• Economic and Environmental Geology
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• v.33 no.3
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• pp.181-193
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• 2000

This study was undertaken to evaluate the drinking water quality based on physicochemical properties and chemical compositions of the supply water in the Daedeok Campus, and to verify the analytical reliabilities of ICP-MS and IC equipped in the Central Research Facilities at Chungnam National University , Korea. The supply water belongs to $Ca^{2+}-({HCO_3}^-+{SO_4}^{2-})$type, whereas the original water from the Daecheong lake belongs to $(Ca^{2+}-(Mg^{2+})-{HCO_3}^-$ type. Generally, temperature (14.1$^{\circ}C$), pH (6.95), Eh (0 mV), electrical conductivity (117${\mu}$S/cm) and TDS (86.975mg/l) of supply water were higher than those of original lake water . Results using WATEQ4F revealed that potentially toxic ions of the supply water might exist mainly as free metals ($M^{2+}$) and a small amount as ${CO_3}^{2-}$ and $OH^-$ complexes. Also, the water composition belongs to the kaolinite field. Calculated average enrichment indies of the supply water normalized to lake water for anions, mamor cations, toxic cations and total ions are 1.05 , 1.56, 13.05 and 1.17 , respectively. Those values of the ground water in the Daedeok Campus showed 1.71, 4.78, 5.71 and 2.49 , respectively. However , contents of all constituents of these water are within the drinking water standard. All samples were filtered before the chemical analysis. Pale yellow or yellowish brown colored materials of colloidal particles coated the filter paper to thickness of 0.02 to 0.2mm. these are mainly Fe-Cy-Zn compounds with traces of Ni and Pb, the net weights of which compounds range from 0.01to 3.20mg/l. Most elements did not show any conceivable filtering effect of Cu, Fe and Zn. Especially, mean concentration of total Fe decreased considerably from 168.52${\mu}g$/lto 42.58${\mu}g$/l by filtering .

• Journal of Soil and Groundwater Environment
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• v.19 no.1
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• pp.1-7
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• 2014

When processing the biomass by Hydrothermal carbonization (HTC), a slow pyrolysis process, it produces bio-gas, biooil, and biochar. Among these end products, biochar is known for isolating or storing carbon and being used as a soil amendment. In this study, the characteristics of biochar generated by HTC at $250^{\circ}C$ for 1 hour, 2 hours, 3 hours, and 20 hours with synthetic food wastes and wood wastes were analyzed for potential uses in soil contaminated with heavy metals. The yield of biochar (weight %) increased when the ratio of wood wastes increased and showed a decreasing tendency as reaction time increased. Elemental analysis of biochar based on various conditions showed a maximum of 70% carbon (C) content. The carbon content showed an increasing tendency with the increase of wood wastes. Iodine adsorption test was peformed to determine the optimum reaction condition, which was 15% wood waste for mixing ratio and 2 hours for reaction time. Using biochar generated at the optimum condition, its capability of adsorbing heavy metals (Cd, Cu, Pb, Zn, Ni) was evaluated. It was concluded that lead (Pb) was removed efficiently while zinc (Zn) and nickel (Ni) were hardly adsorbed by biochar.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.895-908
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• 2023

Disposal of waste containing heavy metals into the environment is a major threat to human health and can result in toxic or chronic poisoning in aquatic life. In the current study, metal-resistant Raoultella ornithinolytica was isolated from metal-contaminated samples collected from the Tanjaro River, located southwest of Sulaymaniyah, Iraq. R. ornithinolytica was identified by partial amplification of 16S rRNA. The uptake potency of heavy metals was assessed using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and indicated that R. ornithinolytica removed 67, 89, 63.4, 55.6, 56.5, 65, and 61.9% of Cd, Pb, Cr, Ni, Zn, Co, and Fe, respectively. These removal rates were influenced by temperature, pH, and contact time; at 35℃ and pH 5 with a change in the incubation time, the reduction rate improved from 89 to 95% for Pb, from 36.4 to 45% for Cu, and from 55.6 to 64% for Ni. Gene analysis indicated that R. ornithinolytica contained pbrT, chrB, nccA, iroN, and czcA genes, but the pcoD gene was absent. Energy-dispersive X-ray spectroscopy (EDS) images showed evidence of metal ion binding on the cell wall surface with different rates of binding. Transmission electron microscopy (TEM) detected different mechanisms for metal particle localization; cell surface adsorption was the main mechanism for Pb, Zn, and Co uptake, while Cd, Ni, and Fe were accumulated inside the cell. The current study describes, for the first time, the isolation of R. ornithinolytica from metal-contaminated water, which can be used as an eco-friendly biological expedient for the remediation and detoxification of metals from contaminated environments.

• Journal of Environmental Science International
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• v.13 no.5
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• pp.479-488
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• 2004

Five sediment cores from the tidal flat of artificial Lake Shihwa are analyzed in terms of sedimentology and geochemistry to evaluate the heavy metal contamination and redox condition of surficial sediment following the Shihwa seawall construction. The variability of concentrations of various elements depends on the depositional environment, and reflects the various redox conditions and sediment provenances. The amounts of Ti and Al and their ratio of Ti/ Al with respect to Li clearly indicate that there is an anthropogenic contribution to the surficial sediment. The high concentrations of heavy metals suggest an anthropogenic contribution at ST. 34 and ST. 22. Concentrations of most elements (Cr, Cu, Zn and Pb) are higher near the Shihwa-Banwol industrial complex than in the central part of Lake Shihwa. Concentrations of heavy metal in surficial sediment near the Shihwa-Banwol industrial complex are two to eight times higher than in the center of Lake Shihwa. Enrichment factors (EF), which are normalized by the unpolluted shale, suggests a significant metallic contamination near the Shihwa-Banwol industrial complex (SBIC). The redox condition is divided into two anoxic and mixed oxi $c_oxic zones based on the carbon:sulfur (C/S) ratios of organic matter and elemental relationships. Correlations among geochemical elements Mn, U and Mo are significantly different from site to site, and may therefore be an indicator of the spatial redox condition. Controlling factors for switching anoxic/oxic conditions are thought to be water depth and the differences in industrial effluent supply. The variations of the Cu/Mn ratio in the sediments confirms above mentioned spatial differences of a redox condition in part, and therefore shows a location-dependence redox condition in sediments at four other sites. The redox condition of the surficial sediment characteristics of the Shihwa Lake are controlled by its geographic location and water depth.th.

• Microbiology and Biotechnology Letters
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• v.10 no.3
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• pp.185-190
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• 1982

A strain of Streptomyces sp. (YS-40) which was able to produce penicillinase, was isolated from soil and the enzymatic characteristics of this enzyme were investigated. The crude enzyme was obtained with the fractionation by 80 % cold acetone. The optimal temperature and pH of this enzyme was 45$^{\circ}C$ and 5.0 respectively. The stable pH range of the enzyme was between pH 5.5 and 8.0 at 37$^{\circ}C$. By heat treatment at 6$0^{\circ}C$ and 8$0^{\circ}C$ for 10 min, the remained relative activities were about 50%, 30% respectively. The activity of the enzyme was inhibited by Cu$^{＋＋}$, $_Mn^{＋＋}$, Zn$^{＋＋}$ but Co$^{＋＋}$, Li$^{＋＋}$, $Ca^{＋＋}$, $Mg^{＋＋}$ $Ba^{＋＋}$ did not affect. Among 11 chemical reagents, ethylenedi aminetetra-acetic acid disodium salt (EDTA-2Na), sodium dodecyl sulfate (SDS) and sodium fluoride inhibited the enzyme activity.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.597-613
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• 1996

The tonnage of copper and tungsten produced at Dalseong mine by Taehan Tungsten Mining Company from 1961 to 1971 was 48,704 tons (M/T) of 4 wt.% Cu and 1,620 tons (S/T) of 70wt.% WO, but the mine was closed in 1974. Kyeongsan mine is a small abandoned cobalt mine with no data of production. To investigate the pollution level of the mine areas, soils, plants (Ohwi and Pampanini), stream waters and stream sediments were taken and Fe, Mn, Cu, Pb, Zn, Ni, Co, Cd and Cr were analysed by ICP. Soils are considerably contaminated by the heavy metals related to ore deposits, The heavy metal contents in plants vary with the species and parts of plants. Stream waters are anomalously high in heavy metals in the vicinity of the mines but the contents decrease downstream in the process of dilution and precipiation. However, heavy metal contents increase very high in stream sediments due to precipiation. To protect environmental damages caused by acid mine drainages wetlands must be constructed outside pits, and it is necessary to fill pits with waters, limestone chips and organic materials, which give reducing and alkaline condition to ores. Under the condition pyrite is protected from oxidation and aqueous iron sulphates precipitate to form stable secondary pyrite.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.99.1-99.1
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• 2012

The thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4 - 1.6 eV and a large absorption coefficient of ~104 $cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative aqueous chemical approach based on chemical bath deposition (CBD) method for large area deposition of CZTS thin films. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and some factors like triethanolamine, ammonia, temperature which strongly affect on the morphology of CZTS film.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.285-285
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• 2010

$Cu(In,Ga)Se_2$ (CIGS) 박막 태양전지 제조에는 동시증발법 (co-evaporation)으로 Cu, In, Ga, Se 각 원소의 증발을 세 단계로 제어하여 CIGS 박막을 증착하는 3-stage 방법이 널리 이용된다[1]. 3-stage 중 1st-stage에서는 In, Ga, Se 원소 만을 증발시켜 $(In,Ga)_2Se_3$ 전구체 (precursor) 박막을 성장시킨다. 고효율의 CIGS 태양전지를 위해서는 $(In,Ga)_2Se_3$ 전구체 증착의 공정 변수와 이에 따른 박막 특성의 이해가 중요하다. 본 연구에서는 Mo 박막이 증착된 소다석회유리 (soda lime glass) 기판에 동시증발장비를 이용하여 280 380 의 기판 온도에서 In, Ga, Se 물질을 증발시켜 $(In,Ga)_2Se_3$/Mo/glass 시료를 제작하였으며 XRD, SEM, EDS 등의 방법을 이용하여 특성을 분석하였다. XRD 분석 결과 기판 온도 $280{\sim}330^{\circ}C$에서는 $(In,Ga)_2Se_3$ 박막의 (006), (300) 피크가 관찰되었으며, 기판 온도가 증가할수록 (006) 피크 세기는 감소하였고 (300) 피크 세기는 증가하였다. $380^{\circ}C$에서는 (110)을 포함한 다수의 피크가 관찰되었다. 그레인 (grain) 크기는 기판 온도가 증가할수록 커지며 Ga/(In+Ga) 조성비는 기판 온도에 따라 일정함을 각각 SEM과 EDS 측정을 통해 알 수 있었다. $(In,Ga)_2Se_3$ 전구체의 (300) 배향은 CIGS 박막의 (220/204) 배향을 촉진하고[2], 이것은 높은 광전변환효율에 기여하는 것으로 알려져 있다. 때문에 $(In,Ga)_2Se_3$의 (300) 피크의 세기가 가장 큰 조건인 $330^{\circ}C$를 1st-stage 증착 온도로 하여 3-stage CIGS 태양전지 공정을 수행하였으며, $MgF_2$/Al/Ni/ITO/i-ZnO/CdS/CIGS/Mo/glass 구조의 셀에서 광전변환효율 16.96%를 얻었다.

• Journal of Life Science
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• v.25 no.5
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• pp.577-584
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• 2015

Orostachys malacophyllus grow on the old roofing tile or on the rock of mountain and is belong to Crassulaceae family. After air drying for Orostachys malacophyllus (OM), using the mixture of lactic acid bacteria (Lactobacillus bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus) was fermented (FOM). OM and FOM extracted using water (W), ethanol (E) and methanol (M) and were measured extracts yield, pH and Brix. Extracted OM and FOM were tested by in vitro experimental models of α,α´-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging activity, Fe/Cu reducing power, linoleic acid peroxidation using ferric thiocyanate and thiobarbituric acid (TBA) methods and peroxidation of rat liver homogenate. In addition, the bioactive materials (phenolic compounds, flavonoids and minerals) were measured. The highest phenolic compounds and flavonoids were OME 122.2 mg/100 g and OME 84.0 mg/100 g. OM and FOM′s major minerals were K, Ca and Mg. The highest free radical scavenging activity showed in FOMM (93.9%), OMM (93.4%), FOME (92.1%) and OME (91.9%) at 0.5% additional level. Fe reducing powers were strong in FOME and FOMM and Cu reducing powers were strong in OME and FOMM. Antioxidant activities on lipid peroxidation using rat homogenate as measured by TBARS method showed strong in FOME and on lipid peroxidation of linoleic acid as measured by ferric TBA method showed strong in OME and FOME and measured by ferric thiocyanate showed strong in FOME and FOMM.

• Economic and Environmental Geology
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• v.30 no.6
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• pp.553-566
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• 1997

Origin, behavior and enrichment of environmental toxic elements from the Deokpyeong area were investigated on the basis of major, trace and rare earth element geochemistry. Coaly metapelites of the Deokpyeong area are subdivided into grey phyllite, dark grey phyllite, coaly slate and black slate, which are interbedded along the Ogcheon Supergroup. The coaly slate had been mined for coal, but mining is closed. The coaly and black slates are lower contents of $SiO_2$ and $Al_2O_3$, and higher contents of LOI, CaO, $Na_2O$ and BaO as compared with the phyllitic rocks. Rare earth elements are highly enriched in the coaly and black slate. Average compositions (ppm) of minor and/or environmental toxic elements in the coaly and black slate are revealed as As=127, Ba=30,163, Cd=18, Cr=740, Cu=84, Mo=378, Pb=43, Sb=12, Se=44, U=144, V=8,147 and Zn=292, which are extremely high concentrations than those in the NASC compositions. Major elements (average enrichment index; 5.34) in the coaly metapelites are mostly depleted, excepting $P_2O_5$ and BaO, normalized by NASC. Rare earth elements (average enrichment index; 1.48) are enriched in the coaly slate. On the basis of NASC, minor and/or environmental toxic elements in the coaly metapelites were strongly enriched of all the elements with the exception of Co, Cs, Ni and Sr. Average enrichment index of trace elements in coaly metapelite is 31.51 (coaly slate; 51.94 and black slate; 15.46). Especially, enrichment index of potentially toxic elements (As, Ba, Cr, Cu, Mo, Ni, Sb, Se, U, V and Zn) of the rock is 46.10 (grey phyllite; 7.15, dark grey phyllite; 4.77, coaly slate; 88.96 and black slate; 22.11). These coal formations were deposited in basin of boundary between terrestrial and marine environments deduced to carbon, sulfur (C/S=2.2 to 275.7), trace and rare earth elements characteristics. Irregular behavior and dispersion between major, minor and rare earth elements of those metapelites indicates a variable source materials, incomplete mixing of differential source and/or reequilibrium of diagenesis and metamorphism.