Assessment of biological and biochemical proprieties in soil and tailing from iron ore mining operations under rehabilitation

Abstract

Mining activities have grown worldwide to meet industrial demands and technological development. However, the process of mineral extraction has negative impacts on biodiversity, besides generating tailings that are vulnerable to accidents and which can be sources of environmental contamination. Thus, by law, rehabilitation of the local ecosystem is necessary. For this, revegetation has provided good results in rehabilitation of ecosystem functions, as well as some soil microorganisms, such as arbuscular mycorrhizal fungi that besides the wide spatial distribution, are involved in process of soil aggregation, higher plant tolerance, water and nutrient absorption and glomalin production. In this sense, the objective of the first chapter was evaluate rehabilitation of areas after iron mining through biological and biochemical attributes of soil. For this, it was evaluated in the laboratory, enzyme activities involved in the C, N and P biogeochemical cycles, carbon and total nitrogen, biomass carbon, microbial respiration and soil bacterial metabolic activity. The results showed that soil biochemical attributes (carbon and nitrogen from biomass, ADF, urea and acid phosphatase) of areas under rehabilitation were increased in the short term over exposed soil areas, suggesting that rehabilitation is occurring progressively and that, In the short to medium term, the ecological functions of the soil can be fully restored. In the second chapter, the objective was investigate the arbuscular mycorrhizal fungi and their contribution to carbon stock in areas under rehabilitation in Urucum Mineral Complex. The results showed that species richness of mycorrhizal fungi reduced by about 50% with mining activity. However, with the revegetation progress it was observed that spores number and mycorrhizal colonization increased in period of two and three years of revegetation. The easily extractable and total glomalin-related soil protein content increased with the age of revegetation. Our data set indicates that improvements in status of FMAs responsible for providing GRSP content are positively related to soil carbon stock and restoration of ecological functions in rehabilitation areas. In third chapter the objective was evaluate how the iron mining tailings in Mariana affected the composition of bacterial communities, as well as the conditioning action of biochar under different pH conditions on activity, composition and diversity of bacterial communities.