Coupled and decoupled carbon-mercury dynamics across forest ecosystem continua.
basic_science · Level V
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- Record sourced from PubMed, PMID 42660955.
- Also identified by DOI 10.1038/s41467-026-76140-z.
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Abstract
Carbon sustains life, whereas mercury is a global toxin, yet their cycling in forests appears to be intimately linked. Here we show, using elemental stoichiometry, carbon and mercury isotopes and a global forest synthesis, that forests simultaneously couple and decouple mercury from carbon along contrasting ecosystem continua. Mercury/carbon ratios remain tightly conserved (0.5-0.9 × 10<sup>-6</sup>) along the aqueous-phase continuum, indicating proportional mercury transport with dissolved organic carbon. In comparison, mercury/carbon ratios increase by nearly three orders of magnitude from the atmosphere to soils (0.007-3.6 × 10<sup>-6</sup>) along the solid-phase continuum, reflecting progressive mercury enrichment during litter and soil organic matter decomposition. Standing litter acts concurrently as a net carbon source and mercury sink, whereas biomass regulates coupled carbon and mercury storage and litterfall deposition. These contrasting carbon-mercury trajectories reveal how forests both retain and redistribute atmospheric mercury and provide a conceptual framework for understanding terrestrial mercury cycling under environmental change.