Fracionamento químico e especiação in situ de As em áreas alagadas (Nhecolândia - MS) utilizando a técnica de Difusão em Filmes Finos por Gradiente de Concentração (DGT)
Carregando...
Arquivos
Data
2020-07-14
Autores
Elias, Lucas Pellegrini
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Distribuído de maneira heterogênea na Crosta, o arsênio (As) é um elemento biodisponível nos mais variados sistemas ambientais. Sob quatro estados de oxidação, é caracterizado por suas espécies orgânicas e inorgânicas (AsV e AsIII), sendo estas últimas as mais tóxicas. Considerado como não-essencial aos processos biológicos, também pode apresentar propriedades nocivas aos seres vivos quando expostos a altas concentrações, principalmente no que diz respeito às suas espécies inorgânicas. Apesar de sua presença no ambiente estar relacionada a processos naturais, tais como intemperismo, vulcanismo e atividades biológicas, a mobilização do arsênio também é resultante de ações antrópicas, como mineração, atividades industriais e agrícolas. A biotransformação desses compostos é regular, formando espécies voláteis que podem ser adsorvidas, lixiviadas, reduzidas etc. Diante desta problemática, torna-se fundamental o monitoramento deste elemento, sobretudo nos sistemas aquáticos. Portanto, o aprimoramento de métodos analíticos é essencial para a determinação, especiação e possível mitigação de seus impactos. Com isso, a técnica de Difusão em Filmes Finos por Gradiente de Concentração (DGT) surge como uma significativa ferramenta para a avaliação in situ de arsênio, selecionando e pré-concentrando o analito no sistema a ser monitorado. Permitindo a determinação das frações lábeis dos elementos em baixas concentrações, os dispositivos apontam características robustas para aplicação em diferentes ambientes, apresentando a vantagem de preservar as espécies sorvidas e permitindo amostragens por longos períodos. Em vista da contaminação de arsênio em diferentes áreas do Pantanal brasileiro, a aplicação da técnica se deu na sub-região da Nhecolândia (MS). Esta área é caracterizada por suas complexas características hidrológicas e hidroquímicas e pela presença natural desse elemento em suas águas. Determinações in situ foram realizadas, nas quais dispositivos foram imersos em três lagoas distintas para avaliar o comportamento biogeoquímico de arsênio e a sua biodisponibilidade no ambiente. Amostras foram coletadas de ambas as lagoas para a avaliação in lab do elemento em diferentes frações. Os resultados obtidos indicam a presença de suas espécies inorgânicas nas águas superficiais das lagoas, em diferentes concentrações.
Heterogeneously distributed in the crust, arsenic (As) is a bioavailable element in various environmental systems. Under four oxidation states, it is characterized by its organic and inorganic species (AsV and AsIII), the latter being the most toxic. Considered as non-essential to biological processes, As can be one of the most harmful pollutants to living beings under high exposures, especially with regard to its inorganic species. Although its presence in the environment is related to natural processes, As mobilization is also the result of anthropic actions, such as industrial and agricultural activities and mining. The biotransformation of these compounds is regular, forming volatile species, which can be adsorbed, leached, reduced etc. In view of this problem, monitoring of this element is essential, especially in aquatic systems. Therefore, the improvement of analytical methods is crucial for the determination, speciation analysis and possible mitigation of impacts. Thus, the Diffusive Gradients in Thin films technique (DGT) emerges as a significant tool for the in situ assessment of As as well as for selecting and pre-concentrating the analyte in the system to be monitored. Allowing the determination of labile fractions of the analytes in low concentrations, the devices point out robust characteristics for application in different systems, presenting the advantage of preserving the adsorbed species and allowing sampling for long periods. In view of the arsenic contamination in different areas of the Brazilian Pantanal, DGT was applied in lakes of the Nhecolândia (MS) sub-region. This area is characterized by its complex hydrological and hydrochemical systems and by the natural presence of this element in its waters. In situ determinations were performed, in which DGT devices were immersed in three distinct lakes to assess the biogeochemical behavior of arsenic and bioavailability in the environment. Samples were collected from both lakes for in lab evaluation of the element in different fractions. The results obtained indicate the presence of their inorganic species in surface waters of the lakes, in different concentrations.
Heterogeneously distributed in the crust, arsenic (As) is a bioavailable element in various environmental systems. Under four oxidation states, it is characterized by its organic and inorganic species (AsV and AsIII), the latter being the most toxic. Considered as non-essential to biological processes, As can be one of the most harmful pollutants to living beings under high exposures, especially with regard to its inorganic species. Although its presence in the environment is related to natural processes, As mobilization is also the result of anthropic actions, such as industrial and agricultural activities and mining. The biotransformation of these compounds is regular, forming volatile species, which can be adsorbed, leached, reduced etc. In view of this problem, monitoring of this element is essential, especially in aquatic systems. Therefore, the improvement of analytical methods is crucial for the determination, speciation analysis and possible mitigation of impacts. Thus, the Diffusive Gradients in Thin films technique (DGT) emerges as a significant tool for the in situ assessment of As as well as for selecting and pre-concentrating the analyte in the system to be monitored. Allowing the determination of labile fractions of the analytes in low concentrations, the devices point out robust characteristics for application in different systems, presenting the advantage of preserving the adsorbed species and allowing sampling for long periods. In view of the arsenic contamination in different areas of the Brazilian Pantanal, DGT was applied in lakes of the Nhecolândia (MS) sub-region. This area is characterized by its complex hydrological and hydrochemical systems and by the natural presence of this element in its waters. In situ determinations were performed, in which DGT devices were immersed in three distinct lakes to assess the biogeochemical behavior of arsenic and bioavailability in the environment. Samples were collected from both lakes for in lab evaluation of the element in different fractions. The results obtained indicate the presence of their inorganic species in surface waters of the lakes, in different concentrations.
Descrição
Palavras-chave
Arsênio, DGT, Especiação, Fracionamento químico, Lagoas, Arsenic, Speciation, Chemical fractionation, Lakes