Revegetação de Áreas de Mineração com Presença de Substratos Sulfetados

• Ano de defesa: 2013
• Autor(a) principal: Silva, Silmara Costa
• Orientador(a): Dias, Luiz Eduardo
• Banca de defesa: Abrahão, Walter Antônio Pereira , Azevedo, Roberto Francisco de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Substratos Sulfetados; Pirita; Recuperação de áreas degradadas
• Palavras-chave em Inglês: Sulphide Substrates; Reclamation of degraded areas
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5511

The constant concern about the contamination of mineral exploration areas and pressure from society and environmental agencies promotes the search for efficient techniques for environmental remediation of these sites. The extraction of certain minerals such as gold may be associated with the generation of acid mine drainage, promoting the contamination of adjacent areas, than recovery plans more complex and costly are necessary. Moreover, it is notable the occurrence of mobilizing heavy metals and metalloids such as arsenic (As) resulting from acid mine drainage. Since the techniques of reclamation of mining are usually related to revegetation, this study aimed to evaluate different materials and cover forms of gold exploration sulfide substrate remaining in order to provide conditions for the establishment and growth of vegetation. The experiment was conducted in field with thirteen treatments in a factorial (1 x 1 x 1) + (2 x 3 x 2), with a model of three layers above the sulfide substrate slightly weathered (B2). The first, called capillary breaking layer (CQC), which has the function of preventing the rise of water by capillarity, was composed of crushed limestone or laterite. The second, called sealant layer (CS), which has the function of minimizing the drainage of water and the gas stream, when present, consisted of soil (A and B horizons of an Oxisol LVA) or very weathered sulphide substrate (B1). The last layer, called coverage layer (CC), whose function is to support the growth of plants, consisted of soil or B1. The species used for revegetation were Melinis minutiflora P. Beauv (fat grass), Stizolobium aterrimum Piper & Tracy (velvet bean), Lolium multiflorum Lam (ryegrass), Crotalaria spectabilis Roth. (crotalaria) and Stylosanthes spp. Stylosanthes capitata Vogel and S. macrocephala M. B. Ferr. et S. Costa (estilosante). It was analyzed the chemical, physical and mineralogical characteristics of these materials five months after planting, and evaluation of microbial activity and soil organic matter (MOS) ten and thirteen months after planting. We also evaluated the dry biomass and foliar contents of arsenic per treatment. The soil is very clayey (72 % clay), while the substrate B1 has silty loam texture (65 % silt). The moisture of the materials in CC averaged 0.11 kg kg-1 for soil and 0.03 kg kg-1 for substrate B1 (dry season), and 0.30 kg kg-1 for soil and 0.06 kg kg-1 for B1 (rainy season). After thirteen months, treatments that had the laterite CQC produced on average 0.98 t ha-1 (p < 0.01) more plant material than treatments containing crushed limestone, and foliar contents of As average in this treatment presented 6.12 mg kg-1 (p < 0.05) more than those which had laterite in CQC. The difference of biomass produced for treatments with soil or B1 in CS was significant only for treatments with crushed limestone in CQC. Treatments that had soil in CS produced on average 5.16 t ha-1 (p < 0.01) more biomass than those with B1 in CS. The average arsenic concentration available to the soil was significantly lower than that of the substrate B1. Thus, the presence of soil in CC caused the biomass significantly higher than in treatments with B1. The microbial biomass carbon (BMS-C) was significantly higher in the plots that received land in CC relative to B1, indicating lower environmental sustainability when the latter material is used as cover. The microbial quocient (qCO2), a relation between the amounts of CO2 generated per unit of microbial biomass per unit of time, showed high values, which are relatively higher for B1. Among the species used, the fat grass and crotalaria were more tolerant to B1 conditions and ryegrass was not established in this material. The use of soil as a constituent of the sealant layer and the cover layer resulted in better conditions for plant establishment. However, depending on the combination of layers, it is possible to use B1 in CC and CS, exerting less pressure on the use of soils in other areas, thus representing a considerable cost reduction of recovery area.