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Parent Material (parent + material)
Kinds of Parent Material Selected AbstractsNutrient Dynamics of Soil Derived from Different Parent Material on Barro Colorado Island, Panama,BIOTROPICA, Issue 2 2000Joseph B. Yavitt ABSTRACT I compared the concentrations of N, P, and S in both litter and mineral soil (0,15 cm depth) from three old-growth, tropical moist forests on Barro Colorado Island (BCI), Panama. Each site was on a different substrate (i.e., parent material), but otherwise had similar climate, vegetation, and topography. There were no site differences in concentrations of N and S for either litter or soil. Concentrations of litter P and soil-extractable P were greater for the andesite (igneous rock) site than for two sites on different sedimentary rocks; however, concentrations of several other litter and soil P fractions did not differ among sites. Patterns in soil P fractions suggested advanced soil development to the point that parent material has little control of P dynamics. Litter samples from each site, leached in the laboratory, released similar amounts of N, P, and S to the soil, indicating no differences in rates of turnover in the litter and in fluxes from litter into the mineral soil among sites. I expected more site differences in soil nutrient dynamics given vastly different parent materials and soil types (i.e., Oxisol vs. Alfisol) and very shallow soil on BCI that brings the parent material close to the plant root zone. Erosion and soil mixing may explain the uniformity in soil nutrient dynamics across the sites. [source] Ambipolar Organic Field-Effect Transistors from Cross-Conjugated Aromatic Quaterthiophenes; Comparisons with Quinoidal Parent MaterialsADVANCED FUNCTIONAL MATERIALS, Issue 3 2009Rocío Ponce Ortiz Abstract This contribution presents an electrochemical, Raman spectroscopic, and theoretical study probing the differences in molecular and electronic structure of two quinoidal oligothiophenes (3,,4,-dibutyl-5,5,-bis(dicyanomethylene)-5,5,-dihydro-2,2,:5,,2,-terthiophene and 5,5,-bis(dicyanomethylene)-3-hexyl-2,5-dihydro-4,4,-dihexyl-2,2,,5,5,-tetrahydro-tetrathiophene) with terminal tetracyanomethylene functionalization and aromatic oligothiophenes where acceptor moieties are positioned at lateral positions along the conjugated chain (6,6,-dibutylsulfanyl-[2,2,-bi-[4-dicyanovinylene-4H-cyclopenta[2,1-b:3,4-b,]dithiophene]). In this way, the consequences of linear and cross conjugation are compared and contrasted. From this analysis, it is apparent that organic field-effect transistors fabricated with cross-conjugated tetrathiophene semiconductors should combine the benefits of an electron-donor aromatic chain with strongly electron-accepting tetracyanomethylene substituents. The corresponding organic field-effect transistors exhibit ambipolar transport with rather similar hole and electron mobilities. Moreover, n-channel conduction is enhanced to yield one of the highest electron mobilities found to date for this type of material. [source] Vegetation and topographic controls on sediment deposition and storage on gully beds in a degraded mountain areaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2009Armando Molina Abstract Active gully systems developed on highly weathered or loose parent material are an important source of runoff and sediment production in degraded areas. However, a decrease of land pressure may lead to a return of a partial vegetation cover, whereby gully beds are preferred recolonization spots. Although the current knowledge on the role of vegetation on reducing sediment production on slopes is well developed, few studies exist on the significance of restoring sediment transport pathways on the total sediment budget of degraded mountainous catchments. This study in the Ecuadorian Andes evaluates the potential of vegetation to stabilize active gully systems by trapping and retaining eroded sediment in the gully bed, and analyses the significance of vegetation restoration in the gully bed in reducing sediment export from degraded catchments. Field measurements on 138 gully segments located in 13 ephemeral steep gullies with different ground vegetation cover indicate that gully bed vegetation is the most important factor in promoting short-term (1,15 years) sediment deposition and gully stabilization. In well-vegetated gully systems ( , 30% of ground vegetation cover), 0.035 m3 m,1 of sediment is deposited yearly in the gully bed. Almost 50 per cent of the observed variance in sediment deposition volumes can be explained by the mean ground vegetation cover of the gully bed. The presence of vegetation in gully beds gives rise to the formation of vegetated buffer zones, which enhance short-term sediment trapping even in active gully systems in mountainous environments. Vegetation buffer zones are shown to modify the connectivity of sediment fluxes, as they reduce the transport efficiency of gully systems. First calculations on data on sediment deposition patterns in our study area show that gully bed deposition in response to gully bed revegetation can represent more than 25 per cent of the volume of sediment generated within the catchment. Our findings indicate that relatively small changes in landscape connectivity have the potential to create strong (positive) feedback loops between erosion and vegetation dynamics. Copyright © 2009 John Wiley & Sons, Ltd. [source] The influence of parent material on topsoil geochemistry in eastern EnglandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2003B. G. Rawlins Abstract The topsoil of around 10 000 km2 in eastern England has recently been sampled intensely at 4609 sites to characterize its geochemistry. The parent materials, which include both solid geology and Quaternary sediments, range in age from Permian to Holocene. The distributions of the concentrations of major and trace elements have been characterized geostatistically, and the role of parent material on their spatial structure (anisotropy) and their spatial relationships (coregionalization) have been investigated. Analysis of variance with the sites grouped by major parent material type showed that this classi,cation accounted for 14 to 48 per cent of the variance for the various elements. Global variograms of 13 elements (Al, As, Ca, Cr, Cu, Fe, Mg, Mo, Ni, P, Pb, Ti, and U) have been computed and modelled. Eleven of the variograms seem to comprise two structures, both of which we modelled with spherical functions, one of short range, 3·5 to 9 km, and the other with a range of 15 to 23 km. The models included a nugget variance, which varied from 27 per cent (for As, Fe, and Mg) to 63 per cent (for P) of the total. The long-range structures are related to the separations of the major parent materials. The variograms of several elements showed appreciable anisotropy, most notably that of Mg. Anisotropy is evident at short ranges of less than 5 km. This accords with the geological structure of the beds which dip from west to east so that their outcrops are elongated from north to south. A linear model of coregionalization ,tted to the data emphasized several important geochemical associations, which we interpret. Elements commonly associated with clay minerals (Mg, Al) and the clay size fraction (Ti) are dominated by the long-range structure of the coregionalization, whilst several trace elements (As, Cr, Ni and U) are spatially correlated with Fe over short distances, through adsorption of the former on the surfaces of Fe oxyhydroxides. The topsoil around large urban areas is enriched in lead, but it is not clear whether anthropogenic sources are responsible for this metal's anomalous spatial relationships with other elements. Crown copyright © 2003. Reproduced with the permission of Her Majesty's Stationery Of,ce. Published by John Wiley & Sons, Ltd. [source] Sampling and analytical plus subsampling variance components for five soil indicators observed at regional scaleEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 5 2009B. G. Rawlins Summary When comparing soil baseline measurements with resampled values there are four main sources of error. These are: i) location (errors in relocating the sample site), ii) sampling errors (representing the site with a sample of material) iii) subsampling error (selecting material for analysis) and iv) analytical error (error in laboratory measurements). In general we cannot separate the subsampling and analytical sources of error (since we always analyse a different subsample of a specimen), so in this paper we combine these two sources into subsampling plus analytical error. More information is required on the relative magnitudes of location and sampling errors for the design of effective resampling strategies to monitor changes in soil indicators. Recently completed soil surveys of the UK with widely differing soils included a duplicate site and subsampling protocol to quantify ii), and the sum of iii) and iv) above. Sampling variances are estimated from measurements on duplicate samples , two samples collected on a support of side length 20 m separated by a short distance (21 m). Analytical and subsampling variances are estimated from analyses of two subsamples from each duplicate site. After accounting for variation caused by region, parent material class and land use, we undertook a nested analysis of data from 196 duplicate sites across three regions to estimate the relative magnitude of medium-scale (between sites), sampling and subsampling plus analytical variance components, for five topsoil indicators: total metal concentrations of copper (Cu), nickel (Ni) and zinc (Zn), soil pH and soil organic carbon (SOC) content. The variance components for each indicator diminish by about an order of magnitude from medium-scale, to sampling, to analytical plus subsampling. Each of the three fixed effects (parent material, land use and region) were statistically significant for each of the five indicators. The most effective way to minimise the overall uncertainty of our observations at sample sites is to reduce the sampling variance. [source] Spatial variation of ammonia volatilization from soil and its scale-dependent correlation with soil propertiesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2008R. Corstanje Summary Quantitative predictions of ammonia volatilization from soil are useful to environmental managers and policy makers and empirical models have been used with some success. Spatial analysis of the soil properties and their relationship to the ammonia volatilization process is important as predictions will be required at disparate scales from the field to the catchment and beyond. These relationships are known to change across scales and this may affect the performance of an empirical model. This study is concerned with the variation of ammonia volatilization and some controlling soil properties: bulk density, volumetric water content, pH, CEC, soil pH buffer power, and urease activity, over distances of 2, 50, 500, and >2000 m. We sampled a 16 km × 16 km region in eastern England and analyzed the results by a nested analysis of (co)variance, from which variance components and correlations for each scale were obtained. The overall correlations between ammonia volatilization and the soil properties were generally weak: ,0.09 for bulk density, 0.04 for volumetric water content, ,0.22 for CEC, ,0.08 for urease activity, ,0.22 for pH and 0.18 for the soil pH buffer power. Variation in ammonia volatilization was scale-dependent, with substantial variance components at the 2- and 500-m scales. The results from the analysis of covariance show that the relationships between ammonia volatilization and soil properties are complex. At the >2000 m scale, ammonia volatilization was strongly correlated with pH (,0.82) and CEC (,0.55), which is probably the result of differences in parent material. We also observed weaker correlations at the 500-m scale with bulk density (,0.61), volumetric water content (0.48), urease activity (,0.42), pH (,0.55) and soil pH buffer power (0.38). Nested analysis showed that overall correlations may mask relationships at scales of interest and the effect of soil variables on these soil processes is scale-dependent. [source] Soil organic carbon in density fractions of tropical soils under forest , pasture , secondary forest land use changesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008S. Paul Summary Our knowledge of effects of land use changes and soil types on the storage and stability of different soil organic carbon (SOC) fractions in the tropics is limited. We analysed the effect of land use (natural forest, pasture, secondary forest) on SOC storage (depth 0,0.1 m) in density fractions of soils developed on marine Tertiary sediments and on volcanic ashes in the humid tropics of northwest Ecuador. The origin of organic carbon stored in free light (< 1.6 g cm,3) fractions, and in two light fractions (LF) occluded within aggregates of different stability, was determined by means of ,13C natural abundance. Light occluded organic matter was isolated in a first step after aggregate disruption by shaking aggregates with glass pearls (occluded I LF) and in a subsequent step by manual destruction of the most stable microaggregates that survived the first step (occluded II LF). SOC storage in LFs was greater in volcanic ash soils (7.6 ± 0.6 Mg C ha,1) than in sedimentary soils (4.3 ± 0.3 Mg C ha,1). The contribution of the LFs to SOC storage was greater in natural forest (19.2 ± 1.2%) and secondary forest (16.6 ± 1.0%) than in pasture soils (12.8 ± 1.0%), independent of soil parent material. The amount of SOC stored in the occluded I LF material increased with increasing silt + clay content (sedimentary soils, r = 0.73; volcanic ash soils, r = 0.58) and aggregation (sedimentary soils, r = 0.52; volcanic ash soils, r = 0.45). SOC associated with occluded I LF, had the smallest proportion of new, pasture-derived carbon, indicating the stabilizing effect of aggregation. Fast turnover of the occluded II LF material, which was separated from highly stable microaggregates, strongly suggested that this fraction is important in the initial process of aggregate formation. No pasture-derived carbon could be detected in any density fractions of volcanic ash soils under secondary forest, indicating fast turnover of these fractions in tropical volcanic ash soils. [source] Distribution of microbial biomass and phospholipid fatty acids in Podzol profiles under coniferous forestEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2000H. Fritze Summary Microbial-derived phospholipid fatty acids (PLFAs) can be used to characterize the microbial communities in soil without the need to isolate individual fungi and bacteria. They have been used to assess microbial communities of humus layers under coniferous forest, but nothing is known of their distribution in the deeper soil. To investigate the vertical distribution we sampled nine Podzol profiles on a 100-m-long transect in a coniferous forest and analysed for their microbial biomass and PLFA pattern to a depth of 0.4 m. The transect covered a fertility gradient from Vaccinium vitis-idaea forest site type to Vaccinium myrtillus forest site type. The cores were divided into humus (O) and eluvial (E) layers and below that into 10-cm sections and designated as either illuvial (B) or parent material (C), or as a combination (BC). Two measures of microbial biomass analyses were applied: substrate-induced respiration (SIR) to determine microbial biomass C (Cmic), and the sum of the extracted microbial-derived phospholipid fatty acids (totPLFA). The soil fertility had no effect on the results. The Cmic correlated well with totPLFA (r=,0.86). The microbial biomass decreased with increasing depth. In addition the PLFA pattern changed with increased depth as assessed with principal component analysis, indicating a change in the microbial community structure. The composition of the PLFAs in the O layer differed from that in the E layer and both differed from the upper part of the B layer and from the rest of the BC layers. The deeper parts of the B layer (BC1, BC2 and BC3) were similar to one other. The O layer had more 18:2,6, a PLFA indicator of fungi, whereas the E layer contained relatively more of the PLFAs 16:1,9, 18:1,7 and cy19:0 common in gram-negative bacteria. With increased depth the relative amount of 10Me18:0, the PLFA indicator for actinomycetes, increased. We conclude that the PLFA method is a promising discriminator between the microbial community structures of the horizons in Podzols. [source] Fatigue behaviour of friction stir welded AA2024-T3 alloy: longitudinal and transverse crack growthFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 7 2008M. T. MILAN ABSTRACT The fatigue crack growth properties of friction stir welded joints of 2024-T3 aluminium alloy have been studied under constant load amplitude (increasing -,K), with special emphasis on the residual stress (inverse weight function) effects on longitudinal and transverse crack growth rate predictions (Glinka's method). In general, welded joints were more resistant to longitudinally growing fatigue cracks than the parent material at threshold ,K values, when beneficial thermal residual stresses decelerated crack growth rate, while the opposite behaviour was observed next to KC instability, basically due to monotonic fracture modes intercepting fatigue crack growth in weld microstructures. As a result, fatigue crack growth rate (FCGR) predictions were conservative at lower propagation rates and non-conservative for faster cracks. Regarding transverse cracks, intense compressive residual stresses rendered welded plates more fatigue resistant than neat parent plate. However, once the crack tip entered the more brittle weld region substantial acceleration of FCGR occurred due to operative monotonic tensile modes of fracture, leading to non-conservative crack growth rate predictions next to KC instability. At threshold ,K values non-conservative predictions values resulted from residual stress relaxation. Improvements on predicted FCGR values were strongly dependent on how the progressive plastic relaxation of the residual stress field was considered. [source] Soil parent material is a key determinant of the bacterial community structure in arable soilsFEMS MICROBIOLOGY ECOLOGY, Issue 3 2006Andreas Ulrich Abstract The bacterial community composition in soil and rhizosphere taken from arable field sites, differing in soil parent material and soil texture, was analyzed using terminal restriction fragment length polymorphism (T-RFLP) of 16S rRNA genes. Nine sandy to silty soils from North-East Germany could clearly be distinguished from each other, with a relatively low heterogeneity in the community structure within the field replicates. There was a relationship between the soil parent material, i.e. different glacial and aeolian sediments, and the clustering of the profiles from different sites. A site-specific grouping of T-RFLP profiles was also found for the rhizosphere samples of the same field sites that were planted with potatoes. The branching of the rhizosphere profiles corresponded partly with the soil parent material, whereas the effect of the plant genotype was negligible. Selected terminal restriction fragments differing in their relative abundance within the nine soils were analyzed based on the cloning of the 16S rRNA genes of one soil sample. A high phylogenetic diversity observed to include Acidobacteria, Betaproteobacteria, Bacteroidetes, Verrucomicrobia, and Gemmatimonadetes. The assignment of three out of the seven selected terminal restriction fragments to members of Acidobacteria suggested that this group seems to participate frequently in the shifting of community structures that result from soil property changes. [source] Effects of hydrogeomorphic region, catchment storage and mature forest on baseflow and snowmelt stream water quality in second-order Lake Superior Basin tributariesFRESHWATER BIOLOGY, Issue 5 2003Naomi E. Detenbeck SUMMARY 1. In this study we predict stream sensitivity to non-point source pollution based on the non-linear responses of hydrological regimes and associated loadings of non-point source pollutants to catchment properties. We assessed two hydrologically based thresholds of impairment, one for catchment storage (5,10%) and one for mature forest (<50% versus >60% of catchment in mature forest cover) across two different hydrogeomorphic regions within the Northern Lakes and Forest (NLF) ecoregion: the North Shore [predominantly within the North Shore Highlands Ecological Unit] and the South Shore (predominantly within the Lake Superior Clay Plain Ecological Unit). Water quality samples were collected and analysed during peak snowmelt and baseflow conditions from 24 second-order streams grouped as follows: three in each region × catchment storage × mature forest class. 2. Water quality was affected by a combination of regional influences, catchment storage and mature forest. Regional differences were significant for suspended solids, phosphorus, nitrogen: phosphorus ratios, dissolved organic carbon (DOC) and alkalinity. Catchment storage was significantly correlated with dissolved silica during the early to mid-growing season, and with DOC, specific conductance and alkalinity during all seasons. Total nitrogen and dissolved nitrogen were consistently less in low mature forest than in high mature forest catchments. Catchment storage interacted with the influence of mature forest for only two metrics: colour and the soluble inorganic nitrogen : phosphorus ratio. 3. Significant interaction terms (region by mature forest or region by storage) suggest differences in regional sensitivity for conductance, alkalinity, total organic carbon, and colour, as well as possible shifts in thresholds of impact across region or mature forest class. 4. Use of the NLF Ecoregion alone as a basis for setting regional water quality criteria would lead to the misinterpretation of reference condition and assessment of condition. There were pronounced differences in background water quality between the North and South Shore streams, particularly for parameters related to differences in soil parent material and glacial history. A stratified random sampling design for baseflow and snowmelt stream water quality based on both hydrogeomorphic region and catchment attributes improves assessments of both reference condition and differences in regional sensitivity. [source] Estimating the Variability of Active-Layer Thaw Depth in Two Physiographic Regions of Northern AlaskaGEOGRAPHICAL ANALYSIS, Issue 2 2001Claire E. Gomersall The active layer is the zone above permafrost that experiences seasonal freeze and thaw. Active-layer thickness varies annually in response to air and surface temperature, and generally decreases poleward. Substantially less is known about thaw variability across small lateral distances in response to topography, parent material, vegetation, and subsurface hydrology. A graduated steel rod was used to measure the 1998 end-of-season thaw depth across several transects. A balanced hierarchical sampling design was used to estimate the contribution to total variance in active-layer depth at separating distances of 1, 3, 9, 27, and 100 meters. A second sampling scheme was used to examine variation at shorter distances of 0.3 and 0.1 meter. This seven-stage sample design was applied to two sites in the Arctic Foothills physiographic province, and four sites on the Arctic Coastal Plain province in northern Alaska. The spatial variability for each site was determined using ANOVA and variogram methods to compare intersite and inter-province variation. Spatial variation in thaw depth was different in the Foothills and Coastal Plain sites. A greater percentage of the total variance occurs at short lag distances (0,3 meters) at the Foothills sites, presumably reflecting the influence of frost boils and tussock vegetation on ground heat flow. In contrast, thaw variation at the Coastal Plain sites occurs at distances exceeding 10 meters, and is attributed to the influence of well-developed networks of ice-wedge polygons and the presence of drained thaw-lake basins. This information was used to determine an ongoing sampling scheme for each site and to assess the suitability of each method of analysis. [source] Utilization of semi-natural grassland through integrated generation of solid fuel and biogas from biomass.GRASS & FORAGE SCIENCE, Issue 4 2009Abstract A procedure (Integrated Generation of Solid Fuel and Biogas from Biomass, IFBB) was developed which uses a screw press to separate the readily digestible constituents of mature grassland biomass into a press fluid for conversion into biogas and a fibrous press cake for processing into a solid fuel. Effects of mechanical dehydration and prior hydrothermal conditioning at different temperatures (5, 60 and 80°C) on concentrations of organic compounds in the press fluid and on methane production in batch experiments were evaluated for five semi-natural grasslands typical of mountain areas of Germany. Results show that the crude protein concentration of the press fluids was higher and crude fibre concentration was lower than that of the parent material (herbage conserved as silage). Digestion tests in batch fermenters showed that the methane yield of the press fluids was double [397,426 normal litre (NL) kg,1 volatile solids (VS) after 13 d] that of the whole-crop grassland silage (218 NL kg,1 VS after 27 d) but no consistent effect of higher temperature during conditioning was observed. Within 13 d of fermentation the decomposition of the organic matter (OM) that occurred in the press fluids was 0·90, whereas after 27 d of fermentation more than 0·40 of the OM remained undigested in the whole-crop silage, pointing at a marked reduction in retention time for anaerobic digestion of press fluids in continuous systems. Press fluids produced 0·90 of the maximum methane yield after 4 to 7 d compared with 19 days for the whole-crop silage. [source] Potential and Pitfalls in Establishing the Provenance of Earth-Related Samples in Forensic InvestigationsJOURNAL OF FORENSIC SCIENCES, Issue 4 2006Barry G. Rawlins Ph.D. ABSTRACT: Earth scientists are often asked to establish or constrain the likely provenance of very small quantities of earth-related material as part of a forensic investigation. We tested the independent and collective interpretations of four experts with differing analytical skills in the prediction of sample provenance for three samples from different environmental settings. The methods used were X-ray diffraction, scanning electron microscopy, the assessment of pollen assemblages, and structural characterization of organic matter at the molecular level. Independent interpretations were less accurate than those where multiple techniques were combined. Collective interpretation was very effective in the assessment of provenance for two of the three sites where the mineralogy and plant communities were distinctive. At the other site, although the mineralogical analysis correctly identified the Triassic mudstone soil parent material, Carboniferous spores from domestic coal were initially interpreted as deriving directly from bedrock. Such an interpretation could be a common pitfall owing to anthropogenic redistribution of material such as coal. [source] Distribution and genesis of Fahlerden (Albeluvisols) in GermanyJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2006Peter Kühn Abstract Fahlerden dominate large areas of the young and old moraine landscapes of N and E Germany. Fahlerden (part of Fahlerden corresponds to Albeluvisols) and their transitional subtypes are supposed to have a higher intensity of clay illuviation than Parabraunerden (Luvisols). Besides this macroscopic feature reflecting periglacial influence, micromorphological features such as lenticular platy microstructure, vesicles, and fragments of clay coatings in Bt streaks document the initiation of Fahlerde genesis, which began in the Late Glacial. A model of Fahlerde genesis chronologically connects sedimentological and periglacial processes, vegetation development, and soil-forming processes like decalcification, clay illuviation, and humification. The classification criterion of larger differences in clay contents between E and Bt horizons to distinguish Fahlerden from Parabraunerden needs to be reconsidered, because most Fahlerden have developed in stratified parent material in periglacially influenced landscapes. The interpretation of a soil data base listing data of both soil types distributed in Brandenburg demonstrates that the difference in clay contents between E and Bt horizons may even be smaller in Fahlerden than in Parabraunerden. [source] Digital soil mapping in Germany,a reviewJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2006Thorsten Behrens Abstract Digital soil mapping as a tool to generate spatial soil information provides solutions for the growing demand for high-resolution soil maps worldwide. Even in highly developed countries like Germany, digital soil mapping becomes essential due to the decreasing, time-consuming, and expensive field surveys which are no longer affordable by the soil surveys of the individual federal states. This article summarizes the present state of soil survey in Germany in terms of digitally available soil data, applied digital soil mapping, and research in the broader field of pedometrics and discusses future perspectives. Based on the geomorphologic conditions in Germany, relief is a major driving force in soil genesis. This is expressed by the digital,soil mapping research which highlights the great importance of digital terrain attributes in combination with information on parent material in soil prediction. An example of digital soil mapping using classification trees in Thuringia is given as an introduction in digital soil-class mapping based on correlations to environmental covariates within the scope of the German classification system. [source] Application of ground-penetrating radar to determine the thickness of Pleistocene periglacial slope depositsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2004Daniela Sauer Abstract Wide areas of the mountainous regions of Germany have rock covered by Pleistocene periglacial slope deposits (PPSD), formed by gelifluction during the cold periods of the ice ages in non-glaciated areas. The PPSD provide the parent material for soil development, and their physical characteristics affect several stabile soil properties. Because the PPSD play a significant ecological role, we studied the spatial distribution and properties of the PPSD in order to assess the distribution of the stabile soil properties. The high stone content of the PPSD greatly hinders augering and digging. Hence, we tested the use of ground-penetrating radar (GPR) as a potentially time-saving, non-destructive method to determine the thickness of the PPSD. In several study areas of the Rhenish Massif, GPR investigations of single soil profiles and soil transects along an exposed gas-pipeline ditch were carried out. The GPR images were compared to the actual thickness of the layers of the PPSD exposed in the profiles and the ditch. In the GPR images usually at least one distinct boundary could be identified, which occurs at the transition between the loose material and the hard rock, mostly ranging between 50 and 150,cm depth. In some cases, in which stone content changed abruptly between different layers of the PPSD, also the boundaries between these layers could be identified in the GPR image. On the other hand, in areas where remnants of the Mesozoic-Tertiary weathering mantle are preserved, the boundary between the saprolite and the overlying basal layer of the PPSD is ambiguous or not at all visible. Einsatz von Georadar zur Bestimmung der Mächtigkeit periglaziärer Lagen In den deutschen Mittelgebirgen sind die Gesteine weitflächig von periglaziären Lagen überzogen. Diese entstanden durch Gelifluktion während der Kaltzeiten in den unvergletscherten Bereichen. Sie stellen das Ausgangssubstrat der Bodenbildung dar und bestimmen eine Reihe stabiler Bodeneigenschaften. Die ökologische Bedeutung der periglaziären Lagen gab den Anlass, ihre Verbreitung und Eigenschaften zu erfassen, um daraus flächenhafte Aussagen über diese Eigenschaften abzuleiten. Da Bohrungen und Grabungen in den periglaziären Lagen häufig durch hohe Skelettgehalte erschwert werden, wurde untersucht, ob Georadar zur zeitsparenden, zerstörungsfreien Erfassung der Lagenmächtigkeiten eingesetzt werden kann. In verschiedenen Teilen des Rheinischen Schiefergebirges wurden Georadar-Messungen an Bodenprofilen sowie an Transekten entlang eines Gasleitungsgrabens durchgeführt, die jeweils mit den Mächtigkeiten der periglaziären Lagen verglichen wurden, die an der Graben- bzw. Profilwand aufgeschlossen waren. In den Radargrammen ist in der Regel mindestens eine deutliche Grenze zu erkennen. Diese tritt am Übergang vom Lockermaterial zum Festgestein auf, der in der Regel zwischen 50 und 150,cm Tiefe liegt. In einigen Fällen, in denen sich der Skelettgehalt an den Lagengrenzen abrupt stark verändert, sind auch Grenzen zwischen verschiedenen Lagen im Radargramm zu erkennen. Dagegen ist in Gebieten, in denen Reste der mesozoisch-tertiären Verwitterungsdecke im Untergrund anstehen, die Grenze zwischen der Basislage und dem Gestein im Radargramm nur diffus oder nicht ausgeprägt. [source] Effects of parent material and land use on soil erodibilityJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2003Nutullah Özdemir Abstract The objective of the present investigation was to find out the effect of different parent materials and land use on soil erodibility. Four types of parent materials such as andesite, basalt, alluvial, and gypsum, and three land use types such as grass, clover, and maize, all wide spread in Erzurum Province in Turkey, were tested. Aggregate stability and soil erodibility factors were determined. The susceptibility of soils against erosion decreased in the order of parent materials basalt > andesite > alluvial > gypsum. Likewise, the susceptibility of land use can be sorted as follows: grass > clover > maize. [source] Soils and land use in the Tigray highlands (Northern Ethiopia)LAND DEGRADATION AND DEVELOPMENT, Issue 3 2008J. Nyssen Abstract Land use in a 208,ha representative catchment in the Tigray Highlands, Dogu'a Tembien district in Northern Ethiopia was studied in relation to soil geography. Typical soils are Vertisols, Vertic Cambisols, Cumulic Regosols, Calcaric Regosols and Phaeozems. Patterns of land use vary greatly within the catchment and results from ,2 -tests showed strong associations (p,<,0·001) between soil type and land use and crop production system. There is a strong association between cropland and colluvium high in basaltic content because the most fertile soils, such as Vertisols and Vertic Cambisols, have developed on this material. Preference is for autochthonous soils on in situ parent material, irrespective of the rock type, to be put under rangeland. Land use by smallholders in Dogu'a Tembien appears to be the result primarily of the interaction between environmental and social factors. Copyright © 2007 John Wiley & Sons, Ltd. [source] Australasian microtektites and associated impact ejecta in the South China Sea and the Middle Pleistocene supereruption of TobaMETEORITICS & PLANETARY SCIENCE, Issue 2 2006Billy P. Glass Unmelted ejecta were found associated with the microtektites at this site and with Australasian microtektites in Core SO95,17957,2 and ODP Hole 1144A from the central and northern part of the South China Sea, respectively. A few opaque, irregular, rounded, partly melted particles containing highly fractured mineral inclusions (generally quartz and some K feldspar) and some partially melted mineral grains, in a glassy matrix were also found in the microtektite layer. The unmelted ejecta at all three sites include abundant white, opaque grains consisting of mixtures of quartz, coesite, and stishovite, and abundant rock fragments which also contain coesite and, rarely, stishovite. This is the first time that shock-metamorphosed rock fragments have been found in the Australasian microtektite layer. The rock fragments have major and trace element contents similar to the Australasian microtektites and tektites, except for higher volatile element contents. Assuming that the Australasian tektites and microtektites were formed from the same target material as the rock fragments, the parent material for the Australasian tektites and microtektites appears to have been a fine-grained sedimentary deposit. Hole 1144A has the highest abundance of microtektites (number/cm2) of any known Australasian microtektite-bearing site and may be closer to the source crater than any previously identified Australasian microtektite-bearing site. A source crater in the vicinity of 22° N and 104° E seems to explain geographic variations in abundance of both the microtektites and the unmelted ejecta the best; however, a region extending NW into southern China and SE into the Gulf of Tonkin explains the geographic variation in abundance of microtektites and unmelted ejecta almost as well. The size of the source crater is estimated to be 43 ± 9 km based on estimated thickness of the ejecta layer at each site and distance from the proposed source. A volcanic ash layer occurs just above the Australasian microtektite layer, which some authors suggest is from a supereruption of the Toba caldera complex. We estimate that deposition of the ash occurred ,800 ka ago and that it is spread over an area of at least 3.7 times 107 km2. [source] Nutrient Dynamics of Soil Derived from Different Parent Material on Barro Colorado Island, Panama,BIOTROPICA, Issue 2 2000Joseph B. Yavitt ABSTRACT I compared the concentrations of N, P, and S in both litter and mineral soil (0,15 cm depth) from three old-growth, tropical moist forests on Barro Colorado Island (BCI), Panama. Each site was on a different substrate (i.e., parent material), but otherwise had similar climate, vegetation, and topography. There were no site differences in concentrations of N and S for either litter or soil. Concentrations of litter P and soil-extractable P were greater for the andesite (igneous rock) site than for two sites on different sedimentary rocks; however, concentrations of several other litter and soil P fractions did not differ among sites. Patterns in soil P fractions suggested advanced soil development to the point that parent material has little control of P dynamics. Litter samples from each site, leached in the laboratory, released similar amounts of N, P, and S to the soil, indicating no differences in rates of turnover in the litter and in fluxes from litter into the mineral soil among sites. I expected more site differences in soil nutrient dynamics given vastly different parent materials and soil types (i.e., Oxisol vs. Alfisol) and very shallow soil on BCI that brings the parent material close to the plant root zone. Erosion and soil mixing may explain the uniformity in soil nutrient dynamics across the sites. [source] The influence of parent material on topsoil geochemistry in eastern EnglandEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2003B. G. Rawlins Abstract The topsoil of around 10 000 km2 in eastern England has recently been sampled intensely at 4609 sites to characterize its geochemistry. The parent materials, which include both solid geology and Quaternary sediments, range in age from Permian to Holocene. The distributions of the concentrations of major and trace elements have been characterized geostatistically, and the role of parent material on their spatial structure (anisotropy) and their spatial relationships (coregionalization) have been investigated. Analysis of variance with the sites grouped by major parent material type showed that this classi,cation accounted for 14 to 48 per cent of the variance for the various elements. Global variograms of 13 elements (Al, As, Ca, Cr, Cu, Fe, Mg, Mo, Ni, P, Pb, Ti, and U) have been computed and modelled. Eleven of the variograms seem to comprise two structures, both of which we modelled with spherical functions, one of short range, 3·5 to 9 km, and the other with a range of 15 to 23 km. The models included a nugget variance, which varied from 27 per cent (for As, Fe, and Mg) to 63 per cent (for P) of the total. The long-range structures are related to the separations of the major parent materials. The variograms of several elements showed appreciable anisotropy, most notably that of Mg. Anisotropy is evident at short ranges of less than 5 km. This accords with the geological structure of the beds which dip from west to east so that their outcrops are elongated from north to south. A linear model of coregionalization ,tted to the data emphasized several important geochemical associations, which we interpret. Elements commonly associated with clay minerals (Mg, Al) and the clay size fraction (Ti) are dominated by the long-range structure of the coregionalization, whilst several trace elements (As, Cr, Ni and U) are spatially correlated with Fe over short distances, through adsorption of the former on the surfaces of Fe oxyhydroxides. The topsoil around large urban areas is enriched in lead, but it is not clear whether anthropogenic sources are responsible for this metal's anomalous spatial relationships with other elements. Crown copyright © 2003. Reproduced with the permission of Her Majesty's Stationery Of,ce. Published by John Wiley & Sons, Ltd. [source] Poorly crystalline mineral phases protect organic matter in acid subsoil horizonsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 6 2005M. Kleber Summary Soil minerals are known to influence the biological stability of soil organic matter (SOM). Our study aimed to relate properties of the mineral matrix to its ability to protect organic C against decomposition in acid soils. We used the amount of hydroxyl ions released after exposure to NaF solution to establish a reactivity gradient spanning 12 subsoil horizons collected from 10 different locations. The subsoil horizons represent six soil orders and diverse geological parent materials. Phyllosilicates were characterized by X-ray diffraction and pedogenic oxides by selective dissolution procedures. The organic carbon (C) remaining after chemical removal of an oxidizable fraction of SOM with NaOCl solution was taken to represent a stable organic carbon pool. Stable organic carbon was confirmed as older than bulk organic carbon by a smaller radiocarbon (14C) content after oxidation in all 12 soils. The amount of stable organic C did not depend on clay content or the content of dithionite,citrate-extractable Fe. The combination of oxalate-extractable Fe and Al explained the greatest amount of variation in stable organic C (R2 = 0.78). Our results suggest that in acid soils, organic matter is preferentially protected by interaction with poorly crystalline minerals represented by the oxalate-soluble Fe and Al fraction. This evidence suggests that ligand exchange between mineral surface hydroxyl groups and negatively charged organic functional groups is a quantitatively important mechanism in the stabilization of SOM in acid soils. The results imply a finite stabilization capacity of soil minerals for organic matter, limited by the area density of reactive surface sites. [source] Enhanced Adsorption of Ammonia on Metal-Organic Framework/Graphite Oxide Composites: Analysis of Surface InteractionsADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Camille Petit Abstract Composites of the metal-organic framework (MOF), MOF-5, and graphite oxide (GO) with different ratios of the two components are prepared and tested in ammonia removal under dry conditions. The parent and composite materials are characterized before and after exposure to ammonia by sorption of N2, X-ray diffraction, thermal analyses, and FT-IR spectroscopy. The results show a synergetic effect resulting in an increase in the ammonia uptake compared to the parent materials. It is linked to enhanced dispersive forces in the pore space of the composites. Additionally, ammonia interacts with zinc oxide tetrahedra via hydrogen bonding and is intercalated between the layers of GO. Retention of a large quantity of ammonia eventually leads to a collapse of the MOF-5 structure in the composites. The effect resembles that observed when MOF-5 is exposed to water. Taking into account the similarity of ammonia and water molecules, it is hypothesized that ammonia causes a destruction of the MOF-5 and composite structure as a result of its hydrogen bonding with the zinc oxide clusters. [source] Soil parent materials and the pottery of Roman Galilee: A comparative studyGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 4 2002Moshe Wieder The paper presents a comparative micromorphological analysis of the range of soil materials used to make the pottery of the hilly Galilee during the Roman period, and the ceramic products made from these materials. The four soil units that served as raw material for most of the pottery made in this period and region are examined along with pottery derived from each of them. For each soil unit, the soil characteristics and processes are described, followed by a presentation of the micromorphological characteristics of the soil material and those of the pottery made from that material. The contribution of the aeolian dust component to the soil materials is discussed as well as the identification of the tempering materials (nonplastics or other soil materials) added to the pottery paste. The study demonstrates the close correlation in microfabric between the pottery and original soil materials, sheds light on the raw material selection and modification practices of the potters of Roman Galilee, and has significant implications for provenance studies, using chemical analysis, on the pottery of this period and region. © 2002 Wiley Periodicals, Inc. [source] Accumulation soils like "Ockererde",forgotten soil units in soil-classification systemsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2005Sabine Fiedler Abstract Accumulation soils like those known as "Ockererde" are not yet represented in the German and in international soil-classification systems, even though they represent important members of catenas found in humid low-mountain areas influenced by the translocation of interpedon matter. Currently, this soil is referred to as "(Hang-)Oxigley", though this does not take into account its water and matter dynamics. Six representative catenas in the Black Forest (SW Germany) will be used to describe the occurrence, extent, and properties of the accumulation-affected "Ockererde" derived from a variety of parent materials at specific altitudes. On the basis of their morphological, chemical, and physical properties as well as matter dynamics, it is possible to distinguish "Ockererde" clearly from soil units with similar characteristics ("Lockerbraunerde", Andosols). Finally, suggestions will be given for the classification of "Ockererde". Akkumulationsböden wie die ,Ockererde" , nicht berücksichtigte Bodentypen innerhalb der Bodensystematik Durch allochthone Akkumulation geprägte Böden sind bislang ebenso wie in der internationalen auch in der deutschen Bodensystematik nicht enthalten. Am Beispiel der so genannten ,Ockererde" wird gezeigt, dass Akkumulationsböden wichtige Glieder der durch Stoffverlagerung gekennzeichneten Bodengesellschaften kühl-humider Mittelgebirgslagen darstellen. Momentan wird die ,Ockererde" in der deutschen Bodensystematik als ,(Hang-)Oxigley" angesprochen, was jedoch weder der bodenspezifischen Wasser- noch der Stoffdynamik gerecht wird. Anhand von sechs typischen Catenen (Buntsandstein, Gneiss, Granit) aus dem Schwarzwald (900 bis 2000 mm Jahresniederschlag), die die ,Ockererde" einschließen, wird deren Verbreitung, Merkmalscharakteristik und Stoffdynamik beschrieben. Auf Grundlage dessen wird eine klare Abgrenzung der ,Ockererde" zu Bodeneinheiten mit ähnlichen Eigenschaften (Lockerbraunerde, andische Braunerden, (Hang-)Oxigley) vorgenommen und ein Vorschlag zur Bezeichnung und Einordnung innerhalb der Deutschen Bodenklassifikation unterbreitet. [source] Effects of parent material and land use on soil erodibilityJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 6 2003Nutullah Özdemir Abstract The objective of the present investigation was to find out the effect of different parent materials and land use on soil erodibility. Four types of parent materials such as andesite, basalt, alluvial, and gypsum, and three land use types such as grass, clover, and maize, all wide spread in Erzurum Province in Turkey, were tested. Aggregate stability and soil erodibility factors were determined. The susceptibility of soils against erosion decreased in the order of parent materials basalt > andesite > alluvial > gypsum. Likewise, the susceptibility of land use can be sorted as follows: grass > clover > maize. [source] Synthesis and self-assembly of fluorinated block copolymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2002Marc A. Hillmyer Abstract Fluorinated block copolymers combine the unique properties of fluoropolymers and the intriguing self-assembly of hybrid macromolecules. The preparation of the title molecules by selective fluorination procedures and the effect of fluorine incorporation on the material thermodynamics are presented. We highlight two fluorination schemes developed in our laboratory, difluorocarbene and perfluoroalkyliodide additions to polydienes, that allow for the selective and tunable incorporation of different fluorinated groups into model block copolymers. The fluorination changes the physical properties of the parent materials and leads to interesting changes in the component incompatibilities. The role of fluorination in determining block copolymer thermodynamics in both the solid state and in solution and in ultimately exploiting fluorination to produce novel, higher order structures is central to our research efforts. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 1,8, 2002 [source] Soil Nitrogen Pools Associated with Revegetation of Disturbed Sites in the Lake Tahoe AreaRESTORATION ECOLOGY, Issue 2 2002V. P. Claassen Abstract Thin, poorly developed soils in the high elevation, summer-dry environment near Lake Tahoe, California are easily disturbed by anthropogenic impacts. Subsoils and parent materials that are exposed by vegetation removal and topsoil erosion or by burial during construction activities are difficult to revegetate and may continue to erode for decades after disturbance. The resulting sediment loads contribute to decreased water quality in local watersheds and to the loss of clarity in Lake Tahoe. Field observations suggest that soil disturbance often results in depletion of soil nitrogen (N) reserves and that the remaining substrates may be unable to provide adequate N for revegetation. To quantify the levels of soil N that are associated with higher levels of percent plant cover on previously disturbed soils in the Lake Tahoe area, a basin-wide survey and a second paired site study were conducted. Results indicate that extractable ammonium and nitrate levels correlate poorly with percent vegetative cover, whereas the correlations of anaerobically mineralizable N and total N are stronger and account for nearly 50% of the variability in plant cover data. Sites with plant cover measuring greater than 40% are associated with total soil N levels of about 1,200 kg N/ha and anaerobic mineralizable N levels of about 26 kg N/ha. Despite high concentrations of N in the surface soils, a large fraction of the N in the 0- to 50-cm profile occurs below 30 cm, when measured on a landscape basis. [source] Nutrient Dynamics of Soil Derived from Different Parent Material on Barro Colorado Island, Panama,BIOTROPICA, Issue 2 2000Joseph B. Yavitt ABSTRACT I compared the concentrations of N, P, and S in both litter and mineral soil (0,15 cm depth) from three old-growth, tropical moist forests on Barro Colorado Island (BCI), Panama. Each site was on a different substrate (i.e., parent material), but otherwise had similar climate, vegetation, and topography. There were no site differences in concentrations of N and S for either litter or soil. Concentrations of litter P and soil-extractable P were greater for the andesite (igneous rock) site than for two sites on different sedimentary rocks; however, concentrations of several other litter and soil P fractions did not differ among sites. Patterns in soil P fractions suggested advanced soil development to the point that parent material has little control of P dynamics. Litter samples from each site, leached in the laboratory, released similar amounts of N, P, and S to the soil, indicating no differences in rates of turnover in the litter and in fluxes from litter into the mineral soil among sites. I expected more site differences in soil nutrient dynamics given vastly different parent materials and soil types (i.e., Oxisol vs. Alfisol) and very shallow soil on BCI that brings the parent material close to the plant root zone. Erosion and soil mixing may explain the uniformity in soil nutrient dynamics across the sites. [source] | |||||||||||||||||||