Influence of climate warming on peatland net mercury gas fluxes: Results from the SPRUCE experiment.

This study investigates the cumulative impact of simulated warming on peatland net mercury (Hg) gas fluxes at the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment in northern Minnesota. Within the global Hg cycle, exchanges between landscape pools and the atmosphere play a critical role in both the deposition and long-range transport of Hg, making atmospheric processes a key driver of global Hg mobility. Utilizing passive air samplers (PAS), we measured mean Hg concentrations in large, open-top enclosures across a gradient of air and soil temperatures and carbon dioxide (CO2) treatments. The results confirmed a significant positive correlation between temperature and net Hg gas flux, however there was no correlation with CO2 variation. This is among the first studies to continuously quantify net mercury gas fluxes under experimentally elevated, whole-ecosystem temperatures in situ, addressing a key gap in understanding how climate warming influences the global mercury cycle. The findings underscore the sensitivity of peatland Hg emissions to temperature variations, suggesting that warming could increase atmospheric Hg levels, posing environmental and public health risks. This study highlights the necessity for further research into climate-Hg cycle feedbacks in the context of global warming and their implications for human health and environmental policy.