黄土高原古土壤成土过程的特异性及发生学意义

中国西北地区 ,从中新世以来就有持续不断的风尘沉积。这种风尘沉积作用即使在气候较为湿热的古土壤发育时期也未中断。黄土上土壤发生的独特性在于成土过程与风尘沉积的同步性。这种独特的成土过程使得土壤剖面深厚而均匀 ,常呈复合性状。古土壤与下伏黄土 ,不再是土壤与母质的关系 ;古土壤的真正母质应是成土过程中不断添加的风尘物质。古土壤中并不存在埋藏A层 ,对古土壤进行A、B、C等发生学层次的划分值得商榷。由于富含碳酸钙风尘物质的不断添入 ,成土作用强度受到不断削弱 ,绝大多数古土壤的成土作用强度未达到棕壤的发育强度。     

长江中游地区第四纪红土的二元结构及古环境意义

在长江中游地区的湖南和湖北两省,选择宜昌、咸宁、常德、长沙、株洲5个第四纪红土剖面,分析第四纪红土的粒度组成特征,研究红土的成因及南方古环境的演变。结果表明,这些地区第四纪红土的粒度组成呈明显的二元结构:剖面上部(宜昌剖面0～320 cm,咸宁剖面0～220 cm,常德剖面0～270 cm,长沙剖面0～280 cm,株洲剖面0～150 cm)粒度细小而均匀,砂粒含量低,大部分小于1%;粗粉砂(又称风尘"基本粒组")相对富集,平均含量分别为34.38%、32.29%、32.48%、31.69%和31.86%。而且土壤样品粒度频率分布曲线与安徽宣城第四纪红土很相似,与镇江下蜀黄土也有明显继承性。这些特性均反映了剖面上层红土的风成特性。但研究剖面下部红土,粒度组成有明显不同:含有砾石,砂粒含量较高,不同粒度组分垂向变化明显,粒度频率分布曲线与宣城红土和下蜀黄土有显著差异,表现出明显的冲、洪积相特性。第四纪红土的"二元结构",反映了研究区域第四纪古环境的多变性和复杂性:早期红土形成后,因受间冰期湿热气候的影响,多受流水作用改造;而晚期红土更多地受风尘堆积的影响,沉积后虽经过了强烈的原位风化,但仍保留了风尘沉积的特性。     

长江下游地区下蜀黄土成土发生学研究

通过对长江下游地区一个典型剖面的系统研究,探讨了长江中下游地区下蜀黄土成土特点。研究结果表明,长江下游地区全新世最适宜期形成的古土壤层(黄棕壤)是在末次冰期下蜀黄土堆积成壤基础上的再发育,与下伏下蜀黄土之间基本具备发生学联系。     

Spurenelemente in Bodensequenzen II. Zwei Pararendzina – Pseudogley – Sequenzen aus Löß

Trace elements in pedosequences II. Two Pararendzina-Pseudogley-sequences on loess Total amounts and fractions of Cu, Zn, Pb, Cd, Co and Ni extractable in boiling oxalate (replacing dithionite for analytical reasons), oxalate at room temperature and EDTA were determined in two hydro-pedosequences on loess ranging between Pararendzina-Braunerde-Parabraunerde-Pseudogley. The pedogenic influence on the depth functions of these trace elements was much weaker in the loess soils than in those on slates of part I of this study. With a few exceptions external additions seem to be masked by soil cultivation. Clay movement (Alfisols) produced maxima of Fe and Cu in the B_t horizon. Carbonates of the parent loess contain trace elements which are released into the soil during solum formation. As long as they exist in carbonates they are hardly extractable with oxalate but with EDTA. In contrast, after pedogenic decomposition of the carbonates in the B horizon their trace elements are now oxalate but no longer EDTA extractable. In the A horizon, where organic matter is involved the trace elements are again EDTA extractable. As in the soils from slate (part I) Cd behaves more similarly to Pb than to Zn. The total element balance indicates a slight gain of Pb and loss of Zn whereas the total amount of the other elements was essentially unchanged. Generally, the more mobile fractions increased during soil formation.     

Complex pedogenesis related to differential aeolian sedimentation in microenvironments of the southern part of the semiarid region of Argentina

The aim of this paper is to explain soil genesis and spatial variability in the soil cover of a flat landscape in the southern part of Argentina's semiarid region. Soil survey data indicate random differences in the properties of soils lying within a few hundred meters of one another, as reflected in an intricate distribution pattern which cannot be explained by the climatic theory of soil genesis in a single pedogenetic cycle. This pattern is unrelated to the actual vegetation cover. The soil parent materials consist of a <2-m mantle of aeolian Holocene sediments overlying a thick plio-Pleistocene “tosca” layer (calcrete, caliche). The undulations in the tosca layer are indicative of a paleomicrorelief levelled up to the present surface after the deposition of the Holocene sediments. Soils with fine-textured sandy loess and strong development (Meridiano soil: A–Bw–Ck–2Ckm) occupied a higher position within paleomicrorelief of the tosca layer. Adjacent soils on border or intermediate positions of the petrocalcic paleosurface have more complex profiles with a relict calcic horizon (Vizcachera soil: A–C–2Ck–3Ckm) and coarser texture (silty clayey sand) in the topsoil. In the lower positions of the paleomicrorelief of the tosca layer, the silty clayey sand directly overlie the petrocalcic horizon (El Khazen soil: A–C–2Ckm). The intricate distribution pattern is due to the coexistence of older polypedon (Meridiano soil), remnants of an earlier erosion cycle complexed with two younger soils, one from partial erosion (Vizcachera soil) and the other where total erosion of earlier soils was followed by successive pulses of aeolian deposition (El Khazen soil). The distribution pattern of the three soils thus reflects a complex history involving at least three stages of landscape evolution.     

Biogenic and chemogenic calcium accumulations in Mollisols developed from loess in Argentina pampas

The morphology of pedogenic calcium accumulations, their distribution in the soil profile, and the mechanisms of their formation in Mollisols of Argentina pampas were studied in the southeast of the Buenos Aires province. The chemogenic collomorphic calcareous films and tubes and the biogenic (cyanobacterial) gypsum framboidal structures (spherulites) were detected with the use of electron microscopy. Two mechanisms of the formation of framboidal gypsum were identified: (a) the formation of crystalline gypsum crusts around less soluble minerals (calcite) by spherical colonies of cyanobacteria and (b) the inheritance of the spherical shape of gypsum pedofeatures from the framboidal pyrite concretions accumulated in marine deposits and subjected to decomposition by sulfate-reducing bacteria. It is probable that the cyanobacterial gypsum accumulations are only formed in the studied soils during the dry season and are dissolved during the wet season.     

江淮流域白浆化土壤的矿物组成与化学特性的研究

对采自江淮流域的7个典型白浆化工土壤剖面不同粒级的矿物特性与化学组成进行了研究。结果表明：该区域白浆化土壤的质地为粉砂质壤土及粘壤土，粉粒含量为45%～76%。粘粒矿物以水云母为主，含量为60%～80%，继承了黄土母质的特性，土体硅铝率（Sa)与硅铁铝率（Saf）分别为7.70～14.05与6.43～10.24，而粘粒的分别为3.53～4.22和2.40～3.35。各剖面土体Sa与Saf以表层较高或最高，有明显富硅现象；而粘粒的Sa和Saf及矿物组成，颗粒组成的层次差异则表现出母质层次上的不连续性，白土层与粘化层的显著分异是由于全新世黄土性沉积物，经过冲积淤积交替更迭，加上后期淋溶淀积而成；脱硅、脱盐基和富铝化及氧化还原淋溶淀积是其重要成土过程，后一过程不同的利用方式，强度有所差别，以水稻土较强。     

中国南方金衢盆地红土多元成因的粒度证据

Six typical red clay profiles were sampled from Tangxi (TX),Langyaz (LYZ),South Shangshanwen (SSW),Xianqiao (XQ),Qijian (QJ) and Huhaitang (HHT) of Jinhua-Quzhou Basin,Zhejiang Province of China to evaluate the characteristics of grain size composition,distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China.The results showed that red clays in TX,LYZ and SSW were fine and uniform,with no>2mm gravels and little>63μm fraction.They had a high content of 10–50μm fraction,so-called"basic dust fraction",and showed unimodal distributions,which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China.All these features reflected marked aeolian characteristics of the red clays in these areas.Red clays in XQ and QJ were much coarser than those in TX,LYZ and SSW,with high contents of >63μm fraction and even containing>2 mm gravels in some layers.The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess,implying they might be derived from underlying parent rocks and had some inherited properties from bedrock.Red clays in HHT had high contents of>63μm fraction and contain many >2mm gravels in each layer.The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile,revealing its alluvial or diluvial origin in HHT.The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China.It can be concluded that grain size is an efective proxy indicator for the origin of most deposits.     

Pedogenic chlorites in podzolic soils with different intensities of hydromorphism: Origin,properties, and conditions of their formation

Minerals of the pedogenic chlorite group were studied in the clay fractions isolated from the mineral horizons of podzolic and gleyic peat-podzolic soils. In the AE and E horizons of the podzolic soil, pedogenic chlorites are thought to develop from vermiculite, whereas in the E horizon of the gleyic peat-podzolic soil, they can be formed from smectite minerals. For estimating the degree of chloritization (the degree of filling of the interlayer space of 2: 1 minerals with Al hydroxides), a numerical criterion was is proposed. The difference between the values of this criterion before and after the treatment of the preparations with NH₄F indicated that the degree of chloritization in the pedogenic chlorites decreases in the following sequence: the E horizon of the podzolic soil > the AE horizon of the podzolic soil > the E horizon of the gleyic peat-podzolic soil. Another numerical criterion was proposed to estimate the degree of polymerization of Al-hydroxy complexes in pedogenic chlorites. This criterion was based on the thermal stability of soil chlorites and represented the temperature at which an increase in the intensity of the 1.0-nm peak after heating the K-saturated preparations exceeds 50% of its initial value. According to this criterion, the degree of polymerization of the Al-hydroxy interlayers in pedogenic chlorites decreases in the following sequence: the E horizon of the podzolic soil > the E horizon of the gleyic peat-podzolic soil ≥ the AE horizon of the podzolic soil. The distinct interrelation between the soil properties and the degrees of chloritization and polymerization of the Al-hydroxy interlayers attests to the modern origin of the pedogenic chlorites.     

Soil polygenesis in the northeast part of Vladimir opolie

Soil studies in cultural landscapes of the medieval epoch within the Vladimir opolie territory on the Russian Plain suggest that virtually all automorphic soils in this area were plowed in that period. The morphology of the profiles of studied soils depends on the composition of parent materials. If the parent material represents a pedocyclith that passed through the stage of periglacial pedogenesis in the Late Pleistocene, then the soil profile developed from this material is a heterochronous body with distinct features of polygenesis. If the parent material is a relatively homogeneous sediment that was not subjected to periglacial pedogenesis in the Late Pleistocene, then the soil profile developed from this material contains only the features of the Holocene pedogenesis, even in the case when the thickness of the homogeneous substrate does not exceed 0.5 m. It is hypothesized that the Holocene pedogenesis within the humid forest and southern taiga zones in the center of the Russian Plain cannot delete the features of the pre-Holocene pedogenesis and morpholithogenesis; these features are always inherited by the profiles of modern soils. The presence of these features ensures the development of a fully developed mature soil profile.     

江西九江地区第四纪红粘土上的“黄帽子”

A thin layer of yellow-brown-colored earth was generally found on Quaternary red clay in Jiujiang, Jiangxi Province. A typical profile was established. Both particle size distribution and REE (rare earth elements) characteristics of the yellow-brown-colored earth of the profile fully suggested its aeolian origin and close similarity to Nanjing Xiashu loess. The study also implied aeolian origin of the underlying Quaternary red clay. Compared with the red clay, the yellow-brown-colored earth was less weathered because of its lower content of free iron and higher mole ratios of SiO₂/Al₂O₃ and SiO₂/(Fe₂O₃+Al₂O₃) as well as its less developed chemical microtextures of quartz grains. In order to study the ages of the two deposits comparatively, the thermoluminescent dating method was used. As a result, the bottom of the yellow-brown-colored earth was dated to 60±5 ka B. P. and the upper part of the red clay 388±54 ka B. P. It was suggested that the yellow-brown-colored earth was formed in the Late Pleistocene and was probably the aeolian deposit of the Last Glacial, which corresponded with the Malan loess in the Loess Plateau of the northwestern part of China; while the underlying red clay was formed in the Middle Pleistocene. A "yellow cap" on Quaternary red clay in Jiujiang implied a great climatic and environmental variation in the beginning of the Late Pleistocene in the southern part of China, especially in the middle and lower reaches of the Yangtze River. The event not only halted the rubification, once dominating the region, but also produced a widespread covering of aeolian deposit, as only occurred in the cold and dry environment.     

Quartärgeomorphologische untersuchungen im Nordteil der “Tunesischen dorsale”

Seven Quaternary profiles from the Mediterranean region of northern Tunisia are described and their geomorphological significance assessed. Fifteen radiocarbon datings permit the field observations to be arranged in a chronosequence.The results indicate that the Late Pleistocene period witnessed the production and displacement of coarse debris, a process extending down to low altitudes. Until now, however, the only evidence for this has been found in the vicinity of steep slopes or rock walls. The coarse sediments partly overlie slope deposits derived from reddish soils; to some extent they contain fine reddish pedogenic material, and in part they are covered by it.In the Holocene, the displacement of fine alluvial sediments alternated several times with the formation of humic horizons. Anthropogenic influences on landscape evolution must be admitted as a possibility as from at least three thousand years ago.The aeolian sands of the Late Pleistocene and Middle Holocene are correlated with regressions of high sea levels.     

Clay-mineral indicators of glacial and nonglacial sources of Wisconsinan loesses in Southern Indiana,U.S.A.

Clay-mineral compositions of Peoria loess of later Wisconsinan age derived from Wabash Basin and Ohio Basin riverine sources differ in southern Indiana. In the Wabash province the composition is illite > expandable clay minerals > kaolinite and relates to the clay-mineral composition of glacial drift in the basin of 91% glacial cover. In the Ohio province the composition is expandable clay minerals > or ? illite > kaolinite and relates indirectly to the clay-mineral composition of the Sangamon Soil terrain on bedrock. Above the confluent Wabash Basin, 77% of the Ohio Basin is unglaciated. The clay-mineral composition of thin Farmdale loess of earlier Wisconsinan age also relates to the composition of the paleosol terrain. During Peorian time while glacial outwash was supplying loess source materials to the valleys in the Wabash Basin, ordinary alluvium derived from soils and bedrock in unglaciated terrain was supplying loess source materials to the valleys in the Ohio Basin.     

Mobile aluminum compounds in soils of the southern taiga (soils of the central forest reserve as an example)

The profile distributions of aluminum extracted by the Tamm and Bascomb reagents and of the exchangeable aluminum were studied in soils of automorphic, transitive, and accumulative positions in the landscapes of the southern taiga. In the mineral horizons of the gleyic peaty-podzolic soils developed on poorly drained flat surfaces and in the floodplain soils, the distribution of oxalate- and pyrophosphate-soluble aluminum has a strongly pronounced accumulative character. In the podzolic soils of the automorphic positions and slopes, an eluvial-illuvial distribution was characteristic with the maximal aluminum content in the podzolic horizons. The strong differentiation of the upper part of the profile in the automorphic podzolic soils in terms of the Al content in the Tamm and Bascomb extracts is mainly related to an increase of the pedogenic chlorite content upon the transition from the AE to the E horizon. In the podzolic horizons of these soils, aluminum can accumulate in the form of proto-imogolite structures. The exchangeable aluminum displays an accumulative type of distribution. On the basis of calculating the reserves of the different aluminum compounds, two main accumulative zones for the mobile compounds of this element were recorded in the soils of the landscapes studied: the E horizon in the automorphic podzolic soils, where Al accumulates as soil chlorite or, probably, as proto-imogolite, and the A1 horizon of the floodplain soils, where Al accumulates in aluminoorganic complexes.     

巫山黄土成因及其发育土壤特征研究

  目的  为探明巫山黄土成因,了解该类母质发育土壤的发生学特征。  方法  以典型巫山黄土及其发育土壤剖面为研究对象,通过野外调查采样和室内分析,详细考察剖面形态、颗粒组成、常量元素地球化学特征及其他相关理化性质,计算探讨硅铝率（ Sa ）、化学蚀变指数（ CIA ）、钠钾比（ Na/K ）、铁游离度等风化指标。  结果  （1）巫山黄土的颗粒组成以粉粒为主,平均含量为53.29%,与典型风尘沉积物相似,同时,巫山黄土与其他区域风成黄土的主要元素硅、铝、铁含量非常接近,上陆壳（UCC）标准化曲线也较为相似;（2）该剖面100 ~ 140 cm深度与其他深度相比,有机碳和硒含量较高,CaCO₃相当物含量和δ13C值较低,推测在此深度堆积过程中的气候较为温湿,并可能出现过植物的生长;（3）巫山黄土剖面的 Sa 为8.73 ~ 9.17、 CIA 为65.96 ~ 69.10、 Na/K 为0.74 ~ 0.89、铁游离度为22.88% ~ 29.74%,与其他地区风成黄土相比,巫山黄土风化程度强于洛川黄土而弱于下蜀黄土和成都黏土,与汉江黄土和甘孜黄土十分接近。  结论  巫山黄土应为风积成因,处于中等化学风化程度,以脱盐基为主,脱硅富铁铝化程度弱,可能与汉江黄土或甘孜黄土同源。     

Some specific features of the biochemical properties of soils

Soil can be perceived as a matric system with certain compartments. The mineral, organic, and organomineral matrices can be distinguished in it. The synthesis of humus in the soil is a continuous process with an abiotic final stage. The synthesis of polymers takes place on mineral and organomineral matrices. The development of humus horizon considerably reduces the migration of organic substances in the soil. Three different types of element associations can be distinguished in the soil: the geochemical association inherited from the parent material, the biochemical association inherited from the remains of living organisms entering the soil, and the biogeochemical (or proper pedogenic) association appearing in the course of interaction between the first two element associations under the given type of the soil water regime. The inhibitors and, probably, stimulators of plant growth also exist in the soil.     

古土壤地球化学的某些问题——黄土风化过程中元素的变化

对黄土中埋藏古土壤的研究有过许多报道^[2,5,8].但对黄土风化过程中元素的变化讨论则不多.笔者是在近年来对陕西洛川黄土剖面工作的基础上,讨论了不同类型古土壤中元素的含量与分布,古土壤剖面中元素的变化.并将古土壤的化学组成与黄土母质进行比较,进而论述了在古气候变迁的影响下,黄土剖面中元素迁移、积聚的地球化学特征.这对探讨黄土的堆积环境和生物气候条件的演变,以及地层划分等均有十分重要意义.     

环洞庭湖区两种典型红土理化特性比较研究

通过环洞庭湖区两种典型成因红土的野外勘察与取样、室内磁化率、粒度、微量元素(Li、Rb、Sr、Ba)分析,进行两种不同成因的红土理化性质的比较。研究结果表明,风成成因的红土粒度比基岩风化成因红土明显较细,风成成因红土以粉砂为主,基岩风化型红土为砂和粉砂为主;两种成因红土受到长江中游地区高温高湿的气候条件影响,磁化率均显示为低值,明显低于黄土高原黄土和长江下游下蜀黄土;微量元素Li/Ba、Rb/Sr比值显示为高值,显著高于黄土高原黄土和长江中下游地区下蜀黄土,表明两种红土均经历了强烈的风化淋溶过程,但基岩风化型红土的风化成壤强于风成成因红土,可能基岩风化型红土经历了更长的风化成壤过程。     

CHARACTERISTICS OF NUBIAN SANDSTONE-DERIVED SOILS

Nubian sandstone exposures in sub-humid, semi-arid, and arid environments have given rise to red, sandy but in other respects very different soils. Soils have a fairly well developed profile only in the sub-humid zone, including a textural B horizon and are free of soluble salts and carbonates. In the semi-arid and arid zones, profile differentiation is weak or non-existent. Soils are shallow and contain carbonates, and in the arid zone also soluble salts, including gypsum. Kaolinite is the only clay mineral which is common to all the nubian sandstone parent materials. It is the major clay mineral in the sub-humid zone soil. In the semi-arid soils smectite is a second major clay component. In the arid zone both smectite and palygorskite, in minor amounts, accompany kaolinite. Both smectite and palygorskite are probably pedogenic neoformation products. Material of aeolian origin has probably been introduced into the silt and fine sand fractions of both the semi-arid and arid soils. Some contamination of the clay fractions may have also occurred.