Perspectives

The atmospheric chemistry of mercury, a global priority pollutant, is key to its transport and deposition to the surface environment. Assessments of its risks to humans and ecosystems rely on an accurate understanding of global mercury cycling.

) lead to a significant model underestimation of global observations of these oxidized species in the troposphere and their surface wet deposition. This implies that there must be currently unidentified mercury oxidation processes in the troposphere.^II and Hg^IThis work shows that the set of chemical reactions and rates currently employed to interpret the delicate balance between Hg oxidation and reduction in the atmosphere fails to explain the observed atmospheric mercury concentrations and deposition. We report that model simulations incorporating recent theoretical developments in the photoreduction mechanisms of…

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(Photograph by Andrea Baccarini)

New atmospheric particle formation is one is the largest uncertainties in climate simulations. Although it is known for the last two decades that iodine oxides form new particles in the lower atmosphere, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism.

In a recent study (Nature Communications, 2020: https://www.nature.com/articles/s41467-020-18252-8), combined laboratory experiments, theory and modelling revealed the mechanism that connects oceanic iodine emissions and atmospheric particle formation. In a recent study published in Nature Communications (https://doi.org/10.1038/s41467-020-18551-0), it has been reported that iodine is the main source of new particles in the central Arctic. The observations were made during…

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