Mar 12, 2014 - lands, 2) petroleum and gas transport in the Gulf of Mexico, and 3) ... shore planktonic foodweb followin
Special Seminar The Secret Life of Carbon: Isotopes Reveal the Sources and Transformations of Life’s Most Abundant Element Dr. Rachel Wilson Florida State University Because of their potential to reveal both source and process information, stable isotopes are an increasingly utilized tool for tracing natural processes that are not directly observable such as 1) carbon cycling in wetlands, 2) petroleum and gas transport in the Gulf of Mexico, and 3) atmosphere-biosphere interactions in arctic peatlands. This talk will start with a brief introduction to stable isotopes and the mechanisms of fractionation that allow us to infer sources and transfer patterns in natural systems. I will demonstrate how we integrated such geochemical analyses with seismic profiles to determine the sources, migration, and fate of hydrocarbon seepage at a natural gas-hydrate mound in the Gulf of Mexico. This work has applications to understanding the extent and distribution of a potentially large global natural gas reservoir and, with the incorporation of radiocarbon analyses, allowed us to track the introduction of methane and oil into the offshore planktonic foodweb following the 2010 Deepwater Horizon oilspill. Next, I will describe the development and application of stable isotope mixing models within an ecological context and show how we applied such a model to quantify the contribution of terrestrial organic matter within a freshwaterdominated estuary where water-rights and allocation of water resources has been a hotly contested issue. Expanding on this work, I will demonstrate how stable isotopes in combination with organic pollutant analyses have been applied to define dolphin foraging habitats in an effort to understand why bottlenose dolphins in the northern Gulf of Mexico seem exceptionally vulnerable to the toxins produced during harmful algal blooms. Finally, I will discuss how combining stable isotope analysis with other biogeochemical indicators allows us to infer net changes in the carbon footprint of permafrost and peatland systems under a warming climate scenario and how this work will enhance current models of global carbon cycling.
