early vein stage were complex NaCl-KCl rich brines. Salinities of polyphase inclusions in quartz and scapolite in thie stage reached up to 72 wt.% and gradually decreased to 10.5wt. % in closing stage. Homogenization temperatures of inclusions in the beginning of this stage were up to $490^{\circ}C$ and then declined steadly to $290^{\circ}C$ in the late stage. Salinities of fluid inclusions in quartz and calcite of base·metal sulfide stage were 37.4~5.7wt. % and homogenization temperatures range from $373^{\circ}C$ to $170^{\circ}C$. Intermittent boiling of early vein fluid is indicated by fluid inclusions in quartz. Potassic alteration of granodiorite adjacent to early vein seems to be related to early saline vein fluid. Fluid inclusion data of base-metal sulfide stage of this area reveal nearly the same range as those of Koseong copper mining district about 30km apart from this area.

• Economic and Environmental Geology
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• v.43 no.6
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• pp.543-553
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• 2010

This study was focused on the mineralogical and geochemical characteristics of field soil of the Baekje Kingdom from K wongbawigol site in Jeongdongri, Buyeo and whether the bricks from Songsanri Tombs and Muryung's Royal Tomb were made of soil from this site. Soil samples show the similar size fraction as a silt loam and acidic soil, whereas some samples have the enrichment of organic matter, P and S. Also, they have similar geochemical behavior of elements and similar mineral phases consisting of quartz, plagioclase, orthoclase, vermiculite, mica and kaolinite. The enrichment of iron oxide is found in some soil layer, including the iron oxide mottling and precipitation along plant roots and they are attributed to repeat oxidation and reduction environments due to flooding and drainage of field soil. It's anthropogenic alteration by human activity. Especially, it is assumed that the concentration of the iron oxides found in bricks from Muryung's Royal Tomb and Songsanri Tombs is the additional evidence that soil in this study is probably the raw materials of those bricks.

• Journal of the Mineralogical Society of Korea
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• v.23 no.1
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• pp.39-50
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• 2010

Zeolites were formed by the alteration of volcanic glass in the volcaniclastics including tuff cone/rings and subsurface Seoguipo Formation, Jeju Island. Phillipsite and analcime were identified by X-ray diffraction and electron microprobe analysis. Si/(Si+Al) atom ratios of analcime and phillipsite were similar to that of parent basaltic glass. In comparison with the simple chemistry of analcime, phillipsite showed a range of cavity cation compositions. Na is the major cavity cations of phillipsite in the Dangsanbong and Yongmeori tuffs bearing analcime, while K and Ca in core samples of Seoguipo Formation. Microtextural analysis by scanning electron microscope showed a general sequence that early phillipsite encrustification of pores was followed by later analcime infilling. Zeolites are abundant in the older tuff cone/rings but nearly absent in the younger ones.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.347-354
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• 2004

We report the petrographic and petrochemical results on the rocks which have been classified as hornfelsic sandstones or mudstones of the Gyeongsang Group in Wolseong Area, part of Choyang Geologic Sheet (Tateiwa, 1924) and discuss its origin. The rocks consist of alternating layers with dark. fine-grained and bright, coarse-grained but don't have any clues of thermal alteration such as hornfels. The rocks are composed of quartz, feldspar and rock fragments of volcanic origin. The overall geochemical characteristics of the rocks indicate that the rocks have mainly rhyolitic composition with 64.5-72 wt% SiO$_2$ and are similar to the trend of Cretaceous and Tertiary volcanic rocks around this area. On the contrary, the geochemical characteristics of rocks are distinguished from those of Lower Cretaceous Sindong and Mayans mudrocks in the Gyeongsang Basin. We re-name the rocks as rhyolitic tuffite.

• Economic and Environmental Geology
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• v.57 no.3
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• pp.293-303
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• 2024

River mining, the extraction of sand and gravel from riverbeds, is rising at an alarming rate to keep pace with the increasing demand for construction materials worldwide. The far-reaching deleterious effects of river mining include the lowering of water levels, the augmentation of turbidity, and the erosion of riverbanks, i.e., the disruption of water flow and alteration of river morphology. Aggregates demand, geolocation, and the economy of Bangladesh accelerated illegal extraction. However, limited research has been carried out in this region, despite the severe impact on aquatic and terrestrial ecosystems. To address the corresponding consequences and direct the scope for further research, it is required to evaluate existing studies of other countries having similarities in river morphology, climate, economy, and other related parameters. In this respect, based on previous studies, the effects of sand extraction are particularly prominent in India, having 54 cross-boundary rivers with Bangladesh. The geological profile of numerous rivers in the past decades has been altered due to natural aggregate mining in the Indian subcontinent. Hence, this study focused on relevant research in this region. However, the existing research only focuses on the regional portion of the aforementioned international rivers, which lacks proper assessments of these rivers, taking into account especially the mining effects. Moreover, several global rivers that have similarities with Bangladeshi rivers, considering different parameters, are also included in this study. The findings of this article underline the pressing need for more efficacious measures to address the adverse effects of river mining and safeguard ecosystems and communities globally, especially in the Indian subcontinent, where the situation is particularly vulnerable. For this reason, targeting the aforementioned region, this review highlights the global evidence in assessing the future effects of river mining and the need for further research in this field.

• Economic and Environmental Geology
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• v.37 no.1
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• pp.1-19
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• 2004

Metallic deposits in Korea have a variety of genetic types such as hydrothermal veins, skarns, hydrothermal replacement and alaskite deposits and so on. Geological, mineralogical and geochemical features including host rock, wall-rock alteration, ore and gangue mineralogy, mineral texture and secondary mineralogy related to weathering process control the environmental signatures of mining areas. The environmental signatures of metallic deposits closed from early 1970s to late 1990s in Korea show complicate geochemistry and mineralogy due to step weathering of primary and secondary minerals such as oxidation-precipitation-remobilization. The potentiality of low pH and high heavy metal Concentration s from acid mine drainage is great in base-metal deposits associated with polymetallic mineralization, breccia-pipe type and Cretaceous hydrothermal Au veins with the amount of pyrite whereas skam, hydrothermal replacement, hydrothermal Cu and Au-Ag vein deposits are in low contamination possibility. The geoenvironmental models reflecting the various geologic features closely relate to disuibution of sulfides and carbonates and their ratios and finally effect on characteristics of environmental signatures such as heavy metal species and their concentrations in acid mine drainage.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.288-302
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• 2017

Accurate measurement of benthic nutrient fluxes (BNF) is a prerequisite for evaluating the effect of sediments on nutrient cycle in the surface water. The intact sediment cores were collected in July 2015 at the midstream of Nakdong River. We identified pre-incubation time (6, 12, 24 hr), dissolved oxygen concentration (90, 70, 50% saturation), diffusive boundary layer thickness (0, 0.6-0.8, 1.2-1.4 mm), and incubation temperature (10, 17, 20, $25^{\circ}C$) as the most important control factors, and measured the BNF fluctuation with the variation of these factors using the laboratory sediment core incubation method. Since the chemical composition, redox condition, hydrodynamic regimes and microbial activities at the sediment-water interface were changed as a result of the alteration of control factors, sediment core incubation should be conducted under as close to the natural conditions of study site as possible, in order to produce the results similar to actual values. Relative percentage differences between two replicates were below 20% in most control factors, which showed satisfactory precision for strict compliance with the experimental conditions and procedures. In the further studies, we will compare the results of core incubation with those of in situ measurements to confirm the accuracy of the sediment core incubation method.

• Toxicological Research
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• v.18 no.4
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• pp.355-362
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• 2002

Pathophysiological elevation of intracellular calcium concentration ($[Ca^{2+}]_1$) in the neuron has been considered as an important responsible factor in the neuronal cell damages. However the mechanism of increase of $[Ca^{2+}]_1$ and the relationship between $[Ca^{2+}]_1$ level and cytotocixity have not been fully demonstrated. In the present study, real-time alteration of $[Ca^{2+}]_1$and cellular response (cell damages) in the pheochromocytoma cells (PC12) stimulated by glutamate were investigated. Glutamate dose dependently decreased cell viability determined propidium iodide fluorescence method and morphology change. Conversely related with cell damages, glutamate dose dependently increased the level of［Ca$^{2+}$］$_{i}$ . To investigate the mechanism of glutamate-induced increase of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$, was first measured in the cell cultured in calcium free media and in the presence of dantrolene, an inhibitor of calcium release from ryanodine receptor located in endoplasmic reticulum (ER). Similar to the increase$[Ca^{2+}]_1$ in the calcium-containing media, glutamate dose dependently increased $[Ca^{2+}]_1$ in the cell cultured in free calcium media. However pretreatment (2 hr) with 20~50 $\mu\textrm{M}$ dantrolene substantial lowered glutamate-induced increase of $[Ca^{2+}]_1$, suggesting that release of calcium from ER may be major sourse of increase of $[Ca^{2+}]_1$ in PC12 cells. Dantrolene-induced inhibition of $[Ca^{2+}]_1$ resulted in recovery of cytotoxicity by glutamate. Relevance of N-methy-D-aspartate (NMDA) receptor, a type of glutamte receptor on glutamate-induced incense of $[Ca^{2+}]_1$,$[Ca^{2+}]_1$ was also determined in the cells pretreated (2 hr) with NMDA receptor antagonist MK-80l. Glutamate-induced increase of $[Ca^{2+}]_1$ was reduced by MK-801 dose dependently. Furthermore, glutamate-induced cytotoxicity was also prevented by MK-80l. These results demonstrate that glutamte increase $[Ca^{2+}]_1$ dose dependently and thereby cause cytotoxicity. The increase of $[Ca^{2+}]_1$ may release from ER, especially through ryanodine receptor and/or through NMDA receptor Alteration of calcium homeostasis through disturbance of ER system and/or calcium influx through NMDA receptor could contribute glutamate-induced cell damages.s.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.9 no.2
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• pp.66-78
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• 1999

The purpose of this study was to investigate the toxic effects of iso-butylalcohol on Sprague-Dawley (SD) rats which were treated 0, 333, 1,000 and 3,000 ppm for 6 hours a day, 5 days a week for 13 weeks by inhalation. Iso-butylalcohol did not induce any abnormal change in the viewpoint of clinical signs, feed consumption, ophthalmic test, urinalysis, hematology and blood biochemistry during and at the termination of the inhalation toxicity test. We did not find any abnormal findings in the gross and microscopic observations due to the inhalation of iso-butylalcohol. There was no alteration in relative organ weight owing to the inhalation of the iso-butylalcohol. In conclusion, concentration was 3,000 ppm in rats under the inhalation of 6 hours a day, 5 days a week for 13 week. Iso-butylalcohol did not show any change in the clinical signs, feed consumption, ophthalmic test, urinalysis, hematology and blood biochemistry, together with no alteration in the gross and pathological findings.

• Journal of Ginseng Research
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• v.47 no.4
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• pp.561-571
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• 2023

Background: Escalating evidence shows that ginseng possesses an antiaging potential with cognitive enhancing activity. As mountain cultivated ginseng (MCG) is cultivated without agricultural chemicals, MCG has emerged as a popular herb medicine. However, little is known about the MCG-mediated pharmacological mechanism on brain aging. Methods: As we demonstrated that glutathione peroxidase (GPx) is important for enhancing memory function in the animal model of aging, we investigated the role of MCG as a GPx inducer using GPx-1 (a major type of GPx) knockout (KO) mice. We assessed whether MCG modulates redox and cholinergic parameters, and memory function in aged GPx-1 knockout KOmice. Results: Redox burden of aged GPx-1 KO mice was more evident than that of aged wild-type (WT) mice. Alteration of Nrf2 DNA binding activity appeared to be more evident than that of NFκB DNA binding activity in aged GPx-1 KO mice. Alteration in choline acetyltransferase (ChAT) activity was more evident than that in acetylcholine esterase activity. MCG significantly attenuated reductions in Nrf2 system and ChAT level. MCG significantly enhanced the co-localization of Nrf2-immunoreactivity and ChAT-immunoreactivity in the same cell population. Nrf2 inhibitor brusatol significantly counteracted MCG-mediated up-regulation in ChAT level and ChAT inhibition (by k252a) significantly reduced ERK phosphorylation by MCG, suggesting that MCG might require signal cascade of Nrf2/ChAT/ERK to enhance cognition. Conclusion: GPx-1 depletion might be a prerequisite for cognitive impairment in aged animals. MCG-mediated cognition enhancement might be associated with the activations of Nrf2, ChAT, and ERK signaling cascade.