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.  The overarching goal of our research is to elucidate fundamental geochemical, mineralogical, and geobiological processes related to CO2 sequestration and management.  We 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.  Interested in joining the team?  Please email Dr. Power (ianpower@trentu.ca) about your research interests.  All qualified and interested students are welcome! 

 

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

Co2 sequestration at Mine sites and Enhanced weathering

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 (e.g., Power et al., 2014). Furthermore, mining environments are ideal localities to study enhanced weathering as a means of carbon dioxide removal from the atmosphere.

Currently, we are most active in South Africa where we are planning on launching pilot projects to assess strategies to accelerate CO2 mineralization within mine wastes from diamond mines.

Current projects: 1) CO2 mineralization within mine wastes at diamond mines, and 2) Reactivity of mine wastes and enhanced weathering. Graduate theses projects available.

Natural analogues for carbon sequestration

Insights into carbon sequestration of ultramafic materials are gained by studying natural analogues such as the ultramafic complex (i.e., peridotite) near Atlin, British Columbia, Canada (Power et al., 2009).  Weathering of the Atlin peridotite over millennia has led to substantial deposition of Mg-carbonates within playa environments (Power et al., 2014). 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 (Power et al., 2017).  We are exploring mechanisms that lead to the formation of magnesite within the Atlin playas.

Current projects: 1) Mechanisms of magnesite formation. Graduate theses projects available.

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 of heterotrophic and phototrophic bacteria in facilitating precipitation of carbonate minerals, a long-term sink for CO2 (e.g., Power et al., 2007; 2011).  These processes can be utilized in mining environments. 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 can be accelerated by bacteria and how biocementation can improve tailings stability.

Current projects: 1) Biocementation of mine tailings for improving stability.  Graduate theses projects available.