Using oxygen isotopes as tracer for biological processes in the environmental phosphorus cycle
Seminar by Dr. Christian von Sperber, Geography Department, McGill University. Everyone is welcome to attend.
Phosphorus (P) is an essential nutrient for all living organisms. In the terrestrial environment, plants and microorganisms take up P as inorganic phosphate [PO43-] from the soil solution. Low [PO43-] concentrations in the soil solution often limit biological growth and crop production. On the other hand, excessive use of fertilizers can lead to an accumulation of P in soils, which can be transferred into water bodies causing the eutrophication of rivers and lakes. Too little or too much P can thus present problems and it is important to enhance our understanding of the biogeochemical mechanisms that contribute to the availability of [PO43-] in the soil solution. The most common way to quantify different biogeochemical soil P-pools is through sequential extractions, which yields operationally defined pools that are used to assess soil fertility and soil development. It is often assumed that certain pools are bioavailable, while others are not, even though P is exchanged among all pools. The oxygen isotope composition of phosphate is a useful tool to translate quantitative information on P pools into information about P availability and to trace specific biological processes of the P cycle which contribute to the availability of P. Applying this approach promises new insights into the biogeochemical cycle of P, both in agricultural and non-agricultural systems.
ABOUT THE SPEAKER
Dr. Christian von Sperber is an assistant professor in the Department of Geography at McGill University in Montreal, Canada. He completed his PhD in the Department of Environmental Systems Sciences at ETH Zurich under the supervision of Prof. Emmanuel Frossard and has worked as postdoctoral fellow in the Department of Biology at Stanford University and in the Department of Agricultural Sciences at the University of Bonn. His research focuses on the biogeochemical cycling of phosphorus in soils of agricultural and non-agricultural systems.