Oxidation of Black Carbon by Biotic and Abiotic Processes

Journal Article · Wed Nov 01 04:00:00 EST 2006 · Organic Geochemistry, 37(11):1477-1488

DOI:https://doi.org/10.1016/j.orggeochem.2006.06.022· OSTI ID:898099

Cheng, Chih-hsin; Lehmann, Johannes C; Thies, Janice E; Burton, Sarah D; Engelhard, Mark H

The objectives of this study were to quantify the relative importance of either biotic or abiotic oxidation of biomass-derived black carbon (BC) and to characterize the surface properties and charge characteristics of oxidized particulate BC. We incubated BC and BC-soil mixtures at two different temperatures (30 C and 70 C) with and without microbial inoculation, nutrient additions, or manure amendments for four months. Abiotic processes were more important for oxidation of BC than biotic processes during this short-term incubation, as inoculation with microorganisms did not change any of the measured parameters. Black C incubated at both 30 C and 70 C without microbial activity showed dramatic decreases in pH (in water) from 5.4 to 5.2 and 3.4, as well as increases in cation exchange capacity (CEC at pH 7) by 53% and 538% and in oxygen (O) contents by 4% and 38%, respectively. Boehm titration and Fourier transform infrared (FTIR) spectroscopy suggested that the formation of carboxylic functional groups was the reason for the enhanced CEC during oxidation. The analyses of BC surface properties by X-ray photoelectron spectroscopy (XPS) indicated that the oxidation of BC particles initiated on the surface. Incubation at 30 C only enhanced oxidation on particle surfaces, while oxidation during incubation at 70 C penetrated into the interior of particles. Such short-term oxidation of BC has great significance for the stability of BC in soils as well as for its effects on soil fertility and biogeochemistry.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 898099
• Report Number(s): PNNL-SA-48811; 13303; 18899; KP1303000
• Journal Information: Organic Geochemistry, 37(11):1477-1488, Journal Name: Organic Geochemistry, 37(11):1477-1488
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
58 GEOSCIENCES
BIOGEOCHEMISTRY
CARBON
CARBON BLACK
Environmental Molecular Sciences Laboratory
ION EXCHANGE
MICROORGANISMS
OXIDATION
PARTICULATES
SPECTROSCOPY
SURFACE PROPERTIES
X-RAY PHOTOELECTRON SPECTROSCOPY