Keywords: zinc mines, mine spoil dumps, FYM, farmyard manure, Azotobacter, Rhizobium, VAM, vesicular arbuscular mycorrhizae, phytoremediation, ecological restoration, bioremediation, revegetation, vegetation, mine overburden, site contamination, microbes, mining
Microbe-assisted phytoremediation approach for ecological restoration of zinc mine spoil dump
Mining is one of the sectors that impacts air, water and soil pollution. The various environmental problems that are associated with mining activities are deforestation, removal of fertile topsoil, unstable slopes prone to sliding and erosion, siltation of water bodies due to wash off of mineral overburden dumps, air pollution due to discharge of dust and noise pollution. The most effective means of reducing the impact of such potential hazards is rapid revegetation. Revegetation accelerates soil formation, leading to establishment of a stable ecosystem and combats the different problems. The reclamation of mine overburden is intimately associated with the recovery of a stable microbial processes and communities resembling that of a natural soil. To revegetate such eco-vulnerable system, an eco-friendly and cost-effective 'microbe-assisted phytoremediation approach' adopted to restore the nature's pattern of stable and diverse ecosystem on zinc mine spoil dumps. The approach involves isolation and inoculation of site-specific specialised nitrogen-fixing strains of Bradyrhizobium and Azotobacter species, nutrient mobilising vesicular arbuscular mycorrhizal spores of Glomus and Gigaspora sp., selection of suitable plant species (preferable multispecies) and suitable organic amendments. The results indicate that the approach restored the productivity, fertility and stability of zinc mine spoil leading to the development of sustainable ecosystem thereby mitigating the environmental hazards and improving the environmental health of the nearby contaminated sites. Microbe-assisted phytoremediation approach stabilises the negative effects of zinc mine spoil dumps rapidly within a short span of time (2?3 years) in a cost-effective way.