The subdivision of a slope profile on the basis of soil properties: A case study from mid-wales     

Donald A. Davidson 《地球表面变化过程与地形》1977,2(1):55-61

Sedimentological analysis of particle size data from a hillslope profile in mid-Wales allows the identification of two distinct upper slope units. These are described and analyzed in greater detail for clay and organic matter distribution. The original slope subdivision is substantiated by the results and the major differences in soils between the upper units are attributed to drainage contrasts.  相似文献   

Watershed geochemistry: The control of aqueous solutions by soil materials in a small watershed     

Terence R. Smith  Thomas Dunne 《地球表面变化过程与地形》1977,2(4):421-425

Laboratory and field data indicate that the aqueous geochemistry of a small watershed in siliceous materials is largely determined by reactions between soil and water. For dissolved SiO₂, Ca⁺², K⁺, Na⁺, a reversible steady state is achieved in the soil within hours. The solute concentrations are in equilibrium with kaolinite, the end-product in the local weathering sequence. The processes occur in a drainage basin in which solution activities are the predominant form of erosion.  相似文献   

Determination of organic carbon in soils and sediments in an automatic method   总被引：1，自引：0，他引：1       下载免费PDF全文

LI Guo-ao  YAN Lei  CHEN Zhen-he  LI Ye 《地下水科学与工程》2017,5(2):124-129

Our automatic digestion device is applied in determining the quantity of organic carbon in the soils/sediments. Its operation process is simple. The reaction conditions are optimized; the complex pretreatments are automated; and a great number of samples can be analyzed at the same time. Comparison shows that the experiment using the device is safer and easier. The correlation coefficiency is greater than 0.999, indicating a good linear relationship. The relative standard deviations of three different concentrations are less than 5%. Standard addition recoveries of high and low concentration range between 94.7% and 100% and between 91.7% and 105% respectively. Method determination limitation (MDL) of this method meets the practical requirements. The device in this paper supports a compositive SOC determination method. Its advantages include improved time and labor efficiency, and accuracy. The device is widely used in the studies of agricultural science, carbon cycle, climate change and environmental protection.  相似文献   

Lithogenic concentrations of trace metals in soils and saprolites over crystalline basement rocks: A case study from SW Nigeria   总被引：2，自引：0，他引：2  

Moshood N. Tijani  Olugbenga A. Okunlola  Akinlolu F. Abimbola 《Journal of African Earth Sciences》2006,46(5):427-438

In this study, an assessment of the lithogenic concentrations of trace metals in soils and saprolite over basement rock units in Ibadan, SW-Nigeria is presented in respect of bedrock types and geochemical controls on the weathering-associated release of trace metals. Consequently, soil, weathered and fresh rock samples from the Precambrian Basement of SW Nigeria were collected from three different bedrock units within Ibadan metropolis and subjected to mineralogical and geochemical analyses. The analytical results revealed major proportions of oxides in the range of 18–20% Al₂O₃, 2–6% Na₂O and 1–6% K₂O for weathered profiles over granite-gneiss and pegmatite units, compared to 2–3% Al₂O₃, <0.5% Na₂O and <1.0% K₂O over schist-quartzite. For the trace elements, weathered profiles on granite-gneiss and schist-quartzite settings exhibit similar enrichment trends (enrichment factor, EF l) for most of the trace elements, unlike the pegmatite bedrock. However, enrichments are relatively greater in the top soil unit compared to the intermediate saprolite unit, especially for Pb, Ni, Zn, Cr, Co, Rb, Sr and Ba, a situation attributed to leaching and redistribution within the weathered profiles through pedogenetic process and percolating groundwater.Furthermore, the estimated weathering indices using Ruxton Ratio (RR = {SiO₂/Al₂O₃}) and Chemical Index of Alteration (CIA = 100{Al₂O₃/[Al₂O₃ + CaO + Na₂O + K₂O]}) revealed RR of 2.9–3.7 and CIA of 54–73% for granite-gneiss and pegmatite units, implying medium levels of weathering, compared to RR of 30.8–35.5 and CIA of >60% for schist-quartzite units, which suggest weak chemical weathering. Also, the estimated high percentage loss, especially for Pb, Rb, Sr, Ba relative to the bedrocks, shows that the trace elements can be mobilized within the weathering profiles even at a low degree of chemical weathering. Such weathering-induced release of trace metals is of environmental significance as natural lithogenic input sources and as background reference for future monitoring of possible human/anthropogenic impacts.  相似文献   

土壤坑蚀性实验研究     

吴淑安  蔡强国 《云南地理环境研究》1996,8(1):73-80

对采自内蒙东胜、河北张家口、山西离石和湖北通城、秭归等不同自然地理环境区的９２个土壤样，分别进行了其各项物理、化学特性的测定，和崩解、溅蚀、贯入试验，发现不同土类的试验结果与其理化性状之间存在规律性，它们是土壤抗蚀性的反映。文中还对不同土壤的抗蚀性大小进行了讨论。  相似文献   

LOCATION OF SERVICE ACTIVITIES IN DENMARK     

SVEN ILLERIS M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):58-64

Sven Illeris: Location of Service Activities in Denmark, with Special Regard to Rural Areas. Geografisk Tidsskrift 75: 58–64. København, juni 1, 1976.

The paper describes the purposes and methods of a study of the present and future location of service activities. Some of the most important findings are dealt with, e.g. estimates and plans for the 1988 distribution of service between size-classes of towns.  相似文献   

Distribution of heavy metals in urban soils – a case study of Danang-Hoian Area (Vietnam)     

H. T. T. Thuy  H. J. Tobschall  P. V. An 《Environmental Geology》2000,39(6):603-610

 This work is part of a research study which is intended to study the degree of anthropogenic influences of the trace metal distribution of soils from Danang-Hoian area (Vietnam). Cu, Ni, Zn and Zr show significant effects in most of the cultivated soil categories, especially in the industrial soils. Extremely high levels of Pb (up to 742 μg/g) are observed in the industrial soil category, which shows an enrichment factor 114 as compared to rural soils. Cd shows only a relative local enrichment with the maximum level of 4.6 μg/g in urban soils. Sequential extraction was performed in selected samples to evaluate the geochemical trace metals. The result indicates that Zn and Cr are mainly found in the crystal and amorphous Fe oxide bounded forms. The contents of Cr in these fractions comprise more than 94% of total extractable Cr. In the case of Zn, 85% of total extractable Zn is in fractions F_V and F_VI. Cu is mainly found in the organic fraction at an average of 39.3% of total extractable content. On the other hand, heavy metal contents show an increasing tendency in the fine fraction (silt and clay). Received: 4 February 1998 · Accepted: 26 November 1998  相似文献   

南京地区土体热导率性质测试与分析   总被引：3，自引：1，他引：2  

苏天明  晏长根  俞缙  王玉英 《工程地质学报》2006,14(2):212-215

通过对南京地区大量粘土和粉质粘土样品热导率值的测试,分析了土体热导率与其含水量、孔隙比的相关关系。对影响土体导热值的因素作了详细分析,提出了根据土体含水量、孔隙比值计算土体热导率的经验计算公式。  相似文献   

Genesis of marine terrace soils,Barbados, West Indies: Evidence from mineralogy and geochemistry     

Daniel R. Muhs  Russell C. Crittenden  John N. Rosholt  Charles A. Bush  Kathleen C. Stewart 《地球表面变化过程与地形》1987,12(6):605-618

Well-developed, clay-rich soils dominated by interstratified kaolinite-smectite are found on the uplifted coral reef terraces on the island of Barbados. The reef limestone is unlikely to have been the soil parent material however, because it is 98 per cent CaCO₃ and geomorphic evidence argues against the 20 m of reef solution required to produce the soils by this process. The mineralogy of the sand, silt, and clay fractions of the soils, and trace element geochemistry, suggest that aeolian materials carried on the trade winds from Africa, volcanic ash from the island of St. Vincent, and quartz from Tertiary bedrock on the island itself are the parent materials for the soils.  相似文献   

An improved search strategy for the critical slip surface using finite element stress fields   总被引：17，自引：0，他引：17  

J.Y Kim  S.R Lee 《Computers and Geotechnics》1997,21(4):950-313

The finite element method can be used to advantage in slope stability problems. This paper proposes a technique to search for the critical slip surface as well as to define and calculate the factor of safety for the slope, when the finite element method is used to model its formation. First, stresses are estimated at each Gaussian point from the finite element analysis. Then, the global stress smoothing method is applied to get a continuous stress field. Based on this stress field, the factor of safety is calculated for a specified slip surface by a stress integration scheme. An improved search strategy is proposed for a noncircular critical surface which starts with a search method for a circular critical surface. During the search process, points defining a trial slip surface can freely move in the finite element mesh subject to some kinematical constraints. This method can be applied to both the limit equilibrium method and the finite element method. Effects of the slope stress history and soil parameters on the resulting critical surface are investigated.  相似文献