Unlike other metals, mercury exists
as a gas in Earth’s atmosphere. In its
elemental form, gaseous mercury
can remain in the atmosphere for months,
enabling its transport around the globe1.
However, oxidized mercury — which can
be found in both gaseous and particulate
form — is water-soluble and semi-volatile.
As such, oxidized mercury is readily
absorbed by aerosols, or removed from
the atmosphere through deposition.
Atmospheric chemistry thus controls the
spread of mercury contamination from
industrial and natural sources to distant
ecosystems (Fig. 1). Writing in Nature
Geoscience, Lyman and Jaffe2 report
simultaneous measurements of elemental
and oxidized mercury in stratosphericinfluenced
air, providing the most complete
picture yet of the chemistry of this toxic
metal in the upper atmosphere.