Elevated atmospheric CO<sub>2</sub> decreases methylmercury production in freshwater lakes.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41453862.
- Also identified by DOI 10.1038/s41467-025-67788-0 and PMC identifier 12848011.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Elevated atmospheric carbon dioxide (CO<sub>2</sub>) level reshapes microbial communities in nature, yet its consequences for neurotoxic methylmercury (MeHg) production in waters remain unclear. Here, we show that elevated CO<sub>2</sub> levels (650 and 1000 ppm) consistently reduced net MeHg production across 45 freshwater lakes spanning 1200 longitudinal kilometers, particularly in eutrophic conditions (54-96%). Elevated CO<sub>2</sub>-driven shifts in carbon substrates favored hydrogenotrophic methanogens (e.g., Methanobacterium) lacking the hgcA methylation gene over hgcA-harboring acetoclastic strains (e.g., Methanosarcina), decreasing methanogen abundance (18-98% in hgcA copies) and activity (13-53% in net CH<sub>4</sub> production) and suppressing Hg methylation. Model simulations predict a 33%-74% global decline in lake MeHg production under future CO<sub>2</sub> scenarios, partially counteract MeHg increases associated with intensified algal blooms under warming. This overlooked pathway highlights the need to integrate interacting climate drivers to improve predictions of MeHg risks in a climate-changing future.
Medical subject headings
- Methylmercury Compounds
- Carbon Dioxide
- Lakes
- Atmosphere
- Water Pollutants, Chemical