High mercury accumulation in two subtropical evergreen forests in South China and potential determinants.
Forests play an important role in global mercury (Hg) cycling. To explain the high Hg accumulation in subtropical forest ecosystems, we studied temporal dynamics of Hg, carbon (C), nitrogen (N), and sulfur (S) in forest soil profiles, as well as litterfall flux and precipitation, in an old-growth moist evergreen broadleaf (EB) forest and a mossy coppice (MC) forest from South China over seven years. The mean soil Hg concentration was 257 ± 14 ng g-1in the O-horizon and 248 ± 15 ng g-1in the A-horizon for the EB forest, and 94 ± 27 ng g-1in the O-horizon and 70 ± 11 ng g-1in the A-horizon for the MC forest. Annual variations in Hg concentration were suggested to be associated with variations in precipitation and litterfall biomass. Significant vertical Hg transport was only observed in the MC forest, which was attributed to its lower organic matter content. Correlation and stoichiometry analyses further suggested that the dynamics in Hg concentration in the forest floor was also closely linked to the variation in S concentration. Additionally, the difference in the soil Hg pool between these two forests was attributed to different litterfall biomass fluxes.
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Xishuangbanna, Yunnan 666303, China.
Zhiyun
Z
Lu
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China; University of Chinese Academy of Sciences, Beijing, 100049, China. Electronic address: wangxun@mail.gyig.ac.cn.
Xun
X
Wang
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Xishuangbanna, Yunnan 666303, China.
Yiping
Y
Zhang
Department of Organismic and Evolutionary Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA.
Yong-Jiang
YJ
Zhang
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Xishuangbanna, Yunnan 666303, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Kang
K
Luo
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Xishuangbanna, Yunnan 666303, China.
Liqing
L
Sha
D018533:Biomass; D044002:Bryophyta; D002244:Carbon / Q000032:analysis; D002681:China; D002980:Climate; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D065928:Forests; D006863:Hydrogen-Ion Concentration; D008628:Mercury / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D011891:Rain; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D013455:Sulfur / Q000032:analysis
D012987:Soil; D012989:Soil Pollutants; D013455:Sulfur; D002244:Carbon; D008628:Mercury; D009584:Nitrogen
Litterfall biomass; Soil Hg; Subtropical evergreen forest