THE IDENTIFICATION OF BLACK CARBON PARTICLES WITH THE ANALYTICAL SCANNING ELECTRON-MICROSCOPE - METHODS AND INITIAL RESULTS

Combustion of fossil fuel and vegetation produces large quantities of black carbon particles (BCP) which are dispersed by winds over large a reas. Once deposited in the sediment, BCP constitute an historic recor d of anthropogenic activities and wildfires. For BCP to be significant environmental indicators, it is necessary to determine their source a s precisely as possible. A method has been developed to differentiate BCP from other carbonaceous particles, and to assign them to coal, oil , or biomass combustion using a scanning electron microscope equipped with an elemental detector (Analytical Scanning Electron Microscope, A SEM). BCP were identified in the ASEM as particles with an O/C atomic ratio of less than 0.15. Morphology (shape and surface texture) and tr ace element content (S and Cl) were used to classify BCP according to source using samples of known origin (oil, coal and wood fly-ash) and marine sediment samples from Halifax Inlet, which has undergone progre ssive urbanisation and industrialization over the last 250 years. The method is applicable to a wide size range of BCP and complete isolatio n of the BCP from the rest of the sample is not necessary. (C) 1997 El sevier Science B.V.