Ecosystem function in alluvial tailings after biosolids and lime addition.

Area of Science:

• Environmental Science
• Soil Science
• Ecology

Background:

• Mine tailings pose significant environmental challenges due to high acidity and metal contamination.
• Restoring ecosystem function in such sites is crucial for environmental remediation and land reclamation.

Purpose of the Study:

• To evaluate the effectiveness of municipal biosolids and agricultural limestone in restoring ecosystem function of acidic, metal-contaminated mine tailings.
• To assess the long-term impacts of amendments on soil chemistry, microbial activity, and the survival and health of introduced organisms.

Main Methods:

• Incorporation of biosolids and limestone into mine tailings, followed by seeding and plant establishment.
• Measurement of chemical (Pb, Zn, Cd, NO3-) and biological (CO2, N2O evolution) parameters over time.
• Assessment of ryegrass and earthworm survival, metal uptake, plant diversity, small mammal exposure, and aquatic organism toxicity.

Main Results:

• Amendments significantly decreased extractable Pb, Zn, and Cd in tailings.
• Increased CO2 evolution and NO3- levels indicated enhanced microbial community activity compared to controls.
• Ryegrass and earthworm survival in amended tailings matched laboratory controls, while unamended tailings were lethal.
• Small mammal and aquatic toxicity studies showed low risk associated with amended tailings.

Conclusions:

• Biosolid and limestone amendments effectively restored key ecosystem functions in metal-contaminated mine tailings.
• While significant progress was made, the amended tailings ecosystems have not yet reached full equilibrium.
• The study demonstrates a viable strategy for the ecological reclamation of severely degraded mine sites.