High tree-ring mercury reveals a century of extreme emissions and contamination in a Central European pollution hotspot

Tomáš Navrátil; Tereza Nováková; Katrien Boonen; Jan Rohovec; Michal Roll; Jozef Hančuľák; Jiří Lehejček

doi:10.1016/j.envpol.2025.127531

High tree-ring mercury reveals a century of extreme emissions and contamination in a Central European pollution hotspot

Environ Pollut. 2026 Feb 1:390:127531. doi: 10.1016/j.envpol.2025.127531. Epub 2025 Dec 13.

Authors

Tomáš Navrátil¹, Tereza Nováková², Katrien Boonen³, Jan Rohovec², Michal Roll², Jozef Hančuľák⁴, Jiří Lehejček³

Affiliations

¹ Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, Prague 6, 165 00, Czech Republic. Electronic address: navratilt@gli.cas.cz.
² Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, Prague 6, 165 00, Czech Republic.
³ Faculty of Environment, Jan Evangelista Purkyně University, Pasteurova 3632/15, 400 96, Ústí nad Labem, Czech Republic.
⁴ Institute of Geotechnics of Slovak Academy of Sciences, Watsonova 45, 04001, Košice, Slovakia.

PMID: 41397496
DOI: 10.1016/j.envpol.2025.127531

Abstract

Understanding the historical extent of anthropogenic mercury (Hg) emissions is essential due to Hg's persistence and toxicity, yet long-term atmospheric records are scarce. Tree rings offer a valuable high-resolution archive of historical atmospheric Hg. Here, we used Larix decidua tree rings to reconstruct a century of atmospheric Hg pollution in the Rudňany valley, a heavily contaminated mining area of Hg-rich Fe ores in Central Europe with limited historical air Hg measurements. Tree-ring Hg concentrations allowed reconstructing air Hg concentrations, reflecting changes in smelting technologies, locations and total Hg production. Among the five sites studied, the highest Hg concentrations were found at ZAV (valley entrance) and PAT (near a mining waste heap), with a maximum of 3084 μg kg^-1 in a single tree-ring segment at PAT for a 1943-1947 segment, among the highest tree-ring Hg concentrations ever reported. Notably, peak Hg emissions occurred prior to 1960, decades before production peaked, reflecting inefficiencies in smelting technologies. A linear model was used to estimate historical air Hg concentrations from tree-ring data, with outputs consistent with the few available historical measurements. However, site-specific variation in the tree-ring Hg to air Hg ratio suggests that environmental and physiological factors influence Hg concentrations. To assess potential confounding effects, we analyzed tree growth and age-related influences on Hg accumulation. Tree age had only a minor impact on Hg trends. Growth suppression was observed at the highly polluted site ZAV, while tree-ring width at the less contaminated JOZ appeared unaffected by pollution. These findings confirm Larix decidua as a robust archive for Hg reconstruction, capable of recording pollution histories even under extreme contamination and across trees of varying ages.

Keywords: Atmospheric Hg; European larch; Fe-ore processing; Larix decidua; Legacy pollution; Rudňany ore deposit; Slovakia.

MeSH terms

Air Pollutants* / analysis
Air Pollution / statistics & numerical data
Environmental Monitoring*
Environmental Pollution / statistics & numerical data
Europe
Larix / chemistry
Mercury* / analysis
Mining
Trees / chemistry

Substances

Mercury
Air Pollutants