Polycyclic Aromatic Hydrocarbons Content in Contaminated Forest Soils with Different Humus Types.

PubMed

Lasota, Jarosław; Błońska, Ewa

2018-01-01

The aim of the study was to determine polycyclic aromatic hydrocarbon (PAH) content in different forest humus types. The investigation was carried out in Chrzanów Forest District in southern Poland. Twenty research plots with different humus types (mor and mull) were selected. The samples for analysis were taken after litter horizons removing from a depth of 0-10 cm (from the Of- and Oh-horizon total or A-horizon). pH, organic carbon and total nitrogen content, base cations, acidity, and heavy metal content were determined. In the natural moisture state, the activity of dehydrogenase was determined. The study included the determination of PAH content. The conducted research confirms strong contamination of study soil by PAHs and heavy metals. Our experiment provided evidence that different forest humus types accumulate different PAH amounts. The highest content of PAHs and heavy metals was recorded in mor humus type. The content of PAHs in forest humus horizon depends on the content and quality of soil organic matter. Weaker degradation of hydrocarbons is associated with lower biological activity of soils. The mull humus type showed lower content of PAHs and at the same time the highest biological activity confirmed by high dehydrogenase activity.

Dark gray soils on two-layered deposits in the north of Tambov Plain: Agroecology, properties, and diagnostics

NASA Astrophysics Data System (ADS)

Zaidelman, F. R.; Nikiforova, A. S.; Stepantsova, L. V.; Volokhina, V. P.

2012-05-01

Dark gray soils in the Tambov Plain are developed from the light-textured glaciofluvial deposits underlain by the calcareous loam. Their morphology, water regime, and productivity are determined by the depth of the slightly permeable calcareous loamy layer, relief, and the degree of gleyzation. The light texture of the upper layer is responsible for its weak structure, high density, the low content of productive moisture, and the low water-holding capacity. If the calcareous loam is at a depth of 100-130 cm, dark gray soils are formed; if it lies at a depth of 40-70 cm, temporary perched water appears in the profile, and dark gray contact-gleyed soils are formed. Their characteristic pedofeatures are skeletans in the upper layers, calcareous nodules in the loamy clay layer, and iron nodules in the podzolized humus and podzolic horizons. The appearance of Fe-Mn concretions is related to gleyzation. The high yield of winter cereals is shown to be produced on the dark gray soils; the yields of spring crops are less stable. Spring cereals should not be grown on the contact-gleyed dark gray soils.

Carbon and Nitrogen dynamics in forest soils depending on light conditions and tree species

NASA Astrophysics Data System (ADS)

Veselinovic, Bojana; Hager, Herbert

2013-04-01

Climate change mitigation actions under the Kyoto Protocol apply among other decreases of CO2-emissions and/or increases of carbon (C) stocks. As soils represent the second biggest C-reservoir on Earth, an exact estimation of the stocks and reliable knowledge on C-dynamics in forest soils is of high importance. Anyhow, here, the accurate GHG-accounting, emission reductions and increase in C stocks is hampered due to lack of reliable data and solid statistical methods for the factors which influence C-sequestration in and its release from these systems. In spite of good progress in the scientific research, these factors are numerous and diverse in their interactions. This work focuses on influence of the economically relevant tree species - Picea abies, Fagus sylvatica and Quercus spp. - and light conditions on forest floor and mineral soil C and N dynamics in forest soils. Spruce monocultures have been widely used management practices in central European forests during the past century. Such stands are in lower altitudes and on heavy and water logged soils unstable and prone to disturbances, especially to windthrows. We hypothesize that windthrow areas loose C & N and that the establishment of the previous nutrient stocks is, if at all, only possible to be reached over the longer periods of time. We research also how the increased OM depletion affects the change of C & N stocks in forest floor vs. mineral soil. Conversion of such secondary spruce monocultures to site adequate beech and oak forests may enable higher stocks allocated predominantly as stable organic carbon and as plant available nitrogen. For this purpose sites at 300-700 m altitude with planosols were chosen in the region of the Northern Alpine Foothills. A false chronosequence approach was used in order to evaluate the impacts of the tree species and change in light conditions on dynamic of C & N in the forest floor and mineral soil, over the period 0-100 (for oak 120 y.) years. The C- and N-pools were estimated for different compartments over the available age classes. The sampling of humus and surface vegetation was done using 30x30 and 50x50 cm frame. It was distinguished between following fractions: fine/coarse roots ( than 2 mm), woody debris (dead wood, branches, cones and acorns), living vegetation (ground vegetation and its roots), litter (leaves fresh and decomposed coarse organic layer) and humus (more than 30% of fine organic matter). C and N stocks in mineral soil were assessed for the 10, 30 and 60 cm depth. Furthermore, the influence of solar radiation on humus and mineral soil C and N was evaluated using the GSF (global site factor) estimated with hemispherical photography. The photographs were taken on each sampling point using the 180_ viewing angle looking upward into the canopy. As expected, the solar energy strongly influences the occurrence of herbaceous layer in spruce and oak stands. Furthermore, beech and oak chronosequences display positive (although not strong) correlation between the light factor and C & N accumulation in the humus fractions. In the beech chronosequence, good correlation with light conditions in stands is only found in the sum of all forest floor compartments (litter, woody debris and humus). On the contrary, with exception of spruce (r = 0.391** for the 10 cm depth) no significant correlation was found with the mineral soil C for the three observed depths. depths.

Responses of fungal and plant communities to partial humus removal in mid-boreal N-enriched forests.

PubMed

Tarvainen, Oili; Hamberg, Leena; Ohenoja, Esteri; Strömmer, Rauni; Markkola, Annamari

2012-10-15

Partial removal of the forest humus layer was performed in nitrogen-enriched urban Scots pine forest stands in the northern Finland in order to improve soil conditions for ectomycorrhizal (ECM) fungi, important symbionts of trees. Aboveground part of understory vegetation and the uppermost half of the humus layer were removed (REMOVAL treatment) from sample plots in six urban and eight rural reference forest sites at the beginning of the 2001 growing season. During the seasons 2001-2005, we inventoried sporocarp production of ECM and saprophytic fungi, and in 2003 the recovery of understory vegetation. The REMOVAL treatment resulted in a higher number of fruiting ECM species and sporocarps than controls at the rural, but not at urban sites. The sporocarp number of saprophytic fungi declined in the REMOVAL subplots at the urban sites. The recovery of bryophytes and lichens in the REMOVAL treatment was slow at both the urban and rural sites, whereas Vaccinium dwarf shrub cover, and herb and grass cover returned rapidly at the urban sites. We conclude that the partial vegetation and humus layer removal as a tool to promote the reproduction of ECM fungal species is limited in the boreal urban forests. Copyright © 2012 Elsevier Ltd. All rights reserved.

Permafrost in vegetated scree slopes below the timberline - characterization of thermal properties and permafrost conditions by temperature measurements and geoelectrical monitoring

NASA Astrophysics Data System (ADS)

Schwindt, Daniel; Kneisel, Christof

2010-05-01

Discontinuous alpine permafrost is expected to exist at altitudes above 2400m a.s.l. at mean annual air temperatures (MAAT) of less than -1°C. Below timberline only a few sites are known, where sporadic permafrost exists in vegetated talus slopes with positive MAAT. Aim of the study is to characterize permafrost-humus interaction, the thermal regime and its influence on temporal and spatial permafrost variability. Results of geophysical and thermal measurements from three talus slopes, located in the Swiss Alps (Engadin, Appenzell) at elevations between 1200 and 1800m a.s.l. with MAAT between 2.8°C and 5.5°C are presented. Parent rock-material of the slopes are granite (Bever Valley, Engadin) and dolomite (Susauna Valley, Engadin; Brüeltobel, Appenzell). Joint application of electrical resistivity tomography (ERT) and refraction seismic tomography (RST) is used to detect and characterize permafrost. To observe temporal and spatial variability in ice content and characteristics year-around geoelectrical monitoring and quasi-3D ERT are used. A forward modeling approach has been applied to validate the results of geoelectrical monitoring. A number of temperature data loggers were installed in different depth of the humus layer and in different positions of the slope to monitor the ground thermal regime. Isolated permafrost has been detected by the combination of ERT and RST in the lower parts of the investigated talus slopes. Results from geophysical measurements and monitoring indicate a high spatial and temporal variability in ice content and ice characteristics (temperature, density, content of unfrozen water) for all sites. A distinct rise of resistivities between November and December indicates a decrease of unfrozen water content, caused by a pronounced cooling in the lower parts of the slope. Decreasing ice content and extent of the permafrost lenses can be observed in decreasing seismic velocities from 2600m/sec in spring to only 1500m/sec in October. Ice characteristics, ice content and extent of permafrost lenses depend on the thermal regime, induced by characteristics of surface (humus, vegetation) and subsurface (parental rock material) material as well as thermal effects, with an inversive air flow inside the talus slope of cold air inflow in winter in the lower parts and cold air outflow in summer through the same vents (chimney effect), a theory that has been proven by temperature measurements in the Brüeltobel and the Susauna Valley. While the dolomitic talus slopes are relatively homogenous concerning surface and subsurface material, showing a consistent thick humus cover, the granitic site shows a small-scale heterogeneity of different humus forms and thicknesses as well as size of granitic boulders, influencing the thermal regime. Temperatures in the humus profile are very constant for the dolomitic sites, reflecting the insulation capability of the humus cover, with temperatures in August around 3°C at 30cm depth (mean air temperature in August 12°C). Humus temperatures (30cm depth) in the Bever Valley vary strongly between areas with consistent humus cover (1-2°C in August) and areas with coarse, uncovered boulders, where temperatures show a stronger coupling to air temperatures. While the chimney effect has strong influence on the ground thermal regime of the dolomitic sites, for some parts of the granitic slope in the Bever Valley the theory has to be expanded towards a continuous air exchange with the atmosphere, for areas where the insulation capability of the humus cover is highly disturbed along large parts of the talus slope.

Soil Organic Carbon Pool and Its Chemical Composition in Phyllostachy pubescens Forests at Two Altitudes in Jian-ou City, China.

PubMed

Ji, Haibao; Zhuang, Shunyao; Zhu, Zhaoliang; Zhong, Zheke

2015-01-01

Phyllostachys pubescens forests play an important role in soil organic carbon (SOC) sequestration in terrestrial ecosystems. However, the estimation and mechanism of SOC sequestration by P. pubescens forests remain unclear. In this study, the effect of P. pubescens forest distribution with elevation was investigated at two altitude sites in Jian-ou City, Southeast China. SOC storage was estimated and its chemical composition was obtained via 13C-nuclear magnetic resonance (NMR), chemical classification, and spectral analysis. Results showed that the SOC contents and stocks were significantly higher at the high-altitude site than at the low-altitude site in the entire soil profile (0-60 cm). The C contents of the three combined humus forms exhibited similar responses to the elevation change, and all of these forms were higher at the high-altitude site than at the low-altitude site regardless of soil layer. However, the proportions of the three combined humus C showed no significant differences between the two altitudes. The results of 13C-NMR showed that the SOC chemical composition did not significantly vary with elevation as well. This finding was consistent with the E465/E665 of the loosely combined humus. Overall, the results suggested that altitude should be considered during regional SOC estimation and that altitude affected the quantity rather than the quality of the SOC under the same P. pubescens vegetation.

Soil Organic Carbon Pool and Its Chemical Composition in Phyllostachy pubescens Forests at Two Altitudes in Jian-ou City, China

PubMed Central

Ji, Haibao; Zhuang, Shunyao; Zhu, Zhaoliang; Zhong, Zheke

2015-01-01

Phyllostachys pubescens forests play an important role in soil organic carbon (SOC) sequestration in terrestrial ecosystems. However, the estimation and mechanism of SOC sequestration by P. pubescens forests remain unclear. In this study, the effect of P. pubescens forest distribution with elevation was investigated at two altitude sites in Jian-ou City, Southeast China. SOC storage was estimated and its chemical composition was obtained via 13C-nuclear magnetic resonance (NMR), chemical classification, and spectral analysis. Results showed that the SOC contents and stocks were significantly higher at the high-altitude site than at the low-altitude site in the entire soil profile (0–60 cm). The C contents of the three combined humus forms exhibited similar responses to the elevation change, and all of these forms were higher at the high-altitude site than at the low-altitude site regardless of soil layer. However, the proportions of the three combined humus C showed no significant differences between the two altitudes. The results of 13C-NMR showed that the SOC chemical composition did not significantly vary with elevation as well. This finding was consistent with the E465/E665 of the loosely combined humus. Overall, the results suggested that altitude should be considered during regional SOC estimation and that altitude affected the quantity rather than the quality of the SOC under the same P. pubescens vegetation. PMID:26716688

A tracer experiment to study flow paths of water in a forest soil

NASA Astrophysics Data System (ADS)

Feyen, H.; Wunderli, H.; Wydler, H.; Papritz, A.

1999-12-01

This contribution discusses a tracer experiment, which was performed to study the flow paths of water in a macroporous forest soil. The experiment was performed in the framework of a study on the cycling of nitrogen in forested Prealpine catchments, in which losses of nitrate from virtually pristine areas were observed. Two soil plots with distinct micro-topography and top-soil were investigated: a well drained mor humus on a mound and a wet muck humus in a small depression. To reveal the effect of the soil horizons on the flow regime, tracers were applied both onto the soil surface and injected into the sub-soil. Tracers injected directly into the gleyic sub-soil reached the outlet (at a distance of 3.3 m) about 1000 times faster than could be expected from the saturated hydraulic conductivity of the soil matrix. Peak concentrations were observed after 18 (muck humus, tracer recovery 31%) to 70 min (mor humus, tracer recovery 40%). The peak concentration was 10 times smaller on the drier mor humus plot as compared to the muck humus. The mobile water content of the sub-soil varied between 0.5 (muck humus) and 1.3% (mor humus) of the total available soil water. The discrepancy in residence time, peak concentration and volume of mobile water between both sub-soils can be attributed to the differently structured sub-soil (longer travel distance and mixing volume in the drier mor humus). Tracers applied onto the soil surface resulted in a much slower breakthrough (tracer peaks after 400-700 min). Thus, in contrast to the sub-soil, flow through the matrix was the predominating transport process in the upper humus layers of both plots.

Effects of brash removal after clear felling on soil and soil-solution chemistry and field-layer biomass in an experimental nitrogen gradient.

PubMed

Ring, E; Högbom, L; Nohrstedt, H O

2001-10-12

Biofuels, such as brash from forest fellings, have been proposed as an alternative energy source. Brash removal may affect the sustainability of forest production, e.g., through a change in the availability of cations and N in the soil. We report initial effects of brash removal on inorganic N content in humus and mineral soil, soil-solution chemistry, and field-layer biomass after clear felling an N-fertilisation experiment in central Sweden. The experiment comprised six different fertiliser levels, ranging from 0 to 600 kg N ha(-1). Urea was given every 5th year during 1967 to 1982 to replicated plots, giving total doses of 0 to 2400 kg N ha(-1). Clear felling took place in 1995, 13 years after the last fertilisation. The removal of brash decreased the NO3- content in the humus layer after clear felling. A decrease in the NO3- concentration of the soil solution was indicated during most of the study period as well. No effect of the previous N fertilisation was found in the humus layer, but in the mineral soil there was an increase in NO3- content for the highest N dose after clear felling ( p = 0.06). The soil-solution chemistry and the field-layer biomass showed an irregular pattern with no consistent effects of brash removal or previous fertilisation.

A comparative assessment of the biological properties of soils in the cultural and native cenoses of the Central Caucasus (using the example of the Terskii variant of altitudinal zonality in Kabardino-Balkaria)

NASA Astrophysics Data System (ADS)

Gorobtsova, O. N.; Gedgafova, F. V.; Uligova, T. S.; Tembotov, R. Kh.

2016-01-01

The biological properties of the most widespread automorphic and hydromorphic soils of cultural and native cenoses in the Terskii variant of the altitudinal zonality (Kabardino-Balkaria) are compared. The data on the humus reserves in the 0- to 20-cm soil layer and those on the carbon content in the microbial biomass calculated on the basis of the results of substrate-induced respiration measurements are presented. The share of carbon in the microbial biomass of the total organic carbon in the soils was determined. Long-term (more than 70 years) farming on the studied soils significantly changed their biological properties. The humus content and its reserves became lower by 25-40%. The physiological activity of the microbial biomass in the cultural soils decreased by more than 60%. Presently, the soils of the cultural cenoses function as an entire natural system, but at a lower level of fertility; the loss of more than 30% of the bioorganic potential (the critical threshold of soil system stability) indicates the disturbance of soil ecological functions, their stability, and the capability of self-restoration.

BOREAS HYD-9 Belfort Rain Gauge Data

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Kouwen, Nick; Soulis, Ric; Jenkinson, Wayne; Graham, Allyson; Knapp, David E. (Editor); Smith, David E. (Technical Monitor)

2000-01-01

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-6 team collected several data sets related to the moisture content of soil and overlying humus layers. This data set contains water content measurements of the moss/humus layer, where it existed. These data were collected along various flight lines in the Southern Study Area (SSA) and Northern Study Area (NSA) during 1994. The data are available in tabular ASCII files. The HYD-9 Belfort rain gauge data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Degradability of dissolved soil organic carbon and nitrogen in relation to tree species.

PubMed

Kiikkilä, Oili; Kitunen, Veikko; Smolander, Aino

2005-06-01

The degradability and chemical characteristics of water-extractable dissolved organic carbon (DOC) and nitrogen (DON) from the humus layer of silver birch (Betula pendula Roth), Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands were compared in short-term incubation of soil solutions. For all extracts the degradation of DOC and DON was low (12-17% loss) and increased in the order: birch, spruce and pine. In the humus layer under pine a relatively larger pool of rapidly degrading dissolved soil organic matter (DOM) was indicated by the [3H]thymidine incorporation technique, which measures the availability of DOM to bacteria. The degradation of DOC was explained by a decrease in the hydrophilic fraction. For DON, however, both the hydrophilic and hydrophobic fractions tended to decrease during incubation. No major differences in concentrations of hydrophilic and hydrophobic fractions were detected between tree species. Molecular size distribution of DOC and DON, however, revealed slight initial differences between birch and conifers as well as a change in birch extract during incubation. The depletion of very rapidly degrading fractions (e.g., root exudates and compounds from the litter) may explain the low degradability of DOM in the humus layer under birch.

Comparison on humus and soil geochemical baselines in Southern Finland

NASA Astrophysics Data System (ADS)

Minolfi, Giulia; Tarvainen, Timo; Jarva, Jaana

2016-04-01

Humus has been recognized since a survey in 1977 (Allen and Steinnes, 1980) as one of the best sampling media for mapping regional environmental contamination because of the strong geochemical contrast between anomalous and background concentrations resulting from its capacity to accumulate high levels of trace metals. This study is in the framework of the comparison between humus, topsoil and moss deposition data, in order to analyze the humus behavior and to find possible similarities to underlying geology and long-range atmospheric deposition. The analyzed samples are part of a geochemical mapping programme carried out by the Geological Survey of Finland (GTK); subsoil, topsoil and humus samples have been collected in a large area in Southern Finland since 2002. 816 sample pairs (humus and topsoil samples) were selected for statistical analysis. Statistical graphs, like histograms, CP plots and box plots, were realized for 31 elements, and showed that most of the elements have completely different distribution of concentrations in humus and in topsoil samples. Then the correlation between the element concentrations in humus and minerogenic topsoil has been evaluated measuring the Spearman rank correlation value and elaborating scatter plots between the element concentrations in humus and minerogenic topsoil, and between the content of the element vs. the content of organic C. The concentrations of some elements, like K, Mg, Fe, Al, in humus samples are controlled by the content of mineral matter, derived by the soil dust. Other elements, such as As, Bi, Cd, Co, Cu, Mn, Mo, Ni, Pb, Rb, Th, V and Zn showed evident outliers, with probable anthropogenic origin. In order to explain these anomalous high values in humus, the geographic distributions of these elements in humus and topsoil were analyzed and then compared to the deposition data obtained by the national moss data. High values appear in areas where the anthropogenic impact is strong, like the Harjavalta area, where older emissions from the smelter still cause anomaly patterns in some elements, and the more densely populated and industrialized areas, like the city of Tampere and the coastline from Porvoo to the capital region of Helsinki. According to the results presented here, the humus concentrations are more affected by the atmospheric impact than by the lithogenic contributes. Because of the great anthropogenic influence on humus concentrations, that causes locally high anomalies, even after many years, new humus samples should be collected, in order to improve the knowledge about humus behavior and anthropogenic input to the topmost layer of ground surface. REFERENCES Allen, R. O., & Steinnes, E. 1980. Contribution from long-range atmospheric transport to the heavy metal pollution of surface soil. D Drabløs, A Tollan (Eds.), Ecological impact of acid precipitation, SNSF Project, Oslo-Ås (1980), pp. 102-103.

Considerations over the distribution of the organic matter in the soil cover of Transylvania Plain (Romania)

NASA Astrophysics Data System (ADS)

Cacovean, Horia; Man, Titus; Rusu, Teodor

2010-05-01

Considerations over the distribution of the organic matter in the soil cover of Transylvania Plain (Romania) Horea Cacovean*, Titus Man**, Teodor Rusu*** *OSPA-Cluj- 1Faglui street, Cluj Napoca, RO-40048, Romania- turda75@yahoo.com ** Faculty of Geographie, University of Babes-Bolyai, 5-7 Clinicilor street, Cluj Napoca, RO-400006, Romania *** Faculty of Agriculture, USAMV, 3-5 Calea Manastur street,Cluj Napoca, RO-400372, Romania Soil degradation has become a major concern in the Transylvania Plain. Erosion, landslides, salinization, gleysation, and loss of humus are the main forms of soil deterioration in that region. This factsheet deals with the role of organic matter in soil productivity and the effects of various management practices and abandonment of the lands on soil organic matter. Soils in Transylvania Plain are analyzed concerning the amount of humus they contain. The influence of soil texture, climatic variables, and soil management on the qualitative soil humus content was studied in the top 20 cm of different managed loess soils of more then 100 profiles along a climosequence in that region. Taken together, soil, landform, land use and vegetation data suggest: (1) summit positions are relatively stable with immobilizing humus environments; (2) the content of humus increase progressively down steep at the contact with the floodplains; 3) without the influx of organic materials, erodible backslopes may become humus depleted as it happen the poor inputs of grassland and forest litter are mixed with surface soil horizon; 4) influx of mixed sediment and organic materials from backslopes maintains concentrations of humus on footslopes and toeslopes. This influence was more pronounced in the heavy clayey soils, suggesting that the accumulation of humus was enhanced by organo-mineral interactions. Entrenchment of drainage ways can circumvent these translocation processes. The results underscore the importance of functional connectivity between upland hillslopes and alluvial soils.

[Spatial heterogeneity and influencing factors of soil phosphorus concentration in a mid-subtropical Choerospondias axillaris deciduous broad-leaved forest, China.

PubMed

Hu, Rui Bin; Fang, Xi; Xiang, Wen Hua; Jiang, Fang; Lei, Pi Feng; Zhao, Li Juan; Zhu, Wen Juan; Deng, Xiang Wen

2016-03-01

In order to investigate spatial variations in soil phosphorus (P) concentration and the influencing factors, one permanent plot of 1 hm 2 was established and stand structure was surveyed in Choerospondias axillaries deciduous broadleaved forest in Dashanchong Forest Park in Changsha County, Hunan Province, China. Soil samples were collected with equidistant grid point sampling method and soil P concentration and its spatial variation were analyzed by using geo-statistics and geographical information system (GIS) techniques. The results showed that the variations of total P and available P concentrations in humus layer and in the soil profile at depth of 0-10, 10-20 and 20-30 cm were moderate and the available P showed higher variability in a specific soil layer compared with total P. Concentrations of total P and available P in soil decreased, while the variations increased with the increase in soil depth. The total P and available P showed high spatial autocorrelation, primarily resulted from the structural factors. The spatial heterogeneity of available P was stronger than that of total P, and the spatial autocorrelation ranges of total P and available P varied from 92.80 to 168.90 m and from 79.43 to 106.20 m in different soil layers, respectively. At the same soil depth, fractal dimensions of total P were higher than that of available P, with more complex spatial pattern, while available P showed stronger spatial correlation with stronger spatial structure. In humus layer and soil depths of 0-10, 10-20 and 20-30 cm, the spatial variation pattern of total P and available P concentrations showed an apparent belt-shaped and spot massive gradient change. The high value appeared at low elevation and valley position, and the low value appeared in the high elevation and ridge area. The total P and available P concentrations showed significantly negative correlation with elevation and litter, but the relationship with convexity, species, numbers and soil pH was not significant. The total P and available P exhibited significant positive correlations with soil organic carbon (SOC), total nitrogen concentration, indicating the leaching characteristics of soil P. Its spatial variability was affected by many interactive factors.

Factors responsible for Ixodes ricinus nymph abundance: Are soil features indicators of tick abundance in a French region where Lyme borreliosis is endemic?

PubMed

Goldstein, Valérie; Boulanger, Nathalie; Schwartz, Dominique; George, Jean-Claude; Ertlen, Damien; Zilliox, Laurence; Schaeffer, Mickaël; Jaulhac, Benoît

2018-05-01

In Europe, the hard tick Ixodes ricinus (Acari: Ixodidae) is the main vector of Lyme borreliosis spirochetes (Borrelia burgdorferi sensu lato group). A field study was conducted to evaluate the abundance of Ixodes nymphs in the French region of Alsace, where Lyme borreliosis is endemic, and to determine whether environmental factors such as soil moisture and composition may be associated with nymph abundance. In the ten sites studied, ticks were collected by drag sampling from March to October in 2013 and 2014. Temperature, relative humidity, saturation deficit, soil pH, humus composition and type of vegetation were recorded at each site. The abundance of I. ricinus was highly variable from one site to another. Inter-annual variations were also observed, since the nymph abundance were higher in 2013 than in 2014. This study shows that humus type can be indicative of nymph abundance. Three types of humus were observed: (1) moder, (2) mull, and (3) mull-moder humus. One of them, moder humus, which is characterized by a thick layer of fragmented leaves, was found in multivariate analyses to be strongly associated with the nymph abundance. This study demonstrates that factors such as saturation deficit do not suffice to explain the differences in nymph abundance among sites. The composition of the soil and especially the type of humus should also be taken into consideration when assessing acarological risk. Copyright © 2018 Elsevier GmbH. All rights reserved.

ForCent model development and testing using the Enriched Background Isotope Study experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parton, W.J.; Hanson, P. J.; Swanston, C.

The ForCent forest ecosystem model was developed by making major revisions to the DayCent model including: (1) adding a humus organic pool, (2) incorporating a detailed root growth model, and (3) including plant phenological growth patterns. Observed plant production and soil respiration data from 1993 to 2000 were used to demonstrate that the ForCent model could accurately simulate ecosystem carbon dynamics for the Oak Ridge National Laboratory deciduous forest. A comparison of ForCent versus observed soil pool {sup 14}C signature ({Delta} {sup 14}C) data from the Enriched Background Isotope Study {sup 14}C experiment (1999-2006) shows that the model correctly simulatesmore » the temporal dynamics of the {sup 14}C label as it moved from the surface litter and roots into the mineral soil organic matter pools. ForCent model validation was performed by comparing the observed Enriched Background Isotope Study experimental data with simulated live and dead root biomass {Delta} {sup 14}C data, and with soil respiration {Delta} {sup 14}C (mineral soil, humus layer, leaf litter layer, and total soil respiration) data. Results show that the model correctly simulates the impact of the Enriched Background Isotope Study {sup 14}C experimental treatments on soil respiration {Delta} {sup 14}C values for the different soil organic matter pools. Model results suggest that a two-pool root growth model correctly represents root carbon dynamics and inputs to the soil. The model fitting process and sensitivity analysis exposed uncertainty in our estimates of the fraction of mineral soil in the slow and passive pools, dissolved organic carbon flux out of the litter layer into the mineral soil, and mixing of the humus layer into the mineral soil layer.« less

ForCent Model Development and Testing using the Enriched Background Isotope Study (EBIS) Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parton, William; Hanson, Paul J; Swanston, Chris

The ForCent forest ecosystem model was developed by making major revisions to the DayCent model including: (1) adding a humus organic pool, (2) incorporating a detailed root growth model, and (3) including plant phenological growth patterns. Observed plant production and soil respiration data from 1993 to 2000 were used to demonstrate that the ForCent model could accurately simulate ecosystem carbon dynamics for the Oak Ridge National Laboratory deciduous forest. A comparison of ForCent versus observed soil pool 14C signature (? 14C) data from the Enriched Background Isotope Study 14C experiment (1999-2006) shows that the model correctly simulates the temporal dynamicsmore » of the 14C label as it moved from the surface litter and roots into the mineral soil organic matter pools. ForCent model validation was performed by comparing the observed Enriched Background Isotope Study experimental data with simulated live and dead root biomass ? 14C data, and with soil respiration ? 14C (mineral soil, humus layer, leaf litter layer, and total soil respiration) data. Results show that the model correctly simulates the impact of the Enriched Background Isotope Study 14C experimental treatments on soil respiration ? 14C values for the different soil organic matter pools. Model results suggest that a two-pool root growth model correctly represents root carbon dynamics and inputs to the soil. The model fitting process and sensitivity analysis exposed uncertainty in our estimates of the fraction of mineral soil in the slow and passive pools, dissolved organic carbon flux out of the litter layer into the mineral soil, and mixing of the humus layer into the mineral soil layer.« less

Chloride and organic chlorine in forest soils: storage, residence times, and influence of ecological conditions.

PubMed

Redon, Paul-Olivier; Abdelouas, Abdesselam; Bastviken, David; Cecchini, Sébastien; Nicolas, Manuel; Thiry, Yves

2011-09-01

Recent studies have shown that extensive chlorination of natural organic matter significantly affects chlorine (Cl) residence time in soils. This natural biogeochemical process must be considered when developing the conceptual models used as the basis for safety assessments regarding the potential health impacts of 36-chlorine released from present and planned radioactive waste disposal facilities. In this study, we surveyed 51 French forested areas to determine the variability in chlorine speciation and storage in soils. Concentrations of total chlorine (Cl(tot)) and organic chlorine (Cl(org)) were determined in litterfall, forest floor and mineral soil samples. Cl(org) constituted 11-100% of Cl(tot), with the highest concentrations being found in the humus layer (34-689 mg Cl(org) kg(-1)). In terms of areal storage (53 - 400 kg Cl(org) ha(-1)) the mineral soil dominated due to its greater thickness (40 cm). Cl(org) concentrations and estimated retention of organochlorine in the humus layer were correlated with Cl input, total Cl concentration, organic carbon content, soil pH and the dominant tree species. Cl(org) concentration in mineral soil was not significantly influenced by the studied environmental factors, however increasing Cl:C ratios with depth could indicate selective preservation of chlorinated organic molecules. Litterfall contributions of Cl were significant but generally minor compared to other fluxes and stocks. Assuming steady-state conditions, known annual wet deposition and measured inventories in soil, the theoretical average residence time calculated for total chlorine (inorganic (Cl(in)) and organic) was 5-fold higher than that estimated for Cl(in) alone. Consideration of the Cl(org) pool is therefore clearly important in studies of overall Cl cycling in terrestrial ecosystems.

A hydrological tracer study of water uptake depth in a Scots pine forest under two different water regimes.

PubMed

Plamboeck, A H; Grip, H; Nygren, U

1999-05-01

Little is known about the vertical distribution of water uptake by trees under different water supply regimes, the subject of this study, conducted in a Scots pine stand on sandy loam in northern Sweden. The objective was to determine the water uptake distribution in pines under two different water regimes, desiccation (no precipitation) and irrigation (2 mm day -1 in July and 1 mm day -1 in August), and to relate the uptake to water content, root and soil texture distributions. The natural 18 O gradient in soil water was exploited, in combination with two added tracers, 2 H at 10 cm and 3 H at 20 cm depth. Extraction of xylem sap and water from the soil profile then enabled evaluation of relative water uptake from four different soil depths (humus layer, 0-10, 10-25 and 25-55 cm) in each of two 50-m 2 plots per treatment. In addition, water content, root biomass and soil texture were determined. There were differences in vertical water uptake distribution between treatments. In July, the pines at the irrigated and desiccated plots took up 50% and 30%, respectively, of their water from the upper layers, down to 25 cm depth. In August, the pines on the irrigated plots took up a greater proportion of their water from layers below 25 cm deep than they did in July. In a linear regression, the mean hydraulic conductivity for each mineral soil horizon explained a large part of the variation in relative water uptake. No systematic variation in the residual water uptake correlated to the root distribution. It was therefore concluded that the distribution of water uptake by the pines at Åheden was not a function of root density in the mineral soil, but was largely determined by the unsaturated hydraulic conductivity.

New insights into the ground thermal regime of talus slopes with permafrost below the timberline

NASA Astrophysics Data System (ADS)

Schwindt, Daniel; Kneisel, Christof

2013-04-01

In the central Alps permafrost can be expected above 2400 m a.s.l., at altitudes where mean annual air temperatures are below -1° C. However, isolated permafrost occurrences are present in north-exposed talus slopes, far below the timberline, where mean annual air temperatures are positive. Driving factors are assumed to be a low income of solar radiation, a thick organic layer with high insulation capacities as well as the thermally induced chimney effect (Wakonigg, 1996). Investigated are three talus slopes with permafrost in the Swiss Alps that differ with regard to elevation level, talus material, humus characteristics and vegetation composition as well as the mean annual air temperatures. Aim is to achieve a deeper understanding of the factors determining the site-specific thermal regime, as well as the spatially limited and temporally highly variable permafrost occurrences in vegetated talus slopes. Focus is not solely on the question of why permafrost exists at these sites, but also why permafrost does not exist in the immediate surroundings. To detect the temporal variability and spatial heterogeneity of the permafrost occurrences, electrical resistivity tomography monitoring, seismic refraction tomography monitoring, and quasi-3D ERT were applied. To determine the ground thermal regime, air-, ground surface-, and humus temperatures, as well as temperatures within vents of the chimneys were recorded. Furthermore, humus characteristics (thickness, -temperature and -moisture) were mapped in permafrost-affected slope areas and in the immediate surroundings. To test the correlation between solar radiation, permafrost distribution, and humus/vegetation composition, digital elevation models were used to calculate the income of solar radiation. The areal extent of the permafrost bodies coincide precisely with slope sections where the organic layer is thickest, a consistent moss cover is present, and where temperatures at the transition between humus layer and talus material are lowest. The interaction of factors driving the ground thermal regime turned out to be more complex than assumed with differences between the investigated sites. Besides convective heat transport of the chimney effect, conductive heat flow within the humus layer strongly influences the ground thermal regime. Supercooling of the talus material in winter and autumn is aggravated by a high thermal conductivity of the organic material under frozen and wet conditions. The preservation of permafrost is favoured by the high insulation capacity of dry organic material in summer and by a prolonged zero-curtain period of up to 3 months - driven by high water-storage capacity of the organic material - that buffers the propagation of warm temperatures into the subsurface in spring. The income of solar radiation at the foot of the slope does not state a major driving factor for the occurrence of permafrost. Variability is low between areas with and without permafrost. In fact, differences were detected upslope, below the rock-walls, with summer-values being lowest in areas above the permafrost occurrences. It must be assumed that this affects the thermal circulation of the chimney effect during summer and favours the persistence of frozen ground in spatially limited slope areas.

Using atmospheric fallout to date organic horizon layers and quantify metal dynamics during decomposition

NASA Astrophysics Data System (ADS)

Kaste, James M.; Bostick, Benjamin C.; Heimsath, Arjun M.; Steinnes, Eiliv; Friedland, Andrew J.

2011-03-01

High concentrations of metals in organic matter can inhibit decomposition and limit nutrient availability in ecosystems, but the long-term fate of metals bound to forest litter is poorly understood. Controlled experiments indicate that during the first few years of litter decay, Al, Fe, Pb, and other metals that form stable complexes with organic matter are naturally enriched by several hundred percent as carbon is oxidized. The transformation of fresh litter to humus takes decades, however, such that current datasets describing the accumulation and release of metals in decomposing organic matter are timescale limited. Here we use atmospheric 210Pb to quantify the fate of metals in canopy-derived litter during burial and decay in coniferous forests in New England and Norway where decomposition rates are slow and physical soil mixing is minimal. We measure 210Pb inventories in the O horizon and mineral soil and calculate a 60-630 year timescale for the production of mobile organo-metallic colloids from the decomposition of fresh forest detritus. This production rate is slowest at our highest elevation (˜1000 m) and highest latitude sites (>63°N) where decomposition rates are expected to be low. We calculate soil layer ages by assuming a constant supply of atmospheric 210Pb and find that they are consistent with the distribution of geochemical tracers from weapons fallout, air pollution, and a direct 207Pb application at one site. By quantifying a gradient of organic matter ages with depth in the O horizon, we describe the accumulation and loss of metals in the soil profile as organic matter transforms from fresh litter to humus. While decomposition experiments predict that Al and Fe concentrations increase during the initial few years of decay, we show here that these metals continue to accumulate in humus for decades, and that enrichment occurs at a rate higher than can be explained by quantitative retention during decomposition alone. Acid extractable Al and Fe concentrations are higher in the humus layer of the O horizon than in the mineral soil immediately beneath this layer: it is therefore unlikely that physical soil mixing introduces significant Al and Fe to humus. This continuous enrichment of Al and Fe over time may best be explained by the recent suggestion that metals are mined from deeper horizons and brought into the O horizon via mycorrhizal plants. In sharp contrast to Al and Fe, we find that Mn concentrations in decomposing litter layers decrease exponentially with age, presumably because of leaching or rapid uptake, which may explain the low levels of acid extractable Mn in the mineral soil. This study quantifies how metals are enriched and lost in decomposing organic matter over a longer timescale than previous studies have been able to characterize. We also put new limits on the rate at which metals in litter become mobile organo-metallic complexes that can migrate to deeper soil horizons or surface waters.

Transect studies on pine litter organic matter: decomposition and chemical properties of upper soil layers in Polish forests

Treesearch

Alicja Breymeyer; Marek Degorski; David Reed

1998-01-01

The relationship between litter decomposition rate, some chemical properties of upper soil layers (iron, manganese, zinc, copper, lead, mercury, nickel, chrome in humus-mineral horizon-A), and litter (the same eight elements in needle litter fraction) in pine forests of Poland was studied. Heavy metal content in organic-mineral horizon of soils was highly correlated...

Disruption of root carbon transport into forest humus stimulates fungal opportunists at the expense of mycorrhizal fungi.

PubMed

Lindahl, Björn D; de Boer, Wietse; Finlay, Roger D

2010-07-01

Ectomycorrhizal fungi dominate the humus layers of boreal forests. They depend on carbohydrates that are translocated through roots, via fungal mycelium to microsites in the soil, wherein they forage for nutrients. Mycorrhizal fungi are therefore sensitive to disruptive disturbances that may restrict their carbon supply. By disrupting root connections, we induced a sudden decline in mycorrhizal mycelial abundance and studied the consequent effects on growth and activity of free living, saprotrophic fungi and bacteria in pine forest humus, using molecular community analyses in combination with enzyme activity measurements. Ectomycorrhizal fungi had decreased in abundance 14 days after root severing, but the abundance of certain free-living ascomycetes was three times higher within 5 days of the disturbance compared with undisturbed controls. Root disruption also increased laccase production by an order of magnitude and cellulase production by a factor of 5. In contrast, bacterial populations seemed little affected. The results indicate that access to an external carbon source enables mycorrhizal fungi to monopolise the humus, but disturbances may induce rapid growth of opportunistic saprotrophic fungi that presumably use the dying mycorrhizal mycelium. Studies of such functional shifts in fungal communities, induced by disturbance, may shed light on mechanisms behind nutrient retention and release in boreal forests. The results also highlight the fundamental problems associated with methods that study microbial processes in soil samples that have been isolated from living roots.

BOREAS HYD-6 Aircraft Gamma Ray Soil Moisture Data

NASA Technical Reports Server (NTRS)

Peck, Eugene L.; Hall, Forrest G. (Editor); Knapp, David E. (Editor); Carroll, Thomas; Smith, David E. (Technical Monitor)

2000-01-01

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-6 team collected several data sets related to the moisture content of soil and overlying humus layers. This data set contains percent soil moisture (by weight) (and/or water content if there is a moss/humus layer) measured from aircraft using a terrestrial gamma ray instrument. There are also data that indicate the location of the aircraft at the time it collected the terrestrial gamma ray data for the various flight lines and bins. The location information contains a list of coordinates that indicate the path of the aircraft for each bin. The data were collected during four time periods from September 1993 to September 1994 over the southern study area (SSA) and two time periods from February to August 1994 over the northern study area (NSA). The data are available in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884) or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

Long-term 15N tracking from biological N fixation across different plant and humus components of the boreal forest

NASA Astrophysics Data System (ADS)

Arroniz-Crespo, Maria; Jones, David L.; Zackrisson, Olle; Nilsson, Marie-Charlotte; DeLuca, Thomas H.

2014-05-01

Biological N2 fixation by cyanobacteria associated with feather mosses is an important cog in the nitrogen (N) cycle of boreal forests; still, our understanding of the turnover and fate of N fixed by this association remains greatly incomplete. The 15N signature of plants and soil serves as a powerful tool to explore N dynamics in forest ecosystems. In particular, in the present study we aimed to investigate the contribution of N2 fixation to δ15N signatures of plants and humus component of the boreal forest. Here we present results from a long-term (7 years) tacking of labelled 15N2 across the humus layer, seedlings of the tree species Pinus sylvestris, two common dwarf shrub species (Empetrum hermaphroditum and Vaccinium vitis-idaea) and the feather moss Pleurozium schreibery. The enriched experiment was conducted in 2005 in a natural boreal forest in northern Sweden. Two different treatments (10% 15N2 headspace enrichment and control) were setup in nine different plots (0.5 x 0.5 m) within the forest. We observed a significant reduction of δ15N signature of the 15N-enriched moss that could be explained by a growth dilution effect. Nevertheless, after 5 years since 15N2 enrichment some of the label 15N was still detected on the moss and in particular in the dead tissue. We could not detect a clear transfer of the labelled 15N2 from the moss-cyanobacteria system to other components of the ecosystem. However, we found consistence relationship through time between increments of δ15N signature of some of the forest components in plots which exhibited higher N fixation rates in the moss. In particular, changes in natural abundance δ15N that could be associated with N fixation were more apparent in the humus layer, the dwarf shrub Vaccinium vitis-idaea and the pine seedlings when comparing across plots and years.

Plant uptake/bioavailability of heavy metals from the contaminated soil after treatment with humus soil and hydroxyapatite.

PubMed

Misra, Virendra; Chaturvedi, Pranav Kumar

2007-10-01

Uptake /bioavailability study using the Indian mustard plant (Brassica juncea) was undertaken at the interval of 7, 14 and 21 days to test the immobilization of heavy metals from contaminated soil that were amended with humus soil and/or hydroxyapatite. For this, four sets consisting of non-humus soil + metals (Cd, Cr, Ni and Pb), humus soil + metals, non-humus and humus soil in the ratio of 1:3 + metals and non-humus soil: humus soil in the ratio of 1:3 + metals + 1% hydroxyapatite were prepared. The bioavailability of Pb, Cd, Cr and Ni in non-humus soil system was 58%, 67%, 65% and 63%, respectively in 7 days, more than 80% in 14 days and more than 90% in 21 days. Use of non-humus, humus soil in the ratio of 1:3 and addition of 1% hydroxyapatite decreased the bioavailability of lead around 21 to 22.5%, Cd 35 to 36%, Cr 25.5 to 26.9%, Ni 34 to 39% in 7, 14 and 21 days. Apart from this increase in the fresh weight of the plant was also noticed during the experiment. The data showed that addition of 1% hydroxyapatite in the non-humus-humus soil system caused the increase in the fresh weight around 90% in 7, 14 and 21 days as compared to plant grown in non-humus and metal soil system.

A European Humus Forms Reference Base

NASA Astrophysics Data System (ADS)

Zanella, A.; Englisch, M.; Ponge, J.-F.; Jabiol, B.; Sartori, G.; Gardi, C.

2012-04-01

From 2003 on, a panel of experts in humus and humus dynamics (Humus group) has been working about a standardisation and improvement of existing national humus classifications. Some important goals have been reached, in order to share data and experiences: a) definition of specific terms; b) description of 15 types of diagnostic horizons; c) of 10 basic humus forms references; d) subdivision of each main reference in 2-4 sub-unities; e) elaboration of a general European Humus Form Reference Base (http://hal-agroparistech.archives-ouvertes.fr/docs/00/56/17/95/PDF/Humus_Forms_ERB_31_01_2011.pdf); f) publication of the scientific significance of this base of classification as an article [A European morpho-functional classification of humus forms. Geoderma, 164 (3-4), 138-145]. The classification will be updated every 2 years and presently the Humus group is assessing biological (general: soil, vegetation, biome; specific: fungi, bacteria, pedofauna), physical (air temperature, rainfall) and chemical (pH, mineral elements, organic matter, quality and quantity of humic components…) factors which characterize basic humus forms and their varieties. The content of the new version of the classification is planned to be more "practical", like an ecological manual which lists associated humus forms and environmental data in the aim to contribute to a more precise environmental diagnosis of every analysed terrestrial and semiterrestrial European ecosystem. The Humus group is also involved in an endeavour to include humus forms in the World Reference Base for Soils (WRB-FAO) according to nomenclatural principles erected for soil profiles. Thirty basic references have been defined, complemented by a set of qualifiers (prefixes and suffixes), allowing to classify European humus forms and probably a large majority of humus forms known worldwide. The principles of the classification, the diagnostic horizons and humus forms main references are presented at the General Assembly of the European Geosciences Union with the aim to stimulate members' curiosity. Interested people are invited to test the classification system in various field areas and to collaborate with the Humus group. Critical observations and field data/impressions are welcome as every other suggestions which can help in elaborating the 2013 version of the European humus forms classification.

[Short-term effects of low intensity thinning simulated by gap on ground microclimate and soil nutrients of pure spruce plantation].

PubMed

Wang, Cheng; Pang, Xue-Yong; Bao, Wei-Kai

2010-03-01

Taking a dense spruce pure plantation as test object and simulating the formation of natural forest gap, this paper studied the effects of low intensity thinning by gap creation on the ground temperature, ground humidity, and nutrient contents in different soil layers of the plantation. In the first year of gap creation, the mean diurnal temperature in the gap across the growth season (May - September) increased, while the mean diurnal humidity decreased. The soil organic matter (SOM) and NH4(+) -N contents in O-horizon (humus layer) increased by 19.62% and 283.85%, and the dissolved organic carbon (DOC) and NO3(-) -N contents decreased by 77.86% and 23.60%, respectively. The SOM, total nitrogen (TN), and NO3(-) -N contents in 0-10 cm soil layer increased by 45.77%, 37.14%, and 75.11%, and the NH4(+) -N, DOC, and total phosphorus (TP) contents decreased by 48.56%, 33.33%, and 13.11%, respectively. All the results suggested that low intensity thinning by gap creation could rapidly improve the ground microclimate of the plantation, and consequently, promote the soil microbial activity and mineralization processes in O-horizon, the release of soil nutrients, and the restoration of soil fertility.

Exploring Soil Ecosystems.

ERIC Educational Resources Information Center

Finley, Deborah R.

1991-01-01

Describes a soil lab that can be performed with a minimum of equipment and time, utilizing a lawn, field, or woodlot. Students dig a 1-meter-deep pit and observe the litter and humus layers where most microbial and fungal decomposition occurs. Describes comparing different locations by pH level and concentration of potassium, phosphorous, and…

Humus and soil fertility

Treesearch

Kevin T. Smith

2010-01-01

Humus is a Latin word, meaning on or in the ground, but what is humus in the context of tree and landscape care? Is humus the same as soil organic matter? With the increased emphasis on biologically-based products for sustainable landscapes and tree care, the sources and quality of humus products have greatly increased in recent years.

Behaviour of 137Cs in forest humus detected across the territory of the Czech Republic.

PubMed

Škrkal, Jan; Pilátová, Helena; Rulík, Petr; Suchara, Ivan; Sucharová, Julie; Holá, Marie

2017-09-01

The activity concentration of 137 Cs in samples of coniferous forest humus collected across the territory of the Czech Republic in 1995 and 2005 was analysed, and it was found significantly correlated with the surface deposition caused by the Chernobyl accident. The effective (12.8 y) and environmental (22.3 y) half-lives of radiocaesium in humus were calculated and compared with those in spruce bark. The impact of important forest stand factors, that is, precipitation, content of organic matter, age of trees and pH, on the behaviour of 137 Cs in humus was studied. It was observed that humus samples with a higher proportion of organic matter, higher pH(H2O) and pH(CaCl2) contained higher amounts of 137 Cs. Conversely, with the age of trees, the activity concentration of 137 Cs in humus is decreasing. Higher precipitation and humus acidity decrease the reduction rate of the 137 Cs in humus. These stand factors increase bioavailability of 137 Cs in humus. The transfer and retention of available 137 Cs in biomass of organisms living in humus for a long time can satisfactorily explain the longer residence time of 137 Cs in humus affected by the studied factors. Copyright © 2017 Elsevier B.V. All rights reserved.

Stand age and fine root biomass, distribution and morphology in a Norway spruce chronosequence in southeast Norway.

PubMed

Børja, Isabella; De Wit, Heleen A; Steffenrem, Arne; Majdi, Hooshang

2008-05-01

We assessed the influence of stand age on fine root biomass and morphology of trees and understory vegetation in 10-, 30-, 60- and 120-year-old Norway spruce stands growing in sandy soil in southeast Norway. Fine root (< 1, 1-2 and 2-5 mm in diameter) biomass of trees and understory vegetation (< 2 mm in diameter) was sampled by soil coring to a depth of 60 cm. Fine root morphological characteristics, such as specific root length (SRL), root length density (RLD), root surface area (RSA), root tip number and branching frequency (per unit root length or mass), were determined based on digitized root data. Fine root biomass and morphological characteristics related to biomass (RLD and RSA) followed the same tendency with chronosequence and were significantly higher in the 30-year-old stand and lower in the 10-year-old stand than in the other stands. Among stands, mean fine root (< 2 mm) biomass ranged from 49 to 398 g m(-2), SLR from 13.4 to 19.8 m g(-1), RLD from 980 to 11,650 m m(-3) and RSA from 2.4 to 35.4 m(2) m(-3). Most fine root biomass of trees was concentrated in the upper 20 cm of the mineral soil and in the humus layer (0-5 cm) in all stands. Understory fine roots accounted for 67 and 25% of total fine root biomass in the 10- and 120-year-old stands, respectively. Stand age had no affect on root tip number or branching frequency, but both parameters changed with soil depth, with increasing number of root tips and decreasing branching frequency with increasing soil depth for root fractions < 2 mm in diameter. Specific (mass based) root tip number and branching density were highest for the finest roots (< 1 mm) in the humus layer. Season (spring or fall) had no effect on tree fine root biomass, but there was a small and significant increase in understory fine root biomass in fall relative to spring. All morphological characteristics showed strong seasonal variation, especially the finest root fraction, with consistently and significantly higher values in spring than in fall. We conclude that fine root biomass, especially in the finest fraction (< 1 mm in diameter), is strongly dependent on stand age. Among stands, carbon concentration in fine root biomass was highest in the 30-year-old stand, and appeared to be associated with the high tree and canopy density during the early stage of stand development. Values of RLD and RSA, morphological features indicative of stand nutrient-uptake efficiency, were higher in the 30-year-old stand than in the other stands.

Remote sensing of hydrologic variables in boreal areas

NASA Technical Reports Server (NTRS)

Peck, Eugene L.; Carroll, Thomas R.

1995-01-01

During Phase 2 airborne Gamma Radiation measurements were conducted over 48 BOREAS flight lines. Ground measurements of the soil moisture (SM) of the mineral soil and of the depth and water content (WC) of the moss/humus layer were collected for calibration of the flight lines. Special attention has been given to the flight lines over and near the primary tower sites in the southern study area (SSA): Old Black Spruce (OBS), Old Jack Pine, Old Aspen, and Young Aspen. Multiple ground surveys (September 1993; July, August, and September 1994) show the variation of the water content of the moss/humus layers and changes in the amount of standing water near the SSA, OBS tower during the period September 1993 to September 1994. All ground data, airborne estimates and locations of flight lines and ground sampling points have been submitted to BORIS (Boreas Information System). On 8-10 September 1994 exceptionally high values of cosmic radiation were observed by the airborne gamma radiation system over the SSA. Follow-up investigation has not determined the source of, or what caused, the high cosmic count rates.

Remote sensing of hydrologic variables in boreal areas, phase 2

NASA Technical Reports Server (NTRS)

Peck, Eugene L.; Carroll, Thomas R.

1995-01-01

During Phase 2 airborne Gamma Radiation measurements were conducted over 48 BOREAS (boreal ecosystem atmosphere study) flight lines. Ground measurements of the soil moisture (SM) of the mineral soil and the depth and water content (WC) of the moss/humus layer were collected for calibration of the flight lines. Special attention has been given to the flight lines over, and near, the primary tower sites in the southern study area (SSA); Old Black Spruce (OBS), Old Jack Pine, Old Aspen, and Young Aspen. Multiple ground surveys (September 1993, July, August, and September 1994) show the variation of the water content of the moss/humus layers and changes in the amount of standing water near the SSA OBS tower during the period September 1993 to September 1994. All ground data, airborne estimates and locations of flight lines and ground sampling points have been submitted to BORIS (BOREAS Information System). On 8-10 September 1994 exceptionally high values of cosmic radiation were observed by the airborne gamma radiation system over the SSA. Follow up investigation has not determined the source of, or what caused, the high cosmic count rates.

Changes in fungal communities along a boreal forest soil fertility gradient.

PubMed

Sterkenburg, Erica; Bahr, Adam; Brandström Durling, Mikael; Clemmensen, Karina E; Lindahl, Björn D

2015-09-01

Boreal forests harbour diverse fungal communities with decisive roles in decomposition and plant nutrition. Although changes in boreal plant communities along gradients in soil acidity and nitrogen (N) availability are well described, less is known about how fungal taxonomic and functional groups respond to soil fertility factors. We analysed fungal communities in humus and litter from 25 Swedish old-growth forests, ranging from N-rich Picea abies stands to acidic and N-poor Pinus sylvestris stands. 454-pyrosequencing of ITS2 amplicons was used to analyse community composition, and biomass was estimated by ergosterol analysis. Fungal community composition was significantly related to soil fertility at the levels of species, genera/orders and functional groups. Ascomycetes dominated in less fertile forests, whereas basidiomycetes increased in abundance in more fertile forests, both in litter and humus. The relative abundance of mycorrhizal fungi in the humus layer remained high even in the most fertile soils. Tolerance to acidity and nitrogen deficiency seems to be of greater importance than plant carbon (C) allocation patterns in determining responses of fungal communities to soil fertility, in old-growth boreal forests. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

[Soil humus differentiation and correlation with other soil biochemical properties in pure forests in semi-arid low-hilly area of Inner Mongolia, China].

PubMed

Zhang, Xiao-Xi; Liu, Zeng-Wen; Bing, Yuan-Hao; Zhu, Bo-Chao; Huang, Liang-Jia

2014-10-01

Whether the content and composition of soil humus in pure forest change due to its simple component of litter and specificity of single-species dominant community is a key problem for forest sustainable management. In this study, soils from 6 kind of pure forests in semi-arid low-hilly area of Inner Mongolia were collected and their humus and other biochemical properties were measured to investigate the differentiation of soil humus and the impact factors. The results showed that the soil of Picea asperata and Betula platyphylla pure forests had the highest contents of humus and better condensation degrees and stabilities, followed by that of Populus simonii, Larix principis-rupprechtii and Ulmus pumila pure forests, while the soil of Pinus tabuliformis pure forest had the lowest content of humus, condensation degree and stability. There were significant positive correlations between soil microorganism biomass, activity of phosphatase and the content and stability of soil humus. In contrast, the soil peroxidate, dehydrogenase activity and soil humus content showed significant negative correlations with each other. Furthermore, the enhancement of dehydrogenase activity might decrease the stability of humus. There were significant positive correlations between available N and the content and stability of soil humus, but total Cu, Zn and Fe had negative correlations with them, and total Cu and Fe might reduce the stability of humus as well. The particularity of pure forest environment and litter properties might be the key inducement to soil humus differentiation, thus reforming the pure forest through mixing with other tree species or planting understory vegetation would be the fundamental way to improve the soil humus composition and stability.

Electroosmotically enhanced drying of biomass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, S.; Law, S.E.

A laboratory system for experimentally characterizing electroosmotic dewatering of biomass has been developed. The system was used to investigate the dewatering at both constant voltage and constant current of two biomass materials, organic humus with peat and composted wastewater sludge (WWS). The moisture content of humus decreased to 22.5% from an initial value of 44.3% wet basis (wb) after 2 h 10 min of electroosmosis at 50 V across a 2.9-cm-thick bed, whereas that of sludge decreased to 54.5% from an initial value of 68.4% after 2 h 20 min at 40 V across the bed. The electrical energy requiredmore » to remove 1 kg of water by constant-voltage electroosmosis of humus varied from 23% to 61%, in the voltage range of 10--50 V, of the thermal energy required to change the same quantity of free water from liquid to vapor state. For WWS, the energy remained constant at a higher value of 88% over the 20--40-V range studied. The flowrate of liquid water out of the bed at constant voltage linearly increased with the applied electric field, and the electrical energy expended in the constant-current dewatering mode was seen to be a quadratic function of time as predicted by classical electrokinetic theory.« less

Soils of the Southwestern Part of the Pacific Coast of Russia

NASA Astrophysics Data System (ADS)

Kostenkov, N. M.; Zharikova, E. A.

2018-02-01

The diversity of soils in the southwestern part of the Pacific coast of Russia (Primorie region) is discussed. Overall, 17 soil types belonging to 8 soil orders have been described in this region, and their morphology and properties have been studied. The diversity of plant communities, geomorphic conditions, and parent materials and relatively mild (as compared with other parts of the Far East region of Russia) specify the great variability of soil cover patterns. Low sea terraces are occupied by various peat, organo-accumulative, and gley soils; poorly drained medium-high terraces are the areas of various dark-humus and darkhumus gleyed soils. Typical and gleyic dark-humus podbels, dark-humus, and dark-humus gleyed soils formed on the high sea terraces. Residual elevations are occupied by brown forest (burozemic) soils, including typical burozems, dark-humus burozems, and gleyic dark-humus burozems and by dark-humus podbels. Various alluvial, gleyic gray-humus, and mucky gley soils are developed on riverine plains. On general, darkhumus soils with the high (>10%) humus content predominate; the area of dark-humus podbels us estimated at about 20%, and the area of dark-humus burozems is about 12%. All the soils in this region are specified by increased acidity values. The exchangeable sodium content is often high in the upper soil horizons with maximum values (0.71-1.19 cmol(c)/kg) in the peat gleyzems, peaty dark-humus soils, mucky-gley soils, and eutrophic peat soils of sea terraces. The grouping of the soils with respect to their physicochemical and agrochemical properties is suggested.

Impact of shelterbelts of different age on the content of nitrates and phosphates in ground water

NASA Astrophysics Data System (ADS)

Jaskulska, Renata; Wojciech Szajdak, Lech

2010-05-01

The investigations were carried out in the Agroecological Landscape Park situated 40 km South-West of Poznań in the upper Obra River watershed, Poland. The arable land constitutes 70%, shelterbelts and small afforestations about 14% and meadows and pastures about 12%. Shelterbelts belong to very efficient biogeochemical barriers. They decrease the migration of chemical compounds between ecosystems. The direction of ground water flow was from the adjoining cultivated field towards shelterbelts. Two shelterbelts of different humus guantity in surface layer soils were investigated. The age and species composition of plant was taken under consideration. The first one is 160-year-old shelterbelt, where predominant species is Robinia pseudoacacia, Quercus rober and Alnus glutinosa and is characterized by a well-developed humus level. The other one is 14-year-old shelterbelt. It includes 13 species of trees (Quercus petrea, Larix deciduas, Pinus silvestri, Populus nigra, Sorbus aucuparia) and reveals a small amount of humus. The soils are minerals, grey-brown podzolic in surface layer soils compound from light loamy sands and weakly loamy sands. The contents of N-NO3-, P-PO4-3, were investigated in the ground water under shelterbelts and adjoining cultivated fields. In addition, cationic sorptive capacity, specific surface areas, TOC were determined in soils. The smallest concentrations of nitrates (3.35 mg×l-1) and phosphates (0.02 mg×l-1) were observed in ground water under the 160-year-old shelterbelt. The physicochemical properties of soils under 160-year-old shelterbelt: specific surface areas (20.3 m2×g-1), cationic sorptive capacity (24.8 cmol(+)×kg-1), TOC (4.3%) was higher than in 14-year-old shelterbelt and in adjoining cultivated fields. The results revealed, that the 160-year-old shelterbelt characterizing developed humus more effectively than 14-year-old shelterbelt decreases the amounts of chemical compounds in ground water and sufficiently fulfils the function such as biogeochemical barrier in agricultural landscape. This work was supported by a grant No. N N305 229535 founded by Polish Ministry of Education.

Cadmium contamination of wood ash and fire-treated coniferous humus: Effect on soil respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fritze, H.; Kapanen, A.; Vanhala, P.

Atmospheric acidic deposition is known to affect soil fertility and in many countries, liming has been used to counteract anthropogenic soil acidification in coniferous forest soils. Other measures used to improve the acid neutralization capacity of forest soils are wood ash application and prescribed burning. In both cases, ash is deposited on the forest floor, resulting in a pH increase in the humus layer. Currently, application of forests with wood ash is under discussion in Finland, since the naturally occurring cadmium of forest trees is concentrated into the wood ash which then contains between 4 and 20 {mu} g{sup {minus}1}more » of dry matter. Microbes are essential for maintaining soil fertility and plant growth because they play a fundamental role in nutrient availability. Soil respiration rate, which is an indicator of the microbially-mediated nutrient turnover rate, is decreased by addition of cadmium to the soil environment. In this paper we report on the effects of cadmium addition on the soil respiration rate of forest humus having received wood ash or fire treatments. The underlying objectives of this study were: (i) to determine the cadmium level which decreases the soil respiration of a Vaccinium site type forest humus to half of its original value (EC{sub 50}), (ii) to estimate how the forest treatments influence the EC{sub 50}, and (iii) to discuss the effect of Cd addition provided by wood ash on the nutrient mineralization rate. 17 refs., 2 figs., 2 tabs.« less

Potential bioavailability of mercury in humus-coated clay minerals.

PubMed

Zhu, Daiwen; Zhong, Huan

2015-10-01

It is well-known that both clay and organic matter in soils play a key role in mercury biogeochemistry, while their combined effect is less studied. In this study, kaolinite, vermiculite, and montmorillonite were coated or not with humus, and spiked with inorganic mercury (IHg) or methylmercury (MeHg). The potential bioavailability of mercury to plants or deposit-feeders was assessed by CaCl2 or bovine serum albumin (BSA) extraction. For uncoated clay, IHg or MeHg extraction was generally lower in montmorillonite, due to its greater number of functional groups. Humus coating increased partitioning of IHg (0.5%-13.7%) and MeHg (0.8%-52.9%) in clay, because clay-sorbed humus provided more strong binding sites for mercury. Furthermore, humus coating led to a decrease in IHg (3.0%-59.8% for CaCl2 and 2.1%-5.0% for BSA) and MeHg (8.9%-74.6% for CaCl2 and 0.5%-8.2% for BSA) extraction, due to strong binding between mercury and clay-sorbed humus. Among various humus-coated clay particles, mercury extraction by CaCl2 (mainly through cation exchange) was lowest in humus-coated vermiculite, explained by the strong binding between humus and vermiculite. The inhibitory effect of humus on mercury bioavailability was also evidenced by the negative relationship between mercury extraction by CaCl2 and mercury in the organo-complexed fraction. In contrast, extraction of mercury by BSA (principally through complexation) was lowest in humus-coated montmorillonite. This was because BSA itself could be extensively sorbed onto montmorillonite. Results suggested that humus-coated clay could substantially decrease the potential bioavailability of mercury in soils, which should be considered when assessing risk in mercury-contaminated soils. Copyright © 2015. Published by Elsevier B.V.

Biologically Active Organic Matter in Soils of European Russia

NASA Astrophysics Data System (ADS)

Semenov, V. M.; Kogut, B. M.; Zinyakova, N. B.; Masyutenko, N. P.; Malyukova, L. S.; Lebedeva, T. N.; Tulina, A. S.

2018-04-01

Experimental and literature data on the contents and stocks of active organic matter in 200 soil samples from the forest-tundra, southern-taiga, deciduous-forest, forest-steppe, dry-steppe, semidesert, and subtropical zones have been generalized. Natural lands, agrocenoses, treatments of long-term field experiments (bare fallow, unfertilized and fertilized crop rotations, perennial plantations), and different layers of soil profile are presented. Sphagnum peat and humus-peat soil in the tundra and forest-tundra zones are characterized by a very high content of active organic matter (300-600 mg C/100 g). Among the zonal soils, the content of active organic matter increases from the medium (75-150 mg C/100 g) to the high (150-300 mg C/100 g) level when going from soddy-podzolic soil to gray forest and dark-gray forest soils and then to leached chernozem. In the series from typical chernozem to ordinary and southern chernozem and chestnut and brown semidesert soils, a decrease in the content of active organic matter to the low (35-75 mg C/100 g) and very low (<35 mg C/100 g) levels is observed. Acid brown forest soil in the subtropical zone is characterized by a medium supply with active organic matter. Most arable soils are mainly characterized by low or very low contents of active organic matter. In the upper layers of soils, active organic matter makes up 1.2-11.1% of total Corg. The profile distribution of active organic matter in the studied soils coincides with that of Corg: their contents appreciably decrease with depth, except for brown semidesert soil. The stocks of active organic matter vary from 0.4 to 5.4 t/ha in the layer of 0-20 cm and from 1.0 to 12.4/ha in the layer of 0-50 cm of different soil types.

Humus: latent phase and reality.

PubMed

Pennazio, Sergio

2012-01-01

The evolution of the concept of humus was in large part dependent on the development of the modern agriculture. This concept derived from the very old practice of manuring and, after a long period of empirical application, was first theorised by Albrecht Thaer, who recognised the organic and inorganic content as the nutritional elements of humus. The role of humus as nutrient was challenged by Carl Sprengel and Justus Liebig, who opposed successfully the mineral theory to the theory of humus. The research in the property of humus, however, continued thanks to agronomists and agricultural chemists during a period in which the mineral theory was consolidated by the first experiments of the hydroponic cultures performed by Julius Sachs and Wilhelm Knop, but several outstanding chemists and microbiologists continued the work initiated by Thaer, giving humus full physicochemical identity and function. In this context shone the figure of Selman Abraham Waksman, whose work was of fundamental importance to the subsequent research in humus, which is still in progress.

The influence of different types of grassland on soil quality in upland areas of Czech Republic.

PubMed

Sarapatka, B; Cizkova, S

2014-05-01

The diversity of grassland in upland areas of Czech Republic was studied on selected soil characteristics of these biotopes. In the first phase, 44 soil characteristics were studied and mutual correlations were found between many of them. In the following phase characteristics were chosen which correlated most with other soil characteristics and, at the same time, were easy to evaluate in practise. A great number of correlations were also evidenced between many soil characteristics and the content of humus and nitrogen, which are closely linked to organic matter in soil. In studying these characteristics on selected areas with different types of grassland and consequential cluster analysis and further evaluation, the grassland plots were divided into three groups, from newly established vegetation to species-rich communities. Non-parametric analysis was carried out on the results and a statistically significant difference was proved between the species rich and poorvegetation and carbon and nitrogen content of the soil. Slightly different humus quality (higher amount of HA) was also found under richer vegetation. These results show that at 0-20 cm layer, 58.9 tonnes of carbon ha⁻¹ was measured under species-poor pastureland and 106.1 tonnes of carbon ha under species-rich vegetation. The results showed that besides supporting species diversity, the described quality change can also be important for carbon sequestration. The difference of about 40-50 tonnes of carbon ha and converting 10% of grassland in the Czech Republic to species-rich vegetation would mean sequestration of about 3.9 Mt carbon. If only agroenvironmentally subsidized areas are converted, carbon sequestration in such vegetation could amountto 1.7 Mt.

The sources and composition of humus in some soils of West Antarctica

NASA Astrophysics Data System (ADS)

Abakumov, E. V.

2010-05-01

Original data on humus-forming substances and their elemental and biochemical compositions in Antarctic soils are discussed. Mosses, lichens, algae, remains of higher vascular plants, and penguin guano of two types differ considerably in their chemical compositions. This leads to significant differences in the formation of humic substances in plant materials themselves in the course of their transformation. However, no significant differences in the composition of humus in the fine earth of soils developing under different humus-forming materials have been revealed, which may be related to the extremely low rates of humification. Significant differences between the soils of Antarctic landscapes proper and the soils of the Subantarctic King George Island are only observed in the humus enrichment with nitrogen. The soils of Antarctica are low-humus soils with the humate-fulvate or fulvate types of humus.

[Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

PubMed

Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

2015-08-01

In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

Effect of the chemical composition of green manure crops on humus formation in a Soddy-Podzolic soil

NASA Astrophysics Data System (ADS)

Tripolskaja, L.; Romanovskaja, D.; Slepetiene, A.; Razukas, A.; Sidlauskas, G.

2014-04-01

The effects of different types of green manure ( Trifolium pratense L., Dactylis glomerata L., and Secale cereale L.) and the time of its input into the soil (autumn and spring) on the contents of humus and labile humus substances in a soddy-podzolic soil and the relationship between the formation of humus and the chemical composition of the applied biomass were studied. Green manure had a positive effect on the accumulation of humus in the soil. When the plants were plowed into the soil in the fall, the amount of humus formed in the soil in the first year was 0.1% higher in comparison with the spring application of green manure. The most active synthesis of new humus substances took place upon the following properties of the plant biomass: C: N = 15-25, the cellulose content of 20-28%, and the lignin content of 14-17%. The highest amount of labile humus substances was formed during the decomposition of the biomass with the C: N ratio above 20, the cellulose content of 19-20%, and the lignin content of 14-16%.

[Analysis of soil humus and components after 26 years' fertilization by infrared spectroscopy method].

PubMed

Zhang, Yu-Lan; Sun, Cai-Xia; Chen, Zhen-Hua; Li, Dong-Po; Liu, Xing-Bin; Chen, Li-Jun; Wu, Zhi-Jie; Du, Jian-Xiong

2010-05-01

The infrared spectrum was used to discuss structure change of soil humus and components of chemical groups in soil humic acids (HA) and fulvic acids (FA) isolated from soils in different fertilization treatment after 26 year's fertilization. The result indicated that using the infrared spectroscopy method for the determination of humus, humus fractions (HA and FA) and their structure is feasible. Fertilization affected the structure and content of soil humus and aromatization degree. After 26 years' fertilization, the infrared spectrum shapes with different treatments are similar, but the characteristic peak intensity is obviously different, which reflects the effects of different fertilization treatments on the structure and amounts of soil humus or functional groups. Compared with no fertilization, little molecule saccharides decreased and aryl-groups increased under application of inorganic fertilizer or combined application of organic and chemical fertilizer. The effect was greater in Treatment NPK and M+NPK than in Treatment M1 N and M2 N. Organic and NPK fertilizer increased the development of soil and increased soil quality to a certain extent. Results showed that organic fertilization increased aromatization degree of soil humus and humus fractions distinctly. The authors could estimate soil humus evolvement of different fertilization with infrared spectroscopy.

Burial of downed deadwood is strongly affected by log attributes, forest ground vegetation, edaphic conditions, and climate zones

Treesearch

Jogeir N. Stokland; Christopher W. Woodall; Jonas Fridman; Göran Ståhl

2016-01-01

Deadwood can represent a substantial portion of forest ecosystem carbon stocks and is often reported following good practice guidance associated with national greenhouse gas inventories. In high-latitude forest ecosystems, a substantial proportion of downed deadwood is overgrown by ground vegetation and buried in the humus layer. Such burial obfuscates the important...

An empirical assessment of forest floor carbon stock components across the United States

Treesearch

Christopher W. Woodall; Charles H. Perry; James A. Westfall

2012-01-01

Despite its prevalent reporting in regional/national greenhouse gas inventories (NGHGI), forest floor (FF) carbon (C) stocks (including litter, humus, and fine woody debris [FWD]) have not been empirically measured using a consistent approach across forests of the US. The goal of this study was to use the first national field inventory of litter and humic layer depths...

Fuel loadings in southwestern ecosystems of the United States

Treesearch

Stephen S. Sackett; Sally M Haase

1996-01-01

Natural forest fuel loadings cause extreme fire behavior during dry, windy weather experienced during most fire seasons in the Southwest. Fire severity is also exacerbated from burning heavy fuels, including heavy humus layers on the forest floor. Ponderosa pine and mixed conifer stands possess more than 21.7 and 44.1 tons per acre of total forest floor fuel,...

Manganese availability is negatively associated with carbon storage in northern coniferous forest humus layers.

PubMed

Stendahl, Johan; Berg, Björn; Lindahl, Björn D

2017-11-14

Carbon sequestration below ground depends on organic matter input and decomposition, but regulatory bottlenecks remain unclear. The relative importance of plant production, climate and edaphic factors has to be elucidated to better predict carbon storage in forests. In Swedish forest soil inventory data from across the entire boreal latitudinal range (n = 2378), the concentration of exchangeable manganese was singled out as the strongest predictor (R 2  = 0.26) of carbon storage in the extensive organic horizon (mor layer), which accounts for one third of the total below ground carbon. In comparison, established ecosystem models applied on the same data have failed to predict carbon stocks (R 2  < 0.05), and in our study manganese availability overshadowed both litter production and climatic factors. We also identified exchangeable potassium as an additional strong predictor, however strongly correlated with manganese. The negative correlation between manganese and carbon highlights the importance of Mn-peroxidases in oxidative decomposition of recalcitrant organic matter. The results support the idea that the fungus-driven decomposition could be a critical factor regulating humus carbon accumulation in boreal forests, as Mn-peroxidases are specifically produced by basidiomycetes.

Humus depths under cut and uncut northern hardwood forests

Treesearch

George Hart

1960-01-01

Harvesting timber on lands devoted primarily to watershed management may alter, for better or worse, many features of a forested watershed. One such feature is forest humus. The beneficial role of forest humus in watershed management is widely recognized. A protective mantle of humus serves to cushion the impact of rain, to impede surface runoff, to restrict soil...

Approach of regionalisation c-stocks in forest soils on a national level

NASA Astrophysics Data System (ADS)

Wellbrock, Nicole; Höhle, Juliane; Dühnelt, Petra; Holzhausen, Marieanna

2010-05-01

Introduction In December 2006, the German government decided to manage forests as carbon sinks to reduce greenhouse gas emissions in accordance with Article 3.4 of the Kyoto Protocol. The National Forest Monitoring data contribute to the fulfilment of these reporting commitments. In Germany, National Forest Monitoring includes the systematical extensive National Soil Condition Survey (BZE) and the detailed case studies (Level-II) which determine the processes within forests. This complex monitoring system is appropriate to Germany's greenhouse gas reporting (THG 2008 to 2012). The representative BZE plots can be used to obtain regional data for the National Carbon Stock Inventory. Here, an approach adopting a combination of geostatistics and regression analysis is preferred. The difficulty of showing the statistical significance of expected small changes while carbon stocks are generally high is one of the major challenges in carbon stock monitoring. However, through intensive preparation and cooperation with the forestry authorities of each federal state, the errors uncured in determining changes in carbon stocks in forest soils, which must be stipulated in greenhouse gas monitoring, could be minimised. In contrast to the detailed soil case studies, in which essentially the sources of error occur repeatedly in carbon stock change calculations, the BZE data can be stratified to form plots with homogenous properties, thereby reducing the standard error of estimate. Subsequently, the results of the stratification are projected across Germany, the reporting unit for greenhouse gas monitoring. National Forest Monitoring The BZE represents a national, systematic sampling inventory of the condition of forest soils. The first BZE inventory (BZE I: 1987 to 1993) was carried out on a systematic 8 x 8 km grid on the same sampling plots adopted in the Forest Condition Survey (WZE). In some areas the network of sampling plots involves 1900 grid points. The first BZE I survey was repeated after 15 years, between 2006 and 2008, by the national and the state authorities in cooperation. Afterwards, extensive laboratory and statistical analyses were conducted. Necessary parameters are listed in table 1. Upscaling approach There are different approaches for presenting extensive carbon stock data (Baritz et al., 2006). The availability of georeference plots means one can merge the point data with map data. In Germany, an approach was tested that used homogenous soil areas und plot-information from the national soil inventory. For every soil area c-stocks were regionalised. Only information form BZE-plots were involved which were characteristic for the soil area. The indicators were soil type and substrate class. For every soil area the forest areas were taken in account to calculate c-stock per forest area. The sum of every c-stock per soil area is the c-stock in forest soils of Germany. Tab.1: List of parameters for the carbon inventory (BZE II) Components Parameters Point level Field sampling Width of depth classes, Fine roots, humus (< 2 cm), dry bulk density, stone content, area of humus layer sampled, height a.s.l., litterfall, deadwood (from 10 cm) Analysis C content, fine soil fraction, weight of humus layer, Carbon stock calculations Carbon stock Regional Level Plot Soil type, parent material, vegetation type or forest Regionalisation Soil and land use maps, statistical models, ecological regions, digital elevation models, climate regions

Improvement of activated sludge dewaterability by humus soil induced bioflocculation.

PubMed

Choi, Young-Gyun; Kim, Seong-Hong; Kim, Hee-Jun; Kim, Gyu Dong; Chung, Tai-Hak

2004-01-01

Effects of humus soil particles on the dewaterability of activated sludge were investigated. Cations leaching increased proportionally with the dosage of humus soil, and the leaching was not significant after 2 h. Divalent cations, Ca2+ and Mg2+, leaching from the humus soil played an important role in improving dewaterability of the biological sludge. On the contrary, dewaterability was not affected or slightly deteriorated by the monovalent cations, K+ and Na+ leached from the humus soil. Improvement in dewaterability of the sludge by addition of humus soil was higher than that of equivalent cations mixture. It seemed that the decrease of supracolloidal bio-particles (1 to 100 microm in diameter) resulted in diminishing of the blinding effect on cake and filter medium. SRF (specific resistance to filtration) of the humus soil added sludge varied in parallel with the M/D (monovalent to divalent cation) ratio, and the M/D ratio could be utilized as a useful tool for evaluation of the sludge dewatering characteristics. Long-term effects of humus soil on the improvement of activated sludge dewaterability were clearly identified by continuous operation results of a bench-scale MLE (Modified Ludzack Ettinger) system combined with a humus soil contactor. On the other hand, dewaterability of the control sludge was only slightly improved by a decrease in M/D ratio of the wastewater influent.

Yarding-method and slash-treatment effects on compaction, humus, and variation in plantation soils.

Treesearch

Don Minore; Howard G. Weatherly

1988-01-01

Soil penetration-resistance and soil-humus frequency were measured on 86 progeny-test plantations in southwestern Oregon to determine the effects of yarding method and slash treatment on soil compaction and humus, and a disturbance index was calculated for each plantation. Compaction and humus loss were more severe on tractor-yarded, machine-piled plantations than on...

The role of forest humus in watershed management in New England

Treesearch

G. R., Jr. Trimble; Howard W. Lull

1956-01-01

Forest humus is one of the most interesting components of the forest environment. Its surface serves as a depository for leaf fall and needle fall, with successive depths marking stages of transmutation from the freshly fallen to the decomposed. And humus is responsive: humus type and depth are indicators of forest treatment and, to some extent, of site quality....

Prairies Water Management on Corps Lands

DTIC Science & Technology

2009-02-01

less influence (Whisenant 1999). The soil organic matter content reaches equilibrium between humus formation (favored by high inputs of residues...and humus loss (favored by moist soil and high temperatures). Waterlogged soils with anaerobic conditions have a slow decomposition rate that...wet environment, soils tend to have low humus content, while in a cold environment soils have higher humus content. This equilibrium remains

Comment on "Fire-derived charcoal causes loss of forest humus".

PubMed

Lehmann, Johannes; Sohi, Saran

2008-09-05

Wardle et al. (Brevia, 2 May 2008, p. 629) reported that fire-derived charcoal can promote loss of forest humus and belowground carbon (C). However, C loss from charcoal-humus mixtures can be explained not only by accelerated loss of humus but also by loss of charcoal. It is also unclear whether such loss is related to mineralization to carbon dioxide or to physical export.

[Microbial community and its activities in canopy- and understory humus of two montane forest types in Ailao Mountains, Northwest China].

PubMed

Liu, Yong-jie; Liu, Wen-yao; Chen, Lin; Zhang, Han-bo; Wang, Gao-sheng

2010-09-01

Mid-montane moist evergreen broadleaved forest (MMF) and top-montane dwarf mossy forest (DMF) are the two major natural forest types in subtropical mountainous area of Ailao Mountains, Northwest China. In this paper, a comparative study was made on the microbial composition, quantity, biochemical activity, metabolic activity, and their seasonal dynamics in the canopy- and understory humus of the two forest types. The composition, quantity, and metabolic activity of the microbes in the canopy humus of dominant tree species in MMF and DMF were also analyzed. In the canopy humus of the two forest types, the amounts of fungi and actinomycetes, microbial biomass C and N, and intensities of nitrogen fixation and cellulose decomposition were significantly higher than those in understory humus. Meanwhile, the amount of cellulose-decomposing microbes (ACDM), cellulose decomposition intensity, microbial biomass C and N, and metabolic activity in the canopy humus of MMF were significantly higher than those of DMF. The amounts of bacteria, fungi, and aerobic nitrogen-fixing bacteria (ANFB) and the metabolic activity in the canopy humus of MMF and DMF were significantly higher in wet season than in dry season, while a contradictory trend was observed on the amount of actinomycetes. No significant difference was observed on the amount of ACDM between wet season and dry season. For the two forest types, the amounts of microbes and their biochemical activities in canopy humus had a larger seasonal variation range than those in understory humus. There was a significant difference in the amounts of the microbes in canopy humus among the dominant tree species in MMF and DMF, especially in wet season. The microbes in canopy humus played important roles in maintaining the biodiversity of epiphytes in the canopy, and in supplying the needed nutrients for the vigorous growth of the epiphytes.

Comparison of humus and till as prospecting material in areas of thick overburden and multiple ice-flow events: An example from northeastern New Brunswick

USGS Publications Warehouse

Broster, Bruce E.; Dickson, M.L.; Parkhill, M.A.

2009-01-01

Thirty-nine elements in humus and till matrix were compared at 109 sites overlying Ag-As-Cu-Mo-Pb-Zn mineralized occurrences in northeastern New Brunswick to assess humus for anomaly identification. Humus element concentrations were not consistently correlative with maximum or minimum concentrations found in the underlying till or bedrock. The humus demonstrated significantly higher mean elemental concentrations than the till for six specific elements: 9 times greater for Mn, 6 times greater for Cd, 5 times greater for Ag and Pb, 3 times greater for Hg, and double the concentration of Zn. Spatial dispersal patterns for these elements were much larger for humus content than that exhibited by the till matrix analysis, but did not delineate a point source. For elements in till, the highest concentrations were commonly found directly overlying the underlying mineralized bedrock source or within one km down-glacier of the source. The complexity of the humus geochemical patterns is attributed to the effects of post-glacial biogenic, down-slope hydrodynamic and solifluction modification of dispersed mineralization in the underlying till, and the greater capacity of humus to adsorb cations and form complexes with some elements, relative to the till matrix. Humus sampling in areas of glaciated terrain is considered to be mostly valuable for reconnaissance exploration as elements can be spatially dispersed over a much larger area than that found in the till or underlying bedrock. ?? 2009 Elsevier B.V. All rights reserved.

Layer of organic pine forest soil on top of chlorophenol-contaminated mineral soil enhances contaminant degradation.

PubMed

Sinkkonen, Aki; Kauppi, Sari; Simpanen, Suvi; Rantalainen, Anna-Lea; Strömmer, Rauni; Romantschuk, Martin

2013-03-01

Chlorophenols, like many other synthetic compounds, are persistent problem in industrial areas. These compounds are easily degraded in certain natural environments where the top soil is organic. Some studies suggest that mineral soil contaminated with organic compounds is rapidly remediated if it is mixed with organic soil. We hypothesized that organic soil with a high degradation capacity even on top of the contaminated mineral soil enhances degradation of recalcitrant chlorophenols in the mineral soil below. We first compared chlorophenol degradation in different soils by spiking pristine and pentachlorophenol-contaminated soils with 2,4,6-trichlorophenol in 10-L buckets. In other experiments, we covered contaminated mineral soil with organic pine forest soil. We also monitored in situ degradation on an old sawmill site where mineral soil was either left intact or covered with organic pine forest soil. 2,4,6-Trichlorophenol was rapidly degraded in organic pine forest soil, but the degradation was slower in other soils. If a thin layer of the pine forest humus was added on top of mineral sawmill soil, the original chlorophenol concentrations (high, ca. 70 μg g(-1), or moderate, ca. 20 μg g(-1)) in sawmill soil decreased by >40 % in 24 days. No degradation was noticed if the mineral soil was kept bare or if the covering humus soil layer was sterilized beforehand. Our results suggest that covering mineral soil with an organic soil layer is an efficient way to remediate recalcitrant chlorophenol contamination in mineral soils. The results of the field experiment are promising.

Microrelief and vegetation as the factors of spatial redistribution of nutrients in the soils of forest ecosystems

NASA Astrophysics Data System (ADS)

Chernitsova, Olga; Krechetov, Pavel

2017-04-01

The study is aimed at the identifying factors and mechanisms controlling the redistribution of nutrients in the profile of sod-podzolic soils (Umbric Albeluvisols Abruptic in WRB, 2006). The data of chemical analyzes of soil samples of soddy-pale-podzolic soils under mixed coniferous-deciduous forests, picked from the genetic horizons of 28 soil profiles up to the depth of 120-150 cm in the key area with a polygonal-block microrelief (58.39°N, 56.52°E) were used. Soil profiles were placed at the key area considering vegetation and microrelief. Samples were analyzed for humus content, available forms of N, P, K, Ca, Mg and soil texture. Published data on the capacity and the structure of biogeochemical cycling in forest phytocenoses of different ages in the southern taiga were summarized. Field sketches were used for the construction of the digital elevation model of the key area and for plotting the vegetation map showing the crowns' projections of trees and shrubs of different species. Using spatial interpolation in GIS, series of schematic maps were created that characterize the depth of the lower boundary of genetic horizons and their thickness, as well as the texture of the different soil horizons, humus content and distribution of nutrients at different depths. These schematic maps were analyzed for patterns of radial and lateral differentiation of all examined features. Pronounced textural differentiation of soils of micro-elevations and poor textural differentiation of soil of micro-depressions are revealed. It is shown that in the soils with the positions from micro-elevations through flat surfaces to micro-depressions the humus content in the upper layers (horizon A) increases 1.6-1.7 times, the content of nitrogen ‒ 1.4-1.5, phosphorus ‒ 2.6 8.4, calcium and magnesium cations ‒ 1.8-2.9 times. This differentiation in nutrients' content is coming along with the settlement of more demanding to soil fertility plants in micro-depressions. Also the bimodal distribution of the available forms of potassium, phosphorus, calcium, magnesium in the soil profile was revealed. The first maximum of nutrients content is detected in the humus-accumulative horizon A, the second - in the illuvial horizon Bt. The eluvial horizons EL are characterized by the minimum values. Considering the thickness of soil horizons, supplies of available forms of phosphorus, potassium, calcium and magnesium were estimated, which are 1.5-2.5 times higher in deeper soil horizons than in the upper ones. The complex ecological and geochemical structure of forest ecosystems is regulated by both the lateral additional supply of mobile chemical compounds by the surface and subsurface runoff, including melted snow water, as well as the peculiarities of biogeochemical cycling (the age of the forest, the penetration depth of suction roots of various species of trees, the chemical composition of the litter).

Protective effect of humus extract against Trypanosoma brucei infection in mice.

PubMed

Kodama, Hiroshi; Denso; Okazaki, Fumi; Ishida, Saeko

2008-11-01

Humic substances are formed during the decomposition of organic matter in humus, and are found in many natural environments in which organic materials and microorganisms are present. Oral administration of humus extract to mice successfully induced effective protection against experimental challenge by the two subspecies, Trypanosoma brucei brucei and T. brucei gambiense. Mortality was most reduced among mice who received a 3% humus extract for 21 days in drinking water ad libitum. Spleen cells from humus-administered mice exhibited significant non-specific cytotoxic activity against L1210 mouse leukemia target cells. Also, spleen cells produced significantly higher amounts of Interferon-gamma when stimulated in vitro with Concanavalin A than cells from normal controls. These results clearly show that administration to mice of humus extract induced effective resistance against Trypanosoma infection. Enhancement of the innate immune system may be involved in host defense against trypanosomiasis.

Integrated Assessment of Hadley Centre (HadCM2) Climate Change Projections on Agricultural Productivity and Irrigation Water Supply in the Conterminous United States.I. Climate change scenarios and impacts on irrigation water supply simulated with the HUMUS model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenberg, Norman J.; Brown, Robert A.; Izaurralde, R Cesar C.

This paper describes methodology and results of a study by researchers at PNNL contributing to the water sector study of the U.S. National Assessment of Climate Change. The vulnerability of water resources in the conterminous U.S. to climate change in 10-y periods centered on 2030 and 2095--as projected by the HadCM2 general circulation model--was modeled with HUMUS (Hydrologic Unit Model of the U.S.). HUMUS consists of a GIS that provides data on soils, land use and climate to drive the hydrology model Soil Water Assessment Tool (SWAT). The modeling was done at the scale of the 2101 8-digit USGS hydrologicmore » unit areas (HUA). Results are aggregated to the 4-digit and 2-digit (Major Water Resource Region, MWRR) scales for various purposes. Daily records of temperature and precipitation for 1961-1990 provided the baseline climate. Water yields (WY)--sum of surface and subsurface runoff--increases from the baseline period over most of the U.S. in 2030 and 2095. In 2030, WY increases in the western US and decreases in the central and southeast regions. Notably, WY increases by 139 mm from baseline in the Pacific NW. Decreased WY is projected for the Lower Mississippi and Texas Gulf basins, driven by higher temperatures and reduced precipitation. The HadCM2 2095 scenario projects a climate significantly wetter than baseline, resulting in WY increases of 38%. WY increases are projected throughout the eastern U.S. WY also increases in the western U.S. Climate change also affects the seasonality of the hydrologic cycle. Early snowmelt is induced in western basins, leading to dramatically increased WYs in late winter and early spring. The simulations were run at current (365 ppm) and elevated (560 ppm) atmospheric CO2 concentrations to account for the potential impacts of the CO2-fertilization effect. The effects of climate change scenario were considerably greater than those due to elevated CO2 but the latter, overall, decreased losses and augmented increases in water yield.« less

Evaluation of organic carbon stocks and CO2 fluxes in grasslands of Western Transbaikalia

NASA Astrophysics Data System (ADS)

Lavrentyeva, I. N.; Merkusheva, M. G.; Ubugunov, L. L.

2017-04-01

The stocks of organic carbon and mean rates of the CO2 emission during the growing season (May-September) and the entire year were estimated in a sequence of grass ecosystems along the transect encompassing chestnut and meadow-chestnut steppe soils, marsh and meadow alluvial soils, and a haloxerophytic community on a typical solonchak. The total stocks of organic carbon comprised 6.17-9.70 kg C/m2 in steppe, 7.41-10.04 kg C/m2 in floodplain, and 4.74 kg C/m2 in haloxerophytic ecosystems. The portion of humus carbon in the upper 50-cm-thick soil layer comprised 79-92% of the total carbon stock. The mean daily CO2 emission (C-CO2/(m2 day)) from alluvial soils was moderate (3.3-4.9) or low (1.5-2.5). The dependence of the CO2 emission on the moistening of steppe soils, temperature of alluvial soils, and temperature and moistening of solonchak was revealed. In comparison with the CO2 emission from the zonal chestnut soil, its mean values during the growing season and the entire year were 1.2 times higher for the meadowchestnut soil, 3.3 times higher for the marsh alluvial soil, 2.3 times higher for the meadow alluvial soil, and 1.7 times higher for the solonchak. The portion of the CO2 emission beyond the growing season in the mean annual emission averaged 19.8-24.2% and depended on the type of grass ecosystem and on weather conditions of particular years. The sink of carbon in the grass ecosystems exceeded carbon emission, especially in the steppe ecosystems.

Enhanced biodegradation of petroleum hydrocarbons in the mycorrhizosphere of sub-boreal forest soils.

PubMed

Robertson, Susan J; Kennedy, Nabla M; Massicotte, Hugues B; Rutherford, P Michael

2010-08-01

Petroleum hydrocarbon (PHC) contamination is becoming more common in boreal forest soils. However, linkages between PHC biodegradation and microbial community dynamics in the mycorrhizosphere of boreal forest soils are poorly understood. Seedlings (lodgepole pine, paper birch, lingonberry) were established in reconstructed soil systems, consisting of an organic layer (mor humus, coarse woody debris, or previously oil-contaminated mor humus) overlying mineral (Ae, Bf) horizons. Light crude oil was applied to the soil surface after 4 months; systems were destructively sampled at 1 and 16 weeks following treatment. Soil concentrations of four PHC fractions were determined using acetone-hexane extraction followed by gas chromatography - flame ionization detection analysis. Genotypic profiles of root-associated bacterial communities were generated using length heterogeneity-PCR of 16S rDNA. Most plant-soil treatments showed significant loss in the smaller fraction PHCs indicating an inherent capacity for biodegradation. Concentrations of total PHCs declined significantly only in planted (pine-woody debris and birch-humus) systems (averaging 59% and 82% loss between 1 and 16 weeks respectively), reinforcing the importance of the mycorrhizosphere for enhancing microbial catabolism. Bacterial community structure was correlated more with mycorrhizosphere type and complexity than with PHC contamination. However, results suggest that communities in PHC-contaminated and pristine soils may become distinct over time. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Remote sensing of hydrologic variables in boreal areas, phase 1

NASA Technical Reports Server (NTRS)

Peck, Eugene L.; Carroll, Thomas R.

1994-01-01

The major effort by HYD-6 members has been to develop a network of flight lines to provide the maximum amount of information on the temporal and spatial variation in soil moisture for the Boreal Ecosystem Atmosphere Study (BOREAS) study areas. Field visits to the southern study area (SSA) were conducted during May 1993 to obtain first hand information on the flight lines that had been previously selected for BOREAS snow studies. In September 1993 airborne gamma radiation surveys were conducted over the SSA, the northern study area (NSA), and for five flight lines along the transect between the two study areas. In situ measurements of soil moisture and water content of the moss/humus layer were obtained for calibration of selected gamma radiation flights lines in the SSA and for two of the transit lines. The flight lines for which soil moisture will be measured during the three IFC's during the summer of 1994 is a subset of the total flight lines that have been flown for the snow surveys. During the WFC in February 1994, airborne gamma radiation surveys were flown over all of the flight lines. Members of HYD-4 collected in-situ measurements (soil moisture, water content of the moss/humus layer, and water equivalent of the snow cover).

[Immobilization impact of different fixatives on heavy metals contaminated soil].

PubMed

Wu, Lie-shan; Zeng, Dong-mei; Mo, Xiao-rong; Lu, Hong-hong; Su, Cui-cui; Kong, De-chao

2015-01-01

Four kinds of amendments including humus, ammonium sulfate, lime, superphosphate and their complex combination were added to rapid immobilize the heavy metals in contaminated soils. The best material was chosen according to the heavy metals' immobilization efficiency and the Capacity Values of the fixative in stabilizing soil heavy metals. The redistributions of heavy metals were determined by the European Communities Bureau of Referent(BCR) fraction distribution experiment before and after treatment. The results were as follows: (1) In the single material treatment, lime worked best with the dosage of 2% compared to the control group. In the compound amendment treatments, 2% humus combined with 2% lime worked best, and the immobilization efficiency of Pb, Cu, Cd, Zn reached 98.49%, 99.40%, 95.86%, 99.21%, respectively. (2) The order of Capacity Values was lime > humus + lime > ammonium sulfate + lime > superphosphate > ammonium sulfate + superphosphate > humus + superphosphate > humus > superphosphate. (3) BCR sequential extraction procedure results indicated that 2% humus combined with 2% lime treatment were very effective in immobilizing heavy metals, better than 2% lime treatment alone. Besides, Cd was activated firstly by 2% humus treatment then it could be easily changed into the organic fraction and residual fraction after the subsequent addition of 2% lime.

[Effects of long-term localized fertilization on soil humus combining form in sheltered vegetable field].

PubMed

Zhang, Hongling; Liang, Chenghua; Du, Liyu; Chen, Xinzhi; Li, Jibai

2006-05-01

The study showed that on a sheltered vegetable field, a long-term application of organic plus chemical fertilizers induced a higher content of loosely combined soil humus than applying chemical fertilizers alone, while there was no significant difference in firmly combined humus content among different fertilization treatments. More tightly combined humus was observed in organic fertilizer treatments than in chemical fertilizer treatments, and the highest content (11.53 g x kg(-1)) was in the treatment of organic fertilizer plus chemical NPK. The ratio of loosely/tightly combined humus tended to decrease after a long-term application of organic fertilizer, being the lowest (1.10) in the treatment of organic fertilizer plus chemical NPK.

Postpyrogenic Polycyclic Soils in the Forests of Yakutia and Transbaikal region

NASA Astrophysics Data System (ADS)

Chevychelov, A. P.; Shakhmatova, E. Y.

2018-02-01

Periodical forest fires are typical natural events under the environmental and climatic conditions of central and southern Yakutia and Transbaikal region of Russia. Strong surface fires activate exogenous geomorphological processes. As a result, soils with polycyclic profiles are developed in the trans-accumulative landscape positions. These soils are specified by the presence of two-three buried humus horizons with abundant charcoal under the modern humus horizon. This indicates that these soils have been subjected to two-three cycles of zonal pedogenesis during their development. The buried pyrogenic humus horizons accumulate are enriched in humus; nitrogen; total and oxalate-extractable iron; exchangeable bases (Ca+2 and Mg+2); and the fractions of coarse silt, physical clay (<0.01 mm), and clay (<0.001 mm) particles in comparison with the neighboring mineral horizons of the soil profile. The humus of buried pyrogenic horizons is characterized by the increased content of humic acids, particularly, those bound with mobile sesquioxides (HA-1) and calcium (HA-2) and by certain changes in the type of humus.

Protection against atypical Aeromonas salmonicida infection in carp (Cyprinus carpio L.) by oral administration of humus extract.

PubMed

Kodama, Hiroshi; Denso; Nakagawa, Tsuyoshi

2007-04-01

Humic substances are formed during the decomposition of organic matter in humus, and are found in many natural environments in which organic materials and microorganisms have been present. In the present study, oral administration of humus extract to common carp (Cyprinus carpio L.) induced effective protection against experimental atypical Aeromonas salmonicida infection. Mortality of fish and development of skin lesions such as hemorrhages and ulcers were significantly suppressed in carp treated with 10%, 5% or 1% humus extract adsorbed on dry feeding pellets. The median surviving days was also greater in fish treated with 10% or 5% humus extract than in untreated fish. Atypical A. salmonicida was isolated from ulcerative lesions of part of dead fish, but Aeromonas hydrophila and Flavobacterium sp. were also isolated from these fish, verifying bacterial population changes during the progression of skin lesions. These results clearly show that treatment of fish with humus extract is effective in preventing A. salmonicida disease.

Transformation of humus substances in the long-drained surface-gleyed soddy-podzolic soils under conditions of pronounced microrelief and different agrogenic loads

NASA Astrophysics Data System (ADS)

Ovchinnikova, M. F.

2016-08-01

The transformation of humus substances resulting from artificial drainage of the surface-gleyed soddy-podzolic soils under conditions of pronounced microtopography and different agrogenic loads was studied. The studied soil characteristics included acid-base conditions, the content and group composition of humus, the ratios between the fractions of humus acids, and optical density of humic acids. The features attesting to humus degradation were found in the soils of microdepressions periodically subjected to excessive surface moistening, in the soils of different landforms upon the construction of drainage trenches, and in the plowed non-fertilized soils. The response of humus characteristics to the changes in the ecological situation in the period of active application of agrochemicals for reclamation of the agrotechnogenically disturbed soils was traced. It was shown that the long-term dynamics of the particular parameters of the biological productivity of the soil depend on the hydrological and agrogenic factors, as well as on the weather conditions.

Fate of chromium in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prokisch, J.; Gyori, Z.; Kovacs, B.

The chromium cycle in soil was studied with speciation of chromium. The aim was to look for the possibilities the mobilization of chromium(III) and to measure the rate of chromate reduction in nature and pot and field experiments in Hungarian soils. The authors developed a sensitive and simple method for chromium speciation with a microcolumn connected an inductively coupled plasma atomic emission spectrometer. Detection limits are convenient to measure chromium forms in a 0.01 M CaCl{sub 2} extract of a contaminated soil, but it is not enough to measure that of the uncontaminated soils. CR(VI) as chromate anion is notmore » adsorbed on pH dependent temporary charges of clays but in strongly acidic soil. Therefore CR(VI) can be leached out easily from the top layer of soil and can be transported into the ground water. Chromate ion can be reduced to CR(III) by organic matter of soil in acidic medium. CR(VI) is more stable at higher pH and lower humus content. Thus the reduction much quicker in the upper, weakly acidic top layer. CR(VI) oxidizes the organic matter of soil. The rate of this reaction depends on pH values, the humus content of the soil and temperature. CR(III) leaching in different uncontaminated soils was studied too. There are 3 pathways of mobilization of Cr(III). When pH decreases in soil the CR(III) becomes more soluble, similarly to the aluminium(III) ion. When the soil contains large quantity of water soluble organic ligands, Cr makes complexes with them and complexes formed can be leached out from the top layer. The third possibility is the oxidation of CR(III) to Cr(VI). It could happen on surface of manganese dioxide in the well-aired top layer.« less

7 CFR 319.40-6 - Universal importation options.

Code of Federal Regulations, 2014 CFR

2014-01-01

... treated with moisture reduction in accordance with part 305 of this chapter. (d) Wood mulch, humus, compost, and litter. Wood mulch, humus, compost, and litter may be imported if accompanied by an importer document stating that the wood mulch, humus, compost, or litter was fumigated in accordance with part 305...

7 CFR 319.40-6 - Universal importation options.

Code of Federal Regulations, 2012 CFR

2012-01-01

... treated with moisture reduction in accordance with part 305 of this chapter. (d) Wood mulch, humus, compost, and litter. Wood mulch, humus, compost, and litter may be imported if accompanied by an importer document stating that the wood mulch, humus, compost, or litter was fumigated in accordance with part 305...

7 CFR 319.40-6 - Universal importation options.

Code of Federal Regulations, 2013 CFR

2013-01-01

... treated with moisture reduction in accordance with part 305 of this chapter. (d) Wood mulch, humus, compost, and litter. Wood mulch, humus, compost, and litter may be imported if accompanied by an importer document stating that the wood mulch, humus, compost, or litter was fumigated in accordance with part 305...

Evaluation of mercury contamination using plant leaves and humus as indicators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamura, R.; Fukuzaki, N.; Hirano, Y.

Plant leaves and humus were collected from three areas with and without mercury emission sources. Mercury in these samples were determined by cold flameless atomic absorption spectrometry. A part of mercury emitted from the source into the atmosphere is absorbed by plant leaves, and move to humus through fallen leaves. Consequently, plant leaves are able to be used as an indicator for the evaluation of mercury in air at present. Humus is useful for the evaluation of mercury contamination through the air from the past to present.

Effect of species composition on carbon and nitrogen stocks in forest floor and mineral soil in Norway spruce and European beech mixed forests

NASA Astrophysics Data System (ADS)

Andivia, Enrique; Rolo, Víctor; Jonard, Mathieu; Formánek, Pavel; Ponette, Quentin

2015-04-01

Management of existing forests has been identified as the main strategy to enhance carbon sequestration and to mitigate the impact of climate change on forest ecosystems. In this direction, the conversion of Norway spruce monospecific stands into mixed stands by intermingling individuals of European beech is an ongoing trend in adaptive forest management strategies, especially in Central Europe. However, studies assessing the effect of changes in tree species composition on soil organic carbon (SOC) and nitrogen stocks are still scarce and there is a lack of scientific evidence supporting tree species selection as a feasible management option to mitigate the effects of predicted future climatic scenarios. We compared C and N stocks in the forest floor (litter and humus) and the top 10 cm of mineral soil in two monospecific stands of Norway spruce and European beech and in a mixed stand of both species. The effect of tree species composition on the C and N stocks and its spatial distribution was evaluated based on litterfall, root production, elevation and canopy opening, and by using a combination of modelling and geostatistical techniques. C stock was highest in the Norway spruce and the mixed stands, while N stock was highest in the mixed stand and lowest under European beech, with intermediate values in the Norway spruce stand. Each forest type showed differences in forest floor properties, suggesting that species composition is an important factor governing forest floor characteristics, including C and N stocks. The distribution of C and N stocks between forest soil layers was different for each forest type. C and N stocks were highest in the hummus layer under Norway spruce, whereas both stocks were lowest in the European beech stand. On the other hand, the mixed stand showed the highest C and N accumulation in the uppermost mineral soil layer, while the monospecific stands showed similar values. Litterfall was the main contribution to C and N stocks of the humus layer in monospecific stands. Forest floor stocks were also influenced by microelevation and canopy opening in the European beech stand and by microelevation in the Norway spruce stand. Root turnover and Norway spruce litterfall proportion directly increased C stocks in the mineral soil of the mixed stand. Additionally, N stock in the forest floor of the mixed stand was positively correlated with the Norway spruce litterfall proportion. Spatial analyses further confirmed that species composition was the main source of spatial variability of SOC stock in mixed stands. These results suggest that the admixture of individuals of European beech and Norway spruce may lead to a translocation of SOC from the forest floor to the better protected mineral soil layer, which might be beneficial for long term SOC sequestration.

Earthworm impacts on organo-mineral interactions and soil carbon inventories in Fennoscandian boreal and sub-arctic landscapes

NASA Astrophysics Data System (ADS)

Wackett, Adrian; Yoo, Kyungsoo; Cameron, Erin; Klaminder, Jonatan

2017-04-01

Boreal and sub-arctic environments sustain some of the most pristine and fragile ecosystems in the world and house a disproportionate amount of the global soil carbon pool. Although the historical view of soil carbon turnover has focused on the intrinsic molecular structure of organic matter, recent work has highlighted the importance of stabilizing soil carbon on reactive mineral surfaces. However, the rates and mechanisms controlling these processes at high latitudes are poorly understood. Here we explored the biogeochemical impacts of deep-burrowing earthworm species on a range of Fennoscandian forest soils to investigate how earthworms impact soil carbon inventories and organo-mineral associations across boreal and sub-arctic landscapes. We sampled soils and earthworms at six sites spanning almost ten degrees latitude and encompassing a wide range of soil types and textures, permitting simultaneous consideration of how climate and mineralogy affect earthworm-mediated shifts in soil carbon dynamics. Across all sites, earthworms significantly decreased the carbon and nitrogen contents of the upper 10 cm, presumably through consumption of the humus layer and subsequent incorporation of the underlying mineral soil into upper organic horizons. Their mixing of humus and underlying soil also generally increased the proportion of mineral surface area occluded by organic matter, although the extent to which earthworms facilitate such organo-mineral interactions appears to be controlled by soil texture and mineralogy. This work indicates that quantitative measurements of mineral surface area and its extent of coverage by soil organic matter facilitate scaling up of molecular interactions between organic matter and minerals to the level of soil profiles and landscapes. Our preliminary data also strongly suggests that earthworms have profound effects on the fate of soil carbon and nitrogen in boreal and sub-arctic environments, highlighting the need for a better understanding of the joint ecological impacts of warming and indirect disturbances like earthworm introduction by humans to make sound predictions of future ecosystem change and carbon-climate feedbacks.

[Allelopathic effects of the humus soils from Betula platyphylla and Quercus liaotungensis pure plantations on 9 kinds of common shrubs and herbs].

PubMed

Huang, Liang-Jia; Liu, Zeng-wen; Zhu, Bo-Chao; Bing, Yuan-Hao; Zhang, Xiao-Xi; Lü, Chen

2014-06-01

The humus soils were collected from Betula platyphylla and Quercus liaotungensis pure plantations and woodless land separately where the site conditions were basically the same, and taken as medium for potting culture test of 9 kinds of shrubs or herbs in plastic greenhouse to assess the allelopathic effects of humus soils of pure plantations on shrubs or herbs. Humus soils from B. platyphylla plantation significantly inhibited the seed germinations of Medicago sativa and Melilotus officinalis, decreased the catalase (CAT) activity of M. officinalis, Coronilla varia, M. sativa and Lespedeza davurica, and improved malondialdehyde (MDA) contents in seedlings of Caragana kor-shinskii, C. varia and Astragalus adsurgens. The biomass growths of C. varia, Amorpha fruticosa, M. sativa, M. officinalis and A. adsurgens in humus soils from B. platyphylla plantation were significantly decreased by 48.2%, 45.1%, 44.3%, 37.3% and 36.0%, respectively. In addition, humus soil of Q. liaotungensis plantation significantly decreased the germination rates of M. sativa and A. adsurgens, the chlorophyll contents of Vicia villosa, A. fruticosa and M. sativa, and improved malondialdehyde (MDA) contents in seedlings of Lespedeza davurica, Caragana korshinskii, M. officinalis and A. adsurgens. The biomass growths of A. adsurgens, M. sativa, M. officinalis and A. fruticosa were significantly decreased by 52.6% , 43.8%, 35.5% and 34.6%, respective- ly. B. platyphylla plantation humus soil had obvious inhibition effects on M. sativa, M. officinalis and A. fruticosa, while Q. liaotungensis plantation humus soil had obvious inhibition effects on M. sativa, A. adsurgens and A. fruticosa.

Assessing the humus status and CO2 production in soils of anthropogenic and agrogenic landscapes in southern regions of the Russian Far East

NASA Astrophysics Data System (ADS)

Purtova, L. N.; Kostenkov, N. M.; Shchapova, L. N.

2017-01-01

The humus status and CO2 production have been assessed in soils of natural and anthropogenic landscapes in southern regions of the Far East with different types of redox conditions. A higher production of CO2 is typical of burozems and soddy-eluvial-metamorphic soils with oxidative and contrast redox conditions. These are soils with medium or high humus content, high potential humification capacity, and medium enrichment with catalase. A decrease in the content of humus in the plow horizons of soils in agrogenic landscapes is revealed compared to their natural analogues. The studied soils mainly have humus of the fulvate-humate type. The fractions strongly bound to the mineral soil component prevail in humic acids. In waterlogged mucky-humus gley soils, the anaerobic conditions hamper the biological activity and transformation of organic matter, which favors its accumulation. A low production of CO2 is observed in soils with reducing conditions. To determine the differences between the CO2 emission parameters in soils of agrogenic and natural landscapes, monitoring studies should be extended.

[Effect of sand-stabilization engineering on soil humus and components by analysis by several spectroscopy methods].

PubMed

Zhang, Yu-lan; Sun, Cai-xia; Duan, Zheng-hu; Chen, Li-jun; Wu, Zhi-jie; Chen, Xiao-hong; Zhang, Ai-ming; Liu, Xing-bin; Wang, Jun-yu

2010-01-01

After the potassium bichromate-strong sulfuric acid hot process, the ultraviolet spectrophotometer was used on the contrast with the traditional titrimetric method to analyze soil (51 years, 43 year, 32 year, 20 year vegetations restores in the Tenggeli sand) humus and the humus components content. At the same time, the infrared spectrum was used to discuss their structure change during restoring process. The result indicated that using the visible spectroscopy method for the determination of the humus and the humus component is feasible. The spectroscopy method determination of organic matter is better (coefficient of variation at most is 7.26%) than the traditional titrimetric method, as it is accurate, fast and simple, and favors large quantities. The result indicated that humus content presents increasing tendency along with restoring ages. Change is big in early restore time, and tends to be stable in the later period. Infrared spectrum shape is similar, but the characteristic peak intensity has obvious difference. Compared with the wind-drift sand, little molecule saccharides decrease and aryl-groups increase.

Promotion by humus-reducing bacteria for the degradation of UV254 absorbance in reverse-osmosis concentrates pretreated with O3-assisted UV-Fenton method.

PubMed

Xia, Jiaohui; Zhang, Hui; Ding, Shaoxuan; Li, Changyu; Ding, Jincheng; Lu, Jie

2017-07-12

The primary pollutants in reverse-osmosis concentrates (ROC) are the substances with the UV absorbance at 254 nm (UV 254 ), which is closely related to humic substances that can be degraded by humus-reducing bacteria. This work studied the degradation characteristics of humus-reducing bacteria in ROC treatment. The physiological and biochemical characteristics of humus-reducing bacteria were investigated, and the effects of pH values and electron donors on the reduction of humic analog, antraquinone-2, 6-disulfonate were explored to optimize the degradation. Furthermore, the O 3 -assisted UV-Fenton method was applied for the pretreatment of ROC, and the degradation of UV 254 absorbance was apparently promoted with their removal rate, reaching 84.2% after 10 days of degradation by humus-reducing bacteria.

[Humus composition of petroleum hydrocarbon-contaminated soil].

PubMed

Feng, Jun; Tang, Li-Na; Zhang, Jin-Jing; Dou, Sen

2008-05-01

An abandoned petroleum well which had been exploited for about twenty years in Songyuan city of Jilin Province, China, was selected to study the compositions and characteristics of soil humus using revised humus composition method and Simon-Kumada method. Soil samples were collected at 0.5, 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, 7.5 and 10.5 m apart from the well head. Results show that the petroleum contents increase from 0.08 g/kg (10.5 m to the well head) to 153.3 g/kg (0.5 m to the well head). With the increase in petroleum content, the contents of soil organic carbon and water soluble organic carbon increase; for total soil humus, the contents of extractable humus (HE) and humic acid (HA) decrease whereas that of humin (HM) increase; the percentage of HA/HE (PQ 72.0%-8.05%) decrease and HM/HE ratio (31.4-76.7) increase; for different combined humus, the contents of loosely combined humus (HI) and stably combined humus (HII) have a decrease tendency while that of tightly combined humus (HIII) increase; the HI/HII ratio (0.19-0.39) shows an increase tendency, whereas HI/HIII ratio (0.032-0.003) and HII/HIII ratio (0.096-0.009) decrease; the PQs of HI (3.21%-1.42%) and HIII (58.1%-35.5%) also decrease, and the range of PQ change is less in HI than in HII; the color coefficient (deltalogk) of water soluble organic matter (WSOM) decreases, whereas no obvious change for HA. The above results indicate that petroleum hydrocarbon promotes the formation of HM but not HA. The decrease in HA is mainly due to the restraining effect of petroleum hydrocarbon on the formation of stably combined HA. Petroleum hydrocarbon leads molecular structure of WSOM more complex but no effect on molecular structure of HA.

RADIOCARBON DATING: A CASE AGAINST THE PROPOSED LINK BETWEEN RIVER MOLLUSKS AND SOIL HUMUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broecker, W.

The C/sup 14/ link between river mollusks and soil humus is discussed. It is stated that the explanation that the C/sup 13/ deficiency should be attributed to the uptake of soil CO/sub 2/ by ground water (oxidation of humus in the soil, rather than after it has been transported into streams) and the C/sup 14/ deficiency to the solution of limestone is far more plausible. It was concluded that any relation between the radiocarbon concentrations in soil humus and fresh water mollusks is almost certainly coincidental. (P.C.H.)

Persistence of 137Cs in the litter layers of forest soil horizons of Mount IDA/Kazdagi, Turkey.

PubMed

Karadeniz, Özlem; Karakurt, Hidayet; Çakır, Rukiye; Çoban, Fatih; Büyükok, Emir; Akal, Cüneyt

2015-01-01

In 2010-2012, an extensive study was performed in forest sites of Mount IDA (Kazdagi)/Edremit 26 years after the Chernobyl accident. The (137)Cs activity concentrations were determined by gamma-ray spectrometry in the forest soil layers (OL, OF + OH and A horizons) separately. Based on 341 surface soil samples and 118 soil profiles, activity concentrations of (137)Cs in OL horizons varied between 0.25 ± 0.14 and 70 ± 1 Bq kg(-1), while the ranges of (137)Cs activity concentrations in OF + OH and A horizons were 13 ± 1-555 ± 3 Bq kg(-1) and 2 ± 1-253 ± 2 Bq kg(-1), respectively. Cesium-137 deposition in the study area was estimated to be in the range of 1-39 kBq m(-2) and a linear relationship between the deposition of (137)Cs and the altitude was observed. The distributions of (137)Cs activities in OL, OF + OH and A horizons throughout the region were mapped in detail. The highest (137)Cs activities were found in OF + OH horizons, with markedly lower (137)Cs activity in mineral horizons of soil profiles. It is observed that (137)Cs content of humus layer increases with the thickness of the humus layer for coniferous forest sites. The (137)Cs activity concentrations were higher than the recommended screening limits (150 Bq kg(-1)) at some of the investigated areas. The current activity concentration of top soil layers indicates that over many years since the initial deposition, (137)Cs activity is keeping still high in the organic horizons. Copyright © 2014 Elsevier Ltd. All rights reserved.

Attraction to Carbon Dioxide from Feeding Resources and Conspecific Neighbours in Larvae of the Rhinoceros Beetle Trypoxylus dichotomus

PubMed Central

Kojima, Wataru

2015-01-01

Saprophagous (feeding on decaying matter) insects often use carbon dioxide (CO2) as a cue for finding food. Humus-feeding larvae of the giant rhinoceros beetle Trypoxylus dichotomus exhibit a clumped distribution in natural microhabitats, but the mechanisms driving the distribution were unknown. Herein, I examined whether larvae use CO2 as a cue for fermented humus and aggregate in the vicinity of the food. I found that (i) larvae of T. dichotomus are strongly attracted to CO2, (ii) larvae orient toward highly fermented humus when given a choice between highly and poorly fermented humus, (iii) the highly fermented humus emits more CO2 than the poorly fermented humus, and (iv) larvae grow larger when fed highly fermented humus rather than poorly fermented humus. The clumped distribution of larvae is probably formed along the concentration gradient of CO2 induced by heterogeneity of fermented organic materials in soil. My laboratory experiments also revealed that larvae are chemically attracted to each other. Moreover, CO2 concentrations in soil were increased by the larval respiration, and small amounts of CO2 (much less than emitted during respiration by a single larva) were sufficient for larval attraction. These results suggest that not only response to fermented food resources, but also respiratory CO2 from conspecifics may lead to aggregation. Enhanced densities resulted in reduced weight gain under experimental conditions. However, exploiting a high-value resource at enhanced densities still led to greater body weight compared to individually exploiting a low-value resource. This demonstrates the adaptive value of the response to CO2 sources in this species. PMID:26536591

Pyrene degradation in forest humus microcosms with or without pine and its mycorrhizal fungus.

PubMed

Koivula, Teija T; Salkinoja-Salonen, Mirja; Peltola, Rainer; Romantschuk, Martin

2004-01-01

The mineralization potential of forest humus and the self-cleaning potential of a boreal coniferous forest environment for polycyclic aromatic hydrocarbon (PAH) compounds was studied using a model ecosystem of acid forest humus (pH = 3.6) and pyrene as the model compound. The matrix was natural humus or humus mixed with oil-polluted soil in the presence and absence of Scots pine (Pinus sylvestris L.) and its mycorrhizal fungus (Paxillus involutus). The rates of pyrene mineralization in the microcosms with humus implants (without pine) were initially insignificant but increased from Day 64 onward to 47 microg kg(-1) d(-1) and further to 144 microg kg(-1) d(-1) after Day 105. In the pine-planted humus microcosms the rate of mineralization also increased, reaching 28 microg kg(-1) d(-1) after Day 105. The 14CO2 emission was already considerable in nonplanted microcosms containing oily soil at Day 21 and the pyrene mineralization continued throughout the study. The pyrene was converted to CO2 at rates of 0.07 and 0.6 microg kg(-1) d(-1) in the oily-soil implanted microcosms with and without pine, respectively. When the probable assimilation of 14CO2 by the pine and ground vegetation was taken into account the most efficient microcosm mineralized 20% of the 91.2 mg kg(-1) pyrene in 180 d. The presence of pine and its mycorrhizal fungus had no statistically significant effect on mineralization yields. The rates of pyrene mineralization observed in this study for forest humus exceeded the total annual deposition rate of PAHs in southern Finland. This indicates that accumulation in forest soil is not to be expected.

Attraction to Carbon Dioxide from Feeding Resources and Conspecific Neighbours in Larvae of the Rhinoceros Beetle Trypoxylus dichotomus.

PubMed

Kojima, Wataru

2015-01-01

Saprophagous (feeding on decaying matter) insects often use carbon dioxide (CO2) as a cue for finding food. Humus-feeding larvae of the giant rhinoceros beetle Trypoxylus dichotomus exhibit a clumped distribution in natural microhabitats, but the mechanisms driving the distribution were unknown. Herein, I examined whether larvae use CO2 as a cue for fermented humus and aggregate in the vicinity of the food. I found that (i) larvae of T. dichotomus are strongly attracted to CO2, (ii) larvae orient toward highly fermented humus when given a choice between highly and poorly fermented humus, (iii) the highly fermented humus emits more CO2 than the poorly fermented humus, and (iv) larvae grow larger when fed highly fermented humus rather than poorly fermented humus. The clumped distribution of larvae is probably formed along the concentration gradient of CO2 induced by heterogeneity of fermented organic materials in soil. My laboratory experiments also revealed that larvae are chemically attracted to each other. Moreover, CO2 concentrations in soil were increased by the larval respiration, and small amounts of CO2 (much less than emitted during respiration by a single larva) were sufficient for larval attraction. These results suggest that not only response to fermented food resources, but also respiratory CO2 from conspecifics may lead to aggregation. Enhanced densities resulted in reduced weight gain under experimental conditions. However, exploiting a high-value resource at enhanced densities still led to greater body weight compared to individually exploiting a low-value resource. This demonstrates the adaptive value of the response to CO2 sources in this species.

[Humus composition of black soil and its organo-mineral complexes under different fertility level].

PubMed

Zhao, Lanpo; Wang, Jie; Liu, Jingshuan; Liu, Shuxia; Wang, Yanling; Wang, Hongbin; Zhang, Zhidan

2005-01-01

Determinations by Kumada method showed that with the improvement of black soil fertility, the free and combined humus contents in soil and its different size organo-mineral complexes increased, but the humification degree of free humus decreased, which was more obvious in silt and fine sand size complexes. The organic carbon content in complexes, humus extraction rate, free humus content, and humification degree of free humic acid decreased with the increasing particle size of complexes. All free humic acids in fertile soil were Rp type, while in unfertile soil, they were Rp and B type. With the increasing particle size of complexes, the type of free humic acids changed in the sequence A type (clay)-->B type (silt)-->Rp type (fine sand). Combined form humic acid mainly belonged to A type, no matter what particle size the complex was. The improvement of soil fertility could make the humification degree of free humus in soil and its complexes decrease, and furthermore, result in type change. In black soil, the type change of free humic acid mainly occurred in silt size complex, and that of combined form humic acid mainly occurred in fine sand size complex.

Sorption of VX to Clay Minerals and Soils: Thermodynamic and Kinetic Studies

DTIC Science & Technology

2012-12-01

Suspengel 200, humus , and soil substrates for use in this study. In addition, the authors gratefully acknowledge the support of the ECBC Technical...sorption profiles for VX with clay substrates ..................................55 30. Initial kinetic sorption profiles for VX with humus ...naturally derived garden soil amendment, identified as humus , was purchased from Frey Brothers (Quarryville, PA). Two natural soils, identified as MCL lot

Missouri River, Gavins Point Dam - Lewis and Clark Lake, Nebraska and South Dakota, Embankment Criteria and Performance Report.

DTIC Science & Technology

1982-05-01

FOUNDATION PREPARATION. All areas upon which embankment material were placed, plus at least a 10-foot contiguous strip, were cleared of all brush, trees ...feet below the ground surface. Thin surface layers containing sod, humus , and other undesirable material were stripped and wasted. Depressions were...section consisting of the thick IV on 15R berm section and the thinner IV on 411 upper main embankment section. The speci - fications allowed the material

Linking chemical elements in forest floor humus (Oh-horizon) in the Czech Republic to contamination sources.

PubMed

Sucharova, Julie; Suchara, Ivan; Hola, Marie; Reimann, Clemens; Boyd, Rognvald; Filzmoser, Peter; Englmaier, Peter

2011-05-01

While terrestrial moss and other plants are frequently used for environmental mapping and monitoring projects, data on the regional geochemistry of humus are scarce. Humus, however, has a much larger life span than any plant material. It can be seen as the "environmental memory" of an area for at least the last 60-100 years. Here concentrations of 39 elements determined by ICP-MS and ICP AES, pH and ash content are presented for 259 samples of forest floor humus collected at an average sample density of 1 site/300 km2 in the Czech Republic. The scale of anomalies linked to known contamination sources (e.g., lignite mining and burning, metallurgical industry, coal fired power plants, metal smelters) is documented and discussed versus natural processes influencing humus quality. Most maps indicate a local impact from individual contamination sources: often more detailed sampling than used here would be needed to differentiate between likely sources. Copyright © 2011 Elsevier Ltd. All rights reserved.

Protection against Flavobacterium psychrophilum infection (cold water disease) in Ayu fish (Plecoglossus altivelis) by oral administration of humus extract.

PubMed

NAKAGAWA, Jun; IWASAKI, Tadashi; KODAMA, Hiroshi

2009-11-01

Humic substances are formed during the decomposition of organic matter in humus, and are found in many natural environments in which organic materials and microorganisms have been present. In the present study, oral administration of humus extract to ayu fish (Plecoglossus altivelis) induced effective protection against experimental Flavobacterium psychrophilum infection (cold water disease). Mortality of fish and development of skin lesions, such as erosion and hemorrhages on the skin, gill cover or mouth, were significantly suppressed in fish treated with 10%, 5% or 1% humus extract adsorbed on dry pellets. Although F. psychrophilum was not re-isolated from gills and erosion lesions of the skin of dead fish, bacterial gyrB DNA could be amplified in these specimens from dead fish and surviving control fish using the polymerase chain reaction. The protective effect of the extract was not the results of direct killing of bacteria or antibiotic activity of the extract since no obvious reduction in the bacterial number was observed at 5 times to 5,000 times dilution of the humus extract having pH 5.45 to 7.40. These results clearly show that treating fish with humus extract is effective in preventing cold water disease.

Seasonal changes in soil acidity and related properties in ginseng artificial bed soils under a plastic shade

PubMed Central

You, Jiangfeng; Liu, Xing; Zhang, Bo; Xie, Zhongkai; Hou, Zhiguang; Yang, Zhenming

2014-01-01

Background In Changbai Mountains, Panax ginseng (ginseng) was cultivated in a mixture of the humus and albic horizons of albic luvisol in a raised garden with plastic shade. This study aimed to evaluate the impact of ginseng planting on soil characteristics. Methods The mixed-bed soils were seasonally collected at intervals of 0–5 cm, 5–10 cm, and 10–15 cm for different-aged ginsengs. Soil physico-chemical characteristics were studied using general methods. Aluminum was extracted from the soil solids with NH4Cl (exchangeable Al) and Na-pyrophosphate (organic Al) and was measured with an atomic absorption spectrophotometer. Results A remarkable decrease in the pH, concentrations of exchangeable calcium, NH4+, total organic carbon (TOC), and organic Al, as well as a pronounced increase in the bulk density were observed in the different-aged ginseng soils from one spring to the next. The decrease in pH in the ginseng soils was positively correlated with the NH4+ (r = 0.463, p < 0.01), exchangeable calcium (r = 0.325, p < 0.01) and TOC (r = 0.292, p < 0.05) concentrations. The NO3− showed remarkable surface accumulation (0–5 cm) in the summer and even more in the autumn but declined considerably the next spring. The exchangeable Al fluctuated from 0.10 mg g−1 to 0.50 mg g−1 for dry soils, which was positively correlated with the NO3− (r = 0.401, p < 0.01) and negatively correlated with the TOC (r = −0.329, p < 0.05). The Al saturation varied from 10% to 41% and was higher in the summer and autumn, especially in the 0–5 cm and 5–10 cm layers. Conclusion Taken together, our study revealed a seasonal shift in soil characteristics in ginseng beds with plastic shade. PMID:25535481

Signatures of chlorinated dioxins and furans along the exposure path - The relation between vegetation and soil.

PubMed

Hangen, Edzard; Gonser, Stefan; Köhler, Jutta

2018-08-01

Polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) belong to the most toxic persistent organic environmental pollutants. Therefore, knowledge about their fate along the exposure path is of special concern. In order to comprehend the transfer of PCDD/Fs across different environmental compartments, PCDD/F concentrations in plants and in soil were evaluated. Pairs of soil and plant samples were selected according to the shortest distance between sampling points. At 15 sites PCDD/F concentrations in spruce needles and in forest humus layers where compared. Summer conditions were evaluated on the basis of 8 sites with ryegrass- and grassland topsoil samples. Autumn conditions were addressed using 7 sites with curly kale and topsoil samples under grassland. Correlation analyses of the PCDD/F congener profiles for plant- and soil samples were conducted. The correlations were compared to influencing site (e.g. local temperature) and spatial as well as temporal offset parameters. No governing parameter that decisively influenced the similarity between plant and soil signature became evident. By means of the toxicity factors of TEQ-WHO, tetra- and penta-PCDD/F homologues were assigned to the group of low-chlorinated homologues (lcH), and hexa-, hepta- and octa-PCDD/F homologues to the high-chlorinated homologues (hcH). lcH and hcH are presumed to differ in solubility, volatility and rate of degradation. The ratio of lcH/hcH revealed characteristic fingerprints that enabled the differentiation of the individual PCDD/F-plant and -soil pairs. Spruce-humus pairs showed a close relation during winter exposure times, while the lower summer concentrations were not reflected in the humus layer. Kale was exposed at the beginning of the season with elevated PCDD/F immissions, and showed a closer relation to grassland topsoil than did ryegrass. lcH/hcH proved as a simple criterion that can reveal related PCDD/F fingerprints of different environmental compartments despite signal attenuation due to decomposition, volatilization and particulate transport. Copyright © 2018 Elsevier B.V. All rights reserved.

7 CFR 319.40-1 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... with the requirements specified by the general permit, without being issued a specific permit. Humus... wood packing materials; humus; compost; litter; and wooden handicrafts. Regulated wood packaging...

Continuous soil carbon storage of old permanent pastures in Amazonia.

PubMed

Stahl, Clément; Fontaine, Sébastien; Klumpp, Katja; Picon-Cochard, Catherine; Grise, Marcia Mascarenhas; Dezécache, Camille; Ponchant, Lise; Freycon, Vincent; Blanc, Lilian; Bonal, Damien; Burban, Benoit; Soussana, Jean-François; Blanfort, Vincent

2017-08-01

Amazonian forests continuously accumulate carbon (C) in biomass and in soil, representing a carbon sink of 0.42-0.65 GtC yr -1 . In recent decades, more than 15% of Amazonian forests have been converted into pastures, resulting in net C emissions (~200 tC ha -1 ) due to biomass burning and litter mineralization in the first years after deforestation. However, little is known about the capacity of tropical pastures to restore a C sink. Our study shows in French Amazonia that the C storage observed in native forest can be partly restored in old (≥24 year) tropical pastures managed with a low stocking rate (±1 LSU ha -1 ) and without the use of fire since their establishment. A unique combination of a large chronosequence study and eddy covariance measurements showed that pastures stored between -1.27 ± 0.37 and -5.31 ± 2.08 tC ha -1  yr -1 while the nearby native forest stored -3.31 ± 0.44 tC ha -1  yr -1 . This carbon is mainly sequestered in the humus of deep soil layers (20-100 cm), whereas no C storage was observed in the 0- to 20-cm layer. C storage in C4 tropical pasture is associated with the installation and development of C3 species, which increase either the input of N to the ecosystem or the C:N ratio of soil organic matter. Efforts to curb deforestation remain an obvious priority to preserve forest C stocks and biodiversity. However, our results show that if sustainable management is applied in tropical pastures coming from deforestation (avoiding fires and overgrazing, using a grazing rotation plan and a mixture of C3 and C4 species), they can ensure a continuous C storage, thereby adding to the current C sink of Amazonian forests. © 2016 John Wiley & Sons Ltd.

7 CFR 319.40-1 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... permit, without being issued a specific permit. Humus, compost, and litter. Partially or wholly decayed... shavings; pickets; stakes; shingles; solid wood packing materials; humus; compost; litter; and wooden...

Impact of vent pipe diameter on characteristics of waste degradation in semi-aerobic bioreactor landfill.

PubMed

Jiang, Guobin; Liu, Dan; Chen, Weiming; Ye, Zhicheng; Liu, Hong; Li, Qibin

2017-10-01

The evolution mechanism of a vent pipe diameter on a waste-stabilization process in semi-aerobic bioreactor landfills was analyzed from the organic-matter concentration, biodegradability, spectral characteristics of dissolved organic matter, correlations and principal-component analysis. Waste samples were collected at different distances from the vent pipe and from different landfill layers in semi-aerobic bioreactor landfills with different vent pipe diameters. An increase in vent pipe diameter favored waste degradation. Waste degradation in landfills can be promoted slightly when the vent pipe diameter increases from 25 to 50 mm. It could be promoted significantly when the vent pipe diameter was increased to 75 mm. The vent pipe diameter is important in waste degradation in the middle layer of landfills. The dissolved organic matter in the waste is composed mainly of long-wave humus (humin), short-wave humus (fulvic acid) and tryptophan. The humification levels of the waste that was located at the center of vent pipes with 25-, 50- and 75-mm diameters were 2.2682, 4.0520 and 7.6419 Raman units, respectively. The appropriate vent pipe diameter for semi-aerobic bioreactor landfills with an 800-mm diameter was 75 mm. The effect of different vent pipe diameters on the degree of waste stabilization is reflected by two main components. Component 1 is related mainly to the content of fulvic acid, biologically degradable material and organic matter. Component 2 is related mainly to the content of tryptophan and humin from the higher vascular plants.

Anaerobic humus and Fe(III) reduction and electron transport pathway by a novel humus-reducing bacterium, Thauera humireducens SgZ-1.

PubMed

Ma, Chen; Yu, Zhen; Lu, Qin; Zhuang, Li; Zhou, Shun-Gui

2015-04-01

In this study, an anaerobic batch experiment was conducted to investigate the humus- and Fe(III)-reducing ability of a novel humus-reducing bacterium, Thauera humireducens SgZ-1. Inhibition tests were also performed to explore the electron transport pathways with various electron acceptors. The results indicate that in anaerobic conditions, strain SgZ-1 possesses the ability to reduce a humus analog, humic acids, soluble Fe(III), and Fe(III) oxides. Acetate, propionate, lactate, and pyruvate were suitable electron donors for humus and Fe(III) reduction by strain SgZ-1, while fermentable sugars (glucose and sucrose) were not. UV-visible spectra obtained from intact cells of strain SgZ-1 showed absorption peaks at 420, 522, and 553 nm, characteristic of c-type cytochromes (cyt c). Dithionite-reduced cyt c was reoxidized by Fe-EDTA and HFO (hydrous ferric oxide), which suggests that cyt c within intact cells of strain SgZ-1 has the ability to donate electrons to extracellular Fe(III) species. Inhibition tests revealed that dehydrogenases, quinones, and cytochromes b/c (cyt b/c) were involved in reduction of AQS (9, 10-anthraquinone-2-sulfonic acid, humus analog) and oxygen. In contrast, only NADH dehydrogenase was linked to electron transport to HFO, while dehydrogenases and cyt b/c were found to participate in the reduction of Fe-EDTA. Thus, various different electron transport pathways are employed by strain SgZ-1 for different electron acceptors. The results from this study help in understanding the electron transport processes and environmental responses of the genus Thauera.

The influece of forest gaps on some properties of humus in a managed beech forest, northern Iran

NASA Astrophysics Data System (ADS)

Vajari, K. A.

2015-10-01

The present research focuses on the effect of eight-year-old artificially created gaps on some properties of humus in managed beech-dominated stand in Hyrcanian forest of northern Iran. In this study, six-teen gaps were sampled in site and were classified into four classes (small, medium, large, and very large) with four replications for each. Humus sampling was carried out at the centre and at the cardinal points within each gap as well as in the adjacent closed stand, separately, as composite samples. The variables of organic carbon, P, K, pH, and total N were measured for each sample. It was found that the gap size had significant effect only on total N (%) and organic carbon (%) in beech stand. The amount of potassium clearly differed among three positions in beech forest. The adjacent stand had higher significantly potassium than center and edge of gaps. Different amount of potassium was detected in gap center and gap edge. Comparison of humus properties between gaps and its adjacent stand pointed to the higher amount of potassium in adjacent stand than that in gaps but there was no difference between them regarding other humus properties. According to the results, it can be concluded that there is relatively similar condition among gaps and closed adjacent stands in terms of humus properties eight years after logging in the beech stand.

7 CFR 319.40-1 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... issued a specific permit. Humus, compost, and litter. Partially or wholly decayed plant matter. Import... materials; humus; compost; and litter. Regulated wood packaging material. Wood packaging material other than...

7 CFR 319.40-1 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... issued a specific permit. Humus, compost, and litter. Partially or wholly decayed plant matter. Import... materials; humus; compost; and litter. Regulated wood packaging material. Wood packaging material other than...

7 CFR 319.40-1 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... issued a specific permit. Humus, compost, and litter. Partially or wholly decayed plant matter. Import... materials; humus; compost; and litter. Regulated wood packaging material. Wood packaging material other than...

Uptake of cations under two different water regimes in a boreal scots pine forest.

PubMed

Plamboeck, A H; Nylén, T; Grip, H

2000-07-10

There is still much to find out about how trees react to changing nutrient conditions. In this cation uptake study, 134Cs and 22Na were injected between the humus and the mineral soil, and into a 20-cm depth in the mineral soil, respectively. Half of the experimental site was subjected to desiccation in 1995 and 1996, while the other half was subjected to irrigation in 1995, and desiccation in 1996. One month after the injections, the concentration of 134Cs in the xylem sap was higher in the irrigated plots (ID) than in the desiccated plots (DD). In August 1995, the difference in the 134Cs concentration in the xylem sap was even higher between the treatments. In 1995, 22Na was also higher in the xylem sap on the ID plots than on the DD plots, but not significantly. Exponential relationships were found between the amount of 134Cs and 22Na in the xylem sap; the relative water uptake from humus and 0-10-cm mineral soil (134Cs); and 10-25-cm mineral soil (22Na) in July 1995, when the tracers had not yet reached the top of the boles. The relative uptake of injected 22Na was larger than that of injected 134Cs, probably due to low exchangeability of Cs in the soil. One year after the injection (1996), more 134Cs was found in the wood, bark, needles and cones on the plots irrigated in 1995 than on the desiccated plots. The content of 134Cs in the stem wood and stump amounted to nearly 80% of the total uptake in the trees. The Cs distribution 1 year after the Chernobyl accident was dominated by Cs on/in needles and bark. After 10 years of redistribution, the Chernobyl Cs content of the different parts of the trees approached that of K.

Influence of crop rotation, intermediate crops, and organic fertilizers on the soil enzymatic activity and humus content in organic farming systems

NASA Astrophysics Data System (ADS)

Marcinkeviciene, A.; Boguzas, V.; Balnyte, S.; Pupaliene, R.; Velicka, R.

2013-02-01

The influence of crop rotation systems with different portions of nitrogen-fixing crops, intermediate crops, and organic fertilizers on the enzymatic activity and humus content of soils in organic farming was studied. The highest activity of the urease and invertase enzymes was determined in the soil under the crop rotation with 43% nitrogen-fixing crops and with perennial grasses applied twice per rotation. The application of manure and the growing of intermediate crops for green fertilizers did not provide any significant increase in the content of humus. The activity of urease slightly correlated with the humus content ( r = 0.30 at the significance level of 0.05 and r = 0.39 at the significance level of 0.01).

Environmental Assessment: Construct Airfield Lighting Vault and Demolish Building 531 at Grand Forks Air Force Base

DTIC Science & Technology

2007-08-01

The backfill material shall be free of bentonite, trash, frozen or organic material including lignites, humus , sod, grass, roots or other...organic material including lignites, humus , sod, grass, roots or other vegetation. The backfill material shall not be of a size greater than 3 inches, may...lignites, humus , sod, grass, roots or other vegetation. The backfill material shall not be of a size greater than 3 inches, may not contain more than 12

About soil cover heterogeneity of agricultural research stations' experimental fields

NASA Astrophysics Data System (ADS)

Rannik, Kaire; Kõlli, Raimo; Kukk, Liia

2013-04-01

Depending on local pedo-ecological conditions (topography, (geo) diversity of soil parent material, meteorological conditions) the patterns of soil cover and plant cover determined by soils are very diverse. Formed in the course of soil-plant mutual relationship, the natural ecosystems are always influenced to certain extent by the other local soil forming conditions or they are site specific. The agricultural land use or the formation of agro-ecosystems depends foremost on the suitability of soils for the cultivation of feed and food crops. As a rule, the most fertile or the best soils of the area, which do not present any or present as little as possible constraints for agricultural land use, are selected for this purpose. Compared with conventional field soils, the requirements for the experimental fields' soil cover quality are much higher. Experimental area soils and soil cover composition should correspond to local pedo-ecological conditions and, in addition to that, represent the soil types dominating in the region, whereas the fields should be as homogeneous as possible. The soil cover heterogeneity of seven arable land blocks of three research stations (Jõgeva, Kuusiku and Olustvere) was studied 1) by examining the large scale (1:10 000) digital soil map (available via the internet), and 2) by field researches using the transect method. The stages of soils litho-genetic and moisture heterogeneities were estimated by using the Estonian normal soils matrix, however, the heterogeneity of top- and subsoil texture by using the soil texture matrix. The quality and variability of experimental fields' soils humus status, was studied more thoroughly from the aspect of humus concentration (g kg-1), humus cover thickness (cm) and humus stocks (Mg ha-1). The soil cover of Jõgeva experimental area, which presents an accumulative drumlin landscape (formed during the last glacial period), consist from loamy Luvisols and associated to this Cambisols. In Kuusiku area, which landscape is characterized by till and limestone plains with thin Quaternary cover, the soil cover is more heterogeneous than in previous area. Kuusiku soil cover is more variegated by the soil texture and as well as by the genesis of soils. In addition to Cambisols, Leptosols, Gleysols and Luvisols may be found here as well. The dominating soils in Olustvere research area, which is situated on wavy upland plateau, are Albeluvisols.

Differential extraction of radiocarbon associated with soil biomass and humus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsao, C.W.; Bartha, R.

To detect the humification of organic compounds in soil that bypasses biomass incorporation, selective extraction procedures for radiocarbon from soil biomass and humus were evaluated. Following the incubation of [sup 14]C-glucose and [sup 14]C-benzoate in soil, fumigation--0.5 M K[sub 2]SO[sub 4] extraction and 0.15 M Na[sub 4]P[sub 2]O[sub 7] extraction selectively removed biomass-associated and humus-associated radiocarbon, respectively. Applying the recovery correction of 3.4[times] to biomass and 3.5[times] to humus, radiocarbon balances of 95 to 107% were obtained during a time window following the degradation of these substrates. Negligible overlap between the extractions renders the technique suitable for investigating the fatemore » of organics that, through cometabolism, attain unusual radiocarbon distributions in soil.« less

Energy: the Sun and economics. [Adverse effects of commercial fertilizer overuse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larson, A.H.

The Second Law of Thermodynamics is used to explain the scattering and dispersement of energy in the universe and the reordering of this energy through photosynthesis and the food chain. Plants are able to store energy in concentrated forms. Some of this stored energy is further concentrated when the plants are eaten by animals and some is scattered as waste. The accumulated soil and humus is considered an energy ''savings account'' along with fossil fuels. Using the bank account analogy, the earth can be said to be going bankrupt if it is consuming more energy than it is receiving. Themore » overuse of fossil fuels is more readily grasped than the idea that we are using up our humus. Farmers, who use fertilizers to replace the humus used up by growing plants, have shifted from the use of manure and natural humus to chemical fertilizers and pesticides (by-products of fossil fuels). This trend has left the soil humus-poor and the balance of nature disturbed. As the soil is depleted, food quality deteriorates in spite of increased fertilizers. More-efficient use of sewage as a fertilizer is recommended to reverse this process. (DCK)« less

Combustion of anaerobically digested humus as a fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kayhanian, M.; Jenkins, B.M.; Baxter, L.L.

Two pilot scale combustion experiments were conducted to explore the application of an anaerobically digested humus as fuel for commercial boilers. The experiments were performed in a fluidized bed combustor (FBC) and a multifuel suspension combustor (MFC). The results obtained indicate that the humus, blended with another conventional fuel (e.g., wood), can be used as a fuel in commercial boilers. Preliminary results of ash deposit analyses from the MFC indicate that the rate of deposition was low compared to high fouling biomass fuels such as straws, and similar to deposits obtained from wood.

Antimalarial activity of Bidens pilosa L. (Asteraceae) ethanol extracts from wild plants collected in various localities or plants cultivated in humus soil.

PubMed

Andrade-Neto, Valter F; Brandão, Maria G L; Oliveira, Francielda Q; Casali, Vicente W D; Njaine, Brian; Zalis, Mariano G; Oliveira, Luciana A; Krettli, Antoniana U

2004-08-01

Bidens pilosa (Asteraceae), a medicinal plant used worldwide, has antimalarial activity as shown in previous work. This study tested ethanol extracts from wild plants collected in three different regions of Brazil and from plants cultivated in various soil conditions. The extracts were active in mice infected with P. berghei: doses of < or =500 mg/kg administered by oral route reduced malaria parasitaemia and mouse mortality; higher doses were found to be less effective. Tested in vitro against three P. falciparum isolates, two chloroquine resistant and one mefloquine resistant, the plants cultivated under standard conditions, and in humus enriched soil, were active; but the wild plants were the most active. Analysis using thin layer chromatography demonstrated the presence of flavonoids (compounds considered responsible for the antimalarial activity) in all plants tested, even though at different profiles. Because B. pilosa is proven to be active against P. falciparum drug-resistant parasites in vitro, and in rodent malaria in vivo, it is a good candidate for pre-clinical tests as a phytotherapeutic agent or for chemical isolation of the active compounds with the aim of finding new antimalarial drugs. Copyright (c) 2004 John Wiley & Sons, Ltd.

Mechanisms for Reduction of Natural Waters Technogenic Pollution by Metals due to Complexions with Humus Substances (Zoning: Western Siberia and the European Territory of Russia)

NASA Astrophysics Data System (ADS)

Dinu, M. I.

2017-11-01

The article described the complexation of metal ions with humus substances in natural waters (small lakes). Humus substances as the major biochemical components of natural water have a significant impact on the forms and migration of metals and the toxicity of natural objects. This article presents the results of large-scale chemical experiments: the study of the structural features (zonal aspects) of humus substances extracted from soil and water natural climatic zones (more than 300 objects) in Russia (European Russia and West Siberia); the influence of structural features on the physic-chemical parameters of humus acids and, in particular, on their complexing ability. The functional specifics of humus matter extracted from soils is estimated using spectrometric techniques. The conditional stability constants for Fe(III), Cu(II), Pb(II), Cd(II), Zn(II), Ni(II), Co(II), Mn(II), Cr(III), Ca(II), Mg(II), Sr(II), and Al(III) are experimentally determined with the electrochemical, spectroscopic analysis methods. The activities of metals are classified according to their affinity to humus compounds in soils and water. The determined conditional stability constants of the complexes are tested by model experiments, and it is demonstrated that Fe and Al ions have higher conditional stability constants than the ions of alkali earth metals, Pb, Cu, and Zn. Furthermore, the influence of aluminium ions and iron on the complexation of copper and lead as well as the influence of lead and copper on complexation of cobalt and nickel have been identified. The metal forms in a large number of lakes are calculated basing on the experiments’ results. The main chemical mechanisms of the distribution of metals by forms in the water of the lakes in European Russia and West Siberia are described.

Carbon emission from the soil surface in a mature blueberry pine forest of the middle taiga (Republic of Komi)

NASA Astrophysics Data System (ADS)

Osipov, A. F.

2016-08-01

Data on the input of plant falloff and organic matter decomposition on the surface of the peaty podzolic-gleyic humus-illuvial (Gleyic Podzol) soil under a mature blueberry pine forest in the middle taiga are presented. The fractional composition of the falloff was determined, and constants of decomposition for its components were calculated. The carbon flux to the atmosphere due to the mineralization of plant residues is estimated at 251 g/m2. A close positive correlation ( r = 0.71; P < 0.05) was found between the carbon dioxide emission measured using a gas analyzer and the soil temperature at the depth of 10 cm. The CO2 emission for a growing period calculated from the data on its dependence on soil temperature in different years varied from 243 to 313 g C/m2 and was related to weather conditions.

Assessment of Composting Feasibility at Army Installations

DTIC Science & Technology

2008-09-01

The end product is a contaminant-free humus that can enhance landscaping and horticultural applications. Composting costs considerably less than...grasses, flowers, and trees by becoming the humus . Original wetland plants can be restored with the use of compost during planting. Compost provides

Effects of organic amendments on the toxicity and bioavailability of cadmium and copper in spiked formulated sediments

USGS Publications Warehouse

Besser, J.M.; Brumbaugh, W.G.; May, T.W.; Ingersoll, C.G.

2003-01-01

We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of both Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 ??g Cd/g and 493 ??g Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.

Effects of organic amendments on the toxicity and bioavailability of cadmium and copper in spiked formulated sediments.

PubMed

Besser, John M; Brumbaugh, William G; May, Thomas W; Ingersoll, Christopher G

2003-04-01

We evaluated the partitioning and toxicity of cadmium (Cd) and copper (Cu) spiked into formulated sediments containing two types of organic matter (OM), i.e., cellulose and humus. Amendments of cellulose up to 12.5% total organic carbon (TOC) did not affect partitioning of Cd or Cu between sediment and pore water and did not significantly affect the toxicity of spiked sediments in acute toxicity tests with the amphipod Hyalella azteca. In contrast, amendments of natural humus shifted the partitioning of hoth Cd and Cu toward greater concentrations in sediment and lesser concentrations in pore water and significantly reduced toxic effects of both metals. Thresholds for toxicity, based on measured metal concentrations in whole sediment, were greater for both Cd and Cu in sediments amended with a low level of humus (2.9% TOC) than in sediments without added OM. Amendments with a high level of humus (8.9% TOC) eliminated toxicity at the highest spike concentrations of both metals (sediment concentrations of 12.4 microg Cd/g and 493 microg Cu/g). Concentrations of Cd in pore water associated with acute toxicity were similar between sediments with and without humus amendments, suggesting that toxicity of Cd was reduced primarily by sorption to sediment OM. However, toxic effects of Cu in humus treatments were associated with greater pore-water concentrations than in controls, suggesting that toxicity of Cu was reduced both by sorption and by complexation with soluble ligands. Both sorption and complexation by OM tend to make proposed sediment quality guidelines (SQGs) based on total metal concentrations more protective for high-OM sediments. Our results suggest that the predictive ability of SQGs could be improved by models of metal interactions with natural OM in sediment and pore water.

Studies to determine whether underground waters in Wielkopolska Region (Poland) containing humus substances are suitable for practical purposes.

PubMed

Latour, Teresa; Drobnik, Michał; Sziwa, Danuta

2015-01-01

Water derived from Miocene aquifer in Wielkopolska region (Poland) has a 'brown-black' colouration resulting from humus substances. Because this colour is difficult to remove, such water is considered unfit for human consumption. The presence of naturally occurring humus acids with known biochemical properties may however lend such water for use in medicine, cosmetics or agriculture. To determine and evaluate the properties of 'brown-black' Miocene waters from analysing their physico-chemistry properties, mineral content and the presence and structures of humus acids. The test material was 4 samples of intensely coloured 'brown-black' underground waters from Miocene aquifer taken from the Greater Poland region at different locations; Obrzycko and Braczewo (both by Szamotuly), Sepno (by Koscian) and in Poznan (Szkolna Street). The water type was HCO3-Cl-Na with dissolved minerals ranging at concentrations of 828.5 mg/dm³ (Poznan) to 1600.5 mg/dm³ (Obrzycko). Fluorides were present at 0.71 mg/dm³ (Poznan) to 1.41 mg/dm³ (Braczewo) whilst iron (II) (ferrous ion) ranged from >10 mg/dm³ (Obrzycko) to 22.7 mg/dm³ (Sepno). Levels of humus acids varied between 188.6 mg/dm³ (Sepno) to 1501.8 mg/dm³ (Obrzycko) with predomination humic acids over hymatomelanic acids by factors from 1.³ to 10.6. Due to the test water's mineral content, which includes significant levels of iron II, fluoride and humus acids (>50 mg/dm³), it is suggested that it has therapeutic value and is suitable for medicinal bath treatments and in manufacturing medical products or cosmetics.

Boreal coniferous forest density leads to significant variations in soil physical and geochemical properties

NASA Astrophysics Data System (ADS)

Bastianelli, Carole; Ali, Adam A.; Beguin, Julien; Bergeron, Yves; Grondin, Pierre; Hély, Christelle; Paré, David

2017-07-01

At the northernmost extent of the managed forest in Quebec, Canada, the boreal forest is currently undergoing an ecological transition between two forest ecosystems. Open lichen woodlands (LW) are spreading southward at the expense of more productive closed-canopy black spruce-moss forests (MF). The objective of this study was to investigate whether soil properties could distinguish MF from LW in the transition zone where both ecosystem types coexist. This study brings out clear evidence that differences in vegetation cover can lead to significant variations in soil physical and geochemical properties.Here, we showed that soil carbon, exchangeable cations, and iron and aluminium crystallinity vary between boreal closed-canopy forests and open lichen woodlands, likely attributed to variations in soil microclimatic conditions. All the soils studied were typical podzolic soil profiles evolved from glacial till deposits that shared a similar texture of the C layer. However, soil humus and the B layer varied in thickness and chemistry between the two forest ecosystems at the pedon scale. Multivariate analyses of variance were used to evaluate how soil properties could help distinguish the two types at the site scale. MF humus (FH horizons horizons composing the O layer) showed significantly higher concentrations of organic carbon and nitrogen and of the main exchangeable base cations (Ca, Mg) than LW soils. The B horizon of LW sites held higher concentrations of total Al and Fe oxides and particularly greater concentrations of inorganic amorphous Fe oxides than MF mineral soils, while showing a thinner B layer. Overall, our results show that MF store three times more organic carbon in their soils (B+FH horizons, roots apart) than LW. We suggest that variations in soil properties between MF and LW are linked to a cascade of events involving the impacts of natural disturbances such as wildfires on forest regeneration that determines the vegetation structure (stand density) and composition (ground cover type) and their subsequent consequences on soil environmental parameters (moisture, radiation rate, redox conditions, etc.). Our data underline significant differences in soil biogeochemistry under different forest ecosystems and reveal the importance of interactions in the soil-vegetation-climate system for the determination of soil composition.

Altitude profiles of total chlorinated paraffins in humus and spruce needles from the Alps (MONARPOP).

PubMed

Iozza, Saverio; Schmid, Peter; Oehme, Michael; Bassan, Rodolfo; Belis, Claudio; Jakobi, Gert; Kirchner, Manfred; Schramm, Karl-Werner; Kräuchi, Norbert; Moche, Wolfgang; Offenthaler, Ivo; Weiss, Peter; Simoncic, Primoz; Knoth, Wilhelm

2009-12-01

Chlorinated paraffins (CPs) are toxic, bioaccumulative, persistent, and ubiquitously present in the environment. CPs were analyzed in humus and needle samples, which were taken within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) at sampling sites of 7 different altitude profiles in the Alps. Gas chromatography combined with electron ionization tandem mass spectrometry (EI-MS/MS) was used for the determination of total CPs (sum of short, medium and long chain CPs). CPs were found in all samples; the concentrations varied between 7 and 199 ng g(-1) dry weight (dw) and within 26 and 460 ng g(-1) dw in humus and needle samples, respectively. A clear vertical tendency within the individual altitude profiles could not be ascertained. Within all altitude profiles, elevated concentrations were observed in humus samples taken between 700 and 900 m and between 1300 and 1500 m. In the needle samples no similar correlation could be observed due to higher variation of the data.

Humus-reducing microorganisms and their valuable contribution in environmental processes.

PubMed

Martinez, Claudia M; Alvarez, Luis H; Celis, Lourdes B; Cervantes, Francisco J

2013-12-01

Humus constitutes a very abundant class of organic compounds that are chemically heterogeneous and widely distributed in terrestrial and aquatic environments. Evidence accumulated during the last decades indicating that humic substances play relevant roles on the transport, fate, and redox conversion of organic and inorganic compounds both in chemically and microbially driven reactions. The present review underlines the contribution of humus-reducing microorganisms in relevant environmental processes such as biodegradation of recalcitrant pollutants and mitigation of greenhouse gases emission in anoxic ecosystems, redox conversion of industrial contaminants in anaerobic wastewater treatment systems, and on the microbial production of nanocatalysts and alternative energy sources.

High Flux, Fouling Resistant Membranes for RO Pretreatment

DTIC Science & Technology

2012-05-31

formed by decomposition of dead organisms (often termed humus ) and carried to surface and seawater with rain water drainage. The most important...formulation, NOM components are introduced by Orchid Pro, which is a plant food formulation made from humus deposits. Blue-green algae is used as a

Stages of the development of alluvial soils in the Bikin River valley (the Amur River basin) in the Middle and Late Holocene

NASA Astrophysics Data System (ADS)

Nazarkina, A. V.; Belyanin, P. S.

2014-05-01

The evolution of alluvial soils in the Bikin River basin in the Middle and the Late Holocene is discussed. On the basis of biostratigraphic data, four pollen zones have been identified in the soils: Pinus koraiensis- Picea, Pinus koraiensis- Quercus- Sphagnum, Betula- Alnus- Alnaster, and Quercus. A set of soil characteristics (texture, acid-base properties, and the organic matter content and group composition) have also been determined. These data allow us to distinguish between four stages of alluvial soil formation in the Bikin River basin. They characterize humus-forming conditions in the Middle and the Late Holocene. Reconstruction of ancient vegetation conditions makes it possible to conclude that climatic fluctuations were synchronous with changes in the soil characteristics. During the Holocene climatic optimum, humus was formed in a slightly acid medium, and humic acids predominated. In cold periods with increased precipitation, fulvic acids predominated in the composition of humus, and the portion of insoluble residue was high because of the more acid medium. The stages of alluvial pedogenesis in the Bikin River valley follow the sedimentation model of soil evolution. Alluvial gray humus soils evolved from typical gray humus soils under meadow communities during warm periods to gleyic and gleyed soils under birch shrubs and alder groves in colder and wetter periods.

Experimenting with Different Bulking Agents in an Aerobic Food Waste Composter

NASA Astrophysics Data System (ADS)

Chann, S.

2016-12-01

With one third of Hong Kong's solid wastage being food scraps, reducing food waste has become crucial. The ISF Academy, a Hong Kong private school, had an A900 Rocket Food Composter installed in 2013, hoping to reduce its carbon footprint. The 27 metric tons of food wastage produced annually by the school is put through an aerobic process and the wastage is converted into humus. The composter has a capacity of 1750 litres of food and it produces humus every 14 days. The base of the humus consists of a bulking agent and food waste (2:1). A bulking agent is a carbon based material used to absorb moisture and odors, add structure and air and eliminate bugs from humus. This study contains comparative data on a few of the listed bulking agents: Hemp, Kenaf, rapeseed oil straw, miscanthus and shredded cardboard. The aim of this study is to determine an alternative reliable, affordable and suitable bulking agent to wood shavings: the current agent used. The humus produced must pass regulations for "general agricultural use" as it is used for experiential learning and gardening with primary school students. Over 500 children are participating in the school's plantation project, producing legumes for the school cafeteria. ISF pioneers and sets an example for other Hong Kong schools, showing that a composting and plantation scheme, not only proves to have environmental benefits but also educational uses.

Biodegradation of RDX by Stimulating Humic Substance- and Fe(III) - Reduction

DTIC Science & Technology

2007-06-19

Sediments with Quinones and Humus as Terminal Electron Acceptors. Appl. Environ. Microbiol. 67:4471-4478. 10. Coates, J. D., D. J. Ellis, E. L...167. 57. Stevenson, F. J. 1982. Humus chemistry genesis, composition, reactions. Wiley Interscience, New York. 58. Stolz, J. F., D. R. Lovley, and

Estonian soil classification as a tool for recording information on soil cover and its matching with local site types, plant covers and humus forms classifications

NASA Astrophysics Data System (ADS)

Kõlli, Raimo; Tõnutare, Tõnu; Rannik, Kaire; Krebstein, Kadri

2015-04-01

Estonian soil classification (ESC) has been used successfully during more than half of century in soil survey, teaching of soil science, generalization of soil databases, arrangement of soils sustainable management and others. The Estonian normally developed (postlithogenic) mineral soils (form 72.4% from total area) are characterized by mean of genetic-functional schema, where the pedo-ecological position of soils (ie. location among other soils) is given by means of three scalars: (i) 8 stage lithic-genetic scalar (from rendzina to podzols) separates soils each from other by parent material, lithic properties, calcareousness, character of soil processes and others, (ii) 6 stage moisture and aeration conditions scalar (from aridic or well aerated to permanently wet or reductic conditions), and (iii) 2-3 stage soil development scalar, which characterizes the intensity of soil forming processes (accumulation of humus, podzolization). The organic soils pedo-ecological schema, which links with histic postlithogenic soils, is elaborated for characterizing of peatlands superficial mantle (form 23.7% from whole soil cover). The position each peat soil species among others on this organic (peat) soil matrix schema is determined by mean of 3 scalars: (i) peat thickness, (ii) type of paludification or peat forming peculiarities, and (iii) stage of peat decomposition or peat type. On the matrix of abnormally developed (synlithogenic) soils (all together 3.9%) the soil species are positioned (i) by proceeding in actual time geological processes as erosion, fluvial processes (at vicinity of rivers, lakes or sea) or transforming by anthropogenic and technological processes, and (ii) by 7 stage moisture conditions (from aridic to subaqual) of soils. The most important functions of soil cover are: (i) being a suitable environment for plant productivity; (ii) forming adequate conditions for decomposition, transformation and conversion of falling litter (characterized by humus cover type); (iii) being compartment for deposition of humus, individual organic compounds, plant nutrition elements, air and water, and (iv) forming (bio)chemically variegated active space for soil type specific edaphon. For studying of ESC matching with others ecosystem compartments classifications the comparative analysis of corresponding classification schemas was done. It may be concluded that forest and natural grasslands site types as well the plant associations of forests and grasslands correlate (match) well with ESC and therefore these compartments may be adequately expressed on soil cover matrixes. Special interest merits humus cover (in many countries known as humus form), which is by the issue natural body between plant and soil or plant cover and soil cover. The humus cover, which lied on superficial part of soil cover, has been formed by functional interrelationships of plants and soils, reflects very well the local pedo-ecological conditions (both productivity and decomposition cycles) and, therefore, the humus cover types are good indicators for characterizing of local pedo-ecological conditions. The classification of humus covers (humus forms) should be bound with soil classifications. It is important to develop a pedocentric approach in treating of fabric and functioning of natural and agro-ecosystems. Such, based on soil properties, ecosystem approach to management and protection natural resources is highly recommended at least in temperate climatic regions. The sound matching of soil and plant cover is of decisive importance for sustainable functioning of ecosystem and in attaining a good environmental status of the area.

Humus and energy balances and greenhouse gas emissions with compost fertilization in organic farming compared with mineral fertilization

NASA Astrophysics Data System (ADS)

Erhart, Eva; Schmid, Harald; Hülsbergen, Kurt-Jürgen; Hartl, Wilfried

2015-04-01

Humus and energy balances and greenhouse gas emissions with compost fertilization in organic farming compared with mineral fertilization E. Erhart, H. Schmid, K.-J. Hülsbergen, W. Hartl The positive effects of compost fertilization on soil humus with their associated benefits for soil quality are well-established. The aim of the present study was to assess the effect of compost fertilization on humus and energy balances and greenhouse gas emissions and to compare the results of the humus balances with the changes in soil organic carbon contents measured in the soil of the experimental field. In order to assess the effects of compost use in organic farming as compared to conventional farming practice using mineral fertilizers, the field experiment with compost fertilization 'STIKO' was set up in 1992 near Vienna, Austria, on a Molli-gleyic Fluvisol. It included three treatments with compost fertilization (C1, C2 and C3 with 8, 14 and 20 t ha-1 y-1 f. m. on average of 14 years), three treatments with mineral nitrogen fertilization (N1, N2 and N3 with 29, 46 and 63 kg N ha-1 y 1 on average) and an unfertilized control (0) in six replications in a latin rectangle design. In the field trial, biowaste compost from the composting plant of the City of Vienna was used. Data from the field experiment (from 14 experimental years) were fed into the model software REPRO to calculate humus and energy balances and greenhouse gas emissions. The model software REPRO (REPROduction of soil fertility) couples the balancing of C, N and energy fluxes. For the determination of the net greenhouse effect, REPRO performs calculations of C sequestration in the soil, CO2 emissions from the use of fossil energy and N2O emissions from the soil. Humus balances showed that compost fertilization at a rate of 8 t ha-1 y-1 (C1) resulted in a positive humus balance of +115 kg C ha-1 y-1. With 14 and 20 t ha-1 y-1 compost (C2 and C3), respectively, humus accumulated at rates of 558 and 1021 kg C ha-1 y-1. With mineral fertilization at rates of 29 - 63 kg N ha-1 y-1 (N1 - N3), balances were moderately negative ( 169 to -227 kg C ha-1 y-1), while a clear humus deficit of 457 kg C ha-1 y-1 showed in the unfertilized control. Compared with measured soil organic carbon data REPRO predicted soil organic carbon contents fairly well with the exception of the treatments with high compost rates. Here REPRO clearly overestimated soil organic carbon contents for this site. Energy efficiency, as described by the output/input ratio, was highest in the control, followed by C1. Mineral fertilization treatment N3 was most energy intensive. The greenhouse gas balance indicated net carbon sequestration already with medium compost rates (C2), and net carbon sequestration of 1700 kg CO2-eq ha-1 y-1 in C3. Mineral fertilization yielded net greenhouse gas emissions of around 2000 kg CO2-eq ha-1 y 1. The highest greenhouse gas emissions had the unfertilized control due to the degradation of soil organic matter and lowest organic matter input. These findings underline that compost fertilization holds a high potential for carbon sequestration and for the reduction of greenhouse gas emissions.

Experimental evidence of large changes in terrestrial chlorine cycling following altered tree species composition.

PubMed

Montelius, Malin; Thiry, Yves; Marang, Laura; Ranger, Jacques; Cornelis, Jean-Thomas; Svensson, Teresia; Bastviken, David

2015-04-21

Organochlorine molecules (Clorg) are surprisingly abundant in soils and frequently exceed chloride (Cl(-)) levels. Despite the widespread abundance of Clorg and the common ability of microorganisms to produce Clorg, we lack fundamental knowledge about how overall chlorine cycling is regulated in forested ecosystems. Here we present data from a long-term reforestation experiment where native forest was cleared and replaced with five different tree species. Our results show that the abundance and residence times of Cl(-) and Clorg after 30 years were highly dependent on which tree species were planted on the nearby plots. Average Cl(-) and Clorg content in soil humus were higher, at experimental plots with coniferous trees than in those with deciduous trees. Plots with Norway spruce had the highest net accumulation of Cl(-) and Clorg over the experiment period, and showed a 10 and 4 times higher Cl(-) and Clorg storage (kg ha(-1)) in the biomass, respectively, and 7 and 9 times higher storage of Cl(-) and Clorg in the soil humus layer, compared to plots with oak. The results can explain why local soil chlorine levels are frequently independent of atmospheric deposition, and provide opportunities for improved modeling of chlorine distribution and cycling in terrestrial ecosystems.

Vegetation/soil distribution of semivolatile organic compounds in relation to their physicochemical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weiss, P.

The concentrations (C) of several semivolatile organic compounds (SOCs) in Norway spruce needles (N) and in the local humus horizon (O) of 25 remote Austrian forest sites were used to calculate an ecosystem-oriented partition coefficient needles/humus horizon (C{sub N}/C{sub O}). Between 66 and 78% of the compounds' variation of this quotient could be explained by each of the following physicochemical parameters: vapor pressure (p{sub s}) and the partition coefficients n-octanol/water (K{sub OW}), n-octanol/air (K{sub OA}), and adsorbed/ dissolved in soil (K{sub OC}) of the compounds. This result further underlines the usefulness of these parameters for predicting the behavior of SOCsmore » in terrestrial ecosystems. Compounds with low p{sub s} and high K{sub OW}, K{sub OA}, and K{sub OC} show a very low C{sub N}/C{sub O} quotient, which implies a higher accumulation of these compounds in the O horizon than in the needles. The role of forest soils as sink for these SOCs is demonstrated. Alternatively, C{sub N}/C{sub O} > 1, due to higher concentrations in the needles than in the O horizon, have been shown for SOCs with comparably high p{sub s} and low K{sub OW}, K{sub OA}, and K{sub OC}. In this respect, the possible role of revolatilization of the more volatile SOCs from soils to needles is discussed. In the mineral soil layers below the O horizon, SOCs with lower K{sub OC} and better water solubility tend to be less accumulated. However, if all investigated compounds are taken into consideration, accumulation in the mineral soil layers showed no general trend in relation to the selected physicochemical parameters.« less

Microbial biomass and basal respiration in Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

NASA Astrophysics Data System (ADS)

Abakumov, E.; Mukhametova, N.

2014-03-01

Antarctica is the unique place for pedological investigations. Soils of Antarctica have been studied intensively during the last century. Antarctic logistic provides the possibility to scientists access the terrestrial landscapes mainly in the places of polar stations. That is why the main and most detailed pedological investigations were conducted in Mc Murdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann hills and Schirmacher Oasis. Investigations were conducted during the 53rd and 55th Russian Antarctic expeditions on the base of soil pits and samples collected in Sub-Antarctic and Antarctic regions. Soils of diverse Antarctic landscapes were studied with aim to assess the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. The investigation conducted shows that soils of Antarctic are quite different in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as the upper organic layer. The most developed organic layers were revealed in peat soils of King-George Island, where its thickness reach even 80 cm. These soils as well as soils under guano are characterized by the highest amount of total organic carbon (TOC) 7.22-33.70%. Coastal and continental soils of Antarctic are presented by less developed Leptosols, Gleysols, Regolith and rare Ornhitosol with TOC levels about 0.37-4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones which can be interpreted as result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. Also the soils of King-George island have higher portion of microbial biomass (max 1.54 mg g-1) than coastal (max 0.26 mg g-1) and continental (max 0.22 mg g-1) Antarctic soils. Sub-Antarctic soils mainly differ from Antarctic ones in increased organic layers thickness and total organic carbon content, higher microbial biomass carbon content, basal respiration and metabolic activity levels.

Two factors defining humus as a key structural component of soil organic matter and as a physicochemical speciation of carbon in its turnover wending its way through the micro environment of soil, sediments and natural waters

NASA Astrophysics Data System (ADS)

Aleksandrova, Olga

2016-04-01

Over the last 40-50 years, the scientific community started to question the model of soil organic matter. Close consideration has been given to the following models: the classic model that regards a significant part of soil organic matter as large, covalently bonded 'humus polymers', which are formed via "humification", and the continuum model that considers soil organic matter as 'supra molecular aggregates of degradation fragments'[1]. The underlying cause of a contradiction between 'humus polymers' model and continuum model of SOM implies that 'the vast majority of operationally defined humic material in soils is a very complex mixture of microbial and plant biopolymers and their degradation products but not a distinct chemical category'. Furthermore, authors [1] of the continuum model suggested 'to turn to modern, evidence based concept, and to abandon the operational proxies of the past' that means to consider term 'humus' as an out-of-date model. However, micro cosmos of organic matter in soil implies not only an assemblage of molecular units but also a system of interactions of different types [2]. Peculiar interactions in SOM allow us to understand a lot of physicochemical phenomena observed in soil samples, for example by EPR and SL EPR examinations [3, 4, 5]. Among specific interactions in soil, mention should be made of hydrogen (H) bonds and hydrophobic interaction. Spin Labeling EPR examination of natural and labeled soil samples showed that in SOM, there are stable and roaming H-bonds. Stable H-bonds are typical of a part of SOM, which can be isolated as humus, whereas a non-humified part of SOM is rich in roaming hydrogen bonds. Addition of some water (more than maximal moisture) to soil leads to disintegration of some weak H-bond. Other solvents influence SOM the same way but they disintegrate stronger or weaker H-bonds in dependence on used solvent. Thus in soil, different environmental conditions (like moisture, temperature or pollution) influence on a change in the partitioning of roaming H-bonds, and in turn, define components, into which non-humified SOM can be disintegrated. Therefore, some physicochemical species of SOM, which can be observed in physicochemical processes of carbon turnover in soil, originate from disintegrated SOM bulged at the seams of weak H-bonds, and doesn't reveal strong properties of humus because humus structure is still bound to SOM via stronger H-bonds. Also, SL EPR examination of native and labeled soil samples revealed the substantial influence of hydrophobic interaction on physicochemical speciation of carbon in soil, and this interaction is mediated by humus [3]. Among different effects of hydrophobic interaction, the formation of condensed matter is of great interest. Condensed matter mediated by humic acids is shown to reveal specific quantum properties and invoke hydrodynamic instability on the surface of plant roots that results in uptake of the whole nano-pieces of humus by plant roots, as it was observed in [6, 7]. Considered effects of H-bonds with different bonding energy and hydrophobic interaction in SOM show that a carbon turnover in soil is mediated by humus, and humus play a substantial role as the physicochemical speciation in carbon turnover. Thus, model of 'humus' is still an up-to-date model. 1.Lehmann J. &Kleber H. (2015). Nature, 528, Issue 7580, 60 - 68. 2. M. Hutta, R. Gora, R. Halko, et al., (2011). J. Chromatogr. A., 1218, 8946. 3. Alexanderova O.N. (2015). J Soils Sediments, DOI 10.1007/s11368-015-1195-2 4. Aleksandrova O.N., Kholodov V.A., Perminova I.V. (2015). Russian Journal of Physical Chemistry A, 2015, Vol. 89, No. 8, pp. 1407-1413. 5. Aleksandrova O.N. (2013). J Geochem Explor 129:6-13. 6. Smirnov A.I. et al. (1991). J. of Magnetic Resonance 91, 386-391 7. Kulikova N.V. et al. (2012). Conference HIT-2012.

Increased nitrogen availability counteracts climatic change feedback from increased temperature on boreal forest soil organic matter degradation

NASA Astrophysics Data System (ADS)

Erhagen, Bjorn; Nilsson, Mats; Oquist, Mats; Ilstedt, Ulrik; Sparrman, Tobias; Schleucher, Jurgen

2014-05-01

Over the last century, the greenhouse gas concentrations in the atmosphere have increased dramatically, greatly exceeding pre-industrial levels that had prevailed for the preceding 420 000 years. At the same time the annual anthropogenic contribution to the global terrestrial nitrogen cycle has increased and currently exceeds natural inputs. Both temperature and nitrogen levels have profound effects on the global carbon cycle including the rate of organic matter decomposition, which is the most important biogeochemical process that returns CO2 to the atmosphere. Here we show for the first time that increasing the availability of nitrogen not only directly affects the rate of organic matter decomposition but also significantly affects its temperature dependence. We incubated litter and soil organic matter from a long-term (40 years) nitrogen fertilization experiment in a boreal Scots pine (Pinus silvestris L.) forest at different temperatures and determined the temperature dependence of the decomposition of the sample's organic matter in each case. Nitrogen fertilization did not affect the temperature sensitivity (Q10) of the decomposition of fresh plant litter but strongly reduced that for humus soil organic matter. The Q10 response of the 0-3 cm soil layer decreased from 2.5±0.35 to an average of 1.9±0.21 over all nitrogen treatments, and from 2.2±0.19 to 1.6±0.16 in response to the most intense nitrogen fertilization treatment in the 4-7 cm soil layer. Long-term nitrogen additions also significantly affected the organic chemical composition (as determined by 13C CP-MAS NMR spectroscopy) of the soil organic matter. These changes in chemical composition contributed significantly (p<0.05) to the reduced Q10 response. These new insights into the relationship between nitrogen availability and the temperature sensitivity of organic matter decomposition will be important for understanding and predicting how increases in global temperature and rising anthropogenic nitrogen inputs will affect the global carbon cycle and the associated climatic feedback processes.

Evaluating Mineral-Associated Soil Organic Matter Pools as Indicators of Forest Harvesting Disturbance

NASA Astrophysics Data System (ADS)

Kellman, L. M.; Gabriel, C. E.

2015-12-01

Soil organic matter (SOM) in northern forest soils is associated with a suite of minerals that can confer SOM stability, resulting in the potential for long-term storage of carbon. Increasingly, evidence is suggesting that SOM in certain mineral phases is dynamic and vulnerable to soil disturbance. The objective of this research was to investigate changes in a suite of mineral-associated pools of SOM through depth in a temperate forest soil to determine which mineral-associated carbon pools are most sensitive to forest harvesting disturbance. Sequential selective dissolutions representing increasingly stable SOM pools (soluble minerals (deionized water); humus-mineral complexes (Na-pyrophosphate); poorly crystalline minerals (HCl hydroxylamine); and crystalline secondary minerals (Na-dithionite + HCl)) of mineral soils through depth to 50 cm were carried out in podzolic soils sampled from temperate red spruce forests of contrasting stand age in Nova Scotia, Canada. Results of this analysis point to a loss of carbon from SOM within the B-horizon of the most recently harvested site from the pyrophosphate-extracted humus mineral complexed SOM, suggesting that it is this exchangeable pool that appears to be destabilized following clearcut harvesting at these study sites. This suggests that recovery from this landuse disturbance is dependent upon increasing storage of this SOM pool, and that mineral-associated pools, particularly pyrophosphate-extractable SOM, may be a useful indicator of changes to soil carbon storage following land use change.

Dynamic response of woody vegetation on fencing protection in semi-arid areas; Case study: Pilot exclosure on the Firmihin Plateau, Socotra Island.

PubMed

Habrova, Hana; Pavlis, Jindrich

2017-02-01

Woody vegetation dynamics and Dracaena cinnabari regeneration have been studied for five years in the conditions of Socotra Island. Woody plants were measured regularly inside and outside the exclosure area, and the growth and survival of D. cinnabari seedlings were observed. In the exclosure of about 1000 m 2 a total of 49 species were identified, including 23 endemics, growing in the average density of 3.82 specimens per m 2 . The fenced area was overgrown relatively rapidly by dense grass cover - reaching approx. 2.7 t/ha. Species growth dynamics inside and outside the exclosure shows that grazing had a marked impact, leading to the elimination of trees and shrubs. All grazed species grew noticeably in the exclosure, in the average of 50 cm in 5 years. D. cinnabari as the dominant flagship species of Socotra has been studied with regards to regeneration dynamics. Observations indicate that probability of its seedlings survival increases with their age. No seedlings germinated from the seeds sown in the experiment, however, outplanted seedlings performed relatively well. Field observations show that D. cinnabari seed germination is triggered when the seed reaches a protected micro-habitat with a developed humus layer and high relative humidity in the soil lasts for at least two days.

MECHANISTIC ROLES OF SOIL HUMUS AND MINERALS IN THE SORPTION OF NONIONIC ORGANIC COMPOUNDS FROM AQUEOUS AND ORGANIC SOLUTIONS

EPA Science Inventory

Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral...

Environmental Assessment for Explosives Ordnance Disposal Proficiency Training Range at Wright-Patterson Air Force Base, Ohio

DTIC Science & Technology

2010-06-01

s) __ Test Plt(s) __ Test Trench(es) __ Deep Test(s) __ PZ or Humus Removal __ Testing/Excav. (strategy unknown) __ Mitigation/Block Excavation...Collection __ Surface Collection _Auger/Soil Corer _Shovel Test (s) .lL... Test Pit (s) _Test Trench (es) __ Deep Test (s) _ PZ or Humus Removal

Leaf fall, humus depth, and soil frost in a northern hardwood forest

Treesearch

George Hart; Raymond E. Leonard; Robert S. Pierce

1962-01-01

In the mound-and-depression microtopography of the northern hardwood forest, leaves are blown off the mounds and collect in the depressions. This influence of microtopography on leaf accumulation is responsible for much of the variation in humus depth; and this, in turn, affects the formation and depth of soil frost.

Soil humus and carbon popularity from 1804 (N. de Saussure) to 2015 (COP 21)

NASA Astrophysics Data System (ADS)

Feller, Christian; Brevik, Eric

2017-04-01

The popularity of humus (or soil organic matter SOM) and later on soil organic carbon (SOC) as related to plant nutrition, soil fertility and environment varied widely from the beginning of the 19th century with the research of Nicolas de Saussure (1804) to Thaer's humus theory (1809) followed by Liebig's mineral theory (1840) until the 20th century with new perceptions of the beneficial roles of SOM. Nowadays, it is known that SOM (with SOC) participates in multiple interactions with the other Earth ecosystem compartments (hydrosphere, biosphere, atmosphere lithosphere). Very recently SOM and SOC were raised to the summit of the international challenges concerning global changes with the French initiative entitled "4 per 1000". Therefore, from the past to the present humus has received varying levels of consideration regarding its benefits for humanity. The central questions of this presentation will be: 1) What were the links between science and society at each of these epistemological steps during these last 200 years, and 2) what were the scientific theories involved?

Carbon source and energy harvesting optimization in solid anolyte microbial fuel cells

NASA Astrophysics Data System (ADS)

Adekunle, Ademola; Raghavan, Vijaya; Tartakovsky, Boris

2017-07-01

This work investigates the application of a solid anolyte microbial fuel cell (saMFC) as a long-lasting source of electricity for powering electronic devices. Broadly available biodegradable materials such as humus, cattle manure, peat moss, and sawdust are evaluated as solid anolytes. The initial comparison shows significantly higher power production in the saMFC operated using humus as compared to other solid anolytes. At the same time, power production in the humus-based saMFC is found to decline after about 40 days of operation, while the sawdust MFC demonstrates stable performance over the test period. Following this initial comparison, a combined humus - sawdust anolyte is developed to increase saMFC life span. The optimized saMFC demonstrates stable power production for over nine months. Furthermore, power production in the saMFC is maximized by using an intermittent connection to an electrical load (on/off operation) and optimizing the connection/disconnection times. These results demonstrate the feasibility of utilizing solid anolytes for developing inexpensive and long-lasting biobatteries operated on renewable carbon sources.

Quantification of rock slope terrain properties

NASA Astrophysics Data System (ADS)

Volkwein, Axel; Gerber, Werner

2017-04-01

Rockfall trajectory simulation codes need information on the terrain properties to formulate appropriate rebound models. Usually, the manuals of rockfall simulation codes give sketches or photographs of terrain samples [1,2]. Based on these the user can select suitable terrains for the simulation area. We now would like to start a discussion whether it is possible to numerically quantify the terrain properties which would make the ground assignment more objective. Different ground properties play a role for the interaction between a falling rock and the ground: • Elastic deformation • plastic deformation • Energy absorption • friction • hardness • roughness • surface vs. underground • etc. The question is now whether it is possible to quantify above parameters and to finally provide tables that contain appropriate simulation parameters. In a first attempt we suggest different methods or parameters that might be evaluated in situ: • Small scale drop tests • Light weight deflectometer (LWD) • Particle sizes • Sliding angle • Particle distribution • Soil cover • Water content Of course, above measurements will never perfectly fit to different mountain slopes. However, if a number of measurements has been made their spreading will give an idea on the natural variability of the ground properties. As an example, the following table gives an idea on how the ME and Evd values vary for different soils. Table 1: LWD measurements on different soil types [3] Ground type Soil layer Soil humidityEvd (median)σ (median)Evd (average) Humus-carb. < 10cm dry 17.4 6.8 15.6 Regosol 10 - 30cm dry 8.6 3.9 9.4 Brownish 30 - 50cm dry 12.1 3.2 11.7 Calcaric 30 - 50cm dry 7.5 3.3 7.0 Acid brownish70 - 100cmdry 7.8 2.1 7.7 Fahlgley 10 - 30cm dry 9.2 4.0 7.7 References [1] Bartelt P et al (2016) RAMMS::rockfall user manual v1.6. SLF, Davos. [2] Dorren L.K.A., 2015. Rockyfor3D (v5.2) revealed - Transparent description of the complete 3D rockfall model. ecorisQ paper (www.ecorisq.org): 32 p. [3] Hoffmann P. (2015) Härte von Böden. Bsc thesis, ZHAW Waedenswil.

Decreasing Toxic Metal Bioavailability with Novel Soil Amendment Strategies

DTIC Science & Technology

2007-05-01

approach with loading levels designed for scale-up to the field. Loading levels for humus or sphagnum moss will be 0.5, 1.0, and 5.0 % w/w. Such...treatment strategies are economical for implementing at the field scale. Premium grade humus or sphagnum moss cost $0.10 per kg which suggests treating a

Long-term effects of conventional and reduced tillage systems on soil condition and yield of maize

NASA Astrophysics Data System (ADS)

Rátonyi, Tamás; Széles, Adrienn; Harsányi, Endre

2015-04-01

As a consequence of operations which neglect soil condition and consist of frequent soil disturbance, conventional tillage (primary tillage with autumn ploughing) results in the degradation and compaction of soil structure, as well as the reduction of organic matter. These unfavourable processes pose an increasing economic and environmental protection problem today. The unfavourable physical condition of soils on which conventional tillage was performed indicate the need for preserving methods and tools. The examinations were performed in the multifactorial long-term tillage experiment established at the Látókép experiment site of DE MÉK. The experiment site is located in the Hajdúság loess ridge (Hungary) and its soil is loess-based calcareous chernozem with deep humus layer. The physical soil type is mid-heavy adobe. The long-term experiment has a split-split plot design. The main plots are different tillage methods (autumn ploughing, spring shallow tillage) without replication. In this paper, the effect of conventional and reduced (shallow) tillage methods on soil conditions and maize yield was examined. A manual penetrometer was used to determine the physical condition and compactedness of the soil. The soil moisture content was determined with deep probe measurement (based on capacitive method). In addition to soil analyses, the yield per hectare of different plots was also observed. In reduced tillage, one compacted layer is shown in the soil resistance profile determined with a penetrometer, while there are two compacted layers in autumn ploughing. The highest resistance was measured in the case of primary tillage performed at the same depth for several years in the compacted (pan disk) layer developed under the developed layer in both treatments. The unfavourable impact of spring shallow primary tillage on physical soil conditions is shown by the fact that the compaction of the pan disk exceed the critical limit value of 3 MPa. Over the years, further deterioration of physical conditions were observed below the regularly cultivated layer. In shallow tillage, soil contained more moisture (at 40-50 cm deep and below) than in the ploughed treatment. There are multiple reasons for this phenomenon. This tillage method is moisture preserving as the depth of disturbance (15 cm) is lower than in ploughed treatments (25-30 cm). Soil surface is covered by stem residues after sowing, which may reduce the extent of evaporation. The soil surface CO2 emission was determined based on primary tillage depth, intensity and the period which passed since primary tillage. Spring shallow primary tillage resulted in higher CO2 emission than conventional tillage. The average maize yield was significantly higher in the autumn ploughing treatment (6,6-13,9 t/ha) in the first half (7 years) of the examined period (2000-2014). Higher average yields were observed in two years in the spring shallow tillage treatment and no significant yield difference was observed between tillage treatments in other examined years. Reduced (shallow) tillage increases the risk of near-surface soil compaction and the biological activity of the soil, while it reduces the moisture loss of the soil. Reducing tillage intensity does not necessarily reduce the average yield of the produced crop (maize).

Selectivity sequences and sorption capacities of phosphatic clay and humus rich soil towards the heavy metals present in zinc mine tailing.

PubMed

Chaturvedi, Pranav Kumar; Seth, Chandra Shekhar; Misra, Virendra

2007-08-25

Sorption efficacy of phosphatic clay and humus rich soil alone and on combination were tested towards heavy metals present in zinc mine tailing (Zawar Zinc Mine), Udaipur (India). Characterization of the zinc mine tailing sample indicated the presence of Pb, Cu, Zn and Mn in the concentration of 637, 186, 720 and 577microg(-1), respectively. For sorption efficacy, the zinc mine tailing soil were properly amended with phosphatic clay and humus rich soil separately and in combination and leachability study was performed by batch experiment at different pH range from 3 to 9. The data showed that the percent leachability of heavy metal in non-amended soil was 75-90%. After amendment with phosphatic clay percent leachability of heavy metals became 35-45%. Further, the addition of humus soil to phosphatic clay decreased the percent leachability up to 5-15% at all tested pH. Column leachability experiment was performed to evaluate the rate of leachability. The shape of cumulative curves of Pb, Cu, Zn and Mn showed an increase in its concavity in following order: PbCu>Zn>Mn. Further, Langmuir isotherms applied for the sorption studies indicated that phosphatic clay in the presence of humus soil had high affinity for Pb followed by Cu, Zn and Mn, with sorption capacities (b) 139.94, 97.02, 83.32 and 67.58microgg(-1), respectively.

Growth Response of Seedling Yellow Birch to Humus-Soil Mixtures

Treesearch

Carl H. Tubbs; Robert R. Oberg

1966-01-01

Previous observations of the establishment of yellow birch have cited the importance of mixed humus-mineral soil seedbeds. Godman and Krefting pointed out that both germination and growth were enhanced. Subsequent studies have shown that while germination in the absence of competition is adequate on mineral soil of a Podzol A under a wide variety of light and...

Assessment of environmental stability of agroserous soil according to indicator of energy potential of organic substances

NASA Astrophysics Data System (ADS)

Murtazina, S. G.; Gaffarova, L. G.; Murtazin, MG

2018-01-01

Studies of the group and fractional composition of humus have determineded that the long-term use of soil (for 20 years) without the use of fertilizers (control) leads to a decrease in the content of humic acids and fulvic acids relative to the initial soil, which indicates an increase in mineralization of the soil humus. Under the influence of a long application of high doses of mineral fertilizers, the content of mobile fractions of humic and fulvic acids in the field rotation increases in the humus content. In systems of agriculture that are not balanced by organic matter, which are predominant in most farms of the Republic of Tatarstan, the use of very high doses of potassium fertilizers is not justified energetically. To compensate for losses of humus and its energy potential in calculating organic fertilizers on backgrounds with high doses of mineral fertilizers, the humification coefficients of organic residues should be increased by 30-40% during the rotational period of 5-6 years, which will reduce the loss of energy reserves and thereby improve the ecological stability of soils and the stability of agricultural landscapes

Effect of Contrasting Trophic Conditions on the Priming Effect in Gray Forest Soils

NASA Astrophysics Data System (ADS)

Zhuravleva, A. I.; Alifanov, V. M.; Blagodatskaya, E. V.

2018-02-01

Priming effects initiated by the addition of 14C glucose have been compared for humus horizons of soils existing under continuous input of fresh organic substrates and for buried soil horizons, in which entering of organic matter has been essentially limited. The effect of microrelief on the manifestation of priming effect in the humus horizons of gray forest soil on microhigh and in microlow has been estimated. Humus horizon in soils on microhigh, not activated by glucose, produced two times more CO2 in comparison with soils of microlow. However, the introduction of glucose canceled the effect of microrelief on CO2 emission. The intensity of absolute priming effect correlated with the Corg pool, initial microbial biomass, and enzyme activity, decreasing from humus horizons to the buried ones, and did not depend on microrelief. The effect of microrelief was observed, when assessing the priming effect relative to control (soil not activated by glucose): the value of relative priming effect was 1.5 times greater in A horizon of gray forest soil in microlow in comparison with that on microhigh being the result of increasing activity of enzymes.

The change of soil properties after wildfires in drained peatlands (Moscow region, Russia)

NASA Astrophysics Data System (ADS)

Koshovskii, Timur; Tsibart, Anna; Smirnova, Maria; Valentina, Gavrilova; Anna, Kiseleva

2014-05-01

The peat fires differ from the forest and grassland fires, because the soil organic matter acts as burning material. The deep peat horizons are heated or burned during smoldering fires, causing the dramatic change in soil properties. But the most of available data are devoted to changes in organo-mineral soils. In addition, the alteration in hydrological regime, for instance drainage, makes landscapes and soils very vulnerable to wildfires. Drained peatlands are widespread in the European part of Russia and they are affected to extreme wildfires of 2010. So there is a need of post-fire peat soils investigations in this region. During current research the soils of drained peatlands of Moscow Region (Russia) subjected to wildfires of 2002 and 2010 were studied. A total of 14 profiles including background and post-pyrogenic histosols and histic podsols were investigated. Soil samples were taken from genetic horizons and from every 10 cm in cases of thick horizons. The morfological properties of soil profiles were studied and the samples were analysed on macroelements content and organic carbon. The total organic carbon contentrations were detected with spectrofotometric method and the concentrations of macroelements were analysed with X-ray fluorescence method. After wildfires on drained peatlands morfological and physico-chemical properties of soils were changed, the horizons of ash (up to 5 cm) and char (up to 3 cm) instead of organic layers were formed. In addition, the plots of post-pirogenic landscape were characterized by high variability of soil properties. For instance, the thickness of organic layer changed from 5 to 30 cm in a small plot of 5X5 m. The changes in element composition were detected. The peat horizons of background histosols had 80-90% of SiO2, 9-5,8% of Al2O3,1,5-5,6% of Fe2O3, 3,7-6,3% of CaO, 0,7-2,8 % of MnO. Background histic podsols contained 88-90% of SiO2, to 4,8% of Al2O3, and the proportion of Fe2O3 and MnO was about 2,3%. After the fire ash horizons had elevated concentrations of Al2O3 (9-17%), Fe2O3 (4-11%), P2O3 (1-1,8 %), CaO (1,9-2,8 %) and K2O (0,1-1,9%). The char horizons had composition similar to background peat. On the one hand the loss of organic matter took place after burning. But on the other hand after the fire new stage of humus formation started and in 2 years after the burning the content of organic carbon reached up to 10 % in upper horizons.

Aliphatic hydrocarbons recovered in vegetables from soils based on their in-situ distribution in various soil humus fractions using a successive extraction method.

PubMed

Zhang, Juan; Fan, Shu-Kai; Zhang, Ming-Hua; Grieneisen, Michael L; Zhang, Jian-Feng

2018-03-15

Aliphatic hydrocarbons (AHs) are major petroleum contaminants in the environment. In this study, the AHs bound to various soil endogenetic humus fractions were separated through successive extraction. Most of the AHs (46.1%) in soils were adsorbed onto/into humic acids (HA) and a small quantity of AHs (9.6%) were organic solvent extractable. AHs in B. chinensis were also analyzed since their potential risks to the residents through ingestion. AHs from C 21 to C 34 , so called high molecular weight AHs (HMWAHs), were dominant AHs in B. chinensis (85.5%) and soils (70.4%), followed by AHs from C 16 to C 21, whose mobility can be enhanced via binding to fulvic acids and then can be taken up by plant root lipids (soil-plant pathway). HMWAHs were mainly HA-bound and then were detained in the top soil layers. HMWAHs associated with fine topsoil particles could be transported to B. chinensis via the soil-air-plant pathway, including resuspension and aboveground plant cuticle capture. Results from Principal Component Analysis combined with Regression Analysis supported this assumption due to the positive correlations between HMWAHs concentration in B. chinensis and fine particle contents in soils. This work presents the distributions of petroleum contaminants that result from previously described behavior mechanisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Creation of Emergent Sandbar Habitat (ESH) in the Headwaters of Lewis and Clark Lake and the Impacts on Water Quality

DTIC Science & Technology

2009-04-01

probably tich in decayed vegetative matter (i.e., humus ) and seed stock. The richness of the matetial is indicated by its ctru·ker color as shown in...iron and manganese), humus and peat materials, plankton, weeds, and industrial wastes (APHA, 1998). “True color” is the color of water from which

Effects of Climate Changes and Pollution with Heavy Metals on the Transformation of Carbon Compounds in Different Soil Types of Agroecosystems in the Forest-Steppe of Baikal Region

NASA Astrophysics Data System (ADS)

Pomazkina, L. V.; Semenova, Yu. V.

2018-05-01

The results of long-term (1992-2005) monitoring of the carbon compounds transformation in soils of forest- steppe agroecosystems polluted by heavy metals in the Baikal region in the years different from the "climatic norm" are discussed. The influence of environmental factors on the functioning of microbial community was estimated by the Cmicr content and CO2 emission. The changes in the ecophysiological parameters (Cmicr/Corg and C-CO2/Cmicr, mg/(g h) related to the availability of the substrate and intensity of carbon (re)immobilization in different soils revealed the differences in the formation of a stable microbial community dependent on the environmental factors, especially in anomalous years. The use of a systemic approach and analysis of the carbon compounds transformation based on the proportion between the flows of net-mineralized and (re)immobilized carbon (NM: RI) allowed to evaluate integrally the functioning regime of the agroecosystems and the ecological impact on them. The differences in the functioning of agroecosystems on different heavy metal-polluted soils identified on the background of climatic changes are suitable for forecasting the current state and development of agroecosystems. For agroecosystems of this region, C-CO2 emission was estimated for the first time; it was more intense from the soils with the high humus content than from the soils poor in humus (141 and 101 g C/m2, respectively).

The methods of geomorphometry and digital soil mapping for assessing spatial variability in the properties of agrogray soils on a slope

NASA Astrophysics Data System (ADS)

Gopp, N. V.; Nechaeva, T. V.; Savenkov, O. A.; Smirnova, N. V.; Smirnov, V. V.

2017-01-01

The relationships between the morphometric parameters (MPs) of topography calculated on the basis of digital elevation model (ASTER GDEM, 30 m) and the properties of the plow layer of agrogray soils on a slope were analyzed. The contribution of MPs to the spatial variability of the soil moisture reached 42%; to the content of physical clay (<0.01 mm particles), 59%; to the humus content, 46%; to the total nitrogen content, 31%; to the content of nitrate nitrogen, 28%; to the content of mobile phosphorus, 40%; to the content of exchangeable potassium, 45%; to the content of exchangeable calcium, 67%; to the content of exchangeable magnesium, 40%; and to the soil pH, 42%. A comparative analysis of the plow layer within the eluvial and transitional parts of the slope was performed with the use of geomorphometric methods and digital soil mapping. The regression analysis showed statistically significant correlations between the properties of the plow layer and the MPs describing surface runoff, geometric forms of surface, and the soil temperature regime.

[Anaerobic reduction of humus/Fe (III) and electron transport mechanism of Fontibacter sp. SgZ-2].

PubMed

Ma, Chen; Yang, Gui-qin; Lu, Qin; Zhou, Shun-gui

2014-09-01

Humus and Fe(III) respiration are important extracellular respiration metabolism. Electron transport pathway is the key issue of extracellular respiration. To understand the electron transport properties and the environmental behavior of a novel Fe(III)- reducing bacterium, Fontibacter sp. SgZ-2, capacities of anaerobic humus/Fe(III) reduction and electron transport mechanisms with four electron acceptors were investigated in this study. The results of anaerobic batch experiments indicated that strain SgZ-2 had the ability to reduce humus analog [ 9,10-anthraquinone-2,6-disulfonic acid (AQDS) and 9,10-anthraquinone-2-sulfonic acid (AQS)], humic acids (HA), soluble Fe(III) (Fe-EDTA and Fe-citrate) and Fe(III) oxides [hydrous ferric oxide (HFO)]. Fermentative sugars (glucose and sucrose) were the most effective electron donors in the humus/Fe(III) reduction by strain SgZ-2. Additionally, differences of electron carrier participating in the process of electron transport with different electron acceptors (i. e. , oxygen, AQS, Fe-EDTA and HFO) were investigated using respiratory inhibitors. The results suggested that similar respiratory chain components were involved in the reducing process of oxygen and Fe-EDTA, including dehydrogenase, quinones and cytochromes b-c. In comparison, only dehydrogenase was found to participate in the reduction of AQS and HFO. In conclusion, different electron transport pathways may be employed by strain SgZ-2 between insoluble and soluble electron acceptors or among soluble electron acceptors. Preliminary models of electron transport pathway with four electron acceptors were proposed for strain SgZ-2, and the study of electron transport mechanism was explored to the genus Fontibacter. All the results from this study are expected to help understand the electron transport properties and the environmental behavior of the genus Fontibacter.

Impact of Urbanisation on Soil Organic Matter Content in chernozems in Vojvodina region

NASA Astrophysics Data System (ADS)

Samardžić, Miljan; Vasin, Jovica; Jajić, Igor; Vasenev, Ivan

2017-04-01

Vojvodina is the northern province of Serbia and the chief agricultural centre of the country. The main soil type in Vojvodina is chernozem (60% of total area), and it is under heavy anthropogenic pressure. Changes in soil organic matter amount resulting from switching from natural to urban ecosystems on Vojvodina's chernozem were not thoroughly researched in the past, which gave us unique insight in soil organic matter losses under human activity, namely urbanisation. The research has been carried out during July 2016 at Nature reserve Čarnok (as a control) and urban settlements Zmajevo, Vrbas and Kula, which are located 12 km from each other and Čarnok. Urban locations were lawns, chosen according to information from the owners (no known ploughing, no addition of sandy or clay material during last 70 years, no grass sowing and only direct human activity is trimming of grass). The results showed significant reduction of humus content in urban ecosystems: Čarnok (control, natural reserve) humus 5,33%, organic C 3,488%; Zmajevo humus 2,51%, organic C 1,963%; Vrbas humus 3,81%, organic C 4,216%; Kula humus 1,95%, organic C 1,517%. The differences in organic carbon also showed basically the same trend with notable exception of Vrbas. These differences in soil organic matter content is generally based on grass trimming practices. In Zmajevo, grass was trimmed monthly, with removal of biomass from the lawn, in Kula grass was trimmed twice per month with removal of biomass and in Vrbas trimming was performed once per week, with shredding of biomass and leaving it on the lawn. The conclusion was that land use change has advert impact on soil organic matter content in urban ecosystems, and that within it human practices such as trimming have significant impact on it.

Membrane-micelle model for humus in soils and sediments and its relation to humification

USGS Publications Warehouse

Wershaw, Robert L.

1994-01-01

Humification, the process whereby biomass consisting of dead plant and animal remains is converted into soil organic matter (humus), is one of the basic processes of the carbon cycle. The organic compounds that make up plant and animal tissue are thermodynamically unstable in the oxidizing atmosphere at the surface of the Earth. After the organisms in which they are incorporated die, the compounds are converted back to carbon dioxide and water by degradation reactions catalyzed by enzymes secreted by micro-organisms. However, not all the organic compounds in the dead biomass are immediately converted; some of the material is only partially oxidized. The residue left after partial oxidative degradation of the dead biomass is the source of the organic compounds that accumulate in soils and sediments as humus. Previously, humification was thought to involve a conversion of degradation products by a series of polymerization reactions into new types of polymeric species that are different from the precursor molecular species in the original biomass. However, it is proposed here that the depolymerization and oxidation reactions that take place during the enzymatic degradation of biopolymers produce amphiphiles--molecules that have a polar (hydrophilic) part and a nonpolar (hydrophobic) part. These amphiphiles that result from the partial oxidative degradation of dead biomass assemble spontaneously into ordered aggregates in which the hydrophobic parts of the molecules form the interiors and the hydrophilic parts of the molecules make up the exterior surfaces of the aggregates. These ordered aggregates constitute the humus in soils and sediments. Humus ordered aggregates most likely exist as bilayer membranes coating mineral grains and as micelles in solution.

Long-term dynamics of heavy metals in the upper horizons of soils in the region of a copper smelter impacts during the period of reduced emission

NASA Astrophysics Data System (ADS)

Vorobeichik, E. L.; Kaigorodova, S. Yu.

2017-08-01

The 23-year-long dynamics of actual acidity (pHwater) and acid-soluble heavy metals (Cu, Pb, Cd, Zn) in the forest litter and humus horizon of soils in spruce-fir forests were studied in the area subjected to the long-term (since 1940) pollution with atmospheric emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast). For this purpose, 25 permanent sample plots were established on lower slopes at different distances from the enterprise (30, 7, 4, 2, and 1 km; 5 plots at each distance) in 1989. The emissions from the smelter have decreased since the early 1990s. In 2012, the emissions of sulfur dioxide and dust decreased by 100 and 40 times, respectively, as compared with the emissions in 1980. Samples of litter and humus horizons were collected on permanent plots in 1989, 1999, and 2012. The results indicate that the pH of the litter and humus horizons restored to the background level 10 and 23 years after the beginning of the reduction in emissions, respectively. However, these characteristics in the impact zone still somewhat differ from those in the background area. In 2012, the content of Cu in the litter decreased compared to 1989 on all the plots; the content of Cu in the humus horizon decreased only in the close vicinity of the smelter. The contents of other metals in the litter and humus horizons remain constant or increased (probably because of the pH-dependent decrease in migration capacity). The absence of pronounced removal of metals from soils results in the retention of high contamination risk and the conservation of the suppressed state of biota within the impact zone.

Does simulated acid rain increase the leaching of cadmium from wood ash to toxic levels to coniferous forest humus microbes?

PubMed

Perkiömäki, Jonna; Fritze, Hannu

2003-05-01

Abstract Wood ash contains Cd in concentrations not permitted for fertilization use in agriculture (>3 mg kg(-1)). It has been shown that spiking ash with Cd to concentrations of 1000 mg kg(-1) induced no further changes in humus microbial activity and community structure as ash alone. To accelerate the weathering process and thus to liberate the spiked Cd from the ash, three treatments - wood ash (A), Cd spiked wood ash (ACd, 1000 mg Cd kg(-1) ash), both applied at a fertilization rate of 5000 kg ha(-1), together with a control (C) - were performed in microcosms and incubated in field condition under two types of irrigation - water and simulated acid rain. During the incubation period of one growing season the simulated acid rain plots received a sulfur load of 3.64 g S m(-2), which was 15 times more than the S deposition on the water irrigated plots. The treatments resulted in a mean Cd increase of the humus from 0.23 mg kg(-1) of the C treatment to 0.52 and 39.5 mg kg(-1) of the A and ACd treatments, respectively. The irrigation had no further effect on the result. The microbial activity, measured as soil basal respiration, and the microbial community structure, measured as humus phospholipid fatty acid and 16S and 18S polymerase chain reaction/denaturing gradient gel electrophoresis patterns, changed only due to the ash (A and ACd treatments) fertilization irrespective of the irrigation. The bacterial biosensor, emitting light in the presence of bioavailable Cd, did not react to any of the treatments. This result shows that Cd in ash was not leached into the humus due to increased deposition of acidified rain.

BOREAS HYD-6 Ground Gravimetric Soil Moisture Data

NASA Technical Reports Server (NTRS)

Carroll, Thomas; Knapp, David E. (Editor); Hall, Forrest G. (Editor); Peck, Eugene L.; Smith, David E. (Technical Monitor)

2000-01-01

The Boreal Ecosystem-Atmosphere Study (BOREAS) Hydrology (HYD)-6 team collected several data sets related to the moisture content of soil and overlying humus layers. This data set contains percent soil moisture ground measurements. These data were collected on the ground along the various flight lines flown in the Southern Study Area (SSA) and Northern Study Area (NSA) during 1994 by the gamma ray instrument. The data are available in tabular ASCII files. The HYD-06 ground gravimetric soil moisture data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Seasonal variation of cadmium toxicity toward the alga Selenastrum capricornutum Printz in two lakes with different humus content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laegreid, M.; Alstad, J.; Klaveness, D.

The alga Selenastrum capricornutum Printz is used to investigate the potential of natural lake water to reduce cadmium toxicity. The two lakes involved differ in trophic status and in concentration and composition of dissolved organic matter, one being a typical dystrophic bog lake, the other a less humus influenced, eutrophic lake. In the dystrophic lake, the toxic effect is determined mainly by the free cadmium activity. In the eutrophic, less humus influenced lake, however, the toxic effect shows considerable seasonal variations with a toxicity far exceeding what would be expected according to the estimated free ion activity during summer. Itmore » is hypothesized that qualitative changes in the composition of the dissolved organic matter during the production period are responsible for this effect.« less

The influences of four types of soil on the growth, physiological and biochemical characteristics of Lycoris aurea (L’ Her.) Herb

PubMed Central

Quan, Miaohua; Liang, Juan

2017-01-01

Based on the characteristics of Lycoris aurea (L. aurea) natural distribution and local soil types, we selected four representative types of soil, including humus soil, sandy soil, garden soil and yellow-brown soil, for conducting the cultivation experiments to investigate key soil factors influencing its growth and development and to select the soil types suitable for cultivating it. We found that there existed significant differences in the contents of mineral elements and the activities of soil enzymes (urease, phosphatase, sucrase and catalase) etc. Among which, the contents of organic matters, alkali-hydrolysable nitrogen, Ca and Mg as well as the activities of soil enzymes in humus soil were the highest ones. In yellow-brown soil, except for Fe, the values of all the other items were the lowest ones. Net photosynthetic rate (Pn), biomass and lycorine content in humus soil were all the highest ones, which were increased by 31.02, 69.39 and 55.79%, respectively, as compared to those of yellow-brown soil. Stepwise multiple regression analysis and path analysis indicated that alkali-hydrolysable nitrogen, and Ca etc. were key soil factors influencing Pn, biomass and lycorine content of L. aurea. Thus, humus soil can be used as medium suitable for artificial cultivation of L. aurea. PMID:28240308

The influences of four types of soil on the growth, physiological and biochemical characteristics of Lycoris aurea (L' Her.) Herb.

PubMed

Quan, Miaohua; Liang, Juan

2017-02-27

Based on the characteristics of Lycoris aurea (L. aurea) natural distribution and local soil types, we selected four representative types of soil, including humus soil, sandy soil, garden soil and yellow-brown soil, for conducting the cultivation experiments to investigate key soil factors influencing its growth and development and to select the soil types suitable for cultivating it. We found that there existed significant differences in the contents of mineral elements and the activities of soil enzymes (urease, phosphatase, sucrase and catalase) etc. Among which, the contents of organic matters, alkali-hydrolysable nitrogen, Ca and Mg as well as the activities of soil enzymes in humus soil were the highest ones. In yellow-brown soil, except for Fe, the values of all the other items were the lowest ones. Net photosynthetic rate (P n ), biomass and lycorine content in humus soil were all the highest ones, which were increased by 31.02, 69.39 and 55.79%, respectively, as compared to those of yellow-brown soil. Stepwise multiple regression analysis and path analysis indicated that alkali-hydrolysable nitrogen, and Ca etc. were key soil factors influencing P n , biomass and lycorine content of L. aurea. Thus, humus soil can be used as medium suitable for artificial cultivation of L. aurea.

Rheological Properties of Automorphic and Semihydromorphic Cryometamorphic Northern Taiga Soils in Northeastern European Russia (Komi Republic)

NASA Astrophysics Data System (ADS)

Kholopov, Yu. V.; Khaidapova, D. D.; Lapteva, E. M.

2018-04-01

Soil pastes at the water content corresponding to the maximum swelling of samples from different genetic horizons of cryometamorphic soils―surface-gleyic iron-illuvial svetlozem (Folic Albic Stagnosol) and peaty and peat humus-impregnated gleyic svetlozems (Histic Gleyic Stagnosols)―have been studied with an MCR-302 modular rheometer (Anton Paar, Austria). It has been found that the strongest interparticle bonds are formed in the horizons of cryometamorphic soils characterized by high contents of humic substances and organomineral Al-Fe-humus compounds. These are horizons of podzol microprofile (Eg and BHF) in iron-illuvial svetlozem and a humus-impregnated horizon (ELhi,g) in peaty and peat svetlozems. Organomineral Al-Fe-humus compounds, as well as the seasonal freezing of soils, determine the elastic-brittle character of interparticle interactions. The contents of clay fractions, exchangeable bases, and organic and organomineral substances impart viscoelastic properties to these contacts. An enhancement of elastic-brittle properties of soil is observed under the impact of gleying and freezing. The threefold decrease of the structural interaction parameter (∫ Z) when going from automorphic to semihydromorphic conditions indicates a decrease in the resistance of peaty and peat svetlozems to mechanical loads under increasing hydromorphism compared to iron-illuvial svetlozems.

Optimization of the Use of His₆-OPH-Based Enzymatic Biocatalysts for the Destruction of Chlorpyrifos in Soil.

PubMed

Senko, Olga; Maslova, Olga; Efremenko, Elena

2017-11-23

Applying enzymatic biocatalysts based on hexahistidine-containing organophosphorus hydrolase (His₆-OPH) is suggested for the decomposition of chlorpyrifos, which is actively used in agriculture in many countries. The application conditions were optimized and the following techniques was suggested to ensure the highest efficiency of the enzyme: first, the soil is alkalinized with hydrated calcitic lime Ca(OH)₂, then the enzyme is introduced into the soil at a concentration of 1000 U/kg soil. Non-equilibrium low temperature plasma (NELTP)-modified zeolite is used for immobilization of the relatively inexpensive polyelectrolyte complexes containing the enzyme His₆-OPH and a polyanionic polymer: poly-l-glutamic acid (PLE 50 ) or poly-l-aspartic acid (PLD 50 ). The soil's humidity is then increased up to 60-80%, the top layer (10-30 cm) of soil is thoroughly stirred, and then exposed for 48-72 h. The suggested approach ensures 100% destruction of the pesticide within 72 h in soils containing as much as 100 mg/kg of chlorpyrifos. It was concluded that using this type of His₆-OPH-based enzyme chemical can be the best approach for soils with relatively low humus concentrations, such as sandy and loam-sandy chestnut soils, as well as types of soil with increased alkalinity (pH 8.0-8.4). Such soils are often encountered in desert, desert-steppe, foothills, and subtropical regions where chlorpyrifos is actively used.

Optimization of the Use of His6-OPH-Based Enzymatic Biocatalysts for the Destruction of Chlorpyrifos in Soil

PubMed Central

Senko, Olga; Efremenko, Elena

2017-01-01

Applying enzymatic biocatalysts based on hexahistidine-containing organophosphorus hydrolase (His6-OPH) is suggested for the decomposition of chlorpyrifos, which is actively used in agriculture in many countries. The application conditions were optimized and the following techniques was suggested to ensure the highest efficiency of the enzyme: first, the soil is alkalinized with hydrated calcitic lime Ca(OH)2, then the enzyme is introduced into the soil at a concentration of 1000 U/kg soil. Non-equilibrium low temperature plasma (NELTP)-modified zeolite is used for immobilization of the relatively inexpensive polyelectrolyte complexes containing the enzyme His6-OPH and a polyanionic polymer: poly-l-glutamic acid (PLE50) or poly-l-aspartic acid (PLD50). The soil’s humidity is then increased up to 60–80%, the top layer (10–30 cm) of soil is thoroughly stirred, and then exposed for 48–72 h. The suggested approach ensures 100% destruction of the pesticide within 72 h in soils containing as much as 100 mg/kg of chlorpyrifos. It was concluded that using this type of His6-OPH-based enzyme chemical can be the best approach for soils with relatively low humus concentrations, such as sandy and loam-sandy chestnut soils, as well as types of soil with increased alkalinity (pH 8.0–8.4). Such soils are often encountered in desert, desert-steppe, foothills, and subtropical regions where chlorpyrifos is actively used. PMID:29168784

Humus status of soddy-podzolic soil upon application of different green manures

NASA Astrophysics Data System (ADS)

Tripol'Skaya, L. N.; Romanovskaya, D. K.; Shlepetiene, A.

2008-08-01

Results of studying the effect of different plant species on the humus status of loamy sandy soddy-podzolic soil were generalized. It was found that the application of different green manure species ( Lupinus luteus L., Trifolium pratense L., and Raphanus sativus L.) and straw from cereal crops ( Secale cereale, Hordeum L.) under percolative conditions helped to sustain a stable humus budget in grain agrophytocenoses. A significant change in the fractional composition of HAs and FAs occurred under the effect of green manure. The fractions of free HAs and those bound to clay minerals accumulated with the application of Trifolium pratense and Raphanus sativus biomass and cereal straw. Lower amounts of aggressive and free FAs were formed in the soil with the application of straw and fallow plants. The decomposition of green manure and the formation of humic substances also depended on the hydrothermal conditions during application of manure.

A method suitable for DNA extraction from humus-rich soil.

PubMed

Miao, Tianjin; Gao, Song; Jiang, Shengwei; Kan, Guoshi; Liu, Pengju; Wu, Xianming; An, Yingfeng; Yao, Shuo

2014-11-01

A rapid and convenient method for extracting DNA from soil is presented. Soil DNA is extracted by direct cell lysis in the presence of EDTA, SDS, phenol, chloroform and isoamyl alcohol (3-methyl-1-butanol) followed by precipitation with 2-propanol. The extracted DNA is purified by modified DNA purification kit and DNA gel extraction kit. With this method, DNA extracted from humus-rich dark brown forest soil was free from humic substances and, therefore, could be used for efficient PCR amplification and restriction digestion. In contrast, DNA sample extracted with the traditional CTAB-based method had lower yield and purity, and no DNA could be extracted from the same soil sample with a commonly-used commercial soil DNA isolation kit. In addition, this method is time-saving and convenient, providing an efficient choice especially for DNA extraction from humus-rich soils.

Dynamic modelling and humus balances as tools for estimating and upscaling soil carbon stock changes in temperate cropland

NASA Astrophysics Data System (ADS)

Oberholzer, Hans-Rudolf; Holenstein, Hildegard; Mayer, Jochen; Leifeld, Jens

2010-05-01

Humus balances are simple mathematical tools used by farmers for assessing the overall performance of their management in terms of soil organic matter changes. They are based on humus reproduction factors which themselves mainly depend on crop rotation, residue management, and amount and type of organic fertilization. Dynamic models, on the other hand, are typically complex and need more detailed input data and are designed to calculate the time course of soil carbon content. In both cases, thorough validation is needed to utilize their potential for estimating carbon stock changes. We compared the results of three humus balance methods SALCA-SQ (Neyroud 1997), VDLUFA method (VDLUFA 2004), Humod (Brock et al. 2008) and the RothC model with measured soil carbon stocks in a long-term experiment in Switzerland for the period 1977-2005 (Fliessbach et al 2007). The field trial comprises various minerally and organically fertilized treatments, the latter differing in the amount and composition of organics applied. All methods were able to distinguish systematic management effects on soil organic carbon (SOC). However, only those SOC trajectories calculated with the dynamic model RothC matched measured stocks quantitatively. For both, humus balances and dynamic modelling the result strongly depended on parameterization of organic fertilizers, i.e. its stability and organic matter content. Therefore, incomplete information on the amount and composition of organic fertilizer and lack of knowledge about its potential for humus reproduction is regarded an uncertainty in both dynamic modelling and humus balance calculation, and seems to be a major drawback for the reliable application of these approaches at the regional scale. Our results stress the need for more detailed and harmonized data bases of organic fertilizer composition and application rates. References Brock C., Hoyer U., Leithold G., Hülsbergen K.-J., 2008. Entwicklung einer praxisanwendbaren Methode der Humusbilanzierung im ökologischen Landbau. Abschlussbericht zum Projekt 03OE084, http://forschung.oekolandbau.de unter der BÖL-Bericht-ID 16447,184 pp. Fliessbach A, Oberholzer H.-R., Gunst L., Mäder P., 2007. Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming. Agriculture, Ecosystems and Environment 118, 273-284. Leifeld J., Reiser R., Oberholzer H.-R., 2009. Consequences of conventional vs. organic farming on soil carbon: Results from a 27-year field experiment. Agronomy Journal 101, 1204-1218. Neyroud J.-A., 1997. La part du sol dans la production intégrée 1. Gestion de la matière organique et bilan humique. Revue suisse d'agriculture, 29, 45-51. VDLUFA, 2004. VDLUFA-Standpunkt: Humusbilanzierung - Methode zur Beurteilung und Bemessung der Humusversorgung von Ackerland. Verband Deutscher Landwirtschaftlicher Untersuchungs- und Forschungsanstalten, Selbstverlag.

Depth distribution of (137)Cs in anthrosol from the experimental field "Radmilovac" near Belgrade, Serbia.

PubMed

Vukašinović, Ivana; Todorović, Dragana; Dorđević, Aleksandar; Rajković, Miloš B; Pavlović, Vladimir B

2013-09-01

This is a preliminary study of the depth distribution of (137)Cs radionuclides in cultivated anthrosol soil of a 15-year old peach tree plantation at the experimental field "Radmilovac" near Belgrade. Before planting, the soil was ploughed at the depth of 1 m. The soil had not been annually ploughed, irrigated and treated with mineral fertilizers for three years before sampling. Activity concentration for (137)Cs ranged from 1.8 Bq kg(-1) to 35 Bq kg(-1). Along the soil depth it varied highly, reaching as high a total variation coefficient as 83 %. Radiocaesium distribution patterns depended on the extent of soil mixing in the plough layer, as it was mechanically transferred from the surface to the lower soil layers during cultivation. (137)Cs was associated with humus content and fixation to clay fractions in the soil. Our results single out soil's hygroscopic water as a valuable parameter for (137)Cs behaviour that could be used commonly if the measurement is standardised.

Investigation of bacterial communities in peat land of the Gahai Lake natural conservation area

NASA Astrophysics Data System (ADS)

Bai, Yani; Wang, Jinchang; Zhan, Zhigao; Guan, Limei; Jin, Liang; Zheng, Guohua

2017-10-01

Peat is involved in the global carbon cycle and water conservation; therefore, it is implicated in global environmental change. Microorganisms play an important role in the function of peat. To investigate the bacterial communities in peat of Gahai Lake, different locations and depths were sampled and Illumina Miseq sequencing was used to analyze the microbial community. Chemical properties of peat samples were analyzed by China state standard methods (GB methods). The results showed that bacterial communities were affected by depth, with bacterial diversity and community structure at 90 and 120 cm significantly different from that at 10, 30 and 50 cm depth from the peat surface. Chemical properties of peat land including organic matter, total nitrogen and humus content did not significantly influence bacterial community structure in peat, with only one group from genus Rhizomicrobium that was significantly correlated with total nitrogen. A substantial proportion of the bacterial sequences were unclassified (1.4%), which indicates the great application potential of peat in the Gahai Lake natural conservation area in the future.

Stormwater infiltration and surface runoff pollution reduction performance of permeable pavement layers.

PubMed

Niu, Zhi-Guang; Lv, Zhi-Wei; Zhang, Ying; Cui, Zhen-Zhen

2016-02-01

In this paper, the laboratory-scale permeable pavement layers, including a surface permeable brick layer, coarse sand bedding layers (thicknesses = 2, 3.5, and 5 cm), and single-graded gravel sub-base layers (thicknesses = 15, 20, 25, and 30 cm), were built to evaluate stormwater infiltration and surface runoff pollution reduction performance. And, the infiltration rate (I) and concentrations of suspended solids (SS), total phosphorus (TP), chemical oxygen demand (COD), ammonia nitrogen, and total nitrogen (TN) were measured under the simulated rainfall intensity of 72.4 mm/h over duration of 60 min. The results indicate that the thickness factor primarily influences the infiltration rate and pollutant removal rate. The highest steady infiltration rate was for surface brick layer 51.0 mm/h, for 5-cm sand bedding layer 32.3 mm/h, and for 30-cm gravel sub-base layer 42.3 mm/h, respectively. The SS average removal rate was relative higher (79.8 ∼ 98.6 %) for all layers due to the interception and filtration. The average removal rates of TP and COD were for surface layer 71.2 and 24.1 %, for 5-cm bedding layer 54.8 and 9.0 %, and for 20-cm sub-base layer 72.2 and 26.1 %. Ammonia nitrogen and TN cannot steadily be removed by layers according to the experiment results. The optimal thickness of bedding sands was 5 cm, and that of sub-base gravels was 20 ∼ 30 cm.

Enhanced deodorization and sludge reduction in situ by a humus soil cooperated anaerobic/anoxic/oxic (A2O) wastewater treatment system.

PubMed

Yan, Xing; Li, Biqing; Lei, Fang; Feng, Xin; Pang, Bo

2016-08-01

Simultaneous sludge reduction and malodor abatement in humus soil cooperated an anaerobic/anoxic/oxic (A2O) wastewater treatment were investigated in this study. The HSR-A2O was composed of a humus soil reactor (HSR) and a conventional A2O (designated as C-A2O).The results showed that adding HSR did not deteriorate the chemical oxygen demand (COD) removal, while total phosphorus (TP) removal efficiency in HSR-A2O was improved by 18 % in comparison with that in the C-A2O. Both processes had good performance on total nitrogen (TN) removal, and there was no significant difference between them (76.8 and 77.1 %, respectively). However, NH4 (+)-N and NO3 (-)-N were reduced to 0.3 and 6.7 mg/L in HSR-A2O compared to 1.5 and 4.5 mg/L. Moreover, adding HSR induced the sludge reduction, and the sludge production rate was lower than that in the C-A2O. The observed sludge yield was estimated to be 0.32 kg MLSS/day in HSR-A2O, which represent a 33.5 % reduction compared to a C-A2O process. Activated sludge underwent humification and produced more humic acid in HSR-A2O, which is beneficial to sludge reduction. Odor abatement was achieved in HSR-A2O, ammonium (NH3), and sulfuretted hydrogen (H2S) emission decreased from 1.34 and 1.33 to 0.06 mg/m(3), 0.025 mg/m(3) in anaerobic area, with the corresponding reduction efficiency of 95.5 and 98.1 %. Microbial community analysis revealed that the relevant microorganism enrichment explained the reduction effect of humus soil on NH3 and H2S emission. The whole study demonstrated that humus soil enhanced odor abatement and sludge reduction in situ.

The effect of changing land use on soil radiocarbon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harrison, K.G.; Broecker, W.S.; Bonani, G.

Most carbon budgets require greening of the terrestrial biosphere as a sink for some of the excess carbon dioxide produced by fossil fuel burning and deforestation. Much of this storage is thought to occur in soils, but running counter to this conclusion is the observation that cultivation has reduced the agricultural reservoir of soil humus. Radiocarbon measurements in agricultural soils lend support to this browning of agricultural lands. Moreover, the loss is from the fast cycling portion of the humus.

Soils of mountainous forest-steppe in the southwestern part of Khentei Ridge (Mongolia)

NASA Astrophysics Data System (ADS)

Ubugunova, V. I.; Baldanov, B. Ts.; Gunin, P. D.; Bazha, S. N.

2017-09-01

The study of soil cover in the mountainous forest-steppe on the southwestern macroslope of Khentei Ridge has shown that the spatial distribution of soils is controlled by the ruggedness of topography, slope aspects, geocryological conditions, and the thickness of loose deposits. The soils belong to the orders of lithozems and organo-accumulative soils (Mollic Leptosols) of the postlithogenic trunk of pedogenesis. Dark-humus and mucky-dark-humus horizons of the organic matter accumulation are characteristic features of these soils. The investigated area is differentiated according to the soil moistening conditions on the slopes of different aspects. Favorable growth conditions for dwarf birch and Siberian larch at the southern boundary of the boreal forests in Mongolia are explained by the relatively high moistening of mucky-darkhumus lithozems and mucky-dark-humus soils developed on windward northern slopes and on mountain terraces in places of the local snow accumulation by wind. An important role in preservation of forest vegetation belongs to permafrost in small cirque-like depressions.

Batch study of manganese removal from mine effluent using mixture of ferromanganese ore and humus

NASA Astrophysics Data System (ADS)

Kamal, Norinsafrina Mustaffa; Aziz, Hamidi Abdul; Sulaiman, Shamsul Kamal; Hussin, Hashim

2017-10-01

Environmental problem related to mining industry always associates with high heavy metal contents in mine effluent. Manganese is among the metals that need to be reduced before the mine effluent entering receiving waterways. In this batch study, mixture of ferromanganese ore and humus had been applied to remove manganese from mine effluent. Effect of particle size of ferromanganese ore, dosage, mix ratio, pH and contact time had been studied to examine the effectiveness of the mixture in removing manganese. Results from the study have shown that optimum manganese removal was 93.54% by using particle size of 0.25-0.5 mm of ferromanganese ore, 3g of dosage mixture, mix ratio of 20%;80%, solution pH of 7 and 210 minutes (3.5 hours) of contact time. Thus, it is proven that mixture of ferromanganese ore and humus has potential to be used for removal of manganese in mine effluent.

Influence of windthrows and tree species on forest soil plant biomass and carbon stocks

NASA Astrophysics Data System (ADS)

Veselinovic, B.; Hager, H.

2012-04-01

The role of forests has generally been recognized in climate change mitigation and adaptation strategies and policies (e.g. Kyoto Protocol within articles 3.3 and 3.4, RES-E Directive of EU, Country Biomass Action Plans etc.). Application of mitigation actions, to decrease of CO2-emissions and, as the increase of carbon(C)-stocks and appropriate GHG-accounting has been hampered due to a lack of reliable data and good statistical models for the factors influencing C-sequestration in and its release from these systems (e.g. natural and human induced disturbances). Highest uncertainties are still present for estimation of soil C-stocks, which is at the same time the second biggest C-reservoir on earth. Spruce monocultures have been a widely used management practice in central Europe during the past century. Such stands are in lower altitudes (e.g. submontane to lower montane elevation zone) and on heavy soils unstable and prone to disturbances, especially on blowdown. As the windthrow-areas act as CO2-source, we hypothesize that conversion to natural beech and oak forests will provide sustainable wood supply and higher stability of stands against blowdown, which simultaneously provides the long-term belowground C-sequestration. This work focuses on influence of Norway spruce, Common beech and Oak stands on belowground C-dynamics (mineral soil, humus and belowground biomass) taking into consideration the increased impact of windthrows on spruce monocultures as a result of climate change. For this purpose the 300-700m altitude and pseudogley (planosols/temporally logged) soils were chosen in order to evaluate long-term impacts of the observed tree species on belowground C-dynamics and human induced disturbances on secondary spruce stands. Using the false chronosequence approach, the C-pools have been estimated for different compartments and age classes. The sampling of forest floor and surface vegetation was done using 30x30 (homogenous plots) and 50x50cm (inhomogeneous plots) frame. It was distinguished between following fractions: fine/coarse roots ( than 2mm), woody debris (dead wood, branches and seeds), living vegetation (ground vegetation and its roots), litter (leaves fresh and decomposed until the stage where the basic form can still be recognized) and humus layer (more than 30% organic matter in the fine fraction). Mineral soil was sampled down to 1m depth. The C stocks for 60 and 100cm depth were evaluated. The data enable a good overview of allocation of organic C within the belowground compartments, and its dynamics over the stand development stages for the relevant tree species of the Northern Alpine Foothills. In addition, these data enable the simulation of the long-term development of the belowground biomass and C-stocks for the three different stand types (pure spruce stands, mixed beech-spruce stands and oak stands). These results enable improvement of the statistical models in relation to site factors or stocking tree species and serve herewith further, as a valuable decision support for the innovative forest management practices and ensure the accomplishment of ecological, social and economical services of forest ecosystems.

Changes in quantity and spectroscopic properties of water-extractable organic matter during soil aquifer treatment.

PubMed

Xue, S; Zhao, Q L; Wei, L L; Ma, X P; Tie, M

2013-01-01

The aim of this study was to identify qualitative and quantitative changes in the character of water-extractable organic matter (WEOM) in soils as a consequence of soil aquifer treatment (SAT). Soil samples were obtained from a soil-column system with a 2-year operation, and divided into seven layers from top to bottom: CS1 (0-12.5 cm), CS2 (12.5-25 cm), CS3 (25-50 cm), CS4 (50-75 cm), CS5 (75-100 cm), CS6 (100-125 cm) and CS7 (125-150 cm). A sample of the original soil used to pack the columns was also analysed to determine the effects of SAT. Following 2 years of SAT operation, both soil organic carbon and water-extractable organic carbon were shown to accumulate in the top soil layer (0-12.5 cm), and to decrease in soil layers deeper than 12.5 cm. The WEOM in the top soil layer was characterized by low aromaticity index (AI), low emission humification index (HIX) and low fluorescence efficiency index (F(eff)). On the other hand, the WEOM in soil layers deeper than 12.5 cm had increased values of HIX and F(eff), as well as decreased AI values relative to the original soil before SAT. In all soil layers, the percentage of hydrophobic and transphilic fractions decreased, while that of the hydrophilic fraction increased, as a result of SAT. The production of the amide-2 functional groups was observed in the top soil layer. SAT operation also led to the enrichment of hydrocarbon and amide-1 functional groups, as well as the depletion of oxygen-containing functional groups in soil layers deeper than 12.5 cm.

Mineralization of organic-matter labile fragments in the humus-accumulative horizon of soddy-podzolic soil

NASA Astrophysics Data System (ADS)

Trofimov, S. Ya.; Lazarev, A. S.; Fokin, A. D.

2012-12-01

The mineralization rate of the 14C-labeled organic matter (OM) in the humus-accumulative AE horizon of a soddy-podzolic soil was determined in a laboratory experiment. The labeling was performed in a field experiment when microamounts of 14C-labeled glucose, glycine, and uracil were added to tree waste in sacks embedded in the upper layer of the forest litter. Samples containing 14C were taken from the AE horizon (above which the sacks with the labeled material were placed) 7 and 20 months after the beginning of the experiment. The soil samples were wetted to a water content corresponding to ˜80% of the total water capacity and placed in hermetic vessels containing vials with a periodically renewed alkali solution. The incubation was performed at room temperature for 3.5 months; the alkali solutions in the vials were replaced and titrated 12 times during this period. Mineralization curves were plotted from the amounts of carbon dioxide absorbed by a 0.3 N NaOH solution, which were calculated for each time interval; its 14C content was determined by the scintillation method. The experimental treatments also included the determination of the OM mineralization rate in material from the AE horizon pretreated with a heavy liquid or a heavy liquid and a 0.1 N NaOH solution. The differences between the mineralization rates of the labeled organic matter applied to the soil in the form of glucose, glycine, and uracil under the field conditions after the interaction for 7 and 20 months were revealed. The changes in the mineralization rate after the successive extraction of the labile organic matter with a heavy liquid and a 0.1 N NaOH solution were studied. It was shown that the transformation of the labeled low-molecular-weight organic compounds in the soil over 20 months included their strong inclusion into the humus composition, which was confirmed by the similar values of the mineralization constants of the native and 14C-labeled OM. In addition, the treatments with the heavy liquid or the heavy liquid and the NaOH solution had almost identical effects on the mineralization of the native and 14C-labeled OM. The mineralization constants of the native and 14C-labeled OM in the samples taken after 7 months of the field experiment differed significantly.

Cover-crops - improvement of soil fertility and provision of biomass

NASA Astrophysics Data System (ADS)

Kirchmeyr, Franz; Szerencsits, Manfred

2017-04-01

Besides climate change, erosion, inadequate crop rotation and intensive tillage may turn arable land into marginal land. On the other hand, reclamation approaches which include arable farming methods may result only in short-term success if they do not consider their effects on humus content and erosion. Additionally, effective reclamation will also have to address the growing need for food production besides biomass provision. Therefore, we investigated if cover or catch crops (CC) may accomplish both goals: Improve soil quality and humus content even if CC-biomass is used for biogas production. Humus content and soil fertility: In comparison to complete fallow in a crop rotation with silage maize and cereals the humus balance can be improved from -50 to +280 kg humus carbon (C) ha-1 year-1 through additional CC (4.5 t DM ha-1) used for biogas production and an equivalent amount of digestate returned to the field. With a CC-yield of 2.5 t DM ha-1 the humus balance results in 220 kg C ha-1 year-1. It is still slightly higher if the same CC remains on the field as green manure (170 kg C ha-1 year-1). Additionally it is important to consider that 20 - 50 % of the assimilated carbon can be found in the plant roots and that roots and root exudates as well as CC harvest residues provide fresh organic matter for soil life. Furthermore, biomass production of cover crops was considerably higher, if they were used for biogas production because of earlier cultivation and later harvest than mulching. Erosion control: The risk of erosion can be reduced by approx. 50 % in comparison to complete fallow if CC with 2.5 t DM ha-1 remain on the field as green manure. A comparable reduction can be achieved, if CC with 4.5 t DM ha-1 are harvested for biogas production. Because of better weed suppression, tilth and soil structure of CC with higher biomass, it is more likely to apply conservation tillage and avoid ploughing. Without ploughing a CC with 4.5 t DM ha-1 used for biogas the risk of erosion can even be reduced by approx. 75 % in comparison to complete fallow with ploughing. Water balance and quality: On the plots of our field experiments approx. 30 % of the precipitation contributed to groundwater recharge in crop rotations without CC. With 2.5 t CC DM ha-1 remaining on the field as green manure groundwater recharge was reduced to approx. 27 % whereas 4.5 t DM CC ha-1 caused a reduction to approx. 25 %. On the long term it can be expected that reduced erosion and increased humus content may improve the water storage capacity of soils and in this way reduce surface runoff and the risk of flooding. Additionally we found that CC remaining as green manure reduced the total nitrate leaching by 6 %. CC used for biogas reduced total leaching in comparison to complete fallow by 26 %.

The effect of woven roving fiberglass total layers on resin infusion time in vacuum infusion

NASA Astrophysics Data System (ADS)

Saputra, A. H.; Ibrahim, R. H.

2018-04-01

Composite material consists of reinforcement materials and resin as a matrix. Vacuum infusion isone of composite material manufacturing process. This process is to minimize the air cavity on composite material. The composite material will have good mechanical properties. There is a problem in vacuum infusion related to resin gelling time that must be considered. In this study, the area as well as the reinforcement layers are variated. Unsaturated polyester was used as resin and woven roving fiberglass was used as reinforcement. This study was obtained that resin infusion time data for woven roving, 15x20 cm of size, in two until six layers are 55 seconds to 78 seconds; whereas, the infusion times for 15x25 cm of size,in two until six layers are 119 seconds to 235 seconds; whereas the infusion time for 15x35 cm of size, in two until six layers are 181 seconds to 303 seconds. By data processing, the maximum fiber area that resin still can flow, for 6 layers, is 0,4391 m2 (or 15 cm x 2.92m). Maximum fiber total layers for the specimen with 15x20cm2, 15x25cm2 and 15x35 cm2 of areaare 147, 145 and 125 layers respectively.

Rapid prediction of particulate, humus and resistant fractions of soil organic carbon in reforested lands using infrared spectroscopy.

PubMed

Madhavan, Dinesh B; Baldock, Jeff A; Read, Zoe J; Murphy, Simon C; Cunningham, Shaun C; Perring, Michael P; Herrmann, Tim; Lewis, Tom; Cavagnaro, Timothy R; England, Jacqueline R; Paul, Keryn I; Weston, Christopher J; Baker, Thomas G

2017-05-15

Reforestation of agricultural lands with mixed-species environmental plantings can effectively sequester C. While accurate and efficient methods for predicting soil organic C content and composition have recently been developed for soils under agricultural land uses, such methods under forested land uses are currently lacking. This study aimed to develop a method using infrared spectroscopy for accurately predicting total organic C (TOC) and its fractions (particulate, POC; humus, HOC; and resistant, ROC organic C) in soils under environmental plantings. Soils were collected from 117 paired agricultural-reforestation sites across Australia. TOC fractions were determined in a subset of 38 reforested soils using physical fractionation by automated wet-sieving and 13 C nuclear magnetic resonance (NMR) spectroscopy. Mid- and near-infrared spectra (MNIRS, 6000-450 cm -1 ) were acquired from finely-ground soils from environmental plantings and agricultural land. Satisfactory prediction models based on MNIRS and partial least squares regression (PLSR) were developed for TOC and its fractions. Leave-one-out cross-validations of MNIRS-PLSR models indicated accurate predictions (R 2  > 0.90, negligible bias, ratio of performance to deviation > 3) and fraction-specific functional group contributions to beta coefficients in the models. TOC and its fractions were predicted using the cross-validated models and soil spectra for 3109 reforested and agricultural soils. The reliability of predictions determined using k-nearest neighbour score distance indicated that >80% of predictions were within the satisfactory inlier limit. The study demonstrated the utility of infrared spectroscopy (MNIRS-PLSR) to rapidly and economically determine TOC and its fractions and thereby accurately describe the effects of land use change such as reforestation on agricultural soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Light Gray Surface-Gleyed Loamy Sandy Soils of the Northern Part of Tambov Plain: Agroecology, Properties, and Diagnostics

NASA Astrophysics Data System (ADS)

Zaidel'man, F. R.; Stepantsova, L. V.; Nikiforova, A. S.; Krasin, V. N.; Dautokov, I. M.; Krasina, T. V.

2018-04-01

Light gray soils of Tambov oblast mainly develop from sandy and loamy sandy parent materials; these are the least studied soils in this region. Despite their coarse texture, these soils are subjected to surface waterlogging. They are stronger affected by the agrogenic degradation in comparison with chernozems and dark gray soils. Morphology, major elements of water regime, physical properties, and productivity of loamy sandy light gray soils with different degrees of gleyzation have been studied in the northern part of Tambov Plain in order to substantiate the appropriate methods of their management. The texture of these soils changes at the depth of 70-100 cm. The upper part is enriched in silt particles (16-30%); in the lower part, the sand content reaches 80-85%. In the nongleyed variants, middle-profile horizons contain thin iron-cemented lamellae (pseudofibers); in surface-gleyed variants, iron nodules are present in the humus horizon. The removal of clay from the humus horizon and its accumulation at the lithological contact and in pseudofibers promote surface subsidence and formation of microlows in the years with moderate and intense winter precipitation. The low range of active moisture favors desiccation of the upper horizons to the wilting point in dry years. The yield of cereal crops reaches 3.5-4.5 t/ha in the years with high and moderate summer precipitation on nongleyed and slightly gleyed light gray soils and decreases by 20-50% on strongly gleyed light gray soils. On light gray soils without irrigation, crop yields are unstable, and productivity of pastures is low. High yields of cereals and vegetables can be obtained on irrigated soils. In this case, local drainage measures should be applied to microlows; liming can be recommended to improve soil productivity.

Effect of raw humus under two adult Scots pine stands on ectomycorrhization, nutritional status, nitrogen uptake, phosphorus uptake and growth of Pinus sylvestris seedlings.

PubMed

Schulz, Horst; Schäfer, Tina; Storbeck, Veronika; Härtling, Sigrid; Rudloff, Renate; Köck, Margret; Buscot, François

2012-01-01

Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth.

HydroCrowd: a citizen science snapshot to assess the spatial control of nitrogen solutes in surface waters

PubMed Central

Breuer, Lutz; Hiery, Noreen; Kraft, Philipp; Bach, Martin; Aubert, Alice H.; Frede, Hans-Georg

2015-01-01

We organized a crowdsourcing experiment in the form of a snapshot sampling campaign to assess the spatial distribution of nitrogen solutes, namely, nitrate, ammonium and dissolved organic nitrogen (DON), in German surface waters. In particular, we investigated (i) whether crowdsourcing is a reasonable sampling method in hydrology and (ii) what the effects of population density, soil humus content and arable land were on actual nitrogen solute concentrations and surface water quality. The statistical analyses revealed a significant correlation between nitrate and arable land (0.46), as well as soil humus content (0.37) but a weak correlation with population density (0.12). DON correlations were weak but significant with humus content (0.14) and arable land (0.13). The mean contribution of DON to total dissolved nitrogen was 22%. Samples were classified as water quality class II or above, following the European Water Framework Directive for nitrate and ammonium (53% and 82%, respectively). Crowdsourcing turned out to be a useful method to assess the spatial distribution of stream solutes, as considerable amounts of samples were collected with comparatively little effort. PMID:26561200

Effects of human placental S9 and induced rat liver S9 on the mutagenicity of drinking waters processed from humus-rich surface waters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vartiainen, T.; Lampelo, S.

The mutagenicity of chlorinated drinking waters processed from humus-rich surface waters has been shown to be very high. The effect of placental S9 on the mutagenicity of drinking waters has not been studied previously. The purpose of this study was to compare the effects of human placental and rat liver microsomal fractions on the mutagenicity of drinking waters processed from humus-rich surface waters. The samples of 34 drinking and two raw waters from 26 localities in Finland were tested for mutagenicity in Ames Salmonella typhimurium tester strain TA100 with and without metabolic activations. Between the drinking water samples, clear differencesmore » were recorded in the presence of placental and rat liver S9, suggesting different mutagens in the drinking waters. Rat liver S9 decreased the mutagenicities of drinking water concentrates, but placental S9 increased, decreased, or had no effect. It is not known if placental mutagenicity enhancing system might cause any health hazard to a developing fetus.« less

Solar sanitary system (SOL-SAN)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, J.C.

Ordinary composting toilets, because of cooling by evaporation, do not heat the product (humus) hot enough to kill all pathogenic viruses, bacteria, or parasite eggs and cysts. The SOL-SAN system uses direct radiation to pasteurize incoming river water for drinking and also, separately, to pasteurize and dry the humus, and to pasteurize the effluent gray/brown water. Work is in progress on simple fool-proof methods of insuring that the water will not flow out unless it has been pasteurized. Heat exchangers recapture the heat from these very hot pasteurized liquids, thereby warming more in-coming water for washing, which is important formore » preventing transmission of pathogenic microbes. When pasteurized, the humus and gray/brown water can safely be recycled to fertilize and water the family vegetable garden. Thus no sewer would be needed, and the vegetables or fish would grow well. Widespread use of the SOL-SAN system would save water and nutrients, reduce the prevalence of infectious diseases, improve the nutrition and vitality of the population, and save the large fraction of human food now consumed by parasites.« less

The organic matter of the different ages fallow Luvisols

NASA Astrophysics Data System (ADS)

Giniyatullin, K. G.; Valeeva, A. A.; Smirnova, E. V.; Okunev, R. V.; Latipova, L. I.

2018-01-01

The study of the change in the humus state of the fallow Luvisols of different ages under the influence of weeds and meadow vegetation was carried out in dynamics (after 5 years). It is shown that both under weedy and meadow vegetation there is a statistically significant accumulation of organic matter in the upper part of the long-arable horizon. Based on the study of composition and spectral properties of soil organic matter in fallow soils of different ages concluded that the significant qualitative change of the humus state of fallow soils requires significant time, measured at least decades.

Utilization of humus-rich forest soil (mull) in geochemical exploration for gold

USGS Publications Warehouse

Curtin, Gary C.; Lakin, H.W.; Neuerburg, G.J.; Hubert, A.E.

1968-01-01

Distribution of gold in humus-rich forest soil (mull) reflects the known distribution of gold deposits in bedrock in the Empire district, Colorado. Gold from the bedrock is accumulated by pine and aspen trees and is concentrated in the mull by the decay of organic litter from the trees. Anomalies in mull which do not coincide with known gold deposits merit further exploration. The gold anomalies in soil (6- to 12-inch depth) and in float pebbles and cobbles poorly reflect the known distribution of gold deposits in bedrock beneath the extensive cover of colluvium and glacial drift.

Features of distribution and quality of organic matter in the bottom sediments of the Great Peter Bay (Sea of Japan)

NASA Astrophysics Data System (ADS)

Nesterova, Olga; Tregubova, Valentina; Semal, Victoria; Vasenev, Ivan

2017-04-01

The nature and distribution of organic carbon in marine waters depends on: 1) biological productivity and revenue of the autochthonous organic matter to the bottom; 2) sediment grain-size composition and conditions of dumping, which in turn depends of hydrothermic regime, topography, speed River mist and received major erosion products; 3) living conditions of the benthos (the quantity consumed of OM, gas regime of habitats, physiological capacity of heterotrophs). Autochthonous OM of phytoplankton plays a dominant role in the processes of formation of humus in aquatic conditions. Bottom sediments at different distance from the shoreline to depths from 0.5 up to 480 m of the Sea of Japan, which are formed in various conditions of facies, were selected as the objects of study. There is no clear relationships to the amount of organic matter in bottom sediments on the characteristics of the distribution and nature of living matter in the oceans and seas. This is because the process of sedimentation and fossilization of organic matter on the seabed and the ocean floor depends on many factors (currents, depth). Humus of studied bottom sediments in composition can be attributed mainly to the humic type. Nonhydrolyzing rest is 70-90%. This is characteristic of bottom sediments formed in facial types of small bays, internal coastal shelf bights and the underwater slope. At a fraction of the carbon of humic acids in organic matter, ranging from 4 to 80% of the amount of humic and fulvic acids. Fulvic acids content is much less. This is due to more favourable conservation situation of humic acids in precipitation with high content of organic matter, whereas fulvic acids in aquatic environments are more labile and almost not dumped. Despite the fact humic acids are not the most stable component (s), however, with increased content of humic acids, the mobility of organic matter and removing it from the bottom sediments are reduced. Internal shelf facies of the Great Peter Bay is the most diverse on the content of the various components of the bottom sediments humus. This is because modern processes of sedimentations and humus formation are active in this zone. The greatest concentration of organic matter in conjunction with the submarine and coastal slope at depths of more than 120 m. Slight variations parameters that characterize the composition of humus, are notable for all bottom sediments, as well as the marine environment, largely cancels the General conditions of humus formation around the basin of the Sea of Japan. Organic substance moving in the water colomn and transforms. Only sustainable to mineralization of organic substance reaches the bottom.

Modelling and mapping the topsoil organic carbon content for Tanzania

NASA Astrophysics Data System (ADS)

Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

2014-05-01

Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small-scale Soil and Terrain (SOTER) map. Prediction uncertainty was quantified by the 90% prediction interval and the predictions were validated by cross-validation. The SOTER map proved to be the best predictor of SOC content, followed by the terrain parameters, mid-infrared reflectance, surface temperature, several vegetation indices, and the land cover map. The maps show that the SOC content decreases with depth, which is typically observed in soils. For the 0-10 cm layer the average predicted SOC content is 1.31%, for the 10-20 cm layer this is 0.93%, for the 20-30cm layer 0.72%, and for the 0-30cm layer 1.00%. The mean absolute error of the 0-10cm layer was 0.54%, that of the 10-20cm layer 0.38%, that of the 20-30cm layer 0.31%, and that of the 0-30cm layer 0.34%. The R2-value of the 0-10 cm layer was 0.47, that of the 10-20cm layer 0.49, that of the 20-30cm layer 0.44, and that of the 0-30cm layer 0.59. The next step will be the development of maps of SOC stock and key properties that are of interest for soil fertility management such as pH and the textural fractions.

[Effects of water storage in deeper soil layers on the root growth, root distribution and economic yield of cotton in arid area with drip irrigation under mulch].

PubMed

Luo, Hong-Hai; Zhang, Hong-Zhi; Zhang, Ya-Li; Zhang, Wang-Feng

2012-02-01

Taking cotton cultivar Xinluzao 13 as test material, a soil column culture expenment was conducted to study the effects of water storage in deeper (> 60 cm) soil layer on the root growth and its relations with the aboveground growth of the cultivar in arid area with drip irrigation under mulch. Two levels of water storage in 60-120 cm soil layer were installed, i. e., well-watered and no watering, and for each, the moisture content in 0-40 cm soil layer during growth period was controlled at two levels, i.e., 70% and 55% of field capacity. It was observed that the total root mass density of the cultivar and its root length density and root activity in 40-120 cm soil layer had significant positive correlations with the aboveground dry mass. When the moisture content in 0-40 cm soil layer during growth season was controlled at 70% of field capacity, the total root mass density under well-watered and no watering had less difference, but the root length density and root activity in 40-120 cm soil layer under well-watered condition increased, which enhanced the water consumption in deeper soil layer, increased the aboveground dry mass, and finally, led to an increased economic yield and higher water use efficiency. When the moisture content in 0-40 cm soil layer during growth season was controlled at 55% of field capacity and the deeper soil layer was well-watered, the root/shoot ratio and root length density in 40-120 cm soil layer and the root activity in 80-120 cm soil layer were higher, the water consumption in deeper soil layer increased, but it was still failed to adequately compensate for the negative effects of water deficit during growth season on the impaired growth of roots and aboveground parts, leading to a significant decrease in the economic yield, as compared with that at 70% of field capacity. Overall, sufficient water storage in deeper soil layer and a sustained soil moisture level of 65% -75% of field capacity during growth period could promote the downward growth of cotton roots, which was essential for achieving water-saving and high-yielding cultivation of cotton with drip irrigation under mulch.

The balance model of oxygen enrichment of atmospheric air

NASA Astrophysics Data System (ADS)

Popov, Alexander

2013-04-01

The study of turnover of carbon and oxygen is an important line of scientific investigation. This line takes on special significance in conditions of soil degradation, which leads to the excess content of carbon dioxide and, as result, decrease of oxygen in the atmosphere. The aim of this article is a statement the balance model of oxygen enrichment of atmospheric air (ratio O/C) depending on consumption and assimilation by plants of dissolved organic matter (DOM) and the value of the oxidation-reduction potential (Eh). Basis of model was the following: green vascular plants are facultative heterotrophic organisms with symbiotic digestion and nutrition. According to the trophology viewpoint, the plant consumption of organic compounds broadens greatly a notion about the plant nutrition and ways of its regulation. In particular, beside the main known cycle of carbon: plant - litter - humus - carbon dioxide - plant, there is the second carbon cycle (turnover of organic compounds): plant - litter - humus - DOM - plant. The biogeochemical meaning of consumption of organic compounds by plants is that plants build the structural and functional blocks of biological macromolecules in their bodies. It provides receiving of a certain "energy payoff" by plants, which leads to increase of plant biomass by both an inclusion of allochthonous organic molecules in plant tissues, and positive effect of organic compounds on plant metabolic processes. One more of powerful ecological consequence of a heterotrophic nutrition of green plants is oxygen enrichment of atmospheric air. As the organic molecules in the second biological cycle of carbon are built in plants without considerable chemical change, the atmospheric air is enriched on that amount of oxygen, which would be required on oxidation of the organic molecules absorbed by plants, in result. It was accepted that: plant-soil system was climax, the plant community was grassy, initial contents of carbon in phytomass was accepted as 1, annually from 60 to 100 % of the plant litter could arrive to the soil; coefficients of humification of both plant litter and DOM were 0.1 (10 %); DOM is formed as a result of hydrolytic destruction of plant litter, newly formed humic substances (HS) and humus; coefficient of possible absorption of DOM by plants - 0.1 (10 %); it was considered that all organic compounds affiliated into DOM had positive physiological effect on green plants; it was accepted that 1 % DOM absorbed by plants increases phytomass on 10 % (for example, at the expense of photosynthesis acceleration); Eh value was changed from 300 to 800 mV; depending on Eh (i) the coefficient of plant litter oxidation was in the range from 0.75 (75 %) to 0.8 (90 %), coefficient of oxidation of DOM and newly formed HS - from 0.85 (85 %) to 0.9 (90 %), and coefficient of humus oxidation from 0 (0 %) to 0.05 (5 %), and (ii) coefficient of hydrolytic destruction of plant litter and newly formed HS was in the range from 0.12 (12 %) to 0.07 (7 %), and coefficient of humus hydrolytic destruction from 0,05 (5 %) to 0 (0 %), accordingly; all dependences were quasilinear. The following conclusions have been made based on the modeling: (i) both phytomass and oxygen content in atmospheric air were increased with increase of DOM part absorbed by green vascular plants; (ii) the abundance of humus was increased with increase of DOM consumption by green plant (on 5 % at all Eh values) too; (iii) the increase of Eh with 300 to 800 mV led to reduction of oxygen in atmospheric air and to quadruple decrease of the abundance of humus.

[Soil organic carbon mineralization of Black Locust forest in the deep soil layer of the hilly region of the Loess Plateau, China].

PubMed

Ma, Xin-Xin; Xu, Ming-Xiang; Yang, Kai

2012-11-01

The deep soil layer (below 100 cm) stores considerable soil organic carbon (SOC). We can reveal its stability and provide the basis for certification of the deep soil carbon sinks by studying the SOC mineralization in the deep soil layer. With the shallow soil layer (0-100 cm) as control, the SOC mineralization under the condition (temperature 15 degrees C, the soil water content 8%) of Black Locust forest in the deep soil layer (100-400 cm) of the hilly region of the Loess Plateau was studied. The results showed that: (1) There was a downward trend in the total SOC mineralization with the increase of soil depth. The total SOC mineralization in the sub-deep soil (100-200 cm) and deep soil (200-400 cm) were equivalent to approximately 88.1% and 67.8% of that in the shallow layer (0-100 cm). (2) Throughout the carbon mineralization process, the same as the shallow soil, the sub-deep and deep soil can be divided into 3 stages. In the rapid decomposition phase, the ratio of the mineralization or organic carbon to the total mineralization in the sub-deep and deep layer (0-10 d) was approximately 50% of that in the shallow layer (0-17 d). In the slow decomposition phase, the ratio of organic carbon mineralization to total mineralization in the sub-deep, deep layer (11-45 d) was 150% of that in the shallow layer (18-45 d). There was no significant difference in this ratio among these three layers (46-62 d) in the relatively stable stage. (3) There was no significant difference (P > 0.05) in the mineralization rate of SOC among the shallow, sub-deep, deep layers. The stability of SOC in the deep soil layer (100-400 cm) was similar to that in the shallow soil layer and the SOC in the deep soil layer was also involved in the global carbon cycle. The change of SOC in the deep soil layer should be taken into account when estimating the effects of soil carbon sequestration in the Hilly Region of the Loess Plateau, China.

Schottky barrier detection devices having a 4H-SiC n-type epitaxial layer

DOEpatents

Mandal, Krishna C.; Terry, J. Russell

2016-12-06

A detection device, along with methods of its manufacture and use, is provided. The detection device can include: a SiC substrate defining a substrate surface cut from planar to about 12.degree.; a buffer epitaxial layer on the substrate surface; a n-type epitaxial layer on the buffer epitaxial layer; and a top contact on the n-type epitaxial layer. The buffer epitaxial layer can include a n-type 4H--SiC epitaxial layer doped at a concentration of about 1.times.10.sup.15 cm.sup.-3 to about 5.times.10.sup.18 cm.sup.-3 with nitrogen, boron, aluminum, or a mixture thereof. The n-type epitaxial layer can include a n-type 4H--SiC epitaxial layer doped at a concentration of about 1.times.10.sup.13 cm.sup.-3 to about 5.times.10.sup.15 cm.sup.-3 with nitrogen. The top contact can have a thickness of about 8 nm to about 15 nm.

The Study Of Soil And Agrochemical Features Of Zonal Soils Of Coal Mining Enterprises In Kemerovo Region

NASA Astrophysics Data System (ADS)

Yakovchenko, M. A.; Kosolapova, A. A.; Ermolaev, V. A.

2017-01-01

The paper represents the results of the study of soil and agrochemical features of zonal soils: the grain-size composition, the content of humus, phosphorus and potassium, and heavy metals, the reaction of soil solution of the territory of the open-pit coal mine No12 of Kemerovo region in the areas of the working enterprise. The species composition of the lignose and herbaceous vegetation of the undisturbed territories has been studied. It has been revealed that the fertile soil layer of the studied areas of the open-pit coal mine is characterized as fertile but can’t be removed and stored because the surface of the whole area under study is forest-covered very much, rumpled, there are gullies and a lot of wind-fallen trees.

Microbial biomass and basal respiration of selected Sub-Antarctic and Antarctic soils in the areas of some Russian polar stations

NASA Astrophysics Data System (ADS)

Abakumov, E.; Mukhametova, N.

2014-07-01

Antarctica is a unique place for soil, biological, and ecological investigations. Soils of Antarctica have been studied intensively during the last century, when different national Antarctic expeditions visited the sixth continent with the aim of investigating nature and the environment. Antarctic investigations are comprised of field surveys mainly in the terrestrial landscapes, where the polar stations of different countries are situated. That is why the main and most detailed soil surveys were conducted in the McMurdo Valleys, Transantarctic Mountains, South Shetland Islands, Larsemann Hills and the Schirmacher Oasis. Our investigations were conducted during the 53rd and 55th Russian Antarctic expeditions in the base of soil pits, and samples were collected in Sub-Antarctic and Antarctic regions. Sub-Antarctic or maritime landscapes are considered to be very different from Antarctic landscapes due to differing climatic and geogenic conditions. Soils of diverse zonal landscapes were studied with the aim of assessing the microbial biomass level, basal respiration rates and metabolic activity of microbial communities. This investigation shows that Antarctic soils are quite diverse in profile organization and carbon content. In general, Sub-Antarctic soils are characterized by more developed humus (sod) organo-mineral horizons as well as by an upper organic layer. The most developed organic layers were revealed in peat soils of King George Island, where its thickness reach, in some cases, was 80 cm. These soils as well as soils formed under guano are characterized by the highest amount of total organic carbon (TOC), between 7.22 and 33.70%. Coastal and continental Antarctic soils exhibit less developed Leptosols, Gleysols, Regolith and rare Ornhitosol, with TOC levels between 0.37 and 4.67%. The metabolic ratios and basal respiration were higher in Sub-Antarctic soils than in Antarctic ones, which can be interpreted as a result of higher amounts of fresh organic remnants in organic and organo-mineral horizons. The soils of King George Island also have higher portions of microbial biomass (max 1.54 mg g-1) compared to coastal (max 0.26 mg g-1) and continental (max 0.22 mg g-1) Antarctic soils. Sub-Antarctic soils differ from Antarctic ones mainly by having increased organic layer thickness and total organic carbon content, higher microbial biomass carbon content, basal respiration, and metabolic activity levels.

Active layer monitoring at CALM-S site near J.G.Mendel Station, James Ross Island, eastern Antarctic Peninsula.

PubMed

Hrbáček, Filip; Kňažková, Michaela; Nývlt, Daniel; Láska, Kamil; Mueller, Carsten W; Ondruch, Jakub

2017-12-01

The Circumpolar Active Layer Monitoring - South (CALM-S) site was established in February 2014 on James Ross Island as the first CALM-S site in the eastern Antarctic Peninsula region. The site, located near Johann Gregor Mendel Station, is labelled CALM-S JGM. The grid area is gently sloped (<3°) and has an elevation of between 8 and 11ma.s.l. The lithology of the site consists of the muddy sediments of Holocene marine terrace and clayey-sandy Cretaceous sedimentary rocks, which significantly affect the texture, moisture content, and physical parameters of the ground within the grid. Our objective was to study seasonal and interannual variability of the active layer depth and thermal regime at the CALM-S site, and at two ground temperature measurement profiles, AWS-JGM and AWS-CALM, located in the grid. The mean air temperature in the period March 2013 to February 2016 reached -7.2°C. The mean ground temperature decreased with depth from -5.3°C to -5.4°C at 5cm, to -5.5°C to -5.9°C at 200cm. Active layer thickness was significantly higher at AWS-CALM and ranged between 86cm (2014/15) and 87cm (2015/16), while at AWS-JGM it reached only 51cm (2013/14) to 65cm (2015/16). The mean probed active layer depth increased from 66.4cm in 2013/14 to 78.0cm in 2014/15. Large differences were observed when comparing the minimum (51cm to 59cm) and maximum (100cm to 113cm) probed depths. The distribution of the active layer depth and differences in the thermal regime of the uppermost layer of permafrost at CALM-S JGM clearly show the effect of different lithological properties on the two lithologically distinct parts of the grid. Copyright © 2017 Elsevier B.V. All rights reserved.

The Effects of Light Intensity, Casing Layers, and Layering Styles on Royal Sun Medicinal Mushroom, Agaricus brasiliensis (Higher Basidiomycetes) Cultivation in Turkey.

PubMed

Adanacioglu, Neşe; Boztok, Kaya; Akdeniz, Ramazan Cengiz

2015-01-01

The aim of this research is to evaluate the effects of light intensity, casing layers, and layering styles on the production of the culinary-medicinal mushroom Agaricus brasiliensis in Turkey. The experiments were designed in split-split plots and replicated twice. Three different light intensities-I1, 350 lux; I2, 450 lux; and I3, 750 lux-were used in main plots as environmental factors. A mixture of 4 different casing layers- peat (100%), peat-perlite (75%:25%), peat-clinoptilolite (75%:25%), and peat-perlite-clinoptilolite (60%:20%:20%)-were used at split plots and at split plots. S1, a flat, 3-cm casing layer; S2, a flat, 5-cm casing layer; and S3, casing soil ridges 10 cm wide × 4 cm high, 10 cm apart, were deposited on top of 1-cm overall soil casing layers. At the end of the harvest phase, the total yield was estimated per 100 kg of substrate. Biological efficiency (percentage) was determined from the fresh weight of the mushrooms and the dry weight of the compost at the end of the harvesting period. The highest total yield (7.2 kg/100 kg compost) and biological efficiency (27.63%) were achieved from I2 × peat-perlite-clinoptilolite × S2 treatment. Influence of light intensity, casing layer, layering style, and their interaction in treatments with color values (L*, a*, b*, chroma*, and hue*) also were examined. It has been shown that within color values, chroma* (saturation) values of mushroom caps were affected by light intensity, casing layer, and layering style treatments and light intensity × casing layer treatments and the brightness of mushroom caps tended to increase as light intensity increased.

Assessment of agronomic homogeneity and compatibility of soils in the Vladimir Opolie region

NASA Astrophysics Data System (ADS)

Shein, E. V.; Kiryushin, V. I.; Korchagin, A. A.; Mazirov, M. A.; Dembovetskii, A. V.; Il'in, L. I.

2017-10-01

Complexes of gray forest soils of different podzolization degrees with the participation of gray forest podzolized soils with the second humus horizon play a noticeable role in the soil cover patterns of Vladimir Opolie. The agronomic homogeneity and agronomic compatibility of gray forest soils in automorphic positions ("plakor" sites) were assessed on the test field of the Vladimir Agricultural Research Institute. The term "soil homogeneity" implies in our study the closeness of crop yield estimates (scores) for the soil polygons; the term "soil compatibility" implies the possibility to apply the same technologies in the same dates for different soil polygons within a field. To assess the agronomic homogeneity and compatibility of soils, the statistical analysis of the yields of test crop (oats) was performed, and the spatial distribution of the particular parameters of soil hydrothermic regime was studied. The analysis of crop yields showed their high variability: the gray forest soils on microhighs showed the minimal potential fertility, and the maximal fertility was typical of the soils with the second humus horizon in microlows. Soils also differed significantly in their hydrothermic regime, as the gray forest soils with the second humus horizon were heated and cooled slower than the background gray forest soils; their temperature had a stronger lag effect and displayed a narrower amplitude in seasonal fluctuations; and these soils were wetter during the first weeks (40 days) of the growing season. Being colder and wetter, the soils with the second humus horizons reached their physical ripeness later than the gray forest soils. Thus, the soil cover of the test plot in the automorphic position is heterogeneous; from the agronomic standpoint, its components are incompatible.

Structure of a microbial community in soil after prolonged addition of low levels of simulated acid rain

PubMed

Pennanen; Fritze; Vanhala; Kiikkila; Neuvonen; Baath

1998-06-01

Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H2SO4, a combination of H2SO4 and HNO3, and HNO3 at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H+, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H2SO4 and HNO3 for the microbial community were not found.

Biodegradable multilayer barrier films based on alginate/polyethyleneimine and biaxially oriented poly(lactic acid).

PubMed

Gu, Chun-Hong; Wang, Jia-Jun; Yu, Yang; Sun, Hui; Shuai, Ning; Wei, Bing

2013-02-15

A layer-by-layer (LBL) approach was used to assemble alternating layers of sodium alginate (ALG)/polyethyleneimine (PEI) on biaxially oriented poly(lactic acid) (BOPLA) films in order to produce bio-based all-polymer thin films with low gas permeability. Increasing the depositing of ALG and PEI from 0 to 30 layers results in large thickness variations (from 0 to 3.92 μm). After 30 ALG/PEI layers are deposited, the resulting assembly has an OTR of 1.22 cm(3)/(m(2) day atm). When multiplied by thickness, the resulting oxygen permeability (OP) is found to be less than 3.8×10(-17) cm(3) cm/cm(2) s Pa, which is almost 3 orders of magnitude lower than that of uncoated BOPLA film (1.8×10(-14) cm(3)cm/cm(2) s Pa). At the same time, the resulting multilayer-coated BOPLA films maintain high optical clarity and tensile properties. This unique barrier thin film has become a promising alternative to non-biodegradable synthetic food packaging materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of the thickness of the anode electrode catalyst layers on the performance in direct methanol fuel cells

NASA Astrophysics Data System (ADS)

Glass, Dean E.; Olah, George A.; Prakash, G. K. Surya

2017-06-01

For the large scale fuel cell manufacture, the catalyst loading and layer thickness are critical factors affecting the performance and cost of membrane electrode assemblies (MEAs). The influence of catalyst layer thicknesses at the anode of a PEM based direct methanol fuel cell (DMFC) has been investigated. Catalysts were applied with the drawdown method with varied thicknesses ranging from 1 mil to 8 mils (1 mil = 25.4 μm) with a Pt/Ru anode loading of 0.25 mg cm-2 to 2.0 mg cm-2. The MEAs with the thicker individual layers (8 mils and 4 mils) performed better overall compared to the those with the thinner layers (1 mil and painted). The peak power densities for the different loading levels followed an exponential decrease of Pt/Ru utilization at the higher loading levels. The highest power density achieved was 49 mW cm-2 with the 4 mil layers at 2.0 mg cm-2 catalyst loading whereas the highest normalized power density was 116 mW mg-1 with the 8 mil layers at 0.25 mg cm-2 loading. The 8 mil drawdowns displayed a 50% and 23% increase in normalized power density compared to the 1 mil drawdowns at 0.25 mg cm-2 and 0.5 mg cm-2 loadings, respectively.

The copper spoil heap Knappenberg, Austria, as a model for metal habitats - Vegetation, substrate and contamination.

PubMed

Adlassnig, Wolfram; Weiss, Yasmin S; Sassmann, Stefan; Steinhauser, Georg; Hofhansl, Florian; Baumann, Nils; Lichtscheidl, Irene K; Lang, Ingeborg

2016-09-01

Historic mining in the Eastern Alps has left us with a legacy of numerous spoil heaps hosting specific, metal tolerant vegetation. Such habitats are characterized by elevated concentrations of toxic elements but also by high irradiation, a poorly developed substrate or extreme pH of the soil. This study investigates the distribution of vascular plants, mosses and lichens on a copper spoil heap on the ore bearing Knappenberg formed by Prebichl Layers and Werfener Schist in Lower Austria. It serves as a model for discriminating between various ecological traits and their effects on vegetation. Five distinct clusters were distinguished: (1) The bare, metal rich Central Spoil Heap was only colonised by highly resistant specialists. (2) The Northern and (3) Southern Peripheries contained less copper; the contrasting vegetation was best explained by the different microclimate. (4) A forest over acidic bedrock hosted a vegetation overlapping with the periphery of the spoil heap. (5) A forest over calcareous bedrock was similar to the spoil heap with regard to pH and humus content but hosted a vegetation differing strongly to all other habitats. Among the multiple toxic elements at the spoil heap, only Cu seems to exert a crucial influence on the vegetation pattern. Besides metal concentrations, irradiation, humidity, humus, pH and grain size distribution are important for the establishment of a metal tolerant vegetation. The difference between the species poor Northern and the diverse Southern Periphery can be explained by the microclimate rather than by the substrate. All plant species penetrating from the forest into the periphery of the spoil heap originate from the acidic but not from the calcareous bedrock. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical features of soils in a natural forest of West Hungary

NASA Astrophysics Data System (ADS)

Hofmann, Eszter; Bidló, András

2015-04-01

The present research focuses on the chemical results of soils formed on miocene carbonate rocks in a natural forest of West Hungary. Soil profiles derived from the Szárhalom Forest, located near the Lake Fertő, next to the city of Sopron. Six soil profiles were opened and analysed in this area. In the field the following physical parameters were evaluated from the soil profiles: transition, structure, compactness, roots, skeletal percent, colour, physical assortment, concretion and soil defect. Laboratory analysis involved the measurement of acidity, particle distribution, carbonated lime content, humus content, ammonium lactate-acetic acid soluble phosphorus- and potassium content, potassium chloride soluble calcium- and magnesium content, ethylene-diamine-tetraacetic-acid (EDTA) and diethylene-triamine-pentaacetic-acid (DTPA) soluble copper-, iron-, manganese- and zinc contents. These soils formed under a hornbeam-oak forest climate mainly and under a beech forest climate diffusely. The location and climate of the sites forms a basis of the comparison of the soils with similar base rock. The formation of the acidic and humus-rich upper layer of the soil profiles is influenced by the mineral composition and the weathering of the rocks. X-ray diffraction (Philips P W3710/PW1050 type X-ray diffractometer), thermoanalytical measurements (Mettler Toledo TGA/DSC 1 type thermogravimeter) and ICP-OES (Thermo Scientific iCAP 7000 Series) were also carried out to determine the mineral composition of the soils and the content of heavy metals. The soil samples were collected with both traditional and undisturbed (using the Kubiena box) sampling methods to enable further micromorphological investigations as well. The research is supported by the "Agroclimate-2" (VKSZ_12-1-2013-0034) joint EU-national research project. Key words: Natural forest, Miocene limestone, Mineral composition, Thermal analysis, Micromorphology

Ameliorants to immobilize Cd in rice paddy soils contaminated by abandoned metal mines in Korea.

PubMed

Ok, Yong Sik; Kim, Sung-Chul; Kim, Dong-Kuk; Skousen, Jeffrey G; Lee, Jin-Soo; Cheong, Young-Wook; Kim, Su-Jung; Yang, Jae E

2011-01-01

The cadmium (Cd) content of rice grain grown in metal-contaminated paddy soils near abandoned metal mines in South Korea was found to exceed safety guidelines (0.2 mg Cd kg⁻¹) set by the Korea Food and Drug Administration (KFDA). However, current remediation technologies for heavy metal-contaminated soils have limited application with respect to rice paddy soils. Laboratory and greenhouse experiments were conducted to assess the effects of amending contaminated rice paddy soils with zerovalent iron (ZVI), lime, humus, compost, and combinations of these compounds to immobilize Cd and inhibit Cd translocation to rice grain. Sequential extraction analysis revealed that treatment with the ameliorants induced a 50-90% decrease in the bioavailable Cd fractions when compared to the untreated control soil. When compared to the control, Cd uptake by rice was decreased in response to treatment with ZVI + humus (69%), lime (65%), ZVI + compost (61%), compost (46%), ZVI (42%), and humus (14%). In addition, ameliorants did not influence rice yield when compared to that of the control. Overall, the results of this study indicated that remediation technologies using ameliorants effectively reduce Cd bioavailability and uptake in contaminated rice paddy soils.

Particle size distribution in effluent of trickling filters and in humus tanks.

PubMed

Schubert, W; Günthert, F W

2001-11-01

Particles and aggregates from trickling filters must be eliminated from wastewater. Usually this happens through sedimentation in humus tanks. Investigations to characterize these solids by way of particle size measurements, image analysis and particle charge measurements (zeta potential) are made within the scope of Research Center for Science and Technology "Fundamentals of Aerobic biological wastewater treatment" (SFB 411). The particle size measuring results given within this report were obtained at the Ingolstadt wastewater treatment plant, Germany, which served as an example. They have been confirmed by similar results from other facilities. Particles flushed out from trickling filters will be partially destroyed on their way to the humus tank. A large amount of small particles is to be found there. On average 90% of the particles are smaller than 30 microm. Particle size plays a decisive role in the sedimentation behaviour of solids. Small particles need sedimentation times that cannot be provided in settling tanks. As a result they cause turbidity in the final effluent. Therefore quality of sewage discharge suffers, and there are hardly advantages of the fixed film reactor treatment compared to the activated sludge process regarding sedimentation behaviour.

Refine phosphorus stratification caused by long-term tillage and P fertilisation in maize -soybean rotation in eastern Canada

NASA Astrophysics Data System (ADS)

Ziadi, Noura; Morel, Christian

2017-04-01

The use of conservation tillage for crops production worldwide has increased markedly over recent years. Nutrient distributions under no-till (NT) compared with conventional moldboard tillage (CT) management in the cold, humid region of the eastern Canada need to be assessed for future placement, quantity, and type of fertilizers to efficiently match crop demands. We determined soil-profile distributions of soil total C (TC), total N (TN), and phosphate ions concentration (CP) in soil solution to a depth of 0.4 m after 23 years of continuous CT and NT management at different P fertilization rates on a clay loam soil in eastern Canada cropped with grain maize -soybean rotation. The experimental site was initiated in 1992 in southern Quebec, Canada. In August 2014, soil samples were collected at five profiles: 0 to 5, 5 to 10, 10 to 20, 20 to 30 and 30 to 40 cm under CT and NT fertilized at three P fertilizations (0 (P0), 17.5 (P0.5), and 35 (P1) kg P ha-1 applied as triple superphosphate on maize at 5 cm depth). To refine CNP stratification analysis for NT-P0 and NT-P1, supplemental soils of the 0-5 cm layer were sampled in P0 and P1 and then cutting into 5 layers of 1 cm. Different patterns for CP in relation to P fertilization under CT and NT were observed at the five profiles. The CP values did not differ significantly within ploughed layer but increased with P fertilization, e.g. 0.031, 0.066, and 0.075 mg P L-1 for P0, P0.5 and P1, respectively. Significant decline was observed in deeper depth beyond the plough. The Cp results in NT-P0 did not differ significantly to those of MP-P0. By contrast, highly significant P stratifications were observed in NT-P0.5 and NT-P1, especially marked in NT-P1 for which the CP value in 0-5 cm layer (0.35 mg P L-1) was 50 times greater than that in 30-40 cm layer (0.007 mg P L-1). To refine the C, N, and P stratifications, supplemental sampling was carried out in the 0-5 cm to cut this layer every 1 cm depth for P0 and P1. Most dramatic changes occurred within the 0-5 cm depth. The CP value in the first cm of soil (0.20 mg P L-1) was four times greater than that in the 4-5 cm layer (0.049 mg P L-1) of soil. The main reason for the large P accumulation in the first centimeter of soil is the annual return of plant residues to the soil surface. The stratification of TC and TN within the 0-5 cm layer showed similar trends irrespective of P fertilization. Under NT, the magnitude of CNP stratifications within the 0-1 cm layer to the 4-5 cm layer is equivalent to that observed in the 0-5 cm layer to the 30-40 cm layer.

HgCdTe Growth on 6 cm × 6 cm CdZnTe Substrates for Large-Format Dual-Band Infrared Focal-Plane Arrays

NASA Astrophysics Data System (ADS)

Reddy, M.; Peterson, J. M.; Lofgreen, D. D.; Vang, T.; Patten, E. A.; Radford, W. A.; Johnson, S. M.

2010-07-01

This paper describes molecular-beam epitaxy growth of mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) dual-band device structures on large-area (6 cm × 6 cm) CdZnTe substrates. Wafer-level composition and defect mapping techniques were used to investigate the limiting mechanisms in improving the cutoff wavelength ( λ c) uniformity and reducing the defect density. Structural quality of epitaxial layers was monitored using etch pit density (EPD) measurements at various depths in the epitaxial layers. Finally, 640 × 480, 20- μm-pixel-pitch dual-band focal-plane arrays (FPAs) were fabricated to demonstrate the overall maturity of growth and fabrication processes of epitaxial layers. The MWIR/LWIR dual-band layers, at optimized growth conditions, show a λ c variation of ±0.15 μm across a 6 cm × 6 cm CdZnTe substrate, a uniform low macrodefect density with an average of 1000 cm-2, and an average EPD of 1.5 × 105 cm-2. FPAs fabricated using these layers show band 1 (MWIR) noise equivalent temperature difference (NETD) operability of 99.94% and band 2 (LWIR) NETD operability of 99.2%, which are among the highest reported to date.

Mercury accumulation in the surface layers of mountain soils: a case study from the Karkonosze Mountains, Poland.

PubMed

Szopka, Katarzyna; Karczewska, Anna; Kabała, Cezary

2011-06-01

The study was aimed to examine total concentrations and pools of Hg in surface layers of soils in the Karkonosze Mountains, dependent on soil properties and site locality. Soil samples were collected from a litter layer and the layers 0-10 cm and 10-20 cm, at 68 sites belonging to the net of a monitoring system, in two separate areas, and in three altitudinal zones: below 900 m, 900-1100 m, and over 1100 m. Air-borne pollution was the major source of mercury in soils. Hg has accumulated mainly in the litter (where its concentrations were the highest), and in the layer 0-10 cm. Hg concentrations in all samples were in the range 0.04-0.97 mg kg(-1), with mean values 0.38, 0.28, and 0.14 mg kg(-1) for litter and the layers 0-10 cm and 10-20 cm, respectively. The highest Hg concentrations in the litter layer were found in the intermediate altitudinal zone, whereas Hg concentrations in the layer 0-10 cm increased with increasing altitude. Soil quality standard for protected areas (0.50 mg kg(-1)) was exceeded in a few sites. The pools of Hg accumulated in soils were in the range: 0.8-84.8 mg m(-2), with a mean value of 16.5 mg m(-2), and they correlated strongly with the pools of stored organic matter. Copyright © 2011 Elsevier Ltd. All rights reserved.

Energy value of soil organic matter and costs of its restoration

NASA Astrophysics Data System (ADS)

Kuczuk, Anna

2017-10-01

From the point of view of the sustainable soil management, the most important characteristic of soil organic matter (SOM) is associated with the energy content in it. This paper reports the results of an estimation of SOM resources and its energy value for the arable land in a selected farm. For this purpose, soil samples were taken in two fields from a soil depth profile of 30 cm. The testing regarding humus content were conducted at District Chemical and Agricultural Station in Opole. The study involved the assessment of organic matter content at a depth of 30 cm converted per 1 ha, energy value of the SOM resources and the theoretical energy potential was determined. In addition, an example of crop rotation was provided for the analyzed soils, which could be applicable in the process of restoring SOM resources. The cost of restoring the SOM resource was estimated and this value was compared with the energy value of fuel. The total cost of SOM restoration over the period of five years was equal to 3122.26-7845.86 PLN·ha-1 depending on the value of the lost revenue of commercial production, and simultaneously equal to the value of 6.2-16 Mg thermal coal.

AlGaN materials for semiconductor sensors and emitters in 200- to 365-nm range

NASA Astrophysics Data System (ADS)

Usikov, Alexander S.; Shapvalova, Elizaveta V.; Melnik, Yuri V.; Ivantsov, Vladimir A.; Dmitriev, Vladimir A.; Collins, Charles J.; Sampath, Anand V.; Garrett, Gregory A.; Shen, Paul H.; Wraback, Michael

2004-12-01

In this paper we report on the fabrication and characterization of GaN, AlGaN, and AlN layers grown by hydride vapor phase epitaxy (HVPE). The layers were grown on 2-inch and 4-inch sapphire and 2-inch silicon carbide substrates. Thickness of the GaN layers was varied from 2 to 80 microns. Surface roughness, Rms, for the smoothest GaN layers was less than 0.5 nm, as measured by AFM using 10 μm x 10 μm scans. Background Nd-Na concentration for undoped GaN layers was less than 1x1016 cm-3. For n-type GaN layers doped with Si, concentration Nd-Na was controlled from 1016 to 1019 cm-3. P-type GaN layers were fabricated using Mg doping with concentration Na-Nd ranging from 4x1016 to 3x1018 cm-3, for various samples. Zn doping also resulted in p-type GaN formation with concnetration ND-NA in the 1017 cm-3 range. UV transmission, photoluminescence, and crystal structure of AlGaN layers with AlN concentration up to 85 mole.% were studied. Dependence of optical band gap on AlGaN alloy composition was measured for the whole composition range. Thick (up to 75 microns) crack-free AlN layers were grown on SiC substrates. Etch pit density for such thick AlN layers was in the 107 cm-2 range.

[Effects of ex situ rice straw incorporation on organic matter content and main physical properties of hilly red soil].

PubMed

Zhu, Han-hua; Huang, Dao-you; Liu, Shou-long; Zhu, Qi-hong

2007-11-01

Two typical land-use types, i.e., newly cultivated slope land and mellow upland, were selected to investigate the effects of ex situ rice straw incorporation on the organic matter content, field water-holding capacity, bulk density, and porosity of hilly red soil, and to approach the correlations between these parameters. The results showed that ex situ incorporation of rice straw increased soil organic matter content, ameliorated soil physical properties, and improved soil water storage. Comparing with non-fertilization and applying chemical fertilizers, ex situ incorporation of rice straw increased the contents of organic matter (5.8%-28.9%) and > 0.25 mm water-stable aggregates in 0-20 cm soil layer, and increased the field water-holding capacity (6.8%-16.2%) and porosity (4.8%-7.7%) significantly (P < 0.05) while decreased the bulk density (4.5%-7.5%) in 10-15 cm soil layer. The organic matter content in 0-20 cm soil layer was significantly correlated to the bulk density, porosity, and field water-holding capacity in 10-15 cm soil layer (P < 0.01), and the field water-holding capacity in 0-20 cm and 10-15 cm soil layers was significantly correlated to the bulk density and porosity in these two layers (P < 0.05).

Mechanistic roles of soil humus and minerals in the sorption of nonionic organic compounds from aqueous and organic solutions

USGS Publications Warehouse

Chiou, C.T.; Shoup, T.D.; Porter, P.E.

1985-01-01

Mechanistic roles of soil humus and soil minerals and their contributions to soil sorption of nonionic organic compounds from aqueous and organic solutions are illustrated. Parathion and lindane are used as model solutes on two soils that differ greatly in their humic and mineral contents. In aqueous systems, observed sorptive characteristics suggest that solute partitioning into the soil-humic phase is the primary mechanism of soil uptake. By contrast, data obtained from organic solutions on dehydrated soil partitioning into humic phase and adsorption by soil minerals is influenced by the soil-moisture content and by the solvent medium from which the solute is sorbed. ?? 1985.

Fire and Thermal Effects of HD 1.3 Accidents: History, Research, and Analysis

DTIC Science & Technology

2010-07-01

consisted of a 1.3 cm thick steel plate (representing the external case), two layers of NBR rubber (representing case lining and ablative...1.3 cm steel plate, 2 layers of NBR rubber , 2.5 cm PMMA • Nitrogen co-flow to prevent ignition of NBR layers • 1D HEATING for prediction 0 200 400...and 100 kW/m 2 . The NBR layers will pyrolyze at elevated temperatures. In a real motor, those gases would be contained by the pressure tight case

Bi-layer channel structure-based oxide thin-film transistors consisting of ZnO and Al-doped ZnO with different Al compositions and stacking sequences

NASA Astrophysics Data System (ADS)

Cho, Sung Woon; Yun, Myeong Gu; Ahn, Cheol Hyoun; Kim, So Hee; Cho, Hyung Koun

2015-03-01

Zinc oxide (ZnO)-based bi-layers, consisting of ZnO and Al-doped ZnO (AZO) layers grown by atomic layer deposition, were utilized as the channels of oxide thin-film transistors (TFTs). Thin AZO layers (5 nm) with different Al compositions (5 and 14 at. %) were deposited on top of and beneath the ZnO layers in a bi-layer channel structure. All of the bi-layer channel TFTs that included the AZO layers showed enhanced stability (Δ V Th ≤ 3.2 V) under a positive bias stress compared to the ZnO single-layer channel TFT (Δ V Th = 4.0 V). However, the AZO/ZnO bi-layer channel TFTs with an AZO interlayer between the gate dielectric and the ZnO showed a degraded field effect mobility (0.3 cm2/V·s for 5 at. % and 1.8 cm2/V·s for 14 at. %) compared to the ZnO single-layer channel TFT (5.5 cm2/V·s) due to increased scattering caused by Al-related impurities near the gate dielectric/channel interface. In contrast, the ZnO/AZO bi-layer channel TFTs with an AZO layer on top of the ZnO layer exhibited an improved field effect mobility (7.8 cm2/V·s for 14 at. %) and better stability. [Figure not available: see fulltext.

Improved electron injection in all-solution-processed n-type organic field-effect transistors with an inkjet-printed ZnO electron injection layer

NASA Astrophysics Data System (ADS)

Roh, Jeongkyun; Kim, Hyeok; Park, Myeongjin; Kwak, Jeonghun; Lee, Changhee

2017-10-01

Interface engineering for the improved injection properties of all-solution-processed n-type organic field-effect transistors (OFETs) arising from the use of an inkjet-printed ZnO electron injection layer were demonstrated. The characteristics of ZnO in terms of electron injection and transport were investigated, and then we employed ZnO as the electron injection layer via inkjet-printing during the fabrication of all-solution-processed, n-type OFETs. With the inkjet-printed ZnO electron injection layer, the devices exhibited approximately five-fold increased mobility (0.0058 cm2/V s to 0.030 cm2/V s), more than two-fold increased charge concentration (2.76 × 1011 cm-2 to 6.86 × 1011 cm-2), and two orders of magnitude reduced device resistance (120 MΩ cm to 3 MΩ cm). Moreover, n-type polymer form smoother film with ZnO implying denser packing of polymer, which results in higher mobility.

Modelling of active layer thickness evolution on James Ross Island in 2006-2015

NASA Astrophysics Data System (ADS)

Hrbáček, Filip; Uxa, Tomáš

2017-04-01

Antarctic Peninsula region has been considered as one of the most rapidly warming areas on the Earth. However, the recent studies (Turner et al., 2016; Oliva et al., 2017) showed that significant air temperature cooling began around 2000 and has continued until present days. The climate cooling led to reduction of active layer thickness in several parts of Antarctic Peninsula region during decade 2006-2015, but the information about spatiotemporal variability of active layer thickness across the region remains largely incoherent due to lack of active layer temperature data from deeper profiles. Valuable insights into active layer thickness evolution in Antarctic Peninsula region can be, however, provided by thermal modelling techniques. These have been widely used to study the active layer dynamics in different regions of Arctic since 1990s. By contrast, they have been employed much less in Antarctica. In this study, we present our first results from two equilibrium models, the Stefan and Kudryavtsev equations, that were applied to calculate the annual active layer thickness based on ground temperature data from depth of 5 cm on one site on James Ross Island, Eastern Antarctic Peninsula, in period 2006/07 to 2014/15. Study site (Abernethy Flats) is located in the central part of the major ice-free area of James Ross Island called Ulu Peninsula. Monitoring of air temperature 2 m above ground surface and ground temperature in 50 cm profile began on January 2006. The profile was extended under the permafrost table down to 75 cm in February 2012, which allowed precise determination of active layer thickness, defined as a depth of 0°C isotherm, in period 2012 to 2015. The active layer thickness in the entire observation period was reconstructed using the Stefan and Kudryavtsev models, which were driven by ground temperature data from depth of 5 cm and physical parameters of the ground obtained by laboratory analyses (moisture content and bulk density) and calculations from ground heat flux measurement (thermal conductivity and thermal capacity). Model results were validated using the reference active layer thicknesses from the summer seasons of 2012/13 to 2014/15 with very good accuracy of 0 to 4 cm and -4 to 1 cm for the Stefan and the Kudryavtsev models, respectively. Average active layer thickness on Abernethy Flats varied between 62 cm (Stefan model) and 60 cm (Kudryavtsev model) in period 2006/07-2014/15. Both models showed average active layer thinning of -1.3 cm.year-1 (Stefan model) and -2.3 cm.year-1 (Kudryavtsev model). Maximum active layer thickness was predicted in summer season 2008/09, reaching 75 cm (Stefan model) and 83 cm (Kudryavtsev model), while the minimum active layer thickness was observed in summer season 2009/10 when both models predicted 36 cm. Our results show that both models are well suited for conditions of Antarctica because their accuracy is in the order of the first centimetres. The nine-year series confirmed thinning of active layer in this part of Antarctic Peninsula region, which was mainly related to variability of summer air temperature. References: Turner, J., Lu, H., White, I., King, J. C., Phillips, T., Scott Hosking, J. Bracegirdle, T. J.,Marshall, G. J., Mulvaney, R., Deb, P., 2016. Absence of 21st century warming on Antarctic Peninsula consistent with natural variability. Nature 535, doi: 10.1038/nature18645 Oliva, M., Navarro, F., Hrbáček, F., Hernandéz, A., Nývlt, D., Perreira, P., Ruiz-Fernandéz, J., Trigo, R., in press. Recent regional climate cooling on the Antarctic Peninsula and associated impacts on the cryosphere. Science of Total Environment. dx.doi.org/10.1016/j.scitotenv.2016.12.030

Ericoid Roots and Mycospheres Govern Plant-Specific Bacterial Communities in Boreal Forest Humus.

PubMed

Timonen, Sari; Sinkko, Hanna; Sun, Hui; Sietiö, Outi-Maaria; Rinta-Kanto, Johanna M; Kiheri, Heikki; Heinonsalo, Jussi

2017-05-01

In this study, the bacterial populations of roots and mycospheres of the boreal pine forest ericoid plants, heather (Calluna vulgaris), bilberry (Vaccinium myrtillus), and lingonberry (Vaccinium vitis-idaea), were studied by qPCR and next-generation sequencing (NGS). All bacterial communities of mycosphere soils differed from soils uncolonized by mycorrhizal mycelia. Colonization by mycorrhizal hyphae increased the total number of bacterial 16S ribosomal DNA (rDNA) gene copies in the humus but decreased the number of different bacterial operational taxonomic units (OTUs). Nevertheless, ericoid roots and mycospheres supported numerous OTUs not present in uncolonized humus. Bacterial communities in bilberry mycospheres were surprisingly similar to those in pine mycospheres but not to bacterial communities in heather and lingonberry mycospheres. In contrast, bacterial communities of ericoid roots were more similar to each other than to those of pine roots. In all sample types, the relative abundances of bacterial sequences belonging to Alphaproteobacteria and Acidobacteria were higher than the sequences belonging to other classes. Soil samples contained more Actinobacteria, Deltaproteobacteria, Opitutae, and Planctomycetia, whereas Armatimonadia, Betaproteobacteria, Gammaproteobacteria, and Sphingobacteriia were more common to roots. All mycosphere soils and roots harbored bacteria unique to that particular habitat. Our study suggests that the habitation by ericoid plants increases the overall bacterial diversity of boreal forest soils.

Relationship between assimilable-nutrient content and physicochemical properties of topsoil

NASA Astrophysics Data System (ADS)

Tkaczyk, Przemysław; Bednarek, Wiesław; Dresler, Sławomir; Krzyszczak, Jaromir; Baranowski, Piotr; Sławiński, Cezary

2017-10-01

In the years 2008-2011, an environmental study was conducted for Polish soils, focusing on the south-eastern Poland soils, as they exhibit significant acidification. This study aimed at assessing the current pHKCl and the supply of basic macro- (P, K, Mg and S-SO4) and microelements (B, Cu, Fe, Mn and Zn) in the collected soil samples, and also at determining their relationship with the soil agronomic category, humus content and pH class. Soil reaction and humus and macronutrient content were positively correlated with the amount of colloidal clay and particles < 0.02 mm. In the majority of cases, the macro-element content in the soil was positively correlated with soil pH and humus content. As for microelements, a usually significant and positive correlation was found between the soil agronomic category and the content of manganese, iron and zinc, whereas for the content of boron and copper, no such relationship was observed. A significant and positive correlation between soil reaction and the content of manganese, iron and boron was also found. Such correlations were not observed in relation to copper and zinc content. Statistical analysis indicated that the content of boron and manganese depended to the greatest extent on the investigated physicochemical properties.

Soils of the Summer Garden (Saint Petersburg)

NASA Astrophysics Data System (ADS)

Matinyan, N. N.; Bakhmatova, K. A.; Korentsvit, V. A.

2017-06-01

Soils of the Summer Garden—the first regular (French-style) garden in Russia—are characterized on the basis of the materials of field study performed during reconstruction of the garden in 2005-2011. Most of these soils are filled soils—urbostratozems—underlain by the loamy sands deposited in the Littorina Sea or by the buried gray-humus gleyic and gleyed soils. Urbostratozems are characterized by the slightly acid reaction in the topsoil horizons and slightly alkaline reaction in the middle-profile and lower horizons. The humus content in them varies from 0.2 to 6.8%; in the buried gray-humus soils, it is within 1.3-2.6%. The soils of the garden are characterized by the high and extremely high content of available phosphorus and the predominantly low content of available potassium as determined by Machigin's method. The bulk content of Pb in the surface soil horizons during the period of our study exceeded the maximum permissible concentration by 3-20 times; the bulk contents of Cu and Zn exceeded the tentative permissible concentrations for coarse-textured soils by 2-6 and 4-20 times, respectively. The main sources of the soil contamination by the heavy metals are the nearby highways. Local contaminated area was also found near the household yard.

The mesofauna in different types of soils under southern taiga spruce forests (Tver oblast)

NASA Astrophysics Data System (ADS)

Gryuntal, S. Yu.

2010-11-01

The soil mesofauna of the burozem, soddy pale-podzolic, and whitish-podzolic soils under three types of southern taiga spruce forests was studied. The mesofauna of all these soils turned out to be similar in terms of the Chilopoda, Staphylinidae (Coleoptera), and Rhagionidae (Diptera) numbers and their predominant concentration in the litter. The zoophages prevailed, and, among the saprophages, primary destroyers were predominant. However, some specific characteristics of the mesofauna in the soils studied were revealed. In the sequence burozem, soddy pale-podzolic, and whitish-podzolic soils, the number of earthworms significantly decreased, while, in the sequence soddy pale-podzolic, burozem, and whitish-podzolic soils, the number of Diplopoda representatives and calciphilic forms became lower and was directly related to the diversity of the deciduous tree species and to the presence of the calcareous moraine close to the surface. In addition, some species can be indicators of particular soil properties. The presence of the road beetle Quedius fuliginosus indicated the elevated moisture of the soils, that of Philonthus decorus pointed to the high humus content, and the presence of the road beetle Tachinus marginellus showed the low acidity of the humus. The low number or the absence of the earthworms Octolasium lacteum and Dendrodril us rubidus f. tenuis indicated higher humus acidity.

Quality improvement of laminated board made from oil palm trunk at various outer layer using phenol formaldehyde adhesive

NASA Astrophysics Data System (ADS)

Hartono, R.; Sucipto, T.

2018-02-01

Characteristic of laminated board from oil palm trunk (OPT) is very low in quality. The effort to improved it’s quality done by using the outer layer from high density wood. The purpose of this experiment was to analyzed the effects of the outer layer on physical and mechanical properties of OPT and to obtain optimum treatment to fulfills JAS 234:2003. All of laminated board was made of 3 layers, and for the middle layer was made by densified-OPT. Then for the outer layer was made of sengon and meranti wood. The sample size was 5 cm (width) × 3 cm (thick) × 45 cm (length). The various outer layer of laminated board were A (OPT/densified OPT/OPT); B (Sengon/densified OPT/OPT); C (Sengon/densified OPT/sengon); D (Meranti/densified OPT/OPT) and E (Meranti/densified OPT/meranti). The results showed that the moisture content, density, thickness swelling, delamination, MOR and MOE were 6.10-8.48%; 0.40-0.63 g/cm3; 6.43-13.20%; 0%; 168.79-438.29 kg/cm2 and 30115-100454 kg/cm2, respectively. The moisture content and delamination fulfills JAS 234:2003, while density and thickness swelling did not fulfill standard. Whereas for MOR and MOE value, only type D and E that fulfill standard. There are strongth relationship between density and mechanical properties, such as MOR and MOE value. The optimum treatment in this reseach to made laminated board made from OPT was type D that using the meranti as outer layer.

[Effect of long-term fertilization on microbial community functional diversity in black soil].

PubMed

Liu, Jing-xin; Chi, Feng-qin; Xu, Xiu-hong; Kuang, En-jun; Zhang, Jiu-ming; Su, Qing-rui; Zhou, Bao-ku

2015-10-01

In order to study the effects of long-term different fertilization on microbial community functional diversity in arable black. soil, we examined microbial metabolic activities in two soil la- yers (0-20 cm, 20-40 cm) under four treatments (CK, NPK, M, MNPK) from a 35-year continuous fertilization field at the Ministry of Agriculture Key Field Observation Station of Harbin Black Soil Ecology Environment using Biolog-ECO method. The results showed that: in the 0-20 cm soil layer, combined application of organic and inorganic fertilizer(MNPK) increased the rate of soil microbial carbon source utilization and community metabolism richness, diversity and dominance; In the 20-40 cm layer, these indices of the MNPK treatment was lower than that of the NPK treat- ment; while NPK treatment decreased soil microbial community metabolism evenness in both layers. Six groups of carbon sources used by soil microbes of all the treatments were different between the two soil layers, and the difference was significant among all treatments in each soil layer (P < 0.05) , while the variations among treatments were different in the two soil layers. Canonical correspondence analysis (CCA) showed that soil microbial community metabolic function of all the treatments was different between the two soil layers, and there was difference among all treatments in each soil layer, while the influences of soil nutrients on soil microbial community metabolic function of all treatments were similar in each soil layer. It was concluded that long-term different fertilization affected soil microbial community functional diversity in both tillage soil layer and down soil layers, and chemical fertilization alone had a larger influence on the microbial community functional diversity in the 20-40 cm layer.

[Changes of soil physical properties during the conversion of cropland to agroforestry system].

PubMed

Wang, Lai; Gao, Peng Xiang; Liu, Bin; Zhong, Chong Gao; Hou, Lin; Zhang, Shuo Xin

2017-01-01

To provide theoretical basis for modeling and managing agroforestry systems, the influence of conversion of cropland to agroforestry system on soil physical properties was investigated via a walnut (Juglans regia)-wheat (Triticum aestivum) intercropping system, a wide spreading local agroforestry model in northern Weihe River of loess area, with the walnut and wheat monoculture systems as the control. The results showed that the improvement of the intercropping system on soil physical properties mainly appeared in the 0-40 cm soil layer. The intercropping system could prevent soil bulk density rising in the surface soil (0-20 cm), and the plow pan in the 20-40 cm soil layer could be significantly alleviated. The intercropping system had conti-nuous improvement on soil field capacity in each soil layer with the planting age increase, and the soil field capacity was higher than that of each monoculture system in each soil layer (except 20-40 cm soil layer) since the 5th year after planting. The intercropping system had continuous improvement on soil porosity in each soil layer, but mainly in the 0-20 and 20-40 cm soil layer, and the ratio of capillary porosity was also improved. The soil bulk density, field capacity and soil porosity obtained continuous improvement during the conversion of cropland to agroforestry system, and the improvement on soil physical properties was stronger in shallow soil layer than in deep soil.

[Change characteristics of soil moisture and nutrients in rain-fed winter wheat field under different fertilization modes in Southern Shanxi of China during summer fallow period].

PubMed

Li, Ting-Liang; Xie, Ying-He; Hong, Jian-Ping; Feng, Qian; Sun, Cheng-Hong; Wang, Zhi-Wei

2013-06-01

In 2009-2011, a field experiment was conducted in a rain-fed winter wheat field in Southern Shanxi of China to study the effects of different fertilization modes on the change characteristics of soil moisture and nitrate-N contents in 0-200 cm layer and of soil available phosphorus (Oslen-P) and potassium contents in 0-40 cm layer during summer fallow period (from June to September). Three fertilization modes were installed, i. e., conventional fertilization (CF), recommended fertilization (RF), and ridge film furrow planting (RFFP) combined with straw mulch. The results showed that the rainfall in summer fallow period could complement the consumed water in 0-200 cm soil layer in dryland wheat field throughout the growth season, and more than 94% of the water storage was in 0-140 cm soil layer, with the fallow efficiency ranged from 6% to 27%. The rainfall in summer fallow period caused the soil nitrate-N moving downward. 357-400 mm rainfall could make the soil nitrate-N leaching down to 100 cm soil layer, with the peak in 20-40 cm soil layer. Straw mulching or plastic film with straw mulch in summer fallow period could effectively increase the Oslen-P and available K contents in 0-40 cm soil layer, and the accumulative increment in three summer fallow periods was 16-45% and 36-49%, respectively. Among the three modes, the binary coverage mode of RFFP plus furrow straw mulching had the best effect in maintaining soil water and fertility. The accumulative water storage and mineral N in 0-200 cm soil layer in three summer fallow periods were up to 215 mm and 90 kg x hm(-2), and the accumulative Oslen-P and available K contents in plough layer were increased by 2.7 mg x kg(-1) and 83 mg x kg(-1), respectively, being significantly higher than those in treatments CF and RF. There were no significant differences in the change characteristics in the soil moisture and nutrients between treatments CF and RF.

X-ray reflectivity of ruthenium nano-oxide layer in a CoFe-Ru-CoFe trilayer system

NASA Astrophysics Data System (ADS)

Asghari Zadeh, Saeid; Sutton, Mark; Altonian, Zaven; Mao, Ming; Lee, Chih-Ling

2006-03-01

A grazing incidence X-ray reflectivity technique is used to determine electron density profile(EDP) as a function of depth in CoFe-Ru-CoFe and CoFe-Ru nano oxide layer(NOL)-CoFe trilayers. Four trilayers with ruthenium thicknesses of 8,8.5 and 9 å.08cm and one with Ru8.5.05cmå.05cmNOL, prepared by a dc planetary sputtering system, were investigated. For all samples, EDP shows a central peak which is related to the Ru layer. Natural oxidation in all samples introduces a graded EDP of the top CoFe layer that decreases gradually to zero. The large surface resistivity of Ru8.5 å.05cm NOL compared to Ru 8.5å.08cm can be related to the remarkable difference between their EDP.

Iron Compounds and the Color of Soils in the Sakhalin Island

NASA Astrophysics Data System (ADS)

Vodyanitskii, Yu. N.; Kirillova, N. P.; Manakhov, D. V.; Karpukhin, M. M.

2018-02-01

Numerical parameters of soil color were studied according to the CIE-L*a*b color system before and after the Tamm's and Mehra-Jackson's treatments; we also determined the total Fe content in the samples from the main genetic horizons of the alluvial gray-humus soil, two profiles of burozems, and two profiles of podzols in the Sakhalin Island. In the analyzed samples, the numerical color parameters L* (lightness), a* (redness) and b* (yellowness) are found to vary within 46-73, 3-11, and 8-28, respectively. A linear relationship is revealed between the numerical values of a* parameters and Fe content in the Mehra-Jackson extracts; the regression equations are derived with the determination coefficients ( R 2): 0.49 (typical burozem), 0.79 (podzolized burozem), 0.96 (shallow-podzolic mucky podzol), 0.98 (gray-humus gley alluvial soil). For the surface-podzolic mucky podzol contaminated with petroleum hydrocarbons, R 2 was equal to only 0.03. In the gray humus (AY) and structural-metamorphic (BM) horizons of the studied soils, a* and b* parameters decrease after their treatment with the Tamm's reagent by 2 points on average. After the Mehra-Jackson treatment, the a* parameter decreased by 6 (AY) and 8 (BM) points; whereas b* parameter, by 10 and 15 points, respectively. In the E horizons of podzols, the Tamm's treatment increased a* and b* parameters by 1 point; whereas the Mehra-Jackson's treatment decreased these parameters by only 1 and 3 points, respectively. The redness (a*) decreased maximally in the lower gley horizon of the alluvial gray humus soil, i.e., by 6 (in the Tamm's extract) and 10 points (in the Mehra-Jackson's) extract. Yellowness (b*) decreased by 12 and 17 points, respectively. The revealed color specifics in the untreated samples and the color transformation under the impact of reagents in the studied soils and horizons may serve as an additional parameter that characterizes quantitatively the object of investigation in the reference databases.

Effect of mismanagement at the state of organic matter in soil

NASA Astrophysics Data System (ADS)

Hladký, Jan; Elbl, Jakub; Kynický, Jindřich; Dvořáčková, Helena; Juřička, David; Pecina, Václav; Brtnický, Martin

2017-04-01

Organic matter is an essential part of the soil. It affects the physical, chemical, and biological properties of the soil. It is therefore necessary to maintain organic matter in the soil and its quality as the prevention of soil degradation. Loss of organic matter is in the Czech Republic threatened up to 45% of arable soil. The most important reason for the loss of organic matter in the soil is poor management, especially improper crop rotation, cultivation of erosion-prone crops where erosion takes away valuable topsoil with nutrients and organic matter. The aim of our study was to verify the influence of inappropriate management on selected 5 plots in southern Moravia in the Czech Republic. It is the region with the highest incidence of water erosion in the Czech Republic. Were selected plots with significantly sloping, where corn was grown. Samples were taken in the autumn after the harvest, each of topsoil. The sampling sites were placed in positions on the slope where soil was not damaged by erosion, as well as the place greatest damage and the place where washed soil was accumulated. Soil average humus content was for undamaged position on the slope 1.93% and 0.84 quality, the most heavily damaged part of the slope humus content dropped to 1.35% and its quality at only 0.56. In the case of position of accumulated soils was found the average amount of humus 1.70% and 0.90 quality. Humus content and its quality is statistically significantly influenced by water erosion (α = 0.05). The study showed that bad management, when there is not crop rotation adapted to the given conditions and not subjected to any suitable soil-protecting technologies, there is significant damage to soils, which shows mainly organic matter decline and a decline in its quality. Continuation of our study will verify the possibility of stabilization of soil organic matter and draft appropriate technologies.

Raman study of supported molybdenum disulfide single layers

NASA Astrophysics Data System (ADS)

Durrer, William; Manciu, Felicia; Afanasiev, Pavel; Berhault, Gilles; Chianelli, Russell

2008-10-01

Owing to the increasing demand for clean transportation fuels, highly dispersed single layer transition metal sulfides such as MoS2-based catalysts play an important role in catalytic processes for upgrading and removing sulfur from heavy petroleum feed. In its crystalline bulk form, MoS2 is chemically rather inactive due to a strong tendency to form highly stacked layers, but, when dispersed as single-layer nanoclusters on a support, the MoS2 becomes catalytically active in the hydrogenolysis of sulphur and nitrogen from organic compounds (hydrotreating catalysis). In the present studies alumina-supported MoS2 samples were analyzed by confocal Raman spectroscopy. Evidence of peaks at 152 cm-1, 234 cm-1, and 336 cm-1, normally not seen in the Raman spectrum of the standard bulk crystal, confirms the formation of single layers of MoS2. Furthermore, the presence of the 383 cm-1 Raman line suggests the trigonal prismatic coordination of the formed MoS2 single layers. Depending on the sample preparation method, a restacking of MoS2 layers is also observed, mainly for ex-thiomolybdate samples sulfided at 550 C.

Characterization of the humic substances isolated from postfire soils of scotch pine forest in Togljatty city, Samara region by the 13C-NMR spectroscopy

NASA Astrophysics Data System (ADS)

Maksimova, Ekaterina; Abakumov, Evgeny

2016-04-01

Postpyrogenic soil dynamics is an informative tool for studying of soil elementary processes in extreme temperature conditions and for predicting of short time environmental changes in conditions of catastrophic landscape changes. Soil organic matter (SOM) system evolution is the most rapid process of postpyrogenic soil development. In this relation the evaluation of humus accumulation rates and humification trend were conducted with use of the classical chemical and modern spectroscopy methods. Soil restoration after spontaneous forest fires near Togljatty city (Samara region, Russia) was abandoned in 2010, and further monitoring over the next four years was organized to evaluate the speed of biogenic processes and humus accumulation dynamics. Three key soil plots were studied for estimating SOM quality changes under the forest fire effect: surface forest fire, crown forest fire and control. Total carbon and nitrogen content as well as Cha/Cfa ratios (content of humic acids/ content of fulvic acids), were estimated to assess the dynamics of soil restoration. Humic acid powders were extracted and analyzed by elemental composition and 13C-NMR spectroscopy to assess changes in humic substance structure and composition. The data obtained indicate that burning of a forest floor and sod (humic) horizon led to humus losses and decreases in total carbon stocks. As a result of the fires, the content of humic acids in the pyrogenic horizon increased, leading alterations of humus type. Greater increases in the degree of organic matter humification were observed for surface fires than crown fires. It was shown that the humus molecular composition was substantially affected by the wildfires. The data show an increase in aromaticity, a loss of oxygen-containing groups and dehydrogenation of humic acids. Humic acids in the soils of the control plots and after wildfires were significantly different, especially in the ratios of hydrogen, oxygen and carbon. The increase in the degree of humic acid aromatization was confirmed by the hydrogen/carbon ratio. Investigation of the humic acids' molecular structure by 13C-NMR showed a relative increase in aromatic compounds and decrease in aliphatic ones. In general, crown and surface fires plots are not very different in terms of 13C-NMR spectra of humic acids, however humic acids of control plot have essential differences from pyrogenic ones. This study was a contribution to the Russian foundation for basic research, project for young scientists No.14-04-32132 and 15-34-20844.

Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements.

PubMed

Baize, D; Sterckeman, T

2001-01-08

In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than that which would be encountered in most soils of Switzerland and France. Given this evaluation of the background content, it seems that only the surface horizons have been affected by Zn contamination (an addition of approx. 60-100 mg kg(-1)). In the case of Cd, the increase in concentrations is only 0.5-1 mg kg(-1) for the ploughed horizons, as well as the for the A horizons.

[Characteristics of organic carbon forms in the sediment of Wuliangsuhai and Daihai Lakes].

PubMed

Mao, Hai-Fang; He, Jiang; Lü, Chang-Wei; Liang, Ying; Liu, Hua-Lin; Wang, Feng-Jiao

2011-03-01

The characteristics and differences of organic carbon forms in the sediments of the Wuliangsuhai and the Daihai Lakes with different eutrophication types were discussed in the present study. The results showed that the range of total organic carbon content (TOC) in Wuliangsuhai Lake was 4.50-22.83 g x kg(-1) with the average of 11.80 g x kg(-1). The range of heavy-fraction organic carbon content was 3.38-21.67 g x kg(-1) with the average of 10.76 g x kg(-1). The range of light-fraction organic carbon content was 0.46-1.80 g x kg(-1) with the average of 1.04 g x kg(-1); The range of ROC content was 0.62-3.64 g x kg(-1) with the average of 2.11 g x kg(-1), while the range of total organic carbon content in Daihai lake was 6.84-23.46 g x kg(-1) with the average of 14.94 g x kg(-1). The range of heavy-fraction organic carbon content was 5.27-22.23 g x kg(-1) with the average of 13.89 g x kg(-1). The range of light-fraction organic carbon content was 0.76-1.57 g x kg(-1). The range of ROC content was 1.54-7.08 g x kg(-1) with the average of 3.62 g x kg(-1). The results indicated that the heavy-fraction organic carbon was the major component of the organic carbon and plays an important role in the accumulation of organic carbon in the sediments of two Lakes. The content of light-fraction organic carbon was similar in the sediments of two lakes, whereas, the contents of total organic carbon and heavy-fraction organic carbon in the sediment of Wuliangsuhai Lake were less than those in the sediment of Daihai Lake, and the value of LFOC/TOC in the Wuliangsuhai Lake was larger than that in the Daihai Lake. The humin was the dominant component of the sediment humus, followed by fulvic acid in the two lakes. The values of HM/HS in the sediments of Wuliangsuhai lake range from 43.06% to 77.25% with the average of 62.15% and values of HM/HS in the sediments of Dahai lake range from 49.23% to 73.85% with the average of 65.30%. The tightly combined humus was the dominant form in the sediment humus of two lakes, and the followed was loosely combined humus. As a whole, the carbon storage of two lakes were all relatively stable, but the values of PQ, LFOC/TOC, the ratio of loosely to tightly combined humus and HA/FA revealed that, in the sediment of Wuliangsuhai, the humification degree of organic matter was lower than that of Daihai, while the activity of humus was higher than that of Daihai, thus the carbon storage is less stable than that of Daihai.

The interactions between tree-herb layer diversity and soil properties in the oriental beech (Fagus orientalis Lipsky) stands in Hyrcanian forest.

PubMed

Bakhshandeh-Navroud, Behzad; Abrari Vajari, Kambiz; Pilehvar, Babak; Kooch, Yahya

2018-06-26

This study investigated the interactions between tree-herb layer diversity and some physico-chemical and eco-physiological characteristics of soil in natural oriental beech stand in western Guilan, Iran. The data were collected from nine research sites (50 m × 50 m) which were described as a gradient from pure oriental beech (Fagus orientalis Lipsky) stands to mixed stands with up to nine deciduous tree species (n = 27) in Hyrcanian forest. Herbaceous plants were sampled within ten 1 m × 1 m sub-plots in two plots of 400 m 2 which were installed randomly in each research site. Composite soil samples were taken at five positions in each research site. We found that the increase in tree diversity in mature oriental beech stands brought about an increase in microbial biomass carbon, soil carbon content, and the ratio of microbial biomass carbon to the organic carbon (C mic /C org ). Increased soil organic carbon raised microbial biomass carbon through creating suitable environment for microorganisms. The findings also indicated that the ratio of microbial biomass carbon to the organic carbon (C mic /C org ) increased as a quantitative indicator of soil carbon dynamics that finally benefits soil fertility of mixed oriental beech stands compared to pure oriental beech stands. The results showed that humus layer and litter thickness were negatively correlated with tree layer richness. Generally, it can be stated that maintaining a mixture of tree layer species in natural oriental beech stands results in an increase in richness and diversity values of herb plants as well as carbon content and microbial biomass carbon of soil.

Soil moisture dynamics and dominant controls at different spatial scales over semiarid and semi-humid areas

NASA Astrophysics Data System (ADS)

Suo, Lizhu; Huang, Mingbin; Zhang, Yongkun; Duan, Liangxia; Shan, Yan

2018-07-01

Soil moisture dynamics plays an active role in ecological and hydrological processes, and it depends on a large number of environmental factors, such as topographic attributes, soil properties, land use types, and precipitation. However, studies must still clarify the relative significance of these environmental factors at different soil depths and at different spatial scales. This study aimed: (1) to characterize temporal and spatial variations in soil moisture content (SMC) at four soil layers (0-40, 40-100, 100-200, and 200-500 cm) and three spatial scales (plot, hillslope, and region); and (2) to determine their dominant controls in diverse soil layers at different spatial scales over semiarid and semi-humid areas of the Loess Plateau, China. Given the high co-dependence of environmental factors, partial least squares regression (PLSR) was used to detect relative significance among 15 selected environmental factors that affect SMC. Temporal variation in SMC decreased with increasing soil depth, and vertical changes in the 0-500 cm soil profile were divided into a fast-changing layer (0-40 cm), an active layer (40-100 cm), a sub-active layer (100-200 cm), and a relatively stable layer (200-500 cm). PLSR models simulated SMC accurately in diverse soil layers at different scales; almost all values for variation in response (R2) and goodness of prediction (Q2) were >0.5 and >0.0975, respectively. Upper and lower layer SMCs were the two most important factors that influenced diverse soil layers at three scales, and these SMC variables exhibited the highest importance in projection (VIP) values. The 7-day antecedent precipitation and 7-day antecedent potential evapotranspiration contributed significantly to SMC only at the 0-40 cm soil layer. VIP of soil properties, especially sand and silt content, which influenced SMC strongly, increased significantly after increasing the measured scale. Mean annual precipitation and potential evapotranspiration also influenced SMC at the regional scale significantly. Overall, this study indicated that dominant controls of SMC varied among three spatial scales on the Loess Plateau, and VIP was a function of spatial scale and soil depth.

[Nitrogen mineralization rate in different soil layers and its influence factors under plastic film mulched in Danjiangkou Reservoir area, China].

PubMed

Yu, Xing Xiu; Xui, Miao Miao; Zhao, Jin Hui; Zhang, Jia Peng; Wang, Wei; Guo, Ya Li; Xiao, Juan Hua

2018-04-01

The objective of this study was to investigate the rate of nitrogen mineralization in various soil layers (0-10, 10-20, and 20-30 cm) and its influencing factors under plastic film mulching ridge-furrow in a corn field of Wulongchi small watershed, Danjiangkou Reservoir Area. Results showed that the rate of soil ammonification decreased with soil depth during the entire maize growth period. The rate of nitrification in seedling, jointing, and heading stages decreased in the following order: 10-20 cm > 0-10 cm > 20-30 cm, while it increased with soil depth in maturation stage. The rate of soil nitrogen mineralization decreased with the increases in soil depth in the seedling, jointing and heading stages, whereas an opposite pattern was observed in maturation stage. Compared with non-filming, film mulching promoted the soil ammonification process in 0-10 cm and the soil nitrification and nitrogen mineralization processes in jointing, heading, and maturation stages in both 0-10 and 10-20 cm. However, the rates of soil nitrification and nitrogen mineralization under film mulching were much lower than those under non-filming in seedling stage. The stepwise regression analysis indicated that the main factors influencing soil nitrogen mineralization rate varied with soil depth. Soil moisture and total N content were the dominant controller for variation of soil nitrogen mineralization in 0-10 cm layer. Soil temperature, moisture, and total N content were dominant controller for that in 10-20 cm layer. Soil temperature drove the variation of soil nitrogen mineralization in 20-30 cm layer.

Stimulation of 3,4-dichloroaniline mineralization by aniline.

PubMed Central

You, I S; Bartha, R

1982-01-01

Mineralization of free and of humus-bound 3,4-dichloroaniline (DCA) by a Pseudomonas putida strain isolated by analog enrichment was greatly enhanced in the presence of aniline. The addition of aniline to soil that contained 0.2 to 100 micrograms of DCA per g in free or in humus-bound form increased the mineralization rates of DCA severalfold. Within the concentration ranges tested, absolute mineralization of DCA per unit time was positively correlated with both increasing DCA and increasing aniline concentrations. The specific enrichment of microbial populations and the induction of pathways that can co-metabolize DCA are the most plausible explanations for the effect of aniline. The observed phenomenon points to a potential approach for eliminating xenobiotic pollutants from contaminated soils. PMID:7138005

[SANITARY SIGNIFICANCE OF SOIL SEA COASTS].

PubMed

Sidorenko, M L; Buzoleva, L S

2015-01-01

There was investigated the dynamics of growth of Listeria monocytogenes and Yersinia pseudotuberculosis in soils of sea coast (mid-flight and maritime soils). These bacteria were shown to reproduced well in all researched soils, preferring nevertheless maritime soils. The content of the humus was determined to be the one of the limiting factors restricting the multiplication of pathogenic bacteria in studied soils. Abiotic characteristic of soils of sea coast were established to render the direct positive influence on the preservation and reproduction of pathogenic microflora in them. This is promoted by a degree of a saturation by the bases, cation-exchange capacity, quantity of humus. In the formation of environmental policy it should be taken into account and the human-induced load on the soil should be limited

Specific Features of Profile Distribution and Crystallochemistry of Phyllosilicates in Soils of the Cisbaikal Forest-Steppe

NASA Astrophysics Data System (ADS)

Chizhikova, N. P.; Gamzikov, G. P.; Chechetko, E. S.

2018-01-01

The mineralogical composition of agrogray, dark gray, and agro-dark gray soils (Luvic Greyzemic Retic Phaeozems); agro-dark gray residual-calcareous soils (Calcaric Cambic Phaeozems); clay-illuvial agrochernozems (Luvic Chernic Phaeozems); and agrochernozems with migrational-mycelial carbonates (Haplic Chernozems) developed in the forest-steppe of Central Siberia within the Irkutsk Depression has been studied. The clay (<1 μm) fraction separated from these soils consists of mixed-layer minerals with alternating layers of hydromica, smectite, vermiculite, and chlorite; the proportions between them change within the soil profiles. The clay fraction also contains hydromicas, kaolinite, chlorite, and some admixture of the fine-dispersed quartz. Each type of the soils is characterized by its own distribution pattern of clay material with specific alternation of layers in the mixed-layer formations. Mixed-layer minerals of the chlorite-vermiculite type predominate in the upper horizons of texture-differentiated soils. Down the soil profile, the content of mixed-layer mica-smectitic minerals increases. In the clay fraction of arable dark gray-humus soils with residual carbonates, the distribution of the clay fraction and major mineral phases in the soil profile is relatively even. An increased content of well-crystallized kaolinite is typical of these soils. The parent material of agrochernozems has a layered character: the upper horizons are generally depleted of clay, and the middle-profile and lower horizons are characterized by the considerable kaolinite content. In general, the clay material of soils of the Tulun-Irkutsk forest-steppe differs considerably from the clay material of foreststeppe soils developed from loesslike and mantle loams in the European part of Russia. In particular, this difference is seen in the proportions between major mineral phases and between biotitic and muscovitic components, as well as in the degree of crystallinity and behavior of kaolinite and chlorite.

[Effect of elevated atmospheric CO2 on soil urease and phosphatase activities].

PubMed

Chen, Lijun; Wu, Zhijie; Huang, Guohong; Zhou, Likai

2002-10-01

The response of soil urease and phosphatase activities at different rice growth stages to free air CO2 enrichment (FACE) was studied. The results showed that comparing with the ambient atmospheric CO2 concentration (370 mumol.mol-1), FACE (570 mumol.mol-1) significantly increased the urease activity of 0-5 cm soil layer at the vigorous growth stage of rice, whole that of 5-10 cm layer had no significant change during the whole growing season. Phosphatase activity of 0-5 cm and 5-10 cm soil layers significantly increased, and the peak increment was at the vigorous growth stage of rice.

Synthesis and Characterization of Self-Standing and Highly Flexible δ-MnO2@CNTs/CNTs Composite Films for Direct Use of Supercapacitor Electrodes.

PubMed

Wu, Peng; Cheng, Shuang; Yang, Lufeng; Lin, Zhiqiang; Gui, Xuchun; Ou, Xing; Zhou, Jun; Yao, Minghai; Wang, Mengkun; Zhu, Yuanyuan; Liu, Meilin

2016-09-14

Self-standing and flexible films worked as pseudocapacitor electrodes have been fabricated via a simple vacuum-filtration procedure to stack δ-MnO2@carbon nanotubes (CNTs) composite layer and pure CNT layer one by one with CNT layers ended. The lightweight CNTs layers served as both current collector and supporter, while the MnO2@CNTs composite layers with birnessite-type MnO2 worked as active layer and made the main contribution to the capacitance. At a low discharge current of 0.2 A g(-1), the layered films displayed a high areal capacitance of 0.293 F cm(-2) with a mass of 1.97 mg cm(-2) (specific capacitance of 149 F g(-1)) and thickness of only 16.5 μm, and hence an volumetric capacitance of about 177.5 F cm(-3). Moreover, the films also exhibited a good rate capability (only about 15% fading for the capacitance when the discharge current increased to 5 A g(-1) from 0.2 A g(-1)), outstanding cycling stability (about 90% of the initial capacitance was remained after 5,000 cycles) and high flexibility (almost no performance change when bended to different angles). In addition, the capacitance of the films increased proportionally with the stacked layers and the geometry area. E.g., when the stacked layers were three times many with a mass of 6.18 mg cm(-2), the areal capacitance of the films was increased to 0.764 F cm(-2) at 0.5 A g(-1), indicating a high electronic conductivity. It is not overstated to say that the flexible and lightweight layered films emerged high potential for future practical applications as supercapacitor electrodes.

Photoluminescence of phosphorus atomic layer doped Ge grown on Si

NASA Astrophysics Data System (ADS)

Yamamoto, Yuji; Nien, Li-Wei; Capellini, Giovanni; Virgilio, Michele; Costina, Ioan; Schubert, Markus Andreas; Seifert, Winfried; Srinivasan, Ashwyn; Loo, Roger; Scappucci, Giordano; Sabbagh, Diego; Hesse, Anne; Murota, Junichi; Schroeder, Thomas; Tillack, Bernd

2017-10-01

Improvement of the photoluminescence (PL) of Phosphorus (P) doped Ge by P atomic layer doping (ALD) is investigated. Fifty P delta layers of 8 × 1013 cm-2 separated by 4 nm Ge spacer are selectively deposited at 300 °C on a 700 nm thick P-doped Ge buffer layer of 1.4 × 1019 cm-3 on SiO2 structured Si (100) substrate. A high P concentration region of 1.6 × 1020 cm-3 with abrupt P delta profiles is formed by the P-ALD process. Compared to the P-doped Ge buffer layer, a reduced PL intensity is observed, which might be caused by a higher density of point defects in the P delta doped Ge layer. The peak position is shifted by ˜0.1 eV towards lower energy, indicating an increased active carrier concentration in the P-delta doped Ge layer. By introducing annealing at 400 °C to 500 °C after each Ge spacer deposition, P desorption and diffusion is observed resulting in relatively uniform P profiles of ˜2 × 1019 cm-3. Increased PL intensity and red shift of the PL peak are observed due to improved crystallinity and higher active P concentration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thi, Trinh Cham, E-mail: s1240009@jaist.ac.jp; Koyama, Koichi; Ohdaira, Keisuke

We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiN{sub x}) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH{sub 3} molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiN{sub x}/P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiN{sub x} passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRVmore » is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiN{sub x} films. The outstanding results obtained imply that SiN{sub x}/P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells.« less

High mobility, dual layer, c-axis aligned crystalline/amorphous IGZO thin film transistor

NASA Astrophysics Data System (ADS)

Chung, Chen-Yang; Zhu, Bin; Greene, Raymond G.; Thompson, Michael O.; Ast, Dieter G.

2015-11-01

We demonstrate a dual layer IGZO thin film transistor (TFT) consisting of a 310 °C deposited c-axis aligned crystal (CAAC) 20 nm thick channel layer capped by a second, 30 nm thick, 260 °C deposited amorphous IGZO layer. The TFT exhibits a saturation field-effect mobility of ˜20 cm2/V s, exceeding the mobility of 50 nm thick single layer reference TFTs fabricated with either material. The deposition temperature of the second layer influences the mobility of the underlying transport layer. When the cap layer is deposited at room temperature (RT), the mobility in the 310 °C deposited CAAC layer is initially low (6.7 cm2/V s), but rises continuously with time over 58 days to 20.5 cm2/V s, i.e., to the same value as when the second layer is deposited at 260 °C. This observation indicates that the two layers equilibrate at RT with a time constant on the order of 5 × 106 s. An analysis based on diffusive transport indicates that the room temperature diffusivity must be of the order of 1 × 10-18 cm2 s-1 with an activation enthalpy EA < 0.2 eV for the mobility limiting species. The findings are consistent with a hypothesis that the amorphous layer deposited on top of the CAAC has a higher solubility for impurities and/or structural defects than the underlying nanocrystalline transport layer, and that the equilibration of the mobility limiting species is rate limited by hydrogen diffusion, whose known diffusivity fits these estimates.

Experimental research on recolonisation with Anemone nemorosa of the beech forests of the Ruhr district (Germany) floristically impoverished by air pollution.

PubMed

Wittig, Rüdiger

2008-09-01

High SO(2) concentrations as have been observed over decades in the Ruhr district lead to a remarkable reduction of leaf area in the majority of the characteristic broad-leafed herbs of the Central European beech forests even after only a few months of experimental fumigation. Thus, it is no wonder in the time of high SO(2) pollution, e.g., in the town of Herne (centre of the Ruhr district), that there was not a single beech forest hosting, for instance, Viola reichenbachiana or Anemone nemorosa. As air quality has improved very much over some decades in the Ruhr district, one can expect a recolonisation of the beech forests by the species of former time characteristic for the herb layer. However, one has to consider that only the air pollution was reduced, while soil acidification and contamination with heavy metals and PAH are, on the short run, irreversible. That is why experiments were carried out, considering the question as to whether recolonisation of the forests of the Ruhr district by the aforementioned species is possible and why such a recolonisation up to now has not occurred. The experiments were carried out in a beech forest situated in the centre of the Ruhr district in the City of Herne. The wood anemone (A. nemorosa) was chosen as test plant because of its high frequency in beech forests on loess soils outside the Ruhr district, and its absence in beech forests in the Ruhr district. The experiments with A. nemorosa were carried out in three variants with different soils: (a): soil of the local forests (R); (b): soil of the local forests whose soot layer was removed (r); (c): imported soil from a clean air region far away from the Ruhr district (Odenwald). Survival of rhizomes of A. nemorosa is possible for some years in the soils of the Ruhr district; however, the establishment of a population could not be achieved. The results obtained by the imported soil show that it is no longer air pollution, but the soil which prevents the establishment of a population. Sexual reproduction is rather impossible because of the thick litter layer with which all of the Ruhr district's beech forests are covered. With respect to the unfavourable chemistry of the soil of the Ruhr district and in consideration of the unfavourable attributes of the soot layer, the author expected the following order of the development of shoot numbers: O > r > R. However, the result is: O > R > r. In contrast to the expected result, the soot layer has no negative but slightly positive effects on the implanted rhizomes. A possible explanation is that the soot layer, which is situated immediately below the top soil, prevents the top soil from drying up and thus even protects the rhizomes from desiccation. Also, the possibility has to be considered that the soot layer functions as a nutrient storage area. At present, a survival of the rhizomes of A. nemorosa in the soils of the Ruhr district is temporarily possible but does not lead to the establishment of a permanent population. This only can be achieved by additional sexual reproduction. However, the thick litter layer present in all beech forests of the Ruhr district prevents the establishment of seedlings, i.e., it does not allow sexual reproduction to contribute to the population. The soot layer situated below the litter layer represents a second hindrance for germination. Other than seedlings, rhizomes are not negatively affected by the soot layer but even a slight stabilisation has to be stated. As a reason for this slightly positive effect, a protection of the upper mineral soil from desiccation by the hydrophob soot layer has to be considered. Secondly, the soot layer may serve as a nutrient storage which is of particular importance in acid soils, because acidification generally leads to a leeching of nutrients. To answer these questions, detailed further research is necessary. In order to restore the formerly rich herbaceous layer of the forests of the Ruhr district, experiments (removal of the litter layer; liming; ploughing) should be carried out at broad-scale to solve the question of how the strong negative effects of the established thick raw humus layer can be reduced or even be avoided. When the problem of the humus layer is solved, the beech forests of the Ruhr district today highly impoverished in species will become a vivid ecosystem, rich in flowering herbaceous species and thus much more attractive for the people of the Ruhr district than at present.

Influence of altitude concerning the contamination of humus soils in the German Alps: a data evaluation approach using PyHasse.

PubMed

Voigt, Kristina; Brüggemann, Rainer; Kirchner, Manfred; Schramm, Karl-Werner

2010-02-01

In an international project named MONARPOP (Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants), selected chemicals in different environmental media were analysed in the years 2004 and 2005. Seventeen pesticides were chosen and analysed in humus and mineral soil in the German Alps. The samples were taken at different altitudes. In such a rather complex environmental datasets, it is often necessary to compare different sets of criteria and their influence on rankings. In the similarity analysis which is part of the theory of the Hasse diagram technique, we intend to calculate the similarity of different rankings. Furthermore, we perform a so-called dominance-dominance/dominance-separability method, followed by a sensitivity analysis, both subroutines in the newly developed PyHasse programme in order to find out if the concentration of the chemicals can be related to the altitudes at which the samples were taken. It can be demonstrated that the altitude has a considerable influence on the concentration of some organic chemicals in humus: The concentrations of some chemicals increase with the altitude. This increase shows certain irregularities for which several explication attempts including possible effects of atmospheric stratification phenomena in valleys have been made. These results should be complemented in further studies with MONARPOP monitoring data from other Alpine countries, e.g. Austria, Switzerland, Italy and Slovenia.

Metabolism of benzene, toluene, and xylene hydrocarbons in soil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsao, C.W.; Song, H.G.; Bartha, R.

Enrichment cultures obtained from soil exposed to benzene, toluene, and xylene (BTX) mineralized benzene and toluene but cometabolized only xylene isomers, forming polymeric residues. This observation prompted the authors to investigate the metabolism of {sup 14}C-labeled BTX hydrocarbons in soil, either individually or as mixtures. BTX-supplemented soil was incubated aerobically for up to 4 weeks in a sealed system that automatically replenished any O{sub 2} consumed. The decrease in solvent vapors and the production of {sup 14}CO{sub 2} were monitored. At the conclusion of each experiment, {sup 14}C distribution in solvent-extractable polymers, biomass, and humic material was determined, obtaining {supmore » 14}C mass balances of 85 to 98%. BTX compounds were extensively mineralized in soil, regardless of whether they were presented singly or in combinations. No evidence was obtained for the formation of solvent-extractable polymers from xylenes in soil, but {sup 14}C distribution in biomass and humus was unusual for all BTX compounds and especially for toluene and the xylenes. The results suggest that catechol intermediates of BTX degradation are preferentially polymerized into the soil humus and that the methyl substituents of the catechols derived from toluene and especially from xylenes enhance this incorporation. In contrast to inhibitory residues formed from xylene cometabolism in culture, the humus-incorporated xylene residues showed no significant toxicity in the Microtox assay.« less

Wood and humus decay strategies by white-rot basidiomycetes correlate with two different dye decolorization and enzyme secretion patterns on agar plates.

PubMed

Barrasa, José M; Blanco, María N; Esteve-Raventós, Fernando; Altés, Alberto; Checa, Julia; Martínez, Angel T; Ruiz-Dueñas, Francisco J

2014-11-01

During several forays for ligninolytic fungi in different Spanish native forests, 35 white-rot basidiomycetes growing on dead wood (16 species from 12 genera) and leaf litter (19 species from 10 genera) were selected for their ability to decolorize two recalcitrant aromatic dyes (Reactive Blue 38 and Reactive Black 5) added to malt extract agar medium. In this study, two dye decolorization patterns were observed and correlated with two ecophysiological groups (wood and humus white-rot basidiomycetes) and three taxonomical groups (orders Polyporales, Hymenochaetales and Agaricales). Depending on the above groups, different decolorization zones were observed on the dye-containing plates, being restricted to the colony area or extending to the surrounding medium, which suggested two different decay strategies. These two strategies were related to the ability to secrete peroxidases and laccases inside (white-rot wood Polyporales, Hymenochaetales and Agaricales) and outside (white-rot humus Agaricales) of the fungal colony, as revealed by enzymatic tests performed directly on the agar plates. Similar oxidoreductases production patterns were observed when fungi were grown in the absence of dyes, although the set of enzyme released was different. All these results suggest that the decolorization patterns observed could be related with the existence of two decay strategies developed by white-rot basidiomycetes adapted to wood and leaf litter decay in the field. Published by Elsevier Inc.

Sorption kinetics and leachability of heavy metal from the contaminated soil amended with immobilizing agent (humus soil and hydroxyapatite).

PubMed

Chaturvedi, Pranav Kumar; Seth, Chandra Shekhar; Misra, Virendra

2006-08-01

Release of heavy metals onto the soil as a result of agricultural and industrial activities may pose a serious threat to the environment. This study investigated the kinetics of sorption of heavy metals on the non-humus soil amended with (1:3) humus soil and 1% hydroxyapatite used for in situ immobilization and leachability of heavy metals from these soils. For this, a batch equilibrium experiment was performed to evaluate metal sorption in the presence of 0.05 M KNO(3) background electrolyte solutions. The Langmuir isotherms applied for sorption studies showed that the amount of metal sorbed on the amended soil decreased in the order of Pb(2+)>Zn(2+)>Cd(2+). The data suggested the possibility of immobilization of Pb due to sorption process and immobilization of Zn and Cd by other processes like co-precipitation and ion exchange. The sorption kinetics data showed the pseudo-second-order reaction kinetics rather than pseudo-first-order kinetics. Leachability study was performed at various pHs (ranging from 3 to 10). Leachability rate was slowest for the Pb(2+) followed by Zn(2+) and Cd(2+). Out of the metal adsorbed on the soil only 6.1-21.6% of Pb, 7.3-39% of Zn and 9.3-44.3% of Cd leached out from the amended soil.

Mobilities and leachabilities of heavy metals in sludge with humus soil.

PubMed

Zhu, Rui; Wu, Min; Yang, Jian

2011-01-01

Chemical forms of Zn, Ni, Cu, and Pb in municipal sewage sludge were investigated by adding humus soil to sludge and by performing sequential extraction procedures. In the final sludge mixtures, Zn and Ni were mainly found in Fe/Mn oxide-bound (F3) and organic matter/sulfide-bound (F4) forms. For Zn, exchangeable (F1), carbonate-bound (F2), and F3 forms were transformed to F4 and residual forms (F5). For Ni, F1 and F2 forms were transformed to F1, F2, and F3 forms. Both Cu and Pb were strongly associated with the stable forms F4 and F5. For Cu, F2 and F3 forms were major contributors, while for Pb, F3 and F4 forms were major contributors to F5. Humus soil dosage and pH conditions in the sludge were strongly correlated with the forms of heavy metals. Five forms were used to evaluate metal mobilities in the initial and final sludge mixtures. The mobilities of the four heavy metals studied decreased after 28 days. The metal mobilities in the final sludge mixtures were ranked in the following order: Ni > Zn > Cu = Pb. Leaching tests showed that the mobilities of Zn and Ni in lower pH conditions (pH 4) were higher than those in higher pH conditions (pH 8).

Microenvironmental heterogeneity of gut compartments drives bacterial community structure in wood- and humus-feeding higher termites.

PubMed

Mikaelyan, Aram; Meuser, Katja; Brune, Andreas

2017-01-01

Symbiotic digestion of lignocellulose in higher termites (family Termitidae) is accomplished by an exclusively prokaryotic gut microbiota. By deep sequencing of amplified 16S rRNA genes, we had identified diet as the primary determinant of bacterial community structure in a broad selection of termites specialized on lignocellulose in different stages of humification. Here, we increased the resolution of our approach to account for the pronounced heterogeneity in microenvironmental conditions and microbial activities in the major hindgut compartments. The community structure of consecutive gut compartments in each species strongly differed, but that of homologous compartments clearly converged, even among unrelated termites. While the alkaline P1 compartments of all termites investigated contained specific lineages of Clostridiales, the posterior hindgut compartments (P3, P4) differed between feeding groups and were predominantly colonized by putatively fiber-associated lineages of Spirochaetes, Fibrobacteres and the TG3 phylum (wood and grass feeders) or diverse assemblages of Clostridiales and Bacteroidetes (humus and soil feeders). The results underscore that bacterial community structure in termite guts is driven by microenvironmental factors, such as pH, available substrates and gradients of O 2 and H 2 , and inspire investigations on the functional roles of specific bacterial taxa in lignocellulose and humus digestion. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Responses of soil organic carbon and its labile fractions to nitrogen and phosphorus additions in Cunninghamia lanceolata plantations in subtropical China.

PubMed

Zhang, Xiu Lan; Wang, Fang Chao; Fang, Xiang Min; He, Ping; Zhang, Yu Fei; Chen, Fu Sheng; Wang, Hui Min

2017-02-01

A series of nitrogen (N) and phosphorus (P) addition experiments using treatments of N 0 (0 kg N·hm -2 ·a -1 ), N 1 (50 kg N·hm -2 ·a -1 ), N 2 (100 kg N·hm -2 ·a -1 ), P (50 kg P·hm -2 ·a -1 ), N 1 P and N 2 P were conducted at Cunninghamia lanceolata plantations in subtropical China. The responses of soil organic carbon (SOC), particulate organic carbon (POC) and water-soluble organic carbon (WSOC) to the nutrient addition treatments after 3 years were determined. The results showed that N and P additions had no significant effects on SOC concentration in 0-20 cm soil layer, while P addition significantly decreased soil POC content in 0-5 cm soil layer by 26.1%. The responses of WSOC to N and P addition were mainly found in 0-5 cm soil layer, and low level N and P addition significantly increased the WSOC content in 0-5 cm soil layer. Nitrogen addition had no significant effect on POC/SOC, while the POC/SOC significantly decreased by 15.9% in response to P addition in 0-5 cm soil layer. In 5-10 cm and 10-20 cm soil layers, POC/SOC was not significantly altered in N and P addition treatments. Therefore, the forest soil C stability was mainly controlled by P content in subtropical areas. P addition was liable to cause the decomposition of surface soil active organic C and increased the soil C stability in the short term treatment.

Performance Analysis of GaN Capping Layer Thickness on GaN/AlGaN/GaN High Electron Mobility Transistors.

PubMed

Sharma, N; Periasamy, C; Chaturvedi, N

2018-07-01

In this paper, we present an investigation of the impact of GaN capping layer and AlGaN layer thickness on the two-dimensional (2D)-electron mobility and the carrier concentration which was formed close to the AlGaN/GaN buffer layer for Al0.25Ga0.75N/GaN and GaN/Al0.25Ga0.75N/GaN heterostructures deposited on sapphire substrates. The results of our analysis clearly indicate that expanding the GaN capping layer thickness from 1 nm to 100 nm prompts an increment in the electron concentration at hetero interface. As consequence of which drain current was additionally increments with GaN cap layer thicknesses, and eventually saturates at approximately 1.85 A/mm for capping layer thickness greater than 40 nm. Interestingly, for the same structure, the 2D-electron mobility, decrease monotonically with GaN capping layer thickness, and saturate at approximately 830 cm2/Vs for capping layer thickness greater than 50 nm. A device with a GaN cap layer didn't exhibit gate leakage current. Furthermore, it was observed that the carrier concentration was first decrease 1.03 × 1019/cm3 to 6.65 × 1018/cm3 with AlGaN Layer thickness from 5 to 10 nm and after that it increases with the AlGaN layer thickness from 10 to 30 nm. The same trend was followed for electric field distributions. Electron mobility decreases monotonically with AlGaN layer thickness. Highest electron mobility 1354 cm2/Vs were recorded for the AlGaN layer thickness of 5 nm. Results obtained are in good agreement with published experimental data.

The Effect of RDX Crystal Defect Structure on Mechanical Response of a Polymer-Bonded Explosive

DTIC Science & Technology

2015-11-09

standard geometry. From left to right there is a 5 cm steel cylinder filled with sand, a 10 cm steel cylinder filled with the PBX, and a 5 cm steel tube...third of the circumference of the cylinder was used to drive the deformation of the steel -encased Table 1. Identification of PBX, source of RDX Class I...thickness of the Semtex 10 plastic explosive layer was varied. A 4 mm thick rubber foam layer was put in be- tween the Semtex 10 layer and the steel

Biogeochemistry of Decomposition and Detrital Processing

NASA Astrophysics Data System (ADS)

Sanderman, J.; Amundson, R.

2003-12-01

Decomposition is a key ecological process that roughly balances net primary production in terrestrial ecosystems and is an essential process in resupplying nutrients to the plant community. Decomposition consists of three concurrent processes: communition or fragmentation, leaching of water-soluble compounds, and microbial catabolism. Decomposition can also be viewed as a sequential process, what Eijsackers and Zehnder (1990) compare to a Russian matriochka doll. Soil macrofauna fragment and partially solubilize plant residues, facilitating establishment of a community of decomposer microorganisms. This decomposer community will gradually shift as the most easily degraded plant compounds are utilized and the more recalcitrant materials begin to accumulate. Given enough time and the proper environmental conditions, most naturally occurring compounds can completely be mineralized to inorganic forms. Simultaneously with mineralization, the process of humification acts to transform a fraction of the plant residues into stable soil organic matter (SOM) or humus. For reference, Schlesinger (1990) estimated that only ˜0.7% of detritus eventually becomes stabilized into humus.Decomposition plays a key role in the cycling of most plant macro- and micronutrients and in the formation of humus. Figure 1 places the roles of detrital processing and mineralization within the context of the biogeochemical cycling of essential plant nutrients. Chapin (1991) found that while the atmosphere supplied 4% and mineral weathering supplied no nitrogen and <1% of phosphorus, internal nutrient recycling is the source for >95% of all the nitrogen and phosphorus uptake by tundra species in Barrow, Alaska. In a cool temperate forest, nutrient recycling accounted for 93%, 89%, 88%, and 65% of total sources for nitrogen, phosphorus, potassium, and calcium, respectively ( Chapin, 1991). (13K)Figure 1. A decomposition-centric biogeochemical model of nutrient cycling. Although there is significant external input (1) and output (2) from neighboring ecosystems (such as erosion), weathering of primary minerals (3), loss of secondary minerals (4), atmospheric deposition and N-fixation (5) and volatilization (6), the majority of plant-available nutrients are supplied by internal recycling through decomposition. Nutrients that are taken up by plants (7) are either consumed by fauna (8) and returned to the soil through defecation and mortality (10) or returned to the soil through litterfall and mortality (9). Detritus and humus can be immobilized into microbial biomass (11 and 13). Humus is formed by the transformation and stabilization of detrital (12) and microbial (14) compounds. During these transformations, SOM is being continually mineralized by the microorganisms (15) replenishing the inorganic nutrient pool (after Swift et al., 1979). The second major ecosystem role of decomposition is in the formation and stabilization of humus. The cycling and stabilization of SOM in the litter-soil system is presented in a conceptual model in Figure 2. Parallel with litterfall and most root turnover, detrital processing is concentrated at or near the soil surface. As labile SOM is preferentially degraded, there is a progressive shift from labile to passive SOM with increasing depth. There are three basic mechanisms for SOM accumulation in the mineral soil: bioturbation or physical mixing of the soil by burrowing animals (e.g., earthworms, gophers, etc.), in situ decomposition of roots and root exudates, and the leaching of soluble organic compounds. In the absence of bioturbation, distinct litter layers often accumulate above the mineral soil. In grasslands where the majority of net primary productivity (NPP) is allocated belowground, root inputs will dominate. In sandy soils with ample rainfall, leaching may be the major process incorporating carbon into the soil. (11K)Figure 2. Conceptual model of carbon cycling in the litter-soil system. In each horizon or depth increment, SOM is represented by three pools: labile SOM, slow SOM, and passive SOM. Inputs include aboveground litterfall and belowground root turnover and exudates, which will be distributed among the pools based on the biochemical nature of the material. Outputs from each pool include mineralization to CO2 (dashed lines), humification (labile→slow→passive), and downward transport due to leaching and physical mixing. Communition by soil fauna will accelerate the decomposition process and reveal previously inaccessible materials. Soil mixing and other disturbances can also make physically protected passive SOM available to microbial attack (passive→slow). There exists an amazing body of literature on the subject of decomposition that draws from many disciplines - including ecology, soil science, microbiology, plant physiology, biochemistry, and zoology. In this chapter, we have attempted to draw information from all of these fields to present an integrated analysis of decomposition in a biogeochemical context. We begin by reviewing the composition of detrital resources and SOM (Section 8.07.2), the organisms responsible for decomposition ( Section 8.07.3), and some methods for quantifying decomposition rates ( Section 8.07.4). This is followed by a discussion of the mechanisms behind decomposition ( Section 8.07.5), humification ( Section 8.07.6), and the controls on these processes ( Section 8.07.7). We conclude the chapter with a brief discussion on how current biogeochemical models incorporate this information ( Section 8.07.8).

[Fine root biomass and production of four vegetation types in Loess Plateau, China].

PubMed

Deng, Qiang; Li, Ting; Yuan, Zhi-You; Jiao, Feng

2014-11-01

Fine roots (≤ 2 mm) play a major role in biogeochemical cycling in ecosystems. By the methods of soil cores and ingrowth soil cores, we studied the biomass and annual production of fine roots in 0-40 cm soil layers of four main vegetation types, i. e. , Robinia pseudoacacia plantation, deciduous shrubs, abandoned grassland, and Artemisia desertorum community in Loess Plateau, China. The spatial patterns of fine root biomass and production were negatively associated with latitudes. The fine root biomass in the 0-40 cm soil layer was in the order of deciduous shrubs (220 g · m(-2)), R. pseudoacacia plantation (163 g · m(-2)), abandoned grassland (162 g · m(-2)) and A. desertorum community (79 g · m(-2)). The proportion of ≤ 1 mm fine root biomass (74.1%) in the 0-40 cm soil layer of abandoned grassland was significantly higher than those in the other three vegetation types. The fine root biomass of the four vegetation types was mainly distributed in the 0-10 cm soil layer and decreased with soil depth. The proportion of fine root biomass (44.1%) in the 0-10 cm soil layer of abandoned grassland was significantly higher than those in other three vegetation types. The fine root productions of four vegetation types were in the order of abandoned grassland (315 g · m(-2) · a(-1)) > deciduous shrubs (249 g · m(-2) a(-1)) > R. pseudoacacia plantation (219 g · m(-2) · a(-1)) > A. desertorum community (115 g · m(-2) · a(-1)), and mainly concentrated in the 0-10 cm top soil layer and decreased with the soil depth. The proportion of the annual production (40.4%) in the 0-10 cm soil layer was the highest in abandoned grassland. Fine roots of abandoned grassland turned over faster than those from the other three vegetation types.

Heavy Metals Technogenic Pollution of Plough Lands Arable Layer in the Chelyabinsk Region

NASA Astrophysics Data System (ADS)

Mantorova, G. F.

2017-11-01

Environmental protection and rational use of natural resources in agriculture are the main directions of this scientific research. Contamination is caused by the substances of chemical, radiation and biological origin above the maximum permissible concentration (MPC). The main source of soil contamination in the arable land, hayfields and pastures is the waste of livestock complexes, agricultural chemicals (fertilizers, pesticides), motor vehicle exhausts, industrial emissions, sewage from settlements, etc. The ecological state of the soil and vegetation cover is largely determined by agricultural activities. The agricultural production technology complicating is accompanied by increase in the degree of environmental risk, especially in the chemicalization of agriculture. Pollution also enters the soil with atmospheric precipitation, surface waste. They are also introduced into the soil layer by soil and groundwater. The most dangerous for human health is considered to be contamination with heavy metals (HM)-lead, mercury and cadmium. However, the concentration of the rest elements is no less harmful. The paradox of heavy metals is that in certain quantities they are necessary to ensure the normal life of plants and organisms but their excess can lead to serious diseases and even death. A nutritional cycle causes harmful compounds to enter the human body and often cause great harm to health. The present work reveals the results of the research of a long-term experience on accumulation and distribution of heavy metals on the arable layer profile depending on the concentration in humus soil and the system of ground processing.

Designing of the 14 MeV neutron moderator for BNCT

NASA Astrophysics Data System (ADS)

Cheng, Dao-Wen; Lu, Jing-Bin; Yang, Dong; Liu, Yu-Min; Wang, Hui-Dong; Ma, Ke-Yan

2012-09-01

In boron neutron capture therapy (BNCT), the ratio of the fast neutron flux to the neutron flux in the tumor (RFNT) must be less than 3%. If a D-T neutron generator is used in BNCT, the 14 MeV neutron moderator must be optimized to reduce the RFNT. Based on the neutron moderation theory and the simulation results, tungsten, lead and diamond were used to moderate the 14 MeV neutrons. Satisfying RFNT of less than 3%, the maximum neutron flux in the tumor was achieved with a three-layer moderator comprised of a 3 cm thick tungsten layer, a 14 cm thick lead layer and a 21 cm thick diamond layer.

Preparation of 2-in.-diameter (001) β-Ga2O3 homoepitaxial wafers by halide vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Thieu, Quang Tu; Wakimoto, Daiki; Koishikawa, Yuki; Sasaki, Kohei; Goto, Ken; Konishi, Keita; Murakami, Hisashi; Kuramata, Akito; Kumagai, Yoshinao; Yamakoshi, Shigenobu

2017-11-01

The homoepitaxial growth of thick β-Ga2O3 layers on 2-in.-diameter (001) wafers was demonstrated by halide vapor phase epitaxy. Growth rates of 3 to 4 µm/h were confirmed for growing intentionally Si-doped n-type layers. A homoepitaxial layer with an average thickness and carrier concentration of 10.9 µm and 2.7 × 1016 cm-3 showed standard deviations of 1.8 µm (16.5%) and 0.5 × 1016 cm-3 (19.7%), respectively. Ni Schottky barrier diodes fabricated directly on a 5.3-µm-thick homoepitaxial layer with a carrier concentration of 3.4 × 1016 cm-3 showed reasonable reverse and forward characteristics, i.e., breakdown voltages above 200 V and on-resistances of 3.8-7.7 mΩ cm2 at room temperature.

Nondispersive hole transport in a spin-coated dendrimer film measured by the charge-generation-layer time-of-flight method

NASA Astrophysics Data System (ADS)

Markham, Jonathan P. J.; Anthopoulos, Thomas D.; Samuel, Ifor D. W.; Richards, Gary J.; Burn, Paul L.; Im, Chan; Bassler, Heinz

2002-10-01

Measurements of the mobility of a first-generation (G1) bis-fluorene cored dendrimer have been performed on spin-coated samples of 500 nm thickness using the charge-generation-layer time-of-flight (TOF) technique. A 10 nm perylene charge generation layer was excited by the 532 nm line of a Q-switched Nd:YAG laser and the generated carriers swept through the dendrimer film under an applied field. We observe nondispersive hole transport in the dendrimer layer with a room-temperature mobility mu=2.0 x10-4 cm2/V s at a field of 0.55 MV/cm. There is a weak field dependence of the mobility and it increases from mu=1.6 x10-4 cm2/V s at 0.2 MV/cm to mu=3.0 x10-4 cm2/V s at 1.4 MV/cm. These results suggest that the measurement of mobility by TOF in spin-coated samples on thickness scales relevant to organic light-emitting diodes can yield valuable information, and that dendrimers are promising materials for device applications.

Biological soil crust formation under artificial vegetation effect and its properties in the Mugetan sandy land, northeastern Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Li, Y. F.; Li, Z. W.; Jia, Y. H.; Zhang, K.

2016-08-01

Mugetan sandy land is an inland desertification area of about 2,065 km2 in the northeastern Qinghai-Tibet Plateau. In the ecological restoration region of the Mugetan sandy land, different crusts have formed under the action of vegetation in three types of sandy soil (i.e. semi-fixed sand dune, fixed sand dune and ancient fixed aeolian sandy soil). The surface sand particle distribution, mineral component and vegetation composition of moving sand dunes and three types of sandy soil were studied in 2010-2014 to analyze the biological crust formation properties in the Mugetan sandy land and the effects of artificial vegetation. Results from this study revealed that artificial vegetation increases the clay content and encourages the development of biological curst. The fine particles (i.e. clay and humus) of the surface layer of the sand dunes increased more than 15% ten years after the artificial vegetation planting, and further increased up to 20% after one hundred years. The interaction of clay, humus, and other fine particles formed the soil aggregate structure. Meanwhile, under the vegetation effect from the microbes, algae, and moss, the sand particles stuck together and a biological crust formed. The interconnection of the partial crusts caused the sand dunes to gradually be fixed as a whole. Maintaining the integrity of the biological crust plays a vital role in fixing the sand under the crust. The precipitation and temperature conditions in the Mugetan sandy land could satisfy the demand of biological crust formation and development. If rational vegetation measures are adopted in the region with moving sand dunes, the lichen-moss-algae biological curst will form after ten years, but it still takes more time for the sand dunes to reach the nutrient enrichment state. If the biological curst is partly broken due to human activities, reasonable closure and restoration measures can shorten the restoration time of the biological crust.

Soil fertility status and spatial distribution of selected trace elements in south-western Serbia

NASA Astrophysics Data System (ADS)

Mrvic, Vesna; Kostic-Kravljanac, Ljiljana; Cakmak, Dragan; Pivic, Radmila; Saljnikov, Elmira; Nikoloski, Mile; Perovic, Veljko

2010-05-01

Soil fertility status and spatial distribution of selected trace elements in south-western Serbia V. Mrvic, Lj. Kostic-Kravljanac, D. Čakmak, R. Pivić, E. Saljnikov, M. Nikoloski, V. Perović Institute of Soil Science, 11000 Belgrade, Serbia (vesnavmrvic@yahoo.com) Main characteristic of surface soil layer (pH in KCl, humus, available P and K), and content of trace elements (Ni, Cr, Cu, Zn, Pb, Cd, As, Hg) were analysed on area of southwestern Serbia, covering total 959 000 ha (one sample represents 1000 ha) . About 30 % of samples have very acid reaction. Main portion of soil samples (86%) is poorly suplied with available phosphorus (<8 mg/100g), and these are located under forests, meadows, pastures and orchards. Supplies of available potasium and humus are well. On the other hand, in small number of soil samples (4%), mostly on fertile alluvial soils, there are high P and K concentration, which are consequence of inadequate usage of mineral fertilizers. Content of trace elements in 70 % of soil samples is bellow maximum allowed concentration (MAC). The most frequente potential pollutants are Cr and Ni, which is assosiated with mafic and ultramafic rocks, which are common in this region (mountains naerby river Ibar - Troglav, Stolovi, Čemerno, Željin, Golija, Kopaonik; near Sjenica- peridotites of mn. Ozren). There are dominace of Eutric Leptosols soil type, with Ni content above 100 mg/kg, and in some samples above 1000 mg/kg. In smaller number of samples arsenic and lead exceed MAC, while other elements exceed MAD very rarelly. There are elevated Pb content in Kopaonik mountain area, and elevated As content besides this region, are in mine zone of Golija and Cemerno. These are mountain soils formed on acid igneous and metamorphic rocks, which are enriched with ores of Pb, Zn and other elements. Eventually negative influences of these elements on plants and other components of ecosystem may be esstimated only after detalied investigation.

Globally Convergent Methods for Solving Coefficient Inverse Problems for Time Dependent Maxwell Equations

DTIC Science & Technology

2014-08-19

geode (heterogeneous): Rock two spherical layers and air inside 13 Blind A piece of rock Rock 14 Blind A plastic bottle filled with coffee grounds... Coffee grounds 15 Blind A ceramic mug Ceramic 16 Blind A cylinder and a block at 3 cm separation Metal/Metal 17 Blind An aluminum can and a block Metal...2.5 cm 1.0 1.52 1.31 (outer) (two layers) 1.25 (inner) 1.28 (average) 13 Rock 2.0 cm 2.3 cm 1.0 1.34 1.34 14 Coffee grounds 2.0 cm 2.5 cm 1.0 1.46

Prenatal histomorphological development of the rumen in Dama dama.

PubMed

Redondo, Eloy; García, Ángela; Ortega, Cristina; Peña, Fernando J; Masot, A Javier

2018-06-12

This work studies the morphological changes taking place in the Dama dama rumen during prenatal development using histomorphometrics, surface micro-structure and immunohistochemistry analysis as well as carrying out a comparative analysis of this species with other wild (red deer) and domestic-type ruminants. A total of 25 fallow deer embryos and fetuses were used, from the first stage of prenatal life until birth. The appearance of the rumen from the primitive gastric tube was observed at 51 days of prenatal life (CRL 3 cm, 21% gestation). By 57 days (CRL 4.3 cm, 24% gestation) the ruminal wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Ruminal pillars were visible at 72 days (CRL 6 cm, 30% gestation), and by 85 days (CRL 7.2 cm, 35% gestation) ruminal papillae were starting to appear. Under scanning electron microscopy, by 80 days (CRL 7 cm, 33% gestation) small ruminal papillae were observed protruding from the surface. Morphometric results showed accelerated growth of the epithelial layer and the tunica muscularis at 180 days (75% gestation). By contrast, the growth-rate of the lamina propria and submucosa declined from the early embryonic stages until birth. The serosa maintained a steady rate of growth until birth. Neuroendocrine cells (synaptophysin) were detected at 85 days (CRL 7.2 cm CRL, 35% gestation), while glial cell markers (glial fibrillary acidic protein and vimentin) were found at 108 days (CRL 31 cm, 45% gestation) and 63 days (CRL 4.4 cm, 26% gestation) respectively. Neuropeptide Y and vasoactive intestinal polypeptide were detected immunohistochemically at 180 days (CRL 33 cm, 75% gestation) and 192 days (CRL 35 cm, 80% gestation) respectively. In comparison to other wild and domestic-type ruminants, histomorphogenesis of the rumen in Dama dama was similar to that reported in red deer and goats, but rather slower than that observed for sheep or cattle.

Can forest transformation help reducing floods in forested watersheds? Certain aspects on soil hydraulics and organic matter properties

NASA Astrophysics Data System (ADS)

Wahl, N. A.; Wöllecke, B.; Bens, O.; Hüttl, R. F.

Former floodplains in many European countries increasingly suffer from serious floods due to intensified human activity. These floods have caused safety and ecological problems as well as they have resulted in economic losses in agricultural used watersheds. In this context, the influence of the management practice of forest transformation in forested areas on soil hydraulic properties is presented and discussed as a means of preventing such disasters at a reasonable cost and during a foreseeable period. Investigations were carried out in northeastern Germany on forest stands differing in tree populations and stand structure. It was found that infiltration capacity and hydraulic conductivity K exhibit overall low values nevertheless the tree species. This finding appears to be related to water repellency, the predominating texture, and a poor macroporosity. During the different stages of forest transformation, the type and amount of soil organic matter and humus in the litter layer change, leading to a decrease of the water capacity of the litter layer and the uppermost part of the mineral soil. Furthermore, these changes affect soil properties connected with water repellency. It is concluded that for the approximate duration of one century the practice of forest transformation does not contribute to flood prevention through enhanced infiltration capacity or water retention.

Effects of PCB Substrate Surface Finish, Flux, and Phosphorus Content on Ionic Contamination

NASA Astrophysics Data System (ADS)

Bacior, M.; Sobczak, N.; Siewiorek, A.; Kudyba, A.; Homa, M.; Nowak, R.; Dziula, M.; Masłoń, S.

2015-02-01

The ionic contamination on printed circuit boards (PCB) having different surface finishes was examined using ionograph. The study was performed at the RT on three types of PCBs covered with: (i) hot air solder leveling (HASL LF), (ii) electroless nickel immersion gold (ENIG), and (iii) organic surface protectant (OSP), all on Cu substrates, as well as two types of fluxes, namely EF2202 and RF800. In the group of boards without soldered components, the lowest average value of contamination was for the ENIG 18 µm surface (0.01 μg NaCl/cm2). Boards with soldered components were more contaminated (from 0.29 μg NaCl/cm2 for the HASL LF 18 µm surface). After spraying boards with fluxing agents, the values of contaminants were the highest. The influence of phosphorus content in Ni-P layer of ENIG finish on ionic contamination was examined. In the group of PCBs with Au coating, the smallest amount of surface contaminants (0.32 μg NaCl/cm2) was for Ni-2-5%P layer. PCBs with Ni-11%P layer were higher contaminated (0.47 μg NaCl/cm2), and another with Ni-8%P layer had 0.81 μg NaCl/cm2. PCBs without Au coating, had the lowest contamination (0.48 μg NaCl/cm2) at phosphorous content equal 11%P. Higher contamination (0.67 μg NaCl/cm2) was at 2-5%P, up to 1.98 μg NaCl/cm2 for 8% of P. Boards with Au finish have lower value of contamination than identical boards without Au layer thus contributing to better reliability of electronic assemblies, since its failures due to current leakage and corrosion can be caused by contaminants.

Molecular structure of human aortic valve by μSR- FTIR microscopy

NASA Astrophysics Data System (ADS)

Borkowska, Anna M.; Nowakowski, Michał; Lis, Grzegorz J.; Wehbe, Katia; Cinque, Gianfelice; Kwiatek, Wojciech M.

2017-11-01

Aortic valve is a part of the heart most frequently affected by pathological processes in humans what constitute a very serious health problem. Therefore, studies of morphology and molecular microstructure of the AV are needed. μSR- FTIR spectroscopy and microscopy represent unique tools to study chemical composition of the tissue and to identify spectroscopic markers characteristic for structural and functional features. Normal AV reveals a multi-layered structure and the compositional and structural changes within particular layers may trigger degenerative processes within the valve. Thus, deep insight into the structure of the valve to understand pathological processes occurring in AV is needed. In order to identify differences between three layers of human AV, tissue sections of macroscopically normal AV were studied using μSR- FTIR spectroscopy in combination with histological and histochemical stainings. Tissue sections deposited onto CaF2 substrates were mapped and representative set of IR spectra collected from fibrosa, spongiosa and ventricularis were analysed by Principal Component Analysis (PCA) in the spectral range between 1850-1000 cm-1 and 3050-2750 cm-1. PCA revealed a layered molecular structure of the valve and it was possible to identify IR bands associated to different tissue parts. Spongiosa layer was well differentiated from other two layers mainly based on IR bands characteristic for the distribution of glycosaminoglycans (GAGs) in the tissue - like 1170 cm-1 (υas(C-O-S)) and 1380 cm-1 (acetyl amino group). Additionally, it was distinguished from fibrosa and ventricularis based on 1085 cm-1 and 1240 cm-1 bands characteristic for GAGs and for carbohydrates- ν(C-O) and ν(C-O-C) respectively and nucleic acids -νsym(PO2-) and νasym(PO2-) respectively, which were less specific for this layer. The use of μSR- FTIR spectroscopy demonstrated co-localization of GAGs and lipids in spongiosa layer what may indicate their contribution in the very early phase of aortic valve calcific degeneration.

Suppression of Mg propagation into subsequent layers grown by MOCVD

NASA Astrophysics Data System (ADS)

Agarwal, Anchal; Tahhan, Maher; Mates, Tom; Keller, Stacia; Mishra, Umesh

2017-01-01

Low temperature (LT) flow modulation epitaxy (FME) or "pulsed" growth was successfully used to prevent magnesium from Metalorganic Chemical Vapor Deposition (MOCVD) grown p-GaN:Mg layers riding into subsequently deposited n-type layers. Mg concentration in the subsequent layers was lowered from ˜1 × 1018 cm-3 for a medium temperature growth at 950 °C to ˜1 × 1016 cm-3 for a low temperature growth at 700 °C via FME. The slope of the Mg concentration drop in the 700 °C FME sample was 20 nm/dec—the lowest ever demonstrated by MOCVD. For growth on Mg implanted GaN layers, the drop for a medium temperature regrowth at 950 °C was ˜10 nm/dec compared to >120 nm/dec for a high temperature regrowth at 1150 °C. This drop-rate obtained at 950 °C or lower was maintained even when the growth temperature in the following layers was raised to 1150 °C. A controlled silicon doping series using LT FME was also demonstrated with the lowest and highest achieved doping levels being 5 × 1016 cm-3 and 6 × 1019 cm-3, respectively.

Technology of silicon charged-particle detectors developed at the Institute of Electron Technology (ITE)

NASA Astrophysics Data System (ADS)

Wegrzecka, Iwona; Panas, Andrzej; Bar, Jan; Budzyński, Tadeusz; Grabiec, Piotr; Kozłowski, Roman; Sarnecki, Jerzy; Słysz, Wojciech; Szmigiel, Dariusz; Wegrzecki, Maciej; Zaborowski, Michał

2013-07-01

The paper discusses the technology of silicon charged-particle detectors developed at the Institute of Electron Technology (ITE). The developed technology enables the fabrication of both planar and epiplanar p+-ν-n+ detector structures with an active area of up to 50 cm2. The starting material for epiplanar structures are silicon wafers with a high-resistivity n-type epitaxial layer ( ν layer - ρ < 3 kΩcm) deposited on a highly doped n+-type substrate (ρ< 0,02Ωcm) developed and fabricated at the Institute of Electronic Materials Technology. Active layer thickness of the epiplanar detectors (νlayer) may range from 10 μm to 150 μm. Imported silicon with min. 5 kΩcm resistivity is used to fabricate planar detectors. Active layer thickness of the planar detectors (ν) layer) may range from 200 μm to 1 mm. This technology enables the fabrication of both discrete and multi-junction detectors (monolithic detector arrays), such as single-sided strip detectors (epiplanar and planar) and double-sided strip detectors (planar). Examples of process diagrams for fabrication of the epiplanar and planar detectors are presented in the paper, and selected technological processes are discussed.

Soil development in OSL dated sandy dune substrates under Quercus robur Forest (Netherlands)

NASA Astrophysics Data System (ADS)

van Mourik, J. M.; Nierop, Ir. K.; Verstraten, J. M.

2009-04-01

Coastal dune landscapes are very dynamic. The present distribution of vegetation and soil is the result of over 2000 years of natural processes and human management. The initial soil development was controlled by an increase of the organic matter content, which consisted mainly of decomposed roots of grasses (rhizomull), and a decrease of the soil pH to 3-4 by decalcification. This stage was followed by the development of a deciduous forest, which was dominated by Quercus robur. Since 1600 AD, a large part of the deciduous forest that dominated the east side of the coastal dune landscape transferred in expensive residential areas and urbanizations. Nevertheless some parts of the oak forest belt remained. The present forest soils are acid and the controlling soil processes are leaching of sesquioxides and storage of organic matter in mormoder humus forms. The sustainability of ecosystems is closely related to the quality of the humus form, controlling nutrient cycling and water supply. Therefore, improve of knowledge of humus form development and properties is important. We applied soil micromorphology and pyrolysis-gas chromatography/mass spectrometry (GC/MS) to investigate more details of humus form development at two locations (Duivendrift and Hoek van Klaas) in the coastal dune area of the Amsterdamse Waterleidingduinen (near Haarlem, the Netherlands). However, to understand forest soil development, including the organic matter composition in the humus form, the age of the substrate and the forest is required. Therefore, we used tradition techniques as pollen analysis and radiocarbon dating but also the recently introduced optical stimulated luminescence (OSL) dating technique. OSL dating works excellent for aeolian sandy deposits with a high percentage of quartz grains. The OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. Or in other words, the start of a stable period without sand drifting. In the Ah horizons we observed palynological traces of a former dune landscape with grasses and typical dune land shrubs. The F and H horizons were dominated by Quercus pollen. In thin sections we found that in the upper part of the F horizons the soil skeleton was formed by leaf litter fragments that were fragmented and decomposed by fungi and micro arthropods. The soil skeleton of the lower part of the F horizons consisted of a mixture of leaf litter fragments and (dead) root fragments. In this part of the profile, fungi and micro arthropods were also responsible for the physical and chemical organic matter decomposition. The soil skeleton of the Ah horizons was formed by mineral grains in which small sized organic aggregates occurred. These aggregates may have four possible sources: (1) sinsedimentary aggregates, involved in sand drifting, (2) fecal relicts from decomposed (older) roots of a former dune land vegetation, (2) fecal relicts from decomposed (younger) roots of the forest and its understory, and (3) infiltrated parts of fecal pallets from the overlying F horizons. The calibrated radiocarbon dates of organic matter from the upper 5 cm of the Ah horizons go back to around 1960 AD. This points to a 45 year period for the development of the ectorganic horizons, assuming that fresh organic matter did not ‘contaminate' the radiocarbon dating. The OSL the ages of quartz grains from the upper 5 cm of the Ah horizons indicate landscape stabilization around 1800AD implying that two centuries were available for vegetation and soil development. There seems to be a significant difference between the OSL and 14C ages of the top of the Ah horizon. The OSL dates are very reliable. They indicate the correct time of the transformation of drift sand into stable, vegetated landscape. The pollen spectra of the Ah horizon show traces of dune grass and shrub landscape, but probably these pollen grains originate from sinsedimentary organic aggregates. And during the juvenile phase of a quercus forest, the quercus pollen production is very low and other wind pollinated grains from dune grasses and shrubs can dominate the pollen spectra. Based upon OSL dates, a period of 200 year forest soil development is more reliable than the 14C based 45 year. We must reject the 14C ages, due to complexity of sources of soil organic matter in the Ah horizon The organic matter as investigated by analytical pyrolysis and thermally assisted hydrolysis and methylation and subsequent analysis by GC/MS revealed a major oak-derived picture. The L+F1 horizons reflected relatively undecomposed organic matter mainly derived from leaves. By contrast, in both F2+H and the Ah horizons leaf material was accompanied by root-derived components, particularly suberin. The latter may originate from barks as well, but in the Ah horizons the contribution of roots was most probably much greater. Apart from a common transformation pattern (decrease of polysaccharides, degradation of lignin and accumulation of lipids), a very small contribution of C26 alkanol indicated a chemical fingerprint of the previous grass vegetation. In conclusion: chemical analysis confirmed the soil micromorphological data, and the application of OSL dating improves our knowledge about geochronology of the system.

Buffer layers on metal alloy substrates for superconducting tapes

DOEpatents

Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

2004-06-29

An article including a substrate, a layer of an inert oxide material upon the surface of the substrate, a layer of an amorphous oxide or oxynitride material upon the inert oxide material layer, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the amorphous oxide material layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected IC's of over 200 Amperes across a sample 1 cm wide.

Atrazine degradation and enzyme activities in an agricultural soil under two tillage systems.

PubMed

Mahía, Jorge; Martín, Angela; Carballas, Tarsy; Díaz-Raviña, Montserrat

2007-05-25

The content of atrazine and its metabolites (hydroxyatrazine, deethylatrazine and deisopropylatrazine) as well as the activities of two soil enzymes (urease and beta-glucosidase) were evaluated in an acid agricultural soil, located in a temperate humid zone (Galicia, NW Spain), with an annual ryegrass-maize rotation under conventional tillage (CT) and no tillage (NT). Samples were collected during two consecutive years from the arable layer at two depths (0-5 cm and 5-20 cm) and different times after atrazine application. Hydroxyatrazine and deisopropylatrazine were the main metabolites resulting from atrazine degradation in the acid soil studied, the highest levels being detected in the surface layer of the NT treatment. A residual effect of atrazine was observed since hydroxyatrazine was detected in the arable layer (0-5 cm, 5-20 cm) even one year after the herbicide application. Soil enzyme activities in the upper 5 cm layer under NT were consistently higher than those in the same layer under CT. Urease and beta-glucosidase activities decreased with depth in the profile under NT but they did not show any differences between the two depths for the plots under CT. For both tillage systems enzyme activities also reflected temporal changes during the maize cultivation; however, no consistent effect of the herbicide application was observed.

Ion movement in acidified, low base saturated sand soils.

Treesearch

A. Ray Harris; Douglas M. Stone

1992-01-01

Describes factors causing cation export in leachate in low base saturated forested sand soils. Reports the effects of varying acid precipitation and litter-humus treatments on ion movement and interaction.

Heavy metal solubility in podzolic soils exposed to the alkalizing effect of air pollutants.

PubMed

Haapala, H; Goltsova, N; Lodenius, M

2001-01-01

The heavy metal content of pine forest soil was studied near the boundary between Russia and Estonia, an area characterized by large amounts of acidic and basic air pollutants, mainly sulfur dioxide and calcium. Alkalization dominates the processes in soil, since sulfur is adsorbed only in small quantities, and calcium is much better adsorbed. In addition to Ca, great amounts of Al, Fe, K, and Mg are accumulated in the humus layer due to air pollution. The heavy metal content has increased. The exchangeable content of heavy metals was in many cases much higher in polluted alkaline soils than in non-polluted acidic soils, even the ratio of exchangeable to total metal content being higher in alkaline plots. To avoid a dangerous increase in soluble heavy metal content, it is important to decrease not only the large sulfur emissions of local pollutant sources, but also the alkaline pollutants. A similar concern must be taken into account when liming of acidic forest soils is planned.

High Temperature Superconducting Thick Films

DOEpatents

Arendt, Paul N.; Foltyn, Stephen R.; Groves, James R.; Holesinger, Terry G.; Jia, Quanxi

2005-08-23

An article including a substrate, a layer of an inert oxide material upon the surface of the substrate, (generally the inert oxide material layer has a smooth surface, i.e., a RMS roughness of less than about 2 nm), a layer of an amorphous oxide or oxynitride material upon the inert oxide material layer, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the amorphous oxide material layer is provided together with additional layers such as at least one layer of a buffer material upon the oriented cubic oxide material layer or a HTS top-layer of YBCO directly upon the oriented cubic oxide material layer. With a HTS top-layer of YBCO upon at least one layer of a buffer material in such an article, Jc's of 1.4×106 A/cm2 have been demonstrated with projected Ic's of 210 Amperes across a sample 1 cm wide.

Influence of design variables on radiation hardness of silicon MINP solar cells

NASA Technical Reports Server (NTRS)

Anderson, W. A.; Solaun, S.; Rao, B. B.; Banerjee, S.

1985-01-01

Metal-insulator-N/P silicon (MINP) solar cells were fabricated using different substrate resistivity values, different N-layer designs, and different I-layer designs. A shallow junction into an 0.3 ohm-cm substrate gave best efficiency whereas a deeper junction into a 1 to 4 ohm-cm substrate gave improved radiation hardness. I-layer design variation did little to influence radiation hardness.

[Seasonal dynamics of soil organic carbon mineralization for two forest types in Xiaoxing'an Mountains, China].

PubMed

Gao, Fei; Lin, Wei; Cui, Xiao-yang

2016-01-01

To investigate the seasonal dynamics of soil organic carbon (SOC) mineralization in Xiaoxing'an Mountain, we incubated soil samples collected from virgin Korean pine forest and broad-leaved secondary forest in different seasons in the laboratory and measured the SOC mineralization rate and cumulative SOC mineralization (Cm). We employed simultaneous reaction model to describe C mineralization kinetics and estimated SOC mineralization parameters including soil easily mineralizable C (C1), potentially mineralizable C (C₀). We also analyzed the relations between Cm, C₁and their influencing factors. Results showed that the incubated SOC mineralization rate and Cm for 0-5 cm soil layer decreased from early spring to late autumn, while for 5-10 cm soil layer the seasonal variation was not statistically significant for both forest types. The C₁ in 0-5 and 5-10 cm soil layers varied from 42.92-92.18 and 19.23-32.95 mg kg⁻¹, respectively, while the C₀ in 0-5 and 5-10 cm soil layers varied from 863.92-3957.15 and 434.15-865.79 mg · kg⁻¹, respec- tively. Both C₁ and C₀ decreased from early spring to late autumn. The proportions of C₀ in SOC for two forest types were 0.74%-2.78% and 1.11%-1.84% in 0-5 and 5-10 cm soil layers, respectively, and decreased from early spring to late autumn, indicating that SOC tended to become more stable as a whole from spring to autumn. The Cm and C₀ were significantly positively correlated to in situ soil water content and hot water-extractable carbohydrate content, but were not correlated to in situ soil temperature and cool water-extractable carbohydrate content. We concluded that soil labile organic carbon, soil physical and chemical properties contributed to the seasonal dynamics of SOC mineralization in the forests.

The structure of bacterial communities in natural and anthropogenic brown forest soils of the Botanical Garden on Murav'eva-Amurskogo Peninsula

NASA Astrophysics Data System (ADS)

Kovaleva, G. V.; Dobrovol'Skaya, T. G.; Golovacheva, A. V.

2007-05-01

The microbiological characterization of the brown forest soils in the territory of the Botanical Garden-Institute of the Far East Division of the Russian Academy of Sciences in southern Primor’e is given. The high humus content and weakly acid reaction of these soils were shown to provide the optimal conditions for the development of bacteria. In the brown forest soils differing in the thickness of the humus horizons, all the ecologic-trophic groups of bacteria were present and the bacterial communities were highly diverse. The structure of the bacterial communities was identical in all the organomineral horizons of the soils and varied greatly by the seasons. In the anthropogenically disturbed soils, the share of corynebacteria, which are resistant to stress and capable of the destruction of xenobiotics, decreased.

The earthworm gastrointestinal effect on the release of organic bound residues in soils

NASA Astrophysics Data System (ADS)

Du, J. H.

2018-03-01

Earthworm activities promote the release of bound residues and the digestive activities of earthworms contribute to the process. Earthworm digestive effects on bound residues can be divided into physical and chemical effects. Physical effects include gastrointestinal abrasion and mixing. The abrasion of soil and litter residues in earthworm gizzards and intestine can grind the food into fine particles, which increase the contact surface with microbial and promote the desorption of bound residues. Chemical effects are attributed to the secreted surfactant substances and digestive enzymes. The surfactants, especially at levels that lead to micellization, can enhance the desorption process of the organic contaminants that sored in the soil. The enzymes in earthworm digestive tracts can decompose the humus in soil, which may promote the release of organic residues that bind with humus.

Use of an ecosystem model for testing ecosystem response to inaccuracies of root and microflora productivity estimates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petersen, H.; O'Neill, R.V.; Gardner, R.H.

1984-01-01

A seventy-compartment model for a Danish beech forest ecosystem is described in outline. The unmodified model predicts considerable accumulation of wood litter and decreasing accumulation through secondary to final decomposition products. Increment rates are similar for all components of the detritus based food chain. Modification of fine root production rate produces strong, positive response for root litter, and less, but still significant, response for detritus, humus and the components of the decomposer food chain. Increase of microbial biomass with adjustments of metabolism and production causes reduced accumulation of detritus and humus. The soil organisms respond according to food source. Themore » use of the model for testing the sensitivity of the ecosystem to inaccuracies of rroot- and microflora estimates is discussed. 21 references, 3 figures, 1 table.« less

Ecological differentiation of diploid and polyploid cytotypes of Senecio carniolicus sensu lato (Asteraceae) is stronger in areas of sympatry.

PubMed

Sonnleitner, Michaela; Hülber, Karl; Flatscher, Ruth; Escobar García, Pedro; Winkler, Manuela; Suda, Jan; Schönswetter, Peter; Schneeweiss, Gerald M

2016-02-01

Ecological differentiation is recognized as an important factor for polyploid speciation, but little is known regarding whether the ecological niches of cytotypes differ between areas of sympatry and areas where single cytotypes occur (i.e. niche displacement). Ecological niches of four groups of Senecio carniolicus sensu lato (s.l.) (western and eastern diploid lineages, tetraploids and hexaploids) were characterized via Landolt indicator values of the accompanying vascular plant species and tested using multivariate and univariate statistics. The four groups of S. carniolicus s.l. were ecologically differentiated mainly with respect to temperature, light and soil (humus content, nutrients, moisture variability). Niche breadths did not differ significantly. In areas of sympatry hexaploids shifted towards sites with higher temperature, less light and higher soil humus content as compared with homoploid sites, whereas diploids and tetraploids shifted in the opposite direction. In heteroploid sites of tetraploids and the western diploid lineage the latter shifted towards sites with lower humus content but higher aeration. Niche displacement can facilitate the formation of stable contact zones upon secondary contact of polyploids and their lower-ploid ancestors and/or lead to convergence of the cytotypes' niches after they have attained non-overlapping ranges. Niche displacement is essential for understanding ecological consequences of polyploidy. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Factors and processes governing the C-14 content of carbonate in desert soils

NASA Technical Reports Server (NTRS)

Amundson, Ronald; Wang, Yang; Chadwick, Oliver; Trumbore, Susan; Mcfadden, Leslie; Mcdonald, Eric; Wells, Steven; Deniro, Michael

1994-01-01

A model is presented describing the factors and processes which determine the measured C-14 ages of soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with soil CO2. Carbon dioxide in soils is a mixture of CO2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing soil humus. The relative proportion of these two CO2 sources can greatly affect the initial C-14 content of pedogenic carbonate: the greater the contribution of humus-derived CO2, the greater the initial C-14 age of the carbonate mineral. For any given mixture of CO2 sources, the steady-state (14)CO2 distribution vs. soil depth can be described by a production/diffusion model. As a soil ages, the C-14 age of soil humus increases, as does the steady-state C-14 age of soil CO2 and the initial C-14 age of any pedogenic carbonate which forms. The mean C-14 age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate. This discrepancy increases the older a soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured C-14 age and true age. Although the production/diffusion model qualitatively explains the C-14 age of pedogenic carbonate vs. soil depth in many soils, other factors, such as climate change, may contribute to the observed trends, particularily in soils older than the Holocene.

Phenolic acids as bioindicators of fly ash deposit revegetation

DOE Office of Scientific and Technical Information (OSTI.GOV)

L. Djurdjevic; M. Mitrovic; P. Pavlovic

The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the 'Nikola Tesla-A' thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central partmore » of the deposit towards its edges. Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.« less

Phenomenon of organic carbon change in natural waters (system "catchment - Lake") of Russian Federation

NASA Astrophysics Data System (ADS)

Dinu, Marina; Tatyana, Moiseenko; Tatyana, Kremleva; Natalia, Gashkina

2015-04-01

In the last two decades in the Russian Federation was found significant increase in the concentration of dissolved organic carbon in many aqueous systems. Most obviously, these changes may be related to global warming. It is known that increasing the temperature dominate during dry periods and increases the concentration of nutrients, primary production increases, leading to an increase of the dissolved organic matter. At the same time, it is known that some of the increase in DOC may be largely due to a decrease of anthropogenic sulfur deposition and increasing organic matter in the soil. The European Russia (ER) is a region with substantial industrial emissions of sulphur. In the central part of ER are concentrated metallurgical productions. This has resulted in high concentrations of anthropogenic sulphate and an increase in the prevalence of acidification as well as a rise in metal concentrations in the lakes of North Kola. However, over the last 30 years, sulfur emissions in ?ola North have decreased substantially. The aim of this work was to explain the mechanisms to improve the content of natural organic matter and to assess its role in the processes of acidification and recovery of water quality while reducing the deposition of technogenic acid. The increasing of organic matter content in lake waters is being also observed for the totality of lakes in the Kola North. This conforms to the data reported by Skjelkvale et al. (2001a) which demonstrates the significant increase of DOC. Some authors explain the increased DOC levels by reduction in strong acid flow and return of water chemistry to its natural parameters of specifying organic matter concentrations in water. It is known that DOC level has a direct relationship with water color. In analyzing long-term study data with regard to the group of 75 lakes (obtained during 1990-2010) DOC is increased year-over-year, but the color decreased. The following chemical processes developing in water can explain this phenomenon. The water color is predominantly determined by large molecules of humus acids which molecular weight >1000 Da. Macromolecular organic substances of humus type can be dissociated in water with formation of a free proton, as well as enter into reactions of decomposition (hydrolysis) and disproportionation with formation of low-molecular weight fragments. Its fragments also are dissociated of proton (see the diagram below). Non-organic strong acids supplied from anthropogenic and natural sources may catalyze the above processes. The diagram of the organic substances destruction of humus origin is given below, where Ri means non-symmetrical fragments of a natural polymer, X_iH - functional groups of organic substances of humus origin, and n - number of protons. begin{equation*} HX_1-R_1-R_2-X_2H begin{array}{l} → R_1-X_1H + R_2-X_2H quad + quad R{^'}{_1} X1^- + R{^'}{_2} X2^- + nH+ → HX_1-R_1-R2 X_2- + - X_1R_1-R_2-X_2H + - X_1R_1-R2 X_2- + nH+ end{equation*} When strong acids get into a water environment humus acids are degraded into fractions. It could be supposed that the organic matter structure undergoes changes in natural waters, as the fraction of high-molecular weight humus acids decrease. As a consequence of interaction between humus substances and protons the humic acids precipitate to form bottom sediments, whereas fulvic acids remain in water. Fulvic acids are characterized by lower molecular weights (from 500 to 2000 Da) and exert an insignificant effect on the water color. Skelkvale, B.L., J.L. Stoddard, D.S. Jeffries, K. Torseth, T. Hogasen, J. Bowman, L. Mannio, Monteith, D.T., et al. 2005. Regional scale evidence for improvements in surface water chemistry 1990-2001. Environmental Pollution 137(1): 165-176. Moiseenko, T., L. Kudrjavzeva, I. Rodyshkin. 2001. The episodic acidification of small streams in the spring flood period of industrial polar region, Russia. Chemosphere 362: 45-50.

Apparent pollution of groundwater caused by natural formation of chloroform in forest soils

NASA Astrophysics Data System (ADS)

Jacobsen, O.; Laier, T.; Albers, C. N.; Hunkeler, D.

2011-12-01

Halogenated compounds are known to be formed in natural environments. Many of these compounds are similar to industrially produced compounds and are toxic or carcinogenic. High concentration of chloroform in groundwater is usually attributed to anthropogenic input, but we have found that the groundwater beneath some pristine areas contained chloroform exceeding 1 μg/L. We investigated four coniferous forests over a period of several years in order to measure the net-formation of chloroform. Field measurements of atmospheric and soil air concentrations of chloroform were monitored. Analyses of soil air at 40 cm depth in different parts of the forests and adjacent areas revealed an extremely large variation in chloroform concentration exceeding two orders of magnitude. Up to 100 ppbv was found in soil air under the spruce forest, to be compared to an ambient atmospheric concentration of 0.02 ppbv. The concentration of chloroform in soil air showed seasonal variation similar to that of CO2. Chloroform formation during incubation of undisturbed top-soil samples was found to be largest in soils from dense conifers stands with well-developed humus layers, while low chloroform formation occurred in soils from beech forest and agricultural grassland. We suggest that the mechanism behind the formation of chloroform is an unspecific chlorination of organic matter, caused by microbial activity in the soil. The aquifers are in fluvio-glacial sands with few layers of silt and a groundwater table from 4 to 7 m below the surface. In the shallowest parts of the aquifer, the groundwater has chloroform concentrations of 0.1 to 5 μg/L, and the groundwater is oxic with an age from 5 to 45 years using CFC-dating. Analyses of oxic groundwater > 40 years showed that it still contained chloroform at concentrations of 1 μg/L. Stable carbon isotopic analyses of chloroform from the uppermost groundwater in different parts of the forests and from soil water showed values from δ13C = -13 % to -27 %, corresponding to the ratio in natural organic materials and quite different from those of industrial products and from contaminated groundwater (δ13C = -46 % to -63 %). The isotopic ratio showed a minor decrease with depth due to a decomposition of chloroform. Measurements in a groundwater transect in one of the forest areas indicated that anoxic conditions in the groundwater depleted chloroform totally.

Facies implications of Trichichnus and Chondrites in turbidites and hemipelagites, Marnoso-arenacea Formation (Miocene), northern Apennines, Italy

DOE Office of Scientific and Technical Information (OSTI.GOV)

McBride, E.F.; Picard, M.D.

Trichichnus, a thread-like burrow possibly the work of sipunculan worms, is widespread in Bouma E (turbidite claystone) and H (hemipelagic claystone) layers and some thin turbidite sandstone beds in basin-plain and outer fan-lobe deposits of the Marnoso-arenacea Formation. Trichichnus closely resembles that described elsewhere in chalk and marlstone, although the burrows are smaller (mean diameter=0.13 mm) and burrow curvature is tighter. Trichichnus fills are darker than the host claystone because of high organic content and disseminated pyrite. Any distinctive internal structure of the burrow wall or fill was destroyed by pyrite growth. Trichichnus is most abundant in Bouma E layers,more » where burrow spacing ranges from 0.4 to 50 cm and burrows extend to depths of 160 cm. The Trichichnus maker commonly burrowed vertically down through E and D layers (clay and silt) and then horizontally on top of C layers (sand). The burrows also vertically penetrate Bouma C sandstone layers up to 6 cm thick, but they are rare in beds thicker than 3 cm. They are less abundant or not well displayed in H layers where Chondrites predominates. Trichichnus overprints Chondrites. Following deposition of the Contessa megaturbidite, which exceeds 9 m in thickness, the sediment surface was repopulated chiefly by Trichichnus and Chondrites producers. Trichichnus extends 160 cm below the top of the Contessa, whereas Chondrites extend only to 64 cm. This suggests a greater tolerance of Trichichnus makers to low in situ oxygen levels. The near absence of laminations in the E division of the Contessa megabed may be the result of Trichichnus burrows that were not pyritized and which lack textural identity.« less

Buffer layers on metal alloy substrates for superconducting tapes

DOEpatents

Jia, Quanxi; Foltyn, Stephen R.; Arendt, Paul N.; Groves, James R.

2004-10-05

An article including a substrate, at least one intermediate layer upon the surface of the substrate, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the at least one intermediate layer, and a layer of a SrRuO.sub.3 buffer material upon the oriented cubic oxide material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon the layer of a SrRuO.sub.3 buffer material layer. With a HTS top-layer of YBCO upon at least one layer of the SrRuO.sub.3 buffer material in such an article, J.sub.c 's of up to 1.3.times.10.sup.6 A/cm.sup.2 have been demonstrated with projected I.sub.c 's of over 200 Amperes across a sample 1 cm wide.

[Species composition and diversity of soil mesofauna in the 'Holy Hills' fragmentary tropical rain forest of Xishuangbanna, China].

PubMed

Yang, X; Sha, L

2001-04-01

The species composition and diversity of soil mesofauna were examined in fragmented dry tropical seasonal rainforest of tow 'Holy Hills' of Dai nationality, compared with the continuous moist tropical seasonal rain forest of Nature Reserve in Xishuangbanna area. 5 sample quadrats were selected along the diagonal of 20 m x 20 m sampling plot, and the samples of litterfall and 0-3 cm soil were collected from each 50 cm x 10 cm sample quadrat. Animals in soil sample were collected by using dry-funnel(Tullgren's), were identified to their groups according to the order. The H' index, D.G index and the pattern of relative abundance of species were used to compare the diversity of soil mesofauna. The results showed that the disturbance of vegetation and soil resulted by tropical rainforest fragmentation was the major factor affecting the diversity of soil mesofauna. Because the fragmented forest was intruded by some pioneer tree species and the "dry and warm" effect operated, this forest had more litterfall on the floor and more humus in the soil than the continuous moist rain forest. The soil condition with more soil organic matter, total N and P, higher pH value and lower soil bulk density became more favorable to the soil mesofauna. Therefore, the species richness, abundance and diversity of soil mesofauna in fragmented forests were higher than those in continuous forest, but the similarity of species composition in fragmented forest to the continuous forest was minimal. Soil mesofauna diversity in fragmented forests did not change with decreasing fragmented area, indicating that there was no species-area effect operation in this forest. The pattern of relative abundance of species in these forest soils was logarithmic series distribution.

Layer-dependent electrical and optoelectronic responses of ReSe2 nanosheet transistors.

PubMed

Yang, Shengxue; Tongay, Sefaattin; Li, Yan; Yue, Qu; Xia, Jian-Bai; Li, Shun-Shen; Li, Jingbo; Wei, Su-Huai

2014-07-07

The ability to control the appropriate layer thickness of transition metal dichalcogenides (TMDs) affords the opportunity to engineer many properties for a variety of applications in possible technological fields. Here we demonstrate that band-gap and mobility of ReSe2 nanosheet, a new member of the TMDs, increase when the layer number decreases, thus influencing the performances of ReSe2 transistors with different layers. A single-layer ReSe2 transistor shows much higher device mobility of 9.78 cm(2) V(-1) s(-1) than few-layer transistors (0.10 cm(2) V(-1) s(-1)). Moreover, a single-layer device shows high sensitivity to red light (633 nm) and has a light-improved mobility of 14.1 cm(2) V(-1) s(-1). Molecular physisorption is used as "gating" to modulate the carrier density of our single-layer transistors, resulting in a high photoresponsivity (Rλ) of 95 A W(-1) and external quantum efficiency (EQE) of 18 645% in O2 environment. This work highlights the fact that the properties of ReSe2 can be tuned in terms of the number of layers and gas molecule gating, and single-layer ReSe2 with appropriate band-gap is a promising material for future functional device applications.

Room temperature multiferroic properties of (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raghavan, C.M.; Kim, H.J.; Kim, J.W.

2013-11-15

Graphical abstract: - Highlights: • Chemical solution deposition of (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}–NiFe{sub 2}O{sub 4} double layered thin film. • Studies on structural, electrical and multiferroic properties. • NiFe{sub 2}O{sub 4} acts as both resistive buffer layer and magnetic source. - Abstract: (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film was prepared on a Pt(111)/Ti/SiO{sub 2}/Si(100) substrate by a chemical solution deposition method. X-ray diffraction and Raman scattering spectroscopy studies confirmed the formation of the distorted rhombohedral perovskite and the inverse spinel cubic structures for the (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4}more » double layered thin film. The (Bi{sub 0.95}La{sub 0.05})(Fe{sub 0.97}Mn{sub 0.03})O{sub 3}/NiFe{sub 2}O{sub 4} double layered thin film exhibited well saturated ferromagnetic (2 M{sub r} of 18.1 emu/cm{sup 3} and 2H{sub c} of 0.32 kOe at 20 kOe) and ferroelectric (2P{sub r} of 60 μC/cm{sup 2} and 2E{sub c} of 813 kV/cm at 866 kV/cm) hysteresis loops with low order of leakage current density (4.5 × 10{sup −6} A/cm{sup 2} at an applied electric field of 100 kV/cm), which suggest the ferroelectric and ferromagnetic multi-layers applications in real devices.« less

Silicon-on Ceramic Process: Silicon Sheet Growth and Device Development for the Large-area Silicon Sheet and Cell Development Tasks of the Low-cost Solar Array Project

NASA Technical Reports Server (NTRS)

Chapman, P. W.; Zook, J. D.; Heaps, J. D.; Grung, B. L.; Koepke, B.; Schuldt, S. B.

1979-01-01

The technical and economic feasibility of producing solar cell-quality silicon was investigated. This was done by coating one surface of carbonized ceramic substrates with a thin layer of large-grain polycrystalline silicon from the melt. Significant progress in the following areas was demonstrated: (1) fabricating a 10 sq cm cell having 9.9 percent conversion efficiency; (2) producing a 225 sq cm layer of sheet silicon; and (3) obtaining 100 microns thick coatings at pull speed of 0.15 cm/sec, although approximately 50 percent of the layer exhibited dendritic growth.

[Root anatomical structure and hydraulic traits of three typical shrubs on the sandy lands of northern Shaanxi Province, China].

PubMed

Ai, Shao-shui; Li, Yang-yang; Chen, Jia-cun; Chen, Wei-yue

2015-11-01

Root xylem anatomical structure and hydraulic traits of three typical shrubs, i.e., Salix psammophila, Caragana korshinskii and Hippophae rhamnoides, within two soil layers (0-20 cm and 30-50 cm) were compared. The results showed that S. psammophila had a higher leaf water potential than C. korshinskii and H. rhamnoides, the average maximum and minimum lumen diameter (d(max) and d(min), respectively), the average lumen area of vessels (Alum) and the ratio of lumen area of all vessels to xylem area (Aves/Axyl) in S. psammophila roots were also significantly higher than those in C. korshinskii and H. rhamnoides, and the root vessel density (VD) in S. psammophila was the same as that in H. rhamnoides but significantly higher than that in C. korshinskii. Root hydraulic conductivity in S. psammophila was 5 times of C. korshinskii and 2.8 times of H. hamnoides. The vulnerability index in S. psammophila roots was similar to that in C. korshinskii but higher than that in H. hamnoides. S. psammophila belonged to a water-spending species, whereas both C. korshinskii and H. rhamnoides were water-saving species, and C. korshinskii was more drought-resistant than H. rhamnoides. There was no difference of d(max), d(min) and Alum between roots in two soil layers, but roots within in the 30-50 cm soil layer had larger VD and Aves/Axyl. The root specific hydraulic conductivity within the 30-50 cm soil layer was significantly higher than within the surface soil layer, whereas the vulnerability index within the 30-50 cm soil layer was smaller, indicating roots in deep soil layers had higher hydraulic transport efficiency and lower hydraulic vulnerability.

[Characteristics of main layer and regeneration layer of Haloxylon ammodendron plantations at different ages on the southern edge of the Gurbantunggut Desert, Northwest China].

PubMed

Chen, Qi Min; Luo, Qing Hong; Ning, Hu Sen; Zhao, Cheng Yi; Duan, Wen Biao

2017-03-18

The population structure characteristics, natural regeneration, and the influential factors of Haloxylon ammodendron plantations at six different stand ages on the southern edge of the Gurbantunggut Desert were studied. The results showed that H. ammodendron plantation at the stand age of 7 could naturally regenerate. At the stand age of 17, the densities of the seedlings (＜30 cm height), saplings (30≤H＜50 height), and small trees (≥50 cm height) reached optimal class, and the mean height and base diameter of the small tress reached 1.10 m and 1.91 cm, respectively. The parent trees in H. ammodendron plantation at the stand age of 20 grew best. The height of 35% individuals grew up to 2.50-3.00 m, and the basal stem diameter of 23.1% individuals grew up to 8.00-10.00 cm. The height and diameter growth of the parent trees in H. ammodendron plantation at the stand age of 33 apparently declined, but the regeneration ability by natural seed dispersal was still strong. The regeneration density of natural seed dispersal showed the greatest correlation with the available nitrogen content in 0-100 cm soil layer (0.87), followed by the soil rapidly available phosphorus content (0.84) and the soil water content (0.79). The soils with pH 8.1-8.6 did not limit the nutrient growth of the regeneration layer. In the main stand layer, the individual density of whole regeneration layer showed the greatest correlation with the biomass of the parent trees (0.77), while the density of regeneration layer of the small trees showed the greatest correlation with the planting density (0.71) and the age of the parent trees (0.70).

[Dynamics of soil physical properties and biological soil crust during the vegetation restoration process of abandoned croplands in the Ordos Plateau, China].

PubMed

Cai, Wen Tao; Li, He Yi; Lai, Li Ming; Zhang, Xiao Long; Guan, Tian Yu; Zhou, Ji Hua; Jiang, Lian He; Zheng, Yuan Run

2017-03-18

A series of typical abandoned croplands in the regions of Ruanliang and Yingliang in the Ordos Plateau, China, were selected, and dynamics of the surface litter, biological soil crust and soil bulk density, soil texture, and soil moisture in different soil layers were investigated. The results showed that in the abandoned cropland in Ruanliang, the clay particle content and surface litter of the surface soil layer (0-10 cm) increased during the restoration process, while that of soil bulk density substantially decreased and soil water content slightly increased in the surface soil. In the medium soil layer (10-30 cm), the clay particle content increased and the soil water content slightly decreased. In the deep soil layer (30-50 cm), there was a relatively large variation in the physical properties. In the abandoned cropland in Yingliang, the coverage of litter and the coverage and thickness of the biological soil crust increased during the abandonment process. The surface soil bulk density, soil clay particle content and soil water content remained constant in 0-10 cm soil layer, while the physical properties varied substantially in 10-40 cm soil layer. The shallow distribution of the soil water content caused by the accumulation of the litter and clay particles on the soil surface might be the key reason of the replacement of the semi-shrub Artemisia ordosica community with a perennial grass community over the last 20 years of the abandoned cropland in Ruanliang. The relatively high soil water content in the shallow layer and the development of the biological soil crust might explain why the abandoned cropland in Yingliang was not invaded by the semi-shrub A. ordosica during the restoration process.

Metallic conduction induced by direct anion site doping in layered SnSe2.

PubMed

Kim, Sang Il; Hwang, Sungwoo; Kim, Se Yun; Lee, Woo-Jin; Jung, Doh Won; Moon, Kyoung-Seok; Park, Hee Jung; Cho, Young-Jin; Cho, Yong-Hee; Kim, Jung-Hwa; Yun, Dong-Jin; Lee, Kyu Hyoung; Han, In-taek; Lee, Kimoon; Sohn, Yoonchul

2016-01-21

The emergence of metallic conduction in layered dichalcogenide semiconductor materials by chemical doping is one of key issues for two-dimensional (2D) materials engineering. At present, doping methods for layered dichalcogenide materials have been limited to an ion intercalation between layer units or electrostatic carrier doping by electrical bias owing to the absence of appropriate substitutional dopant for increasing the carrier concentration. Here, we report the occurrence of metallic conduction in the layered dichalcogenide of SnSe2 by the direct Se-site doping with Cl as a shallow electron donor. The total carrier concentration up to ~10(20) cm(-3) is achieved by Cl substitutional doping, resulting in the improved conductivity value of ~170 S · cm(-1) from ~1.7 S · cm(-1) for non-doped SnSe2. When the carrier concentration exceeds ~10(19) cm(-3), the conduction mechanism is changed from hopping to degenerate conduction, exhibiting metal-insulator transition behavior. Detailed band structure calculation reveals that the hybridized s-p orbital from Sn 5s and Se 4p states is responsible for the degenerate metallic conduction in electron-doped SnSe2.

Kinetic multi-layer model of the epithelial lining fluid (KM-ELF): Reactions of ozone and OH with antioxidants and surfactant molecules

NASA Astrophysics Data System (ADS)

Lakey, Pascale; Pöschl, Ulrich; Shiraiwa, Manabu

2015-04-01

Oxidants cause damage to biosurfaces such as the lung epithelium unless they are effectively scavenged. The respiratory tract is covered in a thin layer of fluid which extends from the nasal cavity to the alveoli and contain species that scavenge ozone and other incoming oxidants. The kinetic multi-layer model of the epithelial lining fluid (KM-ELF) has been developed in order to investigate the reactions of ozone and OH with antioxidants (ascorbate, uric acid, glutathione and α-tocopherol) and surfactant lipids and proteins within the epithelial lining fluid (ELF). The model incorporates different processes: gas phase diffusion, adsorption and desorption from the surface, bulk phase diffusion and known reactions at the surface and in the bulk. The ELF is split into many layers: a sorption layer, a surfactant layer, a near surface bulk layer and several bulk layers. Initial results using KM-ELF indicate that at ELF thicknesses of 80 nm and 1 × 10-4cm the ELF would become rapidly saturated with ozone with saturation occurring in less than a second. However, at an ELF thickness of 1 × 10-3cm concentration gradients were observed throughout the ELF and the presence of antioxidants reduced the O3 reaching the lung cells and tissues by 40% after 1 hour of exposure. In contrast, the antioxidants were efficient scavengers of OH radicals, although the large rate constants of OH reacting with the antioxidants resulted in the antioxidants decaying away rapidly. The chemical half-lives of the antioxidants and surface species were also calculated using KM-ELF as a function of O3 and OH concentration and ELF thickness. Finally, the pH dependence of the products of reactions between antioxidants and O3 were investigated. The KM-ELF model predicted that a harmful ascorbate ozonide product would increase from 1.4 × 1011cm-3at pH 7.4 to 1.1 × 1014 cm-3 at pH 4after 1 hour although a uric acid ozonide product would decrease from 2.0 × 1015cm-3to 5.9 × 1012cm-3.

Lear jet boundary layer/shear layer laser propagation experiments

NASA Technical Reports Server (NTRS)

Gilbert, K.

1980-01-01

Optical degradations of aircraft turbulent boundary layers with shear layers generated by aerodynamic fences are analyzed. A collimated 2.5 cm diameter helium-neon laser (0.63 microns) traversed the approximate 5 cm thick natural aircraft boundary layer in double pass via a reflective airfoil. In addition, several flights examined shear layer-induced optical degradation. Flight altitudes ranged from 1.5 to 12 km, while Mach numbers were varied from 0.3 to 0.8. Average line spread function (LSF) and Modulation Transfer Function (MTF) data were obtained by averaging a large number of tilt-removed curves. Fourier transforming the resulting average MTF yields an LSF, thus affording a direct comparison of the two optical measurements. Agreement was good for the aerodynamic fence arrangement, but only fair in the case of a turbulent boundary layer. Values of phase variance inferred from the LSF instrument for a single pass through the random flow and corrected for a large aperture ranged from 0.08 to 0.11 waves (lambda = .63 microns) for the boundary layer. Corresponding values for the fence vary from 0.08 to 0.16 waves. Extrapolation of these values to 10.6 microns suggests negligible degradation for a CO2 laser transmitted through a 5 cm thick, subsonic turbulent boundary layer.

[Diversity of soil mesofauna in Northern Taiga biogeocenosises of the Kamennaya river basin (Karelia)].

PubMed

Rybalov, L B; Kamaev, I O

2011-01-01

The population of soil mesofauna in the basin of the small river subzone of the northern taiga (Karelia) has been investigated. It was shown that indexes of the number and mass of soil mesofauna in the landscape-ecological row ofbiogeocenosises are maximal in floodplain soils. The taxonomic composition and structure of domination of the soil mesofauna population depends on the location of biogeocenosis in the landscape: earthworms are dominants in riverine floodplain biogeocenosises, and larvae of elaterids and spiders prevail in the places outside of floodplains. The abundance of saprophytic invertebrates in floodplain biogeocenosises results in formation of humus of the mull type. A group of animals with mixed type of nutrition dominates in the places outside of floodplain soils that are related with humus of the moder-mor type. The population of rove beetles (Staphylinidae) allows the division of biogeocenosises into two groups according to their position in the landscape.

In vitro genotoxicity of chlorinated drinking water processed from humus-rich surface water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liimatainen, A.; Grummt, T.

Chlorination by-products of drinking waters are capable of inducing sister chromatid exchanges (SCE) and chromosome aberrations (CA) in vitro, in addition to their mutagenic activity in the Ames test. Finnish drinking waters, processed from humus-rich surface water using chlorine disinfection, have been found to be highly mutagenic in the Ames' test. The highest activities have been found in the acidic, non-volatile fraction of the water concentrates using tester strain TA100 without metabolic activation by S9mix. The mutagenicities have varied between 500 and 14,000 induced revertants per liter. These figures are one to two magnitudes higher than those reported elsewhere. Themore » authors studied five Finnish drinking water samples for their potency to exert genotoxic effects, SCEs and CAs, in mammalian cells in vitro (human peripheral lymphocytes and Chinese hamster lung fibroblasts).« less

Agrogenic degradation of soils in Krasnoyarsk forest-steppe

NASA Astrophysics Data System (ADS)

Shpedt, A. A.; Trubnikov, Yu. N.; Zharinova, N. Yu.

2017-10-01

Agrogenic degradation of soils in Krasnoyarsk forest-steppe was investigated. Paleocryogenic microtopography of microlows and microhighs in this area predetermined the formation of paragenetic soil series and variegated soil cover. Specific paleogeographic conditions, thin humus horizons and soil profiles, and long-term agricultural use of the land resulted in the formation of soils unstable to degradation processes and subjected to active wind and water erosion. Intensive mechanical soil disturbances during tillage and long-term incorporation of the underlying Late Pleistocene (Sartan) calcareous silty and clay loams into the upper soil horizons during tillage adversely affected the soil properties. We determined the contents of total and labile humus and easily decomposable organic matter and evaluated the degree of soil exhaustion. It was concluded that in the case of ignorance of the norms of land use and soil conservation practices, intense soil degradation would continue leading to complete destruction of the soil cover within large areas.

Coal-derived humus: plant growth effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freeman, P.G.; Fowkes, W.W.

The growth-promoting properties of coal-derived humus were tested by a variety of bioassay methods. Humate materials used included leonardite, a form of naturally oxidized lignite, and humic acids extracted from leonardite. It was found that the greatest effects were evident when water-soluble humic acid was applied to excised root tips. No significant short-term effect was noted when water-soluble humic acid was applied to stem or coleoptile sections. Root initiation was promoted in bean stems when high concentrations of coal-derived humate were applied. Gross weight of tomato plants was increased by up to 40 percent when coal-derived humates were added inmore » concentrations of 10/sup 1/ to 10/sup 4/ ppM to the nutrient in a hydroponic growth test of 6 weeks' duration. It is concluded that coal-derived humate promotes the uptake of minerals, specifically iron, by serving as a metal chelate.« less

In-Situ Grown P-N Junctions in MERCURY(1-X) Cadmium(x) Telluride for IR Detectors.

NASA Astrophysics Data System (ADS)

Rao, Vithal Rajaram

In-situ grown p-n junctions in mercury cadmium telluride (Hg_{1-x}Cd _{x}Te with x between 0.2-0.3) were fabricated and characterized in this study. Fabrication of these junctions involved the growth of p-n structures at 370^circC on CdTe substrates by Organometallic Vapor Phase Epitaxy. P-type doping with arsenic was achieved by using tertiarybutylarsine as the precursor. N-type doping was obtained either with indium, using trimethylindium as the precursor or by leaving the layer undoped. These p-n structures were processed to fabricate photodiodes. Their electrical performance was evaluated and conclusions regarding current mechanisms which determine their behavior were drawn. By varying the Hg pressure between 0.07-0.13 atm, p-type doping level in the 10^{16 }/cm^3-rm2times10 ^{17}/cm^3 range was achieved. At higher values of Hg pressure, the arsenic doping level in the layer increased significantly. This is possibly due to an increase in Te vacancies, allowing arsenic to occupy more group VI sites where they behave as acceptors. The activation efficiency of arsenic in the layers was measured to be equal to 50%. A high temperature anneal at 415 ^circC for 15 minutes did not result in any increase in the activation efficiency, possibly indicating the presence of stable As-complexes in the layer. Growth of p^+n structures was carried out in a single run. The acceptor concentration in the p-type cap layer was 5-rm10times10 ^{16}/cm^3. Indium doped n-type base layers had a carrier concentration of 1- rm2times10^{16}/cm^3 , while undoped layers had a n-type background carrier concentration of 4-rm6times10^ {14}/cm^3. The cap layer was 3 μm thick with x = 0.30, while the base layer was 8mum thick with x = 0.26. Under the growth conditions, arsenic showed a diffusion coefficient of rm2times10 ^{13}cm^2/s, which was higher than the interdiffusion coefficient of the alloy junction. This resulted in placement of the p-n junction in the lower bandgap base layer, which is necessary for high quantum efficiency devices. Photodiodes showed a cutoff wavelength of 7.5 mum, which correlates with the alloy composition of the base layer. Measured R_0 A of these diodes varied between 1-100 ohm-cm ^2. In the lower R_0A diodes, reverse bias was dominated by surface currents, possibly due to degradation of the passivating layer. Diodes with higher R_0A showed under reverse bias that trap assisted tunneling current dominated their performance. The origin of these traps is process related and could correspond to the presence of inactivated arsenic close to the p-n junction. Forward bias was dominated by diffusion and recombination currents, while the presence of additional leakage currents was evident.

Irrigation depth far exceeds water uptake depth in an oasis cropland in the middle reaches of Heihe River Basin

PubMed Central

Yang, Bin; Wen, Xuefa; Sun, Xiaomin

2015-01-01

Agricultural irrigation in the middle reaches of the Heihe River Basin consumes approximately 80% of the total river water. Whether the irrigation depth matches the water uptake depth of crops is one of the most important factors affecting the efficiency of irrigation water use. Our results indicated that the influence of plastic film on soil water δ18O was restricted to 0–30 cm soil depth. Based on a Bayesian model (MixSIR), we found that irrigated maize acquired water preferentially from 0–10 cm soil layer, with a median uptake proportion of 87 ± 15%. Additionally, maize utilised a mixture of irrigation and shallow soil water instead of absorbing the irrigation water directly. However, only 24.7 ± 5.5% of irrigation water remained in 0–10 cm soil layer, whereas 29.5 ± 2.8% and 38.4 ± 3.3% of the irrigation water infiltrated into 10–40 cm and 40–80 cm layers. During the 4 irrigation events, approximately 39% of the irrigation and rainwater infiltrated into soil layers below 80 cm. Reducing irrigation amount and developing water-saving irrigation methods will be important strategies for improving the efficiency of irrigation water use in this area. PMID:26463010

Isotopic evidence for the formation of unusually humus-rich soils in the Baltic region

NASA Astrophysics Data System (ADS)

Leinweber, Peter; Acksel, Andre; Kühn, Peter

2017-04-01

Arable mineral soils in the Pleistocene landscape of Northern Germany usually contain about 4 to 8 kg of organic C (Corg) per m2, most of which is visually recognizable concentrated in the tilled topsoil horizon. Some unusually humus-rich (10 to 20 kg Corg m-2), and deeply (> 70 cm) dark-colored soils in coastal regions with mollic properties have been classified as Chernozems. Their location far away from the middle German and Central European Chernozem regions, absence of steppe vegetation and semi-arid climate conditions make classical pedogenetic theories doubtful. However, non-targeted mass spectrometric analyses of soil organic matter (SOM) composition revealed great similarities with typical Chernozems worldwide (Thiele-Bruhn et al., 2014) and made alternative (e.g. waterlogged) pathways of SOM accumulation unlikely. Subsequent detailed multi-method SOM analyses down the soil profiles revealed relative enrichments in cyclic ("black carbon") and heterocyclic organic compounds in the deeper, bioturbated horizons. These were plausibly explained by the input of combustion residues, likely originating from anthropogenic activities because spots of these soils coincided with archeological artifacts of early settlements (Acksel et al., 2016). However, these finding could not completely explain the genesis of Chernozems in the Baltic region. Therefore, we actually explored isotope analyses (12/13C, 13/14C, 14/15N, 32/34S) to find out the origin of these unusual SOM enrichments and the time period in which it occurred. The results will be compiled to a consistent hypothesis on the formation of these soils in the Baltic and other Northern European regions. References Acksel, A., W. Amelung, P. Kühn, E. Gehrt, T. Regier, P. Leinweber. 2016. Soil organic matter characteristics as indicator of Chernozem genesis in the Baltic Sea region. Geoderma Regional 7, 187-200. Thiele-Bruhn, S., Leinweber P., Eckhardt K.-U., Siem H.K., Blume H.-P. 2014. Identifying Chernozem properties of Black Soils in the Baltic region of Germany from soil organic matter composition investigated by Py-FIMS. Geoderma 213, 144-154.

Observations of transitional tidal boundary layers and their impact on sediment transport in the Great Bay, NH

NASA Astrophysics Data System (ADS)

Koetje, K. M.; Foster, D. L.; Lippmann, T. C.

2017-12-01

Observations of the vertical structure of tidal flows obtained in 2016 and 2017 in the Great Bay Estuary, NH show evidence of transitional tidal boundary layers at deployment locations on shallow mudflats. High-resolution bottom boundary layer currents, hydrography, turbidity, and bed characteristics were observed with an acoustic Doppler current profiler (ADCP), an acoustic Doppler velocimeter (ADV), conductivity-depth-temperature (CTD) sensors, optical backscatter sensors, multibeam bathymetric surveys, and sediment grab samples and cores. Over the 2.5 m tidal range and at water depths ranging from 0.3 m to 1.5 m at mean lower low water, peak flows ranged from 10 cm/s to 30 cm/s and were primarily driven by the tides. A downward-looking ADCP captured the velocity profile over the lowest 1 m of the water column. Results consistently show a dual-log layer system, with evidence of a lower layer within 15 cm of the bed, another layer above approximately 30 cm from the bed, and a transitional region where the flow field rotates between that the two layers that can be as much as 180 degrees out of phase. CTD casts collected over a complete tidal cycle suggest that the weak thermohaline stratification is not responsible for development of the two layers. On the other hand, acoustic and optical backscatter measurements show spatial and temporal variability in suspended sediments that are dependant on tidal phase. Current work includes an examination of the relationship between sediment concentrations in the water column and velocity profile characteristics, along with an effort to quantify the impact of rotation and dual-log layers on bed stress.

Control of indium tin oxide anode work function modified using Langmuir-Blodgett monolayer for high-efficiency organic photovoltaics

NASA Astrophysics Data System (ADS)

Yokokura, Yuya; Dogase, Tomomichi; Shinbo, Tatsuki; Nakayashiki, Yuya; Takagi, Yusuke; Ueda, Kazuyoshi; Sarangerel, Khayankhyarvaa; Delgertsetseg, Byambasuren; Ganzorig, Chimed; Sakomura, Masaru

2017-08-01

The use of Langmuir-Blodgett (LB) monolayers to modify the indium tin oxide (ITO) work function and thus improve the performance of zinc phthalocyanine (ZnPc)/fullerene (C60)-based and boron subphthalocyanine chloride (SubPc)/C60-based small molecule organic photovoltaic devices (OPVs) was examined. In general, LB precursor compounds contain one or more long alkyl chain substituents that can act as spacers to prevent electrical contact with adjoining electrode surfaces. As one example of such a compound, arachidic acid (CH3(CH2)18COOH) was inserted in the forms of one-layer, three-layer or five-layer LB films between the anode ITO layer and the p-type layer in ZnPc-C60-based OPVs to investigate the effects of the long alkyl chain group when it acts as an electrically insulating spacer. The short-circuit current density (Jsc) values of the OPVs with the three- and five-layer inserts (1.78 mA.cm-2 and 0.61 mA.cm-2, respectively) were reduced dramatically, whereas the Jsc value for the OPV with the single-layer insertion (2.88 mA.cm-2) was comparable to that of the OPV without any insert (3.14 mA.cm-2). The ITO work function was shifted positively by LB deposition of a surfactant compound, C9F19C2H4-O-C2H4-COOH (PFECA), which contained a fluorinated head group. This positive effect was maintained even after formation of an upper p-type organic layer. The Jsc and open-circuit voltage (Voc) of the SubPc-C60-based OPV with the LB-modified ITO layers were effectively enhanced. As a result, a 42% increase in device efficiency was achieved.

A simple analytical model of coupled single flow channel over porous electrode in vanadium redox flow battery with serpentine flow channel

NASA Astrophysics Data System (ADS)

Ke, Xinyou; Alexander, J. Iwan D.; Prahl, Joseph M.; Savinell, Robert F.

2015-08-01

A simple analytical model of a layered system comprised of a single passage of a serpentine flow channel and a parallel underlying porous electrode (or porous layer) is proposed. This analytical model is derived from Navier-Stokes motion in the flow channel and Darcy-Brinkman model in the porous layer. The continuities of flow velocity and normal stress are applied at the interface between the flow channel and the porous layer. The effects of the inlet volumetric flow rate, thickness of the flow channel and thickness of a typical carbon fiber paper porous layer on the volumetric flow rate within this porous layer are studied. The maximum current density based on the electrolyte volumetric flow rate is predicted, and found to be consistent with reported numerical simulation. It is found that, for a mean inlet flow velocity of 33.3 cm s-1, the analytical maximum current density is estimated to be 377 mA cm-2, which compares favorably with experimental result reported by others of ∼400 mA cm-2.

Evaluation of AISI 4140 Steel Repair Without Post-Weld Heat Treatment

NASA Astrophysics Data System (ADS)

Silva, Cleiton C.; de Albuquerque, Victor H. C.; Moura, Cícero R. O.; Aguiar, Willys M.; Farias, Jesualdo P.

2009-04-01

The present work evaluates the two-layer technique on the heat affected zone (HAZ) of AISI 4140 steel welded with different heat input levels between the first and second layer. The weld heat input levels selected by the Higuchi test were 5/5, 5/10, and 15/5 kJ/cm. The evaluation of the refining and/or tempering of the coarsened grain HAZ of the first layer was carried out using metallographic tests, microhardness measurements, and the Charpy-V impact test. The tempering of the first layer was only reached when the weld heat input ratio was 5/5 kJ/cm. The results of the Charpy-V impact test showed that the two-layer technique was efficient, from the point of view of toughness, since the toughness values reached were greater than the base metal for all weld heat input ratios applied. The results obtained indicate that the best performance of the two-layer deposition technique was for the weld heat input ratio 5/5 kJ/cm employing low heat input.

[Characterization of soil humus by FTIR spectroscopic analyses after being inoculated with different microorganisms plus wheat straw].

PubMed

Wang, Shuail; Dou, Sen; Liu, Yan-Li; Li, Hui-Min; Cui, Jun-Tao; Zhang, Wei; Wang, Cheng-Yu

2012-09-01

The effects of different microbial communities on the structural characteristics of humus from the black soil amended with wheat straw were studied by FTIR Spectroscopy. The results indicated that (1) The structure and amount of functional groups in the water soluble substances (WSS) was tremendously influenced by the tested microorganisms, of which the amino and aryl ether was degraded rapidly in the inoculation process, and in the meantime, the content of hydroxyl groups was significantly reduced. The bacteria was helpful to increasing the amount of aliphatic hydrocarbons, while the other inoculated treatments were contrary. At the end of culture, the phenols and polysaccharides were gradually consumed, but the content of carboxyl groups had an increasing trend. (2) In the aspect of reducing hydroxyl groups of fulvic acid (FA), the role of actinomycetes was the biggest. The fungi had the biggest effect in improving the net generation of FA content. In addition, the fungi was conducive to improve the contents of carboxyl groups and carbohydrates of FA fraction. Except the mixed strains, the other treatments were all beneficial to the degradation of polysaccharide in the FA fraction, whose rate was greater than the decomposition of lipids. (3) The bacteria, actinomycetes and fungi were all helpful to reducing the amount of aliphatic hydrocarbons of HA fraction except the mixed strains. The content of carboxyl was effectively increased by fungi, but the effect of bacteria was contrary. The tested microorganisms could consume and utilize the polysaccharides of HA fraction, which could transform the humic-like fractions from plant residues into the real humus of soil.

Humic substance-mediated Fe(III) reduction by a fermenting Bacillus strain from the alkaline gut of a humus-feeding scarab beetle larva.

PubMed

Hobbie, Sven N; Li, Xiangzhen; Basen, Mirko; Stingl, Ulrich; Brune, Andreas

2012-06-01

Humus-feeding macroinvertebrates play an important role in the transformation of soil organic matter. Their diet contains significant amounts of redox-active components such as iron minerals and humic substances. In soil-feeding termites, acid-soluble Fe(III) and humic acids are almost completely reduced during gut passage. Here, we show that the reduction of Fe(III) and humic acids takes place also in the alkaline guts of scarab beetle larvae. Sterilized gut homogenates of Pachnoda ephippiata no longer converted Fe(III) to Fe(II), indicating an essential role of the gut microbiota in the process. From Fe(III)-reducing enrichment cultures inoculated with highly diluted gut homogenates, we isolated several facultatively anaerobic, alkali-tolerant bacteria that were closely related to metal-reducing isolates in the Bacillus thioparans group. Strain PeC11 showed a remarkable capacity for dissimilatory Fe(III) reduction, both at pH 7 and 10. Rates were strongly stimulated by the addition of the redox mediator 2,6-antraquinone disulfonate and by redox-active components in the fulvic-acid fraction of humus. Although the contribution of strain PeC11 to intestinal Fe(III) reduction in P. ephippiata remains to be further elucidated, our results corroborate the hypothesis that the lack of oxygen and the solubilization of humic substances in the extremely alkaline guts of humivorous soil fauna provide favorable conditions for the efficient reduction of Fe(III) and humic substances by a primarily fermentative microbiota. Copyright © 2012 Elsevier GmbH. All rights reserved.

Climatic, Edaphic Factors and Cropping History Help Predict Click Beetle (Coleoptera: Elateridae) (Agriotes spp.) Abundance.

PubMed

Kozina, A; Lemic, D; Bazok, R; Mikac, K M; Mclean, C M; Ivezić, M; Igrc Barčić, J

2015-01-01

It is assumed that the abundance of Agriotes wireworms (Coleoptera: Elateridae) is affected by agro-ecological factors such as climatic and edaphic factors and the crop/previous crop grown at the sites investigated. The aim of this study, conducted in three different geographic counties in Croatia from 2007 to 2009, was to determine the factors that influence the abundance of adult click beetle of the species Agriotes brevis Cand., Agriotes lineatus (L.), Agriotes obscurus (L.), Agriotes sputator (L.), and Agriotes ustulatus Schall. The mean annual air temperature, total rainfall, percentage of coarse and fine sand, coarse and fine silt and clay, the soil pH, and humus were investigated as potential factors that may influence abundance. Adult click beetle emergence was monitored using sex pheromone traps (YATLORf and VARb3). Exploratory data analysis was preformed via regression tree models and regional differences in Agriotes species' abundance were predicted based on the agro-ecological factors measured. It was found that the best overall predictor of A. brevis abundance was the previous crop grown. Conversely, the best predictor of A. lineatus abundance was the current crop being grown and the percentage of humus. The best predictor of A. obscurus abundance was soil pH in KCl. The best predictor of A. sputator abundance was rainfall. Finally, the best predictors of A. ustulatus abundance were soil pH in KCl and humus. These results may be useful in regional pest control programs or for predicting future outbreaks of these species. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Experimental investigation of convective stability in a superposed fluid and porous layer when heated from below

NASA Technical Reports Server (NTRS)

Chen, Falin; Chen, C. F.

1989-01-01

Experiments have been carried out in a horizontal superposed fluid and porous layer contained in a test box 24 cm x 12 cm x 4 cm high. The porous layer consisted of 3 mm diameter glass beads, and the fluids used were water, 60 and 90 percent glycerin-water solutions, and 100 percent glycerin. The depth ratio d, which is the ratio of the thickness of the fluid layer to that of the porous layer, varied from 0 to 1.0. Fluids of increasingly higher viscosity were used for cases with larger d in order to keep the temperature difference across the tank within reasonable limits. The size of the convection cells was inferred from temperature measurements made with embedded thermocouples and from temperature distributions at the top of the layer by use of liquid crystal film. The experimental results showed: (1) a precipitous decrease in the critical Rayleigh number as the depth of the fluid layer was increased from zero, and (2) an eightfold decrease in the critical wavelength between d = 0.1 and 0.2. Both of these results were predicted by the linear stability theory reported earlier (Chen and Chen, 1988).

Solid oxide fuel cells with bi-layered electrolyte structure

NASA Astrophysics Data System (ADS)

Zhang, Xinge; Robertson, Mark; Decès-Petit, Cyrille; Xie, Yongsong; Hui, Rob; Qu, Wei; Kesler, Olivera; Maric, Radenka; Ghosh, Dave

In this work, we have developed solid oxide fuel cells with a bi-layered electrolyte of 2 μm SSZ and 4 μm SDC using tape casting, screen printing, and co-firing processes. The cell reached power densities of 0.54 W cm -2 at 650 °C and 0.85 W cm -2 at 700 °C, with open circuit voltage (OCV) values larger than 1.02 V. The electrical leaking between anode and cathode through an SDC electrolyte has been blocked in the bi-layered electrolyte structure. However, both the electrolyte resistance (R el) and electrode polarization resistance (R p,a+c) increased in comparison to cells with single-layered SDC electrolytes. The formation of a solid solution of (Ce, Zr)O 2- x during sintering process and the flaws in the bi-layered electrolyte structure seem to be the main causes for the increase in the R el value (0.32 Ω cm 2) at 650 °C, which is almost one order of magnitude higher than the calculated value.

Atomic layer deposition of alternative glass microchannel plates

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Mahony, Aileen, E-mail: aom@incomusa.com; Craven, Christopher A.; Minot, Michael J.

The technique of atomic layer deposition (ALD) has enabled the development of alternative glass microchannel plates (MCPs) with independently tunable resistive and emissive layers, resulting in excellent thickness uniformity across the large area (20 × 20 cm), high aspect ratio (60:1 L/d) glass substrates. Furthermore, the use of ALD to deposit functional layers allows the optimal substrate material to be selected, such as borosilicate glass, which has many benefits compared to the lead-oxide glass used in conventional MCPs, including increased stability and lifetime, low background noise, mechanical robustness, and larger area (at present up to 400 cm{sup 2}). Resistively stable, high gain MCPs are demonstratedmore » due to the deposition of uniform ALD resistive and emissive layers on alternative glass microcapillary substrates. The MCP performance characteristics reported include increased stability and lifetime, low background noise (0.04 events cm{sup −2} s{sup −1}), and low gain variation (±5%)« less

Analysis of epitaxial drift field N on P silicon solar cells

NASA Technical Reports Server (NTRS)

Baraona, C. R.; Brandhorst, H. W., Jr.

1976-01-01

The performance of epitaxial drift field silicon solar cell structures having a variety of impurity profiles was calculated. These structures consist of a uniformly doped P-type substrate layer, and a P-type epitaxial drift field layer with a variety of field strengths. Several N-layer structures were modeled. A four layer solar cell model was used to calculate efficiency, open circuit voltage and short circuit current. The effect on performance of layer thickness, doping level, and diffusion length was determined. The results show that peak initial efficiency of 18.1% occurs for a drift field thickness of about 30 micron with the doping rising from 10 to the 17th power atoms/cu cm at the edge of the depletion region to 10 to the 18th power atoms/cu cm in the substrate. Stronger drift fields (narrow field regions) allowed very high performance (17% efficiency) even after irradiation to 3x10 to the 14th power 1 MeV electrons/sq cm.

Application Prospects of Multilayer Film Shields for Space Research Instrumentation

NASA Astrophysics Data System (ADS)

Nyunt, P. W.; Vlasik, K. F.; Grachev, V. M.; Dmitrenko, V. V.; Novikov, A. S.; Petrenko, D. V.; Ulin, S. E.; Uteshev, Z. M.; Chernysheva, I. V.; Shustov, A. E.

We have studied the magnetic properties of multilayer film cylindrical configuration shields (MFS) based on NiFe / Cu. The studied samples were prepared by electrode position. MFS were constituted by alternating layers of NiFe and Cu, deposited on an aluminum cylinder with diameter of 4 cm, length of 13 cm and 0.5 cm thickness. The thickness of each ferromagnetic layer varied from 10 to 150 μm, and the thickness of Cu layers was 5 μm. Five-samples in which the number of ferromagnetic layers varied from 3 to 45 and copper - from 2 to 44 were tested. The best shielding efficiency was achieved at the maximum number of layers and comprised about 102. Permalloy multilayer foil shield at the same total thickness has several times less efficiency in comparison with MFS. The description of a prototype of the charged particles telescope for space application is presented. Results of its testing regarding sensitivity to the constant magnetic field are described.

Impact of Mg-ion implantation with various fluence ranges on optical properties of n-type GaN

NASA Astrophysics Data System (ADS)

Tsuge, Hirofumi; Ikeda, Kiyoji; Kato, Shigeki; Nishimura, Tomoaki; Nakamura, Tohru; Kuriyama, Kazuo; Mishima, Tomoyoshi

2017-10-01

Optical characteristics of Mg-ion implanted GaN layers with various fluence ranges were evaluated. Mg ion implantation was performed twice at energies of 30 and 60 keV on n-GaN layers. The first implantation at 30 keV was performed with three different fluence ranges of 1.0 × 1014, 1.0 × 1015 and 5.0 × 1015 cm-2. The second implantation at an energy of 60 keV was performed with a fluence of 6.5 × 1013 cm-2. After implantation, samples were annealed at 1250 °C for 1 min under N2 atmosphere. Photoluminescence (PL) spectrum of the GaN layer with the Mg ion implantation at the fluence range of 1.0 × 1014 cm-2 at 30 keV was similar to the one of Mg-doped p-GaN layers grown by MOVPE (Metal-Organic Vapor Phase Epitaxy) on free-standing GaN substrates and those at the fluence ranges over 1.0 × 1015 cm-2 were largely degraded.

Performance tests for the NASA Ames Research Center 20 cm x 40 cm oscillating flow wind tunnel

NASA Technical Reports Server (NTRS)

Cook, W. J.; Giddings, T. A.

1984-01-01

An evaluation is presented of initial tests conducted to assess the performance of the NASA Ames 20 cm x 40 cm oscillating flow wind tunnel. The features of the tunnel are described and two aspects of tunnel operation are discussed. The first is an assessment of the steady mainstream and boundary layer flows and the second deals with oscillating mainstream and boundary layer flows. Experimental results indicate that in steady flow the test section mainstream velocity is uniform in the flow direction and in cross section. The freestream turbulence intensity is about 0.2 percent. With minor exceptions the steady turbulent boundary layer generated on the top wall of the test section exhibits the characteristics of a zero pressure gradient turbulent boundary layer generated on a flat plate. The tunnel was designed to generate sinusoidal oscillating mainstream flows. Experiments confirm that the tunnel produces sinusoidal mainstream velocity variations for the range of frequencies (up to 15 Hz). The results of this study demonstrate that the tunnel essentially produces the flows that it was designed to produce.

Polyhedral Serpentine Grains in CM Chondrites

NASA Technical Reports Server (NTRS)

Zega, Thomas J.; Garvie, Laurence A. J.; Dodony, Istvan; Stroud, Rhonda M.; Buseck, Peter R.

2005-01-01

CM chondrites are primitive rocks that experienced aqueous alteration in the early solar system. Their matrices and fine-grained rims (FGRs) sustained the effects of alteration, and the minerals within them hold clues to the aqueous reactions. Sheet silicates are an important product of alteration, and those of the serpentine group are abundant in the CM2 chondrites. Here we expand on our previous efforts to characterize the structure and chemistry of serpentines in CM chondrites and report results on a polyhedral form that is structurally similar to polygonal serpentine. Polygonal serpentine consists of tetrahedral (T) sheets joined to M(2+)-centered octahedral (O) sheets (where (M2+) is primarily Mg(2+) and Fe(2+)), which give rise to a 1:1 (TO) layered structure with a 0.7-nm layer periodicity. The structure is similar to chrysotile in that it consists of concentric lizardite layers wrapped around the fiber axis. However, unlike the rolled-up chrysotile, the tetrahedral sheets of the lizardite layers are periodically inverted and kinked, producing sectors. The relative angles between sectors result in 15- and 30-sided polygons in terrestrial samples.

Measurement of carbon for carbon sequestration and site monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Madhavi Z; Wullschleger, Stan D; Garten Jr, Charles T

A 2 to 6 degree C increase in global temperature by 2050 has been predicted due to the production of greenhouse gases that is directly linked to human activities. This has encouraged an increase in the international efforts on ways to reduce anthropogenic emissions of greenhouse gases particularly carbon dioxide (CO{sub 2}) as evidence for the link between atmospheric greenhouse gases and climate change has been established. Suggestion that soils and vegetation could be managed to increase their uptake and storage of CO{sub 2}, and thus become 'land carbon sinks' is an incentive for scientists to undertake the ability tomore » measure and quantify the carbon in soils and vegetation to establish base-line quantities present at this time. The verification of the permanence of these carbon sinks has raised some concern regarding the accuracy of their long-term existence. Out of the total percentage of carbon that is potentially sequestered in the terrestrial land mass, only 25% of that is sequestered above ground and almost 75% is hypothesized to be sequestered underground. Soil is composed of solids, liquids, and gases which is similar to a three-phase system. The gross chemical composition of soil organic carbon (SOC) consists of 65% humic substances that are amorphous, dark-colored, complex, polyelectrolyte-like materials that range in molecular weight from a few hundred to several thousand Daltons. The very complex structure of humic and fulvic acid makes it difficult to obtain a spectral signature for all soils in general. The humic acids of different soils have been observed to have polymeric structure, appearing as rings, chains and clusters as seen in electron microscope observations. The humification processes of the soils will decide the sizes of their macromolecules that range from 60-500 angstroms. The percentage of the humus that occurs in the light brown soils is much lower than the humus present in dark brown soils. The humus of forest soils is characterized by a high content of fulvic acids while the humus of peat and grassland soils is high in humic acids. Similarly it is well known that the amount of carbon present in forest soils is lower than the amount present in grassland soils.« less

Kinetics of Indigenous Nitrate Reducing Sulfide Oxidizing Activity in Microaerophilic Wastewater Biofilms

PubMed Central

Villahermosa, Desirée; Corzo, Alfonso; Garcia-Robledo, Emilio; González, Juan M.; Papaspyrou, Sokratis

2016-01-01

Nitrate decreases sulfide release in wastewater treatment plants (WWTP), but little is known on how it affects the microzonation and kinetics of related microbial processes within the biofilm. The effect of nitrate addition on these properties for sulfate reduction, sulfide oxidation, and oxygen respiration were studied with the use of microelectrodes in microaerophilic wastewater biofilms. Mass balance calaculations and community composition analysis were also performed. At basal WWTP conditions, the biofilm presented a double-layer system. The upper microaerophilic layer (~300 μm) showed low sulfide production (0.31 μmol cm-3 h-1) and oxygen consumption rates (0.01 μmol cm-3 h-1). The anoxic lower layer showed high sulfide production (2.7 μmol cm-3 h-1). Nitrate addition decreased net sulfide production rates, caused by an increase in sulfide oxidation rates (SOR) in the upper layer, rather than an inhibition of sulfate reducing bacteria (SRB). This suggests that the indigenous nitrate reducing-sulfide oxidizing bacteria (NR-SOB) were immediately activated by nitrate. The functional vertical structure of the biofilm changed to a triple-layer system, where the previously upper sulfide-producing layer in the absence of nitrate split into two new layers: 1) an upper sulfide-consuming layer, whose thickness is probably determined by the nitrate penetration depth within the biofilm, and 2) a middle layer producing sulfide at an even higher rate than in the absence of nitrate in some cases. Below these layers, the lower net sulfide-producing layer remained unaffected. Net SOR varied from 0.05 to 0.72 μmol cm-3 h-1 depending on nitrate and sulfate availability. Addition of low nitrate concentrations likely increased sulfate availability within the biofilm and resulted in an increase of both net sulfate reduction and net sulfide oxidation by overcoming sulfate diffusional limitation from the water phase and the strong coupling between SRB and NR-SOB syntrophic relationship. PMID:26872267

Vegetation cover of forest, shrub and pasture strongly influences soil bacterial community structure as revealed by 16S rRNA gene T-RFLP analysis.

PubMed

Chim Chan, On; Casper, Peter; Sha, Li Qing; Feng, Zhi Li; Fu, Yun; Yang, Xiao Dong; Ulrich, Andreas; Zou, Xiao Ming

2008-06-01

Bacterial community structure is influenced by vegetation, climate and soil chemical properties. To evaluate these influences, terminal restriction fragment length polymorphism (T-RFLP) and cloning of the 16S rRNA gene were used to analyze the soil bacterial communities in different ecosystems in southwestern China. We compared (1) broad-leaved forest, shrub and pastures in a high-plateau region, (2) three broad-leaved forests representing a climate gradient from high-plateau temperate to subtropical and tropical regions and (3) the humus and mineral soil layers of forests, shrub lands and pastures with open and restricted grazing activities, having varied soil carbon and nutrient contents. Principal component analysis of the T-RFLP patterns revealed that soil bacterial communities of the three vegetation types were distinct. The broad-leaved forests in different climates clustered together, and relatively minor differences were observed between the soil layers or the grazing regimes. Acidobacteria dominated the broad-leaved forests (comprising 62% of the total clone sequences), but exhibited lower relative abundances in the soils of shrub (31%) and pasture (23%). Betaproteobacteria was another dominant taxa of shrub land (31%), whereas Alpha- (19%) and Gammaproteobacteria (13%) and Bacteriodetes (16%) were major components of pasture. Vegetation exerted more pronounced influences than climate and soil chemical properties.

Influence of forest management on the changes of organic soil properties in border part of Kragle Mokradlo Peatland (Stolowe Mountains National Park, Poland)

NASA Astrophysics Data System (ADS)

Bogacz, A.; Roszkowicz, M.

2009-04-01

SUMMARY The aim of this work was to determine the properties of organic soils modified by man, muddy and fluvial process. Peat horizons were analyzed and classified by types - and species of peat. Three profiles of shallow peat and peaty gley soils identified. Investigation showed that organic soil developed on a sandy weathered sandstone base according to oligotrophic type of sites. Organic horizons were mixed with sand and separated by sandy layers. Those soils were classified as Sapric Histosols Dystric or Sapric Gleysols Histic (WRB 2006). The throphism of organic soil in this object resulted from both natural factors and anthropo-pedogenesis. key words: peat deposit, organic soils, soil properties, muddy process, sandy layers INTRODUCTION The areas of Stolowe Mountains National Park were influenced by forestry management. Many peatlands in the Park area were drained for forestry before World War II. Several amelioration attempts were undertaken as early as in the nineteenth century. The system of forest roads were built on drained areas. The Kragle Mokradlo Peatland is located in the Skalniak plateau. The object is cut by a melioration ditch. This ditch has been recently blocked to rewet the objects. Several forest roads pass in the close neighbourhood of investigated areas. In a border part of Kragle Mokradlo Peatlands, we can observe artificial spruce habitat. Investigated object represents shallow peat soil developed on sandy basement. The early investigations showed that peaty soils were also covered by sandstone - related deposits, several dozen centimeter thick (BOGACZ 2000). Those layers was developed from sandstone weathered material transported by wind and water. The aim of presented works was to determine the stage of evolution of organic soils on the base on their morphological, physical and chemical properties. MATERIAL AND METHODS Peat soils in different locations (3 profiles, 18 samples) were selected for examination. Peat samples were collected from study areas using a 6.0 cm diameter Instorfu peat auger (HORAWSKI 1987). Soil horizons were determined on the basis of colour, degree of organic matter decomposition and the quality of vegetation remains. Cores were taken to the depth where underlying mineral material was encountered. The cores ware sectioned to subsamples at intervals at major stratigrafic breaks. Some physical, chemical properties and botanical composition of peat were determined in this material. Differentiation in botanical composition of peat was analyzed by the microscopic method and subsequently classified according to the Polish standards (Oznaczanie gatunku...1977). Peat humification degree was measured using two methods: SPEC method and half syringe method (LYNN at all. 1974). Ash content was estimated by combusting the material in a muffle furnace at 500oC for 4 hours. The texture of mineral horizons was determined using the Bouyoucos hydrometer method (GEE AND BOUNDER 1986). The specific gravity (W) and bulk density (Z) of organic soils were calculated using the following formula's (ZAWADZKI 1970): W=0.11A+1.451, (1.451) represents the specific gravity of humus, Z =0.004A+0.0913, A is a ash content and constant (0.0913) represents the bulk density of humus. The following chemical properties of organic soil horizons were analyzed: content of total carbon and nitrogen, acidity in H2O and 1mol dm-3 KCl and CECe in CH3COONH4 at pH 7. Base saturation (BS) of soil sorption complex was calculated. The soils were classified to reference groups in WRB Classification System (WRB 2006). RESULTS AND DISSCUSION Based on the cores, -the soils in the border part of Kragle Mokradlo Peatland area were classified as Sapric Histosols Dystric or Sapric Gleysols Histic (WRB 2006). Soils represented ombrogenic type of hydrological conditions. In that site, an ombrogenic type of hydrological input is the predominant mechanism of soil evolution. Soil examined in this study have developed in oligotrophic type of site. Organic soils developed on sandy weathered sandstones. The depth of organic horizons ranged from 40 to 80 cm. The object represented spruce forests habitat introduced by man. Organic horizons were separated by sandy layers. The process of sandstone weathering and forestry management changed morphological features of soils. Presently, the area is under the influence of fluvigenic type of hydrological input, too. Geobotanical analyses of peat layers indicated significant presence of preserved fragments of roots grasses, Sphagnum sp. and Bryales sp. Hemic or sapric material were usually present in organic horizons of this object. Analysis of organic horizons showed that their specific gravity was about 1.58-2.25 g cm-3, the bulk density was 0.14-0.42 g cm-3. The total porosity was in the range 82.0-91.1% and the ash content: in the range 11.74-77.96% of soil dry matter. Organic material consisting of weathered sandstone was likely to move down the profiles, increasing the concentration of sand and silt fractions in organic horizons. The similar phenomenon of residual deposits was reported by KLEMENTOWSKI (1979). The values of bulk density of peatland soils are connected with the high ash content. Ash content was different in situated layers. This is caused by the muddy and fluvial process. This situation was influenced by trophical status of this soils. The pH of sand and peat layers in a border part of Krągłe Mokradło Peatland was strongly acidic: pH H2O 2.92-3.51, pH KCl 2.38-3.07. The acidity was lower in upper horizons than in deeper ones. The ratio C/N in organic horizons ranged between 10:1 to 40:1. Low ratios of C/N in some upper horizons were probably caused by strong mineralization of organic matter. Strongly acidic soil horizons usually exhibited high cation exchange capacity (CECe). In general, the base saturated (BS) did not exceed 50%. Organic surface horizons showed higher content of potassium, calcium and magnesium than lower horizons. CONCLUSIONS Shallow organic soils occupy the ombrotrophic sites of a border part of Kragle Mokradlo Peatland. The variety of organic soil throphism in the object resulted from the placement on the base sandstone, partial mixing of soil horizons as well as from muddy and fluvial processes. Peat horizons present in the studied profiles were generally classified as hemic and sapric, sometimes as fibric. Soil horizons exhibited differed thickness and ash content. Forest management strongly changed the properties of organic soil. REFERENCES Bogacz, A. (2000). Physical properties of organic soil in Stolowe Mountains National Park (Poland). Suo 51,3; pp.105-113. Gee, G.W. and Bauder, J.W. (1986). Particle-size analysis. In: Klute, A.(ed.) Methods of Soil Analysis Part I. Agronomy series No. 9. Am. Soc. Agronomy Soil Sci. Am, Inc., Publ., Madison, WI.pp. 383-411. Horawski, M. (1987). Torfoznawstwo dla meliorantow. Pojecia podstawowe.[Peat science for melioration. Basic definitions.]. Wydawnictwo Akademii Rolniczej w Krakowie. pp.37-39.[In Polish]. Lubliner - Mianowska, K. (1951). Wskazowki do badania torfu. Metody geobotaniczne, polowe i laboratoryjne [Hints to peat research. In: Geobotanical, field and laboratory methods] Państwowe Wydawnictwo Techniczne, Katowice.pp.58-60. [In Polish]. Lynn, W.C., Mc Kinzie, W.E., Grossman, R.B. (1974). Field Laboratory Test for characterization of Histosols. In: Histosols, their characteristics, classification and use. pp. 11-20. Oznaczanie gatunku, rodzaju i typu torfu. (1977). [Peat and peat varies. Determination of classes, sort and types of peat]. Polish standard PN-76/G-02501, [Polish Normalization Commitee]. pp.1-11.[In Polish]. Word Reference Base for Soil Resources. 1998. Word Soil Resources Report, 84. FAO-ISRIC-ISSS, Rome, pp.1-88. Zawadzki, S. (1970). Relationship between the content of organic matter and physical properties of hydrogenic soils. Polish Journal of Soil Science Vol.III, 1; pp.3-9.

Significantly Elevated Dielectric and Energy Storage Traits in Boron Nitride Filled Polymer Nano-composites with Topological Structure

NASA Astrophysics Data System (ADS)

Feng, Yefeng; Zhang, Jianxiong; Hu, Jianbing; Li, Shichun; Peng, Cheng

2018-03-01

Interface induced polarization has a prominent influence on dielectric properties of 0-3 type polymer based composites containing Si-based semi-conductors. The disadvantages of composites were higher dielectric loss, lower breakdown strength and energy storage density, although higher permittivity was achieved. In this work, dielectric, conductive, breakdown and energy storage properties of four nano-composites have been researched. Based on the cooperation of fluoropolymer/alpha-SiC layer and fluoropolymer/hexagonal-BN layer, it was confirmed constructing the heterogeneous layer-by-layer composite structure rather than homogeneous mono-layer structure could significantly reduce dielectric loss, promote breakdown strength and increase energy storage density. The former worked for a larger dielectric response and the latter layer acted as a robust barrier of charge carrier transfer. The best nano-composite could possess a permittivity of 43@100 Hz ( 3.3 times of polymer), loss of 0.07@100 Hz ( 37% of polymer), discharged energy density of 2.23 J/cm3@249 kV/cm ( 10 times of polymer) and discharged energy efficiency of 54%@249 kV/cm ( 5 times of polymer). This work might enlighten a facile route to achieve the promising high energy storage composite dielectrics by constructing the layer-by-layer topological structure.

Estimating active layer thickness and volumetric water content from ground penetrating radar measurements in Barrow, Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jafarov, E. E.; Parsekian, A. D.; Schaefer, K.

Ground penetrating radar (GPR) has emerged as an effective tool for estimating active layer thickness (ALT) and volumetric water content (VWC) within the active layer. In August 2013, we conducted a series of GPR and probing surveys using a 500 MHz antenna and metallic probe around Barrow, Alaska. Here, we collected about 15 km of GPR data and 1.5 km of probing data. We describe the GPR data processing workflow from raw GPR data to the estimated ALT and VWC. We then include the corresponding uncertainties for each measured and estimated parameter. The estimated average GPR-derived ALT was 41 cm,more » with a standard deviation of 9 cm. The average probed ALT was 40 cm, with a standard deviation of 12 cm. The average GPR-derived VWC was 0.65, with a standard deviation of 0.14.« less

Estimating active layer thickness and volumetric water content from ground penetrating radar measurements in Barrow, Alaska

DOE PAGES

Jafarov, E. E.; Parsekian, A. D.; Schaefer, K.; ...

2018-01-09

Ground penetrating radar (GPR) has emerged as an effective tool for estimating active layer thickness (ALT) and volumetric water content (VWC) within the active layer. In August 2013, we conducted a series of GPR and probing surveys using a 500 MHz antenna and metallic probe around Barrow, Alaska. Here, we collected about 15 km of GPR data and 1.5 km of probing data. We describe the GPR data processing workflow from raw GPR data to the estimated ALT and VWC. We then include the corresponding uncertainties for each measured and estimated parameter. The estimated average GPR-derived ALT was 41 cm,more » with a standard deviation of 9 cm. The average probed ALT was 40 cm, with a standard deviation of 12 cm. The average GPR-derived VWC was 0.65, with a standard deviation of 0.14.« less

Heavily doped GaAs:Te layers grown by MOVPE using diisopropyl telluride as a source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daniltsev, V. M.; Demidov, E. V.; Drozdov, M. N.

2016-11-15

The capabilities of GaAs epitaxial layers extremely heavily doped with tellurium by metal-organic vapor-phase epitaxy using diisopropyl telluride as a source are studied. It is shown that tellurium incorporation into GaAs occurs to an atomic concentration of 10{sup 21} cm{sup –3} without appreciable diffusion and segregation effects. Good carrier concentrations (2 × 10{sup 19} cm{sup –3}) and specific contact resistances of non-alloyed ohmic contacts (1.7 × 10{sup –6} Ω cm{sup 2}) give grounds to use such layers to create non-alloyed ohmic contacts in electronic devices. A sharp decrease in the electrical activity of Te atoms, a decrease in the electronmore » mobility, and an increase in the contact resistance at atomic concentrations above 2 × 10{sup 20} cm{sup –3} are detected.« less

Compost quality and its function as a soil conditioner of recultivation layers - a critical review

NASA Astrophysics Data System (ADS)

Beck-Broichsitter, Steffen; Fleige, Heiner; Horn, Rainer

2018-01-01

During a period of 4 years, soil chemical and physical properties of the temporary capping system in Rastorf (Northern Germany) were estimated, whereby compost was partly used as soil improver in the upper recultivation layer. The air capacity and the available water capacity of soil samples were first determined in 2013 (without compost), and then in 2015 (with compost) under laboratory conditions. Herein, the addition of compost had a positive effect on: the air capacity up to 13.4 cm3 cm-3; and the available water capacity up to 20.1 cm3 cm-3 in 2015, in the recultivation layer (0-20 cm). However, taking into account the in situ results of the tensiometer and frequency domain reflectometry measurements, the addition of compost had a negative effect. The soil-compost mixture led to restricted remoistening even after a normal summer drying period in autumn and induced more negative matric potentials in the recultivation layer. In summary, the soil-improving effect of the compost addition, in conjunction with an increased water storage capacity, is undeniable and was demonstrated in a combined field and laboratory study. Therefore, intensive hydrophobicity can inhibit the homogeneous remoistening of the soil, resulting in a decreased hydraulic effectiveness of the sealing system.

The increase of the fertility of soils using the liquid organic fertilizers and fertilizers based on sugar-beet wastes.

NASA Astrophysics Data System (ADS)

Vyborova, Oxana

2010-05-01

The fertility of soil is a capacity for ensuring plants by water, nutrients, air and capacity for making optimal conditions for growth and development of plants. The result of it is a yield. The main characteristic of fertility of soil is maintenance of humus. The humus is important part of organic matter. The supporting of soil fertility is impossible by traditional methods. The amount of receiving mineral fertilizers in agriculture will not increase in future, because mineral fertilizers are very expensive. The mineral fertilizers don't influence on maintenance of total amount of humus in soil and improve the circulation of nutrients. Every hectare of fields have to receive no less than 8-10 tons of organic fertilizers, therefore we will have self-supporting balance of humus and the fertility of soils will be increasing. Consequently we are looking for new types of organic materials and we include them in modern agro technologies. One of them is an organomineral fertilizer (lignitic materials). The humic chemicals in the form of lignitic materials of natrium, potassium and ammonium are permitted for using them in agriculture at the beginning of 1984. The Department of agriculture in Russian Federation considered the problem of using humic chemicals and made a decision to use them on the fields of our country, because the lignitic materials can restore the fertility of our fields. The lignitic materials increase the amount of spore-forming bacteria, mold fungi and actinomycete. Therefore the organic decomposition occurs more strongly, the processes of humification increase the speed and the amount of humus rises in the soil. The new forming humus has a high biological activity and it improves chemical and physical soil properties. The addition of lignitic materials in soil activates different groups of microorganisms, which influence on mobilization of nutrients and transformation from potential to effective fertility. The inclusion of humic fertilizers improves physical, physicochemical properties of soils, its air, water and thermal rate. Humic acids with mineral and organomineral particles of soil form the soil absorbent complex. The inclusion of humic fertilizers promotes the process when humic substances form a very valuable water-stable clumpy-granular structure, which improves water-carrying and water-holding capacity, its air permeability by agglutination of mineral particles with each other. The soils, where humic fertilizers are carried in soils regularly, are more stable for influence of chemical polluting substances (for example, radioactive nuclides, heavy metals, pesticides) than poor soils. The inclusion of humic fertilizers is very important in period of urbanization and cropping on the plough-lands not far from a big industrial area. The lignitic materials tie together the detrimental compounds formed the insoluble complex in soil solution. The detrimental compounds don't go into plants, subsoil waters and atmosphere. The lignitic watering of soils (in concentration from 0.1 to 0.01%) increases biological activity of soil in a man-caused zones and it promotes to stability of plants to detrimental emission of enterprises. Today the problem of processing of sugar-beet industry is very important. In the result of storing sugar-beet wastes the pollution of environment is occurred, examples of this pollution are gassing, salinization of soils and ground waters by filtrational sediments. One of these wastes is defecation sludge. The defecation sludge consists of CaCO3, organic matter, nitrogen, phosphorus, potassium and microelements. The technology of receiving N-Ca fertilizer based on defecate was developed because of impossibility of using this waste in pure form. For available data, using of these fertilizers improves the soil fertility and degree of pollution by heavy metals don't exceed an acceptance limits.

Active layer and permafrost thermal regime in a patterned ground soil in Maritime Antarctica, and relationship with climate variability models.

PubMed

Chaves, D A; Lyra, G B; Francelino, M R; Silva, Ldb; Thomazini, A; Schaefer, Cegr

2017-04-15

Permafrost and active layer studies are important to understand and predict regional climate changes. The objectives of this work were: i) to characterize the soil thermal regime (active layer thickness and permafrost formation) and its interannual variability and ii) to evaluate the influence of different climate variability modes to the observed soil thermal regime in a patterned ground soil in Maritime Antarctica. The study was carried out at Keller Peninsula, King George Island, Maritime Antarctica. Six soil temperatures probes were installed at different depths (10, 30 and 80cm) in the polygon center (Tc) and border (Tb) of a patterned ground soil. We applied cross-correlation analysis and standardized series were related to the Antarctic Oscillation Index (AAO). The estimated active layer thickness was approximately 0.75cm in the polygon border and 0.64cm in the center, indicating the presence of permafrost (within 80cm). Results indicate that summer and winter temperatures are becoming colder and warmer, respectively. Considering similar active layer thickness, the polygon border presented greater thawing days, resulting in greater vulnerability to warming, cooling faster than the center, due to its lower volumetric heat capacity (Cs). Cross-correlation analysis indicated statistically significant delay of 1day (at 10cm depth) in the polygon center, and 5days (at 80cm depth) for the thermal response between atmosphere and soil. Air temperature showed a delay of 5months with the climate variability models. The influence of southern winds from high latitudes, in the south facing slopes, favored freeze in the upper soil layers, and also contributed to keep permafrost closer to the surface. The observed cooling trend is linked to the regional climate variability modes influenced by atmospheric circulation, although longer monitoring period is required to reach a more precise scenario. Copyright © 2017 Elsevier B.V. All rights reserved.

The Influence of Heat Treatment on the Electrical Characteristics of Semi-Insulating SiC Layers Obtained by Irradiating n-SiC with High-Energy Argon Ions

NASA Astrophysics Data System (ADS)

Ivanov, P. A.; Potapov, A. S.; Kudoyarov, M. F.; Kozlovskii, M. A.; Samsonova, T. P.

2018-03-01

Irradiation of crystalline n-type silicon carbide ( n-SiC) with high-energy (53-MeV) argon ions was used to create near-surface semi-insulating ( i-SiC) layers. The influence of subsequent heat treatment on the electrical characteristics of i-SiC layers has been studied. The most high-ohmic ion-irradiated i-SiC layers with room-temperature resistivity of no less than 1.6 × 1013 Ω cm were obtained upon the heat treatment at 600°C, whereas the resistivity of such layers heat-treated at 230°C was about 5 × 107 Ω cm.

Development of an Anti-Corrosion Conductive Nano Carbon Coating Layer on Metal Bipolar Plates.

PubMed

Yeo, Kiho; Kim, Juyong; Kim, Jongryoul

2018-09-01

For automotive applications of polymer electrolyte membrane fuel cells, the enhancement of the corrosion resistance of metal bipolar plates has been a critical issue with regard to the lifespan of fuel cell stacks. In this paper, we present a novel method for increasing the lifespan by means of a conductive carbon coating on bipolar plates. Conductive carbon films were plasma coated onto metal bipolar plates in a vacuum at various temperatures. As a result, 316L stainless plates with a 10-nm-thick carbon coating layer on a 20-nm-thick CrN undercoat layer showed-contact resistance of 10.71 mΩcm2@10 kgf/cm2 and a corrosion current of 0.5 μA/cm2@0.6 V. This thin coating layer with high conductivity and excellent corrosion resistance suggests a new, effective coating method for the mass production of metal bipolar plates.

Process for growing epitaxial gallium nitride and composite wafers

DOEpatents

Weber, Eicke R.; Subramanya, Sudhir G.; Kim, Yihwan; Kruger, Joachim

2003-05-13

A novel growth procedure to grow epitaxial Group III metal nitride thin films on lattice-mismatched substrates is proposed. Demonstrated are the quality improvement of epitaxial GaN layers using a pure metallic Ga buffer layer on c-plane sapphire substrate. X-ray rocking curve results indicate that the layers had excellent structural properties. The electron Hall mobility increases to an outstandingly high value of .mu.>400 cm.sup.2 /Vs for an electron background concentration of 4.times.10.sup.17 cm.sup.-3.

An isotopic investigation of the temperature response of young and old soil organic matter respiration

NASA Astrophysics Data System (ADS)

Burns, Nancy; Cloy, Joanna; Garnett, Mark; Reay, David; Smith, Keith; Otten, Wilfred

2010-05-01

The effect of temperature on rates of soil respiration is critical to our understanding of the terrestrial carbon cycle and potential feedbacks to climate change. The relative temperature sensitivity of labile and recalcitrant soil organic matter (SOM) is still controversial; different studies have produced contrasting results, indicating limited understanding of the underlying relationships between stabilisation processes and temperature. Current global carbon cycle models still rely on the assumption that SOM pools with different decay rates have the same temperature response, yet small differences in temperature response between pools could lead to very different climate feedbacks. This study examined the temperature response of soil respiration and the age of soil carbon respired from radiocarbon dated fractions of SOM (free, intra-aggregate and mineral-bound) and whole soils (organic and mineral layers). Samples were collected from a peaty gley soil from Harwood Forest, Northumberland, UK. SOM fractions were isolated from organic layer (5 - 17 cm) material using high density flotation and ultrasonic disaggregation - designated as free (< 1.8 g cm-3), intra-aggregate (< 1.8 g cm-3 within aggregates > 1.8 g cm-3) and mineral-bound (> 1.8 g cm-3) SOM. Fractions were analysed for chemical composition (FTIR, CHN analysis, ICP-OES), 14C (AMS), δ13C and δ15N (MS) and thermal properties (DSC). SOM fractions and bulk soil from the organic layer and the mineral layer (20 - 30 cm) were incubated in sealed vessels at 30 ° C and 10 ° C for 3 or 9 months to allow accumulation of CO2 sufficient for sampling. Accumulated respired CO2 samples were collected on zeolite molecular sieve cartridges and used for AMS radiocarbon dating. In parallel, material from the same fractions and layers were incubated at 10 ° C, 15 ° C, 25 ° C and 30 ° C for 6 months and sampled weekly for CO2 flux measurements using GC chromatography. Initial data have shown radiocarbon ages ranging from modern to 219 y BP in bulk soil from the organic layer (5 - 17 cm depth), while free OM ranged from modern to 74 y BP, intra-aggregate OM 413 - 657 y BP and mineral-bound material 562 - 646 y BP. Bulk soil from the mineral layer (20 - 30 cm) was considerably older, at 2142 - 2216 y BP. These results indicate that within the upper layer of soil, mineral-bound OM represents a slow-cycling or recalcitrant pool of SOM; intra-aggregate OM is slightly less recalcitrant than mineral-bound OM, while free OM represents a fast-cycling, labile pool of SOM. Bulk soil from the mineral layer (20 - 30 cm) is much older than mineral-bound OM in the upper layers, suggesting the involvement of other stabilising factors associated with depth besides mineral interactions. The link between age and recalcitrance is corroborated by measured CO2 flux rates, which increase with decreasing age of fractions. Results for the 14C contents and calculated ages of isolated SOM fractions, bulk organic and mineral soils and their respired CO2 at different temperatures will be discussed and compared with long term trends in soil/SOM fraction CO2 fluxes and their temperature sensitivity. Data on soil chemical characteristics and δ13C values will also be presented.

The biochemical changes in hippocampal formation occurring in normal and seizure experiencing rats as a result of a ketogenic diet.

PubMed

Chwiej, Joanna; Skoczen, Agnieszka; Janeczko, Krzysztof; Kutorasinska, Justyna; Matusiak, Katarzyna; Figiel, Henryk; Dumas, Paul; Sandt, Christophe; Setkowicz, Zuzanna

2015-04-07

In this study, ketogenic diet-induced biochemical changes occurring in normal and epileptic hippocampal formations were compared. Four groups of rats were analyzed, namely seizure experiencing animals and normal rats previously fed with ketogenic (KSE and K groups respectively) or standard laboratory diet (NSE and N groups respectively). Synchrotron radiation based Fourier-transform infrared microspectroscopy was used for the analysis of distributions of the main organic components (proteins, lipids, compounds containing phosphate group(s)) and their structural modifications as well as anomalies in creatine accumulation with micrometer spatial resolution. Infrared spectra recorded in the molecular layers of the dentate gyrus (DG) areas of normal rats on a ketogenic diet (K) presented increased intensity of the 1740 cm(-1) absorption band. This originates from the stretching vibrations of carbonyl groups and probably reflects increased accumulation of ketone bodies occurring in animals on a high fat diet compared to those fed with a standard laboratory diet (N). The comparison of K and N groups showed, moreover, elevated ratios of absorbance at 1634 and 1658 cm(-1) for DG internal layers and increased accumulation of creatine deposits in sector 3 of the Ammon's horn (CA3) hippocampal area of ketogenic diet fed rats. In multiform and internal layers of CA3, seizure experiencing animals on ketogenic diet (KSE) presented a lower ratio of absorbance at 1634 and 1658 cm(-1) compared to rats on standard laboratory diet (NSE). Moreover, in some of the examined cellular layers, the increased intensity of the 2924 cm(-1) lipid band as well as the massifs of 2800-3000 cm(-1) and 1360-1480 cm(-1), was found in KSE compared to NSE animals. The intensity of the 1740 cm(-1) band was diminished in DG molecular layers of KSE rats. The ketogenic diet did not modify the seizure induced anomalies in the unsaturation level of lipids or the number of creatine deposits.

Maggots as a wound debridement agent for chronic venous leg ulcers under graduated compression bandages: A randomised controlled trial.

PubMed

Davies, C E; Woolfrey, G; Hogg, N; Dyer, J; Cooper, A; Waldron, J; Bulbulia, R; Whyman, M R; Poskitt, K R

2015-12-01

Slough in chronic venous leg ulcers may be associated with delayed healing. The purpose of this study was to assess larval debridement in chronic venous leg ulcers and to assess subsequent effect on healing. All patients with chronic leg ulcers presenting to the leg ulcer service were evaluated for the study. Exclusion criteria were: ankle brachial pressure indices <0.85 or >1.25, no venous reflux on duplex and <20% of ulcer surface covered with slough. Participants were randomly allocated to either 4-layer compression bandaging alone or 4-layer compression bandaging + larvae. Surface areas of ulcer and slough were assessed on day 4; 4-layer compression bandaging was then continued and ulcer size was measured every 2 weeks for up to 12 weeks. A total of 601 patients with chronic leg ulcers were screened between November 2008 and July 2012. Of these, 20 were randomised to 4-layer compression bandaging and 20 to 4-layer compression bandaging + larvae. Median (range) ulcer size was 10.8 (3-21.3) cm(2) and 8.1 (4.3-13.5) cm(2) in the 4-layer compression bandaging and 4-layer compression bandaging + larvae groups, respectively (Mann-Whitney U test, P = 0.184). On day 4, median reduction in slough area was 3.7 cm(2) in the 4-layer compression bandaging group (P < 0.05) and 4.2 cm(2) (P < 0.001) in the 4-layer compression bandaging + larvae group. Median percentage area reduction of slough was 50% in the 4-layer compression bandaging group and 84% in the 4-layer compression bandaging + larvae group (Mann-Whitney U test, P < 0.05). The 12-week healing rate was 73% and 68% in the 4-layer compression bandaging and 4-layer compression bandaging + larvae groups, respectively (Kaplan-Meier analysis, P = 0.664). Larval debridement therapy improves wound debridement in chronic venous leg ulcers treated with multilayer compression bandages. However, no subsequent improvement in ulcer healing was demonstrated. © The Author(s) 2014.

High surface stability of magnetite on bi-layer Fe3O4/Fe/MgO(0 0 1) films under 1 MeV Kr+ ion irradiation

NASA Astrophysics Data System (ADS)

Kim-Ngan, N.-T. H.; Krupska, M.; Balogh, A. G.; Malinsky, P.; Mackova, A.

2017-12-01

We investigate the stability of the bi-layer Fe3O4/Fe(0 0 1) films grown epitaxially on MgO(0 0 1) substrates with the layer thickness in the range of 25-100 nm upon 1 MeV Kr+ ion irradiation. The layer structure and layer composition of the films before and after ion irradiation were studied by XRR, RBS and RBS-C techniques. The interdiffusion and intermixing was analyzed. No visible change in the RBS spectra was observed upon irradiation with ion fluence below 1015 Kr cm-2. The bi-layer structure and the stoichiometric Fe3O4 layer on the surface were well preserved after Kr+ ion irradiation at low damage levels, although the strong intermixing implied a large interfacial (Fe x O y ) and (Fe, Mg)O y layer respective at Fe3O4-Fe and Fe-MgO interface. The high ion fluence of 3.8  ×  1016 Kr cm-2 has induced a complete oxidization of the buffer Fe layer. Under such Kr fluence, the stoichiometry of the Fe3O4 surface layer was still preserved indicating its high stability. The entire film contains Fe x O y -type composition at ion fluence large than 5.0  ×  1016 Kr cm-2.

[Effects of short-term deep vertically rotary tillage on topsoil structure of lime concretion black soil and wheat growth in Huang-Huai-Hai Plain, China].

PubMed

Zhai, Zhen; Li, Yu Yi; Zhang, Li; Pang, Bo; Pang, Huan Cheng; Wei, Ben Hui; Wang, Qing Wei; Qi, Shao Wei

2017-04-18

Annual rotary tillage can often create a compacted plough pan and shallow arable layer which hampers the high crop yield in Huang-Huai-Hai region. A brand new farming method named Vertically Rotary Tillage was introduced to solve this problem. One short-term field experiment was conducted to explore the effect of deep vertically rotary tillage on soil physical properties and photosynthetic characteristics at flowering stage of winter wheat. Two tillage treatments were designed including subsoiling tillage with 20 cm depth (SS 20 , CK) and deep vertically rotary tillage with 30 cm depth (DVR 30 ). The result showed that compared with SS 20 treatment, DVR 30 treatment could thoroughly break the plow pan and loose the arable layer. The soil bulk density at 10-20 cm and 20-30 cm layers under DVR 30 treatment was decreased by 9.5% and 11.2% respectively than that under SS 20 treatment. Meanwhile, the penetration resistance at 20-30 cm layer under DVR 30 treatment was also decreased by 42.3% than that under SS 20 treatment. Moreover, water infiltration under DVR 30 treatment and the soil water storage in the deep soil layers was then increased. The mass water content of soil increased significantly with the increase of soil depth. There was significant difference of mass water content of 30-40 cm 40-50 cm between SS 20 and DVR 30 . The mass water content 30-40 cm and 40-50 cm layers under DVR 30 treatment was increased by 16.9% and 10.6% compared with SS 20 treatment, respectively. Furthermore, DVR 30 treatment promoted the improvement of the photosynthetic capacity of wheat which could contribute to the dry matter accumulation of winter wheat. The net photosynthesis rate and SPAD at flowering stage of winter wheat leaves under DVR 30 treatment were increased by 1.3% and 15.5% respectively than that under SS 20 treatment, thereby the above and underground dry matter accumulation of winter wheat under DVR 30 was increased significantly. Due to all the superiority of DVR 30 treatment over SS 20 treatment showed above, the winter wheat yield under DVR 30 treatment was increased by 12.4% than that under SS 20 . It was concluded that deep vertically rotary tillage could provide a new and effective way to break up the compacted plough pan, build a reasonable soil structure and increase crop yield.

[Water utilization characteristics of the degraded poplar shelterbelts in Zhangbei, Hebei, China.

PubMed

Zhang, Huan; Cao, Jun; Wang, Hua Bing; Song, Bo; Jia, Guo Dong; Liu, Zi Qiang; Yu, Xin Xiao; Zeng, Jia

2018-05-01

In Zhangbei County, Hebei Province, poplar-dominated shelterbelts are degraded to different extents. Water availability is the main limiting factor for plant survival in arid areas. The purpose of this study was to reveal the relationship between water availability and poplar degradation. Based on the hydrogen and oxygen stable isotope techniques, we explored the water sources of Populus simonii under different degradation degrees by comparing the isotopic values of P. simonii xylem water with that in potential water source, and calculated the utilization ratio of each water source. The results showed that the water sources of poplar trees varied with degradation degree. The water sources of P. simonii gradually transferred from the deep layer to the surface layer with the increases of degradation. P. simonii with no degradation mainly absorbed soil water in the range of 320-400 cm, with the utilization rate being 25.1%. P. simonii with slight degradation mainly used soil water at depth of 120-180, 180-240 and 240-320 cm. The total utilization rate of three layers was close to 50.0%, with less utilization of water from other layers. The moderately degraded P. simonii mainly used soil water at depth of 20-40, 40-60 and 60-80 cm. The utilization rate of each layer was 17.5%-20.9%, and the contribution rate of soil water under 120 cm was less than 10.0%. The severely degraded P. simonii mainly used water from surface soil layer (0-20 cm), with the utilization rate being 30.4%, which was significantly higher than that of other water sources. The water sources of poplar shelter forests were gradually shallower during the process of degradation. However, the low soil water content in the shallow layer could not meet the normal water demand of poplar, which would accelerate the degradation and even decline of poplar.

Soil thermal properties at two different sites on James Ross Island in the period 2012/13

NASA Astrophysics Data System (ADS)

Hrbáček, Filip; Láska, Kamil

2015-04-01

James Ross Island (JRI) is the largest island in the eastern part of the Antarctic Peninsula. Ulu Peninsula in the northern part of JRI is considered the largest ice free area in the Maritime Antarctica region. However, information about permafrost on JRI, active layer and its soil properties in general are poorly known. In this study, results of soil thermal measurements at two different sites on Ulu Peninsula are presented between 1 April 2012 and 30 April 2013. The study sites are located (1) on an old Holocene marine terrace (10 m a. s. l.) in the closest vicinity of Johann Gregor Mendel (JGM) Station and (2) on top of a volcanic plateau named Johnson Mesa (340 m a. s. l.) about 4 km south of the JGM Station. The soil temperatures were measured at 30 min interval using platinum resistance thermometers Pt100/8 in two profiles up to 200 cm at JGM Station and 75 cm at Johnson Mesa respectively. Decagon 10HS volumetric water content sensors were installed up 30 cm at Johnson Mesa to 50 cm at JGM Station, while Hukseflux HFP01 soil heat flux sensors were used for direct monitoring of soil physical properties at 2.5 cm depth at both sites. The mean soil temperature varied between -5.7°C at 50 cm and -6.3°C at 5 cm at JGM Station, while that for Johnson Mesa varied between -6.9°C at 50 cm and -7.1°C at 10 cm. Maximum active layer thickness estimated from 0 °C isotherm reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively which corresponded with maximum observed annual temperature at 50 cm at both sites. The warmest part of both profiles detected at 50 cm depth corresponded with maximum thickness of active layer, estimated from 0°C isotherm, reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively. Volumetric water content at 5 cm varied around 0.25 m3m-3 at both sites. The slight increase to 0.32 m3m-3 was observed at JGM Station at 50 cm and at Johnson Mesa at 30 cm depth. Soil texture analysis showed distinctly higher share of coarser fraction >2 mm at Johnson Mesa than at JGM Station. Comparison of both sites indicated that mean ground temperature at 50 cm depth was higher by 1.2 °C at JGM station, although the active layer was thicker by 2 cm only. It can therefore be concluded that soil physical properties like texture and moisture may significantly affect thermal regime at boundary between AL and permafrost table during individual thawing seasons.

The formation and potential importance of cemented layers in inactive sulfide mine tailings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blowes, D.W.; Reardon, E.J.; Cherry, J.A.

Investigations of inactive sulfide-rich tailings impoundments at the Heath Steele (New Brunswick) and Waite Amulet (Quebec) minesites have revealed two distinct types of cemented layers or hardpans. That at Heath Steele is 10-15 cm thick, occurs 20-30 cm below the depth of active oxidation, is continuous throughout the tailings impoundment, and is characterized by cementation of tailings by gypsum and Fe(II) solid phases, principally melanterite. Hardpan at the Waite Amulet site is only 1-5 cm thick, is laterally discontinuous (10-100 cm), occurs at the depth of active oxidation, and is characterized by cementation of tailings by Fe(III) minerals, principally goethite,more » lepidocrocite, ferrihydrite, and jarosite. At Heath Steele, an accumulation of gas-phase CO{sub 2}, of up to 60{percent} of the pore gas, occurs below the hardpan. The calculated diffusivity of the hardpan layer is only about 1/100 that of the overlying, uncemented tailings. The pore-water chemistry at Heath Steele has changed little over a 10-year period, suggesting that the cemented layer restricts the movement of dissolved metals through the tailings and also acts as a zone of metal accumulation. Generation of a cemented layer therefore has significant environmental and economic implications. It is likely that, in sulfide-rich tailings impoundments, the addition of carbonate-rich buffering material during the late stages of tailings deposition would enhance the formation of hardpan layers.« less

Substrate Structures For Growth Of Highly Oriented And/Or Epitaxial Layers Thereon

DOEpatents

Arendt, Paul N.; Foltyn, Stephen R.; Groves, James R.; Jia, Quanxi

2005-07-26

A composite substrate structure including a substrate, a layer of a crystalline metal oxide or crystalline metal oxynitride material upon the substrate, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the crystalline metal oxide or crystalline metal oxynitride material layer is provided together with additional layers such as one or more layers of a buffer material upon the oriented cubic oxide material layer. Jc's of 2.3×106 A/cm2 have been demonstrated with projected Ic's of 320 Amperes across a sample 1 cm wide for a superconducting article including a flexible polycrystalline metallic substrate, an inert oxide material layer upon the surface of the flexible polycrystalline metallic substrate, a layer of a crystalline metal oxide or crystalline metal oxynitride material upon the layer of the inert oxide material, a layer of an oriented cubic oxide material having a rock-salt-like structure upon the crystalline metal oxide or crystalline metal oxynitride material layer, a layer of a buffer material upon the oriented cubic oxide material layer, and, a top-layer of a high temperature superconducting material upon the layer of a buffer material.

Biogenic nitric oxide emission from a spruce forest soil in mountainous terrain

NASA Astrophysics Data System (ADS)

Falge, Eva; Bargsten, Anika; Behrendt, Thomas; Meixner, Franz X.

2010-05-01

The process-based spatial simulation model SVAT-CN was used to estimate biogenic nitric oxide (NO) emission by soils of a Norway spruce forest (Weidenbrunnen) in the Fichtelgebirge, Germany. SVAT-CN core is a combination of a multiple-layer soil water balance model and a multi-layered canopy gas exchange model. The soil modules comprise a flexible hybrid between a layered bucket model and classical basic liquid flow theory. Further soil processes include: heat transport, distribution of transpiration demand proportionally to soil resistance, reduction of leaf physiological parameters with limiting soil moisture. Spruce forest soils usually are characterized by a thick organic layer (raw humus), with the topmost centimetres being the location where most of the biogenic NO is produced. Within individual spruce forest stands the understory might be composed of patches characterized by different species (e.g. Vaccinium myrtillus, Picea abies, Deschampsia caespitosa), and NO production potentials. The effect of soil physical and chemical parameters and understory types on NO emission from the organic layer was investigated in laboratory incubation and fumigation experiments on soils sampled below the various understory covers found at the Weidenbrunnen site. Results from the laboratory experiments were used to parameterize multi-factorial regression models of soil NO emission with respect to its response to soil temperature and moisture. Parameterization of the spatial model SVAT-CN includes horizontal heterogeneity of over- and understory PAI, understory species distribution, soil texture, bulk density, thickness of organic layer. Simulations are run for intensive observations periods of 2007 and 2008 of the EGER (ExchanGE processes in mountainous Regions) project, a late summer/fall and an early summer period, providing estimates for different understory types (young spruce, blueberry, grass, and moss/litter patches). Validation of the model is being carried out at point scale, by comparison with measured soil moisture and temperature data at 12 locations at the Weidenbrunnen site. In addition model output is compared to soil NO emission data from dynamic chambers. Understory type was found to have a strong influence on the magnitude of soil NO emissions, with emissions from blueberry and young spruce one order of magnitude larger than those from grass or moss/litter patches.

Simulation of soil organic carbon in different soil size fractions using 13Carbon measurement data

NASA Astrophysics Data System (ADS)

Gottschalk, P.; Bellarby, J.; Chenu, C.; Foereid, B.; Wattenbach, M.; Zingore, S.; Smith, J.

2009-04-01

We simulate the soil organic carbon (SOC) dynamics at a chronoseqeunce site in France, using the Rothamsted Carbon model. The site exhibits a transition from C3 plants, dominated by pine forest, to a conventional C4 maize rotation. The different 13C signatures of the forest plants and maize are used to distinguish between the woodland derived carbon (C) and the maize derived C. The model is evaluated against total SOC and C derived from forest and maize, respectively. The SOC dynamics of the five SOC pools of the model, decomposable plant material (DPM), resistant plant material (RPM), biomass, humus and inert C, are also compared to the SOC dynamics measured in different soil size fractions. These fractions are > 50 μm (particulate organic matter), 2-50 μm (silt associated SOC) and <2 μm (clay associated SOC). Other authors had shown that the RPM pool of the model corresponds well to SOC measured in the soil size fraction > 50 μm and the sum of the other pools corresponds well to the SOC measured in the soil size fraction < 50 μm. Default model applications show that the model underestimates the fast drop in forest C stocks in the first 20 years after land-use change and overestimates the C accumulation of maize C. Several hypotheses were tested to evaluate the simulations. Input data and internal model parameter uncertainties had minor effects on the simulations results. Accounting for erosion and implementing a simple tillage routine did not improve the simulation fit to the data. We therefore hypothesize that a generic process that is not yet explicitly accounted for in the ROTHC model could explain the loss in soil C after land use change. Such a process could be the loss of the physical protection of soil organic matter as would be observed following cultivation of a previously uncultivated soil. Under native conditions a fraction of organic matter is protected in stable soil aggregates. These aggregates are physically disrupted by continuous and repeated cultivation of the soil. The underestimation of SOC loss by the model can be mainly attributed to the slow turnover of the humus pool. This pool was shown to represent mainly the SOC associated with the silt and clay soil fraction. Here, the clay associated SOC shows as similar turnover time as the humus pool in the model. We split the humus pool into a clay and a silt associated pool. The clay pool now corresponds to the clay associated SOC with the turnover time of the humus pool. The silt pool now corresponds to the silt associated SOC. From the measurements, the latter has a turnover time similar to the turnover time of the particulate organic matter. We therefore use the turnover time of the RPM pool for the silt pool. These modifications improve the simulations of the forest derived C significantly and improve the simulations of the maize derived C. Future work will further evaluate and refine this approach to eventually capture the SOC dynamics associated with physical protection, including the effect of tillage/no-tillage, in a simple approach.

Atomic composition and electrical characteristics of epitaxial CVD diamond layers doped with boron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Surovegina, E. A., E-mail: suroveginaka@ipmras.ru; Demidov, E. V.; Drozdov, M. N.

2016-12-15

The results of analysis of the atomic composition, doping level, and hole mobility in epitaxial diamond layers when doped with boron are reported. The layers are produced by chemical-vapor deposition. The possibilities of uniform doping with boron to a level in the range 5 × 10{sup 17} to ~10{sup 20} at cm{sup –3} and of δ doping to the surface concentration (0.3–5) × 10{sup 13} at cm{sup –3} are shown. The conditions for precision ion etching of the structures are determined, and barrier and ohmic contacts to the layers are formed.

Propagation Characteristics of Finite Ground Coplanar Waveguide on Si Substrates With Porous Si and Polyimide Interface Layers

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Itotia, Isaac K.; Drayton, Rhonda Franklin

2003-01-01

Measured and modeled propagation characteristics of Finite Ground Coplanar (FGC) waveguide fabricated on a 15 ohm-cm Si substrate with a 23 micron thick, 68% porous Si layer and a 20 micron thick polyimide interface layer are presented for the first time. Attenuation and effective permittivity as function of the FGC geometry and the bias between the center conductor and the ground planes are presented. It is shown that the porous Si reduces the attenuation by 1 dB/cm compared to FGC lines with only polyimide interface layers, and the polyimide on porous silicon demonstrates negligible bias dependence.

A Simplified Representation of the Chemical Nature and Reactions of Soil Humus.

ERIC Educational Resources Information Center

Stevenson, F. J.; Olsen, R. A.

1989-01-01

Presented is a comprehensible structural representation of humic substances. A number of important roles of soil organic matter, including contribution to the cation-exchange capacity, binding of pesticides, and formation of complexes with micronutrient cations, are illustrated. (Author/CW)

Nine year active layer thermal monitoring at Fildes Peninsula, King George Island, Maritime Antarctica

NASA Astrophysics Data System (ADS)

Michel, Roberto; Andrade, André; Simas, Felipe; Silva, Tássio; Loureiro, Diego; Schaefer, Carlos

2017-04-01

Most global circulation models predict enhanced rates of climate change, particularly temperature increase, at higher latitudes witch are currently faced with rapid rates of regional climate change (Convey 2006, Vaughan et al. 2003, Quayle et al. 2002), Antarctic ecosystems are expected to show particular sensitivity and rapid responses (Freckman and Virginia 1997, Quayle et al. 2002, 2003). The active layer and permafrost are important components of the cryosphere due to their role in energy flux regulation and sensitivity to climate change (Kane et al., 2001; Smith and Brown, 2009). Compared with other regions of the globe, our understanding of Antarctic permafrost is poor, especially in relation to its thermal state and evolution, (Bockheim, 1995, Bockheim et al., 2008). The active layer monitoring site was installed in the summer of 2008, and consists of thermistors (accuracy ± 0.2 °C) arranged in a vertical array (Turbic Eutric Cryosol 60 m asl, 10.5 cm, 32.5 cm, 67.5 cm and 83.5 cm). All probes were connected to a Campbell Scientific CR 1000 data logger recording data at hourly intervals from March 1st 2008 until November 30th 2012. We calculated the thawing days (TD), freezing days (FD); thawing degree days (TDD) and freezing degree days (FDD); all according to Guglielmin et al. (2008). The active lawyer thickness was calculated as the 0 °C depth by extrapolating the thermal gradient from the two deepest temperature measurements (Guglielmin, 2006). The temperature at 10.5 cm reaches a maximum daily average (5.6 °C) in late January 2015, reaching a minimum (-9.6 °C) in in early August 2011, at 83.5 cm maximum daily average (0.6 °C) was reached in mid March 2009 and minimum (-5.5 °C) also in early August 2011. The years of 2008, 2009 and 2011 recorded thaw days at the bottom of the profile (62 and 49 in 2009 and 2011), and logged the highest soil moisture contents of the time series (62%, 59% and 63%). Seasonal variability of the active layer shows disparities between different years, especially in bottom most layer, where high summer temperatures trigger a increase in soil moisture content that can endure for several seasons. The winter of 2014 also deserves special attention, being the mildest winter recorded during the studied period; in July minimum monthly temperatures were -3.2 °C and -1.9 °C at 10.5 cm and 83.5 cm, it experienced 17 FD summing -0.61 FDD, average for the whole period was -7.5 °C, -3.9 °C, 27 FD and -55 FDD (2008 also had a mild winter but still hold 21 FD and -0,88 FDD at 83.5 cm in July). The summer of 2009 was the warmest facing 31 thawing days and summing 105 thawing degree days at 10.5 cm in January (28.7 thawing days and 66.3 thawing degree days average). The profile showed a increase in soil water content annual during warm summers, persisting for the following seasons, average is 44 % in 2008, 32 % in 2012 closing the time series with a annual average of 27 % in 2016, all values at 83.5 cm. Active layer thickness varied between 86 cm (max of 2015, March) and 117 cm (max of 2009, March). The active layer thermal regime over a 9 year period at Fildes Peninsula shows great variation between years, 2008, 2009 and 2011 presenting warm summers and 2014 being abnormally warm during Winter. Temperature fluctuations can affect the active layer in depth and the effects of warmer temperatures in the bottom of the profile can increase soil water content for several seasons.

[Spatial variation of soil phosphorus in flooded area of the Yellow River based on GIS and geo-statistical methods: A case study in Zhoukou City, Henan, China.

PubMed

Jia, Zhen Yu; Zhang, Jun Hua; Ding, Sheng Yan; Feng, Shu; Xiong, Xiao Bo; Liang, Guo Fu

2016-04-22

Soil phosphorus is an important indicator to measure the soil fertility, because the content of soil phosphorus has an important effect on physical and chemical properties of soil, plant growth, and microbial activity in soil. In this study, the soil samples collecting and indoor analysis were conducted in Zhoukou City located in the flooded area of the Yellow River. By using GIS combined with geo-statistics, we tried to analyze the spatial variability and content distribution of soil total phosphorus (TP) and soil available phosphorus (AP) in the study area. Results showed that TP and AP of both soil layers (0-20 cm and 20-40 cm) were rich, and the contents of TP and AP in surface layer (0-20 cm) were higher than in the second layer (20-40 cm). TP and AP of both soil layers exhibited variation at medium level, and AP had varied much higher than TP. TP of both layers showed medium degree of anisotropy which could be well modeled by the Gaussian model. TP in the surface layer showed strong spatial correlation, but that of the second layer had medium spatial correlation. AP of both layers had a weaker scope in anisotropy which could be simulated by linear model, and both soil layers showed weaker spatial correlations. TP of both soil layers showed a slowly rising change from southwest to northeast of the study area, while it gradually declined from northwest to southeast. AP in soil surface layer exhibited an increase tendency firstly and then decrease from southwest to the northeast, while it decreased firstly and then increased from southeast to the northwest. AP in the second soil layer had an opposite change in the southwest to the northeast, while it showed continuously increasing tendency from northwest to the southeast. The contents of TP and AP in the surface layer presented high grades and the second layer of TP belonged to medium grade, but the second layer of AP was in a lower grade. The artificial factors such as land use type, cropping system, irrigation and fertilization were the main factors influencing the distribution and spatial variation of soil phosphorus in this area.

Experimental study on the heat transfer characteristics of waste printed circuit boards pyrolysis.

PubMed

Ma, Hongting; Du, Na; Lin, Xueyin; Li, Chen; Lai, Junwen; Li, Zihao

2018-08-15

In order to study the appropriate and advanced technology for recycling waste printed circuit boards (PCBs), a fixed bed pyrolysis device with stirring function has been designed and developed. The effect of rotating speed on the temperature distribution and mass change in the pyrolysis process of FR-4 PCB has been analyzed. The heat transfer and pyrolysis characteristics of different granular layers with and without stirring have been investigated. The results indicate that the stirring can change the main way of heat transfer from conduction to convection in the PCB layers. As the increase of rotating speed, the temperature rising rate of material at the bottom of the pyrolysis furnace gradually decreases, while the heating rate is increasing at the upper layer, and the temperature difference between the upper and bottom layers is gradually reduced. When the rotating speed varies from 0r/min to 18r/min, the weight loss of the material increases from 3.97% to 6.76%, and the overall pyrolysis degree is improved. During the pyrolysis process, the material layer can be divided into three zones along the vertical direction, namely complete pyrolysis zone, partial pyrolysis zone and non-pyrolysis zone. As the rotating speed is 0r/min, the thickness of each zones is 6cm, 6cm and 3cm, respectively. However, when the rotating speed is increased to 18r/min, the non-pyrolysis zone disappears, and the thickness of complete pyrolysis zone and partial pyrolysis zone increase to 9cm and 6cm, respectively. Copyright © 2018 Elsevier B.V. All rights reserved.

Fate and transport of carbamazepine in soil aquifer treatment (SAT) infiltration basin soils.

PubMed

Arye, Gilboa; Dror, Ishai; Berkowitz, Brian

2011-01-01

The transport and fate of the pharmaceutical carbamazepine (CBZ) were investigated in the Dan Region Reclamation Project (SHAFDAN), Tel-Aviv, Israel. Soil samples were taken from seven subsections of soil profiles (150 cm) in infiltration basins of a soil aquifer treatment (SAT) system. The transport characteristics were studied from the release dynamics of soil-resident CBZ and, subsequently, from applying a pulse input of wastewater containing CBZ. In addition, a monitoring study was performed to evaluate the fate of CBZ after the SAT. Results of this study indicate adsorption, and consequently retardation, in CBZ transport through the top soil layer (0-5 cm) and to a lesser extent in the second layer (5-25 cm), but not in deeper soil layers (25-150 cm). The soluble and adsorbed fractions of CBZ obtained from the two upper soil layers comprised 45% of the total CBZ content in the entire soil profile. This behavior correlated to the higher organic matter content observed in the upper soil layers (0-25 cm). It is therefore deduced that when accounting for the full flow path of CBZ through the vadose zone to the groundwater region, the overall transport of CBZ in the SAT system is essentially conservative. The monitoring study revealed that the average concentration of CBZ decreased from 1094 ± 166 ng L⁻¹ in the recharged wastewater to 560 ± 175 ng L⁻¹ after the SAT. This reduction is explained by dilution of the recharged wastewater with resident groundwater, which may occur as it flows to active reclamation wells. Copyright © 2010 Elsevier Ltd. All rights reserved.

Phylogenetic analysis of Archaea in the deep-sea sediments of west Pacific Warm Pool.

PubMed

Wang, Peng; Xiao, Xiang; Wang, Fengping

2005-06-01

Archaea are known to play important roles in carbon cycling in marine sediments. The main compositions of archaeal community in five deep-sea sediment samples collected from west Pacific Warm Pool area (WP-0, WP-1, WP-2, WP-3, WP-4), and in five sediment layers (1 cm-, 3 cm-, 6 cm-, 10 cm-, 12 cm- layer) of the 12 cm sediment core of WP-0 were checked and compared by denaturing gradient gel electrophoresis and 16 S rRNA gene sequencing. It was revealed that all the deep-sea sediment samples checked contained members of non-thermophilic marine group I crenarchaeota as the predominant archaeal group. To further detect groups of archaea possibly relating with C1 metabolism, PCR amplification was carried out using primers targeting methane-oxidizing archaea. Although no methane-oxidizing archaea was detected, a group of novel archaea (named as WPA) was instead identified from all these five WP samples by clone analysis. They could be placed in the euryarchaeota kingdom, separated into two distinct groups, the main group was peripherally related with methanogens, the other group related with Thermoplasma. The vertical distributions of WPA, archaea and bacteria along the WP-0 sediment column were determined by quantitative-PCR. It was found that bacteria dominated at all depths, the numbers of bacteria were 10-10(4) times more than those of archaea. The proportion of archaea versus bacteria had a depth related increasing tendency, it was lowest at the first layer (0.01%), reached highest at the 12 cm- layer (10%). WPA only constituted a small proportion of the archaeal community (0.05% to 5%) of west Pacific Warm Pool sediment.

Synergistic approach to high-performance oxide thin film transistors using a bilayer channel architecture.

PubMed

Yu, Xinge; Zhou, Nanjia; Smith, Jeremy; Lin, Hui; Stallings, Katie; Yu, Junsheng; Marks, Tobin J; Facchetti, Antonio

2013-08-28

We report here a bilayer metal oxide thin film transistor concept (bMO TFT) where the channel has the structure: dielectric/semiconducting indium oxide (In2O3) layer/semiconducting indium gallium oxide (IGO) layer. Both semiconducting layers are grown from solution via a low-temperature combustion process. The TFT mobilities of bottom-gate/top-contact bMO TFTs processed at T = 250 °C are ~5tmex larger (~2.6 cm(2)/(V s)) than those of single-layer IGO TFTs (~0.5 cm(2)/(V s)), reaching values comparable to single-layer combustion-processed In2O3 TFTs (~3.2 cm(2)/(V s)). More importantly, and unlike single-layer In2O3 TFTs, the threshold voltage of the bMO TFTs is ~0.0 V, and the current on/off ratio is significantly enhanced to ~1 × 10(8) (vs ~1 × 10(4) for In2O3). The microstructure and morphology of the In2O3/IGO bilayers are analyzed by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, revealing the polycrystalline nature of the In2O3 layer and the amorphous nature of the IGO layer. This work demonstrates that solution-processed metal oxides can be implemented in bilayer TFT architectures with significantly enhanced performance.

Temperature Dependence of Raman-Active In-Plane E2g Phonons in Layered Graphene and h-BN Flakes

NASA Astrophysics Data System (ADS)

Li, Xiaoli; Liu, Jian; Ding, Kai; Zhao, Xiaohui; Li, Shuai; Zhou, Wenguang; Liang, Baolai

2018-01-01

Thermal properties of sp2 systems such as graphene and hexagonal boron nitride (h-BN) have attracted significant attention because of both systems being excellent thermal conductors. This research reports micro-Raman measurements on the in-plane E2g optical phonon peaks ( 1580 cm-1 in graphene layers and 1362 cm-1 in h-BN layers) as a function of temperature from - 194 to 200 °C. The h-BN flakes show higher sensitivity to temperature-dependent frequency shifts and broadenings than graphene flakes. Moreover, the thermal effect in the c direction on phonon frequency in h-BN layers is more sensitive than that in graphene layers but on phonon broadening in h-BN layers is similar as that in graphene layers. These results are very useful to understand the thermal properties and related physical mechanisms in h-BN and graphene flakes for applications of thermal devices.

Effects of TiO2 electron blocking layer on photovoltaic performance of photo-electrochemical cell

NASA Astrophysics Data System (ADS)

Bin, Jae-Wook; Kim, Doo-Hwan; Sung, Youl-Moon; Park, Min-Woo

2014-06-01

Dye-sensitized solar cells (DSCs) have used transparent conductive Fluorine-doped SnO2 (FTO) glass/porous TiO2 layer attached using dye molecules/electrolytes (I-/I3-)/Platinium-coated FTO glass configuration. In this work, prior to the coating of nanoporous TiO2 layer on FTO glass, a dense layer of TiO2 film with a thickness of less than ∼100 nm was deposited directly onto the FTO as an electron blocking layer by radio frequency (RF) magnetron sputtering. Under 100 mW/cm2 illumination at AM 1.5, the energy conversion efficiency (η) of the prepared DSC with electron blocking layer of 80 nm thickness was 6.9% (Voc = 0.67 V, Jsc = 12.18 mA/cm2, ff = 0.63), which is increased by 1.3% compared to the typical cell without electron blocking layer.

Runoff processes in catchments with a small scale topography

NASA Astrophysics Data System (ADS)

Feyen, H.; Leuenberger, J.; Papritz, A.; Gysi, M.; Flühler, H.; Schleppi, P.

1996-05-01

How do runoff processes influence nitrogen export from forested catchments? To support nitrogen balance studies for three experimental catchments (1500m 2) in the Northern Swiss prealps water flow processes in the two dominating soil types are monitored. Here we present the results for an experimental wetland catchment (1500m 2) and for a delineated sloped soil plot (10m 2), both with a muck humus topsoil. Runoff measurements on both the catchment and the soil plot showed fast reactions of surface and subsurface runoff to rainfall inputs, indicating the dominance of fast-flow paths such as cracks and fissures. Three quarters of the runoff from the soil plot can be attributed to water flow in the gleyic, clayey subsoil, 20% to flow in the humic A horizon and only 5% to surface runoff. The water balance for the wetland catchment was closed. The water balance of the soil plot did not close. Due to vertical upward flow from the saturated subsoil into the upper layers, the surface runoff plus subsurface runoff exceeded the input (precipitation) to the plot.

Active layer thermal monitoring at Fildes Peninsula, King George Island, Maritime Antarctica

NASA Astrophysics Data System (ADS)

Michel, Roberto; Schaefer, Carlos; Simas, Felipe; Pregesbauer, Michael; Bockheim, James

2013-04-01

International attention on the climate change phenomena has grown in the last decade, intense modelling of climate scenarios were carried out by scientific investigations searching the sources and trends of these changes. The cryosphere and its energy flux became the focus of many investigations, being recognised as a key element for the understanding of future trends. The active layer and permafrost are key components of the terrestrial cryosphere due to their role in energy flux regulation and high sensitivity to climate change (Kane et al., 2001; Smith and Brown, 2009). Compared with other regions of the globe, our understanding of Antarctic permafrost is poor, especially in relation to its thermal state and evolution, its physical properties, links to pedogenesis, hydrology, geomorphic dynamics and response to global change (Bockheim, 1995, Bockheim et al., 2008). The active layer monitoring site was installed in the summer of 2008, and consist of thermistors (accuracy ± 0.2 °C) arranged in a vertical array (Turbic Eutric Cryosol 600 m asl, 10.5 cm, 32.5 cm, 67.5 cm and 83.5 cm). King George Island experiences a cold moist maritime climate characterized by mean annual air temperatures of -2°C and mean summer air temperatures above 0°C for up to four months (Rakusa-Suszczewski et al., 1993, Wen et al., 1994). Ferron et al., (2004) found great variability when analysing data from 1947 to1995 and identified cycles of 5.3 years of colder conditions followed by 9.6 years of warmer conditions. All probes were connected to a Campbell Scientific CR 1000 data logger recording data at hourly intervals from March 1st 2008 until November 30th 2012. Meteorological data for Fildes was obtained from the near by stations. We calculated the thawing days, freezing days; thawing degree days and freezing degree days; all according to Guglielmin et al. (2008). The active lawyer thickness was calculated as the 0 °C depth by extrapolating the thermal gradient from the two deepest temperature measurements (Guglielmin, 2006). Interannual variability of the active layer shows parallel behaviour despite contrasts between different years, the temperature at 10.5 cm reaches a maximum daily average (4.06 °C ± 0.46) in early January, reaching a minimum (-8.03 °C ± 1,36) between late July and early August. At 83.5 cm maximum temperature (0.30 °C ± 0.24) occurs in late March and the minimum reading (-4.06 °C ± 0.98) was recorded around mid August. Disparities can be noticed when comparing the different years; 2008 had a mild winter (21 freezing days and -0,88 freezing degree days at 83.5 cm in July) contrasted by a severe winter in 2011 (31 freezing days and -80,00 freezing degree days at 83.5 cm in July), the summer of 2009 was considerably warmer (31 thawing days and 64,77 thawing degree days at 10.5 cm in January ) compared to the summer of 2010 (17 thawing days and 21,15 thawing degree days at 10.5 cm in January). Active layer thickness varied between 67 cm (max of 2012, March) and 101 cm (max of 2009, March). The active layer thermal regime in the studied period for both soils was typical of periglacial environments, with extreme variation in surface during summer resulting in frequent freeze and thaw cycles. Despite the variability when comparing temperature readings and active layer thickness over the studied period no trend can be identified.

Soil morphology of a debris flow chronosequence in a coniferous forest, southern California, USA

USGS Publications Warehouse

Turk, J.K.; Goforth, B.R.; Graham, R.C.; Kendrick, K.J.

2008-01-01

Soils on a series of debris flow deposits, ranging from < 1 to 244??years old, were described and sampled in order to investigate the early stages of soil development. The parent material at the site is debris flow regolith, composed mainly of gneiss, the soil moisture regime is xeric, and the vegetation is mixed coniferous forest. Ages of the deposits were assessed using dendrochronology. Morphologic trends in the organic horizons included a thickening of the humus form over time, along with the development of Fm and Hr horizons. The humus forms underwent a progression from Mormodors (20??years old), to Hemimors (26-101??years old), and finally Lignomors (163??years old) and Resimors (184-244??years old). Changes in physical properties of the uppermost mineral horizons as a function of increasing age included a decrease in the volume of coarse fragments, a linear decrease in bulk density, and a darkening and reddening of the soil color. No significant soil development took place in the subsoil during the time span of this chronosequence. The soils described were classified as Typic Xerofluvents and Typic Xerorthents (Regosols and Leptosols). Buried A horizons were observed in many of the soils. Where the A horizons could be linked to dendrochronology to assess the age of the buried surface, we found that the properties of the buried A horizons do not serve as a good indicator of the age of the surface. This study suggests rapid development of the humus form profile (organic horizons and A horizon) following debris flow deposition and rapid degradation of these horizons when the debris flow surface is buried. ?? 2008 Elsevier B.V.

Phenolic acids as bioindicators of fly ash deposit revegetation.

PubMed

Djurdjević, L; Mitrović, M; Pavlović, P; Gajić, G; Kostić, O

2006-05-01

The floristic composition, the abundance, and the cover of pioneer plant species of spontaneously formed plant communities and the content of total phenolics and phenolic acids, as humus constituents, of an ash deposit after 7 years of recultivation were studied. The restoration of both the soil and the vegetation on the ash deposits of the "Nikola Tesla-A" thermoelectric power plant in Obrenovac (Serbia) is an extremely slow process. Unfavorable physical and chemical characteristics, the toxicity of fly ash, and extreme microclimatic conditions prevented the development of compact plant cover. The abundance and cover of plants increased from the central part of the deposit towards its edges (ranging from 1-80%). Festuca rubra L., Crepis setosa Hall., Erigeron canadensis L., Cirsium arvense (L.) Scop., Calamagrostis epigeios (L.) Roth., and Tamarix gallica L. were the most abundant species, thus giving the highest cover. Humus generated during the decomposition process of plant remains represents a completely new product absent in the ash as the starting material. The amount of total phenolics and phenolic acids (38.07-185.16 microg/g of total phenolics and 4.12-27.28 microg/g of phenolic acids) in fly ash increased from the center of the deposit towards its edges in correlation with the increase in plant abundance and cover. Ash samples contained high amounts of ferulic, vanillic, and p-coumaric acid, while the content of both p-hydroxybenzoic and syringic acid was relatively low. The presence of phenolic acids indicates the ongoing process of humus formation in the ash, in which the most abundant pioneer plants of spontaneously formed plant communities play the main role. Phenolic compounds can serve as reliable bioindicators in an assessment of the success of the recultivation process of thermoelectric power plants' ash deposits.

Dual active layer a-IGZO TFT via homogeneous conductive layer formation by photochemical H-doping

PubMed Central

2014-01-01

In this study, InGaZnO (IGZO) thin film transistors (TFTs) with a dual active layer (DAL) structure are fabricated by inserting a homogeneous embedded conductive layer (HECL) in an amorphous IGZO (a-IGZO) channel with the aim of enhancing the electrical characteristics of conventional bottom-gate-structure TFTs. A highly conductive HECL (carrier concentration at 1.6 × 1013 cm-2, resistivity at 4.6 × 10-3 Ω∙cm, and Hall mobility at 14.6 cm2/Vs at room temperature) is fabricated using photochemical H-doping by irradiating UV light on an a-IGZO film. The electrical properties of the fabricated DAL TFTs are evaluated by varying the HECL length. The results reveal that carrier mobility increased proportionally with the HECL length. Further, a DAL TFT with a 60-μm-long HECL embedded in an 80-μm-long channel exhibits comprehensive and outstanding improvements in its electrical properties: a saturation mobility of 60.2 cm2/Vs, threshold voltage of 2.7 V, and subthreshold slope of 0.25 V/decade against the initial values of 19.9 cm2/Vs, 4.7 V, and 0.45 V/decade, respectively, for a TFT without HECL. This result confirms that the photochemically H-doped HECL significantly improves the electrical properties of DAL IGZO TFTs. PMID:25435832

Dual active layer a-IGZO TFT via homogeneous conductive layer formation by photochemical H-doping.

PubMed

Jeong, Seung-Ki; Kim, Myeong-Ho; Lee, Sang-Yeon; Seo, Hyungtak; Choi, Duck-Kyun

2014-01-01

In this study, InGaZnO (IGZO) thin film transistors (TFTs) with a dual active layer (DAL) structure are fabricated by inserting a homogeneous embedded conductive layer (HECL) in an amorphous IGZO (a-IGZO) channel with the aim of enhancing the electrical characteristics of conventional bottom-gate-structure TFTs. A highly conductive HECL (carrier concentration at 1.6 × 10(13) cm(-2), resistivity at 4.6 × 10(-3) Ω∙cm, and Hall mobility at 14.6 cm(2)/Vs at room temperature) is fabricated using photochemical H-doping by irradiating UV light on an a-IGZO film. The electrical properties of the fabricated DAL TFTs are evaluated by varying the HECL length. The results reveal that carrier mobility increased proportionally with the HECL length. Further, a DAL TFT with a 60-μm-long HECL embedded in an 80-μm-long channel exhibits comprehensive and outstanding improvements in its electrical properties: a saturation mobility of 60.2 cm(2)/Vs, threshold voltage of 2.7 V, and subthreshold slope of 0.25 V/decade against the initial values of 19.9 cm(2)/Vs, 4.7 V, and 0.45 V/decade, respectively, for a TFT without HECL. This result confirms that the photochemically H-doped HECL significantly improves the electrical properties of DAL IGZO TFTs.

Active Layer moisture and temperature monitoring at Half Moon Island, Maritime Antarctica.

NASA Astrophysics Data System (ADS)

Michel, Roberto; Francelino, Márcio; Schaefer, Carlos; Schmitz, Daniela; Dittmar, Camila; Silva, Tássio; Loureiro, Diego

2017-04-01

Half Moon Island is a minor Antarctic island, lying in the Half Moon Bay, Livingston Island in the South Shetland Islands of the Antarctic Peninsula region. Having the Mc Farlane Strait at its western shore the island was formed by the junction of three smaller islands during the Holocene, altitude at its northern portion can reach 101 m a.s.l. Its surface area is 171 hectares (420 acres). The Argentine Cámara Base is located on the island, the naval base is operational occasionally during the summer, when it's water suply comes from a near by lake. Permafrost spreads over wider areas on higher Holocene beaches being sporadic on the lowest Present-day platforms (López-Martínez et al., 2012), processes related to the presence of permafrost were observed. The mean annual air temperature is near -2°C, and average summer temperatures are higher than 0°C. These conditions allow snow cover melting and freeze-thaw cycles during summer although the annual number of air freeze-thaw cycles reported for the near by Byers Peninsula is low, 14 in summer (Blümel and Eitel, 1989; Qingsong, 1989). The objective of this study was to evaluate soil temperature and moisture content based on in situ measurements from a Cryosol developed on a Holocene beach at Half Moon Island, Maritime Antarctica. The monitoring systems consist of soil temperature probes (Campbell L107E thermocouple, accuracy of ± 0.2°C) and soil moisture probes (CS656 water content reflectometer, accuracy of ± 2.5%), placed in the active layer (Turbic Eutric Cryosol 44 m a.s.l., 5 cm, 10 cm, 30 cm, 50 cm and 100 cm, S 62°35´23.8", W 059°55´18.3"). All probes were connected to a Campbell Scientific CR 1000 data logger, recording data at every 1 hour interval. We calculated the thawing days (TD), freezing days (FD) and freezing degree days (FDD); all according to Guglielmin et al. (2008). This system recorded data of soil temperature and moisture from March 2015 to December 2016. Despite the absence of glaciers in the Island the thermal regime of the active layer showed a dominance of freezing conditions (average -1.74 °C at 5 cm and -1.46 °C at 100 cm), thaw days are concentrated February and March (44 from January until November 2016 at 5 cm being missing at 50 cm and 100 cm). At 100 cm the majority of the 642 days are classified as freeze days (192 days). Soil moisture content was very similar for 2015 and 2016, averaging 0.11, m3 m-3 (0.41 max, 0.04 min) and 0.13 m3 m-3 (0.39 max, 0.07 min) at 10 cm and 100, for the whole study period. Considering the cold season 2015 was colder, FDD summed -806 degree days at 5 cm and -674 at 100 cm (-392 and -315 degree days in 2016). Nevertheless active layer thickness reached its maximum of 140 cm in late march 2015 (118 in 2016). During the 2015 summer season the lake that supply's water to Argentine Cámara Base drained, apparently the deepening of the active layer disrupted the drainage impediment provided by the permafrost table. The active layer thermal regime over 642 day period at Half Moon Island shows a preponderance of freezing conditions; although summer data is not available for 2015, the active layer thickness reached its maximum during late march retracting in 2016.

Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy

PubMed Central

Brooks, Emily K.; Tobias, Menachem E.; Yang, Shuying; Bone, Lawrence B.; Ehrensberger, Mark T.

2015-01-01

This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin) and outer layer resistance (Rout) were lower for samples without cells cultured on the surface at 3 days (Rin = 2.64 e4 Ω/cm2, Rout = 140 Ω/cm2) compared to 21 days (Rin = 3.60 e4 Ω/cm2, Rout = 287 Ω/cm2) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin = 1.88 e5 Ω/cm2, Rout = 1060 Ω/cm2) which was observed to increase over time (21 day, Rin = 2.99 e4 Ω/cm2, Rout = 287 Ω/cm2). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. PMID:25715925

[Characteristics of soil moisture in artificial impermeable layers].

PubMed

Suo, Gai-Di; Xie, Yong-Sheng; Tian, Fei; Chuai, Jun-Feng; Jing, Min-Xiao

2014-09-01

For the problem of low water and fertilizer use efficiency caused by nitrate nitrogen lea- ching into deep soil layer and soil desiccation in dryland apple orchard, characteristics of soil moisture were investigated by means of hand tamping in order to find a new approach in improving the water and fertilizer use efficiency in the apple orchard. Two artificial impermeable layers of red clay and dark loessial soil were built in soil, with a thickness of 3 or 5 cm. Results showed that artificial impermeable layers with the two different thicknesses were effective in reducing or blocking water infiltration into soil and had higher seepage controlling efficiency. Seepage controlling efficiency for the red clay impermeable layer was better than that for the dark loessial soil impermeable layer. Among all the treatments, the red clay impermeable layer of 5 cm thickness had the highest bulk density, the lowest initial infiltration rate (0.033 mm · min(-1)) and stable infiltration rate (0.018 mm · min(-1)) among all treatments. After dry-wet alternation in summer and freezing-thawing cycle in winter, its physiochemical properties changed little. Increase in years did not affect stable infiltration rate of soil water. The red clay impermeable layer of 5 cm thickness could effectively increase soil moisture content in upper soil layer which was conducive to raise the water and nutrient use efficiency. The approach could be applied to the apple production of dryland orchard.

Vertical migration of plutonium-239 + -240, americium-241 and caesium-137 fallout in a forest soil under spruce.

PubMed

Bunzl, K; Kracke, W; Schimmack, W

1992-03-01

The vertical activity distributions of fallout 238Pu, 239+240Pu, 241Am, 134Cs and 137Cs in a forest soil (Hapludult) were determined at several locations in a spruce stand separately according to their origin (global fallout or Chernobyl fallout). To determine the rate of migration of these radionuclides in each soil horizon, the observed depth profiles of the radionuclides were evaluated with a compartment model. In the top organic horizons (LOf1 and Of2), the migration rates for all radionuclides from both sources were above 0.5 cm per year. In the Oh horizon the migration rates observed for global fallout Pu, Am and Cs were similar (0.2-0.4 cm per year). Compared with Pu, however, the mobility of Am is slightly, but statistically significantly, enhanced. The highest rate in this layer was found for Chernobyl-derived radiocaesium (2 cm per year). In the layers of the mineral horizon (depth 0-2, 2-5 and 5-10 cm) the observed migration rates were very similar for global fallout Pu (0.08-0.7 cm per year) and Am (0.1-2 cm per year). In comparison, the migration rate of global fallout radiocaesium was about half in each layer. The highest rate was observed again for Chernobyl-derived radiocaesium (0.5-3 cm per year).

A thin layer electrochemical cell for disinfection of water contaminated with Staphylococcus aureus

PubMed Central

Gusmão, Isabel C. P.; Moraes, Peterson B.; Bidoia, Ederio D.

2009-01-01

A thin layer electrochemical cell was tested and developed for disinfection treatment of water artificially contaminated with Staphylococcus aureus. Electrolysis was performed with a low-voltage DC power source applying current densities of 75 mA cm-2 (3 A) or 25 mA cm-2 (1 A). A dimensionally stable anode (DSA) of titanium coated with an oxide layer of 70%TiO2 plus 30%RuO2 (w/w) and a 3 mm from a stainless-steel 304 cathode was used in the thin layer cell. The experiments were carried out using a bacteria suspension containing 0.08 M sodium sulphate with chloride-free to determine the bacterial inactivation efficacy of the thin layer cell without the generation of chlorine. The chlorine can promote the formation of trihalomethanes (THM) that are carcinogenic. S. aureus inactivation increased with electrolysis time and lower flow rate. The flow rates used were 200 or 500 L h-1. At 500 L h-1 and 75 mA cm-2 the inactivation after 60 min was about three logs of decreasing for colony forming units by mL. However, 100% inactivation for S. aureus was observed at 5.6 V and 75 mA cm-2 after 30 min. Thus, significant disinfection levels can be achieved without adding oxidant substances or generation of chlorine in the water. PMID:24031410

Distinct bacterial assemblages reside at different depths in Arctic multiyear sea ice.

PubMed

Hatam, Ido; Charchuk, Rhianna; Lange, Benjamin; Beckers, Justin; Haas, Christian; Lanoil, Brian

2014-10-01

Bacterial communities in Arctic sea ice play an important role in the regulation of nutrient and energy dynamics in the Arctic Ocean. Sea ice has vertical gradients in temperature, brine salinity and volume, and light and UV levels. Multiyear ice (MYI) has at least two distinct ice layers: old fresh ice with limited permeability, and new saline ice, and may also include a surface melt pond layer. Here, we determine whether bacterial communities (1) differ with ice depth due to strong physical and chemical gradients, (2) are relatively homogenous within a layer, but differ between layers, or (3) do not vary with ice depth. Cores of MYI off northern Ellesmere Island, NU, Canada, were subsectioned in 30-cm intervals, and the bacterial assemblage structure was characterized using 16S rRNA gene pyrotag sequencing. Assemblages clustered into three distinct groups: top (0-30 cm); middle (30-150 cm); and bottom (150-236 cm). These layers correspond to the occurrence of refrozen melt pond ice, at least 2-year-old ice, and newly grown first-year ice at the bottom of the ice sheet, respectively. Thus, MYI houses multiple distinct bacterial assemblages, and in situ conditions appear to play a less important role in structuring microbial assemblages than the age or conditions of the ice at the time of formation. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Variations in bacterial and fungal communities through soil depth profiles in a Betula albosinensis forest.

PubMed

Du, Can; Geng, Zengchao; Wang, Qiang; Zhang, Tongtong; He, Wenxiang; Hou, Lin; Wang, Yueling

2017-09-01

Microbial communities in subsurface soil are specialized for their environment, which is distinct from that of the surface communities. However, little is known about the microbial communities (bacteria and fungi) that exist in the deeper soil horizons. Vertical changes in microbial alpha-diversity (Chao1 and Shannon indices) and community composition were investigated at four soil depths (0-10, 10-20, 20-40, and 40-60 cm) in a natural secondary forest of Betula albosinensis by high-throughput sequencing of the 16S and internal transcribed spacer rDNA regions. The numbers of operational taxonomic units (OTUs), and the Chao1 and Shannon indices decreased in the deeper soil layers. Each soil layer contained both mutual and specific OTUs. In the 40-60 cm soil layer, 175 and 235 specific bacterial and fungal OTUs were identified, respectively. Acidobacteria was the most dominant bacterial group in all four soil layers, but reached its maximum at 40-60 cm (62.88%). In particular, the 40-60 cm soil layer typically showed the highest abundance of the fungal genus Inocybe (47.46%). The Chao1 and Shannon indices were significantly correlated with the soil organic carbon content. Redundancy analysis indicated that the bacterial communities were closely correlated with soil organic carbon content (P = 0.001). Collectively, these results indicate that soil nutrients alter the microbial diversity and relative abundance and affect the microbial composition.

Material growth and characterization for solid state devices

NASA Technical Reports Server (NTRS)

Stefanakos, E. K.; Collis, W. J.; Abul-Fadl, A.; Iyer, S.

1984-01-01

During the reporting period, InGaAs was grown on Fe-doped (semi-insulating) (100) InP substrates by current controlled liquid phase epitaxy (CCLPE) at 640 C and current densities of 2.5A sq/cm to 5 A/sq cm for periods from 5 to 30 minutes. Special efforts were made to reduce the background carrier concentration in the grown layers as much as possible. The best layers exhibited carrier concentrations in the mid-10 to the 15th power/cu cm range and up to 10,900 sq cm/V-sec room temperature mobility. InGaAsP quaternary layers of energy gap corresponding to wavelengths of approximately 1.5 microns and 1.3 microns were grown on (100) InP substrates by CCLPE. In the device fabrication area, work was directed toward processing MISFET's using InGaAs. SiO2, Si3N4 and Al2O3 were deposited by ion beam sputtering, electron beam evaporation and chemical vapor reaction on Si, GaAs, and InGaAs substrates. SiO2 and Si3N4 sputtered layers were found to possess a high density of pinhole defects that precluded capacitance-voltage analysis. Chemical vapor deposited Al2O3 layers on Si, GaAs and InGaAs substrates also exhibited a large number of pinhole defects. This prevented achieving good MIS devices over most of the substrate surface area.

Soil Respiration Controls Ionic Nutrient Concentration In Percolating Water In Rice Fields

NASA Astrophysics Data System (ADS)

Kimura, M.

2004-12-01

Soil water in the plow layer in rice fields contains various kinds of cations and anions, and they are lost from the plow layer by water percolation. Some portions of CO2 produced by respirations of rice roots and soil microorganisms are also leached by water percolation to the subsoil layer as HCO3-. As the electrical neutrality of inorganic substances in percolating water is maintained when they are assumed to be in the form of simple cations and anions, soil respiration accelerates the leaching of ionic nutrients from the plow layer by water percolation. The proportion of inorganic carbon (Σ CO2) originated from photosynthates in the total Σ CO2 in soil solution in the plow layer was from 28 to 36 % in the rice straw amended soil and from 16 to 31 % in the soil without rice straw amendment in a soil pot experiment with rice plant after the maximum tillering stage. Most of Σ CO2 in percolating water from the plow layer accumulates in the subsoil layer. Periodical measurement of Σ CO2 in percolating water at 13 and 40 cm soil depths indicated that 10 % of total soil organic C in the plow layer was leached down from the plow layer (13 cm), and that about 90 % of it was retained in the subsoil layer to the depth of 40 cm. Water soluble organic materials are also leached from the plow layer by water percolation, and the leaching is accelerated by soil reduction. Soil reduction decreased the content of organic materials that were bound with ferric iron in soil (extractable by 0.1M Na4P2O7 + NaBH4) and increased the content of organic materials that were extractable by the neutral chelating solution (0.1M Na4P2O7). In addition, water percolation transformed the latter organic materials to those that were extractable by water and a neutral salt. Considerable portions of organic materials in percolating water are adsorbed in the subsoil layer, and then partially decomposed and polymerized to specific soil organic materials in the subsoil. Organic materials that were leached from the plow layer by percolating water amounted to 170 kgC ha-1 in a Japanese rice field, among which 120 kgC of organic materials were adsorbed in the subsoil layer between 13 and 40 cm depth.

Deposition and characterization of spray pyrolysed p-type Cu2SnS3 thin film for potential absorber layer of solar cell

NASA Astrophysics Data System (ADS)

Thiruvenkadam, S.; Sakthi, P.; Prabhakaran, S.; Chakravarty, Sujay; Ganesan, V.; Rajesh, A. Leo

2018-06-01

Thin film of ternary Cu2SnS3 (CTS), a potential absorber layer for solar cells was successfully deposited by chemical spray pyrolysis technique. The GIXRD pattern revealed that the film having tetragonal Cu2SnS3 phase with the preferential orientation along (112), (200), (220) and (312) plane and it is further confirmed using Raman spectroscopy by the existence of Raman peak at 320 cm-1. Atomic Force Microscopy (AFM) was used to estimate the surface roughness of 28.8 nm. The absorption coefficient was found to be greater than the order of 105 cm-1 and bandgap of 1.70 eV. Hall effect measurement indicates the p type nature of the film with a hole concentration of 1.03 × 1016cm-3 and a hall mobility of 404 cm2/V. The properties of CTS thin film confirmed suitable to be a potential absorber layer material for photovoltaic applications.

Few layered MoO3 nano sheets-SWCNT composite thin film as supercapacitor electrode

NASA Astrophysics Data System (ADS)

Dutta, Shibsankar; Akther, Jasim; De, Sukanta

2017-05-01

The increasing demands for clean and renewable energy, the advantages of high power density, long lasting and high efficiency have made Supercapacitor as one of the major emerging energy storage device.The 2D layered metal oxide nanocomposite with SWCNT is the promising candidate for energy storage and conversion. In this work we exfoliate the crystalline bulk MoO3 by simple liquid phase exfoliation to give multi-layer MoO3 dispersed in a suitable solvent. As the electrical conductivity of MoO3 is very low so, the dispersion was used to make hybrid material with SWCNT dispersion by vacuum filtration. The SWCNT-MoO3 composite showed an areal capacitance value of 1290 µF/cm2 at 10 mV/s in PVA-H2 SO4 solid gel electrolyte. This composite based electrode provides an energy density of 0.092 µWh/cm2 and a power density of 9.54 µW/cm2 at 0.01 mA/cm2

The Formation of Trihalomethanes.

ERIC Educational Resources Information Center

Trussell, R. Rhodes; Umphres, Mark D.

1978-01-01

Reviewed are a number of factors important in the formation of trihalomethanes (THM) including the nature of aquatic humus and the influences of preozonation, bromide, pH, and chlorine. A brief investigation is also conducted into the kinetics of the THM reaction. Several major research needs are represented. (CS)

Effects of alterations of the E. coli lipopolysaccharide layer on membrane permeabilization events induced by Cecropin A.

PubMed

Agrawal, Anurag; Weisshaar, James C

2018-04-22

The outermost layer of Gram negative bacteria is composed of a lipopolysaccharide (LPS) network that forms a dense protective hydrophilic barrier against entry of hydrophobic drugs. At low μM concentrations, a large family of cationic polypeptides known as antimicrobial peptides (AMPs) are able to penetrate the LPS layer and permeabilize the outer membrane (OM) and the cytoplasmic membrane (CM), causing cell death. Cecropin A is a well-studied cationic AMP from moth. Here a battery of time-resolved, single-cell microscopy experiments explores how deletion of sugar layers and/or phosphoryl negative charges from the core oligosaccharide layer (core OS) of K12 E. coli alters the timing of OM and CM permeabilization induced by Cecropin A. Deletion of sugar layers, or phosphoryl charges, or both from the core OS shortens the time to the onset of OM permeabilization to periplasmic GFP and also the lag time between OM permeabilization and CM permeabilization. Meanwhile, the 12-h minimum inhibitory concentration (MIC) changes only twofold with core OS alterations. The results suggest a two-step model in which the core oligosaccharide layers act as a kinetic barrier to penetration of Cecropin A to the lipid A outer leaflet of the OM. Once a threshold concentration has built up at the lipid A leaflet, nucleation occurs and the OM is locally permeabilized to GFP and, by inference, to Cecropin A. Whenever Cecropin A permeabilizes the OM, CM permeabilization always follows, and cell growth subsequently halts and never recovers on the 45 min observation timescale. Copyright © 2018 Elsevier B.V. All rights reserved.

[Effects of long-term fertilization on enzyme activities in black soil of Northeast China].

PubMed

Wang, Shu-Qi; Han, Xiao-Zeng; Qiao, Yun-Fa; Wang, Shou-Yu

2008-03-01

In this paper, black soil samples at the depths of 0-20 cm and 20-40 cm were collected from the Hailun Agricultural Ecology Station of Chinese Academy of Sciences to study the effects of long-term fertilization on their urease, invertase, phosphatase and catalase activities and total C and N contents. The results showed that long-term application of chemical fertilizers and organic manure increased the activities of urease, invertase and phosphatase in 0-20 cm and 20-40 cm soil layers in different degree, and the combined application of them increased the activities of the three enzymes significantly, with an increment of 43.6%-113.2%, 25.9%-79.5% and 14.7%-134.4% in 0-20 cm soil layer and 56.1%-127.2%, 14.5%-113.8% and 16.2%-207.2% in 20-40 cm soil layer, respectively. However, long-term application of chemical fertilizers without organic manure had little effects on catalase activity. The activities of urease, invertase and phosphatase decreased with increasing soil depth. Long-term application of N fertilizer increased urease activity, and P fertilization had obvious positive effect on phosphatase activity. Long-term fertilization also had obvious effects on the soil total C and N contents and C/N ratio.

Succession of the functional microbial communities and the metabolic functions in maize straw composting process.

PubMed

Wei, Huawei; Wang, Liuhong; Hassan, Muhammad; Xie, Bing

2018-05-01

Illumina MiSeq sequencing and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) were applied to study the dynamic changes and effects of microbial community structures as well as the metabolic function of bacterial community in maize straw composting process. Results showed that humic acid contents in loosely combined humus (HA1) and stably combined humus (HA2) increased after composting and Staphylococcus, Cellulosimicrobium and Ochrobactrum possibly participated in the transformation of the process. The bacterial communities differed in different stages of the composting. Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria were reported the dominant phyla throughout the process and the relative abundance of the dominant phyla varied significantly (p < 0.05) over time. Moreover, the total phosphorus (TP) had the greatest influence on the microbial community structure among C/N ratio, available phosphorus (AP) and humic substances. Metabolism, cellular processes and environmental information processing might be the primary functions of microbial community during the composting. Copyright © 2018 Elsevier Ltd. All rights reserved.

Climate Change Impacts for Conterminous USA: An Integrated Assessment Part 2. Models and Validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomson, Allison M.; Rosenberg, Norman J.; Izaurralde, R Cesar C.

As CO{sub 2} and other greenhouse gases accumulate in the atmosphere and contribute to rising global temperatures, it is important to examine how a changing climate may affect natural and managed ecosystems. In this series of papers, we study the impacts of climate change on agriculture, water resources and natural ecosystems in the conterminous United States using a suite of climate change predictions from General Circulation Models (GCMs) as described in Part 1. Here we describe the agriculture model EPIC and the HUMUS water model and validate them with historical crop yields and streamflow data. We compare EPIC simulated grainmore » and forage crop yields with historical crop yields from the US Department of Agriculture and find an acceptable level of agreement for this study. The validation of HUMUS simulated streamflow with estimates of natural streamflow from the US Geological Survey shows that the model is able to reproduce significant relationships and capture major trends.« less

Facile and Scalable Synthesis Method for High-Quality Few-Layer Graphene through Solution-Based Exfoliation of Graphite.

PubMed

Wee, Boon-Hong; Wu, Tong-Fei; Hong, Jong-Dal

2017-02-08

Here we describe a facile and scalable method for preparing defect-free graphene sheets exfoliated from graphite using the positively charged polyelectrolyte precursor poly(p-phenylenevinylene) (PPV-pre) as a stabilizer in an aqueous solution. The graphene exfoliated by PPV-pre was apparently stabilized in the solution as a form of graphene/PPV-pre (denoted to GPPV-pre), which remains in a homogeneous dispersion over a year. The thickness values of 300 selected 76% GPPV-pre flakes ranged from 1 to 10 nm, corresponding to between one and a few layers of graphene in the lateral dimensions of 1 to 2 μm. Furthermore, this approach was expected to yield a marked decrease in the density of defects in the electronic conjugation of graphene compared to that of graphene oxide (GO) obtained by Hummers' method. The positively charged GPPV-pre was employed to fabricate a poly(ethylene terephthalate) (PET) electrode layer-by-layer with negatively charged GO, yielding (GPPV-pre/GO) n film electrode. The PPV-pre and GO in the (GPPV-pre/GO) n films were simultaneously converted using hydroiodic acid vapor to fully conjugated PPV and reduced graphene oxide (RGO), respectively. The electrical conductivity of (GPPV/RGO) 23 multilayer films was 483 S/cm, about three times greater than that of the (PPV/RGO) 23 multilayer films (166 S/cm) comprising RGO (prepared by Hummers method). Furthermore, the superior electrical properties of GPPV were made evident, when comparing the capacitive performances of two supercapacitor systems; (polyaniline PANi/RGO) 30 /(GPPV/RGO) 23 /PET (volumetric capacitance = 216 F/cm 3 ; energy density = 19 mWh/cm 3 ; maximum power density = 498 W/cm 3 ) and (PANi/RGO) 30 /(PPV/RGO) 23 /PET (152 F/cm 3 ; 9 mWh/cm 3 ; 80 W/cm 3 ).

Monitoring of active layer thermal regime and depth on CALM-S site, James Ross Island, Eastern Antarctic Peninsula

NASA Astrophysics Data System (ADS)

Hrbáček, Filip; Kňažková, Michaela; Nývlt, Daniel; Láska, Kamil; Mueller, Carsten W.; Ondruch, Jakub

2017-04-01

Active layer thickness and its dynamic are considered one of the key parameters of permafrost-affected ground. They variability are very sensitive to specific local conditions, especially climate, vegetation, snow cover or soil texture and moisture. To better understand the local variability of active layer thickness in Antarctica, the original Circumpolar Active Layer Monitoring protocol (CALM) was adapted as its southern form (CALM-S) with respect to specific conditions of Antarctica. To date, almost 40 CALM-S sites were registered across the Antarctic continent with the highest density on western Antarctic Peninsula (South Shetlands) and Victoria Land in East Antarctica (McMurdo region). On James Ross Island, CALM-S site was established in February 2014 as the first CALM-S in the eastern Antarctic Peninsula region. The CALM-S site is located near the Johann Gregor Mendel Station on the northern coast of James Ross Island. The area delimited to 80 × 70 m is elevated at 8 to 11 m asl. Geologically it consists of a Holocene marine terrace ( 80% of CALM-S area) with typical sandy material and passes to lithified to poorly disintegrated sedimentary rocks of Cretaceous Whisky Bay Formation ( 20% of CALM-S area) with a more muddy material and a typical bimodal composition. For both geologically different parts of CALM-S site, ground temperature was measured at two profiles at several levels up to 200 cm depth using resistance thermometers Pt100/8 (accuracy ± 0.15 °C). The air temperature at 2 m above surface was monitored at the automatic weather station near Johann Gregor Mendel Station using resistance thermometer Pt100/A (accuracy ± 0.15 °C). Data used in this study were obtained during the period from 1 March 2013 to 6 February 2016. Mechanical probing of active layer depth was performed in 72 grid points at the end of January, or beginning of February in 2014 to 2016. During the whole study period, mean annual air temperature varied between -7.0 °C (2013) and -6.7 °C (2015), while the mean annual ground temperature at 5 cm ranged from -5.6 °C (2013) to -5.3 °C (2014). Thawing season started in mid-November between 17th (2013/14) and 24th (2014/15) and ended at the end of February (22nd in 2014/15) and beginning of March (7th in 2013/14). The maximum active layer thickness determined from 0°C isotherm varied from 86 to 87 cm at profile 1, while it reached only 51 to 65 cm at profile 2. The mean probed active layer depth varied between 66 cm (2013/4) and 78 cm (2014/15). The maximum probed active layer depth increased from 100 cm in 2014 to 113 cm in 2016. High variability of active layer depth across CALM-S site was caused by different ground thermal properties of Holocene marine terrace sand and Cretaceous clayey sandstones. These results differ significantly from another CALM-S sites in Antarctica, where the main factors affecting thawing depth variability were snow cover and topography. These results confirmed previous observation from James Ross Island, where variability of active layer depth was related primarily to different ground properties (texture, moisture, physical characteristic) then local climate or snow cover.

Microeukaryotic diversity in marine environments, an analysis of surface layer sediments from the East Sea.

PubMed

Park, Soo-Je; Park, Byoung-Joon; Pham, Vinh Hoa; Yoon, Dae-No; Kim, Si-Kwan; Rhee, Sung-Keun

2008-06-01

Molecular techniques, based on clone library of 18S rRNA gene, were employed to ascertain the diversity of microeukaryotic organisms in sediments from the East Sea. A total of 261 clones were recovered from surface sediments. Most of the clone sequences (90%) were affiliated with protists, dominated by Ciliates (18%) and Dinoflagellates (19%) of Alveolates, phototrophic Stramenopiles (11%), and Cercozoa (20%). Many of the clones were related to uncultivated eukaryotes clones retrieved from anoxic environments with several highly divergent 18S rRNA gene sequences. However, no clones were related to cultivated obligate anaerobic protists. Protistan communities between subsurface layers of 1 and 9 cm shared 23% of total phylotypes which comprised 64% of total clones retrieved. Analysis of diversity indices and rarefaction curve showed that the protistan community within the 1 cm layer exhibited higher diversity than the 9 cm layer. Our results imply that diverse protists remain to be uncovered within marine benthic environments.

Zirconium oxide surface passivation of crystalline silicon

NASA Astrophysics Data System (ADS)

Wan, Yimao; Bullock, James; Hettick, Mark; Xu, Zhaoran; Yan, Di; Peng, Jun; Javey, Ali; Cuevas, Andres

2018-05-01

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited zirconium oxide (ZrOx). The optimum layer thickness and activation annealing conditions are determined to be 20 nm and 300 °C for 20 min. Cross-sectional transmission electron microscopy imaging shows an approximately 1.6 nm thick SiOx interfacial layer underneath an 18 nm ZrOx layer, consistent with ellipsometry measurements (˜20 nm). Capacitance-voltage measurements show that the annealed ZrOx film features a low interface defect density of 1.0 × 1011 cm-2 eV-1 and a low negative film charge density of -6 × 1010 cm-2. Effective lifetimes of 673 μs and 1.1 ms are achieved on p-type and n-type 1 Ω cm undiffused c-Si wafers, respectively, corresponding to an implied open circuit voltage above 720 mV in both cases. The results demonstrate that surface passivation quality provided by ALD ZrOx is consistent with the requirements of high efficiency silicon solar cells.

Ground-layer plant community responses to even-age and uneven-age silvicultural treatments in Wisconsin northern hardwood forests

Treesearch

Cristel C. Kern; Brian J. Palik; Terry F. Strong

2006-01-01

We evaluated ground-layer plant diversity and community composition in northern hardwood forests among uncut controls and stands managed with even-age or uneven-age silvicultural systems. Even-age treatments included diameter-limit cuttings (20-cm diameter at 30-cm stem height) in 1952 and shelterwood removals in 1964. Uneven-age treatments included three intensities...

Rational Water and Nitrogen Management Improves Root Growth, Increases Yield and Maintains Water Use Efficiency of Cotton under Mulch Drip Irrigation

PubMed Central

Zhang, Hongzhi; Khan, Aziz; Tan, Daniel K. Y.; Luo, Honghai

2017-01-01

There is a need to optimize water-nitrogen (N) applications to increase seed cotton yield and water use efficiency (WUE) under a mulch drip irrigation system. This study evaluated the effects of four water regimes [moderate drip irrigation from the third-leaf to the boll-opening stage (W1), deficit drip irrigation from the third-leaf to the flowering stage and sufficient drip irrigation thereafter (W2), pre-sowing and moderate drip irrigation from the third-leaf to the boll-opening stage (W3), pre-sowing and deficit drip irrigation from the third-leaf to the flowering stage and sufficient drip irrigation thereafter (W4)] and N fertilizer at a rate of 520 kg ha-1 in two dressing ratios [7:3 (N1), 2:8 (N2)] on cotton root morpho-physiological attributes, yield, WUE and the relationship between root distribution and dry matter production. Previous investigations have shown a strong correlation between root activity and water consumption in the 40–120 cm soil layer. The W3 and especially W4 treatments significantly increased root length density (RLD), root volume density (RVD), root mass density (RMD), and root activity in the 40–120 cm soil layer. Cotton RLD, RVD, RMD was decreased by 13.1, 13.3, and 20.8%, respectively, in N2 compared with N1 at 70 days after planting (DAP) in the 0–40 cm soil layer. However, root activity in the 40–120 cm soil layer at 140 DAP was 31.6% higher in N2 than that in N1. Total RMD, RLD and root activity in the 40–120 cm soil were significantly and positively correlated with shoot dry weight. RLD and root activity in the 40–120 cm soil layer was highest in the W4N2 treatments. Therefore increased water consumption in the deep soil layers resulted in increased shoot dry weight, seed cotton yield and WUE. Our data can be used to develop a water-N management strategy for optimal cotton yield and high WUE. PMID:28611817

Reducing the contact resistance in bottom-contact-type organic field-effect transitors using an AgO x interface layer

NASA Astrophysics Data System (ADS)

Minagawa, Masahiro; Kim, Yeongin; Claus, Martin; Bao, Zhenan

2017-09-01

Bottom-contact organic field-effect transistors (OFETs) are prepared by inserting an AgO x layer between a pentacene layer and the source-drain electrodes. The contact resistance in the device is ˜8.1 kΩ·cm with an AgO x layer oxidized for 60 s but reaches 116.9 kΩ·cm with a non-oxidized Ag electrode. The drain current and mobility in the OFETs with the AgO x layer increase with the oxidization time and then gradually plateau, and this trend strongly depends on the work function of the Ag surface. Further, the hole injection is enhanced by the presence of Ag2O but inhibited by the presence of AgO.

Thermal regime of active layer at two lithologically contrasting sites on James Ross Island, Antarctic Peninsula.

NASA Astrophysics Data System (ADS)

Hrbáček, Filip; Nývlt, Daniel; Láska, Kamil

2016-04-01

Antarctic Peninsula region (AP) represents one of the most rapidly warming parts of our planet in the last 50 years. Despite increasing research activities along both western and eastern sides of AP in last decades, there is still a lot of gaps in our knowledge relating to permafrost, active layer and its thermal and physical properties. This study brings new results of active layer monitoring on James Ross Island, which is the largest island in northern AP. Its northern part, Ulu Peninsula, is the largest ice-free area (more than 200 km2) in the region. Due its large area, we focused this study on sites located in different lithologies, which would affect local thermal regime of active layer. Study site (1) at Abernethy Flats area (41 m a.s.l.) lies ~7 km from northern coast. Lithologically is formed by disintegrated Cretaceous calcareous sandstones and siltstones of the Santa Marta Formation. Study site (2) is located at the northern slopes of Berry Hill (56 m a.s.l.), about 0.4 km from northern coastline. Lithology is composed of muddy to intermediate diamictites, tuffaceous siltstones to fine grained sandstones of the Mendel Formation. Data of air temperature at 2 meters above ground and the active layer temperatures at 75 cm deep profiles were obtained from both sites in period 1 January 2012 to 31 December 2014. Small differences were found when comparing mean air temperatures and active temperatures at 5 and 75 cm depth in the period 2012-2014. While the mean air temperatures varied between -7.7 °C and -7.0 °C, the mean ground temperatures fluctuated between -6.6 °C and -6.1 °C at 5 cm and -6.9 °C and -6.0 °C at 75 cm at Abernethy Flats and Berry Hill slopes respectively. Even though ground temperature differences along the profiles weren't pronounced during thawing seasons, the maximum active layer thickness was significantly larger at Berry Hill slopes (80 to 82 cm) than at Abernethy Flats (52 to 64 cm). We assume this differences are affected by local lithology, especially by the higher proportion of fine particles and more thermally conductive minerals, together with higher water saturation are fundamental for higher maximum active layer thickness found at Berry Hill slopes.

[Soil moisture variation under different water and fertilization managements in apple orchard of Weibei dryland, China].

PubMed

Zhao, Zhi Yuan; Zheng, Wei; Liu, Jie; Ma, Peng Yi; Li, Zi Yan; Zhai, Bing Nian; Wang, Zhao Hui

2018-04-01

To evaluate the variations of soil moisture under different water and fertilizer treatments in apple orchard in the Weibei dryland, a field experiment was carried out in 2013-2016 at Tianjiawa Village, Baishui County, Shaanxi Province. There were three treatments, i.e., farmers traditional model (only addition of NPK chemical fertilizer, FM), extension model (swine manure and NPK chemical fertilizer combined with black plastic film in tree row space, EM), and optimized model (swine manure and NPK chemical fertilizer combined with black plastic film in tree row space and planting rape in the inter-row of apple trees, OM). The results showed that OM treatment significantly increased soil water storage capacity in 0-200 cm soil layer. Water content of 0-100 cm soil layer was increased by 5.6% and 15.3% in the dry season compared with FM and EM treatment, respectively. Moreover, the soil water relative deficit index of OM was lower than that of EM in 200-300 cm soil layer. The rainfall infiltration in the dry year could reach 300 cm depth under OM. Meanwhile, OM stabilized soil water content and efficiently alleviated the desiccation in deep soil layer. Compared with FM and EM, the 4-year average yield of OM was increased by 36.6% and 22.5%, respectively. In summary, OM could increase water use efficiency through increasing the contents of available soil water and improving the soil water condition in shallow and deep layers, which help alleviate the soil deficit in deep layer and increase yield.

Soils characterisation along ecological forest zones in the Eastern Himalayas

NASA Astrophysics Data System (ADS)

Simon, Alois; Dhendup, Kuenzang; Bahadur Rai, Prem; Gratzer, Georg

2017-04-01

Elevational gradients are commonly used to characterise vegetation patterns and, to a lesser extent, also to describe soil development. Furthermore, interactions between vegetation cover and soil characteristics are repeatedly observed. Combining information on soil development and easily to distinguish forest zones along elevational gradients, creates an added value for forest management decisions especially in less studied mountain regions. For this purpose, soil profiles along elevational gradients in the temperate conifer forests of Western and Central Bhutan, ranging from 2600-4000m asl were investigated. Thereby, 82 soil profiles were recorded and classified according to the World Reference Base for Soil Resources. Based on 19 representative profiles, genetic horizons were sampled and analysed. We aim to provide fundamental information on forest soil characteristics along these elevational transects. The results are presented with regard to ecological forest zones. The elevational distribution of the reference soil groups showed distinct distribution ranges for most of the soils. Cambisols were the most frequently recorded reference soil group with 58% of the sampled profiles, followed by Podzols in higher elevations, and Stagnosols, at intermediate elevations. Fluvisols occurred only at the lower end of the elevational transects and Phaeozems only at drier site conditions in the cool conifer dry forest zone. The humus layer thickness differs between forest zones and show a shift towards increased organic layer (O-layer) with increasing elevation. The reduced biomass productivity with increasing elevation and subsequently lower litter input compensates for the slow decomposition rates. The increasing O-layer thickness is an indicator of restrained intermixing of organic and mineral components by soil organisms at higher elevation. Overall, the soil types and soil characteristics along the elevational gradient showed a continuous and consistent change, instead of abrupt changes. We interpret these as manifestations of changes of temperature and precipitation with elevation which also drives forest zonation in these least anthropogenically influenced forest ecosystems. The elevational distribution of forest zones is correlated with the distribution of soil types and thus also reflects soil characteristics.

Correlations between soil characteristics and radioactivity content of Vojvodina soil.

PubMed

Forkapic, S; Vasin, J; Bikit, I; Mrdja, D; Bikit, K; Milić, S

2017-01-01

During the years 2001 and 2010, the content of 238 U, 226 Ra, 232 Th, 40 K and 137 Cs in agricultural soil and soil geochemical characteristics were measured on 50 locations in Northern Province of Serbia - Vojvodina. The locations for sampling were selected so that they proportionately represent all geomorphologic units in the region. The content of clay and humus varied within wide limits depending on soil type and influence the activity concentrations of radionuclides. In this paper we analyzed correlations between radionuclides content and geochemical characteristics of the soil. Possible influence of fertilizers on 238 U content in soil was discussed. The main conclusion is that measured maximal activity concentrations for 238 U (87 Bq/kg), 226 Ra (44.7 Bq/kg), 232 Th (55.5 Bq/kg) and 137 Cs (29 Bq/kg) at 30 cm depth could not endanger the safety of food production. The process of genesis of soil and cultivation mode plays a dominant role on the characteristics of the soil. The most significant correlation was found between the activity concentrations of 40 K and clay content in agricultural soil. Copyright © 2016 Elsevier Ltd. All rights reserved.

SU-E-CAMPUS-I-01: Nanometric Organic Photovoltaic Thin Film X-Ray Detectors for Clinical KVp Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elshahat, Bassem; Gill, Hardeep; Kumar, Jayant

2014-06-15

Purpose: To fabricate and test nanometric organic photovoltaic (OPV) cells made of various active-layer/electrode thicknesses and sizes; to determine the optimal material combinations and geometries suitable for dose measurements in clinical kilovoltage x-ray beams. Methods: The OPV consisted of P3HT:PCBM photoactive materials sandwiched between aluminum and Indium Tin Oxide (ITO) electrodes. Direct conversion of xrays in the active layer composed of donor and acceptor semiconducting organic materials generated signal in photovoltaic mode (without external voltage bias). OPV cells were fabricated with different active layer thicknesses (150, 270, 370 nm) and electrode areas (0.4, 0.7, 0.9, 1.4, 2.6 cm{sup 2}). Amore » series of experiments were preformed in the energy range of 60–150 kVp. The net current per unit area (nA/cm{sup 2}) was measured using 200 mAs time-integrated beam current. Results: The net OPV current as function of beam energy (kVp) was proportional to ∼E{sup 0,4} {sup 5} when adjusted for beam output. The best combination of parameters for these cells was 270 nm active layer thicknesses for 0.7 cm{sup 2} electrode area. The measured current ranged from 0.69 to 2.43 nA/cm{sup 2} as a function of x-ray energy between 60 and 150 kVp, corresponding to 0.09 – 0.06 nA/cm{sup 2}/mGy, respectively, when adjusted for the beam output. Conclusion: The experiments indicate that OPV detectors possessing 270 nm active layer and 0.7 cm{sup 2} Al electrode areas have sensitivity by a factor of 2.5 greater than commercial aSi thin film PV. Because OPV can be made flexible and they do not require highvoltage bias supply, they open the possibility for using as in-vivo detectors in radiation safety in x-ray imaging beams.« less

Molecular beam epitaxial growth of high-quality InSb on InP and GaAs substrates

NASA Technical Reports Server (NTRS)

Oh, J. E.; Bhattacharya, P. K.; Chen, Y. C.; Tsukamoto, S.

1989-01-01

Epitaxial layers of InSb were grown on InP and GaAs substrates by molecular beam epitaxy. The dependence of the epilayer quality on flux ratio, J sub Sb4/J sub In, was studied. Deviation from an optimum value of J sub Sb4/J sub In (approx. 2) during growth led to deterioration in the surface morphology and the electrical and crystalline qualities of the films. Room temperature electron mobilities as high as 70,000 and 53,000 sq cm /V-s were measured in InSb layers grown on InP and GaAs substrates, respectively. Unlike the previous results, the conductivity in these films is n-type even at T = 13 K, and no degradation of the electron mobility due to the high density of dislocations was observed. The measured electron mobilities (and carrier concentrations) at 77 K in InSb layers grown on InP and GaAs substrates are 110,000 sq cm/V-s (3 x 10(15) cm(-3)) and 55,000 sq cm/V-s (4.95 x 10(15) cm(-3)), respectively, suggesting their application to electronic devices at cryogenic temperatures.

The effects of magnesium doping on the modal loss in AlGaN-based deep UV lasers

NASA Astrophysics Data System (ADS)

Martens, M.; Kuhn, C.; Simoneit, T.; Hagedorn, S.; Knauer, A.; Wernicke, T.; Weyers, M.; Kneissl, M.

2017-02-01

Absorption losses in the Mg-doped layers significantly contribute to the modal losses in group-III-nitride-based lasers. In this paper, we investigate the influence of Mg-doping on the modal absorption of optically pumped UVC lasers grown on epitaxially laterally overgrown AlN/sapphire substrates with an averaged threading dislocation density of 1 × 109 cm-2. By varying the setback of the Mg-doping (˜1 × 1020 cm-3) within the upper Al0.70Ga0.30N waveguide layer, the overlap of the optical mode with the Mg-doped region increases. For all structures, internal losses were derived from gain spectra obtained by the variable stripe length method. The internal losses increase from 10 cm-1 for lasers without Mg-doping to 28 cm-1 for lasers with a fully Mg-doped upper waveguide layer. The overlap of the optical mode with the Mg-doped waveguide ΓMg clearly correlates with the modal losses. This allows to calculate the Mg-induced losses in current injection laser diodes by αm o d M g = Γ M g × 50 cm - 1 .

Measured Propagation Characteristics of Finite Ground Coplanar Waveguide on Silicon with a Thick Polyimide Interface Layer

NASA Technical Reports Server (NTRS)

Ponchak, George E.; Papapolymerou, John; Tentzeris, Emmanouil M.; Williams, W. O. (Technical Monitor)

2002-01-01

Measured propagation characteristics of Finite Ground Coplanar (FGC) waveguide on silicon substrates with resistivities spanning 3 orders of magnitude (0.1 to 15.5 Ohm cm) and a 20 micron thick polyimide interface layer is presented as a function of the FGC geometry. Results show that there is an optimum FGC geometry for minimum loss, and silicon with a resistivity of 0.1 Ohm cm has greater loss than substrates with higher and lower resistivity. Lastly, substrates with a resistivity of 10 Ohm cm or greater have acceptable loss.

Functional interpretation of representative soil spatial-temporal variability at the Central region of European territory of Russia

NASA Astrophysics Data System (ADS)

Vasenev, I.

2012-04-01

The essential spatial and temporal variability is mutual feature for most natural and man-changed soils at the Central region of European territory of Russia. The original spatial heterogeneity of forest and forest-steppe soils has been further complicated by a specific land-use history and different-direction soil successions due to environmental changes and human impacts. For demand-driven land-use planning and decision making the quantitative analysis, modeling and functional-ecological interpretation of representative soil cover patterns spatial variability is an important and challenging task that receives increasing attention from scientific society, private companies, governmental and environmental bodies. On basis of long-term different-scale soil mapping, key plot investigation, land quality and land-use evaluation, soil forming and degradation processes modeling, functional-ecological typology of the zonal set of elementary soil cover patterns (ESCP) has been done in representative natural and man transformed ecosystems of the forest, forest-steppe and steppe zones at the Central region of European territory of Russia (ETR). The validation and ranging of the limiting factors of functional quality and ecological state have been made for dominating and most dynamical components of ESCP regional-typological forms - with application of local GIS, traditional regression kriging and correlation tree models. Development, zonal-regional differentiation and verification of the basic set of criteria and algorithms for logically formalized distinguishing of the most "stable" & "hot" areas in soil cover patterns make it possible for quantitative assessment of dominating in them elementary landscape, soil-forming and degradation processes. The received data essentially expand known ranges of the soil forming processes (SFP) rate «in situ». In case of mature forests mutual for them the windthrow impacts and lateral processes make SFPs more active and complex both in soils of windthrow mounds and holes: CO2 emission increases by 30-60 %; proteolytic activities - by 50-200 %, average humification rate exceeds 100-1000 g/m2year, and the rate of aggressive fulvic acid formation - 40-300 g/m2year. The average lessivage rate may reach 2-3 kg*cm/m2year and the rate of oxalate extractable Fe2O3, Al2O3migration is 0.6-1.3 kg*cm/ m2year. Eluvial horizons can go deep on 6-18 cm per 50-150 yeas - depending on depth of initial impacts and on morphogenetic profile of background soil. The carried out analysis of Chernozem regional-typological degradation processes has shown qualitative expansion of their set. The outcomes of statistical modeling show essential amplification of dehumification processes due to current violation of traditional balances of organic matter in agrolandscapes. A drop of humus content below threshold values (4.5-6.5 % for different Chernozems) considerably reduces farming effectiveness. Mean annual rate of humus decreasing and increasing varies from 0.1 up to 1.3 g/kg per year, acidification and alkalization - from 0.01 up to 0.13 dp per year, salinity - from 5 up to 18 mg/kg per year. Succession analysis of modern evolution of natural and man-changed soils essentially increases accuracy of quantitative assessments of dominant SFPs' rate and potential, their influence on landscape and soil cover quality and diversity. Their results allow developing the regional and landscape adapted versions of automated systems of land agroecological evaluation (RASLEV) and demand-driven land-use DSS (LODSSAL).

Improved Mobility and Bias Stability of Thin Film Transistors Using the Double-Layer a-InGaZnO/a-InGaZnO:N Channel.

PubMed

Yu, H; Zhang, L; Li, X H; Xu, H Y; Liu, Y C

2016-04-01

The amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) were demonstrated based on a double-layer channel structure, where the channel is composed of an ultrathin nitro-genated a-IGZO (a-IGZO:N) layer and an undoped a-IGZO layer. The double-layer channel device showed higher saturation mobility and lower threshold-voltage shift (5.74 cm2/Vs, 2.6 V) compared to its single-layer counterpart (0.17 cm2/Vs, 7.23 V). The improvement can be attributed to three aspects: (1) improved carrier transport properties of the channel by the a-IGZO:N layer with high carrier mobility and the a-IGZO layer with high carrier concentration, (2) reduced interfacial trap density between the active channel and the gate insulator, and (3) higher surface flatness of the double-layer channel. Our study reveals key insights into double-layer channel, involving selecting more suitable electrical property for back-channel layer and more suitable interface modification for active layer. Meanwhile, room temperature fabrication amorphous TFTs offer certain advantages on better flexibility and higher uniformity over a large area.

Improved radiation tolerance of MAPS using a depleted epitaxial layer

NASA Astrophysics Data System (ADS)

Dorokhov, A.; Bertolone, G.; Baudot, J.; Brogna, A. S.; Colledani, C.; Claus, G.; De Masi, R.; Deveaux, M.; Dozière, G.; Dulinski, W.; Fontaine, J.-C.; Goffe, M.; Himmi, A.; Hu-Guo, Ch.; Jaaskelainen, K.; Koziel, M.; Morel, F.; Santos, C.; Specht, M.; Valin, I.; Voutsinas, G.; Wagner, F. M.; Winter, M.

2010-12-01

Tracking performance of Monolithic Active Pixel Sensors (MAPS) developed at IPHC (Turchetta, et al., 2001) [1] have been extensively studied (Winter, et al., 2001; Gornushkin, et al., 2002) [2,3]. Numerous sensor prototypes, called MIMOSA, were fabricated and tested since 1999 in order to optimise the charge collection efficiency and power dissipation, to minimise the noise and to increase the readout speed. The radiation tolerance was also investigated. The highest fluence tolerable for a 10 μm pitch device was found to be ˜1013 neq/cm2, while it was only 2×1012 neq/cm2 for a 20 μm pitch device. The purpose of this paper is to show that the tolerance to non-ionising radiation may be extended up to O(10 14) n eq/cm 2. This goal relies on a fabrication process featuring a 15 μm thin, high resistivity ( ˜1 kΩ cm) epitaxial layer. A sensor prototype (MIMOSA-25) was fabricated in this process to explore its detection performance. The depletion depth of the epitaxial layer at standard CMOS voltages ( <5 V) is similar to the layer thickness. Measurements with m.i.p.s show that the charge collected in the seed pixel is at least twice larger for the depleted epitaxial layer than for the undepleted one, translating into a signal-to-noise ratio (SNR) of ˜50. Tests after irradiation have shown that this excellent performance is maintained up to the highest fluence considered ( 3×1013 neq/cm2), making evidence of a significant extension of the radiation tolerance limits of MAPS. Standing for minimum ionising particle.

Effective anomalous Hall coefficient in an ultrathin Co layer sandwiched by Pt layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Peng; Wu, Di; Jiang, Zhengsheng

2014-02-14

Anomalous Hall effect in Co/Pt multilayer is important to study the effect of interface with strong spin-orbit coupling. However, the shunting effect of the layers in such system and the circuit in the plane perpendicular to the injected current were overlooked in most works and thus, anomalous Hall coefficient in Co/Pt multilayer has not been determined accurately. Considering the shunting effect and the equivalent circuit, we show that the effective anomalous Hall coefficient of a 0.5 nm thick Co layer sandwiched by Pt layers R{sub S} is 0.29 ± 0.01 μΩ cm/T at the zero temperature limit and increases to about 0.73 μΩ cm/T at the temperaturemore » of 300 K. R{sub S} is one order larger than that in bulk Co film, indicating the large contribution of the Co/Pt interface. R{sub S} increases with the resistivity of Co as well as a resistivity independent contribution of −0.23 ± 0.01 μΩ cm/T. The equivalent anomalous Hall current in the Co layer has a maximum of 1.1% of the injected transverse current in the Co layer around the temperature of 80 K.« less

High-performance a-IGZO thin-film transistor with conductive indium-tin-oxide buried layer

NASA Astrophysics Data System (ADS)

Ahn, Min-Ju; Cho, Won-Ju

2017-10-01

In this study, we fabricated top-contact top-gate (TCTG) structure of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with a thin buried conductive indium-tin oxide (ITO) layer. The electrical performance of a-IGZO TFTs was improved by inserting an ITO buried layer under the IGZO channel. Also, the effect of the buried layer's length on the electrical characteristics of a-IGZO TFTs was investigated. The electrical performance of the transistors improved with increasing the buried layer's length: a large on/off current ratio of 1.1×107, a high field-effect mobility of 35.6 cm2/Vs, a small subthreshold slope of 116.1 mV/dec, and a low interface trap density of 4.2×1011 cm-2eV-1 were obtained. The buried layer a-IGZO TFTs exhibited enhanced transistor performance and excellent stability against the gate bias stress.

The effect of annealing on the MR and exchange bias characteristics in dual spin valve with nano-oxide layer

NASA Astrophysics Data System (ADS)

Jang, S. H.; Kang, T.; Kim, H. J.; Kim, K. Y.

2002-02-01

We investigated magnetoresistance (MR) and exchange bias properties by annealing in the dual spin valve (SV) with nano-oxide layer (NOL). By analyzing effects of NOL in top and bottom pinned simple SVs, MR enhancement effect of NOL inserted in the bottom pinned layer was higher than that of NOL in the top pinned layer with annealing. By the enhanced specular scattering of electrons by NOL, the MR ratio of dual SV with NOL was increased to 15.5-15.9% with an annealing of 200-250°C. Exchange coupling constant Jex was improved rapidly as 0.13-0.16 erg/cm 2 by annealing in the bottom pinned layer, whereas the effect of annealing was not large in the top pinned layer with Jex of about 0.09-0.116 erg/cm 2.

The reduction of critical H implantation dose for ion cut by incorporating B-doped SiGe/Si superlattice into Si substrate

NASA Astrophysics Data System (ADS)

Xue, Zhongying; Chen, Da; Jia, Pengfei; Wei, Xing; Di, Zengfeng; Zhang, Miao

2016-11-01

An approach to achieve Si or SiGe film exfoliation with as low as 3 × 1016/cm2 H implantation dose was investigated. Two intrinsic Si0.75Ge0.25/Si samples, merged with B-doped Si0.75Ge0.25 layer and B-doped Si0.75Ge0.25/Si superlattice (SL) layer respectively, were used to study the formation of crack after 3 × 1016/cm2 H implantation and annealing. For the sample into which B doped Si0.75Ge0.25 layer is incorporated, only few discrete cracks are observed along both sides of the B doped Si0.75Ge0.25 layer; on the contrary, a continuous (100) oriented crack is formed in the B-doped Si0.75Ge0.25/Si SL layer, which means ion cut can be achieved using this material with 3 × 1016/cm2 H implantation. As the SIMS profiles confirm that hydrogen tends to be trapped at B-doped SiGe/Si interface, the formation of continuous crack in SL layer can be ascribed to the more efficient hydrogen trapping by the multiple B-doped SiGe/Si interfaces.

[Effects of mulching management on biomass of Phyllostachys praecox and soil fertility].

PubMed

Zhai, Wan Lu; Yang, Chuan Bao; Zhang, Xiao Ping; Gao, Gui Bin; Zhong, Zhe Ke

2018-04-01

We analyzed the dynamics of stand growth and soil nutrient availability during the degradation processes of Phyllostachys praecox plantation, taking the advantage of bamboo forest stands with different mulching ages (0, 3, 6, 9 and 12 a). The results showed the aboveground and belowground biomass of bamboo forest reached the maximum value when they were covered by three years, which was significantly increased by 14.6% and 146.6% compared with the control. The soil nutrient content was affected by the mulching age and soil layer. Soil nutrients gradually accumulated in upper layer. Soil organic carbon and total nitrogen content were increased with the increases of coverage years. The soil total phosphorus content at different soil layers showed a trend of decreasing first and then increasing. It was the lowest level in the surface layer (0-20 cm) and the bottom (40-60 cm) in 6 years, and the subsurface (20-40 cm) soil reached the lowest level in three years. The total potassium content kept increasing in 0-20 cm soil layer, but decreased during the first three years of mulching and then increased in 20-60 cm soil layer. The comprehensive index of soil fertility quality was greatly improved after nine years mulching, with fertility of subsurface soil being better than that of surface and bottom soils. There was no relationship between the soil fertility index and biomass of different organs in bamboo in the different mulching ages. In the subsurface, however, nitrogen content was negatively related to leaf biomass and potassium was negatively correlated with the biomass of leaves and whip roots. Our results indicated that excessive accumulation of soil nutrients seriously inhibited the propagation and biomass accumulation of P. praecox after long-term mulching management and a large amount of fertilizer, which further aggravated the degradation of bamboo plantation.

Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

NASA Astrophysics Data System (ADS)

Bakhsheshi-Rad, H. R.; Hamzah, E.; Bagheriyan, S.; Daroonparvar, M.; Kasiri-Asgarani, M.; Shah, A. M.; Medraj, M.

2016-09-01

A triplex plasma (NiCoCrAlHfYSi/Al2O3·13%TiO2)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al2O3·13%TiO2 coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density ( i corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.

Fabrication of 4H-SiC lateral double implanted MOSFET on an on-axis semi-insulating substrate without using epi-layer

NASA Astrophysics Data System (ADS)

Kim, Hyoung Woo; Seok, Ogyun; Moon, Jeong Hyun; Bahng, Wook; Jo, Jungyol

2017-12-01

4H-SiC lateral double implanted metal-oxide-semiconductor field effect transistors (LDIMOSFET) were fabricated on on-axis semi-insulating SiC substrates without using an epi-layer. The LDIMOSFET adopted a current path layer (CPL), which was formed by ion-implantation. The CPL works as a drift region between gate and drain. By using on-axis semi-insulating substrate and optimized CPL parameters, breakdown voltage (BV) of 1093 V and specific on-resistance (R on,sp) of 89.8 mΩ·cm2 were obtained in devices with 20 µm long CPL. Experimentally extracted field-effect channel mobility was 21.7 cm2·V-1·s-1 and the figure-of-merit (BV2/R on,sp) was 13.3 MW/cm2.

Metal-oxide-semiconductor devices using Ga2O3 dielectrics on n-type GaN

NASA Astrophysics Data System (ADS)

Lee, Ching-Ting; Chen, Hong-Wei; Lee, Hsin-Ying

2003-06-01

Using a photoelectrochemical method involving a He-Cd laser, Ga2O3 oxide layers were directly grown on n-type GaN. We demonstrated the performance of the resultant metal-oxide-semiconductor devices based on the grown Ga2O3 layer. An extremely low reverse leakage current of 200 pA was achieved when devices operated at -20 V. Furthermore, high forward and reverse breakdown electric fields of 2.80 MV/cm and 5.70 MV/cm, respectively, were obtained. Using a photoassisted current-voltage method, a low interface state density of 2.53×1011 cm-2 eV-1 was estimated. The varactor devices permit formation of inversion layers, so that they may be applied for the fabrication of metal-oxide-semiconductor field-effect transistors.

Representation of Dissolved Organic Carbon in the JULES Dynamic Global Vegetation Model

NASA Astrophysics Data System (ADS)

Nakhavali, Mahdi; Friedlingstein, Pierre; Guenet, Bertrand; Ciais, Philip

2017-04-01

Current global models of the carbon cycle consider only vertical gas exchanges between terrestrial or oceanic reservoirs and the atmosphere, hence not considering lateral transport of carbon from the continent to the oceans. This also means that such models implicitly consider that all the CO2 which is not respired to the atmosphere is stored on land, hence overestimating the land sink of carbon. Moving toward a boundless carbon cycle that is integrating the whole continuum from land to ocean to atmosphere is needed in order to better understand Earth's carbon cycle and to make more reliable projection of its future. Here we present an original representation of Dissolved Organic Carbon (DOC) processes in the Joint UK Land Environment Simulator (JULES). The standard version of JULES represent energy, water and carbon cycles and exchanges with the atmosphere, but only account for water run-off, not including export of carbon from terrestrial ecosystems to the aquatic environments. The aim of the project is to include in JULES a representation of DOC production in terrestrial soils, due to incomplete decomposition of organic matter, its decomposition to the atmosphere, and its export to the river network by leaching. In new developed version of JULES (JULES-DOCM), DOC pools, based on their decomposition rate, are classified into labile and recalcitrant within 3 meters of soil. Based on turnover rate, DOC coming from plant material pools and microbial biomass is directed to labile pool, while DOC from humus is directed to recalcitrant pool. Both of these pools have free (dissolved) and locked (adsorbed) form where just the free pool is subjected to decomposition and leaching. DOC production and decomposition are controlled by rate modifiers (moisture, temperature, vegetation fraction and decomposition rate) at each soil layer. Decomposed DOC is released to the atmosphere following a fixed carbon use efficiency. Leaching accounts for both surface (runoff) and subsurface (groundwater) components and is parameterized as Top soil leaching (from top 20cm) and Bottom soil leaching (down to 3 meters) depending on DOC concentration and runoff leaving that layer. The model parameters are calibrated against specific sites (Brasschaat, Hainich and Carlow) for which observations of DOC concentration and leaching are available. Tuning is performed optimizing parameters such as DOC labile and recalcitrant resident time, DOC vertical distribution and CUE. Once this calibration has been performed at the site level, the model is used for global simulations with the major historical forcing (climate, atmospheric CO2 and land-use changes) in order to estimate the changes of DOC export and their attribution to anthropogenic activities.

40 CFR 192.12 - Standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... level by more than— (1) 5 pCi/g, averaged over the first 15 cm of soil below the surface, and (2) 15 pCi/g, averaged over 15 cm thick layers of soil more than 15 cm below the surface. (b) In any occupied...

40 CFR 192.12 - Standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... level by more than— (1) 5 pCi/g, averaged over the first 15 cm of soil below the surface, and (2) 15 pCi/g, averaged over 15 cm thick layers of soil more than 15 cm below the surface. (b) In any occupied...

40 CFR 192.12 - Standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... level by more than— (1) 5 pCi/g, averaged over the first 15 cm of soil below the surface, and (2) 15 pCi/g, averaged over 15 cm thick layers of soil more than 15 cm below the surface. (b) In any occupied...

40 CFR 192.12 - Standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... level by more than— (1) 5 pCi/g, averaged over the first 15 cm of soil below the surface, and (2) 15 pCi/g, averaged over 15 cm thick layers of soil more than 15 cm below the surface. (b) In any occupied...

40 CFR 192.12 - Standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... level by more than— (1) 5 pCi/g, averaged over the first 15 cm of soil below the surface, and (2) 15 pCi/g, averaged over 15 cm thick layers of soil more than 15 cm below the surface. (b) In any occupied...

Assessment of the growth/etch back technique for the production of Ge strain-relaxed buffers on Si

NASA Astrophysics Data System (ADS)

Hartmann, J. M.; Aubin, J.

2018-04-01

Thick Ge layers grown on Si(0 0 1) are handy for the production of GeOI wafers, as templates for the epitaxy of III-V and GeSn-based heterostructures and so on. Perfecting their crystalline quality would enable to fabricate suspended Ge micro-bridges with extremely high levels of tensile strain (for mid IR lasers). In this study, we have used a low temperature (400 °C)/high temperature (750 °C) approach to deposit with GeH4 various thickness Ge layers in the 0.5 μm - 5 μm range. They were submitted afterwards to short duration thermal cycling under H2 (in between 750 °C and 875-890 °C) to lower the Threading Dislocation Density (TDD). Some of the thickest layers were partly etched at 750 °C with gaseous HCl to recover wafer bows compatible with device processing later on. X-ray Diffraction (XRD) showed that the layers were slightly tensile-strained, with a 104.5-105.5% degree of strain relaxation irrespective of the thickness. The surface was cross-hatched, with a roughness slightly decreasing with the thickness, from 2.0 down to 0.8 nm. The TDD (from Omega scans in XRD) decreased from 8 × 107 cm-2 down to 107 cm-2 as the Ge layer thickness increased from 0.5 up to 5 μm. The lack of improvement when growing 5 μm thick layers then etching a fraction of them with HCl over same thickness layers grown in a single run was at variance with Thin Solid Films 520, 3216 (2012). Low temperature HCl defect decoration confirmed those findings, with (i) a TDD decreasing from slightly more 107 cm-2 down to 5 × 106 cm-2 as the Ge layer thickness increased from 1.3 up to 5 μm and (ii) no TDD hysteresis between growth and growth then HCl etch-back.

The deep layer of the tractus iliotibialis and its relevance when using the direct anterior approach in total hip arthroplasty: a cadaver study.

PubMed

Putzer, David; Haselbacher, Matthias; Hörmann, Romed; Klima, Günter; Nogler, Michael

2017-12-01

Surgical approaches through smaller incisions reveal less of the underlying anatomy, and therefore, detailed knowledge of the local anatomy and its variations is important in minimally invasive surgery. The aim of this study was to determine the location, extension, and histomorphology of the deep layer of the iliotibial band during minimally invasive hip surgery using the direct anterior approach (DAA). The morphology of the iliotibial tract was determined in this cadaver study on 40 hips with reference to the anterior superior iliac spine and the tibia. The deep layer of the tractus iliotibialis was exposed up to the hip-joint capsule and length and width measurements taken. Sections of the profound iliotibial tract were removed from the hips and the thickness of the sections was determined microscopically after staining. The superficial tractus iliotibialis had a length of 50.1 (SD 3.8) cm, while tensor fasciae latae total length was 18 (SD 2) cm [unattached 15 (SD 2.5) cm]. Length and width of the deep layer of the tractus iliotibialis were 10.4 (SD 1.3) × 3.3 (SD 0.6) cm. The deep iliotibial band always extended from the distal part of the tensor fascia latae (TFL) muscle to the lateral part of the hip capsule (mean maximum thickness 584 μm). Tractus iliotibialis deep layer morphology did not correlate to other measurements taken (body length, thigh length, and TFL length). The length of the deep layer is dependent on the TFL, since the profound part of the iliotibial band reaches from the TFL to the hip-joint capsule. The deep layer covers the hip-joint capsule, rectus, and lateral vastus muscles in the DAA interval. To access the precapsular fat pad and the hip-joint capsule, the deep layer has to be split in all approaches that use the direct anterior interval.

Microbial community structure and diversity in a municipal solid waste landfill.

PubMed

Wang, Xiaolin; Cao, Aixin; Zhao, Guozhu; Zhou, Chuanbin; Xu, Rui

2017-08-01

Municipal solid waste (MSW) landfills are the most prevalent waste disposal method and constitute one of the largest sources of anthropogenic methane emissions in the world. Microbial activities in disposed waste play a crucial role in greenhouse gas emissions; however, only a few studies have examined metagenomic microbial profiles in landfills. Here, the MiSeq high-throughput sequencing method was applied for the first time to examine microbial diversity of the cover soil and stored waste located at different depths (0-150cm) in a typical MSW landfill in Yangzhou City, East China. The abundance of microorganisms in the cover soil (0-30cm) was the lowest among all samples, whereas that in stored waste decreased from the top to the middle layer (30-90cm) and then increased from the middle to the bottom layer (90-150cm). In total, 14 phyla and 18 genera were found in the landfill. A microbial diversity analysis showed that Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phyla, whereas Halanaerobium, Methylohalobius, Syntrophomonas, Fastidiosipila, and Spirochaeta were the dominant genera. Methylohalobius (methanotrophs) was more abundant in the cover layers of soil than in stored waste, whereas Syntrophomonas and Fastidiosipila, which affect methane production, were more abundant in the middle to bottom layers (90-150cm) in stored waste. A canonical correlation analysis showed that microbial diversity in the landfill was most strongly correlated with the conductivity, organic matter, and moisture content of the stored waste. Copyright © 2017 Elsevier Ltd. All rights reserved.

Clustering of gold particles in Au implanted CrN thin films: The effect on the SPR peak position

NASA Astrophysics Data System (ADS)

Novaković, M.; Popović, M.; Schmidt, E.; Mitrić, M.; Bibić, N.; Rakočević, Z.; Ronning, C.

2017-12-01

We report on the formation of gold particles in 280 nm thin polycrystalline CrN layers caused by Au+ ion implantation. The CrN layers were deposited at 150 °C by d.c. reactive sputtering on Si(100) wafers and then implanted at room temperature with 150 keV Au+ ions to fluences of 2 × 1016 cm-2 to 4.1 × 1016 cm-2. The implanted layers were analysed by the means of Rutherford backscattering spectrometry, X-ray diffraction, atomic force microscopy and spectroscopic ellipsometry measurements. The results revealed that the Au atoms are situated in the near-surface region of the implanted CrN layers. At the fluence of 2 × 1016 cm-2 the formation of Au particles of ∼200 nm in diameter has been observed. With increasing Au ion fluence the particles coalesce into clusters with dimensions of ∼1.7 μm. The synthesized particles show a strong absorption peak associated with the excitation of surface plasmon resonances (SPR). The position of the SPR peak shifted in the range of 426.8-690.5 nm when the Au+ ion fluence was varied from 2 × 1016 cm-2 to 4.1 × 1016 cm-2. A correlation of the shift in the peak wavelength caused by the change in the particles size and clustering has been revealed, suggesting that the interaction between Au particles dominate the surface plasmon resonance effect.

[Effects of simulated nitrogen deposition on soil microbial biomass carbon and nitrogen in natural evergreen broad-leaved forest in the Rainy Area of West China].

PubMed

Zhou, Shi Xing; Zou, Cheng; Xiao, Yong Xiang; Xiang, Yuan Bin; Han, Bo Han; Tang, Jian Dong; Luo, Chao; Huang, Cong de

2017-01-01

To understand the effects of increasing nitrogen deposition on soil microbial biomass carbon (MBC) and nitrogen(MBN), an in situ experiment was conducted in a natural evergreen broad-leaved forest in Ya'an City, Sichuan Province. Four levels of nitrogen deposition were set: i.e., control (CK, 0 g N·m -2 ·a -1 ), low nitrogen (L, 5 g N·m -2 ·a -1 ), medium nitrogen (M, 15 g N·m -2 ·a -1 ), and high nitrogen (H, 30 g N·m -2 ·a -1 ). The results indicated that nitrogen deposition significantly decreased MBC and MBN in the 0-10 cm soil layer, and as N de-position increased, the inhibition effect was enhanced. L and M treatments had no significant effect on MBC and MBN in the 10-20 cm soil layer, while H treatment significantly reduced. The influence of N deposition on MBC and MBN was weakened with the increase of soil depth. MBC and MBN had obvious seasonal dynamic, which were highest in autumn and lowest in summer both in the 0-10 and 10-20 cm soil layers. The fluctuation ranges of soil microbial biomass C/N were respectively 10.58-11.19 and 9.62-12.20 in the 0-10 cm and 10-20 cm soil layers, which indicated that the fungi hold advantage in the soil microbial community in this natural evergreen broad-leaved forest.

Comparison and characterization of different tunnel layers, suitable for passivated contact formation

NASA Astrophysics Data System (ADS)

Ling, Zhi Peng; Xin, Zheng; Ke, Cangming; Jammaal Buatis, Kitz; Duttagupta, Shubham; Lee, Jae Sung; Lai, Archon; Hsu, Adam; Rostan, Johannes; Stangl, Rolf

2017-08-01

Passivated contacts for solar cells can be realized using a variety of differently formed ultra-thin tunnel oxide layers. Assessing their interface properties is important for optimization purposes. In this work, we demonstrate the ability to measure the interface defect density distribution D it(E) and the fixed interface charge density Q f for ultra-thin passivation layers operating within the tunnel regime (<2 nm). Various promising tunnel layer candidates [i.e., wet chemically formed SiO x , UV photo-oxidized SiO x , and atomic layer deposited (ALD) AlO x ] are investigated for their potential application forming electron or hole selective tunnel layer passivated contacts. In particular, ALD AlO x is identified as a promising tunnel layer candidate for hole-extracting passivated contact formation, stemming from its high (negative) fixed interface charge density in the order of -6 × 1012 cm-2. This is an order of magnitude higher compared to wet chemically or UV photo-oxidized formed silicon oxide tunnel layers, while keeping the density of interface defect states D it at a similar level (in the order of ˜2 × 1012 cm-2 eV-1). This leads to additional field effect passivation and therefore to significantly higher measured effective carrier lifetimes (˜2 orders of magnitude). A surface recombination velocity of ˜40 cm/s has been achieved for a 1.5 nm thin ALD AlO x tunnel layer prior to capping by an additional hole transport material, like p-doped poly-Si or PEDOT:PSS.

Engineering of electric field distribution in GaN(cap)/AlGaN/GaN heterostructures: theoretical and experimental studies

NASA Astrophysics Data System (ADS)

Gladysiewicz, M.; Janicki, L.; Misiewicz, J.; Sobanska, M.; Klosek, K.; Zytkiewicz, Z. R.; Kudrawiec, R.

2016-09-01

Polarization engineering of GaN-based heterostructures opens a way to develop advanced transistor heterostructures, although measurement of the electric field in such heterostructures is not a simple task. In this work, contactless electroreflectance (CER) spectroscopy has been applied to measure the electric field in GaN-based heterostructures. For a set of GaN(d  =  0, 5, 15, and 30 nm)/AlGaN(20 nm)/GaN(buffer) heterostructures a decrease of electric field in the GaN(cap) layer from 0.66 MV cm-1 to 0.27 MV cm-1 and an increase of the electric field in the AlGaN layer from 0.57 MV cm-1 to 0.99 MV cm-1 have been observed with the increase in the GaN(cap) thickness from 5-30 nm. For a set of GaN(20 nm)/AlGaN(d  =  10, 20, 30, and 40 nm)/GaN(buffer) heterostructures a decrease of the electric field in the AlGaN layer from 1.77 MV cm-1 to 0.64 MV cm-1 and an increase of the electric field in the GaN layer from 0.57 MV cm-1 to 0.99 MV cm-1 were observed with the increase in the AlGaN thickness from 10-40 nm. To determine the distribution of the electric field in these heterostructures the Schrödinger and Poisson equations are solved in a self-consistent manner and matched with experimental data. It is shown that the built-in electric field in the GaN(cap) and AlGaN layers obtained from measurements does not reach values of electric field resulting only from polarization effects. The measured electric fields are smaller due to a screening of polarization effects by free carriers, which are inhomogeneously distributed across the heterostructure and accumulate at interfaces. The results clearly demonstrate that CER measurements supported by theoretical calculations are able to determine the electric field distribution in GaN-based heterostructures quantitatively, which is very important for polarization engineering in this material system.

Geomicrobiology of Fe-rich crusts in Lake Superior sediment

NASA Astrophysics Data System (ADS)

Dittrich, M.; Monreau, L.; Quazi, S.; Raoof, B.; Chesnyuk, A.; Katsev, S.; Fulthorpe, R.

2012-04-01

The limnological puzzles of Lake Superior are increasingly attracting scientists, and very little is known about the sediments and their associated microflora. The sediments are organic poor (less than 5%C) and the lake is deep oligotrophic, with water temperatures at the bottom around 3C. Previous studies reveal Fe-rich layers in the sediments at multiple loccations around the lake. The origin and mechanisms of formation of this layer remain unknown. In this study we investigated geochemical and microbiological processes that may lead to the formation of a two cm thick iron layer about 10 cm below the sediment surface. Sediment cores from two stations (EM, 230m water depth and ED, 310m water depth) in the East Basin were used. We monitored oxygen and pH depth profiles with microsensors, porewater and sediment solid matter were analyzed for nutrient and metal contents. Furthermore, phosphorus and iron sequantial extractions of sediment cores have been perfomed. The total cell count was determined using DAPI epifluoresence microscopy. DNA was extracted from the sediment samples and 16S ribosonal RNA amplicons were analyzed with denaturing gradient gel electrophoresis (DGGE). For a more in depth analysis, DNA samples from 8-10 cm and 10-12 cm were sent to the Research and Testing Lab (Texas) for pyrosequencing of 16S rRNA gene amplicons amplified using barcoded universal primers 27f-519r. The scanning electron microscope (SEM) images from the iron layer 10-12cm show filaments that were encrusted with spheres ca. 20 nm in diameter. SEM observations of thin sections also indicate the presence of very fine particles showing various morphologies. Analyses of the deposit material by SEM and energy dispersive X-ray spectroscopy (EDS) indicate that bacteria cells surfaces served as nucleation surfaces for Fe-oxide formation. EDS line-scans through bacterial cells covered with precipitates reveal phosphorus and carbon peaks at interface between cell surface and Fe-particles. The cluster analysis performed on the DGGE separation of ribosomal RNA gene fragments revealed that the two iron layers were not highly similar to each other. We obtained a total of 26,062 16S rRNA gene sequence reads from the two iron layers and the layers directly above them, which were clustered into operational taxonomic units sharing 80% similarity or more. 64-70% of these clusters could not be classified below the phylum level. While the 8-10 cm sediment layers were dominated (46.5% of reads) by relatives of Paenisporosarcina, the iron layers contained far fewer gram positive organisms, far more proteobacteria, and an a high proportion of Nitrospira species which show relatively high similarity to organisms found in an iron II rich seep.

[Effects of different irrigation treatments during heading and flowering stage on cold resis-tance, yield and physiological characteristics of late rice].

PubMed

Cao, Na; Chen, Xiao Rong; He, Hao Hua; Zhu, Chang Lan; Cai, Shuo; Xu, Tao; Xie, Heng Wang; Liu, Fang Ping

2017-12-01

Taking super hybrid rice variety 'Wufengyou T025' as test material, the effects of different irrigation methods and water layer depth on physiological characteristics and yield in double-season late rice under low temperature conditions during heading and flowering stage were investigated. Three treatments were set, i.e., draining during day and containing 4-5 cm water layer during night (H 1 ), draining during day and containing 8-10 cm water layer during night (H 2 ), and containing 8-10 cm water layer day and night (H 3 ), with the 0-1 cm water layer day and night was as the control (CK). The results showed that rice leaf temperature, soil layer temperature and canopy temperature under the different irrigation treatments were higher than that of CK, and the warming effect of treatment H 2 was the best during the low temperature period. Leaf chlorophyll content, net photosynthetic rate, transpiration rate, leaf stomatal conductance and intercellular CO 2 concentration of rice plants decreased gradually under the low temperature, while the smallest reduction occurred in H 2 . The increase ranges of malondialdehyde and proline content in H 2 were lower, while its soluble protein content was the highest compared with other irrigation treatments. The increase ranges for the activities of superoxide dismutase and peroxidase in H 2 were lower, while its decrease range for the activity of catalase was the lowest. Irrigation for heat preservation could increase the yield, and H 2 performed best. Yield of H 2 at the second sowing date in 2014 and 2015 encountering low temperature increased by 12.9% and 13.5% respectively compared to CK. The yield components including the effective panicle numbers per plant, panicle length, seed setting rate and 1000-grain mass were improved in all irrigation treatments compared to CK. Draining during day and containing 8-10 cm water layer during night (H 2 ) was the most effective agronomic measure to enhance the tolerance to low temperature during heading and flowering stage for double-season hybrid late rice.

Tunnel-injected sub 290 nm ultra-violet light emitting diodes with 2.8% external quantum efficiency

NASA Astrophysics Data System (ADS)

Zhang, Yuewei; Jamal-Eddine, Zane; Akyol, Fatih; Bajaj, Sanyam; Johnson, Jared M.; Calderon, Gabriel; Allerman, Andrew A.; Moseley, Michael W.; Armstrong, Andrew M.; Hwang, Jinwoo; Rajan, Siddharth

2018-02-01

We report on the high efficiency tunnel-injected ultraviolet light emitting diodes (UV LEDs) emitting at 287 nm. Deep UV LED performance has been limited by the severe internal light absorption in the p-type contact layers and low electrical injection efficiency due to poor p-type conduction. In this work, a polarization engineered Al0.65Ga0.35N/In0.2Ga0.8N tunnel junction layer is adopted for non-equilibrium hole injection to replace the conventionally used direct p-type contact. A reverse-graded AlGaN contact layer is further introduced to realize a low resistance contact to the top n-AlGaN layer. This led to the demonstration of a low tunnel junction resistance of 1.9 × 10-3 Ω cm2 obtained at 1 kA/cm2. Light emission at 287 nm with an on-wafer peak external quantum efficiency of 2.8% and a wall-plug efficiency of 1.1% was achieved. The measured power density at 1 kA/cm2 was 54.4 W/cm2, confirming the efficient hole injection through interband tunneling. With the benefits of the minimized internal absorption and efficient hole injection, a tunnel-injected UV LED structure could enable future high efficiency UV emitters.

A benchmark of co-flow and cyclic deposition/etch approaches for the selective epitaxial growth of tensile-strained Si:P

NASA Astrophysics Data System (ADS)

Hartmann, J. M.; Veillerot, M.; Prévitali, B.

2017-10-01

We have compared co-flow and cyclic deposition/etch processes for the selective epitaxial growth of Si:P layers. High growth rates, relatively low resistivities and significant amounts of tensile strain (up to 10 nm min-1, 0.55 mOhm cm and a strain equivalent to 1.06% of substitutional C in Si:C layers) were obtained at 700 °C, 760 Torr with a co-flow approach and a SiH2Cl2 + PH3 + HCl chemistry. This approach was successfully used to thicken the sources and drains regions of n-type fin-shaped Field Effect Transistors. Meanwhile, the (Si2H6 + PH3/HCl + GeH4) CDE process evaluated yielded at 600 °C, 80 Torr even lower resistivities (0.4 mOhm cm, typically), at the cost however of the tensile strain which was lost due to (i) the incorporation of Ge atoms (1.5%, typically) into the lattice during the selective etch steps and (ii) a reduction by a factor of two of the P atomic concentration in CDE layers compared to that in layers grown in a single step (5 × 1020 cm-3 compared to 1021 cm-3).

Concentrations of Radionuclides (226Ra, 232Th, 40K, and 137Cs) in Chernozems of Volgograd Oblast Sampled in Different Years

NASA Astrophysics Data System (ADS)

Aparin, B. F.; Mingareeva, E. V.; Sanzharova, N. I.; Sukhacheva, E. Yu.

2017-12-01

Data on the concentrations of natural (226Ra, 232Th and 40K) and artificial (137Cs) radionuclides and on the physicochemical properties of chernozems sampled in different years are presented. In 1952, upon the creation of the Penza-Kamensk state shelterbelt, three deep (up to 3 m) soil pits were examined within the former arable field under two-year-old plantations of ash and maple along the transect crossing the territory of the Beloprudskaya Experimental Station of the USSR Academy of Sciences in Volgograd oblast. The samples from these pits were included into the collection of dated soil samples of the Dokuchaev Central Soil Science Museum. Five pits were examined along the same transect in 2009: three pits under shelterbelts (analogues of the pits studied in 1952) and two pits on arable fields between the shelterbelts. In the past 57 years, certain changes took place in the soil structure, bulk density, and the content and composition of humus. The salt profile of soils changed significantly under the forests. The comparison of distribution patterns of natural soil radionuclides in 1952 and 2009 demonstrated their higher contents at the depth of 10-20 cm in 2009 (except for the western shelterbelt). Background concentrations of natural radionuclides in parent materials and relationships between their distributions and the salt profiles of soils have been determined; they are most clearly observed is the soils under shelterbelts. Insignificant contamination with 137Cs (up to 34 Bq/kg) has been found in the samples of 2009 from the upper (0-20 cm) horizon. The activity of 137Cs regularly decreases from the east to the west; the highest concentrations of this radionuclide are found in the topmost 10 cm. This allows us to suppose that 137Cs was brought with aerial dust by eastern winds, and the shelterbelts served as barriers to the wind flow.

Experimental Study of Fillets to Reduce Corner Effects in an Oblique Shock-Wave/Boundary Layer Interaction

NASA Technical Reports Server (NTRS)

Hirt, Stefanie M.

2015-01-01

A test was conducted in the 15 cm x 15 cm supersonic wind tunnel at NASA Glenn Research Center that focused on corner effects of an oblique shock-wave/boundary-layer interaction. In an attempt to control the interaction in the corner region, eight corner fillet configurations were tested. Three parameters were considered for the fillet configurations: the radius, the fillet length, and the taper length from the square corner to the fillet radius. Fillets effectively reduced the boundary-layer thickness in the corner; however, there was an associated penalty in the form of increased boundary-layer thickness at the tunnel centerline. Larger fillet radii caused greater reductions in boundary-layer thickness along the corner bisector. To a lesser, but measureable, extent, shorter fillet lengths resulted in thinner corner boundary layers. Overall, of the configurations tested, the largest radius resulted in the best combination of control in the corner, evidenced by a reduction in boundary-layer thickness, coupled with minimal impacts at the tunnel centerline.

Strained layer InP/InGaAs quantum well laser

NASA Technical Reports Server (NTRS)

Forouhar, Siamak (Inventor); Larsson, Anders G. (Inventor); Ksendzov, Alexander (Inventor); Lang, Robert J. (Inventor)

1993-01-01

Strained layer single or multiple quantum well lasers include an InP substrate, a pair of lattice-matched InGaAsP quarternary layers epitaxially grown on the substrate surrounding a pair of lattice matched In.sub.0.53 Ga.sub.0.47 As ternary layers surrounding one or more strained active layers of epitaxially grown, lattice-mismatched In.sub.0.75 Ga.sub.0.25 As. The level of strain is selected to control the bandgap energy to produce laser output having a wavelength in the range of 1.6 to 2.5 .mu.m. The multiple quantum well structure uses between each active layer. Diethyl zinc is used for p-type dopant in an InP cladding layer at a concentration level in the range of about 5.times.10.sup.17 /cm.sup.3 to about 2.times.10.sup.18 /cm.sup.3. Hydrogen sulfide is used for n-type dopant in the substrate.

Highly Efficient and Uniform 1 cm2 Perovskite Solar Cells with an Electrochemically Deposited NiOx Hole-Extraction Layer.

PubMed

Park, Ik Jae; Kang, Gyeongho; Park, Min Ah; Kim, Ju Seong; Seo, Se Won; Kim, Dong Hoe; Zhu, Kai; Park, Taiho; Kim, Jin Young

2017-06-22

Given that the highest certified conversion efficiency of the organic-inorganic perovskite solar cell (PSC) already exceeds 22 %, which is even higher than that of the polycrystalline silicon solar cell, the significance of new scalable processes that can be utilized for preparing large-area devices and their commercialization is rapidly increasing. From this perspective, the electrodeposition method is one of the most suitable processes for preparing large-area devices because it is an already commercialized process with proven controllability and scalability. Here, a highly uniform NiO x layer prepared by electrochemical deposition is reported as an efficient hole-extraction layer of a p-i-n-type planar PSC with a large active area of >1 cm 2 . It is demonstrated that the increased surface roughness of the NiO x layer, achieved by controlling the deposition current density, facilitates the hole extraction at the interface between perovskite and NiO x , and thus increases the fill factor and the conversion efficiency. The electrochemically deposited NiO x layer also exhibits extremely uniform thickness and morphology, leading to highly efficient and uniform large-area PSCs. As a result, the p-i-n-type planar PSC with an area of 1.084 cm 2 exhibits a stable conversion efficiency of 17.0 % (19.2 % for 0.1 cm 2 ) without showing hysteresis effects. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Efficient and Uniform 1 cm 2 Perovskite Solar Cells with an Electrochemically Deposited NiO x Hole-Extraction Layer

DOE PAGES

Park, Ik Jae; Kang, Gyeongho; Park, Min Ah; ...

2017-05-10

Here, given that the highest certified conversion efficiency of the organic-inorganic perovskite solar cell (PSC) already exceeds 22%, which is even higher than that of the polycrystalline silicon solar cell, the significance of new scalable processes that can be utilized for preparing large-area devices and their commercialization is rapidly increasing. From this perspective, the electrodeposition method is one of the most suitable processes for preparing large-area devices because it is an already commercialized process with proven controllability and scalability. Here, a highly uniform NiO x layer prepared by electrochemical deposition is reported as an efficient hole-extraction layer of a p-i-n-typemore » planar PSC with a large active area of >1 cm 2. It is demonstrated that the increased surface roughness of the NiO x layer, achieved by controlling the deposition current density, facilitates the hole extraction at the interface between perovskite and NiO x, and thus increases the fill factor and the conversion efficiency. The electrochemically deposited NiO x layer also exhibits extremely uniform thickness and morphology, leading to highly efficient and uniform large-area PSCs. As a result, the p-i-n-type planar PSC with an area of 1.084 cm 2 exhibits a stable conversion efficiency of 17.0% (19.2% for 0.1 cm 2) without showing hysteresis effects.« less

Concentration and spatial distribution of lead in soil used for ammunition destruction.

PubMed

do Nascimento Guedes, Jair; do Amaral Sobrinho, Nelson Moura Brasil; Ceddia, Marcos Bacis; Vilella, André Luis Oliveira; Tolón-Becerra, Alfredo; Lastra-Bravo, Xavier Bolívar

2012-10-01

Studies on heavy metal contamination in soils used for ammunition disposal and destruction are still emerging. The present study aimed to evaluate the contamination level and spatial distribution of lead in disposal and destruction areas. This site was used for ammunition disposal and destruction activities for 20 years. The ammunition destruction site (1,296 ha), a sampling system that followed a sampling grid (5 m × 5 m) with 30 points was adopted and samples were collected at the following five depths with a total of 150 samples. During the collection procedure, each sampling grid point was georeferenced using a topographic global positioning system. Data were validated through semivariogram and kriging models using Geostat software. The results demonstrated that the average lead value was 163 mg kg(-1), which was close to the investigation limit and the contamination levels were higher downstream than upstream. The results showed that there was lead contamination at the destruction site and that the contamination existed mainly at the surface layer depth. However, high lead concentrations were also found at deeper soil depths in the destruction area due to frequent detonations. According to the planimetry data, the areas that require intervention significantly decreased with increasing depths in the following order: 582.7 m(2) in the 0-20 cm layer; 194.6 m(2) in the 20-40 cm layer; 101.6 m(2) in the 40-60 cm layer; and 45.3 m(2) in the 60-80 cm layer.

Amorphous surface layers in Ti-implanted Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knapp, J.A.; Follstaedt, D.M.; Picraux, S.T.

1979-01-01

Implanting Ti into high-purity Fe results in an amorphous surface layer which is composed of not only Fe and Ti, but also C. Implantations were carried out at room temperature over the energy range 90 to 190 keV and fluence range 1 to 2 x 10/sup 16/ at/cm/sup 2/. The Ti-implanted Fe system has been characterized using transmission electron microscopy (TEM), ion backscattering and channeling analysis, and (d,p) nuclear reaction analysis. The amorphous layer was observed to form at the surface and grow inward with increasing Ti fluence. For an implant of 1 x 10/sup 17/ Ti/cm/sup 2/ at 180more » keV the layer thickness was 150 A, while the measured range of the implanted Ti was approx. 550 A. This difference is due to the incorporation of C into the amorphous alloy by C being deposited on the surface during implantation and subsequently diffusing into the solid. Our results indicate that C is an essential constituent of the amorphous phase for Ti concentrations less than or equal to 10 at. %. For the 1 x 10/sup 17/ Ti/cm/sup 2/ implant, the concentration of C in the amorphous phase was approx. 25 at. %, while that of Ti was only approx. 3 at. %. A higher fluence implant of 2 x 10/sup 17/ Ti/cm/sup 2/ produced an amorphous layer with a lower C concentration of approx. 10 at. % and a Ti concentration of approx. 20 at. %.« less

New Conceptual Model for Soil Treatment Units: Formation of Multiple Hydraulic Zones during Unsaturated Wastewater Infiltration.

PubMed

Geza, Mengistu; Lowe, Kathryn S; Huntzinger, Deborah N; McCray, John E

2013-07-01

Onsite wastewater treatment systems are commonly used in the United States to reclaim domestic wastewater. A distinct biomat forms at the infiltrative surface, causing resistance to flow and decreasing soil moisture below the biomat. To simulate these conditions, previous modeling studies have used a two-layer approach: a thin biomat layer (1-5 cm thick) and the native soil layer below the biomat. However, the effect of wastewater application extends below the biomat layer. We used numerical modeling supported by experimental data to justify a new conceptual model that includes an intermediate zone (IZ) below the biomat. The conceptual model was set up using Hydrus 2D and calibrated against soil moisture and water flux measurements. The estimated hydraulic conductivity value for the IZ was between biomat and the native soil. The IZ has important implications for wastewater treatment. When the IZ was not considered, a loading rate of 5 cm d resulted in an 8.5-cm ponding. With the IZ, the same loading rate resulted in a 9.5-cm ponding. Without the IZ, up to 3.1 cm d of wastewater could be applied without ponding; with the IZ, only up to 2.8 cm d could be applied without ponding. The IZ also plays a significant role in soil moisture distribution. Without the IZ, near-saturation conditions were observed only within the biomat, whereas near-saturation conditions extended below the biomat with the IZ. Accurate prediction of ponding is important to prevent surfacing of wastewater. The degree of water and air saturation influences pollutant treatment efficiency through residence time, volatility, and biochemical reactions. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Highly conductive, multi-layer composite precursor composition to fuel cell flow field plate or bipolar plate

DOEpatents

Jang, Bor Z [Centerville, OH; Zhamu, Aruna [Centerville, OH; Guo, Jiusheng [Centerville, OH

2011-02-15

This invention provides a moldable, multiple-layer composite composition, which is a precursor to an electrically conductive composite flow field plate or bipolar plate. In one preferred embodiment, the composition comprises a plurality of conductive sheets and a plurality of mixture layers of a curable resin and conductive fillers, wherein (A) each conductive sheet is attached to at least one resin-filler mixture layer; (B) at least one of the conductive sheets comprises flexible graphite; and (C) at least one resin-filler mixture layer comprises a thermosetting resin and conductive fillers with the fillers being present in a sufficient quantity to render the resulting flow field plate or bipolar plate electrically conductive with a conductivity no less than 100 S/cm and thickness-direction areal conductivity no less than 200 S/cm.sup.2.

Improving fatigue resistance of Pb(Zr,Ti)O3 thin films by using PbZrO3 buffer layers

NASA Astrophysics Data System (ADS)

Mensur Alkoy, Ebru; Uchiyama, Kiyoshi; Shiosaki, Tadashi; Alkoy, Sedat

2006-05-01

Ferroelectric Pb(Zr0.52Ti0.48)O3 (PZT) thin films with PbZrO3 (PZ) buffer layers were prepared on Pt(111)/Ti/SiO2/Si(100) substrates using a hybrid rf magnetron sputtering and sol-gel process. Texture of PZT films was found to depend on Pb content of PZ buffer layers. Buffered PZT films displayed comparable ferroelectric properties (2Pr=38-53 μC/cm2,2Ec=136-170 kV/cm) with unbuffered PZT. Asymmetric leakage current and fatigue behavior with superior fatigue resistance was observed in PZ buffered PZT compared to unbuffered films. PZ buffer layers were found to affect crystallization and texture of PZT, and act as a capacitive interface layer possibly blocking charge injection from electrodes.

Dependence of magnetic properties on different buffer layers of Mn3.5Ga thin films

NASA Astrophysics Data System (ADS)

Takahashi, Y.; Sato, K.; Shima, T.; Doi, M.

2018-05-01

D022-Mn3.5Ga thin films were prepared on MgO (100) single crystalline substrates with different buffer layer (Cr, Fe, Cr/Pt and Cr/Au) using an ultra-high-vacuum electron beam vapor deposition system. From XRD patterns, a fundamental (004) peak has clearly observed for all samples. The relatively low saturation magnetization (Ms) of 178 emu/cm3, high magnetic anisotropy (Ku) of 9.1 Merg/cm3 and low surface roughness (Ra) of 0.30 nm were obtained by D022-Mn3.5Ga film (20 nm) on Cr/Pt buffer layer at Ts = 300 °C, Ta = 400 °C (3h). These findings suggest that MnGa film on Cr/Pt buffer layer is a promising PMA layer for future spin electronics devices.

Vertical stratification of bacteria and archaea in sediments of a boreal stratified humic lake

NASA Astrophysics Data System (ADS)

Rissanen, Antti J.; Mpamah, Promise; Peura, Sari; Taipale, Sami; Biasi, Christina; Nykänen, Hannu

2015-04-01

Boreal stratified humic lakes, with steep redox gradients in the water column and in the sediment, are important sources of methane (CH4) to the atmosphere. CH4 flux from these lakes is largely controlled by the balance between CH4-production (methanogenesis), which takes place in the organic rich sediment and in the deepest water layers, and CH4-consumption (methanotrophy), which takes place mainly in the water column. While there is already some published information on the activity, diversity and community structure of bacteria in the water columns of these lakes, such information on sediment microbial communities is very scarce. This study aims to characterize the vertical variation patterns in the diversity and the structure of microbial communities in sediment of a boreal stratified lake. Particular focus is on microbes with the potential to contribute to methanogenesis (fermentative bacteria and methanogenic archaea) and to methanotrophy (methanotrophic bacteria and archaea). Two sediment cores (26 cm deep), collected from the deepest point (~6 m) of a small boreal stratified lake during winter-stratification, were divided into depth sections of 1 to 2 cm for analyses. Communities were studied from DNA extracted from sediment samples by next-generation sequencing (Ion Torrent) of polymerase chain reaction (PCR) - amplified bacterial and archaeal 16S rRNA gene amplicons. The abundance of methanogenic archaea was also specifically studied by quantitative-PCR of methyl coenzyme-M reductase gene (mcrA) amplicons. Furthermore, the community structure and the abundance of bacteria were studied by phospholipid fatty acid (PLFA) analysis. Dominant potential fermentative bacteria belonged to families Syntrophaceae, Clostridiaceae and Peptostreptococcaceae. There were considerable differences in the vertical distribution among these groups. The relative abundance of Syntrophaceae started to increase from the sediment surface, peaked at depth layer from 5 to 10 cm (up to 21 % of bacterial 16S rRNA gene amplicons) and decreased gradually towards deeper layers while the relative abundances of Clostridiaceae and Peptostreptococcaceae started to increase at deeper depths, at 5 cm and 10 cm, respectively, both peaking at depth layer from 20 to 26 cm (Clostridiaceae up to 13 % and Peptostreptococcaceae up to 11 % of bacterial 16S rRNA amplicons). Methanogenic community was dominated by acetoclastic methanogens (genus Methanosaeta), which were most abundant at depth layer from sediment surface to 10 cm (up to 87 % of archaeal 16S rRNA gene amplicons) and decreased drastically until the depth of 18 cm having quite stable relative abundance from 18 to 26 cm (5 to 11 % of archaeal 16S rRNA gene amplicons). Hydrogenotrophic methanogens (Methanoregula, Methanolinea, Methanospirillum, Methanocella) (3 to 11 % of archaeal 16S rRNA gene amplicons) did not show any specific depth patterns. The proportion of methanotrophic microbes was very low and they consisted almost completely of type II methanotrophic bacteria (family Methylocystaceae), which had highest relative abundance at depth layer from 5 to 10 cm (up to 3 % of bacterial 16S rRNA gene amplicons) and were almost absent below 15 cm. Anaerobic methanotrophic archaea were not detected. These findings will be discussed with results from PLFA and q-PCR analyses.

Carrier Concentration Control of GaSb/GaInAsSb System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lazzari, J.-L.; Anda, F. de; Nieto, J.

2007-02-22

The residual carrier concentration of GaSb and GaSb-lattice matched Ga1-xInxAsySb1-y alloys (x = 0.12-0.26; y = 0.9x) grown by liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) was studied as a function of growth temperature, V/III ratio and alloy composition. Typical carrier concentrations p {approx} 2-3x1016 cm-3 were obtained for undoped GaSb grown by MBE at 480 deg. C, by LPE from Ga-rich melt at low temperature (400 deg. C), and by LPE from Sb-rich melts at {approx}600 deg. C. The native acceptor defect responsible of the high p-type residual doping in GaSb is reduced when the indium concentrationmore » is increased, and disappears for indium rich alloys (x = 0.23, 0.26). Tellurium compensation was used for controlled n-type doping in the (0.05-30)x1017 cm-3 range. A maximum of free carrier concentration was 1.5x1018 cm-3 for LPE layers, 2x1018 cm-3 for MBE layers grown at 1.0 {mu}m/h, 3.5x1018 cm-3 for MBE layers grown at 0.2 {mu}m/h. SIMS measurements showed Te concentrations of more than 1020 at/cm3, suggesting the formation of ternary GaSb1-xTex solid solution.« less

A delta-doped amorphous silicon thin-film transistor with high mobility and stability

NASA Astrophysics Data System (ADS)

Kim, Pyunghun; Lee, Kyung Min; Lee, Eui-Wan; Jo, Younjung; Kim, Do-Hyung; Kim, Hong-jae; Yang, Key Young; Son, Hyunji; Choi, Hyun Chul

2012-12-01

Ultrathin doped layers, known as delta-doped layers, were introduced within the intrinsic amorphous silicon (a-Si) active layer to fabricate hydrogenated amorphous silicon (a-Si:H) thin-film transistors (TFTs) with enhanced field-effect mobility. The performance of the delta-doped a-Si:H TFTs depended on the phosphine (PH3) flow rate and the distance from the n+ a-Si to the deltadoping layer. The delta-doped a-Si:H TFTs fabricated using a commercial manufacturing process exhibited an enhanced field-effect mobility of approximately ˜0.23 cm2/Vs (compared to a conventional a-Si:H TFT with 0.15 cm2/Vs) and a desirable stability under a bias-temperature stress test.

Enhanced amplified spontaneous emission using layer-by-layer assembled cowpea mosaic virus

NASA Astrophysics Data System (ADS)

Li, Na; Deng, Zhaoqi; Lin, Yuan; Zhang, Xiaojie; Geng, Yanhou; Ma, Dongge; Su, Zhaohui

2009-01-01

Layer-by-layer assembly technique was used to construct ultrathin film of cowpea mosaic virus (CPMV) by electrostatic interactions, and the film was employed as a precursor on which an OF8T2 film was deposited by spin coating. Amplified spontaneous emission (ASE) was observed and improved for the OF8T2 film. Compared with OF8T2 film on quartz, the introduction of CPMV nanoparticles reduced the threshold and loss, and remarkably increased the net gain. The threshold, loss, and gain reached 0.05 mJ/pulse, 6.9 cm-1, and 82 cm-1, respectively. CPMV nanoparticles may enormously scatter light, resulting in a positive feedback, thus the ASE is easily obtained and improved.

Optical measurements of absorption changes in two-layered diffusive media

NASA Astrophysics Data System (ADS)

Fabbri, Francesco; Sassaroli, Angelo; Henry, Michael E.; Fantini, Sergio

2004-04-01

We have used Monte Carlo simulations for a two-layered diffusive medium to investigate the effect of a superficial layer on the measurement of absorption variations from optical diffuse reflectance data processed by using: (a) a multidistance, frequency-domain method based on diffusion theory for a semi-infinite homogeneous medium; (b) a differential-pathlength-factor method based on a modified Lambert-Beer law for a homogeneous medium and (c) a two-distance, partial-pathlength method based on a modified Lambert-Beer law for a two-layered medium. Methods (a) and (b) lead to a single value for the absorption variation, whereas method (c) yields absorption variations for each layer. In the simulations, the optical coefficients of the medium were representative of those of biological tissue in the near-infrared. The thickness of the first layer was in the range 0.3-1.4 cm, and the source-detector distances were in the range 1-5 cm, which is typical of near-infrared diffuse reflectance measurements in tissue. The simulations have shown that (1) method (a) is mostly sensitive to absorption changes in the underlying layer, provided that the thickness of the superficial layer is ~0.6 cm or less; (2) method (b) is significantly affected by absorption changes in the superficial layer and (3) method (c) yields the absorption changes for both layers with a relatively good accuracy of ~4% for the superficial layer and ~10% for the underlying layer (provided that the absorption changes are less than 20-30% of the baseline value). We have applied all three methods of data analysis to near-infrared data collected on the forehead of a human subject during electroconvulsive therapy. Our results suggest that the multidistance method (a) and the two-distance partial-pathlength method (c) may better decouple the contributions to the optical signals that originate in deeper tissue (brain) from those that originate in more superficial tissue layers.

Application Of Two Dimensional Electrical Resistivity Tomography Method For Delineating Cavities And Flowpath In Sinkhole Prone Area Of Armala Valley, Pokhara, Western Nepal

NASA Astrophysics Data System (ADS)

Bhusal, U. C.; Dwivedi, S.; Ghimire, H.; Ulak, P. D.; Khatiwada, B.; Rijal, M. L.; Neupane, Y.; Aryal, S.; Pandey, D.; Gautam, A.; Mishra, S.

2017-12-01

Sudden release of turbid groundwater through piping in the Kali Khola and subsequent formation of over one hundred twenty sinkholes since 18 November, 2013 to May, 2014 in Armala Valley in northern part of Pokhara created havoc to the local residents. The main objective of the work is to investigate subsurface anomalies so as to locate the subsurface cavities, groundwater movement and areas prone to sinkholes formation in the area. Findings of the several studies and observations carried out in area by the authors and preventive measures carried out by Department of Water Induced Disaster Management are presented in the paper. To fulfill the objective 2D-Electrical Resistivity Tomography Survey was carried out at sixty five profiles with minimum electrode spacing from 1 m to 5 m on different profiles using WDJD-4 Resistivity meter. Res2Dinv Software was used for processing and interpretation of the acquired data. Geological mapping, preparation of columnar section of the sinkholes and river bank were conducted. Hand auguring, tracer test and topography survey were also carried out in the area. Different geophysical anomalies were identified in 2D-ERT survey which indicates the presence of compositional difference in layered sediments, undulations in depositional pattern with top humus layer of thickness 0.5 m, loose unconsolidated gravel layer 0.5 m - 4 m and clayey silt/silty clay layer upto 75 m depth. The cavities were found both in clayey silt layer and gravel layer with size ranging from 1-2 m to 10-12 m in depth and 2 m-10 m in diameter either empty or water filled depending on locations. Fifteen cavities that were detected during survey were excavated and immediately filled up. Three major and four minor groundwater flow paths were detected which has been later confirmed by tracer test, formation of new sinkholes along the path and during excavation for construction of underground structures for blocking the underground flow. Major flow path was detected at a depth of 7 m. Undulations in the interface between gravel layer and underlying clayey silt layer, infiltration of acidic fluid, formation of fissures, cracks and dissolution, piping in the clayey silt layer increased the size of cavity, encroachment of Duhani Khola channel, rapid deepening of the Kali Khola are major causes for formation of sinkholes in Armala Valley.

Comparative study of ITO and TiN fabricated by low-temperature RF biased sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simon, Daniel K., E-mail: daniel.simon@namlab.com; Schenk, Tony; Dirnstorfer, Ingo

2016-03-15

Radio frequency (RF) biasing induced by a second plasma source at the substrate is applied to low-temperature sputtering processes for indium tin oxide (ITO) and titanium nitride (TiN) thin films. Investigations on crystal structure and surface morphology show that RF-biased substrate plasma processes result in a changed growth regime with different grain sizes and orientations than those produced by processes without a substrate bias. The influence of the RF bias is shown comparatively for reactive RF-sputtered ITO and reactive direct-current-sputtered TiN. The ITO layers exhibit an improved electrical resistivity of 0.5 mΩ cm and an optical absorption coefficient of 0.5 × 10{sup 4 }cm{supmore » −1} without substrate heating. Room-temperature sputtered TiN layers are deposited that possess a resistivity (0.1 mΩ cm) of 3 orders of magnitude lower than, and a density (5.4 g/cm{sup 3}) up to 45% greater than, those obtained from layers grown using the standard process without a substrate plasma.« less

Helium-induced hardening effect in polycrystalline tungsten

NASA Astrophysics Data System (ADS)

Kong, Fanhang; Qu, Miao; Yan, Sha; Zhang, Ailin; Peng, Shixiang; Xue, Jianming; Wang, Yugang

2017-09-01

In this paper, helium induced hardening effect of tungsten was investigated. 50 keV He2+ ions at fluences vary from 5 × 1015 cm-2 to 5 × 1017 cm-2 were implanted into polycrystalline tungsten at RT to create helium bubble-rich layers near the surface. The microstructure and mechanical properties of the irradiated specimens were studied by TEM and nano-indentor. Helium bubble rich layers are formed in near surface region, and the layers become thicker with the rise of fluences. Helium bubbles in the area of helium concentration peak are found to grow up, while the bubble density is almost unchanged. Obvious hardening effect is induced by helium implantation in tungsten. Micro hardness increases rapidly with the fluence firstly, and more slowly when the fluence is above 5 × 1016 cm-2. The hardening effect of tungsten can be attributed to helium bubbles, which is found to be in agreement with the Bacon-Orowan stress formula. The growing diameter is the major factor rather than helium bubbles density (voids distance) in the process of helium implantation at fluences below 5 × 1017 cm-2.

Ion irradiation-induced easy-cone anisotropy in double-MgO free layers for perpendicular magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Teixeira, B. M. S.; Timopheev, A. A.; Caçoilo, N. F. F.; Auffret, S.; Sousa, R. C.; Dieny, B.; Alves, E.; Sobolev, N. A.

2018-05-01

We have used the ferromagnetic resonance in the X-band (9.37 GHz) to investigate the effect of 400 keV Ar+ irradiation on the perpendicular magnetic anisotropy (PMA) and Gilbert damping parameter, α, of double-MgO free layers designed for application in perpendicular magnetic tunnel junctions. The samples comprised a MgO/Fe72Co8B20/X(0.2 nm)/Fe72Co8B20/MgO layer stack, where X stands for an ultrathin Ta or W spacer. Samples with two different total FeCoB layer thicknesses, tFCB = 3.0 nm and tFCB = 2.6 nm, were irradiated with ion fluences ranging from 1012 cm-2 to 1016 cm-2. The effective first-order PMA field, BK1, decreased nearly linearly with the logarithm of the fluence for both FeCoB thicknesses and spacer elements. The decrease in BK1, which is likely caused by an ion-induced intermixing at the FeCoB/MgO interfaces, resulted in a reorientation of the magnetization of the free layers with tFCB = 2.6 nm, initially exhibiting a perpendicular easy-axis anisotropy. For intermediate fluences, 1013 cm-2 and 1014 cm-2, easy-cone states with different cone angles could be induced in the free layer with a W spacer. Importantly, no corresponding increase in the Gilbert damping was observed. This study shows that ion irradiation can be used to tune the easy-cone anisotropy in perpendicular magnetic tunnel junctions, which is interesting for spintronic applications such as spin-torque magnetic memory devices, oscillators, and sensors.

Increase of rotation angle of soil layers during plow operation

NASA Astrophysics Data System (ADS)

Vasilenko, VV; Afonichev, D. N.; Vasilenko, S. V.; Khakhulin, A. N.

2018-03-01

One of the advantages of plowing is the ability of the plow to hide the weed seeds deep into the soil. The depth of the embankment exceeds 10-12 cm, from there the weeds can not rise to the surface of the soil. They perish halfway. But for this, it is necessary to wrap the soil layers at an angle close to 180 °. Modern ploughs can not turn the layers of soil at an angle of more than 135 °, therefore the plow is required to be equipped with additional working elements. The aim of the study is to create an adaptation to the plow to expand the furrow before laying the next soil layer. In a wide furrow, the formation will completely tip, the previous layer will not interfere with it. The device is a set of vertical shields. Each shield is fixed behind the working body of the plow. It is installed with an angle of attack of 20-25 ° to move the previous layer to expand the furrow by 10-12 cm. The model and industrial samples of the plow have shown improved agrotechnical indicators. The average angle of the formation rotation was 177 °, the burial of plant residues in the soil increased from 61 to 99%. The field surface with blocks more than 5 cm decreased from 36.3 to 13.4%, the height of the ridges decreased from 7 to 4 cm. The force of soil pressure on the shield was measured by a strain gage. It is 130-330 N depending on the depth of processing and the speed of movement. The increase in power costs for the four-hull plow was 190-750 W. The coulters on the plow are unnecessary, and this saves energy more than its increase for shields.

Aerosol and ozone distributions over the western North Atlantic during WATOX-86

NASA Astrophysics Data System (ADS)

Bridgman, H. A.; Schnell, Russell C.; Bodhaine, B. A.; Oltmans, S. J.

1988-03-01

On January 4, 6, 8, and 9, 1986, a series of National Oceanic and Atmospheric Administration WP-3D research flights was conducted over the western Atlantic Ocean 200-300 km off the coast of North America from Nova Scotia to Georgia as part of the Western Atlantic Ocean Experiment (WATOX). Rights were made perpendicular to NW airflow to establish the flux of gas and aerosol emissions off the North American continent to the ocean. Representative condensation nucleus (CN) concentrations averaged 150-250 cm-3 in the free troposphere in clean conditions, but in atmospheric layers containing anthropogenic air pollution transported from long distances, CN concentrations reached 6500 cm-3. In the marine boundary layer, CN concentrations averaged 500 to 750 cm-3 under relatively clean conditions, and 1500 to 3000 cm-3 in polluted air. Aerosol scattering extinction (bsp) ranged from 70 × 10-6 m-1 in the marine boundary layer to 20 × 10-6 m-1 in the free troposphere. Aerosol bsp was not as responsive to changes in atmospheric structure as CN although factor-of-2 changes across the marine boundary layer were observed. Aerosol size spectra in the marine boundary layer were an order of magnitude greater than those in the free troposphere. Consistent peaks in the volume spectra between 8 and 10 μm diameter established the importance of sea salt as a major aerosol component. Ozone profiles in the free troposphere, normally in the 30-40 ppb range, exhibited laminae of enhanced concentrations (up to 70 ppb) at moisture boundaries, suggesting that active ozone production was occurring at these levels. Ozone concentrations within the marine boundary layer were generally lower than in the free troposphere.

From which soil metal fractions Fe, Mn, Zn and Cu are taken up by olive trees (Olea europaea L., cv. 'Chondrolia Chalkidikis') in organic groves?

PubMed

Chatzistathis, T; Papaioannou, A; Gasparatos, D; Molassiotis, A

2017-12-01

Organic farming has been proposed as an alternative agricultural system to help solve environmental problems, like the sustainable management of soil micronutrients, without inputs of chemical fertilizers. The purposes of this study were: i) to assess Fe, Mn, Zn and Cu bioavailability through the determination of sequentially extracted chemical forms (fractions) and their correlation with foliar micronutrient concentrations in mature organic olive (cv. 'Chondrolia Chalkidikis') groves; ii) to determine the soil depth and the available forms (fractions) by which the 4 metals are taken up by olive trees. DTPA extractable (from the soil layers 0-20, 20-40 and 40-60 cm) and foliar micronutrient concentrations were determined in two organic olive groves. Using the Tessier fractionation, five fractions, for all the metals, were found: exchangeable, bound to carbonates (acid-soluble), bound to Fe-Mn oxides (reducible), organic (oxidizable), as well as residual form. Our results indicated that Fe was taken up by the olive trees as organic complex, mainly from the soil layer 40-60 cm. Manganese was taken up from the exchangeable fraction (0-20 cm); Zinc was taken up as organic complex from the layers 0-20 and 40-60 cm, as well as in the exchangeable form from the upper 20 cm. Copper was taken up from the soil layers 0-20 and 40-60 cm as soluble organic complex, and as exchangeable ion from the upper 20 cm. Our data reveal the crucial role of organic matter to sustain metal (Fe, Zn and Cu) uptake -as soluble complexes-by olive trees, in mature organic groves grown on calcareous soils; it is also expected that these data will constitute a thorough insight and useful tool towards a successful nutrient and organic C management for organic olive groves, since no serious nutritional deficiencies were found. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of hydrogen on the device performance and stability characteristics of amorphous InGaZnO thin-film transistors with a SiO2/SiNx/SiO2 buffer

NASA Astrophysics Data System (ADS)

Han, Ki-Lim; Ok, Kyung-Chul; Cho, Hyeon-Su; Oh, Saeroonter; Park, Jin-Seong

2017-08-01

We investigate the influence of the multi-layered buffer consisting of SiO2/SiNx/SiO2 on amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The multi-layered buffer inhibits permeation of water from flexible plastic substrates and prevents degradation of overlying organic layers. The a-IGZO TFTs with a multi-layered buffer suffer less positive bias temperature stress instability compared to the device with a single SiO2 buffer layer after annealing at 250 °C. Hydrogen from the SiNx layer diffuses into the active layer and reduces electron trapping at loosely bound oxygen defects near the SiO2/a-IGZO interface. Quantitative analysis shows that a hydrogen density of 1.85 × 1021 cm-3 is beneficial to reliability. However, the multi-layered buffer device annealed at 350 °C resulted in conductive characteristics due to the excess carrier concentration from the higher hydrogen density of 2.12 × 1021 cm-3.

Application of Micro-ramp Flow Control Devices to an Oblique Shock Interaction

NASA Technical Reports Server (NTRS)

Hirt, Stefanie; Anderson, Bernhard

2007-01-01

Tests are planned in the 15cm x 15cm supersonic wind tunnel at NASA Glenn to demonstrate the applicability of micro-ramp flow control to the management of shock wave boundary layer interactions. These tests will be used as a database for computational fluid dynamics (CFD) validation and Design of Experiments (DoE) design information. Micro-ramps show potential for mechanically simple and fail-safe boundary layer control.

Application of atomic layer deposited microchannel plates to imaging photodetectors with high time resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegmund, O. H. W.; McPhate, J. B.; Tremsin, A. S.

Novel microchannel plates have been constructed using borosilicate glass micro-capillary array substrates with 20 mu m and 10 mu m pores and coated with resistive, and secondary electron emissive, layers by atomic layer deposition. Microchannel plates in 33 mm, 50 mm and 20 cm square formats have been made and tested. Although their amplification, imaging, and timing properties are comparable to standard glass microchannel plates, the background rates and lifetime characteristics are considerably improved. Sealed tube detectors based on the Planacon tube, and a 25 mm cross delay line readout tube with a GaN(Mg) opaque photocathode deposited on borosilicate microchannelmore » plates have been fabricated. Considerable progress has also been made with 20 cm microchannel plates for a 20 cm format sealed tube sensor with strip-line readout that is being developed for Cherenkov light detection.« less

The September 16, 2015 Illapel Tsunami - Sedimentology of tsunami deposits at the beaches of La Serena and Coquimbo

NASA Astrophysics Data System (ADS)

Bahlburg, Heinrich; Nentwig, Vanessa; Matthias, Kreutzer

2016-04-01

On September 16, 2015, at 7:54 pm local time, an earthquake with Mw 8.3 occurred off the coast of Central Chile, 46 km west of the town of Illapel. Its hypocenter was located at a depth of 8.7 km in the transition zone from the Chilean flat slab to the central Chilean steep slab subduction geometry, and near the intersection of the Juan Fernandez Ridge with the South America plate. The quake caused a predominantly minor tsunami between Caldera (c. 27°S) and Los Vilos (c. 32°S). Only at Coquimbo and La Serena (c. 30°S) did the tsunami attain large wave heights on the order of 4.5 m leading to flooding and destruction of infrastructure. Maximum inundation distance was c. 700 m at Playa Changa, Coquimbo Bay. Minor flooding occurred along the northward adjacent beaches of La Serena reaching inundation distances of up to 150 m. Tsunami deposits are usually the only observable evidence of past events. To understand how tsunami deposits form and are preserved, and how they can be identified in the geological record, it is of paramount importance to undertake detailed studies in the wake of actual events. Here we report initial field data of a sedimentological post-tsunami field survey undertaken in October 2015. The most comprehensive and instructive sedimentological record of the September 16, 2015 tsunami is preserved at Playa Los Fuertes in La Serena. Along a 30 m long trench perpendicular to the coast we observed a laminated package of tsunami deposits of varying thickness. The deposits have an erosive basal unconformity with an amplitude of at least 10 cm. The preserved deposit thickness varies between 10 an 50 cm. The deposit consists of 7 layers of variable thickness, ranging between dark laminae a few millimeters thick and rich in heavy minerals, and lighter colored sand layers up to 15 cm thick. Grain size distributions are moderately well to well sorted and unimodal with modes between 1.3 and 2.0 Φ (medium sand). A c. 10 cm thick laminated layer in the central part of the vertical section includes mildly trough-shaped crossbeds indicating landward flow, a c. 5 cm thick layer 10 cm below the top in the interior part of the trench contains planar cross beds formed by outflow currents. Water escape occur as small sand diapirs and volcanoes within the final deposit. Water escape through small volcanoes appears to have been coeval to formation of the overlying layer by traction deposition as sand issuing from the lower layer has been preserved as a thin plume deformed in the downcurrent, i.e. landward, direction in the newly forming upper layer. Other sectors of the sediment show sand diapirs intruding up to 15 cm into the overlying tsunami deposit. The assemblage of laminae, layers and sedimentary structures indicates that the deposit records at least two events of tsunami inflow indicated by crossbeds and deformed sand volcano plumes, and one outflow event. Intervening layers without directional structures can not be assigned unequivocally to either inflow or outflow deposition.

Tantalum oxide/silicon nitride: A negatively charged surface passivation stack for silicon solar cells

NASA Astrophysics Data System (ADS)

Wan, Yimao; Bullock, James; Cuevas, Andres

2015-05-01

This letter reports effective passivation of crystalline silicon (c-Si) surfaces by thermal atomic layer deposited tantalum oxide (Ta2O5) underneath plasma enhanced chemical vapour deposited silicon nitride (SiNx). Cross-sectional transmission electron microscopy imaging shows an approximately 2 nm thick interfacial layer between Ta2O5 and c-Si. Surface recombination velocities as low as 5.0 cm/s and 3.2 cm/s are attained on p-type 0.8 Ω.cm and n-type 1.0 Ω.cm c-Si wafers, respectively. Recombination current densities of 25 fA/cm2 and 68 fA/cm2 are measured on 150 Ω/sq boron-diffused p+ and 120 Ω/sq phosphorus-diffused n+ c-Si, respectively. Capacitance-voltage measurements reveal a negative fixed insulator charge density of -1.8 × 1012 cm-2 for the Ta2O5 film and -1.0 × 1012 cm-2 for the Ta2O5/SiNx stack. The Ta2O5/SiNx stack is demonstrated to be an excellent candidate for surface passivation of high efficiency silicon solar cells.

Characteristic of pollution with groundwater inflow (90)Sr natural waters and terrestrial ecosystems near a radioactive waste storage.

PubMed

Lavrentyeva, G V

2014-09-01

The studies were conducted in the territory contaminated by (90)Sr with groundwater inflow as a result of leakage from the near-surface trench-type radioactive waste storage. The vertical soil (90)Sr distribution up to the depth of 2-3 m is analyzed. The area of radioactive contamination to be calculated with a value which exceeds the minimum significant activity 1 kBq/kg for the tested soil layers: the contaminated area for the 0-5 cm soil layer amounted to 1800 ± 85 m(2), for the 5-10 cm soil layer amounted to 300 ± 12 m(2), for the 10-15 cm soil layer amounted to 180 ± 10 m(2). It is found that (90)Sr accumulation proceeds in a natural sorption geochemical barrier of the marshy terrace near flood plain. The exposure doses for terrestrial mollusks Bradybaena fruticum are presented. The excess (90)Sr interference level was registered both in the ground and surface water during winter and summer low-water periods and autumn heavy rains. Copyright © 2014 Elsevier Ltd. All rights reserved.

A modified Bitter-type electromagnet and control system for cold atom experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luan, Tian; Zhou, Tianwei; Chen, Xuzong, E-mail: xuzongchen@pku.edu.cn

2014-02-15

We present a modified Bitter-type electromagnet which features high magnetic field, fine electronic properties and efficient heat removal. The electromagnet is constructed from a stack of copper layers separated by mica layers that have the same shape. A distinctive design of cooling channels on the insulating layers and the parallel ducts between the layers ensures low resistance for cooling water to flow. A continuous current control system is also made to regulate the current through the electromagnet. In our experiment, versatile electromagnets are applied to generate magnetic field and gradient field. From our measurements, a peak magnetic field of 1000more » G and a peak gradient field of 80 G/cm are generated in the center of the apparatuses which are 7 cm and 5 cm away from the edge of each electromagnet with a current of 230 A and 120 A, respectively. With the effective feedback design in the current control system and cooling water flow of 3.8 l/min, the stability of the current through the electromagnets can reach 10{sup −5}.« less

Intensification of freeze-thaw cycles in the soil on post-fire alpine slopes of Mount Shirouma-dake, northern Japanese Alps central Japan

NASA Astrophysics Data System (ADS)

Sasaki, A.; Suzuki, K.

2016-12-01

This is the continuous study to clarify the geo-environmental changes on the post-fire alpine slopes of Mount Shirouma-dake in the Northern Japanese Alps. The fire occurred at May 9, 2009 on the alpine slopes of Mount Shirouma-dake, and the fire spread to the Pinus pumila communities and grasslands. Although the grass had a little damage by the fire, the P. pumila received nearly impact of the fire. In the P. pumila communities where the leaf burnt, forest floor is exposed and become easy to be affected by atmospheric condition such as rain, wind, snow, and etc. First, we observed condition of the micro-landforms on post-fire slopes repeatedly for seventh years after the fire. As the results of the observation, it is clear that remarkable changes of these micro-landforms have not occurred but some litters on the forest-floor in the fired P. pumila communities are flushed out to surroundings. The litter layer on the forest-floor in the fired P. pumila communities were 3-4 cm thick in August of 2011, but it became 0.5 cm thick in September of 2014. The P. pumila communities established on the slopes consists of angular and sub-angular gravel with openwork texture, which are covered by thin soil layer. On July of 2016, the litter layer almost entirely flushed out and surface of soil layer is exposed to atmosphere. In addition, we observe the ground temperature and soil moisture, under the fired P. pumila communities and the no fired P. pumila communities since October 2009, to find influence of the fire. The ground temperature sensors were installed into at 1 cm, 10 cm, and 40 cm depth. The soil moisture sensors were installed into at 1 cm and 10 cm depth. The 1 cm depth of the soil on the post-fire slopes, several times of diurnal freeze-thaw cycles occurred on October and November since 2011, but it had not occurred in 2009 and 2010. In particular, more than 20 times of diurnal freeze-thaw cycles occurred on freezing period of 2014. The diurnal freeze-thaw cycles continue to be increasing until thawing period of 2016. The period of seasonal frost at 10 cm and 40 cm depth on the post-fire slopes are extended for two weeks. Snowmelt water is especially thought to be act on re-freezing of post-fire slopes on thawing period. These thermal condition changes are triggered by decrease in the thickness of the litter layer on the fired P. pumila communities.

Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation.

PubMed

Sudhagar, P; Asokan, K; Jung, June Hyuk; Lee, Yong-Gun; Park, Suil; Kang, Yong Soo

2011-12-01

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm(-2)) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm(-2)). When SHI irradiation of oxygen ions of fluence 1 × 10(13) ions/cm(2) was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs.

Efficient Performance of Electrostatic Spray-Deposited TiO2 Blocking Layers in Dye-Sensitized Solar Cells after Swift Heavy Ion Beam Irradiation

PubMed Central

2011-01-01

A compact TiO2 layer (~1.1 μm) prepared by electrostatic spray deposition (ESD) and swift heavy ion beam (SHI) irradiation using oxygen ions onto a fluorinated tin oxide (FTO) conducting substrate showed enhancement of photovoltaic performance in dye-sensitized solar cells (DSSCs). The short circuit current density (Jsc = 12.2 mA cm-2) of DSSCs was found to increase significantly when an ESD technique was applied for fabrication of the TiO2 blocking layer, compared to a conventional spin-coated layer (Jsc = 8.9 mA cm-2). When SHI irradiation of oxygen ions of fluence 1 × 1013 ions/cm2 was carried out on the ESD TiO2, it was found that the energy conversion efficiency improved mainly due to the increase in open circuit voltage of DSSCs. This increased energy conversion efficiency seems to be associated with improved electronic energy transfer by increasing the densification of the blocking layer and improving the adhesion between the blocking layer and the FTO substrate. The adhesion results from instantaneous local melting of the TiO2 particles. An increase in the electron transport from the blocking layer may also retard the electron recombination process due to the oxidized species present in the electrolyte. These findings from novel treatments using ESD and SHI irradiation techniques may provide a new tool to improve the photovoltaic performance of DSSCs. PMID:27502653

HST STIS Observations of the Mixing Layer in the Cat’s Eye Nebula

NASA Astrophysics Data System (ADS)

Fang, Xuan; Guerrero, Martín A.; Toalá, Jesús A.; Chu, You-Hua; Gruendl, Robert A.

2016-05-01

Planetary nebulae (PNe) are expected to have a ˜105 K interface layer between the ≥slant 106 K inner hot bubble and the ˜104 K optical nebular shell. The PN structure and evolution, and the X-ray emission, depend critically on the efficiency of the mixing of material at this interface layer. However, neither its location nor its spatial extent have ever been determined. Using high-spatial resolution HST STIS spectroscopic observations of the N v λ λ 1239,1243 lines in the Cat’s Eye Nebula (NGC 6543), we have detected this interface layer and determined its location, extent, and physical properties for the first time in a PN. We confirm that this interface layer, as revealed by the spatial distribution of the N v λ1239 line emission, is located between the hot bubble and the optical nebular shell. We estimate a thickness of 1.5× {10}16 cm and an electron density of ˜200 cm-3 for the mixing layer. With a thermal pressure of ˜2 × 10-8 dyn cm-2, the mixing layer is in pressure equilibrium with the hot bubble and ionized nebular rim of NGC 6543. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. The observations are associated with program #12509.

Effect of simulated rainfall on leaching and efficacy of fenamiphos.

PubMed

Johnson, A W; Wauchope, R D; Burgoa, B

1995-12-01

There is increasing concern in the United States about the pesticide movement in soil, groundwater contamination, and pesticide residue in food. The objective of this study was to determine the efficacy, degradation, and movement of fenamiphos (Nemacur 15G) in the soil and residues in squash fruit as influenced by four simulated rainfall treatments (2.5 or 5.0 cm each applied 1 or 3 days after nematicide application) under field conditions. In 1990, concentrations of fenamiphos were greater in the top 15 cm of soil in plots with no rainfall than in those treated with rainfall. Eighty to 95 % of the fenamiphos recovered from treated plots was found in the 0-15-cm soil layer. The concentration of fenamiphos recovered from the 0-15-cm soil layer in 1991 was approximately one-half the concentration recovered in 1990, but greater concentrations of fenamiphos sulfoxide (an oxidation product of fenamiphos) were recovered in 1991 than in 1990. Concentrations of fenamiphos, fenamiphos sulfoxide, and fenamiphos sulfone were near or below detectable levels (0.002 mg/kg soil) below the 0-15-cm soil layer. Rainfall treatments did not affect the efficacy of the nematicide against Meloidogyne incognita race 1. The concentration of fenamiphos in squash fruit in 1991 was below the detectable level (0.01 mg/kg).

Urbanization in China drives soil acidification of Pinus massoniana forests.

PubMed

Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

2015-09-24

Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10 cm (for ammonium N(NH4+(-N)), P < 0.05; for nitrate N(NO3-(-N)), P < 0.01) and 10-20 cm (for NO3-(-N), P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0-10 cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment.

Enhanced electrical properties in bilayered ferroelectric thin films

NASA Astrophysics Data System (ADS)

Zhang, Hao; Long, WeiJie; Chen, YaQing; Guo, DongJie

2013-03-01

Sr2Bi4Ti5O18 (SBTi) single layered and Sr2Bi4Ti5O18/Pb(Zr0.53Ti0.47)O3 (SBTi/PZT) bilayered thin films have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed-laser deposition (PLD). The related structural characterizations and electrical properties have been comparatively investigated. X-ray diffraction reveals that both films have crystallized into perovskite phases and scanning electron microscopy shows the sharp interfaces. Both films show well-saturated ferroelectric hysteresis loops, however, compared with the single layered SBTi films, the SBTi/PZT bilayered films have significantly increased remnant polarization ( P r) and decreased coercive field ( E c), with the applied field of 260 kV/cm. The measured P r and E c of SBTi and SBTi/PZT films were 7.9 μC/cm2, 88.1 kV/cm and 13.0 μC/cm2, 51.2 kV/cm, respectively. In addition, both films showed good fatigue-free characteristics, the switchable polarization decreased by 9% and 11% of the initial values after 2.2×109 switching cycles for the SBTi single layered films and the SBTi/PZT bilayered films, respectively. Our results may provide some guidelines for further optimization of multilayered ferroelectric thin films.

Resistivity control of unintentionally doped GaN films

NASA Astrophysics Data System (ADS)

Grzegorczyk, A. P.; Macht, L.; Hageman, P. R.; Rudzinski, M.; Larsen, P. K.

2005-05-01

GaN epilayers were grown on sapphire substrates via low temperature GaN and AlN nucleation layers (NL) by metalorganic chemical vapor phase epitaxy (MOCVD). The morphology of the individual NLs strongly depends on the carrier gas used during the growth and recrystallization and this is the key factor for control of the resistivity of the GaN layer grown on it. The GaN nucleation layer grown in presence of N2 has a higher density of islands with a statistically smaller diameter than the samples grown in H2 atmosphere. The NL grown in N2 enables the growth GaN with a sheet resistivity higher than 3×104 cm as opposed to a 0.5 cm value obtained for the NL grown in H2. Introduction of an additional intermediate (IL) low temperature (GaN or AlN) nucleation layer changes the GaN epilayer resistivity to about 50 cm, regardless of the carrier gas used during the growth of the IL. Defect selective etching demonstrated that control of the type and density of the dislocations in GaN enables the growth of highly resistive layers without any intentional acceptor doping (Mg, Zn). It will be demonstrated that by changing the ratio of edge type to screw dislocations the resistivity of the layer can be changed by a few orders of magnitude.

Integration of (208) oriented epitaxial Hf-doped Bi4Ti3O12 with (0002) GaN using SrTiO3/TiO2 buffer layer

NASA Astrophysics Data System (ADS)

Luo, W. B.; Zhu, J.; Li, Y. R.; Wang, X. P.; Zhang, Y.

2009-05-01

Hf-doped Bi4Ti3O12 (BTH) ferroelectric films with excellent electrical properties were epitaxially integrated with GaN semiconductor using (111) SrTiO3 (STO)/rutile (200) TiO2 as buffer layer. The STO/TiO2 buffer layer was deposited by laser molecular beam epitaxy. The structural characteristics of the buffer layer were in situ and ex situ characterized by reflective high energy electron diffraction, x-ray diffraction (XRD), and high resolution transmission microscopy. The overlaying SrRuO3 (SRO) and BTH films were then deposited by pulsed laser deposition. XRD spectra, including θ-2θ and Φ scans, show that the (208) BTH films were epitaxially grown on GaN, and the BTH films inherit the in-plane twin-domain of STO buffer layer. Electrical measurements demonstrate that the non-c axis BTH films possess a large remnant polarization (2Pr=45 μC/cm2), excellent fatigue endurance (10.2% degradation after 1.1×1010 switching cycles), and a low leakage current density (1.94×10-7 A/cm2 at an electric field of 200 kV/cm). These results reveal that the (208) BTH films with favorable electrical performance could be epitaxially grown on GaN template using STO/TiO2 buffer layer.

137Cs Results and Interpretation of Cesium Soil Data on the Upper Fortymile Wash Alluvial Fan, Amargosa Valley, Nevada.

NASA Astrophysics Data System (ADS)

Harrington, C.

2004-12-01

Studies using 137Cs were used to produce soil Cs profiles and to use them to determine erosion rates on interchannel divides of the Fortymile Wash alluvial fan over the last 50 years. Sample locations whose 137Cs profiles most resemble the reference-sample (stable surface) profiles are located on interchannel divide areas between distributary channels. These profiles are similar to the reference profiles that have low 137Cs values (in the range of 0.02 to 0.08 pCi/g) in the 3 to 6 cm layers. However, the surface layers (1-3 cm depth) typically have values much less than the reference samples from equivalent depths (range from 0.251 to 0.421 pCi/g). The data indicate that many of these interchannel divide areas have had part of the upper layer removed. Interchannel divide areas have the least likelihood of having been submerged during floods over the last fifty years. Thus, the loss of material from these otherwise stable surfaces appears to be due to eolian processes. Erosion of an interchannel divide area with little evidence of recent water movement is most easily explained by eolian removal. Evidence for wind erosion as the predominant process on the interchannel divide areas includes the lack of new or developing stream channels and the presence of modern coppice dunes near channels on interchannel divides. The presence of nearby Big Dune and other eolian deposits provides strong support for eolian erosion and transport. The amount of material removed from the interchannel divide areas was estimated by comparing the 137Cs value of the upper 3 cm layer to that of the reference value and calculating the thickness of the layer that would have to be removed to obtain the lower value. Applying this method across the interchannel divide sample locations indicates 1 to 2 cm of material has been removed from the interchannel divide surfaces in the last 50 years. This results in erosion rates that range from 0.02 to 0.04 cm/yr. These rates are similar to erosion rates of: (a) 0.019 cm/yr predicted to occur on farmland in Amargosa Valley (obtained from BSC 2004 [DIRS 169459], Section 6.4.2 by converting 0.19 kg/m2-yr using ash bulk density of 1 g/cm3; (b) 0.02 cm/yr estimated by the U.S. Department of Agriculture to have occurred on non-cultivated cropland and pastureland in Nevada (obtained from USDA 2000 [160548], Table 11 and calculated using 1 ton/acre-yr x 907 kg/ton x 2.47 x 10-4 acre/m x 0.001 m3/kg [bulk density] x 100 cm/m = 0.02 cm/yr). Overbank deposits on the interchannel divide areas indicative of periodic flooding are uncommon and restricted to narrow strips along the channel banks. The overbank and channel deposit samples have similar 137Cs signatures (the 3 to 6 cm layers and the 6 to 9 cm layers have nearly the same values in the 0.100-0.200 pCi/g range), indicating that the material from each environ was mixed during transport and deposited as a homogeneous sediment. The absence of many overbank deposits along the channel margins today indicates that flows sufficient to form extensive overbank flooding down Fortymile Wash and its distributary channels have not occurred in more than 50 years. Therefore, the channels currently transport most of their sediment load across the fan until it reaches the toe of the fan, where deposition occurs on the broad flats to the south or into the channel of the Amargosa River.

Wearable Fabrics with Self-Branched Bimetallic Layered Double Hydroxide Coaxial Nanostructures for Hybrid Supercapacitors.

PubMed

Nagaraju, Goli; Chandra Sekhar, S; Krishna Bharat, L; Yu, Jae Su

2017-11-28

We report a flexible battery-type electrode based on binder-free nickel cobalt layered double hydroxide nanosheets adhered to nickel cobalt layered double hydroxide nanoflake arrays on nickel fabric (NC LDH NFAs@NSs/Ni fabric) using facile and eco-friendly synthesis methods. Herein, we utilized discarded polyester fabric as a cost-effective substrate for in situ electroless deposition of Ni, which exhibited good flexibility, light weight, and high conductivity. Subsequently, the vertically aligned NC LDH NFAs were grown on Ni fabric by means of a hot-air oven-based method, and fluffy-like NC LDH NS branches are further decorated on NC LDH NFAs by a simple electrochemical deposition method. The as-prepared core-shell-like nanoarchitectures improve the specific surface area and electrochemical activity, which provides the ideal pathways for electrolyte diffusion and charge transportation. When the electrochemical performance was tested in 1 M KOH aqueous solution, the core-shell-like NC LDH NFAs@NSs/Ni fabric electrode liberated a maximum areal capacity of 536.96 μAh/cm 2 at a current density of 2 mA/cm 2 and excellent rate capability of 78.3% at 30 mA/cm 2 (420.5 μAh/cm 2 ) with a good cycling stability. Moreover, a fabric-based hybrid supercapacitor (SC) was assembled, which achieves a stable operational potential window of 1.6 V, a large areal capacitance of 1147.23 mF/cm 2 at 3 mA/cm 2 , and a high energy density of 0.392 mWh/cm 2 at a power density of 2.353 mW/cm 2 . Utilizing such high energy storage abilities and flexible properties, the fabricated hybrid SC operated the wearable digital watch and electric motor fan for real-time applications.

Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

PubMed

Brooks, Emily K; Tobias, Menachem E; Yang, Shuying; Bone, Lawrence B; Ehrensberger, Mark T

2016-02-01

This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM). The EIS showed both the inner layer resistance (Rin ) and outer layer resistance (Rout ) were lower for samples without cells cultured on the surface at 3 days (Rin  = 2.64 e4 Ω/cm(2) , Rout  = 140 Ω/cm(2) ) compared to 21 days (Rin  = 3.60 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ) due to precipitation of magnesium and calcium phosphates over time. Samples with preosteoblasts cultured on the surface had a slower initial corrosion (3 day, Rin  = 1.88 e5 Ω/cm(2) , Rout  = 1060 Ω/cm(2) ) which was observed to increase over time (21 day, Rin  = 2.99 e4 Ω/cm(2) , Rout  = 287 Ω/cm(2) ). Changes in the corrosion processes were thought to be related to changes in the coverage provided by the cell layer. Our results reveal that the presence of cells and biological processes are able to significantly influence the corrosion rate of AZ91. © 2015 Wiley Periodicals, Inc.

Atomic layer deposition of Al-incorporated Zn(O,S) thin films with tunable electrical properties

NASA Astrophysics Data System (ADS)

Park, Helen Hejin; Jayaraman, Ashwin; Heasley, Rachel; Yang, Chuanxi; Hartle, Lauren; Mankad, Ravin; Haight, Richard; Mitzi, David B.; Gunawan, Oki; Gordon, Roy G.

2014-11-01

Zinc oxysulfide, Zn(O,S), films grown by atomic layer deposition were incorporated with aluminum to adjust the carrier concentration. The electron carrier concentration increased up to one order of magnitude from 1019 to 1020 cm-3 with aluminum incorporation and sulfur content in the range of 0 ≤ S/(Zn+Al) ≤ 0.16. However, the carrier concentration decreased by five orders of magnitude from 1019 to 1014 cm-3 for S/(Zn+Al) = 0.34 and decreased even further when S/(Zn+Al) > 0.34. Such tunable electrical properties are potentially useful for graded buffer layers in thin-film photovoltaic applications.

Study of the amorphization of surface silicon layers implanted by low-energy helium ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lomov, A. A., E-mail: lomov@ftian.ru; Myakon’kikh, A. V.; Oreshko, A. P.

2016-03-15

The structural changes in surface layers of Si(001) substrates subjected to plasma-immersion implantation by (2–5)-keV helium ions to a dose of D = 6 × 10{sup 15}–5 × 10{sup 17} cm{sup –2} have been studied by highresolution X-ray diffraction, Rutherford backscattering, and spectral ellipsometry. It is found that the joint application of these methods makes it possible to determine the density depth distribution ρ(z) in an implanted layer, its phase state, and elemental composition. Treatment of silicon substrates in helium plasma to doses of 6 × 10{sup 16} cm{sup –2} leads to the formation of a 20- to 30-nm-thick amorphizedmore » surface layer with a density close to the silicon density. An increase in the helium dose causes the formation of an internal porous layer.« less

Stretchable Metamaterial Absorber Using Liquid Metal-Filled Polydimethylsiloxane (PDMS)

PubMed Central

Kim, Kyeongseob; Lee, Dongju; Eom, Seunghyun; Lim, Sungjoon

2016-01-01

A stretchable metamaterial absorber is proposed in this study. The stretchability was achieved by liquid metal and polydimethylsiloxane (PDMS). To inject liquid metal, microfluidic channels were fabricated using PDMS powers and microfluidic-channel frames, which were built using a three-dimensional printer. A top conductive pattern and ground plane were designed after considering the easy injection of liquid metal. The proposed metamaterial absorber comprises three layers of PDMS substrate. The top layer is for the top conductive pattern, and the bottom layer is for the meandered ground plane. Flat PDMS layers were inserted between the top and bottom PDMS layers. The measured absorptivity of the fabricated absorber was 97.8% at 18.5 GHz, and the absorption frequency increased from 18.5 to 18.65 GHz as the absorber was stretched from its original length (5.2 cm) to 6.4 cm. PMID:27077861

Investigation of Natural and Man-Made Radiation Effects on Crews on Long Duration Space Missions

NASA Technical Reports Server (NTRS)

Bolch, Wesley E.; Parlos, Alexander

1996-01-01

Over the past several years, NASA has studied a variety of mission scenarios designed to establish a permanent human presence on the surface of Mars. Nuclear electric propulsion (NEP) is one of the possible elements in this program. During the initial stages of vehicle design work, careful consideration must be given to not only the shielding requirements of natural space radiation, but to the shielding and configuration requirements of the on-board reactors. In this work, the radiation transport code MCNP has been used to make initial estimates of crew exposures to reactor radiation fields for a specific manned NEP vehicle design. In this design, three 25 MW(sub th), scaled SP-100-class reactors are shielded by three identical shields. Each shield has layers of beryllium, tungsten, and lithium hydride between the reactor and the crew compartment. Separate calculations are made of both the exiting neutron and gamma fluxes from the reactors during beginning-of-life, full-power operation. This data is then used as the source terms for particle transport in MCNP. The total gamma and neutron fluxes exiting the reactor shields are recorded and separate transport calculations are then performed for a 10 g/sq cm crew compartment aluminum thickness. Estimates of crew exposures have been assessed for various thicknesses of the shield tungsten and lithium hydride layers. A minimal tungsten thickness of 20 cm is required to shield the reactor photons below the 0.05 Sv/y man-made radiation limit. In addition to a 20-cm thick tungsten layer, a 40-cm thick lithium hydride layer is required to shield the reactor neutrons below the annual limit. If the tungsten layer is 30-cm thick, the lithium hydride layer should be at least 30-cm thick. These estimates do not take into account the photons generated by neutron interactions inside the shield because the MCNP neutron cross sections did not allow reliable estimates of photon production in these materials. These results, along with natural space radiation shielding estimates calculated by NASA Langley Research Center, have been used to provide preliminary input data into a new Macintosh-based software tool. A skeletal version of this tool being developed will allow rapid radiation exposure and risk analyses to be performed on a variety of Lunar and Mars missions utilizing nuclear-powered vehicles.

Possible forerunners of earthquakes in optical range

NASA Astrophysics Data System (ADS)

Malnev, V. N.; Martysh, E. V.; Koshevya, S.; Kotsarenko, A.; Siqueiros Alatorre, J.

2007-05-01

The monitoring of the electrostatic field on the eve of the strong earthquakes detect its ultra-low-frequency perturbations with a period of a few hours (10-4Hz) and a magnitude of the order of 10 V/cm. Usually this field is on the level of one V/cm. The anomalous electric field as a forerunner of the coming earthquake considerably increases a concentration of the metal ions (sodium) in the E-domain at altitudes ~120 km and the electron concentration, as well. In particular, the latter may enlarge by one order comparing with the initial electron concentration in this domain. The typical dimensions of this layer are ~ 100 km in a length and ~ 10 km in a thickness. The perturbations of this electric field form a layer with higher than usual concentration of sodium ions and atoms in the E- ionosphere and the field will heats-up electrons in this layer. Simple evaluations show the electron temperature in this layer in the presence of the seismogenic electric field is approximately about 1000-1300K at altitudes 100-120 km provided that the electric field is ~ 10-3 V/cm. It is important the cross-section of excitation of the nitrogen low vibration levels by electrons at this energy is anomalous and close to 5x10-15cm2. It happens to be that the eighth vibration level of a nitrogen molecule practically coincides with the first excited state of a sodium atom with energy ENa=2.1eV. Thus, the resonant transfer of the vibration energy of excited nitrogen with excitation of a sodium atom takes place practically in every collision. Our evaluation of the sodium doublet intensity due to the above-discussed mechanism from the ionosphere layer, mentioned above, gives 5x10-3erg/cm2s. A comparison of this quantity with the conventional intensity of the sodium doublet from this layer 7x10-4erg/cm2s shows that the suggested mechanism provides the intensity almost by one order larger than the conventional intensity of the sodium doublet. The considerable increasing in the intensity of the sodium doublet in the spectrum of the night ionosphere can be registered by monitoring the night sky over the seismic dangerous regions.

Zinc movement in sewage-sludge-treated soils as influenced by soil properties, irrigation water quality, and soil moisture level

USGS Publications Warehouse

Welch, J.E.; Lund, L.J.

1989-01-01

A soil column study was conducted to assess the movement of Zn in sewage-sludge-amended soils. Varables investigated were soil properties, irrigation water quality, and soil moisture level. Bulk samples of the surface layer of six soil series were packed into columns, 10.2 cm in diameter and 110 cm in length. An anaerobically digested municipal sewage sludge was incorporated into the top 20 cm of each column at a rate of 300 mg ha-1. The columns were maintained at moisture levels of saturation and unsaturation and were leached with two waters of different quality. At the termination of leaching, the columns were cut open and the soil was sectioned and analyzed. Zinc movement was evaluated by mass balance accounting and correlation and regression analysis. Zinc movement in the unsaturated columns ranged from 3 to 30 cm, with a mean of 10 cm. The difference in irrigation water quality did not have an effect on Zn movement. Most of the Zn applied to the unsaturated columns remained in the sludge-amended soil layer (96.1 to 99.6%, with a mean of 98.1%). The major portion of Zn leached from the sludge-amended soil layer accumulated in the 0- to 3-cm depth (35.7 to 100%, with a mean of 73.6%). The mean final soil pH values decreased in the order: saturated columns = sludge-amended soil layer > untreated soils > unsaturated columns. Total Zn leached from the sludge-amended soil layer was correlated negatively at P = 0.001 with final pH (r = -0.85). Depth of Zn movement was correlated negatively at P = 0.001 with final pH (r = -0.91). Multiple linear regression analysis showed that the final pH accounted for 72% of the variation in the total amounts of Zn leached from the sludge-amended soil layer of the unsaturated columns and accounted for 82% of the variation in the depth of Zn movement among the unsaturated columns. A significant correlation was not found between Zn and organic carbon in soil solutions, but a negative correlation significant at P = 0.001 was found between pH and Zn (r = -0.61).

Second generation large area microchannel plate flat panel phototubes

NASA Astrophysics Data System (ADS)

Ertley, C. D.; Siegmund, O. H. W.; Jelinsky, S. R.; Tedesco, J.; Minot, M. J.; O'Mahony, A.; Craven, C. A.; Popecki, M.; Lyashenko, A. V.; Foley, M. R.

2016-07-01

Very large (20 cm × 20 cm) flat panel phototubes are being developed which employ novel microchannel plates (MCPs). The MCPs are manufactured using borosilicate microcapillary arrays which are functionalized by the application of resistive and secondary emissive layers using atomic layer deposition (ALD). This allows the operational parameters to be set by tailoring sequential ALD deposition processes. The borosilicate substrates are robust, including the ability to be produced in large formats (20 cm square). ALD MCPs have performance characteristics (gain, pulse amplitude distributions, and imaging) that are equivalent or better than conventional MCPs. They have low intrinsic background (0.045 events cm-2 sec-1)., high open area ratios (74% for the latest generation of borosilicate substrates), and stable gain during >7 C cm-2 charge extraction after preconditioning (vacuum bake and burn-in). The tube assemblies use a pair of 20 cm × 20 cm ALD MCPs comprised of a borosilicate entrance window, a proximity focused bialkali photocathode, and a strip-line readout anode. The second generation design employs an all glass body with a hot indium seal and a transfer photocathode. We have achieved >20% quantum efficiency and good gain uniformity over the 400 cm2 field of view, spatial resolution of <1 cm and obtained event timing accuracy of close to 100 ps FWHM.

Changes in physical properties and carbon stocks of gray forest soils in the southern part of Moscow region during postagrogenic evolution

NASA Astrophysics Data System (ADS)

Baeva, Yu. I.; Kurganova, I. N.; Lopes de Gerenyu, V. O.; Pochikalov, A. V.; Kudeyarov, V. N.

2017-03-01

Changes in carbon stocks and physical properties of gray forest soils during their postagrogenic evolution have been studied in the succession chronosequence comprising an arable, lands abandoned 6, 15, and 30 years ago; and a secondary deciduous forest (Experimental Field Station of the Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Moscow region). It is found that carbon stocks in the upper 60-cm soil layer gain with increasing period of abandonment, from 6.17 kg C/m2 on the arable land to 8.81 kg C/m2 in the forest soil, which represents the final stage of postagrogenic succession. The most intensive carbon accumulation occurs in the upper layer of the former plow (0- to 10-cm) horizon. It is shown that the self-restoration of gray forest soils is accompanied by a reliable decrease of bulk density in the upper 10-cm layer from 1.31 ± 0.01 g/cm3 on the arable to 0.97 ± 0.02 g/cm3 in the forest. In the former plow horizon of the arable-abandoned land-forest succession series, the portion of macroaggregates increases from 73.6 to 88.5%; the mean weighted diameter of aggregates, by 1.6 times; and the coefficient of aggregation, by 3.8 times. Thus, the removal of lands from agricultural use results in a gradual restoration of their natural structure, improvement of soil agronomical properties, and carbon sequestration in the upper part of the soil profile.

ITO/Au/ITO sandwich structure for near-infrared plasmonics.

PubMed

Fang, Xu; Mak, Chee Leung; Dai, Jiyan; Li, Kan; Ye, Hui; Leung, Chi Wah

2014-09-24

ITO/Au/ITO trilayers with varying gold spacer layer thicknesses were deposited on glass substrates by pulsed laser deposition. Transmission electron microscopy measurements demonstrated the continuous nature of the Au layer down to 2.4 nm. XRD patterns clearly showed an enhanced crystallinity of the ITO films promoted by the insertion of the gold layer. Compared with a single layer of ITO with a carrier concentration of 7.12 × 10(20) cm(-3), the ITO/Au/ITO structure achieved an effective carrier concentration as high as 3.26 × 10(22) cm(-3). Transmittance and ellipsometry measurements showed that the optical properties of ITO/Au/ITO films were greatly influenced by the thickness of the inserted gold layer. The cross-point wavelength of the trilayer samples was reduced with increasing gold layer thickness. Importantly, the trilayer structure exhibited a reduced loss (compared with plain Au) in the near-infrared region, suggesting its potential for plasmonic applications in the near-infrared range.

Enhanced interfacial electron transfer of inverted perovskite solar cells by introduction of CoSe into the electron-transporting-layer

NASA Astrophysics Data System (ADS)

Chen, Shanshan; Yang, Songwang; Sun, Hong; Zhang, Lu; Peng, Jiajun; Liang, Ziqi; Wang, Zhong-Sheng

2017-06-01

To improve the electron transfer at the interface between the perovskite film and the electron-transporting-material (ETM) layer, CoSe doped [6,6]-phenyl C61-butyric acid methyl ester (PCBM) is employed as the ETM layer for the inverted planar perovskite solar cell with NiO as the hole-transporting-material layer. Introduction of CoSe (5.8 wt%) into the PCBM layer improves the conductivity of the ETM layer and decreases the photoluminescence intensity, thus enhancing the interfacial electron extraction and reducing the electron transfer resistance at the perovskite/ETM interface. As a consequence, the power conversion efficiency is enhanced from 11.43% to 14.91% by 30% due to the noted increases in short-circuit current density from 17.95 mA cm-2 to 19.85 mA cm-2 and fill factor from 0.60 to 0.70. This work provides a new strategy to improve the performance of inverted perovskite solar cells.

Epitaxial growth of YBa2Cu3O7 - delta films on oxidized silicon with yttria- and zirconia-based buffer layers

NASA Astrophysics Data System (ADS)

Pechen, E. V.; Schoenberger, R.; Brunner, B.; Ritzinger, S.; Renk, K. F.; Sidorov, M. V.; Oktyabrsky, S. R.

1993-09-01

A study of epitaxial growth of YBa2Cu3O7-δ films on oxidized Si with yttria- and zirconia-based buffer layers is reported. Using substrates with either SiO2 free or naturally oxidized (100) surfaces of Si it was found that a thin SiO2 layer on top of the Si favors high-quality superconducting film formation. Compared to yttria-stabilized ZrO2 (YSZ) single layers, YSZY2O3 double and YSZ/Y2O3YSZ triple layers allows the deposition of thin YBa2Cu3O7-δ films with improved properties including reduced aging effects. In epitaxial YBa2Cu3O7-δ films grown on the double buffer layers a critical temperature Tc(R=0)=89.5 K and critical current densities of 3.5×106 A/cm2 at 77 K and 1×107 A/cm2 at 66 K were reached.

Work Function Variations in Twisted Graphene Layers

DOE PAGES

Robinson, Jeremy T.; Culbertson, James; Berg, Morgann; ...

2018-01-31

By combining optical imaging, Raman spectroscopy, kelvin probe force microscopy (KFPM), and photoemission electron microscopy (PEEM), we show that graphene’s layer orientation, as well as layer thickness, measurably changes the surface potential (Φ). Detailed mapping of variable-thickness, rotationally-faulted graphene films allows us to correlate Φ with specific morphological features. Using KPFM and PEEM we measure ΔΦ up to 39 mV for layers with different twist angles, while ΔΦ ranges from 36–129 mV for different layer thicknesses. The surface potential between different twist angles or layer thicknesses is measured at the KPFM instrument resolution of ≤ 200 nm. The PEEM measuredmore » work function of 4.4 eV for graphene is consistent with doping levels on the order of 10 12cm -2. Here, we find that Φ scales linearly with Raman G-peak wavenumber shift (slope = 22.2 mV/cm -1) for all layers and twist angles, which is consistent with doping-dependent changes to graphene’s Fermi energy in the ‘high’ doping limit. Our results here emphasize that layer orientation is equally important as layer thickness when designing multilayer two-dimensional systems where surface potential is considered.« less

Work Function Variations in Twisted Graphene Layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Jeremy T.; Culbertson, James; Berg, Morgann

By combining optical imaging, Raman spectroscopy, kelvin probe force microscopy (KFPM), and photoemission electron microscopy (PEEM), we show that graphene’s layer orientation, as well as layer thickness, measurably changes the surface potential (Φ). Detailed mapping of variable-thickness, rotationally-faulted graphene films allows us to correlate Φ with specific morphological features. Using KPFM and PEEM we measure ΔΦ up to 39 mV for layers with different twist angles, while ΔΦ ranges from 36–129 mV for different layer thicknesses. The surface potential between different twist angles or layer thicknesses is measured at the KPFM instrument resolution of ≤ 200 nm. The PEEM measuredmore » work function of 4.4 eV for graphene is consistent with doping levels on the order of 10 12cm -2. Here, we find that Φ scales linearly with Raman G-peak wavenumber shift (slope = 22.2 mV/cm -1) for all layers and twist angles, which is consistent with doping-dependent changes to graphene’s Fermi energy in the ‘high’ doping limit. Our results here emphasize that layer orientation is equally important as layer thickness when designing multilayer two-dimensional systems where surface potential is considered.« less

Control of the inversion-channel MOS properties by Mg doping in homoepitaxial p-GaN layers

NASA Astrophysics Data System (ADS)

Takashima, Shinya; Ueno, Katsunori; Matsuyama, Hideaki; Inamoto, Takuro; Edo, Masaharu; Takahashi, Tokio; Shimizu, Mitsuaki; Nakagawa, Kiyokazu

2017-12-01

Lateral GaN MOSFETs on homoepitaxial p-GaN layers with different Mg doping concentrations ([Mg]) have been evaluated to investigate the impact of [Mg] on MOS channel properties. It is demonstrated that the threshold voltage (V th) can be controlled by [Mg] along with the theoretical curve. The field effect mobility also shows [Mg] dependence and a maximum field effect mobility of 123 cm2 V-1 s-1 is achieved on [Mg] = 6.5 × 1016 cm-3 layer with V th = 3.0 V. The obtained results indicate that GaN MOSFETs can be designed on the basis of the doping concentration of the p-GaN layer with promising characteristics for the realization of power MOSFETs.

Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone

NASA Astrophysics Data System (ADS)

Johnson, Kristofer D.; Harden, Jennifer W.; McGuire, A. David; Clark, Mark; Yuan, Fengming; Finley, Andrew O.

2013-09-01

Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic factors were investigated using structural equation modeling in a multi-group analysis. Groups were defined by slope, soil texture type, and shallow (<28 cm) versus deep organic (≥28 cm) layers. The probability of observing permafrost sharply increased by 0.32 for every 10-cm OLT increase in shallow OLT soils (OLTs) due to an insulation effect, but PF decreased in deep OLT soils (OLTd) by 0.06 for every 10-cm increase. Across the MAT gradient, PF in sandy soils varied little, but PF in loamy and silty soils decreased substantially from cooler to warmer temperatures. The change in OLT was more heterogeneous across soil texture types—in some there was no change while in others OLTs soils thinned and/or OLTd soils thickened at warmer locations. Furthermore, when soil organic carbon was estimated using a relationship with thickness, the average increase in carbon in OLTd soils was almost four times greater compared to the average decrease in carbon in OLTs soils across all soil types. If soils follow a trajectory of warming that mimics the spatial gradients found today, then heterogeneities of permafrost degradation and organic layer thinning and thickening should be considered in the regional carbon balance.

Permafrost and organic layer interactions over a climate gradient in a discontinuous permafrost zone

USGS Publications Warehouse

Johnson, Kristofer D.; Harden, Jennifer W.; McGuire, A. David; Clark, Mark; Yuan, Fengming; Finley, Andrew O.

2013-01-01

Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic factors were investigated using structural equation modeling in a multi-group analysis. Groups were defined by slope, soil texture type, and shallow (<28 cm) versus deep organic (≥28 cm) layers. The probability of observing permafrost sharply increased by 0.32 for every 10-cm OLT increase in shallow OLT soils (OLTs) due to an insulation effect, but PF decreased in deep OLT soils (OLTd) by 0.06 for every 10-cm increase. Across the MAT gradient, PF in sandy soils varied little, but PF in loamy and silty soils decreased substantially from cooler to warmer temperatures. The change in OLT was more heterogeneous across soil texture types—in some there was no change while in others OLTs soils thinned and/or OLTd soils thickened at warmer locations. Furthermore, when soil organic carbon was estimated using a relationship with thickness, the average increase in carbon in OLTd soils was almost four times greater compared to the average decrease in carbon in OLTs soils across all soil types. If soils follow a trajectory of warming that mimics the spatial gradients found today, then heterogeneities of permafrost degradation and organic layer thinning and thickening should be considered in the regional carbon balance.

Winter Chickadees

ERIC Educational Resources Information Center

Sarvis, Gisele Winton

2010-01-01

Hiking between the farmer's field and the deciduous forest at Scanlon Creek Nature Centre near Bradford, Ontario, a grade 3 class and the author were studying different types of soils. As soil explorers they were hiking to different locations to see, touch and smell clay, silt and humus soils. The author always likes to bring a sense of discovery…

Cultivating Writers: Figurative Language in the Developmental Class

ERIC Educational Resources Information Center

Nelson, Alexis

2012-01-01

Some teaching strategies grow out of the curricula educators inherit or develop through professional reading; others originate in the aromatic humus of their autobiographies. This article presents a proposal that has its origins in the latter. The author recognized that what delights her in prose or poetry is the figurative language a writer uses…