Elemental tracers of distant regional pollution aerosols.

A seven-element tracer system shows that regional pollution aerosols of both North America and Europe have characteristic signatures that can be followed into remote areas up to several thousand kilometers downwind. In aerosols of mixed origin, regional contributions to the tracer elements can be resolved by least-squares procedures. After transport of several hundred kilometers, secondary sulfate can also be apportioned satisfactorily. Regional elemental tracers thus offer a way to determine the sources of pollution aerosol in important areas such as the northeastern United States, Scandinavia, and the Arctic.