Metais pesados em lavouras de tabaco (Nicotiana tabacum) tipo Virg?nia da regi?o sul do Brasil

• Ano de defesa: 2013
• Autor(a) principal: Zoffoli, Hugo Jos? de Oliveira
• Orientador(a): Amaral Sobrinho, Nelson Moura Brasil do
• Banca de defesa: Mazur, Nelson, Varella, Carlos Alberto Alves, Polidoro, Jos? Carlos, Per?z, Daniel Vidal, Burak, Diego Lang
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural do Rio de Janeiro
• Programa de Pós-Graduação: Programa de P?s-Gradua??o em Agronomia - Ci?ncia do Solo
• Departamento: Instituto de Agronomia
• País: Brasil
• Palavras-chave em Português: Metais pesados; Nicotiana tabacum; Fumo
• Palavras-chave em Inglês: Heavy metals; Tabacco
• Área do conhecimento CNPq: Agronomia
• Link de acesso: https://tede.ufrrj.br/jspui/handle/jspui/6531

In recent decades, smoking has been shown in medical research as a relevant or decisive factor for the occurrence of certain diseases, which are related to substances contained in cigarette smoke, among them are heavy metals, and some especially toxic. Different soil conditions, varieties and agrochemicals may result in different levels of heavy metals in the tobacco plants leaves, and in this way being present in the cigarette smoke. This study aims to identify the aspects related to the contribution of the heavy metals Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn in flue-cured tobacco leaves, produced in Southern Brazil. The study was conducted in the harvesting year of 2009, sampling the major agrochemicals used in the tobacco production, as well as soil sampled at two depths (0-20 and 20-40cm), and plant (root, X and B leaves) in 107 commercial fields of 38 municipalities. The soils were characterized, from profiles described in the field, and classified, and the geology identified from regional geological maps. In the plant and soil samples, the content of heavy metals, and chemical and granulometric parameters were determined. The total content of the elements was evaluated on several batches of agrochemicals and determined their applied loads. The fertilizers were identified as the main source of incorporation of heavy metals, among the agrochemicals used. Pesticides applied directly in shoots of tobacco plants contributed very little as source of heavy metals. The agrochemicals used in Brazilian tobacco crops provide, in general, for the main heavy metals non-essential to plants, an input lower than verified in most crops in various regions of the world, as reported in the international literature. Given the difficulty of statistical analysis for variables that had values below the analytical detection limit, it was developed a statistical procedure for evaluation of these types of data, designated as left censored. The proposed procedure, here named as method of semi-variance (SemiV) proved to be adequate, and superior to traditional substitution procedures, and comparable to procedures performed in sophisticated computer programs, and also to the latest methods reported in the literature. The interrelationship between soil and plant variables was assessed by means of different techniques related to multivariate analysis. The plant contents of As and Cr were not associated with the soil variables evaluated. The Hg content in all plant samples was below 0.03 mg kg-1, and 98% of plant samples showed levels of Se below 0.13 mg kg-1. Factors related to the total heavy metals content, the electrostatic adsorption, the specific adsorption, and soil acidity acted in a common way in explaining the variance of Mn, Zn, Cd and Pb in the plant. The common variance of Cu, Ni and Fe in the plant, which can be explained by soil variables, is associated with factors that govern the total contents of metals, electrostatic adsorption, specific adsorption, acidity and exchangeable levels of Na and K in soils. On a regional scale, the common factor associated with total soil heavy metals level is governed by geological formation, and represents the largest contribution of the explanation for the effect of soil variables on the Mn, Zn, Cd, Cu, Ni, Fe and Pb variability in the plant.