Dissertation Research: Anaerobic Methane Oxidation in Freshwater Wetlands

Cornell Univ - State: Awds Made Prior May 2010, Ithaca NY

Investigators

Abstract

Methane is a natural component of the earth's atmosphere. However, the increase in the concentration of atmospheric methane since the turn of the century is a likely contributor to the enhancement of the greenhouse effect. A significant portion of atmospheric methane comes from freshwater wetlands where microorganisms produce methane in oxygen depleted soil. It is known that microorganisms living in the oxygenated part of the soil can consume some of the methane produced, so that the amount of methane leaking to the atmosphere is the difference between production and consumption. It is also possible that this methane consumption can occur in the oxygen depleted zone of the soil, yet this process is poorly understood. Most evidence for this process comes from sediments beneath the ocean, yet I have found strong evidence that large amounts of methane also can be consumed by microorganisms in the oxygen poor soil of a freshwater wetland in central New York State. The process is elusive and linked to seasonal climate patterns, which may be why the process was not seen by earlier investigators. This proposal requests funds to examine the extent of the process in peatlands in central New York State, Maryland, West Virginia, and Sweden. These are all well studied sites where the process would be expected to occur. Primary objectives are to assess the role of microorganisms that use iron instead of oxygen to consume methane, and how iron availability might limit the process. Results of this study should provide valuable insight into the relationship between atmospheric methane and wetland methane emissions. Moreover, a mechanistic understanding of methane emissions is essential in order to predict how methane emissions from wetlands will respond to future environmental changes.