Analysis of black carbon in sediments and soils using multi-element scanning thermal analysis (MESTA)

Analysis of black carbon (BC) is still a critical issue in carbon cycle research due to the lack of standardized methodology. This study was initiated to investigate the feasibility of quantifying BC in solid samples using a multi-element scanning thermal analysis (MESTA) method. The method determines the C and N contents of a sample, with respect to their thermal stability, over the entire organic carbon (OC)/BC continuum. There is a good separation of BC and non-BC materials in the MESTA thermograms. The tentative BC criterion is the carbonaceous material with peak carbon decomposition temperature 550 °C. Charring seemed not to be a problem in the determination of BC using MESTA because the char products were not thermally stable enough to be classified as BC. Comparison of the MESTA method with the International BC Ring Trial methods (http://www.geo.unizh.ch/phys/bc/) shows that the BC content of a Chernozem, Vertisol and the SRM 1649a urban dust are in the mid-range, while those of wood char and grass char are at the lower end of the ring trial methods. The study also reveals a significant amount of N structurally associated with the thermally stable carbonaceous material.