Join us for the School of Environmental Studies Colloquium Series Featuring Dr. Tomas Navratil
Location: BioSciences Complex, Room 1120
Atmospheric Mercury Meets the Canopy: Advances in Tree-ring Archives and Litterfall Inputs
Abstract:
Atmospheric mercury is efficiently intercepted by forest canopies, where it enters the leaf interior through stomatal uptake and is subsequently redistributed along the basipetal pathway to woody tissues. In certain tree species, this internal transport embeds atmospheric Hg signatures within tree‑rings, establishing dendrochronology as a high‑resolution biogeochemical archive for reconstructing historic atmospheric mercury concentrations. Recent advances in this field indicate that mercury even in high concentrations does not reduce the tree growth, and multi‑proxy calibration suggests high temporal precision and quantitative reliability of tree‑ring Hg records.
Tree canopies also play important role in cycling of mercury in the forest ecosystems. Litterfall mercury deposition represents the dominant flux of mercury deposition to forest soils in temperate Europe and elsewhere. Seasonal litterfall measurements across Central European sites reveal that leaf litter delivers up to 90 % of total ecosystem Hg input. The changes in litterfall mercury deposition can result from climatic (ice storms, drought), biological (infestations) and anthropogenic (changes in emissions) factors. The fate of deposited mercury is strongly affected by its high affinity to soils organic material, which stability will determine the residence time of mercury within the forest soils.
Both tree‑ring and litterfall datasets demonstrate an important effect of vegetation onto mercury cycling in the environment. The canopy acts both as a collector of atmospheric mercury and as a conduit delivering mercury to the forest floor via litter. This dual role highlights the importance of canopy processes in mediating atmospheric–terrestrial mercury exchange and underscores the value of combined dendrochronological and litterfall approaches for monitoring past and future changes in mercury deposition across European forest ecosystems.
Bio: Dr. Navratil is a Senior Researcher at the Institute of Geology of the Czech Academy of Sciences and external lecturer at the Charles University Prague. Prior to his current position he also worked for the Czech Geological Survey. He has a PhD. from the Charles University Prague and he was awarded the Fullbright stipend that he spent at the University of Maine in 2008. Tom’s research originated in the studies of acidified aquatic and forest ecosystems and later evolved into fate and biogeochemical behavior of risk elements such as mercury and lead. Majority of his research is focused on the forest ecosystems in the Central Europe and biogeochemical archives especially tree rings.