• Economic and Environmental Geology
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• v.18 no.4
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• pp.399-410
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• 1985

Bentonites from the Janggi Group of the Lower Miocene age from the Geumgwangdong area, Korea, have been studied for mineralogical and genetic characterization. The Janggi Group is subdivided, in ascending order, into the Janggi Conglomerate, the Nuldaeri Tuff, the Geumgwangdong Shale, the Lower Coal-bearing Formation, the Basaltic Tuff, and the Upper Coalbearing Formation. Bentonites occur as thin or thick beds in all sedimentary units of the Janggi Group, except for the Janggi Conglomerate. Significant bentonite deposits are found in the Nuldaeri Tuff, the Lower Coal-bearing Formation and the Basaltic Tuff. Bentonites consist mainly of smectite (mainly montmorillonite), with minor quartz, cristobalite, opal-CT and feldspar. Occasionally, kaolinite, clinoptilolite or gypsum is associated with bentonites. Bentonites were studied by the methods of petrographic microscopy, X-ray diffraction, thermal analysis (DT A and TG), infrared absorption spectroscopic analysis, SEM, intercalation reaction, and chemical analysis. Smectites commonly occur as irregular boxwork-like masses with characteristic curled thin edges, but occasionally as smoothly curved to nearly flat thin flakes. Most of smectites have layer charge of 0.25-0.42, indicating typical montmorillonite. Crystal-chemical relations suggest that Fe is the dominant substituent for Al in the octahedral layer and there are generally no significant substituents for Si in the tetrahedral layer. Ca is the dominant interlayer cation in montmorillonite. Therefore, montmorillonite from the study area is dioctahedral Ca-montmorillonite. Occurrence and fabrics of bentonites suggest that smectites as well as cristobalite, opal-CT and zeolites have been formed diagenetically from tuffaceous materials. The precursor of smectites is trachytic or basaltic tuff. Smectites derived from the former contain relatively more $Al_2O$ a and less $Fe_2O_3$ than those from the latter.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.39-45
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• 1987

A water culture experiment was conducted to investigate the effect of As content in a culture solution on the water status and growth of rice plants. Rice (Oryza sativa L. Line. Iri 316) seeds were germinated in bentonite and cultivated there for 30 days. Rice seedlings were transplanted into 3.5l pots containing the culture solution on May 1, 1985 and allowed to grow without As treatment for one month. Afterwards, they were grown in a culture solution maintaining the final concentration of As, 0, 1, 5, 10 and 15mg/1 renewing in the solution dissolved sodium arsenate at intervals of 3 to 7 days. Plants were cultivated in the green house during the growing period and harvested 60 days after As treatment. The results obtained were as follows: Transpiration of rice plants was decreased with the increase of the As level in the culture solution. Stomatal diffusive resistance and leaf temperature increased with increase of As levels though the humidity and the air flow rate in leaf decreased. Air flow rate, transpiration and stomatal diffusive resistance showed a highly significant correlation with As contents in shoots and roots of rice plants: Espally The air flow rate and transpiration revealed a significantly higher correlation with As contents in the root than that in the shoot, but diffusive resistance showed adverse tendency. High levels of As in the culture solution depressed plant height, no. of tillers, leaf width and dry weight of plant remarkably. Typical symptoms of As toxicity were root discoloration, and necrosis of leaf tips and margins, and leaf rolling during the sunny daytime were also another symptoms.

• Journal of the Korean GEO-environmental Society
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• v.22 no.6
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• pp.17-26
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• 2021

Ground investigation and result analysis generally used to examine all sorts of structures' subsidence or stability can be classified into sandy soil and cohesive soil, and analysis on the liquid limit of soil is utilized to evaluate the physical properties of ground and types or technical behavior of soil. The most widely used method to analyze liquid limit is Casagrande with which liquid limit can be calculated relatively easily; however, it is fairly difficult to apply it to soil equipped with intermediate properties. Therefore, concerning the properties of soil having the intermediate properties of sedimentary ground, this researcher mixed the clay from Yangsan, Gwangyang, and Busan with sandy soil to make intermediate soil and then carried out the test of consistency limit and also evaluated applicability by using the suggested formula of consistency revision. The sample of intermediate soil was the mixture of clay and sandy soil, and to produce intermediate soil, the content (F_c) of fine soil was applied as 50%, 75%, or 100%. Regarding the physical properties of intermediate soil, to maintain the properties of clay in the natural state, bentonite was added at a fixed rate for controlling the properties of clay, and then, consistency was analyzed. By adopting the formula of consistency revision suggested in advanced research, this author analyzed consistency based on the experiment and consistency based on the suggested formula of revision. Also, about intermediate soil collected at the site, consistency based on the experiment and consistency based on the suggested formula of revision were analyzed comparatively, and about intermediate soil collected, this researcher analyzed particle size and calculated the content (F_c) of fine soil to analyze intermediate soil in diverse conditions. Moreover, about intermediate soil collected at the site, the suggested formula of consistency revision was applied to calculate the compression index, and the compression index based on the experiment and the compression index based on the suggested formula were analyzed comparatively to evaluate the applicability of the suggested formula.

• Economic and Environmental Geology
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• v.56 no.2
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• pp.167-183
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• 2023

Gases originated from the final SNF (spent nuclear fuel) disposal site are very mobile in the barrier and they may also affect the migration of radioactive nuclides generated from the SNF. Mechanisms of gas-nuclide migration in the multi-barrier and their influences on the safety of the disposal site should be understood before the construction of the final SNF disposal site. However, researches related to gas-nuclide coupled movement in the multi-barrier medium have been very little both at home and abroad. In this study, properties of gas generation and migration in the SNF disposal environment were reviewed through previous researches and their main mechanisms were summarized on the hydrogeological evolution stage of the SNF disposal site. Gas generation in the SNF disposal site was categorized into five origins such as the continuous nuclear fission of the SNS, the Cu-canister corrosion, the oxidation-reduction reaction, the microbial activity, and the inflow from the natural barriers. Migration scenarios of gas in porous medium of the multi-barrier in the SNF repository site were investigated through reviews for previous studies and several gas migration types including ① the free gas phase flow including visco-capillary two-phase flow, ② the advection and diffusion of dissolved gas in pore water, ③ dilatant two-phase flow, and ④ tensile fracture flow, were presented. Reviewed results in this study can support information to design the further research for the gas-nuclide migration in the repository site and to evaluate the safety of the Korean SNF disposal site in view points of gas migration in the multi-barrier.