Quantifying ecosystem methane emissions from subtropical pasturesSubtropical pastures are a major global land use, however little is known about the magnitude and patterns of pasture methane emissions during periods of fooding. We investigated the controls and patterns of pasture methane fluxes using a combination of eddy covariance, experimental manipulations, and spatial flux measurement techniques.
This work demonstrated that subtropical pastures are strong yet variable methane sources, on the order of tropical wetlands, and cattle are responsible for only 19-30% of annual emissions (Chamberlain et al. 2015). Additionally, flux patterns were driven by rainfall oxygen dynamics and flooding of organic surface soils, which exhibited orders of magnitude higher methane production rates than deeper mineral soil horizons (Chamberlain et al. 2016). These results suggest that relatively small changes in pasture flooding may drive large changes in net greenhouse gas emissions. However, we found that water retention practices, aimed at reducing nutrient loading to the Everglades, do not increase methane emissions to a significant degree (Chamberlain et al. 2017). The above work was in collaboration with the MacArthur Agro-ecology Research Center, Cornell University, and University of Illinois at Urbana-Champaign. |
Sourcing methane and carbon dioxide emissions from Ithaca, New YorkNatural gas leakage and combustion are major sources of methane and carbon dioxide, however our understanding of emissions from cities is limited. I quantified natural gas emission patterns in Ithaca, New York using a mobile methane detection system and continuous atmospheric measurements of carbon dioxide and methane concentrations and isotopes. Our work demonstrated that natural gas leakage rates from distribution pipelines is low, likely due to the small extent cast-iron pipelines within the Ithaca system, and also showed that centralized natural gas combustion facilities may be an important greenhouse gas emissions source when pipelines are well-maintained (Chamberlain et al. 2016). This work was collaborative between the Sparks’ lab and Dr. Anthony Ingraffea in Cornell’s School of Civil and Environmental Engineering.
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