• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.25 no.3
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• pp.67-80
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• 2020

Zinc (Zn) is known as an essential micronutrient for phytoplankton in the ocean. In surface waters, most of total dissolved Zn presents as organic complexes, and organic complexation dominates the speciation of Zn in seawater. Organic complexation reduces the bioavailable fraction of Zn, the free metal ion (Zn²⁺), which present less than 5% in surface waters. In this paper, a brief introduction on chemical speciation of dissolved Zn in seawater and analytical method for chemical speciation measurement is provided. Some representative studies were also introduced to describe the importance of chemical speciation of Zn (or other trace metals) on bioavailability and biogeochemistry in the ocean.

• Preventive Nutrition and Food Science
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• v.18 no.2
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• pp.139-144
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• 2013

Laver, a red algae belonging to the genus Porphyra, is one of the most widely consumed edible seaweeds. The most popular commercial dried laver species, P. tenera and P. haitanensis, were collected from Korea and China, respectively, and evaluated for proximate composition, amino acids, minerals, trace heavy metals, and color. The moisture and ash contents of P. tenera and P. haitanensis ranged from 3.66~6.74% and 8.78~9.07%, respectively; crude lipid and protein contents were 1.96~2.25% and 32.16~36.88%, respectively. Dried lavers were found to be a good source of amino acids, such as asparagine, isoleucine, leucine, and taurine, and ${\gamma}$-aminobutyric acid. K, Ca, Mg, Na, P, I, Fe, and Se minerals were selected for analysis. A clear regional variation existed in the amino acid, mineral, and trace metal contents of lavers. Regular consumption of lavers may have heath benefits because they are relatively low in fat and high in protein, and contain functional amino acids and minerals.

• Bulletin of the Korean Chemical Society
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• v.23 no.10
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• pp.1381-1391
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• 2002

The solvent sublation using ion pairs of metal-2-naphthoate(2-HNph) and tetrabutyl ammonium ($TBA^+$) ion has been studied for the concentration and determination of ultra trace Bi(III), In(III) and Tl(Ⅲ) ions in water samples. The partition coefficients ($K_p$) and the extraction percentages of 2-HNph and the ion pairs to methyl isobutyl ketone (MIBK) were obtained as basic data. After the ion pair $TBA^+$·M$(Nph)_4^-$ was formed in water samples, the analytes were concentrated by the solvent sublation and the elements were determined by GF-AAS. The pH of the sample solution, the amount of the ligand and counter ion added and stirring time were optimized for the efficient formation of the ion pair. The type and amount of optimum surfactant, bubbling time with nitrogen and the type of solvent were investigated for the solvent sublation as well. 10.0 mL of 0.1 M 2-HNph and 2.0 mL of 0.1 M $TBA^+$ were added to a 1.0 L sample solution at pH 5.0. After 2.0 mL of 0.2%(w/v) Triton X-100 was added, the ion pairs were extracted into 20.0 mL MIBK in a flotation cell by bubbling. The analytes were determined by a calibration curve method with measured absorbances in MIBK, and the recovery was 80-120%.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.1
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• pp.31-47
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• 1989

The purpose of this study was to evaluate the chemical bond strength of successively recast Pd-Ag ceramic alloys with porcelain and to investigate changes of quantity of trace elements at the metal-porcelain interface. Porcelain was fired as usual manner on the each successively recast specimen. Rectangular planar shear test was performed and bond strength was measured by Instron universal testing machine. Diffusion of trace elements at the each interface was observed by ESCA (Electron Spectroscopy for Chemical Analysis). The obtained results were as follows : 1. Chemical bond strength was significantly decreased after second recasting. But in case of first recasting, there was no significant decrease of bond strength statistically (p<0.05). 2. Bond strength was not significantly decreased in each generation, when fifty percents new alloy was added (p<0.05). 3. Ag, Sn and In were observed at the porcelain interface. But Pd was not observed. 4. The quantity of Ag, In ions were progressively increased at the metal-porcelain interface as the casting was repeated. Silver ion was most significantly increased.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4759-4775
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• 2022

The RVACS is a versatile and robust safety system driven by two natural circulations: in-vessel coolant and ex-vessel air. To observe interaction between the two natural circulations, SINCRO-IT facility was designed with two different similarity laws simultaneously. Bo' based similarity law was employed for the in-vessel, while Ishii's similarity law for the ex-vessel excluding the radiation. Compared to the prototype, the sodium and air system, SINCRO-IT was designed with Wood's metal and air, having 1:4 of the length reduction, and 1.68:1 of the time scale ratio. For the steady state, RV temperature limit was violated at 0.8% of the decay heat, while the sodium boiling was predicted at 1.3%. It showed good accordance with the system code, TRACE. For an arbitrary re-criticality scenario with RVACS solitary operation, sodium boiling was predicted at 25,100 s after power increase from 1.0 to 2.0%, while the system code showed 30,300. Maximum temperature discrepancy between the experiments and system code was 4.2%. The design and methodology were validated by the system code TRACE in terms of the convection, and simultaneously, the system code was validated against the simulating experiments SINCRO-IT. The validated RVACS model could be imported to further accident analysis.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.472-476
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• 2014

In this work, a new method that utilizes L-cysteine salicylaldehyde Schiff-base modified macroporous polystyrene resin (PS-CSC) as an effective sorbent has been developed for preconcentration of trace cadmium and lead in environmental water samples. The effect of pH, the contact time, the elution conditions, the flow rate, the initial concentration of target metal ions, and the effects of interfering ions on the preconcentration of the analytes were investigated. The maximum adsorption capacity of PS-CSC under optimum conditions for cadmium and lead were found to be 6.03 - 18.17 mg/g and 12.58 - 36.13 mg/g when the initial concentration of metal ions between 5.0 - 90 mg/L. The limits of detection for cadmium and lead were 2.46 ng/L and $0.52{\mu}g/L$, with a preconcentration factor of 200. The developed method has been validated by analyzing certified reference material and successfully applied for the enrichment and determination of trace cadmium and lead from environmental water samples.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.515-523
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• 1999

Nine trace metals (Zn, Fe, Al, Pb, Mn, Cu, Ni, Cr, and Cd) and Se concentrations were determined in organs and tissues(muscle, bone, kidney, liver and skin) of the striped field mice, Apodemus agrarius collected at Daejeo-dong, Pusan city and the Sorak Mt., Kangwon Province. All the trate elements were detected from all the mice examined. As for the metal concentrations in the mice from Daejeo-dong, Zn, Fe, Al, Mn, Ni and Cr were significantly higher than those in Sorak Mt.(p<0.05), suggesting that pesticides including Zn and factory wastes containing several metals might contaminated the environment of Daejeo-dong. As regards the element concentrations in each organ and tissue, Fe, Al, Pb, Mn, Cu, Cr and Cd concentrations were high in liver or kidney; Zn in skin and bone; Ni in bone, skin and kidney; and Se in muscle, liver and skin in all the mice examined. There were significant differences(p<0.05) between juveniles and adults in average concentration of metals(Zn, Fe, Pb, Mn, Ni, and Cd) in every organs and tissues of mice collected at Daejeo-dong. Much higher average levels of metals in juveniles indicate that considerable burdens fo metals might be transferred through the placenta. However, there were no significant differences between males and females, and between young and old adults in average metal concentrations, which suggests that the mice might accumulate the metals during their life time, although they might excrete the metals not only through reproductive activities, such as parturition, lactation and ejaculation of semen, but also through molting, judging from higher accumulating ratios of most metals in skin of adults than of juveniles.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.699-708
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• 2005

To characterize the elemental composition of fine particles in urban area, $PM_{2.5}$ was collected by a 3-stage DRUM impactor at Gwangju during spring and summer. Time and size resolved concentrations for 19 trace elements were obtained by synchrotron X-Ray fluorescence analysis. Trace elements in summer were distributed in smaller size range compared to those in spring. Almost trace element concentrations in fine particles were highly increased during the Asian dust. In spring, soil elements such as Si, K, Ca, Ti and Fe had low enrichment factors indicating the dominant influence of soil dust. However, all elements had high enrichment factors in summer implying that these elements could be emitted from the anthropogenic sources. Factor analysis was conducted with the elemental composition data in order to identify anthropogenic sources of aerosols in urban area during spring and summer. Fine particles in spring have several sources such as soil dust originating from China continental region, coal and oil combustion, biomass burning, sea salt, ferrous and nonferrous metal sources. On the other hand, fine particles in summer were influenced by road dust, gasoline vehicle as well as coal and oil combustion, sea salt, ferrous and nonferrous metal sources.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.444-450
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• 2011

A novel method that utilizes poly(5-methyl-2-thiozyl methacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid-co-divinylbenzene) [MTMAAm/AMPS/DVB] as a solid-phase extractant was developed for simultaneous preconcentration of trace Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) prior to the measurement by flame atomic absorpiton spectrometry (FAAS). Experimental conditions for effective adsorption of the metal ions were optimized using column procedures. The optimum pH value for the simultaneously separation of the metal ions on the new adsorbent was 2.5. Effects of concentration and volume of elution solution, sample flow rate, sample volume and interfering ions on the recovery of the analytes were investigated. A high preconcentration factor, 100, and low relative standard deviation values, $\leq$1.5% (n = 10), were obtained. The detection limits (${\mu}gL^{-1}$) based on the 3s criterion were 0.18 for Cd(II), 0.11 for Co(II), 0.07 for Cr(III), 0.12 for Cu(II), 0.18 for Fe(III), 0.67 for Mn(II), 0.13 for Ni(II), 0.06 for Pb(II), and 0.09 for Zn(II). The validation of the procedure was performed by the analysis of two certified reference materials. The presented method was applied to the determination of the analytes in various environmental samples with satisfactory results.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.549-554
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• 2000

This study was carried out to estimate the contents of trace metals in the fishes and shellfishes available on Korean markets. The maples were digested with acids, then analyzed by ICP (INductively Coupled Plasma Spectrometer) and AAS (Atomic Absorption Spectrometer) for the contents of lead (Pb), cadmium (Cd), arsenic (As), copper (Cu), manganese (Mn) and zinc (Zn). The contents of mercury (Hg) were determined using a mercury analyzer. The contents of trace metals [minimum~ maximum (mean), mg/kg] in fishes were as follows; Hg;0.004~0.500(0.082), Pb;N.D.~ 1.87 (0.29), Cd;N.D. ~0.094 (0.020), As;0.01~5045 (0.84), Cu;0.04~3.74 (0.66), Mn; N.D. ~7.56 (0.57), Zn;0.92~18.33(6.03). Those contents in shellfishes were as follows (mg/kg); Hg;N.D.~0.221 (0.029), Pb;0.01~1.51 (0.38), Cd;0.02~1.93 (0.51), As;0.18~3.07 study showed that trace metal contents in both fishes and shellfishes on our markets of lead, cadmium and mercury from fishes and shellfishes takes about 1~13% of PTWI(Provisional Tolerable Weekly Intakes) that FAO/WHO Joint Food Additive and Contaminants Committee has set to evaluate their safeties.