• Economic and Environmental Geology
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• 제37권1호
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• pp.73-86
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• 2004

In order to estimate the post-ingestion bioavailability of heavy metals and to assess the risk of adverse health effects on human exposure to toxic heavy metals, environmental geochemical surveys were undertaken around the Dogok Au-Ag-Cu and the Hwacheon Au-Ag-Pb-Zn mine sites. Human risk assessment of toxic heavy metals was performed with the results of the SBET(simple bioavailability extraction test) analysis for soil and chemical analytical data for crop plant and water. Arsenic and other heavy metals were highly elevated in tailings from the Dogok(218 As mg/kg, 90.2 Cd mg/kg, 3,053 Cu mg/kg, 9,473 Pb mg/kg, 14,500 Zn mg/kg) and the Hwacheon(72 As mg/kg, 12.4 Cd mg/kg. 578 Pb mg/kg, 1,304 Zn mg/kg) mines. These significant concentrations can impact on soils and waters around the tailing dumps. The quantities of As, Cd and Zn extracted from paddy soils in the Hwacheon mine using the SBET analysis were 55.4%, 20.8% and 26.4% bioavailability, respectively, and for farmland soils in the Dogok mine, 40.8%, 37.6% and 33.0% bioavailability, respectively. From the results of human risk assessment, HI(Hazard Index) value exceeded 1.0 for As in the Hwacheon mine and for Cd in the Dogok mine. Thus, toxic risks for As and Cd exist via exposure(ingestion) of contaminated soil, water and rice grain in these mine sites. The cancer risk for As by the consumption of rice and groundwater in the Hwacheon mine area was 8E-4 and 1E-4, respectively. This risk level exceeds the acceptable risk(1 in 100,000) for regulatory purpose. Therefore, regular ingestion of locally grown rice and ground-water by the local population can pose a potential health threat due to long-term arsenic exposure.

• Economic and Environmental Geology
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• 제51권5호
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• pp.401-407
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• 2018

For the treatment of heavy metals in the mine drainage from the closed mine area, various methods such as passive, active and semi-active treatments are considered. Among contaminated elements in the mine drainage, Mn is one of the difficult elements for the treatment because it needs high pH over 9.0 for its concentration to be reduced. In this study, the efficiency of various slag complex reactors (slag (S), slag+limestone (SL) and slag+Mn coated gravel (SG)) on Mn removal in the presence of Fe, which is a competitive element with Mn, was evaluated to investigate effective methods for the treatment of Mn in mine drainage. As a result of experiments on Mn removal without Fe during 358 days, using influent with $30{\sim}50Mn{\cdot}mg/L$ and pH 6.7 on the average, S reactor showed continuously high Mn removal efficiency with the average of 99.9% with pH 8.9~11.4. Using the same reactors, Mn removal experiments with Fe during 237 days were conducted with the influent with $40{\sim}60Mn{\cdot}mg/L$. The pH range of effluent reached to 6.1~10.0, which is slightly lower than that of effluent without Fe. S reactor showed the highest range of pH with 7.1~9.9, followed by S+L and S+G reactor. However, the efficiency of Mn removal showed S+L>S>S+G with the range of 94~100%, 68~100% and 68~100%, respectively in spite of relatively low pH range. S+L reactor showed the most resistance on Fe input, which means other mechanisms such as $MnCO_3$ formation by the carbonate prouced from the limestone or autocatalysis reaction of Mn contributed to Mn removal rather than pH related mechanisms. The evidence of reactions between carbonates and Mn, rhodochrosite ($MnCO_3$), was found from the X-ray diffraction analysis of precipitates sample from S+L reactor. From this study, the most effective reactors on Mn removal in the presence of Fe was S+L reactor. The results are expected to be applied for the Mn containing mine water treatment in the presence of Fe within the relatively low range of pH.

• Journal of Korean Society of Environmental Engineers
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• 제28권4호
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• pp.438-446
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• 2006

A lab-scale batch test was conducted to develop capping materials to reduce the sediment phosphorus in the stagnant water zone of Gyeongancheon in Paldang Lake. The mean grain size(Mz) of sediment in the investigated area was 7.7 ${\phi}$, which is very fine, and the contents of organic carbon($C_{org}$) was 2.4%, which is very high. For the phosphorous release experiment to select the optimal capping material, sand layer, powder-gypsum($CaSO_4{\cdot}2H_2O$), granule-gypsum, complex layer(gypsum+sand) and the control were compared and evaluated in the 150 L reactor for 45 days. In case of the capping with the sand, it was found that the phosphorous from the sediment could be reduced by around 50%. However, it was found that this caused the reduction of the dissolved oxygen in the water column(by less than 3 mg/L) due to the resuspension of sediment and the organic matter decomposition that comes from the generation of $CH_4$ gas in the 1 cm of the sand layer. Therefore, it is likely that the sand layer has to be thickener in case of the sand capping. Powder-gypsum and granule-Gypsum reduced phosphorous release by more than 80%. However, the concentration of ${SO_4}^{2-}$ in the water column increased, making it difficult to apply it to the drinking water protection zone. We developed Fe-Gypsum and $SiO_2$-gypsum materials to reduce the solubility of ${SO_4}^{2-}$. Powder-Gypsum creates the interception film that does not have any aperture on the sediment layer when it is combined with the water. However phosphorous release caused by the generation of $CH_4$ gas may happen at a time when the gypsum layer has the crack. Capping through the complex layer(granule-Gypsum+sand(1 cm)) found to be suitable for the drinking water protection zone because it was effective to prevent phosphorus release. Moreover, this leads to the lower solubility from the concentration of ${SO_4}^{2-}$ into the water column than the powder-Gypsum and granule-Gypsum. The addition of gypsum($CaSO_4{\cdot}2H_2O$) into the sediment can reduce the progress of methanogensis because fast early diagenesis and sufficient supply of ${SO_4}^{2-}$ to the sediment, stimulate the SRB(sulfate reducing bacteria) highly.

• Korean Journal of Environmental Agriculture
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• 제12권2호
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• pp.129-143
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• 1993

The objective of this study is to understand the status of the water pollution in rural areas and to furnish a basic material for the management of the water pollution in rural areas. For this purpose, the Bokha river basin, Ichon-Gun, Kyungki-Do considering as a typical agricultural area was selected as a representative experimental watershed. The characteristics of water pollution in streams of the Bokha river basin was revealed by investigating and analyzing data collected for the source of pollution, water qualities in reaches of the stream, the degree of contribution to the river contamination by pollution mass produced from each source, and the status of the self-purification at the main stream. The most important source of the water pollution in investigated watershed was livestock, and the next important one were in the order of population, land use, and industry. The water quality of the Bokha river was relatively favorable judging from the BOD and COD concentration, however since the concentration of T-N and T-P showed significantly large values, it was concluded that the river was seriously contaminated by the nutrient material. The main cause of the river contamination was proved due to livestock waste. For the T-N, both land use and livestock were much more contributied to the pollution than any other source, which characterized the typical water pollution of rural areas. Run-off ratios for the Bokha river tributaries to the main stream were changed according to the similar trend to the variation of discharges in the branch streams. For the value of the self-purification constant at the main stream, it showed smaller value in the downstream reach than the middle-stream and upstream reaches, where could possibly have smaller reoxidation action due to slower velocity and deeper water depth.

• Korean Journal of Food Science and Technology
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• 제46권1호
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• pp.108-114
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• 2014

To analyze the hazards associated with cucumber and hot pepper cultivation areas, a total of 72 samples were obtained and tested to detect the presence of biological (sanitary indicative, pathogenic bacteria and fungi) and chemical hazards (heavy metals and pesticide residues). The levels of sanitary indicative bacteria (aerobic plate counts and coliforms) and fungi were ND-7.2 and ND-4.8 log CFU/(g, mL, hand, or $100cm^2$) in cucumber cultivation areas, and ND-6.8 and 0.4-5.3 log CFU/(g, mL, hand, or $100cm^2$) in hot pepper cultivation areas. More specifically, the soil of hot pepper cultivation areas was contaminated with coliforms at a maximum level of 5.6 log CFU/g. Staphylococcus aureus was detected only in glove samples at a level of 1.4 log CFU/$100cm^2$ and Bacillus cereus was detected in the majority of samples at a level of ND-4.8 log CFU/(g, mL, hand, or $100cm^2$). Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella spp. were not detected. Heavy metal (Zn, Cu, Ni, Pb, and Hg) chemical hazards were detected at levels lower than the regulation limit. Residual insecticides were not detected in cucumbers; however, hexaconazole was detected at a level of 0.016 mg/kg (maximum residue limit: 0.3 mg/kg) in hot peppers.

• Korean Journal of Soil Science and Fertilizer
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• 제40권4호
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• pp.298-310
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• 2007

This study compared the correlation between the accumulated copper content in earthworms and the copper concentration rate of soil measured using several methods to extract heavy metals from soil. For the experiment, a microcosm soil test was carried out using copper contaminated soil from the vicinity of copper-roofed buildings and earthworms (Eisenia fetida). Soils from the study area were used to produce 6 treatments; control, 1C (contamination level with the lowest treated copper concentration rate), 2C, 4C, 8C, and 16C (contamination level with the highest treated copper concentration rate). Microcosm soil test using the 6 treatments proved that as the copper content in soil and the experiment time increased, the growth rate of and the accumulated copper concentration rate in earthworms increased as well. The degree of the increase corresponded to the order of the treated copper concentration levels in microcosm soils. Standard method of the ministry of environment and EPA method 3051 were used to obtain the copper concentration in soil and the total copper content in soil, respectively. The correlation coefficient (r) of 0.9875~0.9993 between the copper content extracted by the standard method and the total copper content shows high positive correlation. The correlation coefficient of the copper content in soil extracted by the standard method and the accumulated copper content in earthworms, and the correlation coefficient of the total copper content in soil and the accumulated copper content in earthworms were ranged from 0.9193 to 0.9728 and from 0.9282 to 0.9844, respectively, showing highly significant positive correlation. Due to the high correlation between the copper concentration in soil and the accumulated copper content in earthworms, it is concluded that earthworms are suitable to be used as biological indicator species or for bio-monitoring against copper contamination of soil.

• Journal of Food Hygiene and Safety
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• 제19권2호
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• pp.60-65
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• 2004

120 samples of ready-to-eat salad product were purchased at department stores, marts and family restaurants in metro area. Coliform bacteria and food borne pathogenic bacteria were isolated from these samples. In 73 samples among the 120 salad product samples, coliform bacteria and food borne pathogenic bacteria were detected by 60.8％ of isolated rate. Salad were classified into organic and non-organic salad. According to a salad type, salad were classified into vegetable salad and mixed vegetable salad with fried chicken and extra food. According to a packing type, packed salad product and salad-bar product were classified. After the classification, the results of each cases were compared. There is no statistical relation between cultivation or packing methods and contaminated bacteria. But the incidence number of microbial strains was significantly different between vegetable salad and mixed vegetable salad(p＜0.005). In vegetable salad, more various strains were detected. E. coli was isolated in 10 cases among the 90 cases in non-organic vegetable and in 7 cases among the 30 cases in organic salad. Food borne pathogenic bacteria were isolated in non-organic vegetable salad product. Staphylococcus aureus was isolated in 4 cases of vegetable salad product and Salmonella spp. isolated in 1 case. After 5 times examination of each 4 market products, the total number of aerobic bacteria was average 4.8$\pm$0.19 log cfu/g. One sample from this product, saline and a detergent for vegetable were used for 3 minutes to notice the effect. As a result, when saline was used 5 times and detergent for vegetable was used 1 time, bacterial contamination was decreased up to 95.5％.

• The Korean Journal of Mycology
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• 제36권2호
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• pp.163-171
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• 2008

We have surveyed the variation of physical and chemical characteristics of aerobic and anaerobic outdoor fermentation of cotton wastes using for oyster mushroom cultivation. The inner temperature of cotton wastes fermented aerobically covered with thin cloth and setting pallet at bottom was higher than that of anaerobic fermented cotton wastes covered with P.E vinyl and the maximum temperature was $75^{\circ}C$ at 5th day after fermentation. pH of cotton wastes fermented aerobically was increased up to 8.9 after fermentation of $9{\sim}12$ days, but that of anaerobically fermented was decreased up to 5.0. Total carbon content was decreased but total nitrogen content was increased when fermentation was in progress. Oxygen concentration of cotton wastes fermented aerobically was decreased until 6 days after fermentation but increased after 9 days of fermentation. Ammonia concentration of cotton wastes fermented aerobically and anaerobically was below 10 ppm and $20{\sim}85\;ppm$ respectively. In anaerobic condition the cotton wastes was contaminated with mold ($15{\sim}50%$), where no contamination was found in aerobic condition during spawn running stage. Yields of mushroom grown on cotton wastes aerobically fermented for $6{\sim}9$ days was $23.0{\sim}23.6\;kg$ per $3.3\;m^2$ area.

• Economic and Environmental Geology
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• 제37권5호
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• pp.569-583
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• 2004

The rock properties of the West pagoda in the Gameunsaji temple site are composed mainly of dark grey porphyritic granodiorite with medium grained equigranular texture and developed with small numerous dioritic xenoliths. These xenoliths occurred with small holes due to different weathering processes. As a weathering results, the rock properties of this pagoda occur wholly softened to physical hardness because of a complex result of petrological, meteorological and biological causes. Southeastern part of the pagoda deteriorated seriously that the surface of rock blocks showed partially exfoliations, fractures, open cavities in course of granular decomposition of minerals, sea water spray and crystallization of salt from the eastern coast. The Joint between blocks has small or large fracture cross each other, contaminated and corrupted for inserting with concrete, cement mortar, rock fragments and iron plates, and partially accelerated coloration and fractures. There are serious contamination materials of algae, fungus, lichen and bryophytes on the margin and the surface on the roof stone of the pagoda, so it'll require conservation treatment biochemically for releasing vegetation inhabiting on the surface and the discontinuous plane of the blocks because of adding the weathering activity of stones and growing weeds naturally by soil processing on the fissure zone. Consisting rock for the conservation and restoration of the pagoda would be careful choice of new rock properties and epoxy to reinforce for the deterioration surfaces. For the attenuation of secondary contamination and surface humidity, the possible conservation treatments are needed.

• Journal of Soil and Groundwater Environment
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• 제7권4호
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• pp.68-76
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• 2002

In this study, we have investigated the geochemical behavior and fate of heavy metals in acid rock drainage (ARD). The ARD was collected from the area of the former Dongrae pyrophyllite mine. The Dongrae Creek waters were strongly acidic (pH : 2.3~4.2) and contained high concentrations of $SO_4$, Al, Fe, Mn, Pb, Cu, Zn, and Cd, due to the influence of ARD generated from weathering of pyrite-rich pyrophyllite ores. However, the water quality gradually improved as the water flows downstream. In view of the change of mole fractions of dissolved Fe, Al and Mn, the generated ARD was initially both Fe- and AA-ich but progressively evolved to more Al-rich toward the confluence with the uncontaminated Suyoung River. As the AR3 (pH 2.3) mixed with the uncontaminated waters (pH 6.5), the pH increased up to 4.2, which caused precipitation of $SO_4$-rich Fe hydroxysulfate as a red-colored, massive ferricrete precipitate throughout the Dongrae Creek. Accompanying the precipitation of ferricrete, the Dongrae Creek water progressively changed to more Al-rich toward downstream sites. At the mouth of the Dongrae Creek, it (pH 3.4) mixed with the Suyoung River (pH 6.9), where pH increased to 5.7, causing precipitation of Al hydroxysulfate (white precipitates). Neutralization of the ARD-contaminated waters in the laboratory caused the successive formation of Fe precipitates at pH<3.5 and Al precipitates at higher pH (4~6). Manganese compounds were precipitated at pH>6. The removal of trace metals was dependent on the precipitation of these compounds, which acted as sorbents. The pHs for 50% sorption ($pH_{50}$) in Fe-rich and Al-rich waters were respectively 3.2 and 4.5 for Pb, 4.5 and 5.8 for Cu, 5.2 and 7.4 for Cd, and 5.8 and 7.0 for Zn. This indicates that the trace metals were sorbed preferentially with increasing pH in the general order of Pb, Cu, Cd, and Zn and that the sorption of trace metals in Al-rich water occurred at higher pH than those in Fe-rich water. The results of this study demonstrated that the partitioning of trace metals in ARD is not only a function of pH, but also depends on the chemical composition of the water.