Estudo da distribuição espaço-temporal de chumbo total nos anéis concêntricos de árvores sobre áreas de falha geológica
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2023-01-24
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Universidade Estadual Paulista (Unesp)
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A aplicação de anéis arbóreos de crescimento como biomonitores da qualidade ambiental, constitui importante ferramenta para identificar e quantificar metais potencialmente tóxicos no ambiente, dado que as variáveis ambientais e o armazenamento dos contaminantes são registrados nos lenhos arbóreos. Os metais tóxicos, especificamente o chumbo, presente na série de decaimento do radônio 222 (Rn- 222), pode ser provindo de fontes antropogênicas e naturais, como as falhas geológicas. Dessa forma, o objetivo da presente pesquisa foi avaliar a distribuição espaço-temporal de chumbo total (210Pb, 214Pb e 206Pb) em anéis concêntricos arbóreos da Oiti (Licania tomentosa) e Sibipiruna (Caesalpinia pluviosa) sobre áreas de fratura geológica induzida. A área de estudo, delimitada para as coletas das amostras, localizou-se na FCT/UNESP, pois integra-se entre dois lineamentos de fratura geológica induzida. Para este propósito, por meio de uma sonda metálica acoplada em um equipamento motorizado, foram extraídas amostras cilíndricas dos anéis de crescimento das espécies arbóreas Oiti (Licania tomentosa) e Sibipiruna (Caesalpinia pluviosa). O estudo dendrocronológico foi determinado por meio de um microscópio eletrônico, acoplado a uma câmera digital e um software aplicativo. O método de digestão da amostra foi adaptado a partir do método proposto por Ogner (1983). Para a determinação da concentração de chumbo total nas amostras usou a técnica de voltametria de pulso diferencial por redissolução anódica (DPASV), usando uma célula eletroquímica contendo três eletrodos: eletrodo de mercúrio (Hanging Mercury Droping Electrode - HMDE), como eletrodo de trabalho, eletrodo de Ag/AgCl (3M KCl) como referência e eletrodo auxiliar de Pt. Por meio das análises estatísticas, a Análise de Componentes Principais (PCA) foi obtida pelos valores de concentração de chumbo em cada amostra e dos dados de variações ambientais anuais. A partir dos resultados das análises estatísticas, verificou que as variações anuais das concentrações de chumbo total nas espécies arbóreas, correlaciona com as tendências temporais do local de amostragem dessas espécies arbóreas, direção e localização da provável falha geológica na região, de modo a resultar uma emanação do gás radônio efetiva e intensa, coexistindo com uma elevada concentração de chumbo.
The application of tree growth rings as biomonitors of environmental quality is an important tool to identify and quantify potentially toxic metals in environment, given that environmental variables and the storage of contaminants are recorded in tree woods. Toxic metals, specifically lead, present in the radon-222 (Rn-222) decay series, may come from anthropogenic and natural sources, such as geological faults. Thus, the aim of this research was to evaluate the space-time distribution of total lead (210Pb, 214Pb and 206Pb) in tree concentric rings of Oiti (Licania tomentosa) and Sibipiruna (Caesalpinia pluviosa) over areas of induced geological fracture. The study area, delimited for sample collection, was located at FCT/UNESP, as it integrates between two lineaments of induced geological fracture. For this purpose, cylindrical samples were extracted from the growth rings of tree species Oiti (Licania tomentosa) and Sibipiruna (Caesalpinia pluviosa) using a metallic probe coupled to a motorized equipment. The dendrochronological study was determined using an electron microscope coupled to a digital camera and application software. The sample digestion method was adapted from the method proposed by Ogner (1983). To determine the total lead concentration in the samples, the differential pulse voltammetry technique by anodic stripping (DPASV) was used, using an electrochemical cell containing three electrodes: a mercury electrode (Hanging Mercury Dropping Electrode - HMDE), as a working electrode, Ag/AgCl electrode (3M KCl) as reference and auxiliary Pt electrode. Through statistical analyses, Principal Component Analysis (PCA) was obtained from the values of lead concentration in each sample and data from annual environmental variations. From the results of the statistical analyses, it was verified that the annual variations of the total lead concentrations in the tree species, correlate with the temporal trends of the sampling site of these tree species, direction and location of the probable geological fault in the region, in order to result in a effective and intense emanation of radon gas, coexisting with a high concentration of lead.
The application of tree growth rings as biomonitors of environmental quality is an important tool to identify and quantify potentially toxic metals in environment, given that environmental variables and the storage of contaminants are recorded in tree woods. Toxic metals, specifically lead, present in the radon-222 (Rn-222) decay series, may come from anthropogenic and natural sources, such as geological faults. Thus, the aim of this research was to evaluate the space-time distribution of total lead (210Pb, 214Pb and 206Pb) in tree concentric rings of Oiti (Licania tomentosa) and Sibipiruna (Caesalpinia pluviosa) over areas of induced geological fracture. The study area, delimited for sample collection, was located at FCT/UNESP, as it integrates between two lineaments of induced geological fracture. For this purpose, cylindrical samples were extracted from the growth rings of tree species Oiti (Licania tomentosa) and Sibipiruna (Caesalpinia pluviosa) using a metallic probe coupled to a motorized equipment. The dendrochronological study was determined using an electron microscope coupled to a digital camera and application software. The sample digestion method was adapted from the method proposed by Ogner (1983). To determine the total lead concentration in the samples, the differential pulse voltammetry technique by anodic stripping (DPASV) was used, using an electrochemical cell containing three electrodes: a mercury electrode (Hanging Mercury Dropping Electrode - HMDE), as a working electrode, Ag/AgCl electrode (3M KCl) as reference and auxiliary Pt electrode. Through statistical analyses, Principal Component Analysis (PCA) was obtained from the values of lead concentration in each sample and data from annual environmental variations. From the results of the statistical analyses, it was verified that the annual variations of the total lead concentrations in the tree species, correlate with the temporal trends of the sampling site of these tree species, direction and location of the probable geological fault in the region, in order to result in a effective and intense emanation of radon gas, coexisting with a high concentration of lead.
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Biomonitoramento, Anéis de crescimento arbóreos, Chumbo, Falha geológica, Biomonitoring, Arboreal growth rings, Geological fault, Lead