|Alternative Title||The vertical differentiation of mecury concentrations and storages in some typical ecosystems along the altitudinal belt in eastern slope of the Gongga Mountain|
|Place of Conferral||北京|
|Keyword||汞 含量 贮量 垂直带 贡嘎山|
工业革命以来，人类活动对生物圈的影响已从区域扩展到全球，重金属污染已成为当今全球性的环境问题。在这些重金属中，Hg作为“五毒元素”之首，对人类健康和生态系统安全的威胁尤为突出。贡嘎山位于青藏高原的东部，其东坡垂直带谱植被生态系统对于监测区域乃至全国尺度环境的变化具有重要意义。本研究在贡嘎山东坡垂直带谱中选取四个典型生态系统作为研究对象，详细测定并分析了生态系统优势种植物与土壤各层次的Hg含量；并结合植物生物量以及土壤重量数据，计算出不同海拔生态系统Hg贮量及其在各组分的分配；比较分析了同一生态系统Hg含量和贮量的差异以及不同典型生态系统Hg含量和贮量的不同；初步探究了不同生态系统中Hg分布的主要影响因素，为全面揭示高山地区生态系统Hg的生物地球化学行为提供科学参考。论文主要研究结果如下： 1、垂直带不同海拔典型生态系统活植物体Hg含量特征不同海拔典型生态系统乔灌层优势种枝、叶中Hg含量最高值均出现在2750m针阔混交林生态系统，最低值出现在3650m杜鹃矮曲林生态系统。地被层植物平均Hg含量最高值则出现在3100m暗针叶林生态系统，最低值也出现在3650m杜鹃矮曲林生态系统。同一典型生态系统以地被层Hg含量要高于乔灌层。就同一植物的不同组织或器官来看，叶中Hg含量要明显高于枝中Hg含量，凋落叶或老叶中Hg含量要高于新鲜叶中Hg含量。 2、垂直带不同海拔典型生态系统土壤与凋落物中Hg含量特征土壤各层Hg含量和凋落物中Hg含量均随着海拔的升高表现出先增加后减少的趋势，土壤表层与底层Hg含量最高值分别出现在2750m针阔混交林生态系统和3100m暗针叶林生态系统。就同一土壤剖面而言，土壤表层（O层和A层）Hg含量要显著高于底层（B层和C层）Hg含量，主要与表层有机质含量较高有关。 3、垂直带不同海拔典型生态系统活植物体Hg贮量特征不同海拔生态系统活植物体Hg的总贮量随海拔升高表现为先增加后减少的趋势，在2750m针阔混交林生态系统达到最高值668.014μg·m-2，最低值出现在3650m杜鹃矮曲林生态系统，Hg总贮量为98.103μg·m-2。乔木层是生态系统活植物体部分Hg的主要贮存单元（65%—75%），决定着生态系统活植物体Hg贮量动态。其次是地被层（20%—27%），草本层和灌木层Hg贮量所占的比例最小，但是3650m杜鹃矮曲林的灌木层除外（72%）。 4、垂直带不同海拔典型生态系统土壤与凋落物中Hg贮量特征如果将所有土壤层次均考虑在内，则土壤总Hg贮量在不同海拔的分布大小为：3100m>>2250m>2750m>3650m,如果不考虑土壤基质对总Hg贮量的影响，仅考虑表层土壤总Hg贮量在不同海拔的分布情况则为：3100m>2750m>3650m>2250m。随着土壤剖面向下，土壤Hg贮量也越高。凋落物中Hg贮量随海拔增加呈现出先增加后减少的趋势，其中3100m和2750m生态系统凋落物Hg贮量要显著高于2250m与3650m生态系统凋落物的Hg贮量。 5、垂直带不同海拔典型生态系统总Hg贮量特征及其在各个组分的分配贡嘎山东坡垂直带总Hg贮量在不同海拔生态系统的分布以3100m峨眉冷杉暗针叶林为最高，达89.123mg·m-2,其余不同生态系统总Hg贮量相差不大，约为3100m生态系统总Hg贮存量的1/3。土壤是不同典型生态系统中的Hg的主要贮存库（>95%），活植物体和凋落物中Hg贮量占生态系统总Hg贮量的比例相当，在0.2%—2.3%之间。其中2750m生态系统活植物体与凋落物中Hg贮量占Hg总贮量的比例相对于其他海拔生态系统为最高，3650m生态系统则最低。土壤中Hg贮量占总Hg贮量的比例与活植物体和凋落物趋势相反。;
Human activities have caused global pollution of heavy metals since the Industrial Revolution. As one of the most toxic elements, mecury has been widely concerned for its accumulation in the environment， which can be very harmful to human health and ecosystem security. The Gongga Mountain is located in the east of the Qinghai-Tibet Plateau, China. It’s alpine ecosystems was very sensitive to the mecury input, and can be a good probe for monitoring regional and national scale changes of environment. In this study, four typical forest ecosystems in this area were selected. Mecury concentrations of representative dominant species and various soil layers belong to different ecosystems were measured. Moreover, mecury storage and distribution of each component from the ecological system as well as the main factors causing such differences were also analyzed. This article can help comprehensively disclose the biogeochemical behavior of mecury in the mountain ecosystems. The main research results are as follows:1. Characteristics of mecury contents in living biomassMecury contents of dominant hardwood species in different altitudes was the highest at the 2750m mixed broadleaf-conifer forest ecosystem, while the lowest appeared at the 3650m azalea elfin wood ecosystem. In each ecosystem, the mecury contents of the ground layers were higher than those in trees and shrubs. As for mecury contents in organs and tissues of the same species, mecury contents in leaves were higher than those in twigs, while the older leaves can concentrate more mecury.2. Characteristics of mecury contents in soils and littersMecury contents in different soil layers and litters decreased before increased first. The highest value of the upper soil layers and the bottom layers appeared at the 2750m mixed broadleaf-conifer forest ecosystem and the 3100m dark coniferous forest respectively. In terms of the same soil profile, mecury contents of the upper soil layers were significantly higher than the bottom layers due to the high concentrations of organic matter in the upper layers.3. Characteristics of mecury storage in living biomassMecury storage of the living biomass in different altitudes show a trendency of decreasing after increasing first. The highest mecury storage of the living biomass appeared at the 2750m mixed broadleaf-conifer forest ecosystem, with a value of 668.014μg·m-2, while the 3100m dark coniferous forest stores the least mecury, with a value of 98.103μg·m-2. Tree layers were the main layers storing the most mecury（65%—75%）,determing the dynamics of the mecury storage in living biomass. secondly was the ground layer（20%—27%）, Herb layer and the shrub layertook up the least proportion of all except the 3650m azalea elfin wood ecosystem, in which the mecury storage percentage of the shrub layer was about 72%.4. Characteristics of mecury storage in soils and littersIf all the soil layers were taken into consideration, the distribution of total soil mercury storage in different ecosystems can be ranged as: 3100m>> 2250m> 2750m > 3650m; without considering the influence of bottom soil, the total mercury storage of the surface soil were distributed in the order of: 3100m > 2750m > 3650m > 3650m. Moreover, the deeper the soil profile, the higher the soil mercury storage.Mecury storage in litters also present the trend of increased after decreased first with the increase of altitude. Litter mecury storages in the 3100 m dark coniferous forest ecosystem and the 2750m mixed broadleaf-conifer forest ecosystem seem to be larger than those in the 2250m evergreen and deciduous broadleaved mixed forest and the 3650m azalea elfin wood ecosystem.5. Storage and distribution of mecury in different ecosystemsGenerally speaking, total mecury storage of the whole ecosystem was the highest in the 3100m dark coniferous forest, with a value of 89.123mg·m2. Total mecury storages in other three ecosystems varied little, accounting for about one third of that in dark coniferous forest ecosystem. Most of the mecury was stored in the soils(>95%), the proportion of mecury storage in living biomass and the litters were almost the same, ranging from 0.2%—2.3%. Comparing with other ecosystems, the highest proportion of litters and living biomass appeared at the 2750m mixed broadleaf-conifer forest ecosystem, while the lowest proportion was at the 3650m azalea elfin wood ecosystem. A completely different trendency can be seen at the soil mecury storage proportions.
|杨丹丹. 贡嘎山东坡垂直带不同典型生态系统汞含量与汞贮量差异[D]. 北京. 中国科学院大学,2016.|
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