Abstract: To clarify the seasonal and regional distribution of mercury (Hg) concentration in leaf litter of typical vegetations, we collected leaf litter of the main dominant tree species for Hg concentration analysis in representative areas with serious Hg pollution, including Guizhou, Jilin, Shaanxi, Hubei, Liaoning, and Chongqing, as well as at least two provinces in each of the seven geographic regions in China during August 2020 to October 2021. The results showed that: (1) Among the different vegetation types, Hg concentration in leaf litter of evergreen broad-leaved forests (75.88±22.28 ng·g^-1, ranging from 41.68 to 181.58 ng·g^-1) was 1.97 times as high as that of deciduous broad-leaved forests (38.58±30.65 ng·g^-1, ranging from 2.11 to 123.86 ng·g^-1). (2) In terms of seasonal pattern, leaf litter Hg concentration of most tree species increased gradually with the growing season. (3) On the spatial scale, leaf litter Hg concentration showed a trend of east China > central China > southwest China > south China > northwest China > northeast China > north China. Leaf litter Hg concentration in east China being 77.57±29.65 ng·g^-1 (ranging 38.04-109.01 ng·g^-1), which was 3.01 times higher than that in northeast China (25.73±8.28 ng·g^-1, ranging 11.95-37.01 ng·g^-1). In northeast China, central China and northwest China, leaf litter Hg concentration was higher in the heavily Hg-polluted sites than in the non-heavily polluted sites. Our results can be applied for the selection of afforestation species in Hg-polluted sites, and provide data support for assessing Hg absorption capacity of forest ecosystems.

Key words: vegetation type, litterfall amount, mercury concentration in leaf litter, geographic distribution