Biqing Liang's Proposal
EMSL Project ID
23992
Abstract
Black carbon (BC) can play a key role in a wide range of biogeochemical processes. Enrichment of stable forms of BC was found leading to higher soil cation exchange capacity and nutrient retention in anthropogenic soils (Anthrosols), as seen from the so-called Amazonian Dark Earth (ADE) compared to low-BC adjacent soils in Amazon regions, Brazil. Black C surface functionality is suggested the most important factor contributing to such unique and sustained fertility in Anthrosols under highly leaching and weathered tropical environments. In order to elucidate the binding mechanisms between nutrients and BC surface, we intend to use X-ray Photoelectron Spectroscopy (XPS) to study the distributions of C functional groups on BC surfaces. Soil samples will be taken from sites in Amazon region near Manaus, Brazil, which forms a chronosequence ranging from 600 years to 8700 years, and is ideal for testing the level of oxidation on BC surface over time. We will investigate the stability of BC and the formation of reactive functional groups on BC surfaces using the mass-based integrated function of XPS and expect to find more reactive C functional groups (e.g. carboxyl, hydroxyl) on BC surfaces in samples from a younger site than the older site. Additionally a depth profile will be taken at Site Lago Grande, and BC particles with a size of 63-250µm will be hand-picked, taped and measured in chamber for XPS (C 1s and O 1s) with both whole energy and detailed scans. We expect to find more reactive C functional groups (e.g. carboxyl, hydroxyl) on BC surfaces in samples from the upper profile than from the subsoil, which result from either a higher abiotic oxidation of BC itself or more adsorption of labile organic C onto surface due to external inputs. Additionally, microprobe will also be used to map the distribution of cation nutrients on BC surface. Regions of labile C with more reactive functional groups and more oxidized are expected to bear higher nutrient per unit C.
Project Details
Project type
Exploratory Research
Start Date
2007-02-13
End Date
2008-02-17
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Liang B, JC Lehmann, D Solomon, S Sohi, JE Thies, JO Skjemstad, FJ Luizao, MH Engelhard, S Wirick, and EG Neves. 2008. "Stability of Biomass-derived Black Carbon in Soils ." Geochimica et Cosmochimica Acta 72(24):6069-6078. doi:10.1016/j.gca.2008.09.028
Nguyen BT, JC Lehmann, J Kinyangi, R Smernik, and MH Engelhard. 2008. "Long-term Black Carbon Dynamics in Cultivated Soil." Biogeochemistry 89(3):295-308. doi:10.1007/s10533-008-9220-9