Citotoxicidade e genotoxicidade da água e sedimentos do Rio Doce na cidade de Governador Valadares - MG

Abstract

After the environmental disaster caused by the collapse of the Fundão dam, in Minas Gerais (MG), ore waste was dumped into the Doce River, impacting water quality, ecosystems and local communities. This work aimed to evaluate the cytotoxic and genotoxic potential of water and sediment samples from the Doce River through bioassay with Allium cepa, which allows an analysis of the toxic potential of components in the water based on their effect on plant cells. Raw water and sediment samples were collected in different locations and periods of the year, in the Governador Valadares region, for macroscopic and microscopic analysis of A. cepa roots. The physicochemical analysis revealed pH values below normal limits, while conductivity and turbidity were adequate. Among the sediments, only the magnetic fraction showed cytotoxicity and genotoxicity, evidenced by the reduction in the mitotic index and micronuclei formation, respectively. In contrast, raw water samples showed no changes in the parameters evaluated, except for a significant increase in root growth. No significant differences related to seasonality or collection location were identified. The results suggest that, although the waters of the Doce River do not present acute or chronic toxicity, the magnetic fraction of the sediments has a toxic potential, which may represent long-term environmental risks. Therefore, new studies and continuous monitoring are recommended to assess the impacts of these sediments and guarantee the water quality of the region.