长白山不同植被带土壤汞垂直分布及甲基化驱动因素

Vertical distribution of soil mercury and its methylation drivers in different vegetation zones of Changbai Mountain

揭示高山生态系统中汞分布特征及甲基化机制,对于认识汞生物地球化学循环具有重要意义。本研究以长白山北坡4个植被带表层土壤及枯落物为对象,分析其中汞与甲基汞分布特征,阐明环境因子对汞甲基化的作用。结果表明:长白山土壤总汞均值为72.9±32.3 ng·g^(-1),甲基汞均值为4.5±1.7 ng·g^(-1),甲基汞平均占比为7.79%,枯落物中总汞均值为155.5±34.4 ng·g^(-1);土壤中的汞和甲基汞浓度均随海拔升高而呈现上升趋势,土壤中甲基汞浓度与总汞浓度呈显著正相关,土壤SUVA_(254)、SUVA_(260)和Mn对甲基汞具有负效应,土壤总碳浓度对甲基汞具有正效应;长白山土壤中汞和甲基汞存在明显的垂直性分布特征。不同植被带中总汞浓度表现为高山苔原带>岳桦林带>针叶林带>针阔混交林,甲基汞浓度表现为岳桦林带>高山苔原带>针叶林带>针阔混交林;土壤中甲基汞主要受海拔、SUVA254、Mn以及总汞的影响,与枯落物总汞浓度关系不大。

It is of great significance for understanding the mercury(Hg)biogeochemical cycle to reveal the distri-bution characteristics and methylation mechanism of Hg in alpine ecosystems.In this study,we analyzed the distri-bution 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).SUVA_(254),SUVA_(260) and Mn in soil had negative effects on MeHg,while total carbon concen-tration 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 con-centrations showing the order of Betula ermanii forest zone>alpine tundra zone>coniferous forest zone>conifer-ous 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.