Reclaiming Mining Lands in Southern Arizona: A Scientific and Policy Inquiry towards Resiliency

Abstract

Copper is critical to the sustainability of the modern lifestyle; however, mining creates massive land disturbance and generates large quantities of unstable waste materials that need to be managed for the long-term environmental and public health of neighboring communities (Lima et al., 2016). One waste challenge associated with modern mining is managing mine tailings. Mine tailing reclamation is site specific but often has a long-term goal towards ecological restoration and is impacted by stakeholder and rights holder associations (i.e. private, government or tribal) (Keller et al, 2011). Mine waste reclamation aims to stabilize waste to support self-sustaining plant communities. A critical limitation to vegetation success in mining waste is that these “soils” are deficient of the microbial communities and nutrients necessary to support plant establishment. The costs associated with these restoration activities can also be substantial, and vary with mine size, regulatory regimes, technology, presence of legacy reclamation costs, or cultural resources within the area (Mudd, 2009). Long-term ecological management of mine waste is an essential and problematic component of efficient mine site reclamation throughout the Southwest. Soil health properties essential to successful phytostabilization of reclaimed mine sites are poorly understood. This study found that total nitrogen and DNA biomass show promise as potential indicators of soil fertility that correlate with revegetation improvement. Our studies suggest that capping material source significantly influences the rate of plant establishment. Quantitative metrics must be further investigated to improve methods for screening potential capping material sources for mine tailings reclamation. Longer term studies are needed, particularly for mine recovery in the Southwest, where plants grow slower. Future work should consider how below ground fertility metrics reflect ecosystem stability and plant structure, and how the quality and application method of soil capping may impact future plant community structure.