Mercury as a global pollutant is regularly mentioned in the news with respect to discussions about its emissions. Due to the low reactivity of gaseous elemental mercury in the atmosphere the wet deposition is low at 2–3 µg/m2/year. In forest environment, the main deposition path of Hg to the forest floor is litterfall. Litterfall Hg deposition, including deposition of biomass, such as needles, twigs, cones and bark, reaches usually 20–50 µg/m2/year. Long-term research of two mountain lake catchments in the Šumava (Bohemian Forest) National Park area indicated a significant decrease in Hg deposition in litterfall since the beginning of the 21st century. Furthermore, this research shows that the bark beetle infestation may increase Hg deposition up to 5 fold due to high biomass deposition. This study evaluated individual contribution of spruce litterfall components, such as needles, twigs, cones, bark, lichen and unidentifiable debris separately. Research published in Science of the Total Environment (IF 4,6) Journal was performed within a broad cooperation with the Biology Centre of the Czech Academy of Sciences, U.S. Geological Survey and Global Change Research Centre of the Czech Academy of Sciences.