Understanding the Environmental Impact of a Mine Dam Rupture in Brazil: Prospects for Remediation

The rupture of the Fundão mine dam in Mariana municipality, Minas Gerais State, Brazil, spilled the tailings across the Doce River basin. These tailings, composed of residues discarded from the beneficiation of iron ore, are rich in SiO and AlO, as well as some ether amine compounds and NaOH. The aim of this study was to assess the distribution of these sediments, as well as their effect on the riparian zones reached, as compared with preserved sites. Sediment deposition in the river resulted in a morphological change from a meandering profile to a braided aspect. The nutrient and mineral content (P, K, Ca, Mg, Cu, Fe, Mn, Zn, and NO) and soil organic matter of the sediments were depleted, whereas NH, Na, and pH increased. A random presence of ether amines in the sediments was confirmed by quantitative and chromatographic analyses, with concentrations ranging from 0 to 57.8 mg kg; Na reached values as high as 150 mg kg. The impact of the dam tailings on biota was assessed by estimating total microbial biomass (phospholipid fatty acids), which were depleted in sediments relative to soils from preserved sites. Overall plant mortality, as well as a low resilience capacity, were also observed. Ether amines and Na present in the sediments had a strong toxic effect in the environment. Identification of these substances as the main impact factors will help guide future remediation efforts.

Antifungal activity of Brazilian medicinal plants involved in popular treatment of mycoses

A survey of medicinal plants used to treat common mycoses was done in the Curituba district, Sergipe State, Brazil. One hundred inhabitants were interviewed by health agents and traditional healers. Four different plants were the most cited (more than 50% of the citations): Ziziphus joazeiro, Caesalpinia pyramidalis, Bumelia sartorum and Hymenea courbaril. The aqueous extracts obtained following traditional methods and using different parts of these plants, were submitted to drop agar diffusion tests for primary antimicrobial screening. Only the water infusion extract of Ziziphus joazeiro and Caesalpinea pyramidalis presented a significant antifungal activity against Trichophyton rubrum, Candida guilliermondii, Candida albicans, Cryptococcus neoformans and Fonsecaea pedrosoi, when compared to the antifungal agent amphotericin B. The minimal inhibitory concentration (MIC) of the bioactive extracts was evaluated by the microdilution method. Best activity with a MIC of 6.5 microg/ml for both extracts was observed against Trichophyton rubrum and Candida guilliermondii. Ziziphus joazeiro and Caesalpinea pyramidalis extracts presented also low acute toxicity in murine models. The present study validates the folk use of these plant extracts and indicates that they can be effective potential candidates for the development of new strategies to treat fungal infections.