Based on the results from section 3.4.2 (see also Figure ), the possible magnitude of Hg scavenging by volcanic aerosols can be constrained: The global mass flux of volcanically-derived sulfate is estimated to be ~20•10 6 Mg y - 1 , on average . Assuming that volcanic aerosols scavenge GEM proportionally to their sulfate content with a relationship of 10.4 (3.3; 24) µg GEM g sulfate -1