Estimating atmospheric mercury concentrations with lichens.

Area of Science:

• Environmental Science
• Biogeochemistry
• Ecotoxicology

Background:

• Elemental gaseous mercury (Hg(0)) is a significant atmospheric pollutant.
• Epiphytic lichens are sensitive bioindicators of air quality.
• Understanding Hg(0) uptake in lichens is crucial for environmental monitoring.

Purpose of the Study:

• To investigate the uptake kinetics of Hg(0) in three epiphytic lichen species.
• To evaluate the efficiency of lichens for Hg(0) accumulation.
• To assess the potential of lichens for estimating atmospheric Hg concentrations.

Main Methods:

• Exposure of Pseudevernia furfuracea, Evernia prunastri, and Xanthoria parietina to varying Hg(0) concentrations (10-45 μg/m³) and temperatures (10-30 °C).
• Analysis of Hg accumulation over time and assessment of Hg release after exposure (clearance).
• Application of first-order kinetics equations to model Hg uptake.

Main Results:

• All tested lichens accumulated Hg(0) with exposure time; no significant Hg release was observed after clearance.
• Pseudevernia furfuracea exhibited the highest Hg accumulation, while Evernia prunastri showed the lowest.
• Xanthoria parietina demonstrated intermediate Hg accumulation, with uptake kinetics independent of temperature (10-30 °C).

Conclusions:

• Lichens effectively accumulate atmospheric Hg(0).
• Xanthoria parietina's temperature-independent Hg uptake allows for reliable estimation of ambient Hg concentrations.
• Epiphytic lichens serve as valuable tools for atmospheric mercury monitoring.