PARENT SESSION
Symposium 1: In the Footsteps of Lewis and Clark: Rediscovering Earth From Land to Sea - A Biogeoscience Perspective.
Organized by: PV Sundareshwar and J Elser
Monday, August 2, 8:00 AM to 11:30 AM, Oregon Ballroom 202.

Phosphorus transformations in ecosystems.

Richardson, Curtis^*,,

ABSTRACT- Phosphorus transformations are controlled by both biotic and abiotic mechanisms but comparisons of factors controlling transformations among ecosystems have not been done. Long-term phosphorus (P) storage is often related directly to the amount of P stored as mineral bound inorganic Pi or as organic P (Po) in soils or biomass. However, little information is available on the proportion of Po that is available to organisms within the ecosystem or the amount of Po that is exported as dissolved organic P (DOP). Moreover, the operational definition of Po is unclear since we often refer to it as TOP, FOP, or POP. A comparative analysis of the fractionation techniques often used to quantify the forms of P in terrestrial, and wetland soils and aquatic sediments will be compared to the use of 31P-NMR as a technique to refine Po estimates. The concept of P limitation will also be assessed by comparisons of N: P molar ratios among ecosystems.

Key words: transformations, organic phosphorus, 31-P NMR