Abstract
The reclamation of mine waste deposits is often hindered by the scarcity of natural topsoil. Acid mine drainage sludge (AMDS), as a mass-produced waste in metalliferous mines, is a potential topsoil substitute but had not been validated. In this study, a pot experiment with three plant species was conducted to evaluate the capacity of AMDS to support plant growth, buffer acidification, and immobilize heavy metal(loid)s when reclaiming mine waste rocks. Chemical fertilizer and compost chicken manure were applied to AMDS at different rates to explore their effects on plant growth and the physicochemical properties of AMDS. Results showed that all the plants could survive in AMDS even without fertilization. The contents of heavy metal(loid)s in rhizosphere remained almost unchanged over the experimental period, indicating low leachability of revegetated AMDS. Fertilizers enhanced macronutrients and soil enzyme activities, leading to significant increases in plant biomass. However, owing to manure composting and low richness and diversity of the bacterial community in AMDS, the NH4+-N and bioavailable phosphorus contents were extremely low. Bermuda grass was a suitable pioneer species for reclamation for its better adaptability to nutrient deficiency and heavy metal(loid) stress. Overall, AMDS is a viable soil substitute for mine reclamation due to its capability to support plant growth and environmental safety.
Highlights
Tailings and waste rocks are produced in large quantities in mining process (Park et al 2019)
The present study clearly indicated that Acid mine drainage sludge (AMDS) could be used as a viable substitute for natural soil in the revegetation and reclamation of mine waste deposits
All the plants, including alfalfa, Bermuda grass and broad-leaved paspalum survived in the AMDS, especially when fertilizers were applied (Fig. 1)
Summary
Tailings and waste rocks are produced in large quantities in mining process (Park et al 2019). In China, there were 9656 tailing ponds and 57791 solid waste dumps, and the existing tailings and solid wastes amounted to more than 20 and 60 billion tons, respectively, according to a survey in 2015 (Wang and Xue, 2017). Borrowed topsoil varied in quality and usually required further amendment (Chu and Bradshaw, 1996) In this context, materials which possessed similar edaphic properties to natural soil began to be used as topsoil substitutes in the reclamation of mine waste deposits (Gorman et al 2000; Dayton and Basta, 2001)
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