REsearch In Environmental Geosciences

There is a critical need to reduce greenhouse gas (GHG) emissions to limit the impacts of global climate change.  Moreover, carbon pricing systems are providing growing financial incentives to implement GHG-cutting technologies.  This places stress on Canada’s energy intensive, resource-based economy.  The long-term goal of our research is to elucidate fundamental geochemical, mineralogical, and geobiological processes relating to CO2 mineralization, which is a promising carbon sequestration strategy that involves the reaction of a feedstock with carbon dioxide to form stable carbonate minerals.  

I conduct field studies and laboratory experiments supplemented with geochemical modelling to examine mineral-water-microbe interactions while seeking opportunities for industrial application.  Our work has made significant advances for better understanding carbonate mineral formation in the critical zone, microbial and enzyme-mediated carbonation, mineral weathering and bioleaching, and mine waste carbonation at Earth’s surface conditions. 

 

Mine wastes at the Clinton Creek chrysotile mine have sequestered over 100,000 tonnes of carbon dioxide through natural weathering processes.

Tailings management and Co2 sequestration

Mine waste (e.g., tailings) generation is escalating as the demand for resources increases and high-grade ore deposits become scarce.  Consequently, the mining industry must develop more secure and cost-effective tailings management practices while improving environmental performance such as reducing GHG emissions.  Alkaline, ultramafic and mafic (Mg-rich) mine wastes react spontaneously with atmospheric CO2 to precipitate carbonate minerals, thereby securely storing CO2.

Management and containment of mine tailings represent a considerable cost and risk in mine operations because of the potentially harmful environmental impacts of tailings and the possibility of an accidental release.  In addition to sequestering CO2, carbonation of mine wastes has the potential to cement tailings to increase stability, reduce dust and sequester toxic metals.  Ongoing research is examining how carbon sequestration and other benefits can be combined and accelerated, which offers enticing possibilities for the mining industry. 

Natural analogues for carbon sequestration

Insights into CO2 mineralization of ultramafic materials are gained by studying natural analogues such as the ultramafic complex (i.e., peridotite) near Atlin, British Columbia, Canada.  Weathering of the Atlin peridotite over millennia has led to substantial deposition of Mg-carbonates within playa environments.

Formation of secondary Mg-carbonate is intrinsically linked to the availability of Mg.  The Atlin peridotite has been partly altered by aqueous and CO2-bearing hydrothermal fluids to serpentinite and quartz-magnesite (listvenite) rocks prior to the formation of the playas.    

Reaction pathways of carbonate formation have recently gained greater attention because of their relevance to permanent storage of CO2 in ex situ carbon mineralization processes and deep geologic storage.  The Atlin playas host an array of carbonate minerals, most notably magnesite (MgCO3), which is an ideal sink for CO2 because it is the most stable form of Mg-carbonate.  Current research is examining mechanisms and rates of magnesite formation.  

Hydromagnesite-magnesite playas are a unique Mg-carbonate forming environment and a natural analogue for carbon storage.  Monarch Mountain in the background is composed primarily of serpentinized harzburgite, i.e., ancient oceanic crust.

Carbonated microbial mat from the wetlands in the hydromagnesite-magnesite playas.  Minerals include nesquehonite, dypingite and aragonite.

Geobiological approaches to carbon management

Geobiological processes have a profound impact on Earth’s carbon cycle and may be exploited for sequestering CO2.  Microbes have contributed extensively to carbonate precipitation within oceans, lakes, springs, caves, and soils over geologic time.  We have demonstrated the roles cyanobacteria and algae play in inducing precipitation of Mg-carbonate minerals, a long-term sink for CO2.  These phototrophs can dramatically alter their microenvironments relative to bulk water chemistry such that carbonate precipitation is induced.  For instance, microbial cell walls can adsorb cations, increasing their local concentration, while CO2 concentrating mechanisms employed during photosynthesis result in alkalization; both of these processes drive carbonate formation.  

 

Recruiting students for B.Sc., M.Sc., and Ph.D. theses!

Interested in joining the team?  Please email Dr. Power (ianpower@trentu.ca) providing a cover letter describing your qualifications, resumé, and unofficial transcripts.  All qualified and interested students are welcome!