Forest and Prescribed Fire Impacts on Mercury Cycling and Exposure: A Global Bibliometric Analysis, Scientific Response-Lag Evaluation and Focused Review

Mercury (Hg) pollution is a global environmental issue due to its severe neurotoxic effects on humans and ecosystems. As climate change increases, both the frequency and intensity of wildfires become significant contributors to global Hg cycling. Wildfires can release long-stored Hg from forest soils via evaporation, ash movement, and post-fire erosion. These processes can even stimulate methylmercury (MeHg) production in aquatic systems, amplifying ecological and human health risks. Prescribed burning, a forest management practice, results in lower-intensity combustion, which mainly re-emits surface-layer Hg and leaves deeper mineral soil pools relatively intact. However, this process may enhance short-term Hg mobility in soils and ash. To understand how wildfire and prescribed burning-derived Hg cycling has evolved, we conducted the first comprehensive bibliometric analysis. We quantified (1) research growth and thematic evolution; (2) identified core research themes and knowledge clusters; (3) map global collaboration and institutional contributions; (4) assessed geographic research distribution relative to fire-prone regions; and finally (5) highlighted emerging frontiers and knowledge gaps. The analysis of 94 publications (1999–2025) reveals a significant increase in research on fire-driven Hg cycling. The literature is centered on themes such as MeHg, atmospheric Hg, emissions, biomass burning, redeposition, and bioaccumulation. While North America leads the field, contributions from Asia-Pacific and South America are growing through international collaborations. Furthermore, we applied response-lag evaluation to examine the direction and delay of the effect of annual changes in wildfire activity on scientific output. We found that increases in the number of wildfires globally lead to a strong increase in scientific volume with a one-year lag, and that in some countries, the response may be delayed or reversed. This finding reveals that the research community's response to environmental stress factors varies both temporally and nationally. Also, interest in prescribed fire has risen in recent years. Overall, the results suggest that the field has become increasingly interdisciplinary, integrating perspectives from climate, ecology, and management. This growing body of research highlights the need for a deeper understanding of the impacts of fire on Hg cycling, which is crucial for supporting sustainable fire management and environmental policy.