Avaliação da qualidade ambiental de áreas afetadas por rejeitos de mineração após quatro anos: uma abordagem na caracterização da carcinofauna bentônica
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Data
2021-07-29
Autores
Marques, Thaciana Fabiola
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Universidade Federal do Espírito Santo
Resumo
The collapse of the Fundão dam (Mariana-MG) released a large number of mining tailings along the Rio Doce, reaching its mouth in the Atlantic Ocean. In this context, this work aimed to evaluate, spatially and temporally, the ecological descriptors and the relationship of macrobenthic carcinofauna with abiotic factors, including those that can be considered indicatives of the presence of mine tailings from the Fundão dam collapse., from the continental shelf of Espírito Santo to southern Bahia, during the period from October/2018 to July/2019, totaling four campaigns: spring, summer, autumn, and winter. Sectors: Abrolhos (AB), Norte (NO), Foz do Rio Doce (FZ), Costa das Algas (CA), and Sul (SU). In the laboratory, each sample was washed and, with the assistance of a magnifying glass, the crustaceans were sorted and identified at the lowest possible taxonomic level, the richness of taxa, density (ind./mL), and diversity (H') were across sectors, campaigns and depths. The relationship of abiotic factors with the density of the crustacean taxa in the sectors, campaigns, and depths was verified by means of redundancy analysis (RDA). The highest values of richness and diversity occurred in the AB and SU sectors, which differed significantly from the FZ (p < 0.05). In addition, these descriptors had their highest values in summer and winter, and in the greatest depths (p < 0, 05). Although the highest density was registered in the FZ sector, in the autumn season and in greater depths, there were no significant differences. In the FZ sector, the highest OM contents were registered, as well as the highest percentage of sludge and metals, mainly Barium, Copper, and Nickel, which possibly presents a direct relationship with the ore tailings from the collapse of the Fundão dam. On the other hand, the CA, AB, and SU sectors were positively associated with higher CaCO3 contents. The results for each sector revealed differences in the structure of the community, where Amphipoda predominated in FZ, AB, and NO sectors, Ostracoda in the CA sector, and Copepoda and Ostracoda in the SU sector, showing that the varieties of the studied area influence the preference of organisms by environmental conditions. The results attenuated a low richness, diversity, and possible increase in density in the FZ sector, due to the presence of Phoxocephalidae (Amphipoda), suggesting a certain resistance and capacity of this family in environmental changes, such as high metals observed in this sector. Thus, these results can show that even four years after the collapse of the Fundão dam, the FZ sector still presents a high degree of contamination suffered by mining tailings, which directly affected the structuring of the benthic crustacean community, especially in places close to the mouth of the Rio Doce. In this context, works related to the characterization of macrobenthic carcinofauna are essential to understand the ecological performance of organisms in places, as well as their relationship to disturbances caused by anthropic action, such as the rupture of the mining dam, which can also help in monitoring and assessment of environmental impacts.
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Fauna bentônica , metais pesados , Oceano Atlântico , Rio Doce , substrato inconsolidado