Searching for manganese pollution from MMT anti-knock gasoline additives in snow from central Greenland

Mn has been measured in snow core samples dated from 1967 to 1989 collected in central Greenland. Observed concentrations range from 16 to 236 pg g −1. A large fraction of Mn in Greenland snow is found to originate from rock and soil dust. The different possible natural sources for `excess' Mn above that contributed from rock and soil dust include volcanoes, natural vegetation fires and continental biogenic emissions. They could explain part of the observed excess. At least part of it is, however, probably related to anthropogenic inputs, especially from North America. Aside from industrial sources, MMT (methyl-cyclopentadienyl manganese tricarbonyl) anti-knock gasoline additives are good candidates, but our data do not allow to clearly identify their influence. Unambiguous identification will require the direct determination of organo-Mn compounds in comprehensive series of Greenland snow samples with sub-seasonal resolution using highly sensitive speciation techniques.