Black carbon (BC) represents a wide-range of highly aromatic carbonaceous material generated from the incomplete combustion of biomass and fossil fuels. High yearly production yields (50 to 270 Tg/year), ubiquity in soils, marine sediments, and aerosols, potential as a beneficial soil additive, and important role in global carbon budgets necessitates a detailed knowledge of BC reactivity in the environment. This reactivity is a function of many of its own structural and chemical properties including those inherited through progressive surficial oxidation. The development of oxidation rinds and progressive sloughing or dissolution may also be an important controlling factor in the production of highly aromatic condensed carbon fractions and their subsequent utilization by soil microbial population. In this abstract we present analysis of progressively photo-oxidized black carbon residues and dissolved fractions by a variety of spectroscopic tools including Fourier transform infrared spectroscopy and molecular tools including TMAH thermochemolysis.  Results demonstrate a chemical distinction between extracted residues and dissolved fractions as dissolved fractions showed lower aromatic content and higher carboxylic functionality. The chemically distinct soluble fractions may lead to specific microbial palatability but also to chemical affinities to soils and minerals different than what might be predicted from the average chemical composition from the BC residues.

Surficial oxidation of black carbon in the environment and its chemical implications

246th National Meeting (2013)

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