Point measurements of chemical tracers transported via the atmosphere contain information regarding origins, atmospheric mixing, scavenging, and in situ chemical processes. A new technique for accessing this information is presented. The method is based on the physical constraints that are naturally imposed on the data. In order to evaluate the performance of this new technique, we have applied it to artificially generated data sets. Furthermore, the method is used to analyze eight chemical time series obtained from ice core data. Three distinct source vectors dominate the composition throughout the last 41 kyr period. By comparing ratios among the eight chemical species within each source vector, it is possible to show that they describe three source types: oceanic, continental, and biochemical land sources. ¿ 1998 American Geophysical Union