Long-term mercury variations in tree rings of the permafrost forest,northeastern China  

作　　者：Huhu KANG Xiaohong LIU Junming GUO Qiuliang ZHANG Yabo WANG Jie HUANG Guobao XU Guoju WU Wensen GE Shichang KANG 

机构地区：[1]State Key Laboratory of Cryospheric Science,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China [2]School of Geography and Tourism,Shaanxi Normal University,Xi'an 710119,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Forest College,Inner Mongolia Agricultural University,Hohhot 010018,China [5]Key Laboratory of Tibetan Environment Changes and Land Surface Processes,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [6]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Chinese Academy of Sciences,Beijing 100101,China

出　　处：《Science China Earth Sciences》2022年第7期1328-1338,共11页中国科学（地球科学英文版）

基　　金：supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA20040501);the National Natural Science Foundation of China(Grant Nos.41971104 and 41571196);the Fundamental Research Funds for the Central Universities(Grant No.GK202107009);the State Key Laboratory of Cryospheric Science(Grant No.SKLCS2020-09);Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences。

摘　　要：Permafrost is a potential mercury(Hg)pool released by thawing,which can raise the risk of Hg pollution under global warming.Tree rings are useful archives of environment-specific Hg exposure over long periods.We determined Hg concentrations in tree rings of two dominant tree species(Larix gmelinii Rupr.and Pinus sylvestris var.mongolica)at permafrost sites in northeastern China.The biweighted mean Hg concentrations ranged from 0.36 to 3.96 ng g^(-1) from 1840 to 2014.The tree-ring width had no significant influence on the Hg concentration.Larch Hg increased slightly before the 1970 s and peaked in the 1990 s.However,the pine Hg concentration increased continuously until the 1930 s,decreased rapidly until the 1970 s,then rose to a peak in the late 1980 s.The change of Hg concentrations in larch and pine revealed a time offset of 4 to 5 years,which implied possibly high mobility of Hg in pine tree rings.Higher Hg concentrations from 1920 to 1960 and subsequent decreases in isolated permafrost forests revealed the local geographical Hg cycling history.Lower Hg concentrations and faster increases in larch suggest the role of additional winter Hg loading for the evergreen pine and species-specific differences in root absorption in response to melting permafrost.Our results highlight possible geographical impacts on tree-ring Hg records,improve understanding of Hg cycles in permafrost forest,and suggest a need to sample additional species in a range of permafrost environments.

关 键 词：Tree rings MERCURY Long-term variations LARCH PINE Geographic environment Permafrost forest 

分 类 号：X173[环境科学与工程—环境科学]