IMHE OpenIR  > 山地表生过程与生态调控重点实验室
我国主要山地森林土壤中铅的分布特征及来源解析
Alternative TitleDistribution Characteristics and Source Identification of Lead in Mountainous Forest Soils on the Mountains in China
向仲香
Subtype硕士
Thesis Advisor吴艳宏
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline自然地理
KeywordPb 苔藓监测 Pb同位素 来源解析 山地森林土壤
Abstract铅(Pb)是不能够被生物降解而且具有潜在生态危害的重要污染物,Pb污染研究已经成为当前环境领域的热点问题之一。山地生态系统与低海拔地区相比具有较大的海拔差异,从而形成了独特的地形、气候、植被分布等特征,这些因素影响了Pb在山地系统中的分布。进入到大气中的Pb能够吸附于细颗粒物,在气流的影响下发生远距离的大气传输,最终可以在高山土壤中累积;另一方面,山地生态系统,尤其是高山生态系统,是物质循环的起点,一旦山地土壤遭受Pb的污染,将对当地乃至下游生态系统造成重要影响。我国是个多山的国家,但目前针对山地土壤Pb的研究相对缺乏。本研究选取我国30个主要山地森林系统为研究区,通过采集土壤剖面(有机层、矿物表层和母质层)样品(1530个)和优势苔藓样品(156个),调查Pb在我国山地森林土壤中的空间分布特征;利用Pb同位素示踪、苔藓监测、统计分析等手段判识Pb的来源;结合区域气候和人类活动特征,阐明影响森林土壤中Pb分布的关键因素。主要结果和结论如下:(1)我国主要山地森林土壤中Pb的浓度显著低于农田、城市和矿区土壤。除南岭、鼎湖山、龙泉山外,山地森林土壤母质层(C层)中Pb的浓度与其所在区域的土壤元素背景值不存在显著性差异,因此研究选择土壤母质层Pb的浓度作为当地背景值。地累积指数和单因子污染指数结果表明我国主要山地森林土壤受到了Pb的污染,但污染水平整体上较低,潜在生态风险指数表明所研究的山地土壤均属于轻微风险水平。除大兴安岭、五指山、赛罕乌拉三座山地处于未受污染水平,苔藓中Pb均处于中等污染水平。(2)在土壤剖面分布上,Pb的浓度(mg/kg)整体呈现出O层[5.59~522(51.7±2.1)] > A层[5.70~974(43.8±2.3)] > C层[7.43~373(30.4±1.6)]的特征。小兴安岭、大别山、神农架、鳌山和哀牢山土壤O层和A层中Pb的浓度随着海拔的升高呈现出显著上升趋势,大兴安岭和太白山则呈现出显著下降趋势,其余山地并未呈现出显著的海拔梯度变化。空间分布上,土壤O层Pb的浓度南方整体上高于北方,东部高于西部,呈现从东南向西北递减的趋势。苔藓中Pb浓度[3.00~390(52.6±3.4)](mg/kg)高于土壤。在海拔上,小兴安岭、神农架和哀牢山苔藓中Pb的浓度随着海拔的升高而升高,大兴安岭和贡嘎山则呈现显著下降的趋势。空间分布上基本与土壤相同,即东部高于西部,南方高于北方。其中,土壤中Pb的浓度在25°N~35°N之间呈现一个高值分布带,苔藓则表现在25°N~30°N之间。(3)通过统计分析、Pb同位素示踪和苔藓监测等手段,土壤O层和A层中Pb在一定程度上受到了人类活动的影响,而C层中Pb主要受到母岩风化的影响。人类活动来源的Pb主要包括化石燃料燃烧、矿物的开采与冶炼等。苔藓中人为Pb浓度(mg/kg)[2.2~182.3(41.0±2.9)]大于土壤O层[0.1~287.5(38.3±1.8)]和A层[0.4~241.1(20.3±1.3)]。人为Pb在低海拔富集表明主要受到近距离的人类活动即当地人类活动的影响,而在高海拔地区富集则主要受到远距离大气输送的Pb的影响。(4)影响我国主要山地森林土壤中Pb分布的主要因素包括了母岩风化、湿沉降、地形、植被分布、土壤理化性质和人类活动等。其中,温度较高和降水量较大不仅加快母岩风化速率影响土壤垂直剖面上Pb的分布,而且湿沉降越大往往伴随着土壤和苔藓中Pb的浓度也较高。地形对土壤Pb的分布主要与所处的迎风坡或背风坡的位置相关,一般迎风坡温度高、降水多,大气沉降量较大,导致Pb的富集相对较高。土壤理化性质对Pb的影响包括土壤类型、SOC、pH等。植被对Pb分布的影响体现在吸收作用、归还效应、林冠拦截和淋滤作用。本研究对受人为影响较小的偏远山地森林生态系统开展了土壤Pb的赋存特征研究,探讨了地形、植被、气候和人类活动等因素对其累积的影响,不仅为工业区、农业区以及城市区Pb污染研究提供区域上的背景参考,而且可以揭示不同区域人类活动对Pb污染的贡献程度。将来可结合大气传输模型开展高山生态系统对大气Pb传输的生态屏障效应研究。
Other AbstractLead (Pb) is a major pollutant which is cannot be biodegradable and has potential ecological risk. The Pb pollution research has become one of the most important issues in the field of environmental studies. Mountain ecosystems feature larger altitude gradient differences than those in low altitude areas, which forms the unique topography, climate, vegetation distribution and so on. These natural factors influence the distribution of Pb in the mountain system. Pb attached on fine particulates can be exported to the alpine mountain soils through long distance atmospheric transportion, while the mountain ecosystems, especially the alpine mountain ecosystem are initials of substance cycles. Once the mountain soils suffered from Pb pollution, they will pose threats to the local and downstream ecosystems. China is a mountainous country, but Pb researches in these mountainous areas are still poor.30 main mountainous forest systems in China were selected as the study areas. Soil profiles (organic horizon, mineral surface horizon and parent material horizon) (n=1530) and dominant moss samples (n=156) were collected to investigate the spatial distribution of Pb in the mountainous forest soils. The methods including Pb isotope fingerprint, moss biomonitoring and statistical analysis were used to distinguish sources of Pb. Moreover, the key factors of driving the Pb distribution in mountainous forest soils were explored. The main results and conclusions are as follows:(1) The Pb concentrations in the mountainous forest soils were significantly lower than the farmland soils, urban soils and mining area soils. There were no significantly differences for the Pb concentrations in different provinces between soil C horizon of mountainous forest and Pb background values, except Nanling, Dinghu and Longquan Mountains. These results indicated that geochemical background values of Pb in the forest soils are basically identical. The index of geoaccumulation (Igeo) and single factor pollution index (Pi) showed that the mountainous forest soils of whole study areas were lowly contaminate by Pb. Potential ecological risk index (Eij) showed that the mountainous forest soils displayed low risk level. The Pb concentrations appeared medium contamination level in the mosses while the mosses in Daxing, Wuzhi and Han Mountains were not contaminated by Pb.(2) The distribution of Pb in soil profiles presented O horizon [5.59-522(51.7±2.1)]>A horizon [5.70-974(43.8±2.3)] >C horizon [7.43-373(30.4±1.6)]. The Pb concentrations in O and A horizons of Xiaoxing, Dabie, Shennongjia, Ao, Ailao, Daxing and Taibai Mountains showed apparent altitude gradient distribution. The spatial distribution patterns of Pb concentrations in the O horizon displayed a decending trend from southeast to northwest China. The spatial distribution trend of Pb showed a similar distribution in the mosses. Furthermore, the higher Pb concentrations existed both in soil samples from 25°N to 35°N in the soils and from 25°N to 30°N in the mosses.(3) According to the moss biomonitoring, Pb isotope fingerprint and statistical analysis method, Pb was influenced by human activities in the O and A horizons while it was influenced by parent material weathering in C horizon. Anthropogenic Pb was mainly from the burning of fossil fuels, mineral mining and smelting, etc. Anthropogenic Pb in moss [2.2-182.3 (41.0±2.9)] was higher than in the O [0.1-287.5 (38.3±1.8)] and A [0.4-241.1(20.3±1.3)] horizons. Enrichment of anthropogenic Pb in lower altitude showed that Pb was influenced by local human activities while enrichment of anthropogenic Pb in higher altitude was mainly from long range atmospheric transport.(4) The distribution of Pb concentrations in mountainous forest soil among the study areas were influenced by rock weathering, terrain, wet precipitation, vegetation distribution, soil physical and chemical properties and human activities, etc. Higher temperature and more precipitation could increase rock weathering rates and then induced the complex Pb distribution in soils. The distribution of soil Pb was also influenced by topography. In general, higher temperature and wet precipitation on the windward slope of mountain could accumulate more Pb. Soils physical and chemical properties affected the Pb distribution including soil type, SOC, pH, etc. The uptake/adsorption capacity of plants, canopy filtering, litterfall decomposition and leaching were mechanisms that affect the distribution of Pb in soil.This study investigated the distribution of Pb in the mountainous forest ecosystems where were far from direct human activities, and discussed the main factors affecting the Pb distribution, such as topography, vegetation, climate and human activity. The result of this study could provide some reference data on background value for Pb pollution researches in industrial, agricultural and urban areas; moreover, this work revealed the contribution of human activities in different regions of China. In future, the study about ecological barrier of alpine ecosystem for atmospheric Pb transport needs to be explored combined with the atmospheric transport model.
Pages119
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24580
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
向仲香. 我国主要山地森林土壤中铅的分布特征及来源解析[D]. 北京. 中国科学院大学,2017.
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