• Korean Journal of Soil Science and Fertilizer
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• v.37 no.6
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• pp.371-377
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• 2004

Sulfate adsorption in forest soils is a process of sulfur dynamics playing an important role in plant uptake, cation movement, acid neutralization capacity and so on. The relationship between sulfate adsorption and some physicochemical properties of four forest soils was investigated. Extractable sulfate contents and sulfate adsorption capacity (SAC) in the forest soils varied much among study sites. Extractable sulfate contents were more in sub-surface soils with lower organic matter and greater Al and Fe oxides than in surface soils. The average contents of $Al_d$ and $Fe_d$ in the sub-surface soils were 8.49 and $12.45g\;kg^{-1}$, respectively. Soil pH, cation exchange capacity and clay content were positively correlated with the extractable sulfate contents and SAC. Organic carbon content, however, was negatively correlated with the extractable sulfate contents, implying the competitive adsorption of sulfate with soil organic matter. Considerably significant correlation was found between inorganic + amorphous Al and Fe oxides and the sulfate adsorption, but crystalline Al and other fractions of Fe oxide showed no correlation. Relatively close relationship between the adsorbed sulfates and soil pH, cation exchange capacity, or amorphous Al oxides indicates that the accelerated soil acidification may substantially reduce the potential for sulfate adsorption contributing to sulfur flux in forest ecosystems.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.482-486
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• 2004

울산지역 수질특성에 관하여 연구하기 위해 228개 지점에서 수질성분 25개 항목을 분석하였다. 그 성분중 지하수 음용수 9개 수질성분(pH, EC, TDS, Cl, Mn, NO$_3$, SO$_4$, F, Fe)에 관해 수질분포특성 및 오염도를 나타내기 위해 모수적 통계기법인 정규크리깅과 비모수적 통계기법인 지시크리깅 기법을 적용하였다. OK와 IK의 성분별 베리오그램 분석한 결과 OK의 경우 모든 수질성분은 구상형모델(Spherical model)로 선정되었으며, IK의 경우 pH, TDS, SO$_4$, Cl, Mn, F, Fe 성분은 구상형모델로, EC는 지수형모델로, NO$_3$는 선형모델로 선정되었다. 그 결과 정규크리깅의 경우 연구지역의 수질특성을 정량적 분포특성이 잘 나타났다. 특히 태화강, 인접한 남구일원과 중구일원, 북구의 북서 일원 그리고 동구의 방어동일원에서 수질성분 9개 성분들이 다소 높게 나타났다. 특히 EC, TDS 그리고 Cl$^{-}$ NO$_3$ 성분이 높게 나타났다. 그리고 지시크리깅의 경우 정규크리깅과 비교하여 이상치가 크게 영향을 미칠 수 있는 통계학적인 오류를 보완하여 분석한 결과 울산지역 9개 성분 오염도는 EC>TDS>NO$_3$>pH>Fe>Mn>Cl>SO$_4$>F 순으로 오염특성이 나타났다.

• Journal of Nutrition and Health
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• v.17 no.1
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• pp.31-40
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• 1984

A new microassay was proposed for the determination of serum thiobarbituric acid(TBA) value greatly enhanced by ferric ion under anaerobic condition. One ${\mu}mole$ of $FeCl_{3}$ per $10{\mu}l$ of serum was added to the TBA reaction mixture containing serum protein precipitate. The reaction mixture was heated on boiling water-bath for 50min under $N_{2}$ flushing. The sensitivity of this assay was greatly enhanced by 40 times comparing with that of Yagi's method (1976). In favour of the enhancement, this test could be measured by colorimetry or spectrophotometry with the sample size of $10-20{\mu}l$ serum. The sensitivity and reproducibility were also improved by means of partial dehydration of the butanol extract with $(NH_{4})_{2}SO_{4}$ salting-out. Serum TBA values of healthy human at different age groups were determined by this proposed method.

• YAKHAK HOEJI
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• v.31 no.6
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• pp.402-404
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• 1987

Fermentation processes have been employed to produce 17-ketosteroids from sterol with chelator of Fe$^{2+}$ such as $\alpha$, ${\alpha}'$-dipyriyl. To analyze the products of sterol fermentation, we developed a simple TLC method without interference of the chelator $\alpha$, ${\alpha}'$-dipyridyl, using Ag$^+$ band on TLC plate.

• Analytical Science and Technology
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• v.6 no.3
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• pp.329-334
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• 1993

The formation of Mo(VI)-alizarin red S chelate ion its extraction into an organic solvent by ion-pairing for the separarive determination of trace Mo(VI) in natural water was applied in seawater samples. Removed Fe(III) and Zn(II), and Cu(II) by precipitating with anthranilic acid at pH 4.0 and 2.0, seawater 100mL was sampled in 250mL separatory funnel. After Mo(VI)-ARS chelate ion was formed by adding 0.01M alizarin red S solution 1.0mL to the water sample of pH 4.6, 0.6% aliquat-336 chloroform solution 10mL was added and the solution was vigorously shaked for about 30 seconds to form the ion-pair between Mo(VI)-ARS and aliquat-336 perfectly. The solution was stood for about 30 minutes. And the organic phase was taken for the absorbance measurement of the ion-pair at 520nm. The content of Mo(VI) was obtained from the standard calibration curve. Several extraction conditions such as pH, adding amounts of alizarin red S and aliquat-336, and shaking and standing times were optimized and the interferences and release of concomitant ions was also studied. This procedure was applied to the analysis of Eastern and Yellow seawaters. It could be confirmed from the recoveries of over 85% in samples spiked with a given amount of Mo(VI) that this method was also quantitative in the determination of trace Mo(VI) in a seawater.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.327-333
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• 1993

A method was developed for the determination of trace elements in seawater by precipitate flotation preconcentration and subsequent flame atomic absorption detection. In order to quantitatively coprecipitate trace ions such as Cd(II), CuI(II), Fe(III), Mn(II), Pb(II) and Pd(II), 2.0 ml of 1.0M cerium(III) solution was added to 1.0l of seawater and the pH was adjusted to 9.5 with 5.0 M sodium hydroxide solution while stirring with a magnetic stirrer. The precipitate was floated with the aid of surfactant solution (1.0 ml of 0.3% sodium oleate) by bubbling nitrogen gas through a porous (No. 4) fritted glass disk. The floats was collected in a small Erlenmeyer flask by suction. The washed precipitate was dissolved in 8.0 M nitric acid and marked with deionized water in the volumetric flask of 10.0 ml. The analyte was determined by measuring the atomic absorbances in 100-fold concentrated solution. Above all analytes in Kangnung (East Sea) and Kanghwado (West Sea) sea waters were found to be under the detection limit of this method. The recoveries of over 92% for all analytes spiked into seawater samples showed that this method was applicable to the analysis of real seawater.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.314-321
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• 2000

A gap between a $Al_2O_3/Fe$ thermite and lower head vessel is formed in the lower-plenum arrested vessel attack(LAVA) experiment which is the 1st phase study of simulation of naturally arrested vessel attack in vessel(SONATA-IV). The gap measurement using a conventional ultrasonic method would be lack of a reliability due to the structure complexity and the metallurgical grain size change of the lower head HAZ occurred by a thermite $Al_2O_3/Fe$ melt or a $Al_2O_3$ melt at $2300^{\circ}C$. The grain echoes having false signals and lower S/N ratio signals are detected due to a multiple scattering, a mode conversion and an attenuation of a ultrasonic resulted from at the interface of increased grain size zone. In this test, the signals pattern was classified to understand the behavior of the ultrasonic in a multi-layer specimen of solid-liquid-solid of assuming that the thermite and the lower head vessel is immersed. The polarity threshold algorithm of frequency diversity gives us the enhancement about 6dB of the ratio S/N.

• Economic and Environmental Geology
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• v.26 no.2
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• pp.117-127
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• 1993

Ag-Au vein ores from the Weolyu mine, Youngdong district, contain significant germanium (up to 145g/t, average 34.9g/t), in the form of argyrodite ($Ag_8GeS_6$). Mineral chemistries of argyrodite and its associated minerals were determined by electron probe microanalysis. Twenty eight elements in thirteen ore samples were analyzed using an ICP mass spectrometer. Argyrodite occurs in the paragenetically later mineral assemblage consisting of carbonates+quartz+native silver+argentite+Ag-sulfosalts, indicating that the germanium mineralization represents the culmination of a complex mineral sequence which includes early gold and late silver deposition. The mean formula of the argyrodite is $Ag_{7.90}\;(Ge_{0.76}Sn_{0.04})S_6$, with minor amounts of Cu, Fe, Sb, As, Sn, and Zn. The Weolyu argyrodite shows systematic substitutions of Ag by Cu, and of Ge by Sb. Chemical analyses of vein ores indicate that metals were precipitated in the order of $Fe{\rightarrow}Pb$, $Zn{\rightarrow}Cu{\rightarrow}Ag$, Sb, As, Ge. Germanium has a strong geochemical affmity with As and Sb, and Cu, Pb, Zn, Mo, and Sr show weak positive correlations with Ge. Germanium deposition at Weolyu was mainly a result of cooling of hydrothermal fluids (down to $175^{\circ}C{\sim}210^{\circ}C$, due to increasing involvement of cooler meteoric waters in the epithermal system.

• Analytical Science and Technology
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• v.14 no.5
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• pp.410-415
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• 2001

An analytical method has been developed which determines lead in steel samples by inductively coupled plasma mass spectrometry (ICP-MS) with sample introduction by the hydride generation. The lead hydride is not stable and requires and oxidant for the oxidation into metastable Pb(IV) before reduction to $PbH_4$ with $NaBH_4$. A study was carried out to find and optimum lead hydride generation condition for a sample solution with more than $1000{\mu}g/mL$ Fe matrix. $K_2Cr_2O_7$ was found to work as an efficient oxidant when more than $10{\mu}g/mL$ Fe matrix was present. Lactic acid was used with the oxidant as a complexing agent of the metastable Pb(IV) to enhance sensitivity. Optimum concentrations of the sample acidity, oxidant and lactic acid were different depending on the matrix concentration. The isotope dilution method was employed for the quantitation of lead. The determined Pb concentrations of the NIST steel SRM 361 and 362 were in good agreement with the certified values within the uncertainty range.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.186-190
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• 1995

A simple procedure, readily available at low cost with a sensitivity sufficient to determine trace levels of iron in seawater is proposed, which utilizes adsorptive accumulation of the iron/catechol complex on the mercury drop electrode in a borate medium of pH 8.0. Optimal conditions include a solution concentration of 2 mM catechol, 2.5 mM borate and a pH of 8.0, an accumulation potential of - 0.25 V is applied for 1∼3 min, and the potential scan is in the differential pulse mode. The limit of detection is 1.5 nM Fe using a preconcentration time of 3 min. The interference from copper can be eliminated and baseline slope is greatly improved, because its peak is well separated from that of iron in the proposed medium.