The University of British Columbia

Food insecurity and risks associated with projected global changes are serious global issues that must be addressed. The soil is a “bio-reactor” playing a leading role in global change processes because of its position at the interface of the atmosphere, biosphere, hydrosphere and lithosphere. The soil organic carbon (SOC) reservoir is the largest terrestrial carbon pool and plays a significant role in the control of greenhouse gas emissions as well as soil fertility, plant productivity and the retention of pollutants. It is therefore critical to address some of the current environmental challenges by tackling the mechanisms of SOC stabilization in soil and their regulating factors, all still poorly understood. The activity of metals in soil solution and secondary clay minerals (amorphous components, poorly-crystalline aluminosilicates and hydroxyl-bearing phases) are the most important for long term SOC stabilization. Therefore, we will focus on quantifying the origin and rate of formation of the secondary soil phases using modern geochemical tools such as stable silicon (Si) isotopes, trace elements (germanium, Ge) and Rare Earth Elements (REEs) concentrations and ratios. The PCIGR analytical facility significantly expanded in 2011 because of a successful CFI LEF grant ($7.5 million) and will acquire, among others, a Nu 1700 high-resolution MC-ICP-MS, the highest performing instrument for the isotopic analyses that we want to carry out.  During postdoctoral researches, we aim to respond to three questions: (1) What are the main mechanisms that control the formation (origin) of secondary minerals with high capacity to stabilize SOC?; (2) What is the effect of the rate of formation of these secondary minerals on SOC stabilization?; and (3) How can we improve future SOC stabilization capacity in the Earth’s critical zone and evaluate its evolution with climate, hydrological and land use management changes?

The more significant contributions of my research to date may be summarized as follows:

Soil sciences

• Impact of tree species on the soil development and properties

• Organic matter decomposition

• Interdependent relationship between soil formation and stabilization of soil organic carbon

• Amorphous and poorly crystalline secondary minerals

Biogeochemistry

• Biogeochemical cycles in temperate and tropical forest ecosystems

• Silicon (Si) dynamics in soil-plant systems

• Geochemical tracers (stable Si isotopes and Ge/Si ratios) and the Si pathways in terrestrial ecosystems