Strategy for phytomanagement in an area affected by iron ore dam rupture: A study case in Minas Gerais State, Brazil.

In 2015, the Fundão tailing dam collapsed over the district of Bento Rodrigues (Mariana, Minas Gerais, Brazil) causing deaths, hundreds of homeless families and incalculable environmental degradation. Environmentally, economically and socially sustainable strategies are needed for the recovery of the affected areas. The main goal of this study was to evaluate the development, biomass production and toxic mineral elements absorption of three species of aromatic grasses (Chrysopogon zizanioides, Cymbopogon citratus and Cymbopogon winterianus). These three species were planted on polypropylene pots filled with the iron ore tailings collected from the topsoil of the Bento Rodrigues district. The pots were fertilized with increasing doses of organic compost associated with mycorrhizae as a phytomanagement strategy. A 4 × 2 factorial scheme was used. The seedlings were fertilized with four doses of organic compost, with or without mycorrhizae. At the highest dose of the organic compost (2 kg.plant-1), the total dry matter (dry matter of the aerial part + dry matter of the roots) for C. zizanioides was 4.5 times higher than the control (tailing only). For C. winterianus and C. Citratus was 3.8 and 2.8 times higher than the control, respectively. Inoculation with mycorrhizae improved biomass production, especially in C. zizanioides. The Fe and Mn levels found in the aerial part of the plants fertilized with organic compost were lower than those just growing on the iron ore tailings for the three species, which suggest that the organic matter apparently helped the plants in the exclusion of the hazardous substances and therefore increased the tolerance to these adverse environmental conditions. C. zizanioides, associated with organic matter and mycorrhizae, would be the recommended species. The proposed phytomanagement strategy can have a significant contribution to the gradual recovery of the affected area and also serve as a source of income for the local population.

Copper phytoremediation potential of wild plant species growing in the mine polluted areas of Armenia.

Nowadays the pollution of soil by trace metals from the mining industry is one of the biggest threats to ecosystems and human health. In this study, sixteen native wild plant species growing in Cu contaminated soils of mining region in Armenia were investigated to reveal their phytoremediation potential for restoration of soils in this area. During the investigation soil main characteristics affecting the Cu accumulation capability of plants were also determined. In roots (dry weight) of dominant plant species growing in Cu contaminated areas the content of copper varied between 55 mg/kg (Hypericum perforatum) and 775 mg/kg (Thymus kotschyanus), and in shoots of plants - in the range from 33 mg/kg (Teucrium orientale) to 243 mg/kg (Phleum pratense). Since the Cu accumulation capability of plants depends both on physiological peculiarities of plants and on the content of Cubioavailable in the soil, the studies were carried out in this direction and it was found that the high contents of organic matter and clay in the soil facilitated the decrease of the ratio Cubioavailable/Cutotal and as a result - the decrease of Cu accumulation capability of plants. Thymus kotschyanus, Phleum pratense, and Achillea millefolium had the highest phytostabilization potential from all studied plant species due to high bioconcentration factor of root (BCFroot) and low translocation factor (TF) values registered in these plants, and further field and laboratory experiments are planned to confirm this useful ability. The detection of phytoremediation potential of wild plant species growing in areas polluted by trace metals will enable us to use eco-friendly and cost-effective remediation methods, utterly required to clean up the soils in the mining regions of Armenia.