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Land reclamation and mine closure are the final steps of the mining process. They are also often considered the longest and most complex phase. Reclaimed mine sites undergo routine environmental assessment to ensure disturbed ecosystems are progressing toward recovery targets. However, it can take years to see the first signs of recovery using traditional observational methods, like assessing vegetation cover. As a result, scientists are exploring the use of environmental DNA (eDNA) to assess early reclamation progress by examining the biodiversity of microbes, fungal communities and insects before vegetation growth.

Thompson Rivers University researchers expanded upon a previous Genome BC funded project, which developed a metagenome sequencing method to assess the long-term impacts of biosolids on soil microbial communities during mine reclamation (UPP022). However, they realized that the presence of relic DNA could affect microbial diversity measurements at biosolid-treated mine sites. Relic DNA is extracellular DNA from dead microorganisms that can persist in biosolids for years and account for up to 80% of the total microbial DNA pool in the soil.  In this AMENDS project, the researchers developed a method – a standardized eDNA protocol – to analyze DNA from only living microorganisms. They found that including one extra pretreatment step, adding the chemical propidium monoazide, to the standard eDNA protocol improved the evaluation of microbial and fungal diversity. They also discovered that the older the cleaned-up mine was, the greater the diversity of microbes and fungi. This supports the use of eDNA as the signature of ecosystem recovery   and suggests that eDNA sampling can help determine if mine cleanup efforts are working early on, potentially reducing reclamation costs and adding confidence in regulatory compliance during mine reclamation and closure.