摘要
以位于青藏高原东缘的贡嘎山海螺沟冰川退缩区为研究对象,基于有机土壤中汞、碳、氮的含量变化及化学计量关系,探讨了植被格局变化对土壤汞积累分布的影响.结果表明,有机土壤形成前期(10年尺度内),不同林分均因凋落物快速降解导致碳、氮含量显著降低与汞的络合位点增加,致使土壤中汞呈现强烈的富集效应;有机质后续的慢速降解矿化过程(10年至百年尺度)中,植被类型的影响作用明显,不同林分下有机土壤中汞的积累模式存在显著差异.针叶林有机层土壤汞浓度(277.54±117.19)ng/g大于演替前期阔叶林(204.23±14.38)ng/g的值.在有机质慢速矿化阶段中,阔叶林土壤汞随深度递减,而针叶林土壤汞基本保持恒定,这与针叶凋落物中氮含量(2.11%±0.20%)较阔叶(2.64%±0.10%)低,使得其针叶凋落物降解矿化速率变慢有关.此外,阔叶林分有机土壤中Hg/C随C/N增加而显著降低,但由于针叶林不同的凋落物输入特征和汞积累模式,其Hg/C与C/N不再呈现显著负相关.
To assess impacts of vegetation on the distribution and accumulation of mercury(Hg)in forest soils,we comprehensively determined the contents and stoichiometric relationships among Hg,carbon(C)and nitrogen(N)in forest soils of Hailuogou glacial retreated regions of the Gongga Mountain,Eastern Qinghai-Tibet Plateau.Results demonstrated the enhanced Hg accumulation in all decomposing litter due to the rapid loss of N and C mass during the initial stage of organic soil formation(at ten-year scale).However,the different Hg accumulation process existed between the pioneer broadleaf tree forest and the climax coniferous tree forests in the period of slow degradation processes of organic matter(at decadal to centennial scales).More in detail,the soil mercury concentration in the organic layer of coniferous forest(277.54±117.19ng/g)was significantly greater than that of deciduous forest(204.23±14.38ng/g);we observed the decreasing mercury concentration with the increasing organic soil depth in deciduous forests,while the nearly constant concentration in coniferous forests.These can be explained by the lower N content in coniferous forests than in broadleaf forests(2.11%±0.20%versus 2.64%±0.10%)which leading to the slow the coniferous litter degradation rate.In addition,Hg/C ratio distinctly decreased with the increasing C/N ratio in deciduous organic soils,but without profile trends in coniferous forest soils because of their largely different litter input characteristics and the Hg accumulation patterns.
作者
杨路寒
王训
王定勇
YANG Lu-han;WANG Xun;WANG Ding-yong(College of Resources and Environment,Southwest University,Chongqing 400715,China;State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;Interdisciplinary Research Center for Agriculture Green Development in Yangtze River Basin,Southwest University,Chongqing 400715,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2023年第6期2993-3001,共9页
China Environmental Science
基金
国家自然基金面上项目(41977272)。
关键词
冰川退缩区
植被类型
碳氮
化学计量比
汞积累过程
glacier retreated area
vegetation
carbon and nitrogen
stoichiometric ratio
mercury accumulation
