IMHE OpenIR  > 山地表生过程与生态调控重点实验室
海螺沟冰川退缩区土壤矿物演化与土壤发育
Language中文
杨子江
Thesis Advisor吴艳宏
2015
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name硕士
Degree Discipline自然地理学
Keyword土壤发育 土壤发育速率 土壤矿物风化 X射线衍射分析
Abstract全球气候变化造成高山冰川退缩,更多的成土母质开始出露并逐渐发育为土壤。受冻融、雨雪融水渗透和植被群落演替作用的影响,冰川退缩区经历了成土作用的早期过程。因此,研究高山和亚高山环境下土壤发育早期阶段的矿物风化和发育过程有助于揭示高山和亚高山环境对土壤矿物风化、土壤发育速率的影响,丰富土壤发育理论,阐明土壤早期发育机制。 贡嘎山东坡的海螺沟冰川退缩迹地上形成的较完整的120年左右土壤演化序列,是研究山地环境中土壤发育初期土壤理化性质变化、土壤矿物风化以及黏土矿物演化的理想场所。在海螺沟土壤序列上,根据成土母质出露时间,本研究设置6个样点,分别代表2010年、1980年、1970年、1958年、1930年、1890年出露的成土母质。根据土壤产状及颜色等特征将土层划分为O层(半分解的凋落物层)、A层(有机质富集层)和C层(母质层)。采集到的土壤进行理化性质分析(土壤容重测定、机械组成分析、土壤pH值测定、有机质测定、阳离子交换量和交换性盐基离子、土壤元素总量),使用X射线衍射(XRD)进行土壤矿物组成分析(矿质土壤和黏土),并结合当地的地质、气象和植被数据,分析土壤成土过程、土壤发育速率以及土壤矿物演化。主要的结果和结论如下: 1、海螺沟土壤序列上母质均质性较好,土壤发育主要包括有机质累积和盐基离子淋溶,地表植被的演替加速此过程进行。随成土母质出露时间增加,土壤理化性质发生变化:土壤容重和pH值逐渐降低,而土壤表层的有机质含量逐渐上升,显示出土壤逐渐发育的过程。海螺沟土壤O层的阳离子交换量随土壤发育逐渐上升,而盐基饱和度逐渐下降,交换性K+上升。CEC的变化受到有土壤机质的影响。海螺沟土壤中K、Ca、Na、Mg四种元素随土壤发育均呈迁移淋失状态,受土壤pH值变化影响,土壤中Fe和Al元素也随土壤发育时间增加而减少。受地表植被快速演替的影响,海螺沟土壤具有较高的土壤发育速率,超过380 t km-2 a-1,土壤发育速率随母质出露时间的增加而下降。 2、伴随着土壤元素的迁移流失过程的,是土壤中原生矿物的风化过程。海螺沟土壤中主要的矿物组成以硅酸盐矿物为主,包括石英(24.5%)、斜长石(28.5%)、钾长石、普通辉石、角闪石、黑云母、绿泥石和蛭石;并有少量的碳酸盐矿物方解石(<8%)和白云石(<2.3%)和磷酸盐矿物磷灰石(<2.1%)。土壤中长石、角闪石、黑云母矿物含量较高,呈新发育土壤特征。随土壤发育,土壤A层方解石在土壤发育到52年时便几乎消耗殆尽,受生物化学作用影响形成草酸钙石。土壤中的角闪石、黑云母、磷灰石随土壤发育时间增加而逐渐下降。地表植被不仅通过在生长过程中分泌有机酸降低土壤pH直接促使表层土壤矿物风化,还通过植被演替加速对矿物风化。 3、对土壤中黏土矿物的分析表明,海螺沟土壤序列中的黏土矿物主要是云母族矿物、蒙皂石、云母/蒙皂石混层矿物以及绿泥石、高岭石为主。土壤中的绿泥石和高岭石很可能直接继承于成土母质。土壤中云母族矿物以三八面体矿物为主,很有源自成土母质中的黑云母。随土壤发育,土壤A层中云母族矿物因风化而晶层破碎加剧,表现出逐渐从三八面体矿物向二八面体矿物(伊利石)过渡的趋势。土壤中的化学环境有利于云母族矿物向蒙皂石演化,在演化的过程中形成了过渡产物云母/蒙皂石混层矿物,混层矿物在演化中逐渐从无序混层结构变为有序混层结构。
Other AbstractGlobal climate change causes glaciers continuously retreat in alpine area, leaving more parent materials exposed to weathering and pedogenesis. Glacial retreat areas experienced early stages of pedogenesis due to freezing and thawing processes, dilute waters (melt waters and rain/snowmelt) and plant succession. Thus, studying mineral weathering and soil development processes in the early stages of pedogenesis could reveal mineral weathering and soil development rate affected by mountain environment, enrich the content of soil development field as well as illustrate the mechanism in early stages of pedogenesis. The Hailuogou chronosequence, formed at the east slope of Gongga Mountains, has gone through approximately 120 years of soil development and formed a fairly completed soil succession sequence, which could expected to be a ideal place to study soil physical and chemical properties variation, soil mineral weathering and clay mineral evolution. Six sampling sites were set up in Hailuogou chronosequence, representing 0 yr, 30 yr, 40 yr, 52 yr, 80 yr and 120 yr after the retreat of the glacier. According to the occurrence of soil and the color feature, soil profiles were divided into O horizon (half decomposed litter horizon), A horizon (humus horizon) and C horizon (parent material horizon). Measurement including soil physical and chemical property ( bulk density, particle size analyses, soil pH, soil organic matter, cation exchange capacity and exchangeable base cations, total element content ), X-ray diffraction (XRD) analysis for bulk soil and clay particle. Those measurements and local bedrock, meteorology, plant data were utilized to study pedogenesis, soil development rate and soil mineral evolution. The result and conclusion are as follows: 1、The total elements contents of parent material horizon along Hailuogou chronosequece indicated that this area is quite homogenous. Organic matter accumulation and base cation leaching were two dominant pedogenic processes occurring along Hailuogou chronosequence, and the processes were accelerated by plant succession.In the approximately 120 years of soil development, soil bulk density and pH kept continuously decreasing while soil organic matter content kept increasing, Indicating soil forming processes. In the O horizon along Hailuogou chronosequence, soil exchangeable cation content increased from 249.43 mmol kg-1 to 531.42 mmol kg-1, while the base saturation percentage drops from 23.8% to 10.1%, and the content of exchangeable K+ kept increasing The soil exchangeable base cation was affected by soil organic matter. 2、Soil organic matter accumulation and base ions leaching were the two major pedogenesis characteristics along Hailuogou chronosequence. K, Ca, Na, Mg, Fe, Al were relatively removing out from the soil chronosequece during the 120 years of soil development. The soil development rates at all sites were above 380 t km-2 a-1 along the Hailuogou chronosequence, and reached 700 t km-2 a-1 as the highest value. The soil development rate was considerable high due to fast plant succession along chronosequence. Soil development rate decreases with the increasing parent material exposing time. 3、Along with the elements transportation, is the soil primary mineral weathering process. Soil minerals wrer dominated with silicates (about 90%), including quartz (24.5%), plagioclase (28.5%), K-feldspar, augite, hornblende, biotite, chlorite and vermiculite, and some carbonates, like calcite (< 8%) and dolomite (< 2.3%), and phosphate mineral apatite (< 2.1%). The soil in the area was fairly high in content of feldspar, mica and hornblende, which is the feature of entisol. As the pedogenesis proceeded, after 52 years of exposure, calcite in the parent material began to transform into calcium oxalate. Correlation analysis showed that the contents of hornblende, apatite, biotite significantly decreased with soil development (p<0.01). Surface vegetat
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/14131
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
Recommended Citation
GB/T 7714
杨子江. 海螺沟冰川退缩区土壤矿物演化与土壤发育[D]. 北京. 中国科学院大学,2015.
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