The Pyrogenic Carbon Cycle

Abstract

Pyrogenic carbon (PyC; includes soot, char, black carbon, and biochar) is produced by the incomplete combustion of organic matter accompanying biomass burning and fossil fuel consumption. PyC is pervasive in the environment, distributed throughout the atmosphere as well as soils, sediments, and water in both the marine and terrestrial environment. The physicochemical characteristics of PyC are complex and highly variable, dependent on the organic precursor and the conditions of formation. A component of PyC is highly recalcitrant and persists in the environment for millennia. However, it is now clear that a significant proportion of PyC undergoes transformation, translocation, and remineralization by a range of biotic and abiotic processes on comparatively short timescales. Here we synthesize current knowledge of the production, stocks, and fluxes of PyC as well as the physical and chemical processes through which it interacts as a dynamic component of the global carbon cycle.

Surface Characterization of Aged Biochar Incubated in Different Types of Soil

“…This might have been due to the good permeability of sandy soil, leading to more C and N being leached or the good ventilation conditions speeding up the mineralization of organic carbon and nitrogen in sandy soil, thus resulting in further leaching. The C and N contents of BC were higher than R, and R higher than S and C. It has been suggested that carbon loss is dominantly driven by microbial colonization and utilization of the biochars or the mineralization of soluble organic carbon (Nguyen et al 2010;Bird et al 2015). The results were consistent with previous studies (Yao et al 2010;Hale et al 2011).…”

Source Material and Concentration of Wildfire-Produced Pyrogenic Carbon Influence Post-Fire Soil Nutrient Dynamics

“…If forests that historically experienced lower-severity fires (e.g., surface fires) undergo shifts in disturbance regimes to include high-severity fire (e.g., canopy fire) as is already the case in many forests of the western U.S. [20,21,44,45], we suggest that a greater proportion of the aboveground forest may be converted to PyC. Although it has been suggested the PyC produced during a fire may be consumed in subsequent fires [46], recent studies have found limited PyC consumption in subsequent fires [47,48]. Thus, the effects of climate change on fire regimes may lead to increased PyC stocks produced in each forest fire.…”

Pyrogenic carbon from tropical savanna burning: production and stable isotope composition

“…In order to better constrain the global PyC cycle, there is an obvious need for a deeper understanding of the factors controlling formation, translocation and mineralisation of PyC and its recalcitrant compounds, represented here by HyPyC (Bird et al, 2015;Conedera et al, 2009;Zimmermann et al, 2012). In this context, the partitioning of PyC between the proximal and distal fluxes may have a strong influence on preservation potential (Thevenon et al, 2010).…”

“…Of the total PyC produced by biomass burning, it has been estimated that > 90 % remains (initially) close to the site of production and < 10 % is emitted into the atmosphere as aerosols (Kuhlbusch et al, 1996), with much of the PyC emitted into the atmosphere being ultimately deposited in the oceans (Bird et al, 2015). PyC that remains on the ground will potentially (i) be re-combusted in subsequent fire events (Saiz et al, 2014;Santín et al, 2013) (ii) be re-mineralised by biotic/abiotic processes (Saiz et al, 2014;Santín et al, 2013;Zimmerman, 2010;Zimmermann et al, 2012), (iii) be remobilised by bioturbation, wind or water in either particulate (Major et al, 2010;Rumpel et al, 2006) or dissolved form (Dittmar, 2008;Dittmar et al, 2012) and/or (iv) accumulate in the soil organic carbon (SOC) pool (Lehmann et al, 2008).…”