• The Journal of Engineering Geology
• /
• v.10 no.2
• /
• pp.215-233
• /
• 2000

The national geochemical baseline mapping project has been conducted since 1996 to establish a quantitative assessment system for geochemical hazards in natural environments. The geochemical image maps have been edited for thirty-six elements(i.e., 10 major oxides and 26 trace elements) in light sediments, finer fraction than 150 $\mu$m, collected from first- to second-order streams(totally 11,000) over five provinces in the western half(ca. 45,000 km$^2$) of Korea. Natural background values of the elements were given for different geological environments. Based on the statistics, geochemical baselines were newly obtained for a quantitative hazard assessment on toxicity of heavy metals and deficiency of essential nutrients. Some chosen examples of geochemical hazards are presented based on new geochemical image maps and related baseline data.

• Nuclear Engineering and Technology
• /
• v.33 no.3
• /
• pp.261-269
• /
• 2001

In this study, sorption experiments of uranium onto silica colloids were carried out and the effects of important geochemical parameters such as pH, ionic strength, carbonate concentration, colloid concentration, and total concentration of uranium were investigated. The sorption coefficients of uranium for silica colloids named as pseudo-colloid formation constants were about 10$^4$~ 10$^{5}$ mL/g depending on the experimental conditions. The effects of the geochemical parameters were found to be important in the sorption of uranium onto silica colloids. A Langmuir type sorption isotherm of uranium between silica colloids and the solution phase was also presented. The sorption mechanisms were explained by analyzing the effects of the geochemical parameters.

• Economic and Environmental Geology
• /
• v.13 no.4
• /
• pp.241-246
• /
• 1980

Some components in uranium-bearing formations which consist mainly of black shale, slate. and low grade coal-bearing formation of Ogcheon Belt were processed statistically in order to find out the geochemical correlations with uranium. Geochemical enrichment of uranium, vanadium and molybdenum in low grade coal-bearing formations and surrounding rocks is remarkable in the studied area. Geochemical correlation coefficient of uranium and molybdenum in the rocks displays about 0.6, and that of uranium and fixed carbon about 0.4. Uranium and vanadium in uranium-bearing low grade coals denote very high correlation with fixed carbon, which is considered to be responsible for enrichment of metallic elements, especially molybdenum. Close geochemical correlation of uranium-molybdenum couple in the rocks can be applied as a competent exploration guide to low grade uranium deposits of this area.

• Geophysics and Geophysical Exploration
• /
• v.10 no.1
• /
• pp.37-43
• /
• 2007

The MH21 Research Consortium has conducted a high-resolution 3D seismic survey and a seafloor geochemical survey, to explore methane hydrate reservoirs in the eastern Nankai Trough, offshore Japan. Excellent geological information about shallow formations was obtained from the high-resolution 3D seismic survey, which was designed to image the shallow formations where methane hydrates exist. The information is useful in constructing a geological and geochemical model, and especially to understand the complex geology of seafloor, including geochemical manifestations and the structure of migration conduits for methane gas or methane-bearing fluid. By comparing methane seep sites observed by submersibles with seismic sections, some significant relationships between methane hydrate reservoirs, free gas accumulations below the seafloor, and seafloor manifestations are recognised. Bathymetric charts and seafloor reflection amplitude maps, constructed from seismic reflections from the seafloor, are also useful in understanding the relationships over a vast area. A new geochemical seafloor survey targeted by these maps is required. The relationships between methane hydrate reservoirs and seafloor manifestations are becoming clearer from interpretation of high-resolution 3D seismic data. The MH21 Research Consortium will continue to conduct seafloor geochemical surveys based on the geological and geochemical model constructed from high-resolution 3D seismic data analysis. In this paper, we introduce a basis for exploration of methane hydrate reservoirs in Japan by fusion of 3D seismic exploration and seafloor geochemical surveys.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.97-99
• /
• 2004

To understand the geochemical processes controlling the distribution of nitrate and other agricultural constituents in an alluvial aquifer, hydrogeological and hydro geochemical studies were carried out in an agricultural area within Cheonan. In this selected field, nitrate concentrations were very wide in range but was locally attenuated significantly down to very low levels (<1.0 mg/L). Abrupt removal of nitrate coincided with the pattern of redox change and thus indicated that geochemical processes occurring during and after recharge events control the behavior and distribution of nitrate and other redox-sensitive chemical species.

• Economic and Environmental Geology
• /
• v.39 no.1 s.176
• /
• pp.53-61
• /
• 2006

Geochemical and sedimentological analyses of sediment piston core were used to trace paleoceanographic environmental changes in the East China Sea. The analytical results revealed three lithostratigraphic units (I, II, and III) corresponding to a highstand stage, a transgressive stage, and a lowstand stage, respectively. Accelerator mass spectrometry (AMS) $^{14}C$ dated the boundaries between the units as 7 ka and II ka. That is, Unit I extended from the present to 7 ka, Unit II occupied a transitional episode from 7 to 11 ka, and Unit III was older than 11 ka. The transitional episode was characterized by sudden fluctuations in various geochemical proxies. Most strikingly, there was a gradual upward increase in both carbonate and total organic carbon (TOe) contents post-7 ka, during which time the ${\delta}^{l3}C$ values of organic material increased to a constant value. The gradual upward increase in the TOC and $CaCO_3$ contents in Unit I were accompanied by slight variations in grain size that probably reflect a stable modern oceanographic environment. Within Unit II (7 to 11 ka), the geochemical signals were characterized by abrupt and steep fluctuations, typical of a transgressive stage. Vertical mixing may have provoked an increase in productivity during this interval, with large amounts of terrigenous organic matter and/or freshwater being supplied by neighboring rivers. The geochemical signals remained stable throughout Unit III but exhibited different patterns than signals in Unit I. The high terrigenous organic matter content of Unit III suggests correspondence to a lowstand stage.

• Economic and Environmental Geology
• /
• v.38 no.6 s.175
• /
• pp.663-673
• /
• 2005

This study investigates the relationship between the geochemical maps and the gold-silver deposit locations. Geochemical maps of 21 elements, which are published by KIGAM, locations of gold-silver deposits, and 1:1,000,000 scale geological map of Korea are utilized far this investigation. Pixel size of the basic geochemical maps is 250m and these data are resampled in 1km spacing for the statistical analyses. Relationship between the mine location and the geochemical data are investigated using bayesian statistics and decision tree algorithms. For the bayesian statistics, each geochemical maps are reclassified by percentile divisions which divides the data by 5, 25, 50, 75, 95, and $100\%$ data groups. Number of mine locations in these divisions are counted and the probabilities are calculated. Posterior probabilities of each pixel are calculated using the probability of 21 geochemical maps and the geological map. A prediction map of the mining locations is made by plotting the posterior probability. The input parameters for the decision tree construction are 21 geochemical elements and lithology, and the output parameters are 5 types of mines (Ag/Au, Cu, Fe, Pb/Zn, W) and absence of the mine. The locations for the absence of the mine are selected by resampling the overall area by 1 km spacing and eliminating my resampled points, which is in 750m distance from mine locations. A prediction map of each mine area is produced by applying the decision tree to every pixels. The prediction by Bayesian method is slightly better than the decision tree. However both prediction maps show reasonable match with the input mine locations. We interpret that such match indicate the rules produced by both methods are reasonable and therefore the geochemical data has strong relations with the mine locations. This implies that the geochemical rules could be used as background values oi mine locations, therefore could be used for evaluation of mine contamination. Bayesian statistics indicated that the probability of Au/Ag deposit increases as CaO, Cu, MgO, MnO, Pb and Li increases, and Zr decreases.

• Journal of the Speleological Society of Korea
• /
• v.24 no.25
• /
• pp.1-14
• /
• 1991

Jeongsun limestone formations with good geochemical solution of limestone and physical environments have been developing many Karst landforms. Especially, there are many dolines and most of them elliptical shapes of planes. At present, they have been transformed into uvala toward their long diameter directions. The period of landscape processing is a Quaternary Epoch and Karst cycle corresponds to a stage from late maturity to old stage.

• Economic and Environmental Geology
• /
• v.35 no.2
• /
• pp.137-147
• /
• 2002

Natural geological and environmental processes reflect to element abundances in geological materials on the surface. This study aims to elucidate a possibility of geostatistical application to differentiate geochemical anomalies affected by anthropogenic and geogenic factors. A regional geochemical map was produced using 'inverse distance weight interpolation' method for analytical results of stream sediments «150 11m) which were collected from 2,290 first- to second-order streams over the whole Gyeonggi Province. The Jurassic granitic batholith in the southeastern province was selected as a target for the geostatistical examination. Factor analysis was conducted using 22 elements for stream sediments from 445 drainage basins over the granitic body. Co, Cr, Sc, MgO, Fe$_{2}$O$_{3}$, V, and Ni were grouped with high correlation coefficients and the depletion of the components may reflect the whole-rock chemistry of the granite. Regression analysis was done using Co, Cr, and Sc as dependent variables and other six components as independent variables, and the results were drawn as maps. The maps acquired generally show quite similar distribution patterns with those of concentrations of each variable. The similarity in the spatial patterns between the two maps indicates that the application of regression statistics can be valid for the interpretation of regional geochemical data. However, some components show local discrepancies which may be influenced by secondary factors regardless of the basement lithology. The regression analysis may be effective in extracting local geochemical anomalies which may reflect rather anthropogenic pollutions than geogenic influences.

• Economic and Environmental Geology
• /
• v.44 no.3
• /
• pp.203-215
• /
• 2011

Geochemical and mineralogical properties of a contamited soil should be taken into account to decide a remediation strategy for a given contaminant because development and optimization of soil remedial technologies are based on geochemical and mineralogical separation techniques. The objective of this study was to investigate the geochemical and mineralogical characteristics of arsenic-contaminated soils. The arsenic-contaminated soil samples were obtained from Chonam gold mine, Gwangyang, Chonnam, Particle size analysis, sequential extraction, and mineralogical analyses were used to characterize geochemical and mineralogical characteristics of the As-contaminated soils. Particle size analyses of the As-contaminated soils showed the soils contained 17-36% sand, 25-54% silt, 9-28% clay and the soil texture were sandy loam, loam, and silt loam. The soil pH ranged from 4.5 to 6.6. The amount of arsenic concentrations from the sequential soil leaching is mainly associated with iron oxides (1 to 75%) and residuals (12 to 91%). Major minerals of sand and silt fractions in the soils were feldspar, kaolinite, mica, and quartz and minor mineral of which is an iron oxide. Major minerals of clay fraction were composed of illite, kaolinite, quartz, and vermiculite. And minor minerals are iron oxide and rutile. The geochemical and mineralogical analyses indicated the arsenic is adsorbed or coprecipitated with iron oxides or phyllosilicate minerals. The results may provide understanding of geochemical and mineralogical characteristics for the site remediation of arsenic-contaminated soils.