Black Carbon in the Earth System: Occurrence, Stability, and Measurement.

Black carbon (BC) is thought to be one of the most stable forms organic matter can take in soils and marine sediments.  Two avenues have been used to track its long-term stability in the environment:  natural radiocarbon measurements of BC in soils and sediments, and measurements of increasing BC/total organic carbon ratios in soils and sediments exposed to increasing levels of oxidants.   Both of these approaches have documented that BC has a long, but finite environmental residence time.  Many potential mechanisms have been proposed to decompose BC in the environment, and understanding these decomposition processes is key to effective predictions of BC residence times. 
It is likely that stability and decomposition of BC varies with environment (e.g. terrestrial or marine; oxic or anoxic) and timescale.  In this presentation, I will discuss the occurrence, stability, and measurement of black carbon across a range of ecological conditions and geologic timescales.