• 생태와환경
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• 제41권3호
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• pp.294-300
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• 2008

The stable isotopes ratios ($\delta^{13}C\;and\;\delta^{15}N$) of two coexisting species of zooplankton (Daphnia longispina and Acanthodiaptomus pacificus) and POM were determined in two alpine lakes in Japan. The difference of $\delta^{13}C$ between A. pacificus and D. longispina was 4.1$\pm$0.9‰ in Lake Shirakoma, which was larger than in Lake Panke. Whereas the difference of $\delta^{15}N$ between A. pacificus and D. longispina (2.6$\pm$0.8‰) was larger in Lake Panke than in Lake Shirakoma. $\delta^{13}C$ of POM (-26.6$\pm$1.2‰) in Lake Shirakoma was different from those of zooplankton; it was heavier than those of D. longispina and A. pacificus by 3.7$\pm$1.6‰ and 7.8$\pm$1.0‰, respectively. Whereas $\delta^{15}N$ of POM (2.0$\pm$0.8‰) was similar with those of both A. pacificus and D. longispina. This implies that the two lakes may have different trophic structure and food sources for zooplankton, and each species are grazing on selectively different components of POM. The temporal variation of $\delta^{13}C$ for each zooplankton species was associated with lipid contents of zooplankton in both lakes. The results showed that stable isotope composition of zooplankton can be an useful information for understanding energy pathways and trophic structures in lakes.

• 한국방사선학회논문지
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• 제5권1호
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• pp.5-10
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• 2011

검출한계에 대한 기본개념을 기초로 백그라운드 측정시간과 시료측정시간을 고려하였고, 환경시료중에서 육상시료(하천토, 표층토양, 식수, 지하수, 지표수, 솔잎, 쑥) 분석에서 백그라운드 계측시간과 시료 측정시간의 변화에 따른 MDA 값들을 비교하였다. 물시료 분석결과를 살펴보면 대부분 시료에서 불검출로 나타났으며, 육상시료 분석결과 대부분의 시료에서 "과학기술부고시 제 2008-28호"의 검출하한치 미만으로 측정되었으나, 일부 시료에서는 인공방사성핵종인 $^{137}Cs$이 검출되었다. 이는 과거 50.60년대 행해졌던 대기권 핵실험에 의한 낙진 및 소련의 체르노빌 원전사고 등에 의한 영향으로 우리나라뿐만 아니라 전 세계적으로 검출되고 있는 수준이다. 또한 $^{137}Cs$의 동위원소이며, 상대적으로 반감기가 짧은 $^{134}Cs$가 모든 시료에 대해서 검출되지 않는 것으로 보아 원전운영에 의한 영향이 아님을 알 수 있다.

• 자원환경지질
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• 제22권3호
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• pp.237-252
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• 1989

The Inseong gold-silver mine is located 3Km northwest of Suanbo, Choongcheongbugdo, Republic of Korea. The mine occurs in the shear zone formed by tension fractures within the Hwanggangri Formation of the Ogcheon metamorphic belt. Ore minerals found in the gold-silver bearing hydrothermal quartz vein composed mainly of pyrite, arsenopyrite, sphalerite, galena and minor amount of chalcopyrite, pyrrhotite, stannite, bismuthininte, native bismuth, chalcocite, electrum and tellurian canfieldite(?). The gangue minerals are quartz, calcite, chlorite and rhodochrocite. Wallrock alterations such as chloritization, silicitication, pyritization, carbonitization and sericitization can be observed in or around the quartz vein. According to the paragenetic sequence, quartz vein structure and mineral assemnlages, three different stages of ore formation can be recognized. The physico-chemical environment of ore formation in this deposit shows slight variation from stage to stage, but the condition of main ore deposition can be summarized as follows. Fluid inclusion, S-istope geothermometry and geothermometry based on mineral chemistry by use of arsenopyrite and chlorite show the ore was formed at temperature between 399 and $210^{\circ}C$ from fluids with salinities of 3.3-5.8 wt.% equivalent NaCl. It indicates that pressure during the mineralization is less than 0.6 Kb corresponding to a depth not greater than 1Km. S-isotope data suggests that thermal fluid may have magmatic origin wit some degree of mixing with meteoric water. In coclusion, the Inseong gold-silver deposit was formed at shallow depth and relatively high-temperature possibly with steep geothermal gradient under xenothermal condition.

• 자원환경지질
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• 제35권2호
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• pp.171-177
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• 2002

제4기 후기의 층서와 퇴적환경 변화를 조사하기 위하여 울릉분지 남서부 해역에서 채취한 푸 개의 피스톤 코어 시료를 분석하였다. 코어는 이질 퇴적물이 주종을 이루었고 일부 사질 퇴적물 및 테프라층(tephra layer)으로 구성되어 있다. 이미 확인된 울릉분지의 테프라층을 이용하여 층서 대비를 한 결과, 코어는 약 46,100년의 층서 기록을 보이며, 마지막빙기 동안의 퇴적률(12.1~14.9 cm/kyr)은 대양보다 높은 편이었다. 동위원소층서 2 동안 퇴적된 시료구간에서는 저탁류의 영향을 받은 몇 종류의 퇴적상이 교호하여 나타난다. 코어 00GHP-07의 하부구간에서는 가스 방출에 의하여 형성된 것으로 보이는 수평균열 구조가 관찰된다. 시료의 총유기탄소(TOC) 함량은 전체적으로 매우 높다(평균1.8%). 특히 총유기탄소의 값은 Termination I 동안 증가하는 추세를 보이는데, 이것은 이 기긴 동안 남서부 울릉분지가 산소가 다소 결핍한 환경으로 전이하였음을 의미한다.

• 자원환경지질
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• 제29권3호
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• pp.293-304
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• 1996

The Wolchul Mt. area is composed of a biotite granite and a pink feldspar granite. These granites are distinctly different in terms of their field occurrence, mineralogy, trace element and REE composition, as well as their isotope ages. The biotite granite has higher ferromagnesian elements and lower lithophile trace element abundances than the pink feldspar granite. The biotite granite has high Sr and Ba while the pink feldspar granite has high Rb. On the Rb-Sr-Ba diagram the biotite granite plots as a granodiorite while the pink feldspar granite belongs to a strongly differentiated granite. The ${\Sigma}$ LREE/ ${\Sigma}$ REE for the biotite granite is 0.95 and for the pink feldspar granite it is 0.88. The ratio shows a steep decrese in LREE while HREE is essentially constant. Based on the Eu/Sm, $[La/Lu]_{cN}$ and low Eu(-), the biotite granite has quartz diorite to granodiorite composition while the pink feldspar granite, with a relatively high Eu(-) anomaly, falls into the monzo- to syenogranite classification. The silica vs. trace element diagrams for the two granites indicate that the biotite granite could have formed near to a continental margin or volcanic island setting environment while the pink feldspar granite formed within a continental plate or as result of plate collision. The biotite granite has a U-Pb zircon age of 175 Ma, i.e. Middle Jurassic. The pink feldspar granite is younger, it has a K-Ar orthoclase age $93.6{\pm}1.5$ Ma which is Late Cretaceous age.

• 자원환경지질
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• 제31권2호
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• pp.149-158
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• 1998

Volcanic rocks including rhyolitic tuff, rhyolite and welded tuff in the Bupyeong silver mine area form a topographic circular structure known as a resurgent caldera. Granitic rocks are emplaced inside and outside area of the circular structure. K-Ar dating and Nd-Sr isotope studies were carried out to invesitigate the origin and petrogenetic evolution of the rhyolitic and granitic magma in the Bupeong silver mine area. Whole rock K-Ar age ranges from 208 to 131 Ma for rhyolitic rocks. Radiometric ages for the granitic rocks are 167.6 Ma for pink feldspar biotite granite from inside granitic pluton of the circular volcanic body, 178.8 Ma for the Kimpo hornblende biotite granite and 111.8 Ma for the Songdo foliated granite from outside granitic plutons of the volcanic body. The radiometric age data indicates that the volcanic activities which are partly overlapped by granite plutonic activities in the Bupyeong mine area had recorded early Jurassic and early Cretaceous in age. Initial Sr and Nd isotopic ratios of the rhyolitic rocks ($^{87}Sr/^{86}Sr$=0.710~0.719 and $^{143}Nd/^{144}Nd$=0.5115~0.5118) are similar to those of granitic rocks ($^{87}Sr/^{86}Sr$=0.709~0.716 and $^{143}Nd/^{144}Nd$=0.5115~0.5116) from inside granite stock. This means that similar source materials of felsic magma responsibles for the Bupyeong volcanic rocks and inside plutonic rocks. Based on the Nd and Sr isotopic compositions, rhyolitic and granitic magmas in the Bupyeong area originated from the partial melting of the old continental crust which has Nd model age ranging from 1500 to 2900 Ma. This is analogous to those of the other Jurassic granitoids in South Korea.

• 분석과학
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• 제17권4호
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• pp.302-307
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• 2004

환경시료중의 극미량의 악티늄계 동위원소들을 분석하기는 무척 어렵다. 이들 원소들은 개별 분리하는 작업이 필요하며, 알파분광법으로 분석한 어떤 핵종들은 검출감도도 높은 편이다. 이런 극미량의 악티늄계 동위원소들을 분석하기 위해 용매추출법이 결합된 TRU-Spec 이온교환수지와 음이온 교환수지를 사용하여 악티늄계 원소들을 분리한 후 알파분광법으로 검출하였다. 그리고 U과 Th의 검출한계를 낮추기 위해 중성자방사화분석법을 적용하였다. 중성자방사화분석법을 적용하기 위한 바탕물질로 고순도 V foil을 사용하여 검출감도를 10배 향상시킬 수 있었으며, 이 분석법을 표준시료인 NIST-4354, IAEA-368 퇴적물 시료에 적용한 결과 표준값과 10% 이내에서 잘 일치하였다.

• 한국광물학회지
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• 제18권1호
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• pp.53-59
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• 2005

예천지역 화강섬록암 풍화단면내의 흑운모가 산화흑운모로 풍화되는 과정에서 Rb-Sr 동위원소연대의 변화를 분석하였다. 신선한 흑운모와 풍화된 흑운모들의 Rb-Sr 동위원소 조성을 열이온화질량분석기로 측정하였고, 이를 기존의 K-Ar 자료와 비교하였다. Rb-Sr 동위원소연대는 흑운모의 산화정도에 따라 체계적으로 감소하는 경향을 보이며, 이는 K-Ar 연대의 감소경향과 잘 일치하였다. Fe/sup 2+/의 산화로 발생하는 과잉전하로 구조내 양이온들이 방출되는 과정에서 층간의 방사기원핵종도 일부 방출되었는데, 일가 양이온인 /sup 87/Rb이 이가 양이온인 /sup 87/Sr로 붕괴되어 딸핵종인 /sup 87/Sr이 모핵종인 /sup 87/Rb보다 심하게 흑운모로부터 제거된 것으로 보이고, 그 결과 Rb-Sr 동위원소연대가 감소하였다. 풍화된 흑운모는 모암의 연대측정대상으로 부적합한 것으로 보이지만, 풍화과정에서 방사기원 동위원소들의 거동은 흑운모 풍화의 지화학적 및 구조적 과정에 대한 유용한 정보를 제공한다.

• Journal of the korean society of oceanography
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• 제36권1호
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• pp.19-26
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• 2001

The biological pump is one of the important pumping mechanisms absorbing CO$_2$ from the atmosphere into the ocean and can be quantified by estimating new production. New production in the open ocean mostly depends on the supply of nitrate from the water below the mixed layer. While nitrate is affected by many biological processes, the helium isotope ($^3$He) is inert and has very simple physical properties. Using the $^3$He flux and the relation between $^3$He and NO${_3}\;{^-}$- within the thermocline, the nitrate flux supporting new production was estimated in the southern East Sea. The average ${\delta}^3$He within the mixed layer was -14$%_o$ and -l5.4$%_o$ in the winter and autumn, respectively. Through the year excess $^3$He occurs in the mixed layer except for a slight depletion of -17$%_o$ in summer. The $^3$He flux of 13$%_o$md$^{-1}$ associated with the concentration gradient at the air-sea interface was calculated from the product of the piston velocity and the excess $^3$He. Tritium decay within the mixed layer could support only 2$%_o$md$^{-1}$ of the flux. Thus, the remaining 11$%_o$md^{-1}$ could be attributed to the flux of tritiugenic $^3$He from the water below the mixed layer. Nitrate and $^3$He were positively correlated within the thermocline layer with the slope of 0.21 ${\mu}$mol kg$^{-1}$ $%_o\;^{-1}$. The annual nitrate flux estimated from the upward flux of $^3$He and the NO$_{3}\;{^-}$-$^3$He relation was 0.8${\pm}$0.2 mol(N) m$^{-2}$yr$^{-1}$. This flux corresponds to an annual new production of 64 g(C) m$^{-2}$yr$^{-1}$, which is consistent with that in the north-west Pacific.

• 자원환경지질
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• 제21권3호
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• pp.287-307
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• 1988

The Cheongju gold-silver mine is located at approximately $36^{\circ}28^{\prime}$north latitude and $127^{\circ}31^{\prime}$ east longitude in the Cheongju City of the Chung cheong bug Do, South Korea. Gold-Silver bearing hydrothermal quartz veins, occur in Cheongju Granit of Jurassic age. K-Ar isotope data for sericite in quartz vein indicate that the Au-Ag mineralization took place in early Cretaceous ($97.5{\pm}2.18$ MA. Park, et ai, 1986). Three stage of mineralization recognized anre, from early to later, (I) Sulide stage: pyrite, arsenopyrite, pyrrhotite (Hpo), sphalerite, chalcopyrite, electrum and quartz (II) Electrum stage: pyrite, sphalerite, galena, chalcopyrite, electrum and quartz. (III) Silver mineral stage: pyrite, marcasite, pyrrhotite (Mpo), sphalerite, galena, electrum, native silver argentite, fluorite, calcite and quartz. In this paper, mode of occurrences and chemical compositions of electum and native silver have been investigated by means of microscope and EPMA. Electron probe microanalysis shows that an individual grain of electrum is almost homogeneous in composition. Silver content of electrum ranges from 44.7-67.1 atom.%. Gold content of native silver ranges below 0.2 atom. %. Vicker's hardness number (VHN) of electrum and native silver ranges $78.2-81.8kg/mm^{2}$ respectively. The filling temperature of fluid inclusions in quartz ranges from $130-280^{\circ}C$. On the basis of arsenpyrite geothemometer, the equilibrium temperature and sulfur fugacity of the pyrite-arsenopyrite-pyrrhotite(Hpo) assemblage is assumed to be in ange from $300-310^{\circ}C$ and $10^{-10}$ to $10^{-11}$ atm. The estimated ore reserviors on Cheongju mine area are calculated to 8000 T/M, averaing 8.6g/t Au, 27.8 g/t Ag, 1.25% Pb, l.65% Zn.