The rates and mechanisms of weathering processes are important to understanding a variety of environmentally and economically important issues including the (bio)geochemical cycling of mineral nutrients, the evolution of landforms, and the long-term drawdown of atmospheric CO2. Most weathering occurs within the “critical zone”, which is the external layer of the terrestrial Earth from the vegetation canopy to fractured bedrock. This zone sustains most terrestrial life on the planet, yet natural and human-related processes perturb and threaten the critical zone worldwide. Undoubtedly, the most significant aspect of weathering is the breakdown of rocks to form soils, a process that creates the critical zone and makes life possible on the surface of the Earth. The overarching goal of “critical zone research” is to understand how the outer envelope of the terrestrial earth functions as a whole, how it is formed and maintained on the landscape, what will happen to it in the face of environmental changes, and how its processes impact (bio)geochemical cycles and fluxes on local and global scales.

My expertise is in low-temperature geochemistry and biogeochemistry with a focus on weathering and mineral nutrient cycling in soils. Specific research goals include resolving rates of mineral weathering and soil formation and quantifying feedbacks between weathering, erosion, and biology in the critical zone. In addition, the extreme complexity of the critical zone gives rise to the need to identify how spatial and temporal heterogeneity in physical, geochemical and biological properties impacts critical zone mineral nutrient cycles. Finally, the ability to make full use of emerging isotopic proxies for paleoclimate studies and reconstructions of past nutrient fluxes requires an understanding of the (bio)geochemical fractionation mechanisms that affect the isotopic signatures in the critical zone. Thus a primary research focus is the identification and quantification of the processes that establish the isotopic signatures that are exported from watersheds.