• Journal of the Korean Society of Groundwater Environment
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• v.4 no.4
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• pp.169-174
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• 1997

Stream water and precipitates were analyzed for metal contents to evaluate the compositional changes of effluent water from mine waste Danbung mine located in the vicinity of Munkyung. Samples were collected before and after the rainy season in 1995 and before the rainy season in 1997 to observe seasonal variation and the charge of the status of pollution after the lapse of two years. Increased metal contents and lowered pH values after rainy season are thought of the results of flushing of oxidation products of pyrite accumulated during dry season in mine wastes. The results of two years later showed that pollution by AMD have progressed more seriously in that pH has been lowered by one order and metal contents increased about twice. The spatial distribution of various Fe, Al hydroxides and sulfates occurring as red and white precipitates also changed. Red precipitates occurred at stream bed in longer distance after two years and white precipitates occurred far down from the mine wastes where no precipitates had been observed 1995. And metal contents in sediments also increased up to more than ten times.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.524-530
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• 2016

Agricultural soils near or around industrial complexes can contain a certain amount of heavy metals that readily enter the food chain and negatively affect human health. Therefore, we conducted the study to investigate the distribution of selected heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), mercury (Hg), and zinc (Zn), in farm-land soils around fifteen industrial complexes in the southwestern provinces, Korea. The concentrations of heavy metals in the soil samples were determined by the pseudo-total aqua regia (3 HCl : $1HNO_3$) digestion procedure. The heavy metal concentrations in most soils examined did not exceed the levels of Soil Contamination Warning Standard (SCWS) for agricultural lands (Region 1) presented in Soil Environment Conservation Law (SECL) established by Ministry of Environment (MOE), Korea. However, only one sampling site showed higher As amount ($27.1mg\;kg^{-1}$) than the SCWS level of As ($25mg\;kg^{-1}$). Pollution index (PI) for heavy metals did not exceed 1.0. The PI values were significantly positively correlated (p < 0.01) with the heavy metal concentrations. In particular, the values of correlation coefficient between the Cd and Pb concentrations and the PI values were higher than those estimated from other combinations, and thus the amounts of Cd and Pb in the agricultural soils highly affected the PI values for the heavy metals.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.163-171
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• 1998

Continuously contacting with camshaft the face of Valve Lifter made of cast iron brings about abnormal wear such as unfairwear or earlywear because it is heavily loaded in the valve train systems as the engine gets more powered. This abnormal wear becomes a defet namely over-clearance when the valve is lifting so that the fuel gas imperfectly combusted by unsuitable open or close aaction of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major cause of air pollution and combustion chamber. The imperfectly combusted by unsuitable open or close action of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major causes of air pollution and decrease of the engine output. Consequently to prevent this wear this study was to develop the valve lifter which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened ceramics alloy which has high wear resistance. Having the excellent surface hardness with Hv1100-1200 the sintered body developed with superhardened alloy(WC) can endure the severe face loading in the valve train system. We experienced with various brazing alloys and obtained the excellent joining strength to the joint had 150MPa shear strength. Interface analysis and microstructure in a joint were examined through SEM & EDS Optical microscope. Also 2,500 hours high speed(3,000-4,000 rpm) and continuous (1step 12hr) engine dynamo testing was carried out to casting valve liter and ceramics-metal joint valve lifter so that the abnormal wears were compared and evaluated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4713-4716
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• 2014

Several methods that have been used to manage a degasing process in recent years, such as an injection method that uses aluminum molten metal powder and chemicals, and the input method that supplies argon and nitrogen, or chlorine gas using a gas blow-tube. On the other hand, these methods have some problems, and it is a difficult process to handle pollution due to the production of considerable toxic gases, such as chlorine and fluoride gas, irregular effects, and lowering work efficiency due to the excessive processing time. The problems that are most fatal are the production of considerable sludge due to a reaction of aluminum molten metal with chemicals, loss of metals, and the decreasing life of refractory materials. To solve these problems, this study developed a technology that is related to continuous casting of molten aluminum metal and monolithic degasing apparatus.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.559-564
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• 2011

Soil microbial functions are considered to be effective in assessing the severity of heavy metal pollution. Therefore, this study was carried out to examine the effect of heavy metals on nitrogen mineralization by measuring the releasing pattern of inorganic nitrogen ($NH_4^+$-N and $NO_3^-$-N) in a soil treated with heavy metals. A factorial combination of two heavy metals (Zn and Cd) treated with three concentrations (50, 100 and $150{\mu}mol\;g^{-1}$ soils) was used in a laboratory incubation. Nitrogen mineralization was determined at 3, 7, 14, 21, 28, 42 and 56 days after the treatments replicated four times. Soil sample free from heavy metals was served as the control. The amount of nitrogen mineralization from heavy metal treated soils was found to be decreased at an increasing rate during the first 21 days of incubation. However, as the incubation progressed, nitrogen mineralization was found to be decreased at decreasing rates. Furthermore, during this period, nitrogen mineralization in Cd treated soils was significantly lower ($P{\leq}0.05$) than that of the control. Soils treated with Cd at the concentration of $150{\mu}mol\;g^{-1}$ showed the lowest N mineralization throughout the incubation. Nitrogen mineralization in Zn treated soils ($50{\mu}mol\;g^{-1}$) was found to be higher than the other heavy metal treated soils. On the base of present findings, nitrogen mineralization of soil could be considered as a viable assessment of the degree of heavy metal pollution.

• Journal of Ecology and Environment
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• v.44 no.4
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• pp.212-221
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• 2020

Background: Rapid industrialization has caused various impacts on nature, including heavy metal pollution. However, the impacts of industrialization vary depending on the types of industrializing activity and surrounding environment. South Korea is a proper region because the rapid socio-economical changes have been occurred since the late nineteenth century. Therefore, in this study, we estimate the anthropogenic impacts on an ecosystem from a sediment core of Yonghwasil-mot, an irrigation reservoir on the western coast of Korea, in terms of heavy metal concentrations, nutrient influx, and pollen composition. Results: The sediment accumulation rate (SAR) determined by 210Pb geochronology showed two abrupt peaks in the 1930s and 1950s, presumably because of smelting activity and the Korean War, respectively. The following gradual increase in SAR may reflect the urbanization of recent decades. The average concentrations of arsenic (As), copper (Cu), and lead (Pb) during the twentieth century were > 48% compared to those before the nineteenth century, supporting the influence of smelting activity. However, at the beginning of the twenty-first century, the As, Cu, and Pb concentrations decreased by 19% compared to levels in the twentieth century, which is coincident with the closure of the smelter in 1989 and government policy banning leaded gasoline since 1993. The pollen assemblage and nutrient input records exhibit changes in vegetation cover and water level of the reservoir corresponding to anthropogenic deforestation and reforestation, as well as to land-use alteration. Conclusions: Our results show that the rapid socio-economic development since the twentieth century clearly affected the vegetation cover, land use, and metal pollutions.

• Journal of Environmental Science International
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• v.11 no.8
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• pp.801-810
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• 2002

The current paper describes the indoor/outdoor air quality in school environments through analyses of the heavy metal concentrations using Inductive Coupled Plasma(ICP). School environments in a heavy traffic area, two industrial areas, quasi-industrial area, and residential area were evaluated. The results were as follows: (1) The locations with the highest indoor and outdoor concentrations of heavy metals were the industrial areas followed by the heavy traffic area, residential area, and quasi-industrial area in a descending order of magnitude. Plus, the indoor heavy metal concentrations were higher then the outdoor ones. (2) The main heavy metal components were Zn, Al and Ca. Higher concentration levels were found indoors than outdoors. The heavy metal concentrations were also higher in the classrooms than in the corridor or outdoors. (3) The total heavy metal concentrations in the studied areas were highly dependent on the weather elements. including the relative humidity, mixing ratio, and wet-bulb depression. Accordingly, special ventilation systems are recommended to reduce air pollution in school environments.

• Journal of Environmental Health Sciences
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• v.14 no.2
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• pp.29-41
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• 1988

This study was performed to investigate the air pollution levels in Daegu area titrough measuring of contents of water, chlorophyll, water soluble sulfur and lead metal in the leaves of roadside trees and chemical properties of soil under the urban trees. The results can be summarized as follows 1. The range of water content was from 60.4% to 74.6%. The comparisons of chlorophyll, water soluble sulfur and water content were regression equation, chlorophyll=0.1981+ 0.0040 water content (July), water soluble sulfur=3,139-0.0416 water content (July). and correlation coefficient, r=0.561 and r=0.549 respectively 2. Average contents of chlorophyll, water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were chlorophyll 0.050, 0.072mg/cm$^2$, water soluble sulfur 0.244, 0.333%, and lead metal 12.25, 12.68ppm in Oct. and Jul. respectively. 3. Correlation between chlorophyll and contents of water soluble sulfur and lead metal in the leaves of roadside tree at sampling sites were water soluble sulfur r=-0.564, -0.613 and lead metal r=-0.693, -0.699 in October and July, respectively. 4. Correlation between chlorophyll and water content, water soluble sulfur and lead metal in the leaves of tree showed positive significance.

• Journal of Preventive Medicine and Public Health
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• v.13 no.1
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• pp.3-12
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• 1980

Certain heavy metals which may lead peoples to poisonous status are widely used in industry and their uses have been increasing along with rapid industrialization of this country. Such an increasement of metal uses aggravates the status of environmental pollution affecting foodstuffs which are the most important life supporting factor of animal and humanbeing. Concerning the safety measures to minimize food-borne transmission of such hazardous metals, surveillance is the backbone of them and probably more so with a potential problem such as intoxication. Theoretically, this surveillance should include the determination of levels of heavy metal toxicants in foods, the determination of food consumption patterns and typical total diet, and the estimation of total load of the metal contaminant from all sources of exposure including air, water, and occupational sources. In recent year, actually, such estimates on the total daily intake of some heavy metals from foods have been made in several developed countries and a wide variation of date by season, locality, and research method was recognized. Also in this country, this kind of research data is vitally needed to make up for the serious shortage or lack of references to estimate the total amount of heavy metal intake of the people. In this study, a modification model for estimation of the total daily intake of cadmium copper, nickel, zinc, and lead through foods was applied and concentrations of the above metals in crops cultivated in this country were measured with atomic absorption spectro photometer to get the following results. 1. Level of heavy metal concentration in crops Generally, the levels of such metals in essential crops such as rice, cucumber, radish. chinese cabbage, apple, pear, grape, and orange are similar or lower than those in Japan and other developed countries. By the way, a striking result on cadmium concentration was increasement of its concentration in rice from $0{\sim}0.035ppm$ in 1970 to 0.11ppm in this study. However, the value is still far below the. Japanese Permissible Lebel of 1.0ppm. 2. Estimation of total daily intake per capita from foods A new model for estimation was devised utilizing levels of metal concentration in foods, amount of food consumed, and other food factors. Based on the above method, the daily intake of cadmium was estimated to be $70.53{\mu}g/man/day$ in average which was as high as the Limit Value of ILO/WHO(up to $71.4{\mu}g/man/day$). Also, 3.89mg of Zinc, 1.65mg of cuppor, 0.32mg of lead were given as the total daily intake per capita by this research. 3. Efficacy of washing or skinning to decrease the amount of metals in crops After washing the crops sufficiently with commercial linear alkylate sulfonate, the concentration of heavy metals could be reduced to $50{\sim}80%$ showing decreasement rate of $20{\sim}50%$. Also, after skinning the fruits, decreasement rate of the heavy metal concentration shelved $0{\sim}50%$.

• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.312-318
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• 1998

The potentials of some Korean wild plants as a phytoremediator for cleaning heavy metal pollution were measured. Several plant species, Ambrosia trifida, Brassica juncea, Rumex crispus, and Abutilon theophrasti screened previously for phytoremediator were treated with cadmium and copper solution. In order to know the growth response to heavy metal stress, the plants were cultivated in hydroponic system containing heavy metals with different concentration. To know the effects of heavy metals on emergence and seedling growth, seeds of 4 species were sown in the pot and watered with heavy metal solution adjusted pH to 6.5, 5.5, and 4.5. A proposed species as potential phytoremediator, A. trifida, showed tolerance to $20{\mu}mol/L$ Cd and $80{\mu}mol/L$ Cu in nutrient solution without apparent growth reduction, and up to $100{\mu}mol/L$ Cd and $400{\mu}mol/L$ Cu without critical visual injury. Up to 311mg/kg of Cd and 369mg/kg were accumulated in dried aerial part in A. trifida. In contrast, A. theophrasti showed injury at $400{\mu}mol/L$ Cu. Significant differences were shown in Cu accumulation among the four species. A. trifida had much higher concentrations of Cd in the shoot, whereas R, crispus accumulated higher concentrations of Cd in the shoot. Testing plant species showed reduced emergence rate with heavy metal treatment. When pH was lowered, the emergence and seedling growth were affected severely with heavy metal. We can suggested that A. trifida was the most proper species for phytoremediation in heavy metal-polluted regions.