Additions of Physical and Biogeochemical Tracers to Wetland Soils Can Reveal Mechanisms Underlying the Productivity-Methane Emission Relationship

Colorado State University, Fort Collins CO

Investigators

Abstract

Methane is an important greenhouse gas that is primarily emitted from wetlands. Among the greatest uncertainties in climate change science is the degree to which global warming may alter the soil processes that lead to methane emission. Because it is inherently difficult to directly observe the plant and microbial processes that govern methane emission rates, scientists have depended on indirect evidence (laboratory or other snapshot measures on highly disturbed samples) to predict future methane emissions. We will, for the first time, make direct, long-term field measurements of methane production, consumption and transport, the three processes that proximately regulate methane emission, and relate those processes to their broader-scale controls. The novelty of our work derives from use of a suite of inert and biological tracers to measure soil processes over weeks or months without disturbing the system. We will measure methane production and consumption by releasing methane that has been labeled (as a non-radioactive isotope) into wetland soils and subsequently monitoring the relative abundance of that label. To account for non-biological loss of the label due to transport to the atmosphere or dilution by flowing water in the wetland, we co-add an inert gas and a hydrologic tracer. Interestingly, we will be the first to measure water flow using individually-labeled nanospheres, constructed at Cornell University's nanofabrication facility.