UC Merced

Black carbon in the form of biochar or charcoal has high carbon sequestration potential, i.e. it can store carbon in soils for a long time, diminishing its release to the atmosphere and helping climate change mitigation. Aerosol black carbon, in the form of soot, is the most potent short-term greenhouse-warming particle. Instant decrease in such emission would likely lead to a rapid reduction in temperatures. This doctoral dissertation encompasses a published review paper of all forms of black carbon; an original research paper describing a study of the chemical and radiocarbon properties of soot and biochar forms of black carbon materials deposited in the soil after biomass burning and fossil fuel combustion; and a study of the policy implications of their production from prescribed forest fires as follows: Paper 1 (Chapter 2): Black Carbon’s Properties and Role in the Environment: A Comprehensive Review. Paper 2 (Chapter 3): (a) Potential soil carbon implications of biochar black carbon produced from prescribed forest fires; (b) Age and source of black carbon in surface soils of Yosemite. Paper 3 (Chapter 4): Science Policy aspects of prescribed burns and their effects on carbon, black carbon and air quality impacts. This document is arranged in publication and publication-ready format, with each chapter as a paper with its own study objectives, laboratory analyses and results presented as parts of the overall goal of this research as described here. Chapter II reflects upon the current state of scientific knowledge of soot and biochar black carbon describing its physical and chemical properties, methods of extraction, and its environmental significance. A multidisciplinary review of literature from soil sciences, atmospheric sciences, combustion sciences and climate change science was employed to clarify and distinguish different black carbon types, their formation mechanisms and impacts. The subsequent chapters delve into the original research conducted for the fulfillment of the requirements of this dissertation, focusing on black carbon recently deposited and accumulated in surface soils of six sites along an elevational gradient in Yosemite National Park in Central California, which also includes the San Joaquin Valley.