Abstract: It is of great significance for understanding the mercury (Hg) biogeochemical cycle to reveal the distribution characteristics and methylation mechanism of Hg in alpine ecosystems. In this study, we analyzed the distribution characteristics of Hg and methylmercury (MeHg) in the surface soil and litter of four vegetation zones on the northern slopes of the Changbai Mountain, and elucidated the role of environmental factors on Hg methylation. The results showed that the mean concentration of total Hg in soil was 72.9±32.3 ng·g^-1. The mean concentration of MeHg was 4.5±1.7 ng·g^-1, accounting for 7.79% of total soil Hg. The mean concentration of total Hg in litter was 155.5±34.4 ng·g^-1. SUVA₂₅₄, SUVA₂₆₀ and Mn in soil had negative effects on MeHg, while total carbon concentration had a positive effect on MeHg. There were obvious altitudinal distribution patterns of Hg and MeHg in soils of Changbai Mountain, with total Hg concentrations in different vegetation zones showing the order of alpine tundra zone > Betula ermanii forest zone > coniferous forest zone > coniferous and broadleaf forest zone, and MeHg concentrations showing the order of Betula ermanii forest zone > alpine tundra zone > coniferous forest zone > coniferous and broadleaf forest zone. MeHg concentration in soil was mainly influenced by altitude, SUVA₂₅₄, Mn and total Hg concentration, and was not related to total Hg concentration in litter.

Key words: Changbai Mountain, mercury, methylmercury, biogeochemical cycle