Mercury emissions from active volcanoes are of interest for estimating the
volcanogenic contribution of mercury to the atmosphere. Mercury samples wer
e collected from sulfur fumaroles in the large exhaling fields. Mercury con
centrations in the fumarolic gases of twelve geothermal activity areas vari
ed between 1.8 and 781 mu g/m(3) with a geometrical mean 39.7 mu g/m(3). Wi
th these analyses, yearly mercury output from geothermal fumarolic sources
in Japan was estimated as 1.4 tons. The contribution to the environment of
mercury released from geothermal areas in Japan was estimated as about 2%.
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