Over the past several months, the Permafrost–Mercury (PermHg) Action Group has made substantial progress toward completing a harmonized, open-access database of mercury (Hg) observations from permafrost-affected regions. We compiled 117,802 individual measurements from 59 published studies spanning soils, vegetation, and water bodies across the northern hemisphere permafrost domain. This database fills a critical data gap in quantifying terrestrial Hg storage and assessing the potential mobilization of legacy Hg with ongoing permafrost thaw.
During the past year, our efforts focused on harmonizing and quality-controlling the data through standardized units, observation-type classification, and metadata consistency checks. These steps enabled robust statistical analyses, revealing that Hg concentrations consistently follow the pattern: lake sediment > soil > vegetation > water. Median concentrations were 70 ng g⁻¹ for lake sediment, 50 ng g⁻¹ for soil, 15 ng g⁻¹ for vegetation, and 2 ng L⁻¹ for water.
Figure 1 illustrates the number of Hg observations collected over time, showing steady growth in measurements since the 1990s and underscoring the increasing scientific attention to Hg cycling in permafrost regions.
We have now completed a final draft of our manuscript, A Consolidated Database of Mercury Observations for Permafrost Regions, which will soon be submitted to Earth System Science Data (ESSD). The database is finalized and will become publicly available through GitHub and Zenodo once the manuscript is accepted. Several members of the Action Group will continue to maintain and monitor contributions via GitHub to ensure the database remains a living resource for the research community.
Provided by Christine Olson
Figure 1. 2 D column chart showing the number of observations collected over time for (a) lake sediment, (b) vegetation, (c) soil, and (d) water Hg observations in the PermHg database.