共查询到18条相似文献，搜索用时 125 毫秒
1.
贡嘎山东坡林地土壤的诊断特性与系统分类 总被引：10，自引：0，他引：10
贡嘎山东坡寒区林地在海拔2200～3650m的典型土壤,其土壤诊断层和诊断特性主要有暗瘠表层、漂白层、雏形层、石质接触面特征、常湿润土壤水分状况和寒冻、寒性、冷性或温性土壤温度状况.由于泥石流和冰川堆积物对所发育土壤性状有很大影响,提出了划分泥石流岩性特征和冰碛物岩性特征及其诊断指标.根据本区土壤诊断层和诊断特性,按照中国土壤系统分类对研究区典型土壤进行了检索,在分类中首次根据泥石流岩性特征和冰碛物岩性特进行了土壤系统分类. 相似文献
2.
安徽淮北平原钙质结核土分布及成因年代研究 总被引：4，自引：0，他引：4
提出了钙质结核土的概念,并详细研究了安徽淮北平原钙质结核土的分布规律、成因年代以及钙质结核的类型。通过地质调查、试验和勘探,并参阅工程勘察报告和文献资料,分析了安徽淮北平原钙质结核土的埋藏和分布规律,绘制了淮北平原钙质结核土平面分布图及典型地层剖面图。钙质结核土分布在淮北平原河间地块、洼地及黄泛平地上,结核层的埋藏标高与地面标高变化基本一致。在剖面上,从上到下,钙质结核一般为雏形钙质结核、完形钙质结核和钙质硬磐层,其粒径和含量随深度增大而增大,在常年地下水位附近常形成钙质硬磐层;根据14C测定的年龄分析,在剖面上,雏形钙质结核、完形钙质结核和钙质硬磐层三种形态的钙质结核年龄逐渐增大 相似文献
3.
石灰土发育过程中土壤腐殖质组成及其与土壤钙赋存形态关系 总被引：6，自引：2，他引：4
选取桂林典型石灰土不同发育阶段土样(黑色石灰土、棕色石灰土、黄色石灰土),对土壤中腐殖质组成、土壤钙的形态及其含量进行测定。结果显示:(1)石灰土发育过程中,黑色石灰土、棕色石灰土、黄色石灰土总碳量分别为230.15mg/g、37.49mg/g、17.94mg/g,胡敏酸所占比例分别为31.94%、9.44%、7.25%,富啡酸所占比例为1.04%、36.14%、66.16%,胡敏素为67.02%、54.41%、26.59%;(2)黑色石灰土、棕色石灰土、黄色石灰土中土壤钙全量分别为21486.66mg/kg、6913.33mg/kg、5540.17mg/kg,且三种土壤中均是酸溶态所占比例最高,分别为57.58%、74.69%、80.83%,其次为可还原态、残渣态和可氧化态;(3)相关性分析表明,土壤钙及其各形态均与土壤有机碳总量、胡敏酸、胡敏素成正相关关系,与富啡酸成负相关关系,土壤腐殖质组成及其含量在很大程度上影响着土壤钙含量及赋存形态。 相似文献
4.
荆门弱膨胀土的胀缩与渗透特性试验研究 总被引：1，自引：1，他引：0
以荆门弱膨胀土为研究对象,开展了完整的胀缩与渗透特性试验,获得了5种不同压实度下膨胀土及其石灰改良土的胀缩与渗透特征。结果表明：膨胀土的膨胀力-干密度关系可用幂函数表达,而无荷膨胀率、有荷膨胀率、体缩率与干密度均非单调关系;由于压实与膨胀效应的耦合作用,95%压实度下膨胀土的无荷膨胀率、有荷膨胀率和体缩率均较小,若直接利用膨胀土进行路基与地基填筑,该压实度下土样不仅具备较大的刚度与强度且胀缩变形较小。经石灰改性后,膨胀力与湿胀变形基本消除,干缩变形大幅降低,胀缩总率仅为0.7%。膨胀土与石灰土渗透系数均很小,且都随干密度的增大而降低,其与干密度的关系仍可用幂函数描述;石灰土的渗透系数大于相应压实度下的膨胀土;而当二者干密度相近时,渗透系数接近。 相似文献
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粉土因毛细水发育表现出较强冻胀特性,在冻土区建设中需关注其冻害问题。土中掺入石灰是一种常见的化学土质改良方法,但石灰对粉土的冻胀特性影响尚不清晰。为研究石灰改良粉土的冻胀特性和效果,进行了开敞系统下的一维冻胀试验,分析不同掺灰量下的温度场、变形场和水分场变化规律和机理。研究发现:土样随掺灰量增大,其冻结深度先增大后减小,冻胀量和补水量持续减小,而冻胀率先减小后增大,各指标呈不同变化规律,冻胀特性复杂;一定条件下提高掺灰量可减小冻结深度和冻胀量直至低于素土,土样抗冻性提高;而随着掺灰量变化,石灰改良粉土的冻胀率始终高于素土,土样抗冻性改良不显著。因此,在实际工程中,不能仅通过单一指标评价石灰改良粉土的效果,需结合冻结深度、冻胀量和冻胀率三个指标,综合评价石灰对粉土抗冻性的改良效果。 相似文献
7.
合徐高速公路膨胀土路基填料的试验研究 总被引：1，自引：0，他引：1
膨胀土路基掺石灰率应通过物理与力学性质、胀缩性、水稳性等试验来确定，本文对合徐高速公路(合肥段)膨胀土路基填料不掺石灰和掺石灰处理后的胀缩性及物理、力争性质进行了试验研究，得出了掺石灰对改善膨胀土路基填料工程性质的影响，并对不掺石灰和掺石灰处理后的填料进行了膨胀及收缩变形量的估算，论述了膨胀土特性及处理方法，供同行参考。 相似文献
8.
青藏高原典型寒冻土壤对高寒生态系统变化的响应 总被引：12，自引：5，他引：7
高寒生态系统对全球变化非常敏感,以青藏高原腹地的长江黄河源区为研究区域,利用多期遥感TM数据和生态样带调查数据,提出生态综合指数方法.应用土壤结构、组成与水理特性等物理指标和土壤化学性质与养分含量指标,系统分析了青藏高原典型寒冻土壤如钙积寒性干旱土、简育寒性干旱土、草毡寒冻雏形土以及简育寒冻雏形土等对高寒生态系统变化的响应特征.结果表明:随着气候变化,主要高寒生态系统如高寒草甸、高寒草原以及高寒沼泽草甸等显著退化,寒冻土壤表层呈现明显粗粝化,草毡寒冻雏形土以及简育寒冻雏形土表层土壤细粒物质流失38.7%,土壤孔隙度和容重增加;高寒草甸土壤表层饱和导水率随综合生态指标值降低而急剧增大,当植被覆盖度<50%以后,土壤表层水分集聚现象不再存在,高寒草原土壤饱和导水率变化不明显;高寒草甸与高寒草原土壤的有机质和全氮含量均随生态指数减少而分别呈现抛物线和指数曲线形式减少.随着气候变暖和人类活动干扰的加剧,高寒草地生态系统变化将可能导致寒冻土壤环境持续退化并对高原草地碳循环产生重要的影响. 相似文献
9.
钙质土因其颗粒形状不规则、易破碎、高孔隙比等特征,其力学性质较为特殊。采用室内大型直接剪切试验设备,对取自南海珊瑚礁和三亚岸礁的粗颗粒钙质土进行了直剪试验,研究了粗颗粒钙质土在不同含水率、不同密度和不同矿物组成条件下的钙质土剪切特性。结果表明,粗颗粒钙质土表现出与常规无黏性土截然不同的力学性质,即（1）与石英砂相比,表观黏聚力较大,内摩擦角较高,软化性较弱;（2）表观黏聚力随着平均粒径的增大而增大,内摩擦角随着干密度的增大而增大;（3）与峰值强度相比,土体剪切破坏后其残余强度的表观黏聚力锐减而内摩擦角仅略有减小。研究成果可为岛礁工程建设提供借鉴,也可为其他粗颗粒土的研究提供参考。 相似文献
10.
岩溶区典型石灰土Cd形态指示意义及风险评价——以桂林毛村为例 总被引：1，自引：0，他引：1
为了了解岩溶区石灰土中重金属Cd形态分配特征及富集情况,在桂林毛村采集了3种处于不同发育阶段的黑色、棕色和红色石灰土进行研究。通过原子光谱仪测试了Cd质量分数,运用改进的Tessier分析法测定了3种石灰土中Cd的可交换态(EXC)、碳酸盐结合态(CAB)、铁锰氧化物结合态(OXI)、有机结合态(ORG)、残渣态(RES)5种形态,并对其指示意义及风险进行了分析与评价,结果表明,3种石灰土中Cd质量分数从大到小依次为早期黑色石灰土、中期棕色石灰土、晚期红色石灰土。形态测试结果表明:黑色石灰土和棕色石灰土中Cd形态以铁锰氧化态和残渣态为主,占土壤Cd质量分数的63%以上,且5种形态质量分数从大到小顺序均为铁锰氧化态、残渣态、可交换态、碳酸盐结合态、有机结合态;红色石灰土Cd形态以残渣态为主,占土壤Cd质量分数的76%,形态分配特征从大到小为残渣态、铁锰氧化态、可交换态、碳酸盐结合态、有机结合态。Cd稳定度和富集程度评价结果表明:在黑色石灰土、棕色石灰土和红色石灰土中Cd稳定度逐渐减小,环境二次释放风险逐渐降低;富集程度从大到小依次为黑色石灰土、棕色石灰土、红色石灰土,其中Cd在黑色石灰土中呈显著富集状态,在棕色石灰土中呈中度富集状态,在红色石灰土中呈轻微富集状态。潜在生态风险评价和健康风险评价结果表明,由早期黑色石灰土到中期棕色石灰土和晚期红色石灰土,土壤中Cd的生态风险和健康风险均逐渐降低。研究结果可为岩溶区土壤重金属Cd污染修复与治理提供基础数据。 相似文献
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Leland H. Gile 《Quaternary Research》1977,7(1):112-132
Holocene soils of a semiarid area in southern New Mexico occur on terraces and fans in and adjacent to the mountains. The illustrative soils have formed in alluvium derived from rhyolite, monzonite, and sedimentary rocks, mainly limestone.A large arid basin occurs downslope from the mountains. In the arid-semiarid transition, the effect of a gradual increase in precipitation on soil morphology is shown by Holocene soils that sensitively reflect the precipitation. Where the parent materials contain little or no carbonate, a surficial noncalcareous zone and a reddish-brown horizon of silicate clay accumulation thicken mountainward as precipitation increases. The Bt horizon is underlain by the carbonate horizon, the upper boundary of which deepens mountainward. These orographic-depth relations and soil morphology support an interpretation that some of the clay (as well as the carbonate) is of illuvial origin. In high-carbonate parent materials, a noncalcareous zone has not developed and a reddish-brown horizon of clay accumulation has not formed.In upper horizons, organic carbon increases and color darkens towards the mountains. This causes a change in soils at the categorical level of soil order; Mollisols do not occur in the arid basin downslope, where nearly all Holocene soils are either Aridisols or Entisols. In the semiarid zone, however, most Holocene soils are Mollisols. Thick, dark A horizons have formed in many of these soils. The thickness of these horizons is attributed primarily to episodes of sedimentation during soil development. Some Holocene Aridisols also occur in the semiarid zone. Generally these are on narrow ridges, where the mollic epipedon has been truncated or did not form.In some terrains the soil-geomorphic relations are complex and Holocene soils may be above or at the same elevation as adjacent, much older soils. In such situations, when the morphological range of the various soils has been determined, soil morphology may be used to distinguish the Holocene soils and surfaces from their older analogs. 相似文献
12.
Holocene soils and soil-geomorphic relations in an arid region of southern New Mexico 总被引：1，自引：0，他引：1
Leland H. Gile 《Quaternary Research》1975,5(3):321-360
A study area in an arid region of southern New Mexico is in basin-and-range topography and includes both a river valley and a closed basin. Holocene soils occur in valley fills and low terraces between Pleistocene fans, in and near drainageways on the fan-piedmont, on ridges, and in dunes. Holocene soils suggest the character of initial development in soils that are much older and more complex, and record the beginnings of various soil horizons. Noncalcareous brown or reddish brown B horizons have formed in low-carbonate parent materials of stable sites. Incipient development of the argillic horizon and the Haplargids occurs at stable sites in very gravelly materials that are about 1–2000 yr old. The cambic horizon and Camborthids occur in adjacent low-gravel materials of the same age. The argillic horizon occurs continuously in soils of earliest Holocene, particularly in very gravelly materials. Where soils have been truncated, as in areas affected by landscape dissection, argillic and cambic horizons are usually absent and the soils are Torripsamments, Torriorthents, or Torrifluvents depending on content of sand, gravel, and organic carbon. In high-carbonate parent materials, noncalcareous, reddish brown B horizons have not formed at any time in the Holocene. Most of these soils are Torriorthents or Torrifluvents although an incipient calcic horizon has formed in some of the oldest Holocene soils; the latter are Calciorthids. Horizons of carbonate accumulation are the best and most common pedogenic indicators of soil age. Stage I carbonate horizons are a major feature of pedogenesis in the Holocene. Because of additions of carbonate from the atmosphere, carbonate horizons are morphologically similar whether they have formed in high or low-carbonate alluvium. The carbonate accumulations are illuvial.Some Holocene deposits apparently resulted from changes in climate. Others, such as the youthful deposits of coppice dunes, apparently were caused by man's introduction of cattle and subsequent overgrazing and seed dispersal. 相似文献
13.
中国黄土中古土壤的发生学研究 总被引：4，自引：2，他引：4
应用形态学、微形态学、化学和矿物学研究了中国黄土中古土壤的发生学性状和成土过程。离石黄土(中更新世)中古土壤为发育程度(碳酸盐淋溶和粘化)不同的褐土型土壤。马兰黄土(晚更新世)中为生草过程强和粘化过程稍弱的灰褐土型土壤。全新世黄土中为碳酸盐淋溶和粘化过程均弱的弱度发育的碳酸盐灰褐土型土壤。午城黄土(早更新世)中可能是棕褐土。本文还探讨了黄土中古土壤在时间和空间上的演替和分类问题。 相似文献
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Genesis of pedons with discontinuous argillic horizons in the Holocene loess mantle of the southern Pampean landscape,Argentina 总被引：1，自引：0，他引：1
《Journal of South American Earth Sciences》2007,23(1):30-45
Soil development in the plain landscape of the southern Argentinean Pampa is related to pulses of aeolian accretion of calcareous loess during the Holocene epoch. Such plain relief is associated with landform stability that favors pedogenesis. In some sectors of the Holocene loess mantle, detailed soil surveys show a great variability of soil morphology in short distances (<7 m), such that pedons with Bt horizon (Ap-Bt-C-2Ckm) coexist with pedons with an AC horizon (Ap-AC-C-2Ckm) in a plain landscape, within identical loess parent material over a tosca layer (2Ckm-calcrete-petrocalcic horizon), and in a similar pedoclimate. This article studies the origin of this spatial variation. Loess parent materials directly overlie the relic tosca layer, exhumed after erosion of preexisting soils of the Late Pleistocene. The contrast in soil morphology between the petrocalcic horizon and the overlying Holocene soils reflects the effect of polygenesis. The complex soil spatial distribution pattern over the tosca layer appears unrelated to its paleomicrotopography, because soils with Bt horizons are identified in positive and depressed microlandforms of the tosca. The absence of Bt horizons might be caused by formerly intense biological activity related to a stable pattern of two natural vegetation covers or a surface paleomicrotopography that supported distinct vegetation types depending on the soil moisture in each paleomicrolandform. 相似文献
16.
Péter Sipos 《Central European Journal of Geosciences》2009,1(4):404-415
The sorption parameters of Cu, Zn and Pb are related to the composition of the different genetic horizons of a Luvisol profile in batch sorption experiments. The affinities of metals towards the soil samples from different horizons followed the same sequence, e.g. Pb≥C>>Zn. By far the highest metal retention was found in the Ck horizon due to the alkaline conditions. It is followed by the A horizon with its high organic matter content, while the lowest sorption capacity was found in the Bt horizon. In the horizons free of carbonate, primarily Pb and Cu were immobilized. The studied soil can be characterized by high amount of organic matter, clay accumulation horizon, as well as calcareous subsoil. This kind of profile development makes soils able to immobilize a significant metal pollution. 相似文献
17.
The interactions of organic matter and minerals contribute to the capacity of soils to store C. Such interactions may be controlled by the processes that determine the availability of organic matter and minerals, and their physical contacts. One of these processes is bioturbation, and earthworms are the best known organisms that physically mix soils. Earthworms are not native species to areas previously glaciated, and the introduction of earthworms to these regions has been associated with often dramatic changes in soil structure and geochemical cycles. The authors are studying C mineral interaction along an approximately 200 m long earthworm invasion transect in a hardwood forest in northern Minnesota. This transect extends from the soils where earthworms are absent to soils that have been invaded by earthworms for nearly 30–40 years. Pre-invaded soils have an approximately 5 cm thick litter layer, thin (～5 cm) A horizon, silt rich E horizon, and clay-rich Bt horizons. The A and E horizons formed from aeolian deposits, while the clay-rich Bt horizons probably developed from underlying glacial till. With the advent of earthworm invasion, the litter layer disappears and the A horizons thicken at the expense of the O and E horizons. In addition, organic C contents in the A horizons significantly increase with the arrival of earthworms. Simultaneously, measured mineral specific surface areas suggest that minerals’ capacities to complex the organic matter appear to be greater in soils with active earthworm populations. Based on the data from two end member soils along the transect, mineral specific surface areas in the A and E horizons are larger in the earthworm invaded soil than in the pre-invasion soil. Additionally, within < 5 a of earthworm invasions, A horizon materials are turned from single grain to a strong medium granular structure. While A horizon organic matter content and organic C-mineral complexation increase after earthworm invasion, they are also more vigorously mixed. This growing data set, when ultimately combined with ongoing measurements of (1) the population dynamics of earthworms along the invasion transect, (2) C-mineral association (via surface adsorption and physical collusion in mineral aggregates) and (3) dissolved organic C will show how and how much soil capacity to store C is affected by burrowing organisms, which are often the keystone species of given ecosystems. 相似文献
18.
It is often difficult to establish in the field the origin of the B horizon of buried truncated palaeosols. However, infrared spectral configurations of electrodialyzed humic acids can be used as a diagnostic tool. Decreased absorption on passing from 2500 to 1800 cm-1 indicates the presence of a chernozemic B horizon. The difference was explained on the basis of the conditions that existed at the time of the formation of these horizons. Burial did not change the structure of the humic substances responsible for the infrared spectral configurations. 相似文献