• Journal of Powder Materials
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• v.23 no.4
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• pp.325-330
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• 2016

Owing to increasing demand of rare metals present in ICT products, it is necessary to promote the rare metal recycling industry from an environmental viewpoint and to prevent climate change. Despite the fact that information for toxic substances is partly indicated, a legal basis and an international standard indicating usage of rare metals is insufficient. In order to address this issue, a newly created study group of environment and climate change at the ITU (International Telecommunication Union) is doing research to develop methodologies for recycling rare metals from ICT products in an eco-friendly way. Under this group, the Republic of Korea has established two international standards related to rare metals present in ICT products. The first is 'Release of rare metal information for ICT products (ITU-T L.1100)' and the other is 'Quantitative and qualitative analysis methods for rare metals (ITU-T L.1101)'. A new proposal for recommending the provision of rare metal information through a label by manufacturers and consumer/recycling businesses has been approved recently and is supposed to be published later in 2016. Moreover, these recommendations are also being extended to IEC, ISO and other standardization organizations and a strategy to reinforce the ability for domestic standardization is being established in accordance with industrial requirements. This will promote efficient recycling of rare metals from ICT products and will help improve the domestic supply of rare metals.

• Environmental Analysis Health and Toxicology
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• v.11 no.3_4
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• pp.45-51
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• 1996

Histopathological changes of gills and caudal fins isolated from fishes, Cyprinus carpio, Carassius auratus, and Hernibarbus labeo, which were killed by oxygen deficiency or toxic chemicals, were studied. The toxic chemicals were HCl, NaOH, chloroform, benzene, heavy metals(Cu, Cr, Zn, Pb, Hg), and o-dichlorobenzene. The exposure level was enough to kill the fishes within 30 minutes. Oxygen deficient water was prepared by aeration of nitrogen gas and the oxygen concentration was less than l ppm. Cryocutting was used for the rapid preparation of tissue slides and the tissues were stained by hematoxylin/eosin. In the fishes killed by hazardous chemicals, congestion and/or hyperplasia of secondary lamella and erosion of fin were found as the major histopathological changes. Whereas, these characteristics were not observed in gills or caudal fins of fishes killed by oxygen deficiency. These different bioindications appeared in the fishes killed by toxic substances or natural causes, can be used for the rapid identification of the causes of fish kills.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.273-274
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• 2005

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.66.2-67
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• 2000

No Abstract, See Full Text

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2020.10a
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• pp.158-158
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• 2020

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.40-43
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• 2002

Electrokinetic remediation was studied for the removal of toxic heavy metals from tailing soils. This study emphasized the dependency of removal efficiency upon heavy metal speciation, as demonstrated by different extraction methods (sequential extraction, total digestion, and 0.1 N HC1 extraction). The tailing soils examined showed different physicochemical characteristics, in view of initial pH, particle size distribution, and major mineral constituents, and contained high concentrations of target metal contaminants in various forms. The electrokinetic removal efficiency of heavy metals was significantly influenced by their partitioning prior to treatment, and by the pHs of the tailing soils. The mobile and weakly bound fractions of heavy metals, such as exchangeable fraction, were easily removed by electrokinetic treatment (more than 90% in removal efficiency), whereas immobile and strongly bound fractions, such as organically bound and residual fractions, were not effectively removed (less than 20% in removal efficiency).

• Journal of Soil and Groundwater Environment
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• v.18 no.4
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• pp.32-39
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• 2013

This research focused on the effects of heavy metals on the biomonitoring activity of genetically engineered bioluminescent bacteria, Pseudomonas putida mt-2 KG1206. KG1206 was exposed to single or binary mixtures of different heavy metals as well as soils contaminated with heavy metals. In case of single exposure with different inducer pollutant, the toxicity order was as followings : As(III) > Cd, As(V) >> Cu, Cr(VI). The toxic effects of the binary mixtures was compared to the expected effect based on a simple theory of probabilities. The interactive effects were mostly additive, while in few cases antgonistic and synergistic mode of action was observed for some concentration combinations. No considerable correlation was found between the total metal contents in soils and the bioluminescence activity of each sample. However, statistically significant differences (p = 0.0102) were observed between two groups, classified based on arsenite contamination. These results demonstrate the usage of recombinant bioluminescent microorganism in biomonitoring and the complex interactive effects of metals.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.51-64
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• 1988

It has been suggested that calcium is only one of many metals that compete with toxic metals in the body. Therefore, this study was carried out to determine the influence of water hardness on accumulation of heavy metals in rats. The seventy-five rats were divided into control and case groups. Case group was subdivided into four subgroups in proportion to the concentration of water hardness respectively, such as, 0, 250, 500, 1000ppm. Control group was fed on only deionized water, but case groups were fed on hard water with ionized heavy metals (Cd 150mg + Pb 300mg + Cu 300mg/l) for 20, 40, 60 days. The concentrations of cadmium, lead and copper were measured by atomic absorption spectrophotometry (Perkin Elmer 2380) in livers and kidneys. The results of the study are summarized as following 1. The concentration of cadmium accumulation showed the tendency of decrease in proportion to water hardness in both livers and kidneys of rats having been fed for only 60 days, respectively. 2. In only livers of rats having been fed for 60 days, essential metal, copper had the tendency of decrease according as hardness in water. 3. It was impossible to compare case with control about the tendency of lead accumulation because there was no difference between the two in livers and kidneys respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.6
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• pp.465-474
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• 2002

In order to reflect variability due to exposure factors as well as to assess uncertainty associated with cancer risk posed by airborne trace metals, a Monte Calro analysis has been made in this study. Input parameters for Monte Carlo analysis were developed or adjusted using body weight, lifetime, and exposure frequency of Koreans. Ambient distributions of toxic metals were founded to be lognormal distributions for most of them using goodness-of-fit tests. Thus, the 95% UCL and 95% LCL of carcinogenic metals were estimated by H-statistic method for lognormal distribution, respectively. The results of Monte Carlo analysis of 95% UCL showed that the 95th percentile risks for men and women were 1.2 and 1.1 times higher than an acceptable risk of 10$^{-5}$ , respectively. The probabilities which those risks exceed the acceptable risk were estimated to be 8% and 6%, respectively, while to be 95% and 94%, respectively on the basis of the minimum acceptable risk of 10$^{-6}$ , respectively. Approximately 90% of total cancer risk came from human carcinogens such as arsenic and hexavalent chromium. Therefore, it is necessary to properly manage both arsenic and hexavalent chromium emissions in the study area.

• Journal of Microbiology and Biotechnology
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• v.18 no.7
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• pp.1298-1307
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• 2008

In this study, we investigated the inhibition effects of single and mixed heavy metal ions ($Zn^{2+},\;Ni^{2+},\;Cu^{2+},\;and\;Cd^{2+}$) on iron oxidation by Acidithiobacillus ferrooxidans. Effects of metals on the iron oxidation activity of A. ferrooxidans are categorized into four types of patterns according to its oxidation behavior. The results indicated that the inhibition effects of the metals on the iron oxidation activity were noncompetitive inhibitions. We proposed a reduced inhibition model, along with the reduced inhibition constant ($\alpha_i$), which was derived from the inhibition constant ($K_I$) of individual metals and represented the tolerance of a given inhibitor relative to that of a reference inhibitor. This model was used to evaluate the toxicity effect (inhibition effect) of metals on the iron oxidation activity of A. ferrooxidans. The model revealed that the iron oxidation behavior of the metals, regardless of metal systems (single, binary, ternary, or quaternary), is closely matched to that of any reference inhibitor at the same reduced inhibition concentration, $[I]_{reduced}$, which defines the ratio of the inhibitor concentration to the reduced inhibition constant. The model demonstrated that single metal systems and mixed metal systems with the same reduced inhibitor concentrations have similar toxic effects on microbial activity.