Background
The term black carbon (BC) is a general one applied to various carbonaceous products of incomplete combustion and includes chars, charcoals and soots. BC is ubiquitous in the environment, including in aerosols, sediments and soils. Current intercomparison efforts have made clear the need for a suite of widely available and representative BC benchmark materials. To address this need, an international steering committee was formed during the 1999 Geochemical Society meeting (Goldschmidt Conference). The members of the committee (1999-2008) were
- Michael W. I. Schmidt, Co-chair (Physical Geography, University of Zurich, Switzerland)
- Carrie Masiello, Co-chair (Department of Earth Science, Rice University, USA)
- William P. Ball, (Whiting School of Engineering, Johns Hopkins University, USA)
- Lloyd A. Currie (retired), (NIST, USA)
- Evelyn Krull, (CSIRO Adelaide, Australia)
- Dwight M. Smith, (Department of Chemistry and Biochemistry, University of Denver, USA).
This committee was charged with developing representative and accessible BC reference materials for the environmental sciences community. In May 2000 this committee issued preliminary recommendations for BC materials spanning the combustion continuum (Reference Materials).
Recommendations include
i) five BC-containing environmental matrices for which BC quantification is often sought, namely aerosol, two soils, marine sediment and dissolved organic matter
ii) three laboratory-produced BC-rich materials, namely soot, wood charcoal and grass charcoal, and
iii) four potentially interfering materials, creating BC during analysis (melanoidin, shale, two coals).
This collection had to be chosen to balance a number of competing demands. Materials must be:
- generally available
- homogeneous
- stable over a longer period of time
- inexpensive to obtain
- represent natural samples
After issuing preliminary recommendations, the BC steering committee actively solicited input from scientists and used this information to make a final set of recommendations of BC benchmark materials that were analyzed in a comparative study. A summary of these recommendations was published in EOS (PDF, 56 Kb), the weekly journal published by the American Geophysical Union.
The comparative study was published in Global Biogeochemical Cycles (Comparison of black carbon quantification methods using reference materials from soil, water, sediment, and the atmosphere, and implications for the global carbon cycle. Global Biogeochemical Cycles, 21, GB3016, doi:10.1029/2006GB002914).
A short report on the symposium held on black carbon research in soil, sediment and the atmosphere at the 2007 European Geoscience Union meeting in Vienna (18-19 April 2007), as well as summary of the comparative study conclusions, can be found here (PDF, 61 Kb).