DATE: Friday, November 02, 2018 TIME: 2:30 pm (refreshments at 2:15 pm) PLACE: ENR building, room 223 14 College Farm Road, New Brunswick, NJ
Alain Plante
Earth & Environmental Science, University of Pennsylvania
Thermal analysis and the bioenergetics of soil carbon
The amount of carbon stored in soil and its exchange with the atmosphere is of great interest because of the key roles these processes play in global carbon cycling, climate change and sustainable agriculture. Soil carbon can be found in several forms: organic carbon as soil organic matter, inorganic carbon as carbonate minerals, pyrogenic carbon as char derived from fire, and geogenic carbon as coal. Soil carbon stability refers to its resistance to decomposition (i.e., the opposite of decomposability) and refers to how long carbon can be expected to stay in soil before being returned to the atmosphere. Soil carbon stability can be investigated using a wide range of biological, chemical and physical methods. This presentation will illustrate a few cases studies of how we have been using thermal analysis techniques as a novel way to examine soil carbon form and stability. The combustion reactions that occur at various temperatures during slow heating are indicative of the form and chemical composition of the carbon present in the sample, as well as the degree to which the carbon is associated with the minerals. Thermal analysis makes it possible to determine the energy stored in soil organic matter that may be available to microorganisms during decomposition; and the energy required for combustion, which can be seen as an energetic barrier to decomposition. Because organic, inorganic, pyrogenic and geogenic forms of carbon burn at different temperatures in soils and sediments, thermal analysis is also an effective method for distinguishing and quantifying them.