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The Experimental Measurements of Total Mass Attenuation Coefficients in Arsenic Oxide
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作者 B. Vasundhara P. Tejeswararao 《World Journal of Nuclear Science and Technology》 2016年第3期125-130,共7页
Measurements of K-shell mass attenuation coefficients are reported for the first time in Arsenic oxide (As<sub>2</sub>O<sub>3</sub>). Experiments are performed using Arsenic Oxide extended rang... Measurements of K-shell mass attenuation coefficients are reported for the first time in Arsenic oxide (As<sub>2</sub>O<sub>3</sub>). Experiments are performed using Arsenic Oxide extended range HPGe detector. To achieve measurements at many small and regular energy intervals, secondary X-ray emission technique using “Seventeen Scatters” is employed. The results are in agreement with the proposed theoretical estimates. No evidence could, however be gained in favor of microscopic theories such as RRS and EXAFS, insofar as there are no energy points within a range of 100eV on either side of the K-edge. 展开更多
关键词 Mass Attenuation arsenic oxide K-SHELL Energy Intervals
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Solar Oxidation and Removal of Arsenic from Groundwater Utilizing a Semicircular Section Tubular Photoreactor
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作者 Carlos Ramiro Escalera Omar Alberto Ormachea 《Journal of Environmental Science and Engineering(A)》 2012年第9期1071-1082,共12页
A semicircular section tubular photoreactor has been constructed, characterized and applied to the treatment of groundwater contaminated with As(V) by means of the SORAS (solar oxidation and removal of arsenic) te... A semicircular section tubular photoreactor has been constructed, characterized and applied to the treatment of groundwater contaminated with As(V) by means of the SORAS (solar oxidation and removal of arsenic) technique, using ferrous and citrate salts. The solar concentrator was built with recyclable waste materials: glass tubes from fluorescent lamps and 6-inch diameter PVC pipes cut in half and covered by aluminum foil. The reactor concentrates solar radiation up to 2.8 times its natural intensity. Batch irradiation experiments followed by controlled agitation (shear rate = 30-33 s^-1; 20 min agitation period) showed that the photoreactor accelerates the formation of settleable floccules (Dp 〉 0.5mm), compared with a fluorescent lamp glass tube alone and a 2 L PET (polyethylene terephthalate) bottle. Irradiation times necessary for floccule formation in the photoreactor, the fluorescent lamp tube and the PET bottle were 15 min, 25 min and 60 min, respectively. Continuous flow experiments using a photoreactor with a photo-collection area of 0.9 m^2 and a hydraulic retention time (equal to the irradiation time) of 15 rain showed that immediate formation of floccules of good settleability occurs when the solution is subjected to moderate agitation (33 s^-1). An efficiency of 98.36% for As(V) removal was obtained with a final concentration of 16.5 ktg/L in decanted waters. In accordance to these results, the photoreactor is able to treat approximately 130 L/m^2 within a 5-h period with UVA irradiation intensities of 50-70 W/mE. 展开更多
关键词 Tubular photoreactor arsenic removal SORAS (solar oxidation and removal of arsenic GROUNDWATER flocculation.
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Preliminary Study of the Characteristics and Genesis of Arsenate Minerals in the Oxidized Zone of the Debao Skarn-Type Cu-Sn Ore Deposit in Guangxi
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作者 Li Yi Lai Lairen Institute of Geology and Mineral Resources,China National Nonferrous Metals Industry Corporation Zhang Zhongmin 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1991年第2期187-194,共8页
Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate m... Through the study of the oxidized zone of the Debao skarn-type Cu-Sn deposit in Guangxi, the authorshave found 14 arsenate minerals, most of which are for the first time reported in China. They are mainly Cuarsenate minerals with subordinate Cu-Pb arsenate minerals and minor Fe-Pb-Ba varieties. Based on their paragenesis these minerals may be divided into the following series: (1) the clinoclasite-olivenite-cornwallite- cornubite- debaoite- copper silicarsenate association, (2) the scorodite- carminite- beudan-tite-bayldonite- duftite association, and (3) the scorodite-Ba-bearing pharmacosiderite- dussertite association. Arsenate minerals are formed generally in the oxidized zone of the sulfide-type deposits which lie in thewarm, humid and rainy torrid-subtropical zone with pH=6-8 and contain large amounts of arsenopyrite andcarbonate rocks. 展开更多
关键词 Preliminary Study of the Characteristics and Genesis of Arsenate Minerals in the Oxidized Zone of the Debao Skarn-Type Cu-Sn Ore Deposit in Guangxi Cu Sn
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Arsenic redox transformation by Pseudomonas sp.HN-2 isolated from arsenic-contaminated soil in Hunan,China 被引量:6
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作者 Zhennan Zhang Naiyi Yin +2 位作者 Xiaolin Cai Zhenzhou Wang Yanshan Cui 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2016年第9期165-173,共9页
A mesophilic,Gram-negative,arsenite[As(Ⅲ)]-oxidizing and arsenate[As(V)]-reducing bacterial strain,Pseudomonas sp.HN-2,was isolated from an As-contaminated soil.Phylogenetic analysis based on 16 S r RNA gene sequ... A mesophilic,Gram-negative,arsenite[As(Ⅲ)]-oxidizing and arsenate[As(V)]-reducing bacterial strain,Pseudomonas sp.HN-2,was isolated from an As-contaminated soil.Phylogenetic analysis based on 16 S r RNA gene sequencing indicated that the strain was closely related to Pseudomonas stutzeri.Under aerobic conditions,this strain oxidized 92.0%(61.4 μmol/L) of arsenite to arsenate within 3 hr of incubation.Reduction of As(V) to As(Ⅲ) occurred in anoxic conditions.Pseudomonas sp.HN-2 is among the first soil bacteria shown to be capable of both aerobic As(Ⅲ) oxidation and anoxic As(V) reduction.The strain,as an efficient As(Ⅲ) oxidizer and As(V) reducer in Pseudomonas,has the potential to impact arsenic mobility in both anoxic and aerobic environments,and has potential application in As remediation processes. 展开更多
关键词 arsenic Arsenite oxidation Arsenate reduction Detoxification Pseudomonas
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Antimony oxidation and adsorption by in-situ formed biogenic Mn oxide and Fe–Mn oxides 被引量:12
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作者 Yaohui Bai William A.Jefferson +2 位作者 Jinsong Liang Tingting Yang Jiuhui Qu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2017年第4期126-134,共9页
Antimony(Sb), which can be toxic at relatively low concentrations, may co-exist with Mn(Ⅱ)and/or Fe(Ⅱ) in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption ... Antimony(Sb), which can be toxic at relatively low concentrations, may co-exist with Mn(Ⅱ)and/or Fe(Ⅱ) in some groundwater and surface water bodies. Here we investigated the potential oxidation and adsorption pathways of Sb(Ⅲ and V) species in the presence of Mn(Ⅱ) and Mn-oxidizing bacteria, with or without Fe(Ⅱ). Batch experiments were conducted to determine the oxidation and adsorption characteristics of Sb species in the presence of biogenic Mn oxides(BMOs), which were formed in-situ via the oxidation of Mn(Ⅱ) by a Mn-oxidizing bacterium(Pseudomonas sp. QJX-1). Results indicated that Sb(Ⅲ) ions could be oxidized to Sb(V) ions by BMO, but only Sb(V) originating from Sb(Ⅲ) oxidation was adsorbed effectively by BMO. Introduced Fe(Ⅱ) was chemically oxidized to Fe OOH, the precipitates of which mixed with BMO to form a new compound, biogenic Fe–Mn oxides(BFMO). The BMO part of the BFMO mainly oxidized and the Fe OOH of the BFMO mainly adsorbed the Sb species. In aquatic solutions containing both As(Ⅲ) and Sb(Ⅲ), the BFMO that formed in-situ preferentially oxidized Sb over As but adsorbed As more efficiently. Chemical analysis and reverse transcription real-time polymerase chain reaction revealed that the presence of Fe(Ⅱ), As(Ⅲ) and Sb(Ⅲ) accelerated the oxidation of Mn(Ⅱ) but inhibited the activity of Mn-oxidizing bacteria. These results provide significant insights into the biogeochemical pathways of Sb, Mn(Ⅱ) in aquatic ecosystems, with or without Fe(Ⅱ). 展开更多
关键词 Biogenic Mn oxide Biogenic Fe–Mn oxides Oxidation and adsorption Antimony arsenic
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Photooxidation of arsenic(Ⅲ) to arsenic(Ⅴ) on the surface of kaolinite clay 被引量:4
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作者 Wei Ding Yajie Wang +3 位作者 Yingtan Yu Xiangzhi Zhang Jinjun Li Feng Wu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第10期29-37,共9页
As one of the most toxic heavy metals, the oxidation of inorganic arsenic has drawn great attention among environmental scientists. However, little has been reported on the solar photochemical behavior of arsenic spec... As one of the most toxic heavy metals, the oxidation of inorganic arsenic has drawn great attention among environmental scientists. However, little has been reported on the solar photochemical behavior of arsenic species on top-soil. In the present work, the influencing factors(p H, relative humidity(RH), humic acid(HA), trisodium citrate, and additional iron ions) and the contributions of reactive oxygen species(ROS, mainly HO^- and HO2^-/O2^-) to photooxidation of As(Ⅲ) to As(Ⅴ) on kaolinite surfaces under UV irradiation(λ = 365 nm)were investigated. Results showed that lower p H facilitated photooxidation, and the photooxidation efficiency increased with the increase of RH and trisodium citrate.Promotion or inhibition of As(Ⅲ) photooxidation by HA was observed at low or high dosages, respectively. Additional iron ions greatly promoted the photooxidation, but excessive amounts of Fe^2+competed with As(Ⅲ) for oxidation by ROS. Experiments on scavengers indicated that the HOUradical was the predominant oxidant in this system.Experiments on actual soil surfaces proved the occurrence of As(Ⅲ) photooxidation in real topsoil. This work demonstrates that the photooxidation process of As(Ⅲ) on the soil surface should be taken into account when studying the fate of arsenic in natural soil newly polluted with acidic wastewater containing As(Ⅲ). 展开更多
关键词 Photochemical oxidation arsenic speciation Soil clay minerals Iron species Hydroxyl radical
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Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic(+3 oxidation state)methyltransferase-knockout mice 被引量:8
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作者 Jenna M.Currier Christelle Douillet +1 位作者 Zuzana Drobná Miroslav Styblo 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2016年第11期104-112,共9页
Arsenic methyltransferase(As3mt) catalyzes the conversion of inorganic arsenic(i As) to its methylated metabolites, including toxic methylarsonite(MAs~Ⅲ) and dimethylarsinite(DMAs~Ⅲ). Knockout(KO) of As3 m... Arsenic methyltransferase(As3mt) catalyzes the conversion of inorganic arsenic(i As) to its methylated metabolites, including toxic methylarsonite(MAs~Ⅲ) and dimethylarsinite(DMAs~Ⅲ). Knockout(KO) of As3 mt was shown to reduce the capacity to methylate i As in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type(WT) mice exposed to arsenite(iA s~Ⅲ) in drinking water. WT mice were exposed to50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or30 mg/L As. iA s~Ⅲaccounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iA s and methylated arsenicals: iA s~Ⅲ, MAs~Ⅲand DMAs~Ⅲ represented 55%‐68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAs~Ⅲ, were found in the intestine of WT, but not As3mt-KO mice,suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iA s methylation in adverse effects of iA s exposure. 展开更多
关键词 arsenic speciation analysis Hydride generation-cryotrapping-atomic absorption spectrometry arsenic(+ 3 oxidation state) methyltransferase As3mt knockout mice
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Mitochondrial dysfunction,oxidative stress and apoptotic induction in microglial BV-2 cells treated with sodium arsenate 被引量:5
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作者 Wafa Kharroubi Samia Hai Ahmed +4 位作者 Thomas Nury Pierre Andreoletti Rachid Sakly Mohamed Hammami Gerard Lizard 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2017年第1期44-51,共8页
The treatment of microglial BV-2 cells with sodium arsenate(As(V):0.1-400 μmol/L — 48 hr)induces a dose-dependent response.The neurotoxic effects of high concentrations of As(V)(100,200 and 400 μmol/L) are... The treatment of microglial BV-2 cells with sodium arsenate(As(V):0.1-400 μmol/L — 48 hr)induces a dose-dependent response.The neurotoxic effects of high concentrations of As(V)(100,200 and 400 μmol/L) are characterized by increased levels of mitochondrial complexesⅠ,Ⅱ,and Ⅳ followed by increased superoxide anion generation.Moreover,As(V) triggers an apoptotic mode of cell death,demonstrated by an apoptotic SubG1 peak,associated with an alteration of plasma membrane integrity.There is also a decrease in transmembrane mitochondrial potential and mitochondrial adenosine triphosphate ATP.It is therefore tempting to speculate that As(V) triggers mitochondrial dysfunction,which may lead to defective oxidative phosphorylation subsequently causing mitochondrial oxidative damage,which in turn induces an apoptotic mode of cell death. 展开更多
关键词 Sodium arsenate Microglial BV-2 cells Mitochondrial dysfunction Oxidative phosphorylation complexes Superoxide anions Apoptosis
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Full scale amendment of a contaminated wood impregnation site with iron water treatment residues 被引量:1
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作者 Sanne Skov NIELSEN Peter KJELDSEN Rasmus JAKOBSEN 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2016年第4期169-178,共10页
Iron water treatment residues (Fe-WTR) are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe- WTR to a con... Iron water treatment residues (Fe-WTR) are a free by-product of the treatment of drinking water with high concentration of iron oxides and potential for arsenic sorption. This paper aims at applying Fe- WTR to a contaminated site, measuring the reduction in contaminant leaching, and discussing the design of delivery and mixing strategy for soil stabilization at field scale and present a cost-effective method of soil mixing by connnon contractor machinery. Soil contaminated by As, Cr, and Cu at an abandoned wood impregnation site was amended with 0.22% (dw) Fe-WTR. To evaluate the full scale amendment a 100 mtest site and a control site (without amendment) were monitored for 14 months. Also soil analysis of Fe to evaluate the degree of soil and Fe-WTR mixing was done. Stabilization with Fe-WTR had a significant effect on leachable contaminants, reducing pore water As by 93%, Cu by 91% and Cr by 95% in the upper samplers. Dosage and mixing of Fe-WTR in the soil proved to be difficult in the deeper part of the field, and Pire water concentrations of arsenic was generally higher.Despite water logged conditions no increase in dissolved iron or arsenic was observed in the amended soil. Our field scale amendment of contaminated soil was overall successful in decreasing leaching of As, Cr and Cu. With minor improvements in the mixing and delivery strategy, this stabilization method is suggested for use in cases, where leaching ofCu, Cr and As constitutes a risk for groundwater and freshwater. 展开更多
关键词 Field experiment Iron oxide arsenic Stabilization Wood preservation sites
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