• Economic and Environmental Geology
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• v.48 no.5
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• pp.371-377
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• 2015

Isotopic compositions of precipitation have been used to understand moisture transport in the atmosphere and interactions between precipitation and groundwater. Isotopic compositions of speleothems and ice cores, so called, ''paleoarchives'', can be utilized to interpret climate of the past and global circulation models (GCMs). The GCMs are able to explain the paleoarchives, can be validated by the precipitation isotopes. The developments of stable isotope analyzers make high-resolution isotopic studies feasible. Therefore, a high-resolution study of precipitation isotopes is needed. For this study, precipitation samples were collected for every 5 to 15 minutes, depending on precipitation rates, using an auto-sampler for precipitation isotopes near coastal area. The isotopic compositions of precipitation range from -5.7‰ (-40.1‰) to -10.8‰ (-74.3‰) for oxygen (hydrogen). The slope of ${\delta}^{18}O-{\delta}D$ diagram for the whole period is 6.8, but that of each storm is 5.1, 4.2, 7.9 and 7.7, respectively. It indicates that evaporation occurred during the first two storms, while the latter two storm did not experience any evaporation. The isotopic fractionations of precipitation has significant implications for the water cycle and high-resolution data of precipitation isotopes will be needed for the future studies.

• Proceedings of the KSEEG Conference
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• 2003.04a
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• pp.237-237
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• 2003

Preliminary studies on the seasonal variations in abundance of stable isotopes were carried out on the snow and rainwater samples from urban area. Stable isotopes and other geochemical data as a tool for characterizing the seasonality and source of pollutants were examined in study areas, especially to trace the sources of sulfate in precipitation and to distinguish sulfates of natural and anthropogenic origin. (omitted)

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.79-87
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• 1999

$^{239+240}Pu$ concentrations in precipitation were determined for the period of May 1994 to August 1996 in oder to describe current $^{239+240}Pu$ deposition at the mid-western coat of Korea (Ansan, 37$^{\circ}$17'N, $126^{\circ}$50'E). $^{239+240}Pu$ concentration in daily precipitation varied from 0.05 to 131$\mu$Bq $kg^{-1}$ with a geometric mean of $1.26\mu$Bq $kg^{-1}$. The concentration was high in the period of Yellow Sand Storm in spring and low in wet summer monsoon. The specific $^{239+240}Pu$ concentration in daily precipitation appears to be controlled by the $^{239+240}Pu$ input to the atmosphere in spring and washout effects by precipitation in the wet summer monsoon. Wet depositional flux of $^{239+240}Pu$ varied from 4 to 123$\mu$Bq $m^{-2}d^{-1}$ with a geometric mean of $33.8\mu$Bq $m^{-2}d^{-1}$ and with a maximum in the period of Yellow Sand Storm and a minimum in the period of wet summer monsoon. $^{238}Pu$/$^{239+240}Pu$ activity raios(0.04~0.31) in precipitation for March-June period suggested that one of the major sources of Pu isotopes falling in Ansan area is the arid region of the Chinese continent.

• Ocean and Polar Research
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• v.40 no.4
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• pp.289-297
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• 2018

This study reconstructs past vegetation changes in southeastern Korea over the last 30 thousand years using plant waxes (i.e. long chain n-alkanes) and their carbon isotopic compositions (${\delta}^{13}C_{alk}$) preserved in marine sediment core (KIODP 12-1) retrieved from the East Sea. Here we show changes in vegetation composition in the Korean peninsula in relation to the strength of the East Asian Summer Monsoon. During the Last Glacial Maximum (LGM), when the summer monsoon weakened, precipitation decreased and $C_3$ grassland expanded. After the LGM, the summer monsoon gradually intensified, increasing rainfall, and thus expanding the forestland coverage. Precipitation climaxed from 10 to 6 kyr BP, which includes the Holocene Climate Optimum. The grassland began to expand since 5 kyr BP due to climate warming and drying towards the present. The ${\delta}^{13}C_{alk}$ values may also have been influenced by agricultural activities, which is known to have begun since the late Neolithic (ca. 7.0~3.0 kyr BP). Our results demonstrate how changes in the global climate state influence regional atmospheric circulation and precipitation distribution, and consequently terrestrial plant composition in southeastern Korea.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.06a
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• pp.248-254
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• 2005

This paper presents a quantitative method of sequential separation of $^{90}Sr,\;^{241}Am$ and Pu nuclides with an anion exchange resin and a Sr-Spec resin. The Pu isotopes were purified with an anion exchange resin. The americium and strontium fractions were separated from the matrix elements with an oxalate co-precipitation method. Americium fraction was separated from the strontium fraction with iron co-precipitation method and purified from lanthanides with anion exchange resin. Strontium-90 was purified from other hindrance elements with the Sr-Spec resin after oxalate co-precipitation. The measurement of Pu and Am isotopes was carried out by an ${\alpha}$-spectrometer. Strontium-90 was measured by a liquid scintillation counter. The radiochemical procedure of $^{90}Sr,\;^{241}Am$ and Pu nuclides investigated in this study has been validated by application to IAEA-Reference soils.

• Analytical Science and Technology
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• v.18 no.6
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• pp.469-474
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• 2005

This paper presents a quantitative method of sequential separation of $^{90}Sr$, $^{241}Am$ and Pu radionuclides with an anion exchange resin and a Sr-Spec resin. The Pu isotopes were purified with an anion exchange resin. The americium and strontium fractions were separated from the matrix elements with an oxalate co-precipitation method. Americium fraction was separated from the strontium fraction with iron co-precipitation method and purified from lanthanides with anion exchange resin. Strontium-90 was purified from other hindrance elements with the Sr-Spec resin after oxalate co-precipitation. The measurement of Pu and Am isotopes was carried out by an ${\alpha}$-spectrometer. Strontium-90 was measured by a liquid scintillation counter. The radiochemical procedure of $^{90}Sr$, $^{241}Am$ and Pu radionuclides investigated in this study has been validated by application to IAEA-Reference soils.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.370-371
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• 2005

• Journal of Soil and Groundwater Environment
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• v.20 no.5
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• pp.34-40
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• 2015

It is reported that the intensity of rainfall will likely increase, on average, over the world on 2000. For water resources security, many studies for flow paths from rainfall or snowmelt to subsurface have been conducted. In Korea, few isotopic studies for characterizations of flow path have been undertaken. For a better understanding of how water derived from atmosphere moves to subsurface and from subsurface to stream, an analysis of precipitation and stream water using oxygen-18 and deuterium isotopes in a small watershed, Dorim-cheon, Seoul, was conducted with high resolution data. Variations of oxygen-18 in precipitation greater than 10‰ (δ¹⁸O_max = −1.21‰, δ¹⁸O_min = −11.23) were observed. Isotopic compositions of old water (groundwater) assumed as the stream water collected in advance were −8.98‰ and −61.85‰ for oxygen and hydrogen, respectively. Using a two-component mixing model, hydrograph separation of the stream water in Dorim-cheon was conducted based on weighted mean value of δ¹⁸O. As a result, except of instant dominance of rainfall, contribution of old water was dominant during the study period. On average, 71.3% of the old water and 28.7% of rainfall contributed to the stream water. The results show that even in the small watershed, which is covered with thin soil layer in granite mountain region, the stream water is considerably influenced by old water inflow rather than rainfall.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.247-247
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• 2023

Coastal lagoons play a crucial role in water exchange, water quality, and biodiversity. It is essential to monitor and understand the dynamics of hydrogeochemistry in lagoon water and its groundwater to preserve and sustainably manage the groundwater-dependent ecosystems like coastal lagoons. This study investigated the spatial and temporal hydrogeochemical characteristics of coastal lagoon (Songjiho) and groundwater on the east coast of Korea. The concentrations of major ions, water isotopes, and nutrients (nitrogen and dissolved organic carbon) in lagoon water and groundwater were periodically monitored for one year. The study revealed that major ions and total dissolved solids (TDS) concentration were higher at deeper depths of aquifers and closer to the coastal area. The hydrogeochemical characteristics of coastal lagoon and groundwater chemistry were classified into two types, Ca-Mg-HCO₃ and Na-Cl, based on their spatial location from inland to coastal area. Moreover, the hydrogeochemical characteristics of coastal lagoons and groundwater varied significantly depending on the season. During the wet season, the increased precipitation and evaporation lead to changes in water chemistry. As a result, the total organic carbon (TOC) of coastal lagoons increases during this season, likely due to increased runoff by rainfall whereas the variation of chemical compositions in the lagoon and groundwater were not significant because there is reduced precipitation, resulting in stable water levels and during the dry season. The study emphasizes the impact of spatial distribution and seasonal changes in precipitation, evaporation, and river discharge on the hydrogeochemical characteristics of the coastal aquifer and lagoon system. Understanding these impacts is crucial for managing and protecting coastal lagoons and groundwater resources.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.254-257
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• 2002

The purposes of this research are to identify the source and to analyze the pathway of nitrate contamination in "cultural village", Jeungpyeong. In order to examine recharge processes and flow pattern that closely related to the influent of nitrate contaminant, the flow field was simulated and the oxygen and hydrogen stable isotopes were analyzed. The nitrogen isotope was used to delineate contaminant sources. The shallow groundwater was mainly composed of precipitation, but leakage of domestic water and sewage contributed to the recharge. Nitrate contaminants were possibly from the leakage of sewage and animal waste. The nitrate concentration decreased due to dilution by low concentration water.ion water.