• The Plant Pathology Journal
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• 제28권4호
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• pp.446-452
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• 2012

The effect of heavy metals on seedling growth and pigment levels was studied in Arabidopsis using essential (Cu, Mn, and Zn) and non-essential metals (Pb and Hg). Generally increasing the concentrations of the metals resulted in a gradual decrease in root and shoot lengths, a decrease in chlorophylls, an increase in anthocyanins and a fluctuation in carotenoid content depending on the metal types. The toxicity of the metals decreased in the following order: Cu > Hg > Pb > Zn > Mn. Among the five metals, Cu was exceptionally toxic and the most potent inducer of anthocyanins. Pb induced the smallest quantity of anthocyanins but it was the strongest inducer of carotenoids. It suggests that the Cu-stressed Arabidopsis may use anthocyanins as its main antioxidants while the Pb-stressed Arabidopsis use carotenoids as its main protectants. All of the five metals induced an accumulation of anthocyanins. The consistent increase in anthocyanin content in the metal-stressed Arabidpsis indicates that anthocyanins play a major role in the protection against metal stresses.

• Environmental Engineering Research
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• 제11권6호
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• pp.303-310
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• 2006

The aim of this study is to assess the applicability of sericite in wastewater treatment particularly the removal of two important heavy metal toxic ions viz., Cu(II) and Pb(II) from aqueous solutions. The batch type experiments showed that sericite is found to be one of useful natural sorbent for the removal of these two cations from aqueous solutions and it is also to be observed that with the increase in sorptive concentration amount of metal uptake increases and the concentration dependence data obtained are fitted well for the Langmuir adsorption isotherm rather than Freundlich adsorption model. Further, the Langmuir monolayer adsorption capacity is found to be $1.674\;mg\;g^{-1}$ for Cu(II) and $4.697\;mg\;g^{-1}$ for Pb(II). Kinetic studies enabled, an apparent equilibria can be achieved between soild/solution interface within ca 10 mins for Cu(II) and ca 90 mins for Pb(II). Moreover, the removal behavior of sericite for these two metal ions is greatly influenced by solution pH.

• Environmental Engineering Research
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• 제18권4호
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• pp.221-227
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• 2013

A risk assessment of environmental media was performed for the inhabitants in the area of the abandoned Nokdong metal mine. Soil, groundwater, and crop samples were collected from September to October 2008 around the mine. After pretreatment of these samples, metal concentrations were measured, and a risk assessment was performed using the Korean soil-contamination risk assessment guidelines. Lead (Pb) and arsenic (As) intake rates were the highest for inhalation of soil dust. The cancer risks from ingestion of As-contaminated groundwater, inhalation of As-, Cd-, and Pb-contaminated soils, and contact of As-contaminated soils exceeded the acceptable risk. The sum of all carcinogenic risks was $9.29{\times}10^{-3}$. The non-carcinogenic risk was highest for ingestion of As-contaminated water (11.0), followed, in descending order, by inhalation of Hg-contaminated soil and ingestion of Pb-contaminated water. Most of the risks were associated with As, Cd, Pb, and Hg contamination, and therefore, these metals were considered to be potential toxic carcinogens and non-carcinogens for humans in this area. In this study, the non-carcinogenic risks of ingestion of contaminated water or crops, as well as those associated with the inhalation of soil dust were observed.

• 한국광물학회지
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• 제23권2호
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• pp.161-170
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• 2010

많은 미생물들이 수용성 망간이온($Mn^{2+}$)을 불용성인 산화망간($Mn^{4+}$) 광물로 산화 침전시키는데, 이와 같은 생물학적 산화반응은 비생물학적 산화반응보다 훨씬 빠르게 일어난다. 이처럼 미생물에 의해 생성된 바이오 산화망간 광물은 표면의 강한 흡착성과 산화환원 반응을 통해 생지구화학 순환과 환경오염물질의 생물흡수도에 큰 역할을 한다. 본 논평은 양자역학의 밀도범함수 이론에 바탕을 둔 전산모사를 이용하여 산화망간 광물 표면의 독성금속 흡착의 자세한 기작과 망간원자 빈자리의 광화학적 역할을 새롭게 밝힌 최근 연구결과를 소개한다.

• Advances in environmental research
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• 제3권4호
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• pp.283-292
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• 2014

Iron precipitating organisms play a significant role in the formation of ferric hydroxide precipitate, which acts as strong adsorbent for toxic metal. In this respect four different iron precipitating cultures were isolated from Hutti gold mine surface winze water sample on citrate agar medium. The best isolate was screened out for metal removal study on the basis of fast visual iron precipitation. The selected isolate was identified as Enterobacter sp. based on routine biochemical tests and Biolog GN microplate results and as Enterobacter cloacae subsp. dissolvens by 16S rRNA gene sequence analysis (GenBank accession number EU429448). Influence of medium composition, medium initial pH, the influence of inoculum size, effect of various media and ferric ammonium citrate concentration were studied on metal removal in shake flask experiments. Under the optimized conditions studied, E. cloacae showed $94{\pm}2$, $95{\pm}2$ and $70{\pm}2%$ of cadmium, copper and mercury removal from a simulated waste in shake flask studies. In lab scale column reactor more than 85% of copper and mercury removal was achieved.

• 한국안전학회지
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• 제20권4호
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• pp.40-45
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• 2005

The principal actions of a flame retardant are to decrease or prevent the formation of volatile products and increase the formation of char layer. Use of flame retardant additives can decrease the overall fire hazard of the product containing them thus leading to an increase in overall fire safety. Although several flame retardants have been developed for use in polymers, many of these are known to increase the amount of smoke and toxic gases generated by them. This paper present a new flame retardant using metal addition flame retardant. For this study, the experiments of flame retardancy conducted are as follows : burning ratio, weight loss rate using TGA-DTA, the measurement of LOI and char yield. And smoke mass concentration and CO yield were measured. The metal addition flame retardant reduced burning ratio and weight loss rate, increased the LOI and yield of char formation with decreased smoke mass concentration and CO yield.

• Journal of Industrial and Engineering Chemistry
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• 제67권
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• pp.28-51
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• 2018

Graphitic carbon nitride ($g-C_3N_4$) as a fascinating visible light active semiconductor photocatalyst has medium band gap, non-toxic nature, stable chemical structure and high thermal stability. Recently, intensive researches are focused on photocatalytic activity of $g-C_3N_4$ for wastewater treatment. This review demonstrates latest progress in fabrication of graphitic carbon nitride $C_3N_4$ incorporated nanocomposite to explore photocatalytic ability for water purification. The $g-C_3N_4$-based nanocomposites were categorized as $g-C_3N_4$ metal-free nanocomposite, noble metals/$g-C_3N_4$ heterojunction, non-metal doped $g-C_3N_4$, transition and post transition metal based $g-C_3N_4$ nanocomposite. Apart from fabrication methods, we emphasized on elaborating the mechanism of activity enhancement during photocatalytic process.

• 한국해양학회지
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• 제10권1호
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• pp.33-40
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• 1975

본 연구의 결과를 간단히 요약하면 다음과 같다. 가. KCl수용액에서의 Dowex 1-X8, Cl$^{-}$(200-400메쉬)에 의한 Hg(II), Cd(II) 및 Zn(II)의 흡착메카니즘은 고농도의 KCl수용액에서는 모두 음이온의 MCl$_{4}$ $^{2-}$ 착이온 형성에 의한 흡착이며, 저농도에서는 착이온 안정도상수가 큰 Hg(II) 는 역시 착이온 형성에 의한 흡착인데 비해 Cd(II)와 Zn(II)의 경우는 농도에 따라 다르다. 한편 D값의 크기순위는 HCl메디움에서의 MCl$_{4}$$^{2-}$ 착이온의 안정도 상수의 크기순위와 일치한다. 나. KCl-Methonol메디움에서의 Dowex 1-X8, Cl$^{-}$수지에 대한 금속이온의 흡착은 메탄올의 농도증가에 따라 증가되는데, 이것은 메탄올 첨가로 인해 수화현상이 약화되어 착이온 형성이 용이해지기 때문이며 착이온을 잘 형성하는 Hg(II)의 경우는 그 증가율이 크지 않았다. 다. 양이온교환 수지 Dowex50W-X$_{8}$ , $K^{+}$column내에서 KCl-H$_{2}$O 및 KCl-MeOH 용리액에 의한 Zn(II), Cd(II) 및 Hg(II)의 융리메카니즘은 역시 금속이온의 MCl$_{4}$$^{2-}$ 착이온 형성 및 이온쌍 형성의 차이로 용리되는데 그 부피분배 계수의 크기는 Zn(II)>Cd(II)>Hg(II)이며, MeOH의 농도가 증가하면 더욱 빨리 용리되는데 이는 역시 MeOH첨가에 인한 착이온 및 이온쌍 형성이 증대되기 때문이다. 라. MCl(M:K$^{+}$, $Na^{+}$, NH$_{4}$$^{+}$ 및 H$^{+}$) 수용액 메디움에서의 Cd(II), Mg(II) 및 Zn(II)의 Dowex 1-X8, Cl$^{-}$ 수지에 대한 흡착은 역시 어떤 메디움에서도 Cd(II) 흡착이 제일 크며, 다음이 Zn(II) 이고 착이온을 형성않는 Mg(II)이 제일 작았다. 한편 메디움 종류별 D값의 크기순위는 H$^{+}$>K$^{+}$> $Na^{+}$>NH$_{4}$$^{+}$이였다. 메디움의 종류에 따라 D값의 차이가 나는 것은 금속이온의 착이온 형성과 금속이온의 용액내에서의 이온종의 상태와 관련이 있다고 생각된다. 마. MCl(M:K$^{+}$, $Na^{+}$, NH$_{4}$$^{+}$ 및 H$^{+}$)과 MNO$_{3}$ 용리액에 의한 Cd(II), Mg(II) 및 Zn(II)의 용리는 예상한 바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구의 목적중의 하나인 인체유해 중금속이온인 Hg(II), Cd(II)등이 NaCl같은 염화물이 함유된 시료용액에 공해이온으로 존재할 경우 흡착에 의한 제거가 가능하다. 한편 이같은 중금속이온의 흡착실험은 특히 해수중의 금속이온의 회수연구에도 그 활용이 가능하리라고 믿는다.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2737-2740
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• 2012

The use of plants to remove toxic metals from soil (phytoremediation) is emerging as a cost-effective alternative to conventional methods for the removal of heavy metals from contaminated soil. Indian mustard (Brassica juncea) was used as the plant to accumulate high tissue concentrations of lead when grown in contaminated soil. For this study, the application of an electric field combined effectively with EDTA-enhanced phytoremediation. A stimulation of direct and alternating electric potential was compared and EDTA-enhanced phytoremediation of lead using Indian mustard has been performed. The effects of experimental parameters such as operating voltage with different concentration of EDTA, the number of graphite electrodes, and cultivation period on the removal of toxic metal were studied. Shoot lead accumulations in Indian mustard increased as the concentration of EDTA and dc electric potential was increased. Two to four folds was increased when EDTA plus a dc electric potential was applied, compared to an ac electric potential. The maximum lead accumulation in the shoots was achieved by applying EDTA plus dc electric potential with 6 graphite electrodes.

• Toxicological Research
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• 제27권3호
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• pp.143-147
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• 2011

Cadmium is considered one of the most toxic, non biodegradable heavy metal for the human and animals. The purpose of the present study was to investigate the changes in biochemical parameters of blood and accumulation of cadmium in various tissue caused by various levels of dietary cadmium chloride ($CdCl_2$) in broiler chicks. $CdCl_2$ was administered through drinking water to broiler chicks. In spectral analysis, $CdCl_2$ treatment caused a significant increase in Glutamate pyruvate transaminase (GPT), creatinine and uric acid levels in all treated groups. Intriguingly, the GPT, creatinine, and uric acid levels were significantly higher at 75 mg/kg as compared to the groups treated with high doses (100, 125 and 150 mg/kg) of $CdCl_2$. Atomic Absorption Spectrophotometer (AAS) was used for the determination of Cd accumulation in kidney, liver and Breast muscles. AAS analysis revealed that Cd accumulation is increased in breast muscles as compared to liver and kidney at higher doses of Cd than 75 mg/kg.