Arsenic Speciation
Mostrando 13-22 de 22 artigos, teses e dissertações.
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13. Especiação e remoção de arsenio de aguas utilizando voltametria de redissolução catodica e processos oxidativos avançados / Arsenic speciation and removal from waters employing stripping voltammetry and advanced oxidatives process
Arsenic exists in various chemical forms in the environment, including as organic and inorganic species, originating from natural and anthropogenic sources. As for other potential toxic elements, the concentration limit for arsenic in drinking water is decreasing as a result of observed chronic poisoning coming from low exposure doses. In drinking water, the
Publicado em: 2005
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14. DEVELOPMENT OF METHODOLOGIES FOR THE ARSENIC SPECIATION IN WATERS AND SALINE MATRICES BY ADSORPTIVE CATHODIC STRTIPPING VOLTAMMETRY / DESENVOLVIMENTO DE METODOLOGIAS PARA A ESPECIAÇÃO DE ARSÊNIO EM ÁGUAS E MATRIZE SALINAS EMPREGANDO VOLTAMETRIA ADSORTIVA DE REDISSOLUÇÃO CATÓDICA
The present work reports the development of methodologies for the arsenic speciation in waters and saline matrices by adsorptive cathodic stripping voltammetry (AdCSV). The determination of As(III) by AdCSV was investigated and optimized using the organic ligand sodium diethyldithiocarbamate (DDC) in acidic medium. The main experimental parameters that have
Publicado em: 2005
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15. STUDY OF THE CHEMICAL SPECIATION OF ARSENIC AND SELENIUM IN WATER CURRENTS AND LIQUID EFFLUENTS OF PETROLEUM REFINERIES / ESTUDO DA ESPECIAÇÃO QUÍMICA DE ARSÊNIO E SELÊNIO EM CORRENTES AQUOSAS E EFLUENTES DE REFINARIA DE PETRÓLEO
The concentrations of arsenic in oil can vary of 10 the 30 mgkg-1. The selenium is found in effluent of the petroliferous industry, had its presence in the oil, between 0.03 -1,4 mg.L-1 depending on its geochemistry origin. For chemical reasons, arsenic shows a high affinity to sulfur, similar as selenium, thus following this element through the whole petrol
Publicado em: 2005
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16. Especiação analítica de compostos de arsênio empregando métodos voltamétricos e polarográficos: uma revisão comparativa de suas principais vantagens e aplicações
This paper provides a review on voltammetric and polarographic methods for the speciation analysis of inorganic and organic arsenic compounds in different matrices. A discussion on the main advantages of electroanalytical methods in comparison with other analytical methods employed for arsenic speciation is presented. The mechanistic aspects of the most rele
Química Nova. Publicado em: 2004-04
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17. Especiação de Arsênio - uma revisão
This paper provides a review on separation methods and analytical techniques for the determination of several species of organic and inorganic arsenic in different matrices. Arsenic is an element whose speciation is of particular interest due to the great variation of toxicity levels exhibited for its different chemical forms. Arsenic (III) and As (V) are th
Química Nova. Publicado em: 2000-02
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18. Assessment of occupational exposure to inorganic arsenic based on urinary concentrations and speciation of arsenic.
An analytical speciation method, capable of separating inorganic arsenic (As (V), As (III] and its methylated metabolites (MMAA, DMAA) from common, inert, dietary organoarsenicals, was applied to the determination of arsenic in urine from a variety of workers occupationally exposed to inorganic arsenic compounds. Mean urinary arsenic (As (V) + As (III) + MMA
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19. Mechanisms of Arsenic Hyperaccumulation in Pteris vittata. Uptake Kinetics, Interactions with Phosphate, and Arsenic Speciation1
The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata. In an 18-d hydroponic experiment with varying concentrations of arsenate and phosphate,
American Society of Plant Biologists.
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20. The influence of sulfur and iron on dissolved arsenic concentrations in the shallow subsurface under changing redox conditions
The chemical speciation of arsenic in sediments and porewaters of aquifers is the critical factor that determines whether dissolved arsenic accumulates to potentially toxic levels. Sequestration of arsenic in solid phases, which may occur by adsorption or precipitation processes, controls dissolved concentrations. We present synchrotron x-ray absorption spec
National Academy of Sciences.
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21. The Distribution of Arsenate and Arsenite in Shoots and Roots of Holcus lanatus is Influenced by Arsenic Tolerance and Arsenate and Phosphate Supply
The recent discovery that phytochelatins are important for arsenic (As) detoxification in terrestrial plants results in the necessity to understand As speciation and metabolism in plant material. A hydroponic study was therefore conducted to examine the effects of different levels of phosphate and arsenate [As(V)] on As speciation and distribution in tol
The American Society for Plant Biologists.
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22. Mineral surfaces and bioavailability of heavy metals: A molecular-scale perspective
There is a continual influx of heavy metal contaminants and pollutants into the biosphere from both natural and anthropogenic sources. A complex variety of abiotic and biotic processes affects their speciation and distribution, including adsorption onto and desorption from mineral surfaces, incorporation in precipitates or coprecipitates, release throug
The National Academy of Sciences.