ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2005-2009  (89)
Collection
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The marshlands of western France provide the opportunity to relate the magnetic properties of a recent sedimentary clay soil to pedogenesis, including the impact of agriculture and drainage on magnetic mineralogy. We studied a plot of drained land that had been ploughed up to 1998 and under grass since. A new thermomagnetic method was used to identify and to quantify roughly the magnetic minerals, which represent less than 1 g kg−1. The most abundant Fe oxides are haematite (45%) and goethite (45%). However, trace amounts of the ferrimagnetic minerals maghemite (4%), magnetite (3%) and, to a lesser extent, iron sulphides (1%) provide most of the magnetic signal. This signal allowed us to identify magnetic horizons that relate to the soil horizons. The topsoil is characterized by a strong magnetic enhancement (4-fold), and the thickness of this layer increases close to the drains. Relative contents of ferrimagnetic phase also increase laterally with decreasing distance to the drains. Magnetic enhancement coincides with the most aerated and developed layer, in which water circulation, root colonization and hence soil fertility are greater. Ferromagnetic minerals sensu lato, especially maghemite and magnetite, can be considered as mineralogical tracers partly and indirectly reflecting soil fertility of these clay-rich marshland soils.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This paper describes a wavelet transform for the analysis of categorical (multistate) soil variables, i.e. ones (such as profile classes) that have two or more discrete states. The states are transformed to a continuous variable by a mapping which is optimized by scale and location to highlight local variation.The method is illustrated with data from a transect across a gilgai landscape in Australia. A categorical variable on relief, with three states, was recorded from the sample sites, from which soil cores had also been collected and analysed. The wavelet analysis showed a transient feature of the variation at scales up to 32 m. There was an interval where the characteristic alternation of depressions with the level plain was interrupted. The variation at scale 64 m appeared to be non-stationary. The relief was more variable on one side of a change point than it was on the other.This complex variation of relief was matched by that of the electrical conductivity of the soil, most strongly at the 64-m scale. The periodicity of conductivity, and the strength of its correlation with relief, were also different either side of the change point identified in the analysis of relief alone. Conductivity also showed similar transient features to relief.Evidently the wavelet transform can be used to elucidate the variation of categorical soil variables. The information from such an analysis is likely to be useful for planning surveys of the soil to measure continuous variables by sampling and laboratory analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Risk assessment of groundwater pollution requires quantitative information on the release kinetics of pollutants and organic matter from contaminated soil. We applied a new experimental design for column outflow experiments to investigate the release of polycyclic aromatic hydrocarbons (PAHs) and dissolved organic matter under water-saturated flow conditions. We used materials originating from a soil contaminated with non-aqueous phase liquids. To distinguish between release at equilibrium and release limited by mass transfer, we used two flow velocities and multiple interruptions to the flow. We quantified release and transport parameters by inverse numerical simulation of the individual breakthrough curves, applying a model based on the advection–dispersion equation including non-equilibrium and non-linear sorption. Release of the dissolved organic C takes place in two steps. Initially, a large amount of readily available organic matter is released. This first flush is followed by an outflow with typical characteristics of rate-limited release: larger concentrations in slower flow and increased concentrations after interruptions. The breakthrough of PAHs responds neither to the different flow velocities nor to the interruptions. We hypothesize that release of PAHs from the contaminated material is governed by dissolution at equilibrium according to Raoult's law. The boundary conditions of the experimental design, i.e. the flow velocities and multiple interruptions, enable us to distinguish between release at equilibrium and that which is rate-limited. Also, the response of the breakthrough behaviour to the boundary conditions can be used to estimate inversely effective release parameters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of freezing on soil phosphorus (P) chemistry are poorly understood, although freezing is habitual for many soils at middle and high latitudes. We studied the effects of various freezing treatments on the solubility and sorption of P in an incubation experiment on two coarse and two fine-textured cultivated surface soils in Finland. Air-drying was included in the experimental arrangement because freezing and drying have similar features. Compared with field-moist soils stored at +5°C in the dark, freezing had few effects on P extractability by water or on sorption properties of P studied with a Q/I plot technique. Air-drying, by contrast, increased almost systematically the equilibrium concentration of P estimated with Q/I plots, water-soluble organic carbon, and the extractability of P, aluminium, iron and manganese in the soils. The results imply that drying destroys organomineral complexes. The breakdown of these complexes releases P, while simultaneously exposing new surfaces on which P could sorb. Because of the considerable impact of drying on the behaviour of P, air-drying of soil samples should be avoided in studies of the chemistry of P in soil. Freezing seems to be a safe way of storing mineral soil for such studies, but it may significantly alter the P conditions of soils rich in organic matter.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: We measured sorption of selenite and phosphate, both separately and in competition, in a Chilean Andisol. We also used previously published data for competitive sorption of arsenate and phosphate by a clay subsoil. We wrote computer programs that allowed us to compare the fits of differing versions of equations to describe individual sorption and competitive sorption. For the selenite–phosphate data, the index term of the Freundlich equation decreased as concentration increased. This was described using the Sibbesen modification of the Freundlich equation. This modification was then included in competition equations. For both the selenite–phosphate and the arsenate–phosphate data, competition was not ‘symmetrical’, that is, the competition terms were not reciprocals of each other. We think this occurred because competition between ions is not only competition for adsorption sites but also involves electrical effects that follow penetration of the surface.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: We undertook what we believe to be a unique survey of the natural abundances of 13C and 15N in urban soils and plants in Karlsruhe (Germany), a European city of average size. We found broad patterns of these abundances in both soils and plants, which reflected geology and land use. In contrast with studies on smaller areas (showing the direct effect of human activities), our study first determined the extent to which the abundances correlated with land use or underlying geology and then assessed how we could further test such relationships. The spatial pattern of δ13C in surface soil correlated with that of the underlying parent material; construction activities superimposed a secondary signal. Maize cultivation was a source of less negative soil δ13C, whereas the C3 vegetation is a source of more negative soil δ13C. There was a footprint of less negative plant δ13C in the industrial and port areas; plant δ13C downwind of the city was less negative than upwind, which might relate to atmospheric pollution from the port area or to differences in soil properties. There was no significant effect of wind direction or geology on soil or plant δ15N, which was correlated mainly with land use. The largest soil δ15N was under agriculture and the smallest under woodland. The abundance of 15N in inner-urban soil and plants was intermediate between those of agriculture and forests. This study represents a major advance in the use of stable isotope geochemistry in understanding urban environments.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Soil pore networks have a complex geometry, which is challenging to model in three dimensions. We use a Boolean model of pore space that has proved useful in modelling gas diffusion in dry structures to investigate the distribution of water in this pore space and to quantify the effects on pore connectivity to the soil surface. We first show how total porosity in dry soil influences connectivity via the percolation threshold. Then we show that our model simulation of the ‘ink-bottle effect’ can account for much of the hysteresis of the soil water. The differences in distribution of water between wetting and drying result in maintaining greater connectivity of the air-filled pore space during drying than during wetting. Hysteresis is large at small total porosities and slowly declines as porosity increases. During wetting much pore space is blocked when more than 40% of the pore space is filled with water, although during drying all non-isolated air-filled pores are connected to the surface. Even when soil is allowed to wet to near saturation, there are rapid increases in pore connectivity during drying, which may explain, for example, rapid increases in production and emission of nitrous oxide in soils near saturation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Water movement in soil can be described accurately at the local scale, provided that soil hydraulic properties can be determined with precision. Traditional methods for characterizing soil are often time consuming, and large areas cannot be sampled easily. We present a simple method for overcoming these difficulties. It is easy to implement and cheap. It is known as the Beerkan method, and it relies on particle-size analysis, dry bulk density and simple infiltration tests in cylinders. We describe the experimental protocol and the method of data analysis, leading to the estimation of parameters describing hydraulic properties. Shape parameters depend on soil texture and are derived from particle-size data. Normalization parameters depend on soil structure. They are derived by inverse modelling and optimization from the infiltration tests. The theoretical background relies on the sorptivity concept and scaled forms of the infiltration equation. The formalism for one- and three-dimensional analysis is described. We assess the accuracy of the method using published data and simulated values, showing the soundness of the approach. For the purpose of illustration, we implemented a simple optimization technique on two bounding cases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The inability of physical and chemical techniques to separate soil organic matter into fractions that have distinct turnover rates has hampered our understanding of carbon (C) and nutrient dynamics in soil. A series of soil organic matter fractionation techniques (chemical and physical) were evaluated for their ability to distinguish a potentially labile C pool, that is ‘recent’ root and root-derived soil C. ‘Recent’ root and root-derived C was operationally defined as root and soil C labelled by 14CO2 pulse labelling of rye grass–clover pasture growing on undisturbed cores of soil. Most (50–94%) of total soil + root 14C activity was recovered in roots.Sequential extraction of the soil + roots with resin, 0.1 m NaOH and 1 m NaOH allocated ‘recent’ soil + root 14C to all fractions including the alkali-insoluble residual fraction. Approximately 50% was measured in the alkali-insoluble residue but specific activity was greater in the resin and 1 m NaOH fractions. Hot 0.5 m H2SO4 hydrolysed 80% of the 14C in the alkali-insoluble residue of soil + roots but this diminished specific activity by recovering much non-14C organic matter. Pre-alkali extraction treatment with 30% H2O2 and post-alkali treatment extractions with hot 1 m HNO3 removed organic matter with a large 14C specific activity from the alkali-insoluble residue.Density separation failed to isolate a significant pool of ‘recent’ root-derived 14C. The density separation of 14C-labelled roots, and roots remixed with non-radioactive soil, showed that the adhesion of soil particles to young 14C-labelled roots was the likely cause of the greater proportion of 14C in the heavy fraction.Simple chemical or density fractionations of C appear unsuitable for characterizing ‘recent’ root-derived C into fractions that can be designated labile C (short turnover time).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The value of nested sampling for exploring the spatial structure of univariate variation of the soil has been demonstrated in several studies and applied to practical problems. This paper shows how the method can be extended to the multivariate case. While the extension is simple in theory, in practice the direct estimation of covariance components by equating mean-square matrices with their expectation will often lead to estimates that are not positive semidefinite. This paper discusses solutions to this problem for balanced and unbalanced sample designs. In the balanced case there is a residual maximum likelihood (REML) estimator that will find estimates of covariance components that maximize an overall likelihood on the condition that all components are positive semidefinite (p.s.d.). This is possible because the condition is met if the differences of successive mean-square matrices are positive semidefinite, and this constraint can be incorporated into an algorithm. This does not hold for unbalanced designs. In this paper the problem was solved for unbalanced designs by scaling covariance components that were not p.s.d. to the nearest p.s.d. matrix according to a Euclidean distance.These methods were applied to data from three surveys, two with balanced and one with unbalanced sampling. Different patterns of scale-dependence of the correlation of soil properties were found. For example, at Ginninderra Experimental Station in Australia the soil water content and bulk density were correlated significantly, with the correlation increasing with distance to 56 m, but at longer distances the properties were not significantly correlated. By contrast, the pH of the soil and the available P content showed correlation that increased with distance. The implications of these results for planning more detailed sampling, both for prediction and for investigation of processes, are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...