Werts, Scott (Johns Hopkins Univ., Department of Earth and Planetary Sciences, 113 Olin Hall, 2400 N. Charles St., Baltimore, MD, 21218; Phone: 410-516-7521; Fax: 410-516-7933; Email: swerts@jhu.edu)

Determining Amounts of Carbon Loss and Change in Carbon Isotope Values from Soils Due to Biomass Burning

S.P.Werts *, A.H.Jahren

Quantifying carbon emissions from the burning of above ground biomass has long been studied and considered a major source of greenhouse gases to the atmosphere. In most studies, however, carbon emissions from soil due to these burning events is not considered even though these soils often contain three times the amount of carbon as the biomass contained above it. The amount of heat applied to soils can vary greatly during burning events as temperatures of less than 100˚C to over 700˚C have been recorded. Here we explore a laboratory-based approach to determine the amount of C_org lost and changes in d¹³C values at different temperatures. Two soils that differ in some physical and chemical properties were selected from a location in a deciduous hardwood forest in the Appalachian Mountains of Western Maryland for analysis in the laboratory. C_org losses of 20% or greater were seen in all horizons between 200 and 400˚C with 95% organic materials being liberated at 400˚C. Past 200˚C, the levels of C_org lost for each horizon are within 12% of each other indicating a high correlation with temperature. The Dd¹³C from 200 to 400˚C are also dramatic as there is an overall enrichment of between 2.3 and 3.5‰. Further analysis indicates that amounts of organic material and clay present in the soils have no influence on the levels of C_org loss or post-burn d¹³C values in dry soil.