Avaliação genotóxica em anfíbios oriundos de um segmento de rio impactado por atividades de mineração de ferro em Minas Gerais (MG)

Abstract

Areas with mining activities are subject to contamination in aquatic and terrestrial environments, in addition to the risk of disasters, such as the collapse of the dam in Brumadinho (MG) in 2019, which is why constant monitoring of these areas is essential. The present study aimed to evaluate the genotoxic potential in anuran blood cells on the banks of the Paraopeba River, after this disaster. 349 amphibians from 8 different species were evaluated (Leptodactylus luctator, Leptodactylus fuscus, Rhinella diptycha, Rhinella gr. crucifer, Boana crepitans, Boana faber, Boana lundii and Scinax cf. fuscovarius). Blood material was collected and 3 slides/individual were prepared (fixed in Methanol P.A. and stained in Giemsa 5%), with 2000 cells/slide being evaluated (1000x under an optical microscope). Metals (Al, Cd, Pb, Co, Cu, Cr, Fe, Mn, Ni and Zn) were evaluated in surface sediment samples by flame atomic absorption spectrometry (FAAS) and electrothermal atomization (ETAAS). Statistical analyzes were performed in the R software using the GLM function, with the quasi-binomial family for the following variables: frequency of anomalies, distance from confluence, mass, CRC, species, sex, stage of development and metals and semimetals. The species L. luctator, R. diptycha and B. faber demonstrated a wide distribution along the river. The highest average frequency of nuclear anomalies was at the first collection point after the impacted area (9.47‰). The average concentrations (ppm) of Fe [281.64-618.19], Al [138.28 -459.51] and Mn [71.23-227.08] in the sediment were high throughout the river. The highest average concentrations for Al, Ar, Co, Cr, Cu, Ni and Zn were sampled points downstream of the dam failure. Sex was not significant in any statistical model. CRC (p ≤ 0.01) and mass (p ≤ 0.1) were significant. Cr was the only metal that was significant (p ≤ 0.05) and directly proportional to the frequency of nuclear anomalies. It is concluded that, although there is evidence of contamination by metals and semi-metals in the river, its condition as an area affected by multiple impacts, additional studies are necessary to prove the relationship of this contamination with the disaster that occurred.