|CAMBALIZA, MARIA - Purdue University|
|BOGNER, JEAN - University Of Illinois|
|GREEN, ROGER - Waste Management, Inc|
|SHEPSON, PAUL - Purdue University|
|HARVEY, TIERNEY - Duke University|
|BRIAN, STIRM - Purdue University|
|MARGARET, CORCORAN - University Of Illinois|
Submitted to: Elementa: Science of the Anthropocene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2017
Publication Date: 7/4/2017
Citation: Cambaliza, M.O., Bogner, J., Green, R.B., Shepson, P.B., Harvey, T.A., Spokas, K.A., Brian, S.H., Margaret, C. 2017. Field measurements and modeling to resolve m2 to km2 CH4 emissions for a complex urban source: An Indiana landfill study. Elementa: Science of the Anthropocene. 5:36.
Interpretive Summary: This article describes the recent evaluation of large and small scale emission measurements along with mathematical modeling to describe a methane source area. To accomplish this we compared the results from four field methods, which were aircraft-based mass balance, tracer correlation (plume monitoring), vertical radial plume mapping, and static surface chambers. These results were then compared to that of a theoretical gas transport model (California Landfill Methane Inventory Model, CALMIM 5.4). Through this work, we were able to visualize the heterogeneity of the emission area. The model results compare very favorably with actual site emission measurements. This work demonstrates the need to utilize multiple field measurements and models that account for an entire annual cycle when forecasting GHG emissions from a particular site or operation. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved models for predicting net greenhouse gas emissions. These types of annual tools will be critical for improving soil carbon management.
Technical Abstract: Large uncertainties for landfill CH4 emissions due to spatial and temporal variabilities remain unresolved by short-term field campaigns and historic GHG inventory models. Using four field methods (aircraft-based mass balance, tracer correlation, vertical radial plume mapping, and static chambers) and a new field-validated process-based model (California Landfill Methane Inventory Model, CALMIM 5.4), we investigated the total emissions from a central Indiana landfill as well as the partitioned emissions inclusive of methanotrophic oxidation for the various cover soils at the site. We observed close agreement between whole site emissions derived from the tracer correlation (8 to 13 mol s-1) and the aircraft mass balance approaches (7 and 17 mol s-1) and statistically indistinguishable from the modeling result (10 to 15 mol s-1). Our model calculations indicate that the small area for daily operations (daily cover area) overlying older methanogenic waste is the largest contributor to the total site emissions, which must be verified in future studies. This landfill is an upwind source for Indianapolis, USA, so the resolution of m2 to km2 scale emissions as well as understanding the temporal variability, contributes to improved regional inventories relevant for addressing mitigation strategies.