• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.1-10
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• 2010

We used stable isotope analysis to investigate the hypothesis that zooplankton were not able to utilize Microcystis as a food source. We also studied seasonal variation of the zooplankton community in a eutrophic Wangsong reservoir. The dominant copepod species changed from Cyclops vicinus to Thermocyclops taihokuensis. Density of zooplankton was suppressed by high density of Microcystis in June and the density of phytoplankton and chlorophyll a concentration was lowest in July. The difference in $\delta^{13}C$ and $\delta^{15}N$ between cladocerans (Daphnia galeata and Bosmina longirostris) and copepods showed the maximum difference of $12^{\circ}/_{\circ\circ}$ and $4^{\circ}/_{\circ\circ}$, respectively, indicating different energy sources and trophic positions between two taxonomic groups. The difference in $\delta^{13}C$ between Microcystis and zooplankton ranged from $3{\sim}7^{\circ}/_{\circ\circ}$, supporting the hypothesis that Microcystis could not be used as food source of zooplankton.

• Journal of the Mineralogical Society of Korea
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• v.18 no.3 s.45
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• pp.165-181
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• 2005

The granitic rocks distributed in the southern part of the Yangsan Fault are classified into five distinct rock facies based on the field relation, petrography and geochemical characteristics. These five different rock facies can be grouped into two considering their origins. Group I, which reveals various evidences of magma mixing, includes three rock facies of granodiorite, enclave-rich porphyritic granite, and enclave-poor porphyritic granite. Group H intruding Croup I includes equigranular granite and micrographic granite with no evidence of magma mixing. It is suggested that the distinctively different trace element and isotopic chemistries between group I and II, support evolution from the different parental magma. It is suggested that the three rock facies in group I were generated by different degrees of magma mixing in addition to fractionation of plagioclase. MMEs experienced fractionation of biotite. The two facies in group H seem to have been generated from different parent magma from group I and evolved by fractionation of K-feldspar. The Rb-Sr whole-rock ages of the group I rocks yield $59.2\~58.9Ma$, and those of the group II rocks give 53. $3\~51.7Ma$, regardless of their distribution whether they occur in the eastern or western parts of the Yangsan Fault. Based on Sm-Nd isotope compositions, depleted mantle model ages $(T_2DM)$ of the group I range $0.8\~0.9Ga$, while those of the group II$0.6\~0.7Ga$.

• Economic and Environmental Geology
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• v.32 no.5
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• pp.455-468
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• 1999

Carbonated mineral waters fo $Ca(Mg)-HCO_3$ type spring out fissure of Jurassic granite in the valley floor of the Chungsong area. The water has been long as a Dalki medicinal water because of its unique therapeutic effect against clacium deficit, stomach and skin troubles, ect. The water has a high $CO_2$ concentration ($P_{CO_2}$=0.51~1.12atm) and exhibits strong pH buffering (5.9~6.26) by $H_2CO_3/HCO_3$ couple. Electrical conductivity ranges from 1,900 to 3100 $\mu$S/cm. Environmental isotopic data $(^{2}H/^{1}H, ^{18}O/^{16}O \;and \;^3H)$ indicates that the water is of meteoric origin recharged in the Cretaceous sedimetary strata distributed in upper part of the catchment area at least before 1950s, The high $P_{co_2}$ and carbon isotope data (${\delta}^{13}C=-3\sim-0.2\textperthousand$) suggest that the potential source of carbonated mineral water was originated in deep-seated $CO_2$ as wel as aboundant carbonate minerals of sedimentary desimetary rocks. The major source minerals of the dissoved species in the carbonated mineral water appear to be carbonate minerals, albite and K-feld-spar in sedimentrary rocks.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.317-333
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• 2014

The Pocheon iron (-copper) deposit, located at the northwestern part of the Precambrian Gyeonggi massif in South Korea, genetically remains controversial. Previous researchers advocated a metamorphosed (-exhalative) sedimentary origin for iron enrichment. In this study, we present strong evidences for skarnification and Fe mineralization, spatially associated with the Myeongseongsan granite. The Pocheon deposit is composed of diverse carbonate rocks such as dolostone and limestone which are partially overprinted by various hydrothermal skarns such as sodic-calcic, calcic and magnesian skarn. Iron (-copper) mineralization occurs mainly in the sodic-calcic skarn zone, locally superimposed by copper mineralization during retrograde stage of skarn. Age data determined on phlogopites from retrograde skarn stage by Ar-Ar and K-Ar methods range from $110.3{\pm}1.0Ma$ to $108.3{\pm}2.8Ma$, showing that skarn iron mineralization in the Pocheon is closely related to the shallow-depth Myeongseongsan granite (ca. 112 Ma). Carbon-oxygen isotopic depletions of carbonates in marbles, diverse skarns, and veins can be explained by decarbonation and interaction with an infiltrating hydrothermal fluids in open system ($XCO_2=0.1$). The results of sulfur isotope analyses indicate that both of sulfide (chalcopyrite-pyrite composite) and anhydrites in skarn have very high sulfur isotope values, suggesting the $^{34}S$ enrichment of the Pocheon sulfide and sulfate sulfur was derived from sulfate in the carbonate protolith. Shear zones with fractures in the Pocheon area channeled the saline, high $fO_2$ hydrothermal fluids, resulting in locally developed intense skarn alteration at temperature range of about $500^{\circ}$ to $400^{\circ}C$.

• Korean Journal of Ecology and Environment
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• v.57 no.1
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• pp.39-50
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• 2024

In ecosystems within limited resources, interspecific competition is inevitable, often leading to the competitive exclusion of inferior species. This study aims to provide foundational information for the conservation and restoration management of Microphysogobio rapidus by evaluating species' ecological response to biological factors within its habitat. To understand this relationship, we collected food web organisms from site where M. rapidus coexist with Microphysogobio yaluensis, a specie ecologically similar to M. rapidus, and evaluated the trophic levels (TL), isotopic niche space (INS), and the overlap of INS among fishes within the habitat using stable isotope analysis. Our analysis revealed that the M. rapidus exhibited a higher TL than M. yaluensis, with TL of 2.6 and 2.4, respectively. M. yaluensis exhibited a broad INS, significantly influencing the feeding characteristics of most fish. Conversely, M. rapidus showed a narrow INS and asymmetric feeding relationships with other species, in habitats with high competition levels. This feeding characteristics of M. rapidus indicate that the increase in competitors sharing the similar resources lead to a decrease in available resources and, consequently, is expected to result in a decrease in their density.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.183-191
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• 2013

Dissolved organic carbon (DOC) concentrations and zooplankton and particulate organic matter (POM) ${\delta}^{13}C$ values were measured in five reservoirs in Korea. Zooplankton ${\delta}^{13}C$ and POM ${\delta}^{13}C$ showed large range from -33‰ to -22‰ and a significant difference among the reservoirs. One eutrophic reservoir, Lake Masan, showed unique characteristics with the highest zooplankton density, the highest ${\delta}^{13}C$, and the highest DOC. Zooplankton ${\delta}^{13}C$ was similar to POM ${\delta}^{13}C$, implying that zooplankton occupies substantial portion of POM or that zooplankton isotopic composition is related to selective grazing and assimilation of food sources from bulk POM. Except Lake Masan zooplankton ${\delta}^{13}C$ values were negatively correlated to DOC concentration in four reservoirs with mostly forest land use. This pattern can be probably attributed to intensive agricultural land use in the watershed of Lake Masan compared to the mostly forest land use in the other watersheds. Understanding the relationship between zooplankton ${\delta}^{13}C$ values and the origin of organic matter associated with watershed characteristics will be valuable to better understand trophic relationships in reservoirs in the summer monsoon region.

• Analytical Science and Technology
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• v.21 no.3
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• pp.201-211
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• 2008

The treatment efficiency of PCBs containing wastes has been investigated. The samples treated by electron beam and de-chlorination method were analyzed to verify the byproducts before treatment and after treatment. In the treated samples by electron beam irradiation, PCBs were not detected by comparing the peak matching using the Korean official waste test method. On the other hand, PCBs congeners were detected by analyzing individual isotope method using HRGC/HRMS. Most of PCB congeners in waste were decomposed to 3-chlorobiphenyls, lower chlorinated congener produced during the treatment of electron beam. In the chemical dechlorination treatment, it was found that the concentrations of PCBs in treated samples were lower than those of regulation criteria in Waste & POPs management law and the after treatment concentration were satisfied to the regulation criteria. Also, dioxins were not observed after the physio-chemical treatment processes of PCBs containing wastes.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.623-633
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• 1995

The Beonam deposits which is located in south-western part of Sobaeksan massif are emplaced along $N20{\sim}30^{\circ}E$ trending fissures in Precambrian Sobaeksan gneiss complex. Surrounding granites are inferred to be differentiated and formed from calc-alkaline magma which was generated from remelting or partial melting of the crustral material having igneous composition. The Sr isotope data of ore minerals showing significantly low initial Sr value relative to those of surrounding granite batholiths suggest that the ore-bearing fluid formed the Beonam Au-Ag mine are isotopically distinct from those of the wall rocks, and it indicates that there is no evidence of genetic relationship between ore-bearing fluids and surrounding granites, although further study should be needed. The results of paragenetic studies suggest three stages of hydrothermal mineralization; stage I: base-metal sulfides stage, stage II: late base-metal sulfides, electrum and silver-bearing sulfosalts stage, stage III: minor silverbearing minerals, barren quartz and carbonates stage. The temperature, salinity and pressure of the Beonam deposits estimated from mineral assemblage, chemical composition, fluid inclusion and sulfur isotope geothermometry are as follows; stage I: $200{\sim}315^{\circ}C$, 3.5~6.5 NaCl eq. wt%, 0.28~0.61 Kbar, stage II: $150{\sim}235^{\circ}C$, 4.5~7.4 NaCl eq. wt%, 0.11~0.15 Kbar. The estimated oxygen and sulfur fugacity during first stage mineralization, based on phase relation of associated minerals, range from $10^{35.1}{\sim}10^{-39.7}$ atm. and $10^{-11.0}{\sim}10^{-13.4}$ atm., respectively. All these evidences suggest that the Beonam deposits are polymetallic meso-epithermal ore deposits.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.59-59
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• 2017

Rice (Oryza sativa L.) is the most important crop and its yield must be improved to feed the increasing global population. Recently developed high-yielding varieties with extra-large sink capacity often have a problem in unstable grain-filling. Therefore, understanding limiting factors for improving grain-filling and controlling them are essential for further improvement of rice grain yield. However, since grain-filling rate was determined by complex sink-source balance, the ability of grain-filling was very difficult to evaluate. Source ability for 'grain' was not only determined by the ability of carbon assimilation in leaves, but also that of carbon translocation from leaves to panicles. Sink strength was determined by the complex carbon metabolism from sucrose degradation to starch synthesis. Hence, to evaluate the grain-filling ability and determine its regulatory steps, the whole picture of carbon flow from photosynthesis at leaves to starch synthesis at grains must be revealed in a metabolite level. In this study, the yield and grain growth rate of three high-yielding varieties, which show high sink capacity commonly, were compared. Momiroman showed lower grain filling rate and slower grain growth rate than the other varieties, Hokuriku 193 and Tequing. To clarify the limiting point in the carbon flow of Momiroman, $CO_2$ labeled by stable isotope ($^{13}C$) was fed to three varieties during ripening period. The ratio of $^{13}C$ left in the stem was higher in Momiroman 24 hours after feeding, suggesting inefficient carbon translocation of Momiroman. More interestingly, $^{13}C$ translocation from soluble fraction to insoluble one in the grain seemed to be slower in Momiroman. To get the further insight in a metabolite level, we are now trying the $^{13}C$ labeling metabolome analysis in the developing grains.

• Economic and Environmental Geology
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• v.32 no.5
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• pp.469-483
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• 1999

Two different types of deep groundwaters occur together in the Jungwon area: $CO_2$-rich water and alkali water. Each water shows distrinct hydrogeochemical and environmental isotopic characteristics. The $CO_2$-rich waters are characterized by lower pH(6.0~6.4), higher Eh (25~85mV) and higher TDS content (up to 3,300 mg/l), whereas the alkali type waters have higher pH (9.1~9.5), lower Eh (-136~-128mV) and lower TDS content (168~254 mg/l). The CO2-rich waters ($Pco_2$=up to 1atm) were probably evolved by the local supply of deep $CO_2$ during the deep circulation, resulting in enhanced dissolution of surrounding rocks to yield high concentrations of $Ca^{2+}, Na^+, Mg^{2+}, K^+\; and \;HCO_3\;^-$ under low pH conditions. On the other hand, the alkali type waters ($Pco_2$=about 10-4.6 atm) were evolved through lesser degrees of simple wate/rock (granite) interaction under the limited suppy of $CO_2$. The alkali waters are relatively enriched in F- (up to 14mg/l), whereas the F- concentration of$CO_2$-rich water is lower (2.2~4.8 mg/l) due to the buffering by precipitation of fluorite. The oxygen-hydrogen isotopes and tritium data indicate that compared to shaltion ($\delta$18O=-9.5~-7.8$\textperthousand$),two different types fo deep groudwaters (<1.0TU)were both derived from pre-thermonuclear (more than 40 years old) meteoric waters with lighter O-H isotopic composition ($\delta$18O=-9.5~-7.8$\textperthousand$) and have evolved through prolonged water/rock interaction. The $CO_2$-rich waters also show some degrees of isotopic re-equilibration with $CO_2$ gas. The $\delta^{34}S$ values of dissolved sulfates (+24.2~+27.6$\textperthousand$) in the $CO_2$-rich waters suggest the reduction of sulfate by organic activity at depths. The carbon isotope data show that dissolved carbon in the $CO_2$-rich waters were possibly derived either from dissolution of calcite or from deep $CO_2$ gas. However, strontium isotope data indicate Ca in the $CO_2$-rich waters were derived mainly from plagioclase in granite, not from hydrothermal calcites.