About this Research Topic
Metalliferous mining activities generate massive quantities of solid waste across the globe. Solid mine wastes include both tailings that remain after ore extraction and waste rock comprised of materials with metal concentrations too low for economic extraction. Revegetation of these extensive mine waste stockpiles is impeded on decadal time scales due to multiple factors including extremely acidic or alkaline pH, low nutrient content, elevated concentrations of metals, metalloids and inorganic compounds, poor water-holding capacity (either too high in the case of tailings, or too low in the case of waste rock), poor substrate structure, and limited microbial nutrient cycling and plant growth-promoting capacity. In the absence of a vegetative or other cover, mine tailings are highly prone to eolian dispersion and water erosion processes with potential to create negative impacts on neighboring communities and ecosystems.
Reclamation efforts promote transformation of mine wastes into materials with chemical, physical, and biological properties closer to those of naturally developed soils. This is beneficial regardless of the intended end land use, which often involves the establishment of a sustainable vegetation cover to stabilize the tailings (phytostabilization). Microbial communities can play key roles in this transformation, both in modifying the properties of mine wastes to more closely resemble natural soils, and in optimizing plant nutrition and survival. For example, the weathering and oxidation of tailings from pyrite-rich ore deposits is accelerated by iron- and sulfur-oxidizing autotrophic microbial populations that drive acidification which in turn inhibits plant growth. The inhibition of autotrophic oxidizers and restoration of organotrophic nutrient cycling microbial populations is critical to plant establishment on these pyritic materials, limiting further acidification and improving nutrient availability while also improving structure. Even under more benign geochemical conditions, mine tailings and waste rock represent infertile and biologically depauperate incipient soils with limited potential to support plant establishment.
The future sustainability of metal mining is dependent on technological advances that facilitate ecosystem regeneration of the large land areas disturbed by mine tailings and waste rock deposition. This research topic is focused on understanding the microbial ecology and associated ecosystem services that define diverse categories of mine waste materials and developing potential rehabilitation strategies that accelerate the microbially-driven transformation of these mine wastes.
Microbial transformation includes development of the nutrient cycling capacity critical to sustain vegetation establishment.
Articles are invited that address 1) the phylogenetic structure, activity and ecological function of microbial communities colonizing acidic, alkaline or neutral mine tailings or waste rock stockpiles; 2) transformations in both the microbial community function and composition that associate with sustainable vegetation establishment; 3) the response of microbial community structure and associated functional capacity to different reclamation strategies; and 4) evaluation of the use of microbial inputs that accelerate the rehabilitation process either in situ or as part of bioreactors.
Keywords: Mine tailings, reclamation, microbial ecology, plant-growth-promoting bacteria, phytostabilization, microbial biotechnology
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.