• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.422-423
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• 2006

Ultrasonic-milling of metal oxide nanopowders for the preparation of tungsten heavy alloys was investigated. Milling time was selected as a process variable. XRD results of metal oxide nanopowders ultrasonic-milled for 50 and 100h showed that mean crystallite size reduced with increasing milling time and there was no evidence of contamination or change of composition by impurities. It was found that nanocomposite powders reduced at $800^{\circ}C$ in $H_2$ atmosphere had a composition of 93.1W-4.9Ni-2.0Fe by EDX analysis. Hardness of sintered samples of 50 and 100h was 390 and 463 Hv, respectively, which corresponds to the hardness of commercial products.

• Journal of Korean Society on Water Environment
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• v.37 no.4
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• pp.296-305
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• 2021

This work investigated heavy metal pollution in surface sediments of rivers in Busan, Korea. Surface sediments were analyzed in order to conduct contamination assessment of organic matter, nutrients, and heavy metal concentrations. Contamination assessment of heavy metals was conducted using geoaccumulation index (I_geo), pollution load index (PLI), and potential ecological risk index (RI). Accumulation of organic matter and nutrients were affected by water discharged from sewage treatment plant. The concentrations of organic matter and nutrients were found to be greater in points which were close to the sewage treatment plant more than points furthest. The concentrations of Pb, Zn, Cu, Cd, Hg, As, Cr, and Ni were found to be greater in surface sediment more than in the background. The mean concentrations of heavy metals were in the order of Zn (323.5 mg/kg) > Cu (70.5 mg/kg) > Pb (39.8 mg/kg) > Cr (33.4 mg/kg) > Ni (13.5 mg/kg) > As (9.4 mg/kg) > Cd (0.84 mg/kg) > Hg (0.092 mg/kg). The result of geoaccumulation indices indicated that Hg > Cr > Cu > Ni > Zn > As > Pb > Cd were found in order of severe contamination by heavy metals. From PLI and RI analysis, it was evident that the Suyeonggang 2 was the most contaminated river.

• Journal of Korea Soil Environment Society
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• v.1 no.2
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• pp.23-34
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• 1996

The biological magnification of Pb, Cu, Zn and Fe in vascular plant, Persicaria thunbergii, Trapa japonica and Nymphoides peltata natually grown at the river and riverside and relationship between the concentration of heavy metals in these vascular plants and in the soil were investigated in the Chonju river, Chonju city. The biological magnification values of these metals in P thunbergii were founded as follows ; Pb, Cu, Zn and Fe were 80.4~254.6$mu\textrm{g}$/g, 284.6~688.4$mu\textrm{g}$/g, 635.5~1979.4$mu\textrm{g}$/g and 1160.0~3590.9$mu\textrm{g}$/g respectively. In the case of T. japonica, Pb, Cu, Zn and Fe were 107.8~306.0$mu\textrm{g}$/g, 282.7~963.0p$mu\textrm{g}$/g, 1328.3~3546.$mu\textrm{g}$/g and 656.8~9944.0$mu\textrm{g}$/g and in N. peltata, 140.1~ 193.9$mu\textrm{g}$/g, 187.7~327.3$mu\textrm{g}$/g, 1126.6~1723.6$mu\textrm{g}$/g and 611.7~1914.6$mu\textrm{g}$/g respectively. The amount of the biological magnification of heavy metals in the leaf, stem and root of these plants was generally increased in the sequence of leaf

• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.967-973
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• 1993

The effect on the hydration of cement was that Cu and Pb reacted with alkali to form soluble hydrates at theinitial stage and then there followed a slow reaction forming insoluble metal hydroxides. These hydroxides were deposited on the surface of cement particles providing a barrier against further hydration. But as a slow reaction continued, the insoluble layers were eventually destroyed and the hydration reaction resumed. Thereafter, another retardation occured by restricting the polymerization of silicates, shown by FT-IR spectroscopy analysis. In the case of Cr, as its reaction with cement caused H2O, the coordinator of Cr complex, to replace or polymerize with OH-, the formation of Cr complex promoted the leakage of OH- and increased the heat of dissolution. So the total heat evolution during hydration was larger than that in the case of Pb or Cu. The retarding effect of heavy metal ions was in the order Pb>Cu>Cr.

• Journal of the Korean Geosynthetics Society
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• v.13 no.2
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• pp.59-67
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• 2014

The amount of the contaminants that can be adsorbed on the drain was evaluated for the effective remediation of the contaminated soil, and the contaminants adsorptivity of the drain was evaluated by comparing the isothermal adsorption model after carrying out the contaminants adsorption test of the reactants coated on the surface of the drain. The reactant used in the experiment is a natural zeolite, and the contaminants are copper, lead and cadmium. The results that Freundlich and Langmuir adsorption isotherm model are compared to the adsorption amount according to the change of the initial concentration by the contaminants. As a result of the component analysis, because Si, Al and O are contained approximately 28%, 11% and 48%, respectively, it is identified that the material coated on the surface of the drain is the component of the zeolite which is the reactant for the adsorption of the heavy-metal (Cu, Pb, Cd) contaminants. The heavy-metal adsorption kinetic of the zeolite which is the reactant was decreased in order of lead, copper and cadmium. The important factor of the performance evaluation of the adsorbent is the reaction rate, and if zeolite is used as the reactant in the relationship between the maximum amount of adsorption and reaction rate, it can be utilized as the design factor that determine the removal order of the complex heavy-metal. In other words, because the maximum adsorption quantity of lead is smaller compared to copper but the reaction rate is relatively fast, it can be primarily removed, and copper can be removed after removing the lead. It was analyzed that Cadmium can be finally removed after that other heavy-metal is removed.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.265-276
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• 2017

Heavy metals leaching from closed mines have been causing severe environmental problems in nearby soil ecosystems. Mine reclamation in Korea has been recently implemented based on the heavy metal immobilization (a.k.a., stabilization). Since the immobilization temporarily fixes the heavy metals to the soil matrix, the potential risk of heavy metal leaching still exists. Therefore the appropriate monitoring and the related policies are required to safeguard the soils, where all the cultivations occur. The current monitoring methods are based on either heavy metal concentration or simple toxicity test. Those methods, however, are fragmented and hence it is difficult to evaluate the site in an integrated manner. In this study, as the integrated approach, ecological functional state evaluation with a multivariate statistical tool was employed targeting physiochemical soil properties, heavy metal concentrations, microbial enzymatic activity, and arsenic respiratory reductase gene quantity. Total 60 soil samples obtained from three mines (Pungjeong, Jeomdong, Seosung) were analyzed. As a result, the stabilized layer soil and lower layer soil have shown the similar pattern in Pungjeong mine. In contrast, Jeomdong and Seosung mine have shown the similarity between the stabilized layer soil and the cover layer soil, indicating the possible contamination of the cover layer soil.

• 한국해양학회지
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• v.18 no.1
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• pp.29-42
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• 1983

This stidy was intended to investigate the heavy metal contents in the bottom sediments of the continental shelt around the Jeju Island and ot the southern coastal area of the Korean Peninsula. For this study 39 bottom sedinent samples were taken from the study area using Phleger gramity corer and Snapper. The average contents of heavy metals were 59.1 ppm Zn, 362.6 ppm Mn, 63.8 ppm Cr, 15.7 ppm Pb, 10.0 ppm Co, 28.9 ppm Ni, 10.5 ppm Cu, and 2.7% Fe in the surficial sediments around the Jejr Island; and 79.ppm Zn, 384 ppm Mn, 8.6 ppm Pb, 17.8 ppm Ni, 23.2 ppm Cu, and 1.59 % fe in those of nearsgore of the southern coastal area respectively. The heavy metal contents were higher in the northwestern part around the Jeju Island compared to those in other region. However, these tendencies were not the result of pollution, but of the differences of grain size of the sedimenrs. In the nearshore of the southern coast, the heavy metal contents did not show any geographical tendency. However, those of Masan and Jinhae Bays wew higher than those of the other region. These seemed to be caused by waste disposal from the industrial compsex located at the adjacent land. Nevertheless these values of heavy metal content except for Zn and Cu in Masan Bay and inner bay of Jinhae are lower than the average values of the each world-wide data of the nearshore sedimentl. The pair correlations of the cach heavy metal elements were calculated by regressino analysis using VAX 780 computer. the following pair elements, such as Zn-Cu, Ni-Cu, Fe-cu, Cr-Cu, Co-Zn, Ni-Zn, Cr-Zn, Ni-Co, Fe-Co, Cr-Co, Fe-Ni, Cr-Ni and Cr-Fe show closely posetive linear correlations in the sediments around the Jeju Island. In general, the heavy metal content increases in proportion to the increase of the mean values of the grain size of the sediments around the Jeju Island. In the southern coastal area, in gineral, thepair correlations of each heavy metal elements did not southern coastal area, in general, the pair correlatttttions of rach heavy metal elements did not show any positive correlation except for the positive linear correlations of Cu-Zn, Cu-ni and Ni-Mn. It is interpreted as a result of the differences of the physecochemical environment of the sampling sites and also of the influences of the ondustrial wastes from the manufacturing factores located at the coastal zone of the study area.

• Environmental Analysis Health and Toxicology
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• v.4 no.1_2
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• pp.35-45
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• 1989

Studies on the heavy metal content of ginkgo leaves growing in all around Seoul. This study was carried out to investigate the concentration of heavy metals and soluble sulfur in ginkgo leaves. These leaves are found growing in park, residential, commercial and industrial areas all around Seoul. These analyzed the quantity of Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn, Hg and soluble surfur in separate samples of washed and unwashed leaves. The results were as follows: 1. This order of heavey metal concentration was found in Seoul area,: Fe＞Mn＞Zn＞Ni＞Pb＞Cu＞Co＞Cd＞Hg. 2. Pb concentration was higher in the commercial area than in the other areas, and it concentration in washed leaves was higher 96～100% and unwashed leaves 85～170%. 3. In the residential area Ni concentration was significantly higer where about seven times more Ni as found on the top part of the leaves. 4. Water soluble surfur was higest in the inudstrial area, but the percentage on top of the leaves was only 0.04～0.05% simillar with other area. 5. Fe, Zn and Ni were almost positively correlated to each component but negatively correlated between Mn and souble sulfer. All of content except Mn and Ni were significance between each area in washed and unwashed leaves.

• Environmental Analysis Health and Toxicology
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• v.19 no.2
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• pp.183-189
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• 2004

To obtain the residual organochlorine pesticides in the culture environment of ginseng on Sangju, Gyeongbuk, the analytical methods for BHC isomers, Aldrin, DDE, Dieldrin, DDD, Endrin and DDT by GCECD are surveyed. The relative retention times for $\alpha$-BHC, $\beta$-BHC, ${\gamma}$-BHC, $\delta$-BHC, Aldrin, DDE, Dieldrin, DDD, Endrin and DDT were 1.000, 1.042, 1.049, 1.086, 1.202, 1.335, 1.341, 1.371, 1.391 and 1.439, respectively The BHC isomers, Aldrin, DDE, Dieldrin, DDD, Endrin and DDT were separated on the base line. The qualified detection concentration for $\alpha$-BHC, $\beta$-BHC, ${\gamma}$-BHC and $\delta$-BHC is 0.43, 1.33, 0.54 and 1.63 ng/g and it's of Aldrin, DDE, Dieldrin, DDD, Endrin and DDT were 0.63, 0.50, 0.66, 0.74, 0.96 and 0.88ng/g, respectively. BHC isomers, Aldrin, DDE, Dieldrin, DDD, Endrin and DDT were not detected in culture environment of ginseng on Sanaju, Gyeongbuk. The detection concentration for Hg, Cd, Pb, Cr, and As in ginseng were 0.0086ppm, 0.0020ppm, 0.0200ppm, 0.0271ppm and 0.0220ppm, respectively, which were also lower than the 30ppm Korea Food & Drug Administration advisory level for heavy metal in herbal medicines.

• Journal of Society of Preventive Korean Medicine
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• v.13 no.1
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• pp.93-103
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• 2009

Evidences from various countries suggest that toxic heavy metals in herbal medicine may constitute a serious health problem. In order to evaluate whether the toxic heavy metals caused by herbal medicine intake, blood samples collected from 222 patients taking herbal medicine were analyzed. In average levels of analyzed metals, $0.4{\sim}33.9%$ of total samples for 8 metals such as Cd, Co, Cu, Hg, Mn, Ni, Pb and Zn except Cr and Fe exceeded the upper limit for WHO reference value. In analysis of regression coefficients indicating the levels of metals increased or decreased after taking herbal medicine for one month, however, there were different aspects by intake types for herbal medicine. For example, the metals increased by taking decoction in blood samples were as follows; Cd and Pb whether Mn, Ni and Pb as increased metals were identified in the group taking pill and decoction(combined intake group). The odds ratio showing values higher than 1 indicating that people who take herbal medicine would have possibility higher for metal accumulation in blood than that from people who do not take herbal medicine. The metals showing the odds ratio higher than 1 were Hg and Ni in decoction group, and Cd and Hg in combined intake group. However, eight of the total, 10 metals showed the odds ratios lower than 1 by taking herbal medicine. Thus, this may explain the possible role of herbal medicine as a chelator for heavy metals in body.