Stabilization of hard rock mines tailings with organic amendments: Pore water quality control and revegetation – A review

Abstract

Organic amendments aided with vegetation are considered a promising prevention approach for the stabilization of metal-contaminated tailings. However, the inconsistency in the performance of different amendments and their effects on plants growth indicate that further studies are still required. To better select the appropriate organic amendments and identify future research avenues for mine tailings stabilization, this critical review makes a preliminary compilation of available knowledge on organic amendments and their reported performance. To this end, data were collected from several review papers and case studies, with a particular focus on the evolution of pore water quality and plant phytostabilization abilities. The screening of the most promising materials was then carried out according to whether metallic elements were mobilized/immobilized from pore water, sequestered into rhizosphere or plant aboveground parts. Results showed that mixture of organic and inorganic materials are more efficient than organics alone. Amendments combining mature and composted animal manures with inorganic materials would be more promising. Conversely, fresh compost and biosolids could enhance metals release in pore water and, possibly, the transfer in plants aerial parts. Finally, biochars could be efficient if mixed with raw organic amendments but the effect on vegetation still needs to be evaluated. Further studies should focus on amendment-plant-microbes interactions and the long-term stability of organic amendments (>10-20 years).