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A Química Ambiental no Brasil
Mozeto, Antonio A .;Jardim, Wilson de F.;
Química Nova , 2002, DOI: 10.1590/S0100-40422002000800002
Abstract: defining environmental chemistry is a not an easy task because it encompasses many different topics. according to stanley e. manahan, author of a classical textbook of environmental chemistry, this branch could be defined as the one centered in the study of the sources, transport, effects and fates of chemical species in the water, soil, and air environments, as well as the influence of human activity upon these processes. more recently, new knowledge emerged from the environmental toxicology allowed to go even deeper in the meaning of 'effects' and 'fates' of a continuous growing number of organic and inorganic species disposed in water bodies, soils and atmosphere. toxicity tests became an important tool to evaluate the environmental impact of such species to a great number of organisms, thus allowing to set quality criteria for drinking water, sediments and biota. the state of art shows that environmental chemistry is a multi-inter disciplinary science by nature; therefore, it needs more than a limited, unique-approach and non-oriented set of data to understand the nature of natural processes. taking all these aspects into consideration, one can say that environmental chemistry in brazil is now a well established area of research within the classical areas of the chemistry, with a large number of emerging groups as well research groups with worldwide recognition.
A Química Ambiental no Brasil
Mozeto Antonio A .,Jardim Wilson de F.
Química Nova , 2002,
Abstract: Defining environmental chemistry is a not an easy task because it encompasses many different topics. According to Stanley E. Manahan, author of a classical textbook of Environmental Chemistry, this branch could be defined as the one centered in the study of the sources, transport, effects and fates of chemical species in the water, soil, and air environments, as well as the influence of human activity upon these processes. More recently, new knowledge emerged from the Environmental Toxicology allowed to go even deeper in the meaning of 'effects' and 'fates' of a continuous growing number of organic and inorganic species disposed in water bodies, soils and atmosphere. Toxicity tests became an important tool to evaluate the environmental impact of such species to a great number of organisms, thus allowing to set quality criteria for drinking water, sediments and biota. The state of art shows that environmental chemistry is a multi-inter disciplinary science by nature; therefore, it needs more than a limited, unique-approach and non-oriented set of data to understand the nature of natural processes. Taking all these aspects into consideration, one can say that Environmental Chemistry in Brazil is now a well established area of research within the classical areas of the Chemistry, with a large number of emerging groups as well research groups with worldwide recognition.
Bioaccumulation of Polycyclic Aromatic Hydrocarbons and Mercury in Oysters (Crassostrea rhizophorae) from Two Brazilian Estuarine Zones
Ronaldo J. Torres,Augusto Cesar,Camilo D. S. Pereira,Rodrigo B. Choueri,Denis M. S. Abessa,Marcos R. L. do Nascimento,Pedro S. Fadini,Antonio A. Mozeto
International Journal of Oceanography , 2012, DOI: 10.1155/2012/838320
Abstract: Nowadays, organisms are increasingly being used in biomonitoring to assess bioavailability and bioaccumulation of contaminants. This approach can use both native and transplanted organisms in order to accomplish this task. In Brazil, most of the studies related to bioaccumulation of contaminants in oysters deal with metals. The present work employs this kind of test in Brazilian coastal estuaries (Santos and Paranaguá) to evaluate total mercury and polycyclic aromatic hydrocarbon contamination in sediments and oysters (native and caged Crassostrea rhizophorae). The methodologies employed were based on known USEPA methods. Results have shown a significant contamination in Santos sediments and consequent bioavailability of organisms. Paranaguá sediments presented lower contamination in sediments, but native oysters were able to accumulate total Hg. The experiments done with caged oysters did not show significant bioaccumulation of Hg and PAHs in the Paranaguá site, but proved to be an excellent tool to assess bioavailability in the Santos estuary since they were able to bioaccumulate up to 1,600% of total PAH in the samples from the inner part of this estuary when compared to control organisms. Multivariate statistical analyses employed to these results have separated the sites evaluated and the most contaminated samples from the least contaminated.
Bioaccumulation of Polycyclic Aromatic Hydrocarbons and Mercury in Oysters (Crassostrea rhizophorae) from Two Brazilian Estuarine Zones
Ronaldo J. Torres,Augusto Cesar,Camilo D. S. Pereira,Rodrigo B. Choueri,Denis M. S. Abessa,Marcos R. L. do Nascimento,Pedro S. Fadini,Antonio A. Mozeto
International Journal of Oceanography , 2012, DOI: 10.1155/2012/838320
Abstract: Nowadays, organisms are increasingly being used in biomonitoring to assess bioavailability and bioaccumulation of contaminants. This approach can use both native and transplanted organisms in order to accomplish this task. In Brazil, most of the studies related to bioaccumulation of contaminants in oysters deal with metals. The present work employs this kind of test in Brazilian coastal estuaries (Santos and Paranaguá) to evaluate total mercury and polycyclic aromatic hydrocarbon contamination in sediments and oysters (native and caged Crassostrea rhizophorae). The methodologies employed were based on known USEPA methods. Results have shown a significant contamination in Santos sediments and consequent bioavailability of organisms. Paranaguá sediments presented lower contamination in sediments, but native oysters were able to accumulate total Hg. The experiments done with caged oysters did not show significant bioaccumulation of Hg and PAHs in the Paranaguá site, but proved to be an excellent tool to assess bioavailability in the Santos estuary since they were able to bioaccumulate up to 1,600% of total PAH in the samples from the inner part of this estuary when compared to control organisms. Multivariate statistical analyses employed to these results have separated the sites evaluated and the most contaminated samples from the least contaminated. 1. Introduction Some organic and inorganic chemical contaminants have the capacity of persisting in the environment, bioaccumulate in tissues, and are toxic to organisms. The main classes of elements and compounds that belong to this category are some metals such as mercury, cadmium, and lead as well as those denominated POPs (persistent organic pollutants) such as pesticides, dioxins, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) [1, 2]. Once in the environment, the contaminants interact with sediments, water column, and organisms; such interactions are controlled by several physical and chemical processes, and the final result may be the chemical release, immobilization, or their transformation into more reactive forms or subproducts, which are more effectively available to organisms [3]. Bioavailability is also governed by kinetics and partitioning of the contaminant in the environment [4]. Bioaccumulation is the process by which a chemical is absorbed by an organism exposed to it. It is a net result of competing processes of absorption, ingestion, digestion, and excretion [5] and involves also the endogenous processes of biological depuration. Bioaccumulation studies can
Sulfetos volatilizáveis por acidifica？？o e metais extraídos simultaneamente na avalia？？o de sedimentos de água doce
Fagnani, Enelton;Guimar？es, José Roberto;Mozeto, Antonio Aparecido;Fadini, Pedro Sérgio;
Química Nova , 2011, DOI: 10.1590/S0100-40422011000900022
Abstract: this paper discusses the historical and methodological fundaments of the dynamics and quantification of acid volatile sulfides (avs) and simultaneously extracted metals (sem) in aquatic sediments. it also discusses the sem/avs relationship, which involves several controversial aspects such as sulfide stability, sulfide-organic matter interaction, and the inability to predict the toxicity of organic compounds in the environment. this relationship is an important tool for the inference of metal bioavailability. the use of ecotoxicological tests with target organisms regulated by international standards is also a relevant aspect.
Extra o de matéria organica aquática por abaixamento de temperatura: uma metodologia alternativa para manter a identidade da amostra
Almeida Rosana N. H. Martins de,Mozeto Antonio Aparecido,Zara Luiz Fabrício,Rosa André Henrique
Química Nova , 2003,
Abstract: In this work was developed an alternative methodology to separation of aquatic organic matter (AOM) present in natural river waters. The process is based in temperature decreasing of the aqueous sample under controlled conditions that provoke the freezing of the sample and separation of the dark extract, not frozen and rich in organic matter. The results showed that speed of temperature decreasing exerts strongly influence in relative recovery of organic carbon, enrichment and time separation of the organic matter present in water samples. Elemental composition, infrared spectra and thermal analysis results showed that the alternative methodology is less aggressive possible in the attempt of maintaining the integrity of the sample.
Estudo da capacidade de complexa？？o e sua rela？？o com algumas variáveis ambientais em cinco represas do Rio Tietê/Brasil
Borges, Elisangela C. L.;Mozeto, Antonio Aparecido;Neves, Eduardo F. Almeida;Borges Neto, Waldomiro;Bezerra, José Mauro;
Química Nova , 2007, DOI: 10.1590/S0100-40422007000700002
Abstract: the copper and cadmium complexation properties in natural sediment suspensions of reservoirs of the tietê river were studied using the solid membrane copper and cadmium ion-selective electrodes. the complexation and the average conditional stability constants were determined under equilibrium conditions at ph=6.00 ± 0.05 in a medium of 1.0 mol l-1 sodium nitrate, using the scatchard method. the copper and cadmium electrodes presented nernstian behavior from 1x10-6 to 1x10-3 mol l-1 of total metal concentration. scatchard graphs suggest two classes of binding sites for both metals. a multivariate study was done to correlate the reservoirs and the variables: complexation properties, size, total organic carbon, volatile acid sulfide, eii and ph.
Extra？？o de matéria organica aquática por abaixamento de temperatura: uma metodologia alternativa para manter a identidade da amostra
Almeida, Rosana N. H. Martins de;Mozeto, Antonio Aparecido;Zara, Luiz Fabrício;Rosa, André Henrique;Rocha, Julio Cesar;Rom？o, Luciane Pimenta Cruz;Sargentini Junior, ézio;
Química Nova , 2003, DOI: 10.1590/S0100-40422003000200012
Abstract: in this work was developed an alternative methodology to separation of aquatic organic matter (aom) present in natural river waters. the process is based in temperature decreasing of the aqueous sample under controlled conditions that provoke the freezing of the sample and separation of the dark extract, not frozen and rich in organic matter. the results showed that speed of temperature decreasing exerts strongly influence in relative recovery of organic carbon, enrichment and time separation of the organic matter present in water samples. elemental composition, infrared spectra and thermal analysis results showed that the alternative methodology is less aggressive possible in the attempt of maintaining the integrity of the sample.
Green’s Function Technique and Global Optimization in Reconstruction of Elliptic Objects in the Regular Triangle  [PDF]
Antonio Scalia, Mezhlum A. Sumbatyan
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.23034
Abstract: The reconstruction problem for elliptic voids located in the regular (equilateral) triangle is studied. A known point source is applied to the boundary of the domain, and it is assumed that the input data is obtained from the free-surface input data over a certain finite-length interval of the outer boundary. In the case when the boundary contour of the internal object is unknown, we propose a new algorithm to reconstruct its position and size on the basis of the input data. The key specific character of the proposed method is the construction of a special explicit-form Green's function satisfying the boundary condition over the outer boundary of the triangular domain. Some numerical examples demonstrate good stability of the proposed algorithm.
Quantization and Stable Attractors in a DissipativeOrbital Motion  [PDF]
Daniel L. Nascimento, Antonio L. A. Fonseca
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.24030
Abstract: We present a method for determining the motion of an electron in a hydrogen atom, which starts from a field Lagrangean foundation for non-conservative systems that can exhibit chaotic behavior. As a consequence, the problem of the formation of the atom becomes the problem of finding the possible stable orbital attractors and the associated transition paths through which the electron mechanical energy varies continuously until a stable energy state is reached.
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