Last April, a symposium was held to discuss new aspects of the rapidly growing field of research focusing on black carbon in soil, sediment, and the atmosphere. About 70 scientists attended the 2-day session during the European Geosciences Union General Assembly, in Vienna. Part of this symposium included a workshop on chemical reference materials, where results of an interdisciplinary intercomparison of black carbon (BC) measurements in different environmental matrices were released.

BC is the product of incomplete combustion of fossil fuels and biomass and is also called elemental carbon in the atmospheric sciences. BC moves between the atmosphere, oceans, and soils, in the process affecting human health, the Earth's radiative budget, ocean carbon cycling, and soil carbon storage. However, a lack of standards common to atmospheric scientists, oceanographers, soil scientists, and ecologists has made it challenging to assess the role of BC in the carbon cycle. In particular, quantification of BC in complex matrices has proven to be problematic, as was made clear in a recent intercomparative study of BC in soils, where BC concentrations measured by a range of techniques differed by 2 orders of magnitude. BC exists as a chemical continuum of combustion products, and some methods may be ideal for detecting only a fraction of the total BC pool (e.g., soot). Other methods may detect non-BC materials in some types of samples, and some may fail to detect BC in other sample types.