Science.gov

Sample records for 0-30 cm soil

  1. Mid-continent fall temperatures at the 10-cm soil depth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recommendations for applying N-fertilizer in autumn involve delaying applications until daily soil temperature at 10 cm depth is = or < 10° C. Daily soil temperature data during autumn were examined from 26 sites along a transect from 36° to 49° N latitude in the mid-continent USA. After soils first...

  2. 28 CFR 0.30 - General functions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 28 Judicial Administration 1 2013-07-01 2013-07-01 false General functions. 0.30 Section 0.30 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Community Relations Service § 0.30 General functions. The following-described matters are assigned to, and shall be...

  3. Numerical simulation of soil brightness temperatures at wavelength of 21 cm

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.

    1981-01-01

    A simulation model is applied to reproduce some observed brightness temperatures at a wavelength of 21 cm. The simulated results calculated with two different soil textures are compared directly with observations measured over fields in Arizona and South Dakota. It is found that good agreement is possible by properly adjusting the surface roughness parameter. Correlation analysis and linear regression of the brightness temperatures versus soil moistures are also carried out.

  4. Estimation of CO2 diffusion coefficient at 0-10 cm depth in undisturbed and tilled soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diffusion coefficients (D) of CO2 at 0 – 10 cm layers in undisturbed and tilled soil conditions were estimated using Penman, Millington-Quirk, Ridgwell et al. (1999), Troeh et al., and Moldrup et al. models. Soil bulk density and volumetric soil water content ('v) at 0 – 10 cm were measured on April...

  5. Biocrusts serve as biomarkers for the upper 30 cm soil water content

    NASA Astrophysics Data System (ADS)

    Kidron, Giora J.; Benenson, Itzhak

    2014-02-01

    Knowledge regarding the spatial distribution of moisture in soil is of great importance especially in arid regions where water is scarce. Following a previous research that showed a significant relationship between daylight surface wetness duration and the average chlorophyll content of 5 biocrusts in the Negev Desert (Israel), and the resultant outcome that pointed to the possible use of biocrusts as biomarkers for surface wetness duration, we hypothesize that biocrusts may also serve as biomarkers for the moisture content of the upper soil layer. Toward this end, daylight surface wetness duration was measured at 5 crust types following rain events during 1993-1995 along with periodical soil sampling of the upper 30 cm (at 5 cm intervals) of the soil profiles underlying these biocrusts. The findings showed a positive linear relationship between daylight surface wetness duration and the chlorophyll content of the crusts (r2 = 0.96-0.97). High correlations were also found between daylight surface wetness duration and the available water content (r2 = 0.96) and duration (r2 = 0.85-0.88) of the upper 30 cm soil and between the chlorophyll content of the crust and the available water content (r2 = 0.93-0.96) and duration (r2 = 0.78-0.84). Topography-induced shading and slope position (which determined additional water either by runoff or subsurface flow) are seen responsible for the clear link between subsurface moisture content, daylight surface wetness duration and chlorophyll content of the crust. This link points to the possible use of biocrusts as biomarkers for subsurface water content and highlights the importance of crust typology and mapping for the study of the spatial distribution of water and their potential use for the study of ecosystem structure and function.

  6. A case study demonstration of the soil temperature extrema recovery rates after precipitation cooling at 10-cm soil depth

    NASA Technical Reports Server (NTRS)

    Welker, Jean Edward

    1991-01-01

    Since the invention of maximum and minimum thermometers in the 18th century, diurnal temperature extrema have been taken for air worldwide. At some stations, these extrema temperatures were collected at various soil depths also, and the behavior of these temperatures at a 10-cm depth at the Tifton Experimental Station in Georgia is presented. After a precipitation cooling event, the diurnal temperature maxima drop to a minimum value and then start a recovery to higher values (similar to thermal inertia). This recovery represents a measure of response to heating as a function of soil moisture and soil property. Eight different curves were fitted to a wide variety of data sets for different stations and years, and both power and exponential curves were fitted to a wide variety of data sets for different stations and years. Both power and exponential curve fits were consistently found to be statistically accurate least-square fit representations of the raw data recovery values. The predictive procedures used here were multivariate regression analyses, which are applicable to soils at a variety of depths besides the 10-cm depth presented.

  7. Effects of modified soil water-heat physics on RegCM4 simulations of climate over the Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Wang, Xuejia; Pang, Guojin; Yang, Meixue; Wan, Guoning

    2016-06-01

    To optimize the description of land surface processes and improve climate simulations over the Tibetan Plateau (TP), a modified soil water-heat parameterization scheme (SWHPS) is implemented into the Community Land Model 3.5 (CLM3.5), which is coupled to the regional climate model 4 (RegCM4). This scheme includes Johansen's soil thermal conductivity scheme together with Niu's groundwater module. Two groups of climate simulations are then performed using the original RegCM4 and revised RegCM4 to analyze the effects of the revised SWHPS on regional climate simulations. The effect of the revised RegCM4 on simulated air temperature is relatively small (with mean biases changing by less than 0.1°C over the TP). There are overall improvements in the simulation of winter and summer air temperature but increased errors in the eastern TP. It has a significant effect on simulated precipitation. There is also a clear improvement in simulated annual and winter precipitation, particularly over the northern TP, including the Qilian Mountains and the source region of the Yellow River. There are, however, increased errors in precipitation simulation in parts of the southern TP. The precipitation difference between the two models is caused mainly by their convective precipitation difference, particularly in summer. Overall, the implementation of the new SWHPS into the RegCM4 has a significant effect not only on land surface variables but also on the overlying atmosphere through various physical interactions.

  8. Assessing potential of vertical average soil moisture (0-40cm) estimation for drought monitoring using MODIS data: a case study

    NASA Astrophysics Data System (ADS)

    Ma, Jianwei; Huang, Shifeng; Li, Jiren; Li, Xiaotao; Song, Xiaoning; Leng, Pei; Sun, Yayong

    2015-12-01

    Soil moisture is an important parameter in the research of hydrology, agriculture, and meteorology. The present study is designed to produce a near real time soil moisture estimation algorithm by linking optical/IR measurements to ground measured soil moisture, and then used to monitoring region drought. It has been found that the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) are related to surface soil moisture. Therefore, a relationship between ground measurement soil moisture and NDVI and LST can be developed. Six days' NDVI and LST data calculated from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) of Shandong province during October in 2009 to May in 2010 were combined with ground measured volumetric soil moisture in different depth (10cm, 20cm, 40cm, and mean in vertical (0-40cm)) and different soil type to determine regression relationships at a 1 km scale. Based on the regression relationships, mean volumetric soil moisture in vertical (0-40cm) at 1 km resolution can be calculated over the Shandong province, and then drought maps were obtained. The result shows that significantly relationship exists between the NDVI and LST and soil moisture at different soil depths, and regression relationships are soil type dependent. What is more, the drought monitoring results agree well with actual situation.

  9. Comparison of 2.8- and 21-cm microwave radiometer observations over soils with emission model calculations

    NASA Technical Reports Server (NTRS)

    Burke, W. J.; Schmugge, T.; Paris, J. F.

    1979-01-01

    An airborne experiment was conducted under NASA auspices to test the feasibility of detecting soil moisture by microwave remote sensing techniques over agricultural fields near Phoenix, Arizona at midday of April 5, 1974 and at dawn of the following day. Extensive ground data were obtained from 96 bare, sixteen hectare fields. Observations made using a scanning (2.8 cm) and a nonscanning (21 cm) radiometer were compared with the predictions of a radiative transfer emission model. It is shown that (1) the emitted intensity at both wavelengths correlates best with the near surface moisture, (2) surface roughness is found to more strongly affect the degree of polarization than the emitted intensity, (3) the slope of the intensity-moisture curves decreases in going from day to dawn, and (4) increased near surface moisture at dawn is characterized by increased polarization of emissions. The results of the experiment indicate that microwave techniques can be used to observe the history of the near surface moisture. The subsurface history must be inferred from soil physics models which use microwave results as boundary conditions.

  10. Carbon stocks of dead wood, litter, and soil in the forest sector in Japan estimated by the National Forest Soil Carbon Inventory

    NASA Astrophysics Data System (ADS)

    Nanko, Kazuki; Ugawa, Shin; Takahashi, Masamichi; Morisada, Kazuhito; Takeuchi, Manabu; Matuura, Yojiro; Yoshinaga, Shuichiro; Araki, Makoto; Tanaka, Nagaharu; Ikeda, Shigeto; Miura, Satoru; Ishizuka, Shigehiro; Kobayashi, Masahiro; Inagaki, Masahiro; Imaya, Akihiro; Hashimoto, Shoji; Kaneko, Shinji

    2013-04-01

    The carbon (C) stocks of dead wood, litter, and soil are the basic data for evaluating the C sink function in the forest sector in Japan. We estimated the C stocks of dead wood, litter, and soil at 0-30 cm in the forest sector in Japan and clarified the spatial distribution of those C stocks according to region units. Data were collected in 2438 survey plots in FY 2006-2010 by the National Forest Soil Carbon Inventory Project, which surveyed the C stocks of dead wood, litter, and soil at 0-30 cm throughout the forest sector in Japan. The C stock (mean ± sample standard deviation) of dead wood, litter, and soil at 0-30 cm was 0.42 ± 0.67, 0.49 ± 0.32, and 6.94 ± 3.25 kg m-2, respectively. The C stock of soil at 0-30 cm was slightly lower than previous study in Japan. The difference might be attributed to the difference of the sampling methodologies. The C stocks of the three pools were significantly different among regions. Although temperature influenced the tendency in the distribution of the C stocks among regions of dead wood and litter, the tendency was not unidirectional. On the other hand, the C stock of soil at 0-30 cm was higher in northern Japan and lower in southern Japan, although high C stock was observed in some regions in the volcanic region of southern Japan. Thus, we suggest that the soil C stock at 0-30 cm is regulated by macro scale factors such as temperature as well as by the distribution of volcanic ash soils. The part of this study is published in Ugawa et al. (2012, Bull. FFPRI. 11, 207-221).

  11. Photosynthetic water use efficiency and biomass of Sorghastrum nutans (C4) and Solidago canadensis (C3) in three soils along a CO2 concentration gradient

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The water use efficiency (WUE) of leaf photosynthetic carbon uptake is a key regulator of plant production in grasslands. However WUE may differ with soil type because of differences in soil moisture retention and plant uptake efficiency. We measured soil water content (SWC, 0-30 cm, %), leaf-leve...

  12. Investigation of a hydrogen implantation-induced blistering phenomenon in Si0.70Ge0.30

    NASA Astrophysics Data System (ADS)

    Singh, R.; Scholz, R.; Christiansen, S.; Mantl, S.; Reiche, M.

    2011-12-01

    The blistering phenomenon in hydrogen implanted and annealed Si0.70Ge0.30(0 0 1) layers was investigated. The implantation was performed with 240 keV H2+ ions with a fluence of 5 × 1016 cm-2. The blistering kinetics of H-implanted Si0.70Ge0.30 showed two different activation energies: about 1.60 eV in the lower temperature regime (350-425 °C) and 0.40 eV in the higher temperature regime (425-700 °C). Microstructural characterization of the implantation damage in SiGe layers using transmission electron microscopy revealed a damage band extending between 900 and 1200 nm below the surface. It was observed that after post-implantation annealing, a number of platelets and microcracks were formed within the damage band. These extended defects are predominantly oriented parallel to the surface, i.e. in the (0 0 1) plane. However, the extended defects oriented along the {1 1 1} planes were also observed and the density of these defects was the highest toward the end of the damage band. These experimental observations are compared with similar investigations in Si and Ge performed earlier and a plausible explanation for the blistering results in Si0.70Ge0.30 is presented in this work.

  13. State of radionuclides in soils of the eastern-urals radioactive trace

    SciTech Connect

    Martyushov, V.V.; Spirin, D.A.; Bazylev, V.V.

    1995-03-01

    Data on the distribution of long-living radionuclides in a 0-30-cm layer of different types of soils, contaminated as a result of the accident in 1957, are given. Forms of the state and existence of radionuclides in soils are considered in detail. It was determined that distribution of radionuclides and forms of their state and whereabouts in soils depend both on the properties of radionuclides and on soil type.

  14. Manure and nitrogen application enhances soil phosphorus mobility in calcareous soil in greenhouses.

    PubMed

    Yan, Zhengjuan; Chen, Shuo; Li, Junliang; Alva, Ashok; Chen, Qing

    2016-10-01

    Over many years, high phosphorus (P) loading for intensive vegetable cropping in greenhouses of North China has contributed to excessive P accumulation, resulting in environmental risk. In this study, the influences of manure and nitrogen (N) application on the transformation and transport of soil P were investigated after nine years in a greenhouse tomato double cropping system (winter-spring and autumn-winter seasons). High loading of manure significantly increased the soil inorganic P (Pi), inositol hexakisphosphate (IHP), mobile P and P saturation ratio (PSR, >0.7 in 0-30 cm depth soil; PSR was estimated from P/(Fe + Al) in an oxalate extract of the soil). The high rate of N fertilizer application to the studied calcareous soil with heavy loading of manure increased the following: (i) mobile organic P (Po) and Pi fractions, as evidenced by the decrease in the ratio of monoesters to diesters and the proportion of stable Pi (i.e., HCl-Pi) in total P (Pt) in 0-30 cm depth soil; (ii) relative distribution of Po in the subsoil layer; and (iii) P leaching to soil depths below 90 cm and the proportion of Po in Pt in the leachate. More acidic soil due to excessive N application increased P mobility and leaching. The increase in Ox-Al (oxalate-extractable Al) and the proportion of microbe-associated Po related to N application at soil depths of 0-30 cm suggested decrease in the net Po mineralization, which may contribute to downward transport of Po in the soil profile. PMID:27300290

  15. Chernobyl fallout in the uppermost (0-3 cm) humus layer of forest soil in Finland, North East Russia and the Baltic countries in 2000--2003.

    PubMed

    Ylipieti, J; Rissanen, K; Kostiainen, E; Salminen, R; Tomilina, O; Täht, K; Gilucis, A; Gregorauskiene, V

    2008-12-15

    The situation resulting from the Chernobyl fallout in 1987 was compared to that in 2000--2001 in Finland and NW Russia and that in 2003 in the Baltic countries. 786 humus (0-3 cm layer) samples were collected during 2000--2001 in the Barents Ecogeochemistry Project, and 177 samples in the Baltic countries in 2003. Nuclides emitting gamma-radiation in the 0-3 cm humus layer were measured by the Radiation and Nuclear Safety Authority-STUK in Finland. In 1987 the project area was classified by the European Commission into four different fallout classes. 137Cs inventory Bg/m2 levels measured in 2000--2003 were compared to the EU's class ranges. Fitting over the whole project area was implemented by generalizing the results for samples from the Baltic countries, for which Bq/m2 inventories could be calculated. A rough estimation was made by comparing the mass of organic matter and humus with 137Cs concentrations in these two areas. Changes in 137Cs concentration levels are illustrated in both thematic maps and tables. Radionuclide 137Cs concentrations (Bq/kg d.w.) were detected in the humus layer at all the 988 sampling sites. 134Cs was still present in 198 sites 15 years after the nuclear accident in Chernobyl. No other anthropogenic nuclides emitting gamma-radiation were detected, but low levels of 60Co, 125Sb and 154Eu isotopes were found in 14 sites. Fifteen years after the Chernobyl accident, the radioactive nuclide 137Cs was and still is the most significant fallout radionuclide in the environment and in food chains. The results show that the fallout can still be detected in the uppermost humus layer in North East Europe. PMID:18845315

  16. Implementation of i-line lithography to 0.30 um design rules

    NASA Astrophysics Data System (ADS)

    Kim, KeunYoung; Kim, Hung-Eil; Lee, Il-Ho; Kim, Jin-Soo; Chun, Jun-Sung; Hur, Ikboum; Moon, Seung-Chan; Baik, Ki-Ho; Choi, Soo-Han

    1995-05-01

    The optical lithography is extending its life by combining high numerical aperture (NA) optics and shorter wavelength. The shorter wavelength lithography has required the new developments of related technologies. In particular, DUV resists require an entirely different resist chemistry. Much progress has been demonstrated in the field of transparent chemically amplified resists with high sensitivity. However, this DUV lithography ((lambda) equals 248 nm) has been delayed for mass production due to their limitations, such as (i) delay time effects, (ii) high cost ownership due to expensive resist materials and laser maintenance, and (iii) critical dimension (CD) variation over topography caused by multireflection of topographic features. On the other hand, i- line lithography ((lambda) equals 365 nm) has apparently been applied to 64M DRAM of 0.35 micrometers design rule, and attempted to 0.30 micrometers technology which corresponds to 2nd generation 64M DRAM or 1st generation 256 M DRAM. It might be achieved by combination of off-axis illumination (OAI), phase shift mask (PMS) and advanced resist process technique of i-line lithography. Therefore, i-line lithography can be more practical method rather than DUV lithography for the mass production. In this paper, we have optimized the i-line lithographic techniques for the various pattern shape and density for 0.30 micrometers design rule. Optimum duty ratio was tried to find for line and space, contact hole patterns. The basic rule is to keep the minimum Cr width over 0.30 micrometers mask. OAI have been applied to get higher contrast of line and space, and even contact hole patterns, and achieve good pattern fidelities of island patterns. By the implementation of OAI, process latitudes were greatly improved compared to that of conventional techniques. In order to optimize the process over the actual topography, optimum numerical aperture (NA) and aperture of the OAI were selected. In conclusion, 0.30 micrometers

  17. Plasma arc welding Hp-9Ni-4Co-0.30C steel

    SciTech Connect

    Harwig, D.D.; Hunt, J.F.; Theus, G.J.

    1994-12-31

    The plasma arc welding process is used to fabricate the advanced solid rocket motor (ASRM) casing for the Space Shuttle. Plasma arc welding (PAW) was chosen because this process assures a full penetration root pass with the keyhole mode. The HP 9Ni-4Co-0.30C steel was chosen for the ASRM application because the material has excellent strength, toughness, and weldability. The minimum mechanical property requirements of the weldment are 190 ksi yield, 205 ksi ultimate, 8% elongation, 25% reduction in area and 90 ksi/in. fracture toughness. Therefore, a comprehensive development plan was performed to fully characterize plasma arc welding HP 9Ni-4Co-0.30 steel. The test technique systematically varied the essential plasma arc parameters: current, travel speed, plasma gas or wire feed speed while maintaining constant arc length and torch set-up conditions. This PWHT produced the best combination of strength, toughness, and acceptable residual stresses. Variations in land thickness, plasma gas flow rate, current, travel speed, and arc length were characterized by measuring weld bead shape geometry. The weld procedure was found to be tolerant to rather wide parameter variations.

  18. SOIL-PROFILE ORGANIC CARBON AND TOTAL NITROGEN UNDER BERMUDAGRASS MANAGEMENT IN THE SOUTHERN PIEDMONT USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimates of potential carbon (C) and nitrogen (N) sequestration at depths below the traditional plow layer (0-30 cm) are limited, but are needed to improve our understanding of management influences on greenhouse gas emissions and nutrient cycling. Soil samples were collected under `Coastal' bermud...

  19. The resolved magnetic fields of the quiescent cloud GRSMC 45.60+0.30

    NASA Astrophysics Data System (ADS)

    Pavel, Michael D.; Marchwinski, Robert C.; Clemens, Dan P.

    2015-03-01

    Marchwinski et al. (2012) mapped the magnetic field strength across the quiescent cloud GRSMC 45.60+0.30 (shown in Figure 1 subtending 40x10 pc at a distance of 1.88 kpc) with the Chandrasekhar-Fermi method CF; Chandrasekhar & Fermi 1953) using near-infrared starlight polarimetry from the Galactic Plane Infrared Polarization Survey (Clemens et al. 2012a, b) and gas properties from the Galactic Ring Survey (Jackson et al. 2006). The large-scale magnetic field is oriented parallel to the gas-traced `spine' of the cloud. Seven `magnetic cores' with high magnetic field strength were identified and are coincident with peaks in the gas column density. Calculation of the mass-to-flux ratio (Crutcher 1999) shows that these cores are exclusively magnetically subcritical and that magnetostatic pressure can support them against gravitational collapse.

  20. Ubiquitous CM and DM

    NASA Technical Reports Server (NTRS)

    Crowley, Sandra L.

    2000-01-01

    Ubiquitous is a real word. I thank a former Total Quality Coach for my first exposure some years ago to its existence. My version of Webster's dictionary defines ubiquitous as "present, or seeming to be present, everywhere at the same time; omnipresent." While I believe that God is omnipresent, I have come to discover that CM and DM are present everywhere. Oh, yes; I define CM as Configuration Management and DM as either Data or Document Management. Ten years ago, I had my first introduction to the CM world. I had an opportunity to do CM for the Space Station effort at the NASA Lewis Research Center. I learned that CM was a discipline that had four areas of focus: identification, control, status accounting, and verification. I was certified as a CMIl graduate and was indoctrinated about clear, concise, and valid. Off I went into a world of entirely new experiences. I was exposed to change requests and change boards first hand. I also learned about implementation of changes, and then of technical and CM requirements.

  1. Superconductivity of amorphous Mg 0.70Zn 0.30-xGa x alloys

    NASA Astrophysics Data System (ADS)

    Vora, Aditya M.

    2008-06-01

    The screening dependence theoretical investigations of the superconducting state parameters (SSP) viz. electron-phonon coupling strength λ, Coulomb pseudopotential μ∗, transition temperature TC , isotope effect exponent α and effective interaction strength NOV of five Mg 0.70Zn 0.30-xGa x ( x = 0.0, 0.06, 0.10, 0.15 and 0.20) ternary amorphous alloys viz. Mg 0.70Zn 0.30Ga 0.00, Mg 0.70Zn 0.24Ga 0.06, Mg 0.70Zn 0.20Ga 0.10, Mg 0.70Zn 0.15Ga 0.15 and Mg 0.70Zn 0.10Ga 0.20 have been reported for the first time using Ashcroft’s empty core (EMC) model potential. Five local field correction functions proposed by Hartree (H), Taylor (T), Ichimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) are used in the present investigation to study the screening influence on the aforesaid properties. It is observed that the electron-phonon coupling strength λ and the transition temperature TC are quite sensitive to the selection of the local field correction functions, whereas the Coulomb pseudopotential μ∗, isotope effect exponent α and effective interaction strength NOV show weak dependences on the local field correction functions. The transition temperature TC obtained from H-local field correction function is found in an excellent agreement with available experimental data. Quadratic TC equation has been proposed, which provide successfully the TC values of ternary amorphous alloys under consideration. Also, the present results are found in qualitative agreement with other such earlier reported data, which confirms the superconducting phase in the ternary amorphous alloys.

  2. Stress corrosion evaluation of HP 9Ni-4Co-0. 30C steel plate welds

    SciTech Connect

    Torres, P.D.

    1993-05-01

    A stress corrosion cracking (SCC) investigation was conducted on HP 9Ni-4Co-0.30C steel plate welds (welded by using straight polarity plasma arc and HP 9Ni-4Co-0.20C weld wire) since this material is being considered for use in the Advanced Solid Rocket Motor (ASRM) program. Prior to the welding, the material was double tempered at 538 C (1,000 F). After welding, only part of the material was stress relieved at 510 C (950 F) for 3 h. Round tensile specimens obtained from nonstress-relieved material were tested in 100-percent relative humidity at 38 C (100 F), in 3.5-percent NaCl alternate immersion, and in 5-percent salt spray at 35 C (95 F). Specimens obtained from stress-relieved material were tested in alternate immersion. The stress levels were 50, 75, and 90 percent of the corresponding 0.2-percent yield strength (YS). All the nonstress-relieved specimens exposed to salt spray and alternate immersion failed. Stress-relieved specimens (exposed to alternate immersion) failed at 75 and 90 percent of YS. No failures occurred at 50 percent of YS in the stress-relieved specimens which indicates a beneficial effect of the stress relief on the SCC resistance of these welds. The stress relief also had a positive effect on the mechanical properties of the welds (the most important being an increase of 21 percent on the YS). Under the conditions of these tests, the straight polarity plasma arc welded HP 9Ni4Co-0.30C steel plate was found highly susceptible to SCC in the nonstress-relieved condition. This susceptibility to SCC was reduced by stress relieving.

  3. Stress corrosion evaluation of HP 9Ni-4Co-0.30C steel plate welds

    NASA Technical Reports Server (NTRS)

    Torres, Pablo D.

    1993-01-01

    A stress corrosion cracking (SCC) investigation was conducted on HP 9Ni-4Co-0.30C steel plate welds (welded by using straight polarity plasma arc and HP 9Ni-4Co-0.20C weld wire) since this material is being considered for use in the Advanced Solid Rocket Motor (ASRM) program. Prior to the welding, the material was double tempered at 538 C (1,000 F). After welding, only part of the material was stress relieved at 510 C (950 F) for 3 h. Round tensile specimens obtained from nonstress-relieved material were tested in 100-percent relative humidity at 38 C (100 F), in 3.5-percent NaCl alternate immersion, and in 5-percent salt spray at 35 C (95 F). Specimens obtained from stress-relieved material were tested in alternate immersion. The stress levels were 50, 75, and 90 percent of the corresponding 0.2-percent yield strength (YS). All the nonstress-relieved specimens exposed to salt spray and alternate immersion failed. Stress-relieved specimens (exposed to alternate immersion) failed at 75 and 90 percent of YS. No failures occurred at 50 percent of YS in the stress-relieved specimens which indicates a beneficial effect of the stress relief on the SCC resistance of these welds. The stress relief also had a positive effect on the mechanical properties of the welds (the most important being an increase of 21 percent on the YS). Under the conditions of these tests, the straight polarity plasma are welded HP 9Ni4Co-0.30C steel plate was found highly susceptible to SCC in the nonstress-relieved condition. This susceptibility to SCC was reduced by stress relieving.

  4. 21-cm Intensity Mapping

    NASA Astrophysics Data System (ADS)

    Chang, Tzu-Ching; GBT-HIM Team

    2016-01-01

    The redshifted 21-cm emission from neutral hydrogen has emerged as a powerful probe for large-scale structure; a significant fraction of the observable universe can be mapped in the Intensity Mapping regime out to high redshifts. At redshifts around unity, the 21-cm emission traces the matter distribution and can be used to measure the Baryon Acoustic Oscillation (BAO) signature and constrain dark energy properties. I will describe our HI Intensity Mapping program at the Green Bank Telescope (GBT), aiming at measuring the 21cm power spectrum at z=0.8. A 800-MHz multi-beam focal-plane array for the GBT is currently under construction in order to facilitate a large-scale survey for BAO and the redshift-space distortion measurements for cosmological constraints.

  5. Halogens in CM Chondrites

    NASA Astrophysics Data System (ADS)

    Menard, J. M.; Caron, B.; Jambon, A.; Michel, A.; Villemant, B.

    2013-09-01

    We set up an extraction line of halogens (fluorine, chlorine) by pyrohydrolysis with 50 mg of rock. We analyzed 7 CM2 chondrites found in Antarctica and found that the Cl content of meteorites with an intact fusion crust is higher than those without.

  6. Magnetization reversal phenomena in (Cr0.70Ti0.30)5S6

    NASA Astrophysics Data System (ADS)

    Hashimoto, Satoshi; Matsuda, Yuji; Sato, Tetsuya; Anzai, Shuichiro

    2005-12-01

    Magnetization reversal phenomena (MRP) along magnetic order-order transitions have recently been reported on impurity-doped magnetic systems. Because imperfect long-range magnetic order exists in these systems, it is expected that a systematic investigation of MRP will give physical information on thermomagnetic processes of magnetic systems in the range from the micro- to nanoscales. As a typical order-order transition (a state doubly modulated by helical and canting orders to a collinear ferrimagnetic state) has been known to occur on Cr5S6 at a transition temperature Tt, we investigate the magnetizations of (Cr0.70Ti0.30)5S6 on heating and cooling runs in various magnetic fields. At 20Oe, the field-cooled magnetization just below the Curie temperature has a positive sign; the sign turns negative below the compensation temperature TCM (first step) and finally returns to positive below Tt (second step). The first-step MRP observed in this system is explained by the potential barriers resulting from anisotropy energy when the preferred direction of collinear ferrimagnetic moment reverses. The proposed mechanism for second-step MRP is the pinning effect caused by the impurity atoms (Ti) in the helical long-range-order chains. Comparing other examples of MRPs, we discuss the roles of local impurity centers in the thermomagnetic process in magnetic order-order transitions.

  7. [Spatial distribution patterns of soil organic carbon under Elacagnus angustifolia--Achnatherum splendens community in an arid area of Northwest China].

    PubMed

    Chi, Ting; Xu, Chi; Liu, Mao-Song; Zhang, Ming-Juan; Yang, Xue-Jiao

    2013-10-01

    An investigation was conducted to study the relationships of soil organic carbon (SOC) content with root biomass and soil moisture content as well as the accumulation mechanisms of SOC under the Elacagnus angustifolia-Achnatherum splenden community in Ningxia Hui Autonomous Region of Northwest China. The results showed that the SOC content decreased gradually with increasing soil depth, and changed gently in both horizontal and vertical directions. The correlations of the SOC content and its affecting factors varied with soil depth. In 0-30 cm layer, the SOC content was significantly negatively correlated with soil moisture content; in 60-150 cm layer, the SOC content was significantly positively correlated with soil moisture content and root biomass. Partial regression analysis indicated that the root biomass density in 0-30 cm soil layer contributed significantly to the variance of SOC content. In 60-150 cm layer, the SOC content was mainly affected by root system and soil moisture content; in 30-60 cm layer, no significant correlations were observed between the SOC content and the root biomass and soil moisture content. There was an obvious difference in the accumulation mechanism of SOC in different soil layers and at different locations of E. angustifolia--A. splendens community. PMID:24483063

  8. Ferroelectric and photovoltaic properties of transition metal doped Pb(Zr0.14Ti0.56Ni0.30)O3-δ thin films

    NASA Astrophysics Data System (ADS)

    Kumari, Shalini; Ortega, Nora; Kumar, Ashok; Scott, J. F.; Katiyar, R. S.

    2014-03-01

    We report nearly single phase Pb(Zr0.14Ti0.56Ni0.30)O3-δ (PZTNi30) ferroelectric having large remanent polarization (15-30 μC/cm2), 0.3-0.4 V open circuit voltage (VOC), reduced band gap (direct 3.4 eV, and indirect 2.9 eV), large ON and OFF photo current ratio, and the fast decay time. Reasonably good photo current density (1-5 μA/cm2) was obtained without gate bias voltage which significantly increased with large bias field. Ferroelectric polarization dictates the polarity of VOC and direction of short circuit current (ISC), a step forward towards the realization of noncentrosymmetric ferroelectric material sensitive to visible light.

  9. Ultrasonic properties near 50 K of the quasi-one-dimensional conductors A(0.30)MoO(3) (A = K, Rb) and Rb(0.30)(Mo(1-x)V(x))O(3).

    PubMed

    Saint-Paul, M; Dumas, J; Marcus, J

    2009-05-27

    The charge density wave (CDW) nonlinear conductivity of the blue bronzes A(0.30)MoO(3) (A = K, Rb) shows two different regimes depending on the temperature: a strongly damped CDW motion above ∼50 K and a CDW motion with almost no damping below ∼50 K. In a search for an elastic signature of this CDW behaviour, we performed ultrasonic measurements on A(0.30)MoO(3) single crystals in the temperature range 4-300 K. In Rb(0.30)MoO(3), at T∼50 K, upon cooling, a large increase of the sound velocity for the longitudinal mode measured along the [Formula: see text], [102] and b directions is observed. The ultrasonic attenuation coefficient shows an increase down to 50 K followed by a plateau. Similar results are found in K(0.30)MoO(3). In V-doped samples, Rb(0.30)(Mo(1-x)V(x))O(3) (x = 0.4%) the anomaly broadens and is shifted towards higher temperatures. The results are discussed in relation to the changes in the CDW rigidity, disorder and dielectric response. A scenario based on a glass transition for the CDW superstructure is proposed. PMID:21825552

  10. The Unified North American Soil Map and Its Implication on the Soil Organic Carbon Stock in North America

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wei, Y.; Post, W. M.; Cook, R. B.; Schaefer, K. M.

    2012-12-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for biospheric modeling. The UNASM combines state-of-the-art U.S. STATSGO and Soil Landscape of Canada (SLCs) databases, and for areas not covered by these datasets is filled with the Harmonized World Soil Database (HWSD). The UNASM contains seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0-30 cm) and the sub soil layer (30-100 cm) respectively, with the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon mass between the UNASM and HWSD, but the UNASM overall provides more detailed and higher-confidence information particularly in Alaska and central Canada. The estimate of the total soil organic carbon mass in the upper 100 cm soil profile based on the UNASM is 328.21Pg, of which 63.4% is from forest and 22.8% is from shrubland and grassland. This UNASM will help to provide more reliable estimates for the effects of global climate change and land use management on the terrestrial carbon cycle.

  11. A new impulsive seismic shear wave source for near-surface (0-30 m) seismic studies

    NASA Astrophysics Data System (ADS)

    Crane, J. M.; Lorenzo, J. M.

    2010-12-01

    Estimates of elastic moduli and fluid content in shallow (0-30 m) natural soils below artificial flood containment structures can be particularly useful in levee monitoring as well as seismic hazard studies. Shear wave moduli may be estimated from horizontally polarized, shear wave experiments. However, long profiles (>10 km) with dense receiver and shot spacings (<1m) cannot be collected efficiently using currently available shear wave sources. We develop a new, inexpensive, shear wave source for collecting fast, shot gathers over large acquisition sites. In particular, gas-charged, organic-rich sediments comprising most lower-delta sedimentary facies, greatly attenuate compressional body-waves. On the other hand, SH waves are relatively insensitive to pore-fluid moduli and can improve resolution. We develop a recoil device (Jolly, 1956) into a single-user, light-weight (<20 kg), impulsive, ground-surface-coupled SH wave generator, which is capable of working at rates of several hundred shotpoints per day. Older impulsive methods rely on hammer blows to ground-planted stationary targets. Our source is coupled to the ground with steel spikes and the powder charge can be detonated mechanically or electronically. Electrical fuses show repeatability in start times of < 50 microseconds. The barrel and shell-holder exceed required thicknesses to ensure complete safety during use. The breach confines a black-powder, 12-gauge shotgun shell, loaded with inert, environmentally safe ballast. In urban settings, produced heat and sound are confined by a detached, exterior cover. A moderate 2.5 g black-powder charge generates seismic amplitudes equivalent to three 4-kg sledge-hammer blows. We test this device to elucidate near subsurface sediment properties at former levee breach sites in New Orleans, Louisiana, USA. Our radio-telemetric seismic acquisition system uses an in-house landstreamer, consisting of 14-Hz horizontal component geophones, coupled to steel plates

  12. Metal and nanoparticle occurrence in biosolid-amended soils.

    PubMed

    Yang, Yu; Wang, Yifei; Westerhoff, Paul; Hristovski, Kiril; Jin, Virginia L; Johnson, Mari-Vaughn V; Arnold, Jeffrey G

    2014-07-01

    Metals can accumulate in soils amended with biosolids in which metals have been concentrated during wastewater treatment. The goal of this study is to inspect agricultural sites with long-term biosolid application for a suite of regulated and unregulated metals, including some potentially present as commonly used engineered nanomaterials (ENMs). Sampling occurred in fields at a municipal and a privately operated biosolid recycling facilities in Texas. Depth profiles of various metals were developed for control soils without biosolid amendment and soils with different rates of biosolid application (6.6 to 74 dry tons per hectare per year) over 5 to 25 years. Regulated metals of known toxicity, including chromium, copper, cadmium, lead, and zinc, had higher concentrations in the upper layer of biosolid-amended soils (top 0-30 cm or 0-15 cm) than in control soils. The depth profiles of unregulated metals (antimony, hafnium, molybdenum, niobium, gold, silver, tantalum, tin, tungsten, and zirconium) indicate higher concentrations in the 0-30 cm soil increment than in the 70-100 cm soil increment, indicating low vertical mobility after entering the soils. Titanium-containing particles between 50 nm and 250 nm in diameter were identified in soil by transmission electron microscopy (TEM) coupled with energy dispersive x-ray spectroscopy (EDX) analysis. In conjunction with other studies, this research shows the potential for nanomaterials used in society that enter the sewer system to be removed at municipal biological wastewater treatment plants and accumulate in agricultural fields. The metal concentrations observed herein could be used as representative exposure levels for eco-toxicological studies in these soils. PMID:24742554

  13. Mineland reclamation and soil organic carbon sequestration in Ohio

    SciTech Connect

    Akala, V.A.; Lal, R.

    1999-07-01

    The mining industry has been continuously involved in initiatives to reduce the emission of green house gases in to atmosphere. Control measures have been introduced in all steps starting from the mining of coal to energy production. Reclamation of mined land was and is one of the eco-friendly measures adopted by the industry. Apart from the inherent benefits of reclamation to improve on and offsite environmental quality, its potential to produce biomass and enhance soil organic carbon (SOC) has not been addressed. Reclamative effects of establishing forest and pasture with (graded) and without topsoil (ungraded) application on soil quality and soil carbon sequestration was studied on mine land in Ohio. The SOC pool for 0--30 cm depth for the undisturbed control sites was 56.6 MgC/ha for forest and 66.3 MgC/ha for pasture. In comparison, the SOC pool in the forest and pasture of graded mineland for 0--30 cm depth after 25 years of reclamation was 58.9 MgC/ha and 62.7 MgC/ha respectively. In ungraded mineland, the SOC pool in the 0--30 cm depth after 30 years of reclamation was 51.5 MgC/ha in forest and 58.9 MgC/ha in the pasture.

  14. Decision support tool for soil sampling of heterogeneous pesticide (chlordecone) pollution.

    PubMed

    Clostre, Florence; Lesueur-Jannoyer, Magalie; Achard, Raphaël; Letourmy, Philippe; Cabidoche, Yves-Marie; Cattan, Philippe

    2014-02-01

    When field pollution is heterogeneous due to localized pesticide application, as is the case of chlordecone (CLD), the mean level of pollution is difficult to assess. Our objective was to design a decision support tool to optimize soil sampling. We analyzed the CLD heterogeneity of soil content at 0-30- and 30-60-cm depth. This was done within and between nine plots (0.4 to 1.8 ha) on andosol and ferralsol. We determined that 20 pooled subsamples per plot were a satisfactory compromise with respect to both cost and accuracy. Globally, CLD content was greater for andosols and the upper soil horizon (0-30 cm). Soil organic carbon cannot account for CLD intra-field variability. Cropping systems and tillage practices influence the CLD content and distribution; that is CLD pollution was higher under intensive banana cropping systems and, while upper soil horizon was more polluted than the lower one with shallow tillage (<40 cm), deeper tillage led to a homogenization and a dilution of the pollution in the soil profile. The decision tool we proposed compiles and organizes these results to better assess CLD soil pollution in terms of sampling depth, distance, and unit at field scale. It accounts for sampling objectives, farming practices (cropping system, tillage), type of soil, and topographical characteristics (slope) to design a relevant sampling plan. This decision support tool is also adaptable to other types of heterogeneous agricultural pollution at field level. PMID:24014224

  15. Use of flue gas desulfurization gypsum for leaching Cd and Pb in reclaimed tidal flat soil.

    PubMed

    Yang, Ping; Li, Xian; Tong, Ze-Jun; Li, Qu-Sheng; He, Bao-Yan; Wang, Li-Li; Guo, Shi-Hong; Xu, Zhi-Min

    2016-04-01

    A soil column leaching experiment was conducted to eliminate heavy metals from reclaimed tidal flat soil. Flue gas desulfurization (FGD) gypsum was used for leaching. The highest removal rates of Cd and Pb in the upper soil layers (0-30 cm) were 52.7 and 30.5 %, respectively. Most of the exchangeable and carbonate-bound Cd and Pb were removed. The optimum FGD gypsum application rate was 7.05 kg·m(-2), and the optimum leaching water amount for the application was 217.74 L·m(-2). The application of FGD gypsum (two times) and the extension of the leaching interval time to 20 days increased the heavy metal removal rate in the upper soil layers. The heavy metals desorbed from the upper soil layers were re-adsorbed and fixed in the 30-70 cm soil layers. PMID:26758303

  16. Changes in soil carbon, nitrogen, and phosphorus due to land-use changes in Brazil

    NASA Astrophysics Data System (ADS)

    Groppo, J. D.; Lins, S. R. M.; Camargo, P. B.; Assad, E. D.; Pinto, H. S.; Martins, S. C.; Salgado, P. R.; Evangelista, B.; Vasconcellos, E.; Sano, E. E.; Pavão, E.; Luna, R.; Martinelli, L. A.

    2015-08-01

    In this paper, soil carbon, nitrogen and phosphorus concentrations and stocks were investigated in agricultural and natural areas in 17 plot-level paired sites and in a regional survey encompassing more than 100 pasture soils In the paired sites, elemental soil concentrations and stocks were determined in native vegetation (forests and savannas), pastures and crop-livestock systems (CPSs). Nutrient stocks were calculated for the soil depth intervals 0-10, 0-30, and 0-60 cm for the paired sites and 0-10, and 0-30 cm for the pasture regional survey by sum stocks obtained in each sampling intervals (0-5, 5-10, 10-20, 20-30, 30-40, 40-60 cm). Overall, there were significant differences in soil element concentrations and ratios between different land uses, especially in the surface soil layers. Carbon and nitrogen contents were lower, while phosphorus contents were higher in the pasture and CPS soils than in native vegetation soils. Additionally, soil stoichiometry has changed with changes in land use. The soil C : N ratio was lower in the native vegetation than in the pasture and CPS soils, and the carbon and nitrogen to available phosphorus ratio (PME) decreased from the native vegetation to the pasture to the CPS soils. In the plot-level paired sites, the soil nitrogen stocks were lower in all depth intervals in pasture and in the CPS soils when compared with the native vegetation soils. On the other hand, the soil phosphorus stocks were higher in all depth intervals in agricultural soils when compared with the native vegetation soils. For the regional pasture survey, soil nitrogen and phosphorus stocks were lower in all soil intervals in pasture soils than in native vegetation soils. The nitrogen loss with cultivation observed here is in line with other studies and it seems to be a combination of decreasing organic matter inputs, in cases where crops replaced native forests, with an increase in soil organic matter decomposition that leads to a decrease in the long

  17. On-farm assessment of tillage impact on the vertical distribution of soil organic carbon and structural soil properties in a semiarid region in Tunisia.

    PubMed

    Jemai, Imene; Ben Aissa, Nadhira; Ben Guirat, Saida; Ben-Hammouda, Moncef; Gallali, Tahar

    2012-12-30

    In semiarid areas, low and erratic rainfall, together with the intensive agricultural use of soils, has depleted soil organic carbon and degraded the soil's chemical, biological and physical fertility. To develop efficient soil-management practices for the rapid restoration of severely degraded soils, no-till, mulch-based cropping systems have been adopted. Thus, a study was conducted on a farm to evaluate the effect of a no-tillage system (NT) versus conventional tillage (CT) on the vertical (0-50 cm) distribution of soil organic carbon (SOC), bulk density (BD), total porosity (TP), structural instability (SI), stable aggregates and infiltration coefficient (Ks) in a clay loam soil under rain-fed conditions in a semiarid region of north-western Tunisia. CT consisting of moldboard plowing to a depth of 20 cm was used for continuous wheat production. NT by direct drilling under residue was used for 3 (NT3) and 7 (NT7) years in wheat/fava bean and wheat/sulla crop rotations, respectively. SOC was more significantly increased (p < 0.05) by NT3 and NT7 than by CT at respective depths of 0-10 and 0-20 cm, but a greater increase in the uppermost 10 cm of soil was observed in the NT7 field. NT3 management decreased BD and consequently increased TP at a depth of 0-10 cm. The same trend was observed for the NT7 treatment at a depth of 0-30 cm. Ks was not affected by the NT3 treatment but was improved at a depth of 0-30 cm by the NT7 treatment. Changes in BD, TP and Ks in the NT7 plot were significant only in the first 10 cm of the soil. Both NT3 and NT7 considerably reduced SI (p < 0.1) and enhanced stable aggregates (p < 0.05) across the soil profile. These differences were most pronounced under NT7 at a depth of 0-10 cm. The stratification ratio (SR) of the selected soil properties, except that of SI, showed significant differences between the CT and NT trials, indicating an improvement in soil quality. NT management in the farming systems of north-western Tunisia was

  18. THE METALLICITY OF THE CM DRACONIS SYSTEM

    SciTech Connect

    Terrien, Ryan C.; Fleming, Scott W.; Mahadevan, Suvrath; Deshpande, Rohit; Bender, Chad F.; Ramsey, Lawrence W.; Feiden, Gregory A.

    2012-11-20

    The CM Draconis system comprises two eclipsing mid-M dwarfs of nearly equal mass in a 1.27 day orbit. This well-studied eclipsing binary has often been used for benchmark tests of stellar models, since its components are among the lowest mass stars with well-measured masses and radii ({approx}< 1% relative precision). However, as with many other low-mass stars, non-magnetic models have been unable to match the observed radii and effective temperatures for CM Dra at the 5%-10% level. To date, the uncertain metallicity of the system has complicated comparison of theoretical isochrones with observations. In this Letter, we use data from the SpeX instrument on the NASA Infrared Telescope Facility to measure the metallicity of the system during primary and secondary eclipses, as well as out of eclipse, based on an empirical metallicity calibration in the H and K near-infrared (NIR) bands. We derive an [Fe/H] = -0.30 {+-} 0.12 that is consistent across all orbital phases. The determination of [Fe/H] for this system constrains a key dimension of parameter space when attempting to reconcile model isochrone predictions and observations.

  19. The Unified North American Soil Map and its implication on the soil organic carbon stock in North America

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wei, Y.; Post, W. M.; Cook, R. B.; Schaefer, K.; Thornton, M. M.

    2012-10-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled with the Harmonized World Soil Database version 1.1 (HWSD1.1). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0-30 cm) and the sub soil layer (30-100 cm) respectively, of the spatial resolution of 0.25° in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and Central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 347.70 Pg, of which 24.7% is under trees, 14.2% is under shrubs, and 1.3% is under grasses and 3.8% under crops. This UNASM data will provide a resource for use in land surface and terrestrial biogeochemistry modeling both for input of soil characteristics and for benchmarking model output.

  20. The Unified North American Soil Map and Its Implication on the Soil Organic Carbon Stock in North America

    SciTech Connect

    Liu, Shishi; Wei, Yaxing; Post, Wilfred M; Cook, Robert B; Schaefer, Kevin; Thornton, Michele M

    2013-01-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art U.S. STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled with the Harmonized World Soil Database version 1.1 (HWSD1.1). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the top soil layer (0-30 cm) and the sub soil layer (30-100 cm) respectively, of the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 347.70 Pg, of which 24.7% is under trees, 14.2% is under shrubs, and 1.3% is under grasses and 3.8% under crops. This UNASM data will provide a resource for use in land surface and terrestrial biogeochemistry modeling both for input of soil characteristics and for benchmarking model output.

  1. A global analysis of soil microbial biomass carbon, nitrogen and phosphorus in terrestrial ecosystems

    SciTech Connect

    Xu, Xiaofeng; Thornton, Peter E; Post, Wilfred M

    2013-01-01

    Soil microbes play a pivotal role in regulating land-atmosphere interactions; the soil microbial biomass carbon (C), nitrogen (N), phosphorus (P) and C:N:P stoichiometry are important regulators for soil biogeochemical processes; however, the current knowledge on magnitude, stoichiometry, storage, and spatial distribution of global soil microbial biomass C, N, and P is limited. In this study, 3087 pairs of data points were retrieved from 281 published papers and further used to summarize the magnitudes and stoichiometries of C, N, and P in soils and soil microbial biomass at global- and biome-levels. Finally, global stock and spatial distribution of microbial biomass C and N in 0-30 cm and 0-100 cm soil profiles were estimated. The results show that C, N, and P in soils and soil microbial biomass vary substantially across biomes; the fractions of soil nutrient C, N, and P in soil microbial biomass are 1.6% in a 95% confidence interval of (1.5%-1.6%), 2.9% in a 95% confidence interval of (2.8%-3.0%), and 4.4% in a 95% confidence interval of (3.9%-5.0%), respectively. The best estimates of C:N:P stoichiometries for soil nutrients and soil microbial biomass are 153:11:1, and 47:6:1, respectively, at global scale, and they vary in a wide range among biomes. Vertical distribution of soil microbial biomass follows the distribution of roots up to 1 m depth. The global stock of soil microbial biomass C and N were estimated to be 15.2 Pg C and 2.3 Pg N in the 0-30 cm soil profiles, and 21.2 Pg C and 3.2 Pg N in the 0-100 cm soil profiles. We did not estimate P in soil microbial biomass due to data shortage and insignificant correlation with soil total P and climate variables. The spatial patterns of soil microbial biomass C and N were consistent with those of soil organic C and total N, i.e. high density in northern high latitude, and low density in low latitudes and southern hemisphere.

  2. The Murrumbidgee soil moisture monitoring network data set

    NASA Astrophysics Data System (ADS)

    Smith, A. B.; Walker, J. P.; Western, A. W.; Young, R. I.; Ellett, K. M.; Pipunic, R. C.; Grayson, R. B.; Siriwardena, L.; Chiew, F. H. S.; Richter, H.

    2012-07-01

    This paper describes a soil moisture data set from the 82,000 km2 Murrumbidgee River Catchment in southern New South Wales, Australia. Data have been archived from the Murrumbidgee Soil Moisture Monitoring Network (MSMMN) since its inception in September 2001. The Murrumbidgee Catchment represents a range of conditions typical of much of temperate Australia, with climate ranging from semiarid to humid and land use including dry land and irrigated agriculture, remnant native vegetation, and urban areas. There are a total of 38 soil moisture-monitoring sites across the Murrumbidgee Catchment, with a concentration of sites in three subareas. The data set is composed of 0-5 (or 0-8), 0-30, 30-60, and 60-90 cm average soil moisture, soil temperature, precipitation, and other land surface model forcing at all sites, together with other ancillary data. These data are available on the World Wide Web at http://www.oznet.org.au.

  3. Long-term persistence of various 14C-labeled pesticides in soils.

    PubMed

    Jablonowski, Nicolai D; Linden, Andreas; Köppchen, Stephan; Thiele, Björn; Hofmann, Diana; Mittelstaedt, Werner; Pütz, Thomas; Burauel, Peter

    2012-09-01

    The fate of the 14C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9-17 years) in field based lysimeters subject to crop rotation. Analysis of residual 14C activity in the soils revealed 19% (ETD soil; 0-10 cm depth), 35% (MBT soil; 0-30), and 43% (ANI soil; 0-30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide 14C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials. PMID:22591787

  4. Estimation of soil parameters over bare agriculture areas from C-band polarimetric SAR data using neural networks

    NASA Astrophysics Data System (ADS)

    Baghdadi, N.; Cresson, R.; El Hajj, M.; Ludwig, R.; La Jeunesse, I.

    2012-06-01

    The purpose of this study was to develop an approach to estimate soil surface parameters from C-band polarimetric SAR data in the case of bare agricultural soils. An inversion technique based on multi-layer perceptron (MLP) neural networks was introduced. The neural networks were trained and validated on a noisy simulated dataset generated from the Integral Equation Model (IEM) on a wide range of surface roughness and soil moisture, as it is encountered in agricultural contexts for bare soils. The performances of neural networks in retrieving soil moisture and surface roughness were tested for several inversion cases using or not using a-priori knowledge on soil parameters. The inversion approach was then validated using RADARSAT-2 images in polarimetric mode. The introduction of expert knowledge on the soil moisture (dry to wet soils or very wet soils) improves the soil moisture estimates, whereas the precision on the surface roughness estimation remains unchanged. Moreover, the use of polarimetric parameters α1 and anisotropy were used to improve the soil parameters estimates. These parameters provide to neural networks the probable ranges of soil moisture (lower or higher than 0.30 cm3 cm-3) and surface roughness (root mean square surface height lower or higher than 1.0 cm). Soil moisture can be retrieved correctly from C-band SAR data by using the neural networks technique. Soil moisture errors were estimated at about 0.098 cm3 cm-3 without a-priori information on soil parameters and 0.065 cm3 cm-3 (RMSE) applying a-priori information on the soil moisture. The retrieval of surface roughness is possible only for low and medium values (lower than 2 cm). Results show that the precision on the soil roughness estimates was about 0.7 cm. For surface roughness lower than 2 cm, the precision on the soil roughness is better with an RMSE about 0.5 cm. The use of polarimetric parameters improves only slightly the soil parameters estimates.

  5. Measurement of soil moisture with cosmic-ray neutrons in deciduous forests

    NASA Astrophysics Data System (ADS)

    Heidbüchel, Ingo; Blume, Theresa; Güntner, Andreas

    2014-05-01

    In deciduous forests the calibration of cosmic-ray soil moisture sensors is difficult since the amount of water stored inside and on vegetation (leaves, branches, stems) varies seasonally. A one-time calibration conducted during summer can therefore introduce errors to the method that are especially pronounced in the winter season. We performed calibration in a deciduous forest at the TERENO observatory in north-eastern Germany at different times throughout the year to capture the changing influence of water in the vegetation on the calibration results. Additionally, we calibrated the cosmic-ray neutron sensor with soil samples from different soil depths (0-10 cm, 0-20 cm, 0-30 cm). We compared the resulting soil moisture time series with time series of FDR-based soil moisture point measurements at different depths. This allows us to estimate the error introduced by the influence of organic layers at the soil surface (litter, decomposed organic material) which can vary temporally. The same sensor setup was also used to look at time-lags between the cosmic-ray soil moisture signal and measurements of precipitation, intercepted water and soil moisture point measurements at different depths. Recorded time lags between point measurements and cosmic-ray soil moisture results can potentially help in tracking precipitation on its way through the canopy, the organic layer and into the soils.

  6. The Unified North American Soil Map and its implication on the soil organic carbon stock in North America

    NASA Astrophysics Data System (ADS)

    Liu, S.; Wei, Y.; Post, W. M.; Cook, R. B.; Schaefer, K.; Thornton, M. M.

    2013-05-01

    The Unified North American Soil Map (UNASM) was developed to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled by using the Harmonized World Soil Database version 1.21 (HWSD1.21). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the topsoil layer (0-30 cm) and the subsoil layer (30-100 cm), respectively, of the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 365.96 Pg, of which 23.1% is under trees, 14.1% is in shrubland, and 4.6% is in grassland and cropland. This UNASM data will provide a resource for use in terrestrial ecosystem modeling both for input of soil characteristics and for benchmarking model output.

  7. The Unified North American Soil Map and Its Implication on the Soil Organic Carbon Stock in North America

    NASA Astrophysics Data System (ADS)

    Wei, Y.; Liu, S.; Huntzinger, D. N.; Michalak, A. M.; Post, W. M.; Cook, R. B.; Schaefer, K. M.; Thornton, M.

    2014-12-01

    The Unified North American Soil Map (UNASM) was developed by Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) to provide more accurate regional soil information for terrestrial biosphere modeling. The UNASM combines information from state-of-the-art US STATSGO2 and Soil Landscape of Canada (SLCs) databases. The area not covered by these datasets is filled by using the Harmonized World Soil Database version 1.21 (HWSD1.21). The UNASM contains maximum soil depth derived from the data source as well as seven soil attributes (including sand, silt, and clay content, gravel content, organic carbon content, pH, and bulk density) for the topsoil layer (0-30 cm) and the subsoil layer (30-100 cm), respectively, of the spatial resolution of 0.25 degrees in latitude and longitude. There are pronounced differences in the spatial distributions of soil properties and soil organic carbon between UNASM and HWSD, but the UNASM overall provides more detailed and higher-quality information particularly in Alaska and central Canada. To provide more accurate and up-to-date estimate of soil organic carbon stock in North America, we incorporated Northern Circumpolar Soil Carbon Database (NCSCD) into the UNASM. The estimate of total soil organic carbon mass in the upper 100 cm soil profile based on the improved UNASM is 365.96 Pg, of which 23.1% is under trees, 14.1% is in shrubland, and 4.6% is in grassland and cropland. This UNASM data has been provided as a resource for use in terrestrial ecosystem modeling of MsTMIP both for input of soil characteristics and for benchmarking model output.

  8. Soil moisture depletion under simulated drought in the Amazon: impacts on deep root uptake.

    PubMed

    Markewitz, Daniel; Devine, Scott; Davidson, Eric A; Brando, Paulo; Nepstad, Daniel C

    2010-08-01

    *Deep root water uptake in tropical Amazonian forests has been a major discovery during the last 15 yr. However, the effects of extended droughts, which may increase with climate change, on deep soil moisture utilization remain uncertain. *The current study utilized a 1999-2005 record of volumetric water content (VWC) under a throughfall exclusion experiment to calibrate a one-dimensional model of the hydrologic system to estimate VWC, and to quantify the rate of root uptake through 11.5 m of soil. *Simulations with root uptake compensation had a relative root mean square error (RRMSE) of 11% at 0-40 cm and < 5% at 350-1150 cm. The simulated contribution of deep root uptake under the control was c. 20% of water demand from 250 to 550 cm and c. 10% from 550 to 1150 cm. Furthermore, in years 2 (2001) and 3 (2002) of throughfall exclusion, deep root uptake increased as soil moisture was available but then declined to near zero in deep layers in 2003 and 2004. *Deep root uptake was limited despite high VWC (i.e. > 0.30 cm(3) cm(-3)). This limitation may partly be attributable to high residual water contents (theta(r)) in these high-clay (70-90%) soils or due to high soil-to-root resistance. The ability of deep roots and soils to contribute increasing amounts of water with extended drought will be limited. PMID:20659251

  9. [Soil condensation water in different habitats in Horqin sandy land: an experimental study].

    PubMed

    Liu, Xin-Ping; He, Yu-Hui; Zhao, Xue-Yong; Li, Yu-Lin; Li, Yu-Qiang; Li, Yan-Qing; Li, Shi-min

    2009-08-01

    Weighing method was adopted to study the formation time and the amount of soil condensation water in four habitats (mobile sandy land, fixed sandy land, farmland, and Mongolian pine forest land) in Horqin Sandy Land in August 2007. The soil condensation water began to form at 20:00-22:00, increased gradually at 22:00-4:00, and began to evaporate after 4:00. In the four habitats, soil condensation water was mainly formed in 0-9 cm layer, and the amount was the greatest in 0-3 cm layer, accounting for 40% of the total. The soil condensation water also formed in 9-30 cm layer, but in very small amount. There was a greater difference in the mean daily amount of soil condensation water in 0-3 cm layer in the four habitats, with the sequence of fixed sandy land > mobile sandy land > farmland > Mongolian pine forest land, which indicated that the habitat with better vegetation condition was not benefit the formation of soil condensation water. The mean daily amount of soil condensation water in 0-30 cm layer was 0.172 mm in fixed sandy land, 0.128 mm in Mongolian pine forest land, 0.120 mm in mobile sandy land, and 0.110 mm in farmland. PMID:19947212

  10. Magnetic properties of (La0.56Ce0.14)Sr0.30MnO3 perovskite

    NASA Astrophysics Data System (ADS)

    Yahyaoui, Samia; Diep, H. T.

    2016-09-01

    We investigate in this paper magnetic properties of the perovskite compound (La0.56Ce0.14)Sr0.30MnO3. The method we use here is Monte Carlo simulation, in which we take into account different kinds of interactions between nearest and between next-nearest magnetic ions Mn3+ (S = 2), Mn4+ (S = 3 / 2) and Ce3+ (S = 1 / 2). Using a classical spin model, we have calculated the internal energy, the magnetization per ion type and their corresponding magnetic susceptibility, as well as the Edwards-Anderson order parameter for each ion kind. We also studied the applied-field effect on the system magnetization. Our results show a good agreement with experiments.

  11. Serpentine Nanotubes in CM Chondrites

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    The CM chondrites are primitive meteorites that formed during the early solar system. Although they retain much of their original physical character, their matrices and fine-grained rims (FGRs) sustained aqueous alteration early in their histories [1- 3]. Serpentine-group minerals are abundant products of such alteration, and information regarding their structures, compositions, and spatial relationships is important for determining the reactions that produced them and the conditions under which they formed. Our recent work on FGRs and matrices of the CM chondrites has revealed new information on the structures and compositions of serpentine-group minerals [4,5] and has provided insights into the evolution of these primitive meteorites. Here we report on serpentine nanotubes from the Mighei and Murchison CM chondrites [6].

  12. Measurements of soil and canopy exchange rates in the Amazon rain forest using 222Rn

    NASA Astrophysics Data System (ADS)

    Trumbore, S. E.; Keller, M.; Wofsy, S. C.; da Costa, J. M.

    1990-09-01

    Measurements of the emission of 222Rn from Amazon forest soils, and profiles of 222Rn in air were used to study the ventilation of the soil atmosphere and the nocturnal forest canopy. The emission of 222Rn from the yellow clay soils dominant in the study area averaged 0.38±0.07 atom cm-2 s-1. Nearby sand soils had similar fluxes, averaging 0.30 ± 0.07 atom cm-2 s-1. The effective diffusivity in the clay soil (0.008±0.004 cm2 s-1), was lower than that for the sand soil (0.033±0.030 cm2 s-1). Profiles of 222Rn and CO2 in air showed steepest concentration gradients in the layer between 0 and 3 m above the soil surface. Aerodynamic resistances calculated for this layer from 222Rn and CO2 varied from 1.6 to 18 s cm-1, with greater resistance during the afternoon than at night. Time averaged profiles of 222Rn in the forest canopy measured during the evening and night were combined with the soil flux measurements to compute the resistance of the subcanopy to exchange with overlying air. The integrated nocturnal rate of gas exchange between the canopy layer (0 to 41 m) and overlying atmosphere based on 222Rn averaged 0.33±0.15 cm s-1. An independent estimate of gas exchange, based on 13 nights of CO2 profiles, averaged 0.21±0.40 cm s-1. These exchange rates correspond to flushing times for the 41 m canopy layer of 3.4 and 5.5 hours, respectively. Comparison of 222Rn and CO2 profiles show that the nocturnal production of CO2 by above-ground vegetation was about 20% of the soil emission source, consistent with data from eddy-correlation experiments (Fan et al., this issue).

  13. 344 cm x 86 cm low mass vacuum window

    SciTech Connect

    Reimers, R.M.; Porter, J.; Meneghetti, J.; Wilde, S.; Miller, R.

    1983-08-01

    The LBL Heavy Ion Spectrometer System (HISS) superconducting magnet contains a 1 m x 3.45 m x 2 m vacuum tank in its gap. A full aperture thin window was needed to minimize background as the products of nuclear collisions move from upstream targets to downstream detectors. Six windows were built and tested in the development process. The final window's unsupported area is 3m/sup 2/ with a 25 cm inward deflection. The design consists of a .11 mm Nylon/aluminum/polypropylene laminate as a gas seal and .55 mm woven aramid fiber for strength. Total mass is 80 milligrams per cm/sup 2/. Development depended heavily on past experience and testing. Safety considerations are discussed.

  14. Changes in soil carbon, nitrogen and phosphorus due to land-use changes in Brazil

    NASA Astrophysics Data System (ADS)

    Groppo, J. D.; Lins, S. R. M.; Camargo, P. B.; Assad, E. D.; Pinto, H. S.; Martins, S. C.; Salgado, P. R.; Evangelista, B.; Vasconcellos, E.; Sano, E. E.; Pavão, E.; Luna, R.; Martinelli, L. A.

    2015-02-01

    In this paper soil carbon, nitrogen and phosphorus concentrations and related elemental ratios, as well as and nitrogen and phosphorus stocks were investigated in 17 paired sites and in a regional survey encompassing more than 100 pasture soils in the Cerrado, Atlantic Forest, and Pampa, the three important biomes of Brazil. In the paired sites, elemental soil concentrations and stocks were determined in native vegetation, pastures and crop-livestock systems (CPS). Overall, there were significant differences in soil element concentrations and ratios between different land uses, especially in the surface soil layers. Carbon and nitrogen contents were lower, while phosphorus contents were higher in the pasture and CPS soils than in forest soils. Additionally, soil stoichiometry has changed with changes in land use. The soil C : N ratio was lower in the forest than in the pasture and CPS soils; and the carbon and nitrogen to available phosphorus ratio (PME) decreased from the forest to the pasture to the CPS soils. The average native vegetation soil nitrogen stocks at 0-10, 0-30 and 0-60 cm soil depth layers were equal to approximately 2.3, 5.2, 7.3 Mg ha-1, respectively. In the paired sites, nitrogen loss in the CPS systems and pasture soils were similar and equal to 0.6, 1.3 and 1.5 Mg ha-1 at 0-10, 0-30 and 0-60 cm soil depths, respectively. In the regional pasture soil survey, nitrogen soil stocks at 0-10 and 0-30 soil layers were equal to 1.6 and 3.9 Mg ha-1, respectively, and lower than the stocks found in the native vegetation of paired sites. On the other hand, the soil phosphorus stocks were higher in the CPS and pasture of the paired sites than in the soil of the original vegetation. The original vegetation soil phosphorus stocks were equal to 11, 22, and 43 kg ha-1 in the three soil depths, respectively. The soil phosphorus stocks increased in the CPS systems to 30, 50, and 63 kg ha-1, respectively, and in the pasture pair sites to 22, 47, and 68 kg ha-1

  15. Computational study on the negative electron affinities of NO2 -.(H2O)n clusters (n=0-30).

    PubMed

    Ejsing, Anne Marie; Brøndsted Nielsen, Steen

    2007-04-21

    Here we report negative electron affinities of NO(2)(-).(H2O)n clusters (n=0-30) obtained from density functional theory calculations and a simple correction to Koopmans' theorem. The method relies on the calculation of the detachment energy of the monoanion and its highest occupied molecular orbital and lowest unoccupied molecular orbital energies, and explicit calculations on the dianion itself are avoided. A good agreement with resonances in the cross section for neutral production in electron scattering experiments is found for n=0, 1, and 2. We find several isomeric structures of NO(2)(-).(H2O)2 of similar energy that elucidate the interplay between water-water and ion-water interactions. The topology is predicted to influence the electron affinity by 0.5 and 0.4 eV for NO(2)(-).(H2O) and NO(2)(-).(H2O)2, respectively. The electron affinity of larger clusters is shown to follow a (n+delta)-1/3 dependence, where delta=3 represents the number of water molecules that in volume, could replace NO(2) (-). PMID:17461632

  16. Operating characteristics of a 7. 6 mm (0. 30 inch) diameter two-stage light-gas gun

    SciTech Connect

    Susoeff, A R; Hawke, R S; Bowen, P R; Greenwood, D W; Marshall, F R

    1992-07-01

    a series of tests was conducted to determine the operating requirements needed to obtain maximum projectile velocity within the engineering design limits of a two-stage light-gas gun with a 7.6 mm (0.30 inch) diameter bore launch tube. The tests were conducted in a medium vacuum flight range. Previous experience with the gun was used to establish the minimum requirements for optimum efficiency. Two operating parameters, propellant load and drive gas pressure, were varied in order to find an initial optimum operating condition at a conservative propellant load. Propellant load and driver gas pressure were then incrementally increased. This procedure was methodically applied until significant mechanical deformation of a critical gun component took place. This report presents the results of these tests. Projectile velocity was measured to better than 3 percent accuracy using a magnetic induction technique. A 0.485 gram polycarbonate projectile was launched to a velocity of 7.77 km/s during the tests. 13 refs.

  17. Austenite decomposition to carbide-rich products in Fe-0.30C-6.3W

    NASA Astrophysics Data System (ADS)

    Hackenberg, R. E.; Granada, D. G.; Shiflet, G. J.

    2002-12-01

    The kinetics, morphology, and elemental distributions associated with the decomposition of austenite in Fe-0.30C-6.3W were surveyed, especially in the bay region of the time-temperature-transformation (TTT) diagram. Carbide precipitation characteristics were of particular interest. Similar to Fe-C-Mo and Fe-C-Cr alloys, grain- and twin-boundary bainite containing sheets of alloy carbides dominated the microstructure at and above the bay, while popcorn-like bainite was observed immediately below the bay. Nonequilibrium carbide-phase combinations were obtained both above and below the bay, although W partitioning to the alloy carbides was always observed. The carbon level in the remaining austenite increased with reaction time at a given temperature, which, at the later stages of reaction, helped trigger the growth of a constituent containing a high density of nonlamellar carbides. These nonequilibrium reaction-path characteristics are considered to originate from crystallographic and interfacial structure constraints affecting the nucleation of carbides at ferrite-austenite interfaces.

  18. Long-term effect of agricultural reclamation on soil chemical properties of a coastal saline marsh in Bohai Rim, northern China.

    PubMed

    Wang, Yidong; Wang, Zhong-Liang; Feng, Xiaoping; Guo, Changcheng; Chen, Qing

    2014-01-01

    Over the past six decades, coastal wetlands in China have experienced rapid and extensive agricultural reclamation. In the context of saline conditions, long-term effect of cultivation after reclamation on soil chemical properties has not been well understood. We studied this issue using a case of approximately 60-years cultivation of a coastal saline marsh in Bohai Rim, northern China. The results showed that long-term reclamation significantly decreased soil organic carbon (SOC) (-42.2%) and total nitrogen (TN) (-25.8%) at surface layer (0-30 cm) as well as their stratification ratios (SRs) (0-5 cm:50-70 cm and 5-10 cm:50-70 cm). However, there was no significant change in total phosphorus (TP) as well as its SRs under cultivation. Cultivation markedly reduced ratios of SOC to TN, SOC to TP and TN to TP at surface layer (0-30 cm) and their SRs (0-5 cm:50-70 cm). After cultivation, electrical conductivity and salinity significantly decreased by 60.1% and 55.3% at 0-100 cm layer, respectively, suggesting a great desalinization. In contrast, soil pH at 20-70 cm horizons notably increased as an effect of reclamation. Cultivation also changed compositions of cations at 0-10 cm layer and anions at 5-100 cm layer, mainly decreasing the proportion of Na+, Cl- and SO4(2-). Furthermore, cultivation significantly reduced the sodium adsorption ratio and exchangeable sodium percentage in plow-layer (0-20 cm) but not residual sodium carbonate, suggesting a reduction in sodium harm. PMID:24695526

  19. Non-invasive Field Measurements of Soil Water Content Using a Pulsed 14 MeV Neutron Generator

    SciTech Connect

    Mitra S.; Wielopolski L.; Omonode, R.; Novak, J.; Frederick, J.; Chan, A.

    2012-01-26

    Current techniques of soil water content measurement are invasive and labor-intensive. Here, we demonstrate that an in situ soil carbon (C) analyzer with a multi-elemental analysis capability, developed for studies of terrestrial C sequestration, can be used concurrently to non-invasively measure the water content of large-volume ({approx}0.3 m{sup 3}) soil samples. Our objectives were to investigate the correlations of the hydrogen (H) and oxygen (O) signals with water to the changes in the soil water content in laboratory experiments, and in an agricultural field. Implementing prompt gamma neutron activation analyses we showed that in the field, the signal from the H nucleus better indicates the soil water content than does that from the O nucleus. Using a field calibration, we were able to use the H signal to estimate a minimum detectable change of {approx}2% volumetric water in a 0-30 cm depth of soil.

  20. AMR on the CM-2

    NASA Technical Reports Server (NTRS)

    Berger, Marsha J.; Saltzman, Jeff S.

    1992-01-01

    We describe the development of a structured adaptive mesh algorithm (AMR) for the Connection Machine-2 (CM-2). We develop a data layout scheme that preserves locality even for communication between fine and coarse grids. On 8K of a 32K machine we achieve performance slightly less than 1 CPU of the Cray Y-MP. We apply our algorithm to an inviscid compressible flow problem.

  1. Development of a national geodatabase (Greece) for soil surveys and land evaluation using space technology and GIS

    NASA Astrophysics Data System (ADS)

    Bilas, George; Dionysiou, Nina; Karapetsas, Nikolaos; Silleos, Nikolaos; Kosmas, Konstantinos; Misopollinos, Nikolaos

    2016-04-01

    This project was funded by OPEKEPE, Ministry of Agricultural Development and Food, Greece and involves development of a national geodatabase and a WebGIS that encompass soil data of all the agricultural areas of Greece in order to supply the country with a multi-purpose master plan for agricultural land management. The area mapped covered more than 385,000 ha divided in more than 9.000 Soil Mapping Units (SMUs) based on physiographic analysis, field work and photo interpretation of satellite images. The field work included description and sampling in three depths (0-30, 30-60 and >60 cm) of 2,000 soil profiles and 8,000 augers (sampling 0-30 and >30 cm). In total more than 22,000 soil samples were collected and analyzed for determining main soil properties associated with soil classification and soil evaluation. Additionally the project included (1) integration of all data in the Soil Geodatabase, (2) finalization of SMUs, (3) development of a Master Plan for Agricultural Land Management and (4) development and operational testing of the Web Portal for e-information and e-services. The integrated system is expected, after being fully operational, to provide important electronic services and benefits to farmers, private sector and governmental organizations. An e-book with the soil maps of Greece was also provided including 570 sheets with data description and legends. The Master Plan for Agricultural Land Management includes soil quality maps for 30 agricultural crops, together with maps showing soil degradation risks, such as erosion, desertification, salinity and nitrates, thus providing the tools for soil conservation and sustainable land management.

  2. Windthrows increase soil carbon stocks in a Central Amazon forest

    NASA Astrophysics Data System (ADS)

    dos Santos, L. T.; Magnabosco Marra, D.; Trumbore, S.; Camargo, P. B.; Chambers, J. Q.; Negrón-Juárez, R. I.; Lima, A. J. N.; Ribeiro, G. H. P. M.; dos Santos, J.; Higuchi, N.

    2015-12-01

    Windthrows change forest structure and species composition in Central Amazon forests. However, the effects of widespread tree mortality associated with wind-disturbances on soil properties have not yet been described. In this study, we investigated short-term effects (seven years after disturbance) of a windthrow event on soil carbon stocks and concentrations in a Central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 4.18 Mg ha-1, mean ± standard error) was marginally higher (p = 0.009) than that from undisturbed plots (47.7 ± 6.95 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.08 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.12 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r = 0.575 and p = 0.019) and with tree mortality intensity (r = 0.493 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. Higher nutrient availability in soils from large canopy gaps created by wind disturbance may increase vegetation resilience and favor forest recovery.

  3. Drivers of organic carbon stock of agricultural soils in eastern Australia

    NASA Astrophysics Data System (ADS)

    Rabbi, Sheikh M. F.; Tighe, Matthew; Delgado-Baquerizo, Manuel; Cowie, Annette; Robertson, Fiona; Dalal, Ram; Page, Kathryn; Crawford, Doug; Wilson, Brian; Schwenke, Graeme; Mcleod, Malem; Badgery, Warwick; Dang, Yash; Bell, Mike; Baldock, Jeff

    2015-04-01

    Assessing the factors that control carbon storage is the key to formulating conservation policies and sustainable soil management under changing environments. Here, we evaluate the major drivers of soil organic carbon storage in eastern Australia. To do this, we used a regional dataset including 1482 sites and targeting key land uses and soil management practices on major soils of New South Wales (NSW), Queensland (QLD) and Victoria (VIC). Structural equation modeling (SEM) and conditional inference tree (CTREE) analyses were performed to evaluate the relative importance of climate, topography, soil properties, land use and soil management practices on soil organic carbon stocks in 0-30 cm. The results showed that aridity, the most important factor controlling carbon storage, had a strong negative (r = -0.82, p<0.01), whereas clay content had a strong positive (r = 0.42, p<0.01) relationship with soil carbon stock. Only a small portion (<1%) of total variation in carbon stock could be explained by land use. The results of CTREE analysis showed that pastures, and pasture dominant crop-pasture rotations had positive influence on soil carbon stocks. The CTREE results also indicated that aridity regulates the amount of carbon present in the soil under different land uses. Using a novel multivariate technique the current work identified that aridity and clay content of soil are the main drivers of carbon storage at a regional scale over others factors such as land uses and soil management practices.

  4. Cesium-137 concentration of soils in Pest County, Hungary.

    PubMed

    Szabó, Katalin Zsuzsanna; Udvardi, Beatrix; Horváth, Akos; Bakacsi, Zsófia; Pásztor, László; Szabó, József; Laczkó, László; Szabó, Csaba

    2012-08-01

    This paper presents the results of measurements of (137)Cs in soils in Pest County, Hungary. We investigated forty five soil monoliths from monitoring locations of a countrywide Soil Information and Monitoring System (SIMS) at depths of 0-30, 30-60, 60-90, 90-120 and 120-150 cm. The (137)Cs concentrations were determined by gamma spectroscopy. We found that only the upper layer of soil (0-30 cm) contained (137)Cs above the detection limit (0.5 Bq kg(-1)). The (137)Cs concentration values ranged from the detection limit to 61.1 Bq kg(-1) ± 2.2 Bq kg(-1) and were lognormally distributed. The concentrations had a geometric mean 6.4 Bq kg(-1) and a geometric standard deviation 2.3 (an arithmetic mean 9.5 Bq kg(-1), an arithmetic standard deviation 11.3 Bq kg(-1)). We constructed a (137)Cs map for Pest County this is the first detailed (137)Cs map in Hungary. Concentrations were systematically higher (10.0-61.1 Bq kg(-1)) than average in the Pilis and Buda Mountains and the Northern part of the Gödöllő Hills. In contrast, low concentrations (0.0-10.0 Bq kg(-1)) characterized the southern part of the Gödöllő Hills, the Pest Plane and the Börzsöny Mountains. Two highest values were 46.9 Bq kg(-1) and 61.1 Bq kg(-1): one of these localities, a loamy brown forest soil was chosen to study relationship between (137)Cs migration and clay materials of the soil. According to differential thermal analysis (DTA) and x-ray diffraction (XRD) analyses, illite and kaolinite were dominant in the soil. The amount of clay was closely proportional to (137)Cs concentration (R = 0.89). At the locality having the highest surface concentration, 78% of the total detected (137)Cs concentration was measured in the top 3 cm layer of soil profile and there was no detectable concentration below 20 cm. This result indicates that penetration of (137)Cs into the soil is a very slow process in this case. Analysis of this depth profile showed lower (137)Cs migration

  5. A new electrical and mechanically detonatable shear wave source for near surface (0-30 m) seismic acquisition

    NASA Astrophysics Data System (ADS)

    Crane, J. M.; Lorenzo, J. M.; Harris, J. B.

    2013-04-01

    We present a new, impulsive, horizontal shear source capable of performing long shot profiles in a time-efficient and repeatable manner. The new shear source is ground-coupled by eight 1/2″ (1.27 cm) × 2″ (5.08 cm) steel spikes. Blank shotshells (12-gauge) used as energy sources can be either mechanically or electrically detonated. Electrical fuses have a start time repeatability of < 50 μs. This source can be operated by a single individual, and takes only ~ 10 s between shots as opposed to ~ 30 s for six stacked hammer blows. To ensure complete safety, the shotshell holder is surrounded by a protective 6″ (15.24 cm)-thick barrel, a push-and-twist-locked breach, and a safety pin. We conducted field tests at the 17th Street Canal levee breach site in New Orleans, Louisiana (30.017° N 90.121° W) and at an instrumented test borehole at Millsaps College in Jackson, Mississippi (32.325° N 93.182° W) to compare our new source and a traditional hammer impact source. The new shear source produces a broader-band of frequencies (30-100 Hz cf. 30-60 Hz). Signal generated by the new shear source has signal-to-noise ratios equivalent to ~ 3 stacked hammer blows to the hammer impact source. Ideal source signals must be broadband in frequency, have a high SNR, be consistent, and have precise start times; all traits of the new shear source.

  6. Estimating soil water-holding capacities by linking the Food and Agriculture Organization Soil map of the world with global pedon databases and continuous pedotransfer functions

    NASA Astrophysics Data System (ADS)

    Reynolds, C. A.; Jackson, T. J.; Rawls, W. J.

    2000-12-01

    Spatial soil water-holding capacities were estimated for the Food and Agriculture Organization (FAO) digital Soil Map of the World (SMW) by employing continuous pedotransfer functions (PTF) within global pedon databases and linking these results to the SMW. The procedure first estimated representative soil properties for the FAO soil units by statistical analyses and taxotransfer depth algorithms [Food and Agriculture Organization (FAO), 1996]. The representative soil properties estimated for two layers of depths (0-30 and 30-100 cm) included particle-size distribution, dominant soil texture, organic carbon content, coarse fragments, bulk density, and porosity. After representative soil properties for the FAO soil units were estimated, these values were substituted into three different pedotransfer functions (PTF) models by Rawls et al. [1982], Saxton et al. [1986], and Batjes [1996a]. The Saxton PTF model was finally selected to calculate available water content because it only required particle-size distribution data and results closely agreed with the Rawls and Batjes PTF models that used both particle-size distribution and organic matter data. Soil water-holding capacities were then estimated by multiplying the available water content by the soil layer thickness and integrating over an effective crop root depth of 1 m or less (i.e., encountered shallow impermeable layers) and another soil depth data layer of 2.5 m or less.

  7. Understanding large-extent controls of soil organic carbon storage in relation to soil depth and soil-landscape systems

    NASA Astrophysics Data System (ADS)

    Mulder, Vera L.; Lacoste, Marine; Martin, Manuel P.; Richer-de-Forges, Anne; Arrouays, Dominique

    2015-08-01

    In this work we aimed at developing a conceptual framework in which we improve our understanding of the controlling factors for soil organic carbon (SOC) over vast areas at different depths. We postulated that variability in SOC levels may be better explained by modeling SOC within soil-landscape systems (SLSs). The study was performed in mainland France, and explanatory SOC models were developed for the sampled topsoil (0-30 cm) and subsoil (>30 cm), using both directed and undirected data-mining techniques. With this study we demonstrated that there is a shift in controlling factors both in space and depth which were mainly related to (1) typical SLS characteristics and (2) human-induced changes to SLSs. The controlling factors in relation to depth alter from predominantly biotic to more abiotic with increasing depth. Especially, water availability, soil texture, and physical protection control deeper stored SOC. In SLSs with similar SOC levels, different combinations of physical protection, the input of organic matter, and climatic conditions largely determined the SOC level. The SLS approach provided the means to partition the data into data sets that were having homogenous conditions with respect to this combination of controlling factors. This information may provide important information on the carbon storage and sequestration potential of a soil.

  8. Transport of Alachlor, Atrazine, Dicamba, and Bromide through Silt and Loam Soils

    NASA Astrophysics Data System (ADS)

    Tindall, J. A.

    2015-12-01

    The herbicides alachlor, atrazine, and dicamba, as well as bromide were applied to soils overlying the High Plains aquifer in Nebraska, to both macropore and non-macropore sites. Three of 6 study areas (exhibiting a high percentage of macropores) were used for analysis of chemical transport. Twelve intact soil cores (30 cm diameter; 40 cm height), were excavated (two each from 0-40 cm and 40-80 cm depths). The first three study areas and soil cores were used to study preferential flow characteristics using dye staining and to determine hydraulic properties; the remaining cores were treated the same as field macropore sites. Two undisturbed experimental field plots, each with a 1 m2 surface area, were established in each of the three macropore study areas. Each preferential plot was instrumented with suction lysimeters, tensiometers, and neutron access tubes - 10 cm increments to 80 cm - and planted in corn. Three study areas that did not exhibit macropores had alachlor, atrazine, and dicamba and bromide disked into the top 15 cm of soil; concentrations were tracked for 120 days - samples were collected on a grid, distributed within 3 plots measuring 50 m x 50 m each. Core samples were collected prior to and immediately after application, and then at 30, 60, and 120 days after application. Each lab core sample was in 15-cm lengths from 0-15 cm, 15-30 cm, 45-60 cm, and 75-90 cm. For areas exhibiting macropores, herbicides had begun to move between 10-15 days after application with concentrations peaking at various depths after heavy rainfall events. Field lysimeter samples showed increases in concentrations of herbicides at depths where laboratory data indicated greater percentages of preferential flowpaths. Concentrations of atrazine, alachlor and dicamba exceeding 0.30, 0.30, and 0.05 μg m1-1 respectively were observed with depth (10-30 cm and 50-70 cm) after two months following heavy rainfall events indicating that preferential flowpaths were a significant

  9. Legacy effects of grassland management on soil carbon to depth.

    PubMed

    Ward, Susan E; Smart, Simon M; Quirk, Helen; Tallowin, Jerry R B; Mortimer, Simon R; Shiel, Robert S; Wilby, Andrew; Bardgett, Richard D

    2016-08-01

    The importance of managing land to optimize carbon sequestration for climate change mitigation is widely recognized, with grasslands being identified as having the potential to sequester additional carbon. However, most soil carbon inventories only consider surface soils, and most large-scale surveys group ecosystems into broad habitats without considering management intensity. Consequently, little is known about the quantity of deep soil carbon and its sensitivity to management. From a nationwide survey of grassland soils to 1 m depth, we show that carbon in grassland soils is vulnerable to management and that these management effects can be detected to considerable depth down the soil profile, albeit at decreasing significance with depth. Carbon concentrations in soil decreased as management intensity increased, but greatest soil carbon stocks (accounting for bulk density differences), were at intermediate levels of management. Our study also highlights the considerable amounts of carbon in subsurface soil below 30 cm, which is missed by standard carbon inventories. We estimate grassland soil carbon in Great Britain to be 2097 Tg C to a depth of 1 m, with ~60% of this carbon being below 30 cm. Total stocks of soil carbon (t ha(-1) ) to 1 m depth were 10.7% greater at intermediate relative to intensive management, which equates to 10.1 t ha(-1) in surface soils (0-30 cm), and 13.7 t ha(-1) in soils from 30 to 100 cm depth. Our findings highlight the existence of substantial carbon stocks at depth in grassland soils that are sensitive to management. This is of high relevance globally, given the extent of land cover and large stocks of carbon held in temperate managed grasslands. Our findings have implications for the future management of grasslands for carbon storage and climate mitigation, and for global carbon models which do not currently account for changes in soil carbon to depth with management. PMID:26854892

  10. Chemical changes in soil charcoal of differing ages inferred from DRIFT spectra

    NASA Astrophysics Data System (ADS)

    Hobley, E. U.; Willgoose, G. R.; Frisia, S.; Jacobsen, G.

    2012-04-01

    Visible charcoal fragments were manually isolated from a sandy soil from the Southern Highlands of NSW, Australia, at depths of 0 - 30 cm and 30 - 60 cm. In the topsoil, the charcoal had a radiocarbon age of 85 ± 35 years BP, whereas the charcoal from the 30 - 60 cm layer was radiocarbon dated at 2540 ± 35 years BP. Diffuse reflectance FTIR (DRIFT) spectra of the charcoal reveal differences in both the number of peaks detected and their magnitudes. In the IR region 750 - 3800 cm-1, the charcoal from the lower depth had less peaks (140) than that of the topsoil (217). In the 1400 - 1600 cm-1 region, generally attributed to aromatics, the peaks were larger and more numerous (22 peaks) in the 0 - 30 cm sample than those of the 30 - 60 cm depth (14 peaks). The C-H stretch of alkenes and aromatics (3000 - 3100 cm-1) was similar at both depths, but the peak generally associated with the C-H stretch of alkanes (methyl and methylene groups) at 2850 - 3000 cm-1 was smaller in 30 - 60 cm depth than in the topsoil. In contrast to the reduction in aromatic and alkane signatures, oxidised forms were more pronounced in the older, deeper charcoal. Peaks associated with the free hydroxyl O-H stretch (alcohols and phenols) at 3640 - 3610 cm-1, carboxylic acids (910 - 950 cm-1), aliphatic O-H (alcohols) (1050 - 1150 cm-1) and cellulose-like structures (1020 cm-1), which contain a large number of uncondensed, oxidised rings, were larger in the charcoal from 30 - 60 cm than in that from the topsoil. Our results confirm that charcoal is highly persistent in soils, being retained for millennia. Aromatic structures are present in both younger and older charcoal, but decay leads to a reduction in the number and area of peaks detected at 1400 - 1600 cm-1, indicating less aromaticity. Alkane C-H also decreases with aging, probably attributable to its preferential degradation by soil microbes compared with condensed aromatic structures. Concurrent with diminished aromatic and alkane

  11. Digital mapping of soil organic carbon contents and stocks in Denmark.

    PubMed

    Adhikari, Kabindra; Hartemink, Alfred E; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B; Greve, Mogens H

    2014-01-01

    Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories. PMID:25137066

  12. Interannual variations of soil organic carbon fractions in unmanaged volcanic soils (Canary Islands, Spain).

    PubMed

    Armas-Herrera, Cecilia María; Mora, Juan Luis; Arbelo, Carmen Dolores; Rodríguez-Rodríguez, Antonio

    2012-10-01

    The stability over time of the organic C stocked in soils under undisturbed ecosystems is poorly studied, despite being suitable for detecting changes related to climate fluctuations and global warming. Volcanic soils often show high organic C contents due to the stabilization of organic matter by short-range ordered minerals or Al-humus complexes. We investigated the dynamics of different organic C fractions in volcanic soils of protected natural ecosystems of the Canary Islands (Spain) to evaluate the stability of their C pools. The study was carried out in 10 plots, including both undisturbed and formerly disturbed ecosystems, over two annual periods. C inputs to (litterfall) and outputs from (respiration) the soil, root C stocks (0-30 cm), soil organic C (SOC) fractions belonging to C pools with different degrees of biogeochemical stability -total oxidisable C (TOC), microbial biomass C (MBC), water soluble C (WSC), hot-water extractable C (HWC), humic C (HSC), - and total soil N (TN) (at 0-15 and 15-30 cm) were measured seasonally.A statistically significant interannual increase in CO(2) emissions and a decrease in the SOC, mainly at the expense of the most labile organic forms, were observed, while the root C stocks and litterfall inputs remained relatively constant over the study period. The observed changes may reflect an initial increase in SOC resulting from low soil respiration rates due to drought during the first year of study. The soils of nearly mature ecosystems were more apparently affected by C losses, while those undergoing the process of active natural regeneration exhibited disguised C loss because of the C sequestration trend that is characteristic of progressive ecological succession. PMID:23145325

  13. Environmental Controls of Soil Organic Carbon in Soils Across Amazonia

    NASA Astrophysics Data System (ADS)

    Quesada, Carlos Alberto; Paz, Claudia; Phillips, Oliver; Nonato Araujo Filho, Raimundo; Lloyd, Jon

    2015-04-01

    Amazonian forests store and cycle a significant amount of carbon on its soils and vegetation. Yet, Amazonian forests are now subject to strong environmental pressure from both land use and climate change. Some of the more dramatic model projections for the future of the Amazon predict a major change in precipitation followed by savanization of most currently forested areas, resulting in major carbon losses to the atmosphere. However, how soil carbon stocks will respond to climatic and land use changes depend largely on how soil carbon is stabilized. Amazonian soils are highly diverse, being very variable in their weathering levels and chemical and physical properties, and thus it is important to consider how the different soils of the Basin stabilize and store soil organic carbon (SOC). The wide variation in soil weathering levels present in Amazonia, suggests that soil groups with contrasting pedogenetic development should differ in their predominant mechanism of SOC stabilization. In this study we investigated the edaphic, mineralogical and climatic controls of SOC concentration in 147 pristine forest soils across nine different countries in Amazonia, encompassing 14 different WRB soil groups. Soil samples were collected in 1 ha permanent plots used for forest dynamics studies as part of the RAINFOR project. Only 0-30 cm deep averages are reported here. Soil samples were analyzed for carbon and nitrogen and for their chemical (exchangeable bases, phosphorus, pH) and physical properties, (particle size, bulk density) and mineralogy through standard selective dissolution techniques (Fe and Al oxides) and by semi-quantitative X-Ray diffraction. In Addition, selected soils from each soil group had SOC fractionated by physical and chemical techniques. Our results indicate that different stabilization mechanisms are responsible for SOC stabilization in Amazonian soils with contrasting pedogenetic level. Ferralsols and Acrisols were found to have uniform mineralogy

  14. Soil Biogeochemistry in the Ent DGVM

    NASA Astrophysics Data System (ADS)

    Kharecha, P. A.; Kiang, N. Y.; Aleinov, I.; Moorcroft, P.; Koster, R.

    2007-12-01

    As the global climate continues to warm in the 21st century, it will be vital to assess the degree of carbon cycle feedbacks from the terrestrial biosphere, particularly the soil. Global soil carbon stocks, which amount to approximately double the carbon stored in vegetation, could provide either positive or negative climate feedbacks, depending on a given ecosystem's response to warming. To predict changes in net terrestrial CO2 fluxes and belowground organic carbon storage, we have developed and evaluated a soil biogeochemistry submodel for the Ent dynamic global vegetation model currently being tested within the GISS GCM. It is a modified version of the soil submodel in the CASA biosphere model (Potter et al., Glob. Biogeoch. Cyc. 7, 1993). We have enhanced it to allow for explicit depth structure (2 soil layers, 0-30 cm and 30-100 cm), first-order inter-layer (vertical) soil organic carbon transport, and a variable-Q10 temperature dependence for soil microbial respiration. We have tested the soil model in numerous offline runs. To spin up the simulated carbon pools offline, we conducted multi-century runs using meteorological and ecological data from various FLUXNET field sites that represent 7 of the 8 GISS GCM plant functional types: tundra, grassland, shrubland, savanna, deciduous forest, evergreen needleleaf forest, and tropical rainforest (the eighth, cropland, will be dealt with in a separate study). We then compare the magnitudes of the simulated spun-up soil pools to soil carbon stock data from these field sites as well as the biome-aggregated data from Post et al. (Nature 317, 1985). Net ecosystem CO2 fluxes and soil respiration are also compared to site-specific measurements where available. Preliminary results suggest that simulated fluxes are reasonably close to measured values, but simulated carbon storage tends to be lower than the measurements. In addition to site-specific comparisons, we discuss the broader implications of our results, e.g., the

  15. Long-term rotation studies and the effect on soil organic carbon in cotton soils.

    NASA Astrophysics Data System (ADS)

    Braunack, M.; Hulugalle, N.; Rochester, I.

    2012-04-01

    carbon increased slightly in the surface layer over time. For E3 soil organic carbon increased in the soil surface, and even more rapidly in the 30-60 cm soil layer. In the 0-30 cm layer there was an increase in soil organic carbon in E2 and E3 and a decrease in E1. Profile soil water tended to be greater with minimal tillage and surface stubble retained treatments. It is concluded that a reduction in tillage when combined with crop rotation can reduce the rate of soil organic carbon decline and that there is potential for crop rotations to increase soil organic carbon in the 0-30cm soil layer over time. Exchangeable sodium percentage (ESP) tended to increase over time in E1 and remained constant in E2. ESP did not constrain growth in E3. Yield of cotton varied with seasonal conditions; however, yield has increased slowly with time in all experiments. Implications for tillage-stubble management are discussed.

  16. From 20cm to 1.5m: Is Digging Deeper Necessary?

    NASA Astrophysics Data System (ADS)

    Fissore, C.; Nater, E. A.; Dalzell, B. J.; Kolka, R.; Perry, C.

    2011-12-01

    Quantification of belowground carbon (C) currently stored in forest ecosystems is far from complete, especially for deeper soil horizons. Given logistical difficulties of sampling deep soils over large areas, much attention has been given to estimate deep SOC stocks indirectly. It is unknown whether C content in the top 20 cm of the mineral soil is an effective index for deep soil C storage across broad ranges of climate, forest type, and soil characteristics. The US Forest Service has a large record of aboveground and belowground (up to 20 cm depth) C data that could potentially be used to quantify deep SOC stocks if a suitable indirect estimation method can be developed. We followed and extended USDA FS Forest Inventory Analysis protocols to sample forest sites in the Midwest U.S. to determine C content up to 1.5m depth over a range of forest and soil types. Preliminary results show that, at hardwood sites, C percent in the top 20 cm of the mineral soil predicted only 28% of deep soil C in sandy soils and 20% in loamy soils. On a mass basis (mg C/cm3), such relationship was even weaker, suggesting that a number of biophysical variables affect SOC storage along the soil profile. Ongoing analyses will identify whether including additional factors such as forest type and soil chemical-physical characteristics will strengthen this relationship. The use of fractionation techniques and stable and radioactive isotopes will help illustrate SOC stabilization mechanisms.

  17. Switching 70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal by 3 MHz bipolar field

    NASA Astrophysics Data System (ADS)

    Li, Shiyang; Chen, Zhaojiang; Cao, Wenwu

    2016-06-01

    Polarization switching and associated electromechanical property changes at 3.0 MHz were investigated with and without a direct current (dc) bias for [001]c poled 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal. The results showed that the coercive field under a bipolar pulse at 3.0 MHz is 2.75 times as large as conventional defined Ec (2.58 kV/cm at 0.1 Hz), and a dc bias can further enlarge the driving field. Our results point to an innovative transducer operating mechanism at high frequencies since one could drive the crystal under much larger fields at high frequencies to produce much stronger signals from a small array element for deeper penetration imaging.

  18. [Distribution of soil organic carbon in surface soil along a precipitation gradient in loess hilly area].

    PubMed

    Sun, Long; Zhang, Guang-hui; Luan, Li-li; Li, Zhen-wei; Geng, Ren

    2016-02-01

    Along the 368-591 mm precipitation gradient, 7 survey sites, i.e. a total 63 investigated plots were selected. At each sites, woodland, grassland, and cropland with similar restoration age were selected to investigate soil organic carbon distribution in surface soil (0-30 cm), and the influence of factors, e.g. climate, soil depth, and land uses, on soil organic carbon distribution were analyzed. The result showed that, along the precipitation gradient, the grassland (8.70 g . kg-1) > woodland (7.88 g . kg-1) > farmland (7.73 g . kg-1) in concentration and the grassland (20.28 kg . m-2) > farmland (19.34 kg . m-2) > woodland (17.14 kg . m-2) in density. The differences of soil organic carbon concentration of three land uses were not significant. Further analysis of pooled data of three land uses showed that the surface soil organic carbon concentration differed significantly at different precipitation levels (P<0.00 1). Significant positive relationship was detected between mean annual precipitation and soil organic carbon concentration (r=0.838, P<0.001) in the of pooled data. From south to north (start from northernmost Ordos), i.e. along the 368-591 mm precipitation gradient, the soil organic carbon increased with annual precipitation 0. 04 g . kg-1 . mm-1, density 0.08 kg . m-2 . mm-1. The soil organic carbon distribution was predicted with mean annual precipitation, soil clay content, plant litter in woodland, and root density in farmland. PMID:27396128

  19. Characterizing the spatial variability of soil infiltration using apparent electrical conductivity

    NASA Astrophysics Data System (ADS)

    Castro Franco, Mauricio; Domenech, Marisa; Aparicio, Virginia; Costa, José Luis

    2013-04-01

    Implementation of irrigation systems and models of water flow and solute transport, requires continuous and accurate hydrological information. Apparent electrical conductivity (ECa) has been used to characterize the spatial behavior of soil properties. The objective was to characterize the spatial variability of soil infiltration at farm scale using ECa measurements. ECa measurements of a 42 ha farm were collected for the top 0-30cm (ECa(s)) and 0-90cm (ECa(d)) soil using the Veris® 3100. ECa maps were generated for both depths, using geostatistical interpolation techniques. From these maps, three general areas were delineated, named High, Medium, and Low ECa zones. At each zone, three sub samples were collected. Infiltration, altimetry (Alt) and effective depth (ED) were measured. Soil samples were taken at two depths 0-30 (Sh) and 30-60 (Dp). Bulk density (δb), clay content and organic matter (OM) were analyzed. Infiltration rate (i) was estimated using a disc infiltrometer. Soil series were Petrocalcic Paleudoll and Typic Argiudoll. Spatial variability of soil properties were analyzed by descriptive statistics. High ECa zones showed greater Alt and lesser ED. Likewise, Sh and Dp soil samples had greater δb and clay content, and lesser OM content. Medium and Low ECa zones were situated at similar areas of Alt and ED. Likewise, δb and OM content showed similar values at the two studied depths. In the Medium ECa zone, clay content was higher in Sh sampler. In general, the lowest i was in the High ECa zone, while in Medium and Low ECa zones, i values were similar. ECa was associated with clay content and OM, therefore with δb and i. It is concluded that spatial variability of soil infiltration could be characterized through ECa.

  20. Soil Organic Carbon Response to Cover Crop and Nitrogen Fertilization under Bioenergy Sorghum

    NASA Astrophysics Data System (ADS)

    Sainju, U. M.; Singh, H. P.; Singh, B. P.

    2015-12-01

    Removal of aboveground biomass for bioenergy/feedstock in bioenergy cropping systems may reduce soil C storage. Cover crop and N fertilization may provide additional crop residue C and sustain soil C storage compared with no cover crop and N fertilization. We evaluated the effect of four winter cover crops (control or no cover crop, cereal rye, hairy vetch, and hairy vetch/cereal rye mixture) and two N fertilization rates (0 and 90 kg N ha-1) on soil organic C (SOC) at 0-5, 5-15, and 15-30 cm depths under forage and sweet sorghums from 2010 to 2013 in Fort Valley, GA. Cover crop biomass yield and C content were greater with vetch/rye mixture than vetch or rye alone and the control, regardless of sorghum species. Soil organic C was greater with vetch/rye than rye at 0-5 and 15-30 cm in 2011 and 2013 and greater with vetch than rye at 5-15 cm in 2011 under forage sorghum. Under sweet sorghum, SOC was greater with cover crops than the control at 0-5 cm, but greater with vetch and the control than vetch/rye at 15-30 cm. The SOC increased at the rates of 0.30 Mg C ha-1 yr-1 at 0-5 cm for rye and the control to 1.44 Mg C ha-1 yr-1 at 15-30 cm for vetch/rye and the control from 2010 to 2013 under forage sorghum. Under sweet sorghum, SOC also increased linearly at all depths from 2010 to 2013, regardless of cover crops. Nitrogen fertilization had little effect on SOC. Cover crops increased soil C storage compared with no cover crop due to greater crop residue C returned to the soil under forage and sweet sorghum and hairy vetch/cereal rye mixture had greater C storage than other cover crops under forage sorghum.

  1. [Effects of biological regulated measures on active organic carbon and erosion-resistance in the Three Gorges Reservoir region soil].

    PubMed

    Huang, Ru; Huang, Lin; He, Bing-Hui; Zhou, Li-Jiang; Yu, Chuan; Wang, Feng

    2013-07-01

    To gain a better knowledge of characteristics of soils and provide a scientific basis for soil erosion control in the Three Gorges Reservoir Area, contents of aggregates and total soil organic carbon (SOC), as well as soil active organic carbon fractions including particulate organic carbon (POC), readily oxidized organic carbon (ROC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) in the 0-30 cm soil layer under seven different biological regulated measures were studied by the field investigation combined with the laboratory analysis. Results showed that the content of the SOC and active organic carbon fractions decreased with the increasing soil depth; the content of the SOC and active organic carbon fractions in 0-10 cm was significantly higher than that in 20-30 cm. The stability of soil aggregates were also significantly influenced by biological regulated measures, the content of > 0.25 mm water-stable aggregates in seven types of biological regulated measures was in the order of Koelreuteria bipinnata + Cassia suffruticasa > hedgerows > closed forest > natural restoration > economic forest > traditional planting > control plot, moreover, the content of 0.25 mm water-stable aggregates correlated positively with the content of SOC. Soils under different biological regulated measures all demonstrated fractal features, and soil under the measure of Koelreuteria bipinnata + Cassia suffruticasa was found to have the lowest value of fractal dimension and soil erodiable K, indicating a relatively strong structure stability and erosion-resistant capacity. Negative correlation was observed when compared the content of active organic carbon fractions with the soil erodiable K. It can be concluded that properties of soil can be managed through biological regulated measures; thence had an influence on the soil erosion-resistant capacity. PMID:24028016

  2. 77 FR 8877 - ICD-9-CM Coordination and Maintenance (C&M) Committee Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

    ... HUMAN SERVICES Centers for Disease Control and Prevention ICD-9-CM Coordination and Maintenance (C&M... Standards Staff, announces the following meeting. Name: ICD-9-CM Coordination and Maintenance (C&M... attend the ICD- 9-CM C&M meeting on March 5, 2012, must submit their name and organization by February...

  3. Quantity of Soil Organic Matter in the Upper 3 m of Soil in the Northern Circumpolar Permafrost Region

    NASA Astrophysics Data System (ADS)

    Hugelius, G.; Tarnocai, C.

    2012-12-01

    The current estimate for soil organic carbon (SOC) quantity in the northern circumpolar permafrost region (Tarnocai et al., 2009) is 191 Pg for topsoil (0-30 cm depth), 496 Pg for the upper 100 cm of soil and SOC mass to 300 cm soil depth is estimated to be 1024 Pg. In addition, storage in deeper (> 300 cm) Yedoma deposits (407 Pg) and deltaic deposits (241 Pg) brings the total estimate to 1672 Pg, of which 1466 Pg is stored in perennially frozen ground. The estimate for 0-1 m depth SOC mass is based on the Northern Circumpolar Soil Carbon Database (NCSCD), a geospatial database which links 1647 pedons from the northern permafrost regions to several digitized regional/national soil maps with a combined circumpolar coverage. This database has recently been published online and the data is available in several different file formats, including gridded files with different spatial resolutions. Files adapted for use in GIS or modeling applications (shape-files, TIFF-rasters and NetCDF files) are available for separate regions or with merged circumpolar coverage. Estimates for the 0-30 cm and 0-100 cm depth ranges based on the NCSCD are unlikely to be significantly changed or refined in the coming years. However, the emergence of high quality geospatial datasets with circumpolar coverage as well as applications of spatially distributed regression/kriging techniques in periglacial environments (e.g. Mishra and Riley, 2012) point towards complementary approaches that may significantly increase our knowledge of circumpolar SOC distribution. The present estimates of SOC mass in the 0-300 cm depth range is based on very limited field data (46 Canadian pedons), is accorded low to very low confidence and is not included in the spatially distributed NCSCD (Tarnocai et al., 2009). However, a compilation of additional pedon data is underway and an updated version of the NCSCD will be complemented with spatially distributed estimates of 100-200 cm and 200-300 cm depth SOCM based

  4. A new detailed map of total phosphorus stocks in Australian soil.

    PubMed

    Viscarra Rossel, Raphael A; Bui, Elisabeth N

    2016-01-15

    Accurate data are needed to effectively monitor environmental condition, and develop sound policies to plan for the future. Globally, current estimates of soil total phosphorus (P) stocks are very uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of total P in Australian soil. Data from several sources were harmonized to produce the most comprehensive inventory of total P in soil of the continent. They were used to produce fine spatial resolution continental maps of total P in six depth layers by combining the bootstrap, a decision tree with piecewise regression on environmental variables and geostatistical modelling of residuals. Values of percent total P were predicted at the nodes of a 3-arcsecond (approximately 90 m) grid and mapped together with their uncertainties. We combined these predictions with those for bulk density and mapped the total soil P stock in the 0-30 cm layer over the whole of Australia. The average amount of P in Australian topsoil is estimated to be 0.98 t ha(-1) with 90% confidence limits of 0.2 and 4.2 t ha(-1). The total stock of P in the 0-30 cm layer of soil for the continent is 0.91 Gt with 90% confidence limits of 0.19 and 3.9 Gt. The estimates are the most reliable approximation of the stock of total P in Australian soil to date. They could help improve ecological models, guide the formulation of policy around food and water security, biodiversity and conservation, inform future sampling for inventory, guide the design of monitoring networks, and provide a benchmark against which to assess the impact of changes in land cover, land use and management and climate on soil P stocks and water quality in Australia. PMID:26520615

  5. Spatial variability of soil carbon stock in the Urucu river basin, Central Amazon-Brazil.

    PubMed

    Ceddia, Marcos Bacis; Villela, André Luis Oliveira; Pinheiro, Érika Flávia Machado; Wendroth, Ole

    2015-09-01

    The Amazon Forest plays a major role in C sequestration and release. However, few regional estimates of soil organic carbon (SOC) stock in this ecoregion exist. One of the barriers to improve SOC estimates is the lack of recent soil data at high spatial resolution, which hampers the application of new methods for mapping SOC stock. The aims of this work were: (i) to quantify SOC stock under undisturbed vegetation for the 0-30 and the 0-100 cm under Amazon Forest; (ii) to correlate the SOC stock with soil mapping units and relief attributes and (iii) to evaluate three geostatistical techniques to generate maps of SOC stock (ordinary, isotopic and heterotopic cokriging). The study site is located in the Central region of Amazon State, Brazil. The soil survey covered the study site that has an area of 80 km(2) and resulted in a 1:10,000 soil map. It consisted of 315 field observations (96 complete soil profiles and 219 boreholes). SOC stock was calculated by summing C stocks by horizon, determined as a product of BD, SOC and the horizon thickness. For each one of the 315 soil observations, relief attributes were derived from a topographic map to understand SOC dynamics. The SOC stocks across 30 and 100 cm soil depth were 3.28 and 7.32 kg C m(-2), respectively, which is, 34 and 16%, lower than other studies. The SOC stock is higher in soils developed in relief forms exhibiting well-drained soils, which are covered by Upland Dense Tropical Rainforest. Only SOC stock in the upper 100 cm exhibited spatial dependence allowing the generation of spatial variability maps based on spatial (co)-regionalization. The CTI was inversely correlated with SOC stock and was the only auxiliary variable feasible to be used in cokriging interpolation. The heterotopic cokriging presented the best performance for mapping SOC stock. PMID:25918893

  6. Evaluation of soil moisture sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the measurement accuracy and repeatability of the EC-5 and 5TM soil volumetric water content (SVWC) sensors, MPS-2 and 200SS soil water potential (SWP) sensors, and 200TS soil temperature sensor. Six 183cm x 183cm x 71cm wooden compartments were built inside a greenhouse, and e...

  7. Spatial Variability of Soil Fertility Properties for Precision Agriculture in Southern Iran

    NASA Astrophysics Data System (ADS)

    Yasrebi, Jafar; Saffari, Mahboub; Fathi, Hamed; Karimian, Najafali; Emadi, Mostafa; Baghernejad, Majid

    The objective of this study was to determine the degree of spatial variability of soil chemical properties, soil texture and variance structure. Spatial distributions for 13 soil chemical properties and soil texture were examined in a fallow land in Bajgah, Fars province, Iran. Soil samples were collected at approximately 60 m2 at 0-30 cm depth and coordinates of each of the 100 points were recorded with GPS. The spatial distribution and spatial dependence level varied within location. The range of spatial dependence was found to vary within soil parameters. Phosphorous had the shortest range of spatial dependence (49.50 m) and percentage of calcium carbonate equivalent had the longest (181.94 m). All parameters exhibited strongly spatially dependent. The results demonstrate that within the same field, spatial patterns vary among several soil parameters. Soil nutrients were found to be affected by farmer management. Variography and kriging can be useful tools for designing effective soil sampling strategies and variable rate application of inputs for use in site-specific farming.

  8. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ∼1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (∼0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  9. Compositional Homogeneity of CM Parent Bodies

    NASA Astrophysics Data System (ADS)

    Vernazza, P.; Marsset, M.; Beck, P.; Binzel, R. P.; Birlan, M.; Cloutis, E. A.; DeMeo, F. E.; Dumas, C.; Hiroi, T.

    2016-09-01

    CM chondrites are the most common type of hydrated meteorites, making up ˜1.5% of all falls. Whereas most CM chondrites experienced only low-temperature (˜0°C–120°C) aqueous alteration, the existence of a small fraction of CM chondrites that suffered both hydration and heating complicates our understanding of the early thermal evolution of the CM parent body(ies). Here, we provide new constraints on the collisional and thermal history of CM-like bodies from a comparison between newly acquired spectral measurements of main-belt Ch/Cgh-type asteroids (70 objects) and existing laboratory spectral measurements of CM chondrites. It first appears that the spectral variation observed among CM-like bodies is essentially due to variations in the average regolith grain size. Second, the spectral properties of the vast majority (unheated) of CM chondrites resemble both the surfaces and the interiors of CM-like bodies, implying a “low” temperature (<300°C) thermal evolution of the CM parent body(ies). It follows that an impact origin is the likely explanation for the existence of heated CM chondrites. Finally, similarly to S-type asteroids and (2) Pallas, the surfaces of large (D > 100 km)—supposedly primordial—Ch/Cgh-type main-belt asteroids likely expose the interiors of the primordial CM parent bodies, a possible consequence of impacts by small asteroids (D < 10 km) in the early solar system.

  10. Tunability of optical gain (SWIR region) in type-II In0.70Ga0.30As/GaAs0.40Sb0.60 nano-heterostructure under high pressure

    NASA Astrophysics Data System (ADS)

    Nirmal, H. K.; Yadav, Nisha; Dalela, S.; Rathi, Amit; Siddiqui, M. J.; Alvi, P. A.

    2016-06-01

    The interest in applying an external pressure on a nano-heterostructure is to attempt to extract more information about the electronic structure through distortion of the electronic structure. This paper reports the tunability of the optical gain under the high pressure effect in M-shaped type-II In0.70Ga0.30As/GaAs0.40Sb0.60 symmetric lasing nano-heterostructure designed for SWIR generation. In order to simulate the optical gain, the heterostructure has been modeled with the help of six band k.p method. The 6×6 diagonalized k.p Hamiltonian has been solved to evaluate the valence sub-bands (i.e. light and heavy hole energies); and then optical matrix elements and optical gain within TE (Transverse Electric) mode has been calculated. For the injected carrier density of 5×1012/cm2, the optimized optical gain within TE mode is as high as ~9000/cm at the wavelength of ~1.95 μm, thus providing a very important alternative material system for the generation of SWIR wavelength region. The application of very high pressure (2, 5 and 8 GPa) on the structure along [110] direction shows that the gain as well as lasing wavelength both approach to higher values. Thus, the structure can be tuned externally by the application of high pressure within the SWIR region.

  11. Influence of soil moisture on soil respiration

    NASA Astrophysics Data System (ADS)

    Fer, Miroslav; Kodesova, Radka; Nikodem, Antonin; Klement, Ales; Jelenova, Klara

    2015-04-01

    The aim of this work was to describe an impact of soil moisture on soil respiration. Study was performed on soil samples from morphologically diverse study site in loess region of Southern Moravia, Czech Republic. The original soil type is Haplic Chernozem, which was due to erosion changed into Regosol (steep parts) and Colluvial soil (base slope and the tributary valley). Soil samples were collected from topsoils at 5 points of the selected elevation transect and also from the parent material (loess). Grab soil samples, undisturbed soil samples (small - 100 cm3, and large - 713 cm3) and undisturbed soil blocks were taken. Basic soil properties were determined on grab soil samples. Small undisturbed soil samples were used to determine the soil water retention curves and the hydraulic conductivity functions using the multiple outflow tests in Tempe cells and a numerical inversion with HYDRUS 1-D. During experiments performed in greenhouse dry large undisturbed soil samples were wetted from below using a kaolin tank and cumulative water inflow due to capillary rise was measured. Simultaneously net CO2 exchange rate and net H2O exchange rate were measured using LCi-SD portable photosynthesis system with Soil Respiration Chamber. Numerical inversion of the measured cumulative capillary rise data using the HYDRUS-1D program was applied to modify selected soil hydraulic parameters for particular conditions and to simulate actual soil water distribution within each soil column in selected times. Undisturbed soil blocks were used to prepare thin soil sections to study soil-pore structure. Results for all soil samples showed that at the beginning of soil samples wetting the CO2 emission increased because of improving condition for microbes' activity. The maximum values were reached for soil column average soil water content between 0.10 and 0.15 cm3/cm3. Next CO2 emission decreased since the pore system starts filling by water (i.e. aggravated conditions for microbes

  12. Prediction of soil organic carbon in forest areas of the Piedmont region, Northern Italy, using environmental variables: vegetation and topographic patterns effect.

    NASA Astrophysics Data System (ADS)

    Oueslati, Ines; Allamano, Paola; Bonifacio, Eleonora; Claps, Pierluigi; Laguardia, Giovanni

    2010-05-01

    Soil organic carbon (SOC) is one of the most important parameters affecting soil hydraulic properties. It is easily measured by chemical analyses, but it is highly variable in space. Therefore the definition of a methodology allowing for SOC spatial prediction with a reasonable accuracy is crucial in large scale studies. This study aims at predicting the spatial variability of the soil organic carbon concentration (%SOC) in forest topsoils in Piedmont (North-western Italy) using spatially referenced environmental factors related to terrain morphology, climate, and vegetation. In this region 122 soil profiles were available with soil organic carbon concentrations at depths of 0 -10 cm, 10 -20 cm, 20 -30 cm, 0 -20 cm and 0 -30 cm and in the horizons A, B and C. For each point terrain attributes were derived from a 50 meters pixel digital elevation model (DEM), using the SAGA geographic information system. In addition basic NDVI statistics, such as the mean, minimum and maximum values, and the Fourier series phases (F1 and F2) and amplitudes (A1 and A2) for the 12 months and 6 months periods were evaluated from the long term monthly average NDVI series obtained by SPOT-Vegetation data. Mean annual precipitation estimates were also available for each sample. A multiple regression analysis were applied to investigate the relationship between the %SOC in different layers and horizons and the environmental descriptors. The relationships that we found show that the NDVI parameters and the precipitation are statistically significant predictors (P

  13. Gas-Phase Oxidation of Cm+ and Cm2+ -- Thermodynamics of neutral and ionized CmO

    SciTech Connect

    Gibson, John K; Haire, Richard G.; Santos, Marta; Pires de Matos, Antonio; Marcalo, Joaquim

    2008-12-08

    Fourier transform ion cyclotron resonance mass spectrometry was employed to study the products and kinetics of gas-phase reactions of Cm+ and Cm2+; parallel studies were carried out with La+/2+, Gd+/2+ and Lu+/2+. Reactions with oxygen-donor molecules provided estimates for the bond dissociation energies, D[M+-O](M = Cm, Gd, Lu). The first ionization energy, IE[CmO], was obtained from the reactivity of CmO+ with dienes, and the second ionization energies, IE[MO+](M = Cm, La, Gd, Lu), from the rates of electron-transfer reactions from neutrals to the MO2+ ions. The following thermodynamic quantities for curium oxide molecules were obtained: IE[CmO]= 6.4+-0.2 eV; IE[CmO+]= 15.8+-0.4 eV; D[Cm-O]= 710+-45 kJ mol-1; D[Cm+-O]= 670+-40 kJ mol-1; and D[Cm2+-O]= 342+-55 kJ mol-1. Estimates for the M2+-O bond energies for M = Cm, La, Gd and Lu are all intermediate between D[N2-O]and D[OC-O]--i.e., 167 kJ mol-1< D[M2+-O]< 532 kJ mol-1 -- such that the four MO2+ ions fulfill the thermodynamic requirement for catalytic O-atom transport from N2O to CO. It was demonstrated that the kinetics are also favorable and that the CmO2+, LaO2+, GdO2+ and LuO2+ dipositive ions each catalyze the gas-phase oxidation of CO to CO2 by N2O. The CmO2+ ion appeared during the reaction of Cm+ with O2 when the intermediate, CmO+, was not collisionally cooled -- although its formation is kinetically and/or thermodynamically unfavorable, CmO2+ is a stable species.

  14. Using the Rasch model as an objective and probabilistic technique to integrate different soil properties

    NASA Astrophysics Data System (ADS)

    Rebollo, Francisco J.; Jesús Moral García, Francisco

    2016-04-01

    Soil apparent electrical conductivity (ECa) is one of the simplest, least expensive soil measurements that integrates many soil properties affecting crop productivity, including, for instance, soil texture, water content, and cation exchange capacity. The ECa measurements obtained with a 3100 Veris sensor, operating in both shallow (0-30 cm), ECs, and deep (0-90 cm), ECd, mode, can be used as an additional and essential information to be included in a probabilistic model, the Rasch model, with the aim of quantifying the overall soil fertililty potential in an agricultural field. This quantification should integrate the main soil physical and chemical properties, with different units. In this work, the formulation of the Rasch model integrates 11 soil properties (clay, silt and sand content, organic matter -OM-, pH, total nitrogen -TN-, available phosphorus -AP- and potassium -AK-, cation exchange capacity -CEC-, ECd, and ECs) measured at 70 locations in a field. The main outputs of the model include a ranking of all soil samples according to their relative fertility potential and the unexpected behaviours of some soil samples and properties. In the case study, the considered soil variables fit the model reasonably, having an important influence on soil fertility, except pH, probably due to its homogeneity in the field. Moreover, ECd, ECs are the most influential properties on soil fertility and, on the other hand, AP and AK the less influential properties. The use of the Rasch model to estimate soil fertility potential (always in a relative way, taking into account the characteristics of the studied soil) constitutes a new application of great practical importance, enabling to rationally determine locations in a field where high soil fertility potential exists and establishing those soil samples or properties which have any anomaly; this information can be necessary to conduct site-specific treatments, leading to a more cost-effective and sustainable field

  15. Soil Organic Carbon dynamics in agricultural soils of Veneto Region

    NASA Astrophysics Data System (ADS)

    Bampa, F. B.; Morari, F. M.; Hiederer, R. H.; Toth, G. T.; Giandon, P. G.; Vinci, I. V.; Montanarella, L. M.; Nocita, M.

    2012-04-01

    management of the EU territory by field observations of geo-referenced points. In 2009, a topsoil (0-30 cm) module was included to the survey and a subset of around 21,000 sites was sampled in 23 Member States. The second source is a soil survey monitoring pilot campaign carried in Veneto Region last year. The pilot campaign has been organized with the collaboration between JRC, University of Padova and ARPAV Veneto. The scope was to apply the LUCAS methodology to an experimental soil survey of 40 samples. The selection of the points to survey has been done on the basis of the LUCAS project related to Veneto Region, pedo-climatic and management unit conditions and the database on soils belonging to ARPAV Soil Unit, collected ante 2000. Data started to be investigated and permit to show changes in SOC content in a decade for different land use/cover and climatic areas. Through the bulk density data collected and the data already available from ARPAV library, it's possible to evaluate the Carbon stocks of Veneto region. Possible changes in Carbon can be related to land use changes and different strategies of management practices adopted over time.

  16. Relationship between the radiocesium interception potential and the transfer of radiocesium from soil to soybean cultivated in 2011 in Fukushima Prefecture, Japan.

    PubMed

    Takeda, Akira; Tsukada, Hirofumi; Yamaguchi, Noriko; Takeuchi, Megumi; Sato, Mutsuto; Nakao, Atsushi; Hisamatsu, Shun'ichi

    2014-11-01

    The concentration of radiocesium ((134)Cs and (137)Cs) in agricultural fields around Fukushima Dai-ichi Nuclear Power Plant (FDNPP) was elevated after the accident in March 2011. Evaluation of soil properties that influence phytoavailability of radiocesium is important for optimal soil management to minimize radiocesium transfer to crops. In this study, soybean grain and soil samples (0-15 cm) were collected from 46 locations in Fukushima Prefecture in 2011, and (137)Cs concentrations were measured. (137)Cs concentration ranges were 11-329 Bq kg(-1)-dry in soybean grain samples, and 0.29-2.49 kBq kg(-1)-dry in soil samples. The radiocesium interception potential (RIP) values in the soil samples ranged from 0.30 to 8.61 mol kg(-1). RIP negatively correlated with total carbon content and oxalate-extractable Si and Al + 1/2 Fe in the soils, suggesting that soils rich in organic matter and poorly crystalline clays tended to have lower RIP in this region. The soil-to-plant transfer factor for (137)Cs, analyzed in relation with various soil characteristics, varied by two orders of magnitude and was significantly negatively correlated with RIP and exchangeable K concentration in soil. The results show that RIP is useful for evaluating the efficiency of radiocesium transfer from soil to plants in this region. PMID:25036920

  17. Soil Aggregate Stability and Grassland Productivity Associations in a Northern Mixed-Grass Prairie.

    PubMed

    Reinhart, Kurt O; Vermeire, Lance T

    2016-01-01

    Soil aggregate stability data are often predicted to be positively associated with measures of plant productivity, rangeland health, and ecosystem functioning. Here we revisit the hypothesis that soil aggregate stability is positively associated with plant productivity. We measured local (plot-to-plot) variation in grassland community composition, plant (aboveground) biomass, root biomass, % water-stable soil aggregates, and topography. After accounting for spatial autocorrelation, we observed a negative association between % water-stable soil aggregates (0.25-1 and 1-2 mm size classes of macroaggregates) and dominant graminoid biomass, and negative associations between the % water-stable aggregates and the root biomass of a dominant sedge (Carex filifolia). However, variation in total root biomass (0-10 or 0-30 cm depths) was either negatively or not appreciably associated with soil aggregate stabilities. Overall, regression slope coefficients were consistently negative thereby indicating the general absence of a positive association between measures of plant productivity and soil aggregate stability for the study area. The predicted positive association between factors was likely confounded by variation in plant species composition. Specifically, sampling spanned a local gradient in plant community composition which was likely driven by niche partitioning along a subtle gradient in elevation. Our results suggest an apparent trade-off between some measures of plant biomass production and soil aggregate stability, both known to affect the land's capacity to resist erosion. These findings further highlight the uncertainty of plant biomass-soil stability associations. PMID:27467598

  18. An efficient In0.30Ga0.70N photoelectrode by decreasing the surface recombination centres in a H2SO4 aqueous solution

    NASA Astrophysics Data System (ADS)

    Li, Mingxue; Luo, Wenjun; Liu, Qi; Zhuang, Zhe; Li, Zhaosheng; Liu, Bin; Chen, Dunjun; Zhang, Rong; Yu, Tao; Zou, Zhigang

    2013-08-01

    The surface treatment of In0.30Ga0.70N photoelectrode in different acid electrolytes (HCl, HBr and a H2SO4 aqueous solution) has been investigated. The highest photocurrent is obtained after the surface treatment in H2SO4 aqueous solution. After H2SO4 treatment, the In0.30Ga0.70N photoelectrode responds to 550 nm and the maximum incident photon-to-current efficiency reaches about 58% under 400-430 nm, which is higher than the previous highest value (42%) on an InGaN photoelectrode. A possible mechanism is also proposed to explain the reason for the highest photocurrent enhancement after H2SO4 surface treatment. The results of the x-ray photoelectron spectroscopy, the inductively coupled atomic emission spectroscope and the electrochemical impedance spectra suggest that the surface segregation layer, as recombination centres of photo-generated holes and electrons, is decreased after H2SO4 surface treatment.

  19. Total Storage and Landscape Partitioning of Soil Organic Carbon and Phytomass Carbon in Siberia

    NASA Astrophysics Data System (ADS)

    Siewert, M. B.; Hanisch, J.; Weiss, N.; Kuhry, P.; Hugelius, G.

    2014-12-01

    We present results of detailed partitioning of soil organic carbon (SOC) and phytomass carbon (PC) from two study sites in Siberia. The study sites in the Tundra (Kytalyk) and the Taiga (Spasskaya Pad) reflect two contrasting environments in the continuous permafrost zone. In total 57 individual field sites (24 and 33 per study site respectively) have have been sampled for SOC and PC along transects cutting across different land covers. In Kytalyk the sampling depth for the soil pedons was 1 m depth. In Spasskaya Pad where the active layer was significantly deeper, we aimed for 2 m depth or tried to include at least the top of the permafrost. Here the average depth of soil profiles was 152 cm. PC was sampled from 1x1 m ground coverage plots. In Spasskaya Pad tree phytomass was also estimated on a 5x5 m plot. The SOC storage was calculated separately for the intervals 0-30 cm, 30-100 cm and 100-200 cm (the latter only for Spasskaya Pad), as well as for organic layer vs. mineral soil, active layer vs. permafrost and for cryoturbated soil horizons. Landscape partitioning was performed by thematic up-scaling using a vegetation based land cover classification of very high resolution (2x2 m) satellite imagery. Non-Metric Multidimensional Scaling (NMDS) was used to explore the relationship of SOC with PC and different soil and permafrost related variables. The results show that the different land cover classes can be considered distinct storages of SOC, but that PC is not significantly related to total SOC storage. At both study sites the 30-100 cm SOC storage is more important for the total SOC storage than the 0-30 cm interval, and large portions of the total SOC are stored in the permafrost. The largest contribution comes from wetland pedons, but highly cryoturbated individual non-wetland pedons can match these. In Kytalyk the landscape partitioning of SOC mostly follows large scale geomorphological features, while in Spasskaya pad forest type also has a large

  20. [Characteristics of soil nematode community in Abies georgei var. smithii forest gaps in south-east Tibet, China].

    PubMed

    Xue, Hui-Ying; Luo, Da-Qing

    2013-09-01

    In order to understand the characteristics of soil nematode community in the Abies georgei var. smithii forest gaps in southeast Tibet, an investigation was conducted to study the variations of soil nematode community at different depths of 0-30 cm soil layer in the gaps and non-gaps. The nematode individual density, diversity index, and trophic group index were taken to analyze the composition and structural characteristics of the soil nematode community. A total of 26801 soil nematodes belonging to 2 classes, 5 orders, and 64 genera were collected by shallow dish method. The nematode individual density was averagely 3552 ind x 100 g(-1) dry soil, and the individuals had a highly surface-gathering characteristics. In the gap soils, the dominant genera were Tylencholaimus and Filenchus, while the dominant trophic group was bacterivores. The soil organic matter was decomposed by both bacteria and fungi. The ecological index results showed that the nematodes diversity and richness were related to gap size. The characteristics of soil nematode community in the gaps were different from those in closed stand and forest open land, and this difference indicated the potential for using nematodes as the environmental indicator species. PMID:24417106

  1. Effect of spatial variability of soil properties on infiltration

    NASA Astrophysics Data System (ADS)

    Domenech, Marisa; Castro Franco, Mauricio; Aparicio, Virginia; Costa, José Luis

    2013-04-01

    Topography and soil properties are key determinants of spatial variability of water content. Prediction of soil hydraulic properties are essential for modeling water flow and solute transport. In the southeastern of Buenos Aires Province, the effect of the relief on soil spatial variability is result of the relationship between elevation and effective depth (ED). Digital elevation models (DEM) provide quantitive information about relief. The objective was to determine the effect of spatial variability of soil properties on infiltration. The field was 50 ha and the soil classes were vertic Hapludoll, typic and petrocalcic Argiudoll. ED was measured using Gidding_Soil_Sampler® in 30x30m grid size. Elevation data were measured ussing a DGPS Trimble_R3®. From this, a DEM was generated. Two elevation and ED areas were delineated named High and Low zones. Three soil samples were taken at each zone with three replications at depth 0-30 and 30-90 cm. Texture, bulk density (δb) and organic matter (OM) were determined. A disc infiltrometer was used to determine the water infiltration rate (i). Clay content (As) and OM were homogeneous in the profile of the High zone. However, As content at 30-90 cm decreased in the Low zone. At the High zone, δb ranged from 1.31 to 1.34 g cm-3 and was higher than at the Low zone (δb=1.16 - 1.27 g cm-3). Also the i had less variation at the High zone. Under pressure head of -1 cm , the i increased in the Low zone. At lower pressure heads, the i was greater in the High zone. Higher i at the Low zone could be due to major ED, textural heterogeneity and higher OM content. Textural homogeneity, shallow ED and high δb allowed a more stable i at the High zone. Using topography and ED is a promising way of characterizing soil hydraulic behavior and its spatial variability across a field.

  2. Windthrows increase soil carbon stocks in a central Amazon forest

    NASA Astrophysics Data System (ADS)

    dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; de Camargo, Plínio B.; Negrón-Juárez, Robinson I.; Lima, Adriano J. N.; Ribeiro, Gabriel H. P. M.; dos Santos, Joaquim; Higuchi, Niro

    2016-03-01

    Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha-1, mean ±95 % confidence interval) was marginally higher (p = 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity (r2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.

  3. Salinity altered root distribution and increased diversity of bacterial communities in the rhizosphere soil of Jerusalem artichoke.

    PubMed

    Yang, Hui; Hu, Jinxiang; Long, Xiaohua; Liu, Zhaopu; Rengel, Zed

    2016-01-01

    The interaction between roots and bacterial communities in halophytic species is poorly understood. Here, we used Jerusalem artichoke cultivar Nanyu 1 (NY-1) to characterise root distribution patterns and determine diversity and abundance of bacteria in the rhizosphere soil under variable salinity. Root growth was not inhibited within the salinity range 1.2 to 1.9 g salt/kg, but roots were mainly confined to 0-20 cm soil layer vertically and 0-30cm horizontally from the plant centre. Root concentrations of K(+), Na(+), Mg(2+) and particularly Ca(2+) were relatively high under salinity stress. High salinity stress decreased soil invertase and catalase activity. Using a next-generation, Illumina-based sequencing approach, we determined higher diversity of bacteria in the rhizosphere soil at high than low salinity. More than 15,500 valid reads were obtained, and Proteobacteria, Acidobacteria, Bacteroidetes and Actinobacteria predominated in all samples, accounting for >80% of the reads. On a genus level, 636 genera were common to the low and high salinity treatments at 0-5 cm and 5-10 cm depth. The abundance of Steroidobacter and Sphingomonas was significantly decreased by increasing salinity. Higher Shannon and Chao 1 indices with increasing severity of salt stress indicated that high salt stress increased diversity in the bacterial communities. PMID:26852800

  4. Radiocarbon measurements of soil organic matter (SOM) and soil CO2 efflux provide unique insights into the SOM dynamics of managed loblolly pine plantations

    NASA Astrophysics Data System (ADS)

    Vogel, J. G.; Schuur, E. A.; Bracho, R.; Jokela, E. J.

    2011-12-01

    Soil organic matter (SOM) cycling between soils and the atmosphere affects a wide range of important ecosystem functions. However the key processes controlling this cycle, fine root inputs and heterotrophic respiration, are poorly understood primarily because they are difficult to directly measure in the field. Radiocarbon measurements and simple models can be used to evaluate the relative influence of these processes on SOM cycling. Here we used radiocarbon measurements of density separated SOM, and root respiration, microbial respiration, and soil CO2 efflux to examine the relative effect of two forestry practices, fertilization and the genetic control of planted seedlings, on SOM cycling in two loblolly pine plantation forests in north central Florida. Our primary hypothesis was that greater aboveground growth would correspond to increased inputs of C to the soil as root biomass, and a greater efflux of CO2 from roots and soil microbes. For the density separated fractions, the light fraction (LF) (<1.6 g cm-3) was nearly 98% of the SOM in these sandy soils, and the LF decreased significantly (p<0.05) with increasing levels of fertilization for the A horizon (~0-30 cm). Light fraction radiocarbon values ranged from 66-127% and tended to be more enriched in bomb carbon, or older, with increasing levels of fertilization. Based on a significant reduction in fine root biomass with fertilization, we estimate that the smaller mass of the LF and its older age were the result of less fine root contributions of C to the LF pool. The alternative hypothesis, that fertilization increased SOM turnover, was not supported. To determine if changes in root biomass reflected changes in root respiration in soil CO2 efflux, we estimated radiocarbon values for root and microbial respiration, and soil CO2 efflux in order to partition the components in soil CO2 efflux. Radiocarbon estimates of microbial respiration (0-15 cm depth) and root respiration fractions ranged from 55-67% and

  5. 8-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8-cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5-cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8-cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  6. Measurements of soil and canopy exchange rates in the Amazon rain forest using sup 222 Rn

    SciTech Connect

    Trumbore, S.E. Lamont-Doherty Geological Observatory, Palisades, NY ); Keller, M. ); Wofsy, S.C. ); Da Costa, J.M. )

    1990-09-20

    Measurements of the emission of {sup 222}Rn from Amazon forest soils, and profiles of {sup 222}Rn in air were used to study the ventilation of the soil atmosphere and the nocturnal forest canopy. The emission of {sup 222}Rn from the yellow clay soils dominant in the study area averaged 0.38 {plus minus} 0.07 atom cm{sup {minus}2} s{sup {minus}1}. Nearby sand soils had similar fluxes, averaging 0.30 {plus minus} 0.07 atom cm{sup {minus}2} s{sup {minus}1}. The effective diffusivity in the clay soil (0.008 {plus minus} 0.004 cm{sup 2} s{sup {minus}1}), was lower than that for the sand soil (0.033 {plus minus} 0.030 cm{sup 2} s{sup {minus}1}). Profiles of {sup 222}Rn and CO{sub 2} in air showed steepest concentration gradients in the layer between 0 and 3 m above the soil surface. Aerodynamic resistances calculated for this layer from {sup 222}Rn and CO{sub 2} varied from 1.6 to 18 s cm{sup {minus}1}, with greater resistance during the afternoon than at night. Time averaged profiles of {sup 222}Rn in the forest canopy measured during the evening and night were combined with the soil flux measurements to compute the resistance of the subcanopy to exchange with overlying air. The integrated nocturnal rate of gas exchange between the canopy layer (0 to 41 m) and overlying atmosphere based on {sup 222}Rn averaged 0.33 {plus minus} 0.15 cm s{sup {minus}1}. An independent estimate of gas exchange, based on 13 nights of CO{sub 2} profiles, averaged 0.21 {plus minus} 0.40 cm s{sup {minus}1}. These exchange rates correspond to flushing times for the 41 m canopy layer of 3.4 and 5.5 hours, respectively. Comparison of {sup 222}Rn and CO{sub 2} profiles show that the nocturnal production of CO{sub 2} by above-ground vegetation was about 20% of the soil emission source, consistent with data from eddy-correlation experiments.

  7. Epitaxial Pb(Zrx,Ti1-x)O3 (0.30 ≤ x ≤ 0.63) films on (100)MgO substrates for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Yeager, Charles B.; Trolier-McKinstry, Susan

    2012-10-01

    Piezoelectric energy harvesting systems are of interest as a long-term power source for low-power wireless sensors. Transduction from elastic to electrical energy depends on the product of the piezoelectric charge and voltage coefficients; optimization of this figure of merit is an essential step towards improved microelectromechanical energy harvesting devices. This work reports on the composition dependence on the dielectric and piezoelectric properties of epitaxial {001}Pb(Zrx, Ti1-x)O3 films grown by chemical solution deposition and crystallized at 650 °C on (100)Pt//(100)MgO substrates for 0.63 ≤ x ≤ 0.30. The power generation figure of merit shows the greatest magnitude at compositions near x = 0.52, for which e31,f = -12 C/m2 and ɛr = 420. Lattice parameters were determined as a function of [Zr] to assess when comparisons to single domain properties calculated from Landau-Devonshire theory were appropriate. Furthermore, films doped with 1 at. % Mn had the highest observed figure of merit, four times greater than of AlN.

  8. Inflow measurement made with a laser velocimeter on a helicopter model in forward flight. Volume 3: Rectangular planform blades at an advance ratio of 0.30

    NASA Technical Reports Server (NTRS)

    Elliott, Joe W.; Althoff, Susan L.; Sailey, Richard H.

    1988-01-01

    An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (micron sub infinity = 0.30). The measurements were made with a two component Laser Velocimeter (LV) one chord above the plane formed by the path of the rotor tips (tip path plane). A conditional sampling technique was employed to determine the azimuthal position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 180 separate locations in order to clearly define the inflow character. These data are presented without analysis.

  9. Synthesis and electrical characterization of Li 0.30Ca 0.35TaO 3 perovskite synthesized via a polymerized complex route

    NASA Astrophysics Data System (ADS)

    Pham, Quoc Nghi; Vijayakumar, Murugesan; Bohnke, Claude; Bohnke, Odile

    2005-06-01

    The synthesis of Li 0.30Ca 0.35TaO 3 perovskite by a Pechini-type polymerizable precursor method is carefully described. The thermal decomposition of the precursor and the formation of a pure perovskite phase were investigated by means of differential thermal analysis-thermogravimetric analysis (DTA-TGA) and XRD techniques. A pure and well-crystallized phase has been obtained at a lower temperature and with a much shorter synthesis time than the phase obtained by conventional solid-state reaction method. The morphology of the powder after heating at 1300 °C was observed by laser granulometry, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Impedance spectroscopy data allowed us to determine the electrical properties, i.e., permittivity and dc-conductivity, of the bulk and grain boundaries. The results are discussed on the assumption of the brick layer model.

  10. Chilled Mirror Dew Point Hygrometer (CM) Handbook

    SciTech Connect

    Ritsche, MT

    2005-01-01

    The CM systems have been developed for the ARM Program to act as a moisture standard traceable to National Institute of Standards and Technology (NIST). There are three CM systems that are each fully portable, self-contained, and require only 110 V AC power. The systems include a CM sensor, air sampling and filtration system, a secondary reference (Rotronic HP043 temperature and relative humidity sensor) to detect system malfunctions, a data acquisition system, and data storage for more than one month of 1-minute data. The CM sensor directly measures dew point temperature at 1 m, air temperature at 2 m, and relative humidity at 2 m. These measurements are intended to represent self-standing data streams that can be used independently or in combinations.

  11. Astrophysics with the 60-cm telescope

    NASA Astrophysics Data System (ADS)

    Zverko, J.

    2014-03-01

    Observational programs and selection from scientific results with the 60-cm telescope achieved at the Skalnaté Pleso Observatory since its putting into operation is reviewed: novae, eclipsing and interacting binaries, symbiotic stars, cataclysmic variables, chemically peculiar stars, comets. Possible targets among newly detected binaries are proposed for determining orbital parameters using the new spectrograph of the 60-cm telescope at the Stará Lesná Observatory.

  12. Pedotransfer functions for Irish soils - estimation of bulk density (ρb) per horizon type

    NASA Astrophysics Data System (ADS)

    Reidy, B.; Simo, I.; Sills, P.; Creamer, R. E.

    2016-01-01

    Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international data sets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon type bulk densities using local known bulk density data sets. Then the best performing of the pedotransfer functions were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data were missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0-30 and 30-50 cm horizon depths. In general the horizons with the largest known data sets had the best predictions, using the recalibrated and validated pedotransfer functions.

  13. Pedotransfer functions for Irish soils - estimation of bulk density (ρb) per horizon type

    NASA Astrophysics Data System (ADS)

    Reidy, B.; Simo, I.; Sills, P.; Creamer, R. E.

    2015-10-01

    Soil bulk density is a key property in defining soil characteristics. It describes the packing structure of the soil and is also essential for the measurement of soil carbon stock and nutrient assessment. In many older surveys this property was neglected and in many modern surveys this property is omitted due to cost both in laboratory and labour and in cases where the core method cannot be applied. To overcome these oversights pedotransfer functions are applied using other known soil properties to estimate bulk density. Pedotransfer functions have been derived from large international datasets across many studies, with their own inherent biases, many ignoring horizonation and depth variances. Initially pedotransfer functions from the literature were used to predict different horizon types using local known bulk density datasets. Then the best performing of the pedotransfer functions, were selected to recalibrate and then were validated again using the known data. The predicted co-efficient of determination was 0.5 or greater in 12 of the 17 horizon types studied. These new equations allowed gap filling where bulk density data was missing in part or whole soil profiles. This then allowed the development of an indicative soil bulk density map for Ireland at 0-30 and 30-50 cm horizon depths. In general the horizons with the largest known datasets had the best predictions, using the recalibrated and validated pedotransfer functions.

  14. Regional scale assessment of soil predictors of groundwater phosphate (P) levels in acidic sandy agricultural soils

    NASA Astrophysics Data System (ADS)

    Mabilde, Lisa

    2016-04-01

    Possible factors affecting the leaching of P to the groundwater in the Belgian sandy area are examined via regression analysis. The main objective is to investigate the dependency of phreatic groundwater phosphate concentrations (Flemish VMM monitoring net, monitoring period 2010-2013) on soil phosphate saturation degree (PSD) (1994-1997 mapping for Flemish Land Agency) (n = 1032). Additionally explored parameters include: depth distributions of Fe- and Al-oxides, sorbed P and phosphate sorption capacity (PSC) and soil pH. Interpolated data of these soil parameters in 3 depth layers (0-30, 30-60, 60-90 cm) were generated by ordinary kriging. Secondly, we assessed the significance of other edaphic factors potentially controlling the groundwater P: topsoil organic carbon content (OC %), soil clay content and fluctuation of the groundwater table. Overall, the mean PSD halved with each 30 cm depth layer (56 > 24 > 13 %) and was correlated to groundwater PO43‑ level. The statistical significance of the correlation with groundwater PO43‑ concentrations increased with depth layer. The poor correlation (R2 = 0.01) between PSD and groundwater phosphate concentration indicates that many factors, other than soil P status, control the transport of P from soil solution to the groundwater in Belgian sandy soils. A significant (P<0.01) positive non-linear relationship was found between groundwater PO43‑concentration and pHKCl in all three studied depth layers, again increasingly with depth. Within the pH range of the 30-60 cm layer (pHKCl 4.0-5.7) PO4‑ solubility should increase with pH. Elevated soil OC levels surprisingly co-occurred with low groundwater PO43‑ concentrations (r = -0.18, P<0.01, n = 191). Groundwater PO43‑ was furthermore significantly and positively correlated to clay % in both the 0-15 cm (r = 0.15, τ = 0.25, P<0.01, n = 1032) and 60-90 cm (r = 0.13, τ = 0.20, P<0.01, n = 1032) depth increments. These positive correlations were unexpected and

  15. Correlated alteration effects in CM carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael E.

    1996-07-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production and increases as alteration proceeds. These parameters define the first CM alteration scale that relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison ≤ Bells < Pollen ≤ Murray < Mighei < Nogoya < Cold Bokkeveld. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values for the whole-rock chemistry of CM chondrites reveals several correlations. A positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. The abundance of trapped planetary 36Ar decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase (s) by aqueous reactions. Because low temperature fluid-rock reactions are generally associated with large isotopic mass fractionation factors, we also compared our model predictions with δ18O values for bulk CM samples. Although some of these data are

  16. Snowmelt timing alters shallow but not deep soil moisture in the Sierra Nevada

    NASA Astrophysics Data System (ADS)

    Blankinship, Joseph C.; Meadows, Matthew W.; Lucas, Ryan G.; Hart, Stephen C.

    2014-02-01

    Roughly one-third of the Earth's land surface is seasonally covered by snow. In many of these ecosystems, the spring snowpack is melting earlier due to climatic warming and atmospheric dust deposition, which could greatly modify soil water resources during the growing season. Though snowmelt timing is known to influence soil water availability during summer, there is little known about the depth of the effects and how long the effects persist. We therefore manipulated the timing of seasonal snowmelt in a high-elevation mixed-conifer forest in a Mediterranean climate during consecutive wet and dry years. The snow-all-gone (SAG) date was advanced by 6 days in the wet year and 3 days in the dry year using black sand to reduce the snow surface albedo. To maximize variation in snowmelt timing, we also postponed the SAG date by 8 days in the wet year and 16 days in the dry year using white fabric to shade the snowpack from solar radiation. We found that deeper soil water (30-60 cm) did not show a statistically significant response to snowmelt timing. Shallow soil water (0-30 cm), however, responded strongly to snowmelt timing. The drying effect of accelerated snowmelt lasted 2 months in the 0-15 cm depth and at least 4 months in the 15-30 cm depth. Therefore, the legacy of snowmelt timing on soil moisture can persist through dry periods, and continued earlier snowmelt due to climatic warming and windblown dust could reduce near-surface water storage and availability to plants and soil biota.

  17. Variability of water content and of depth profiles of global fallout 137Cs in grassland soils and the resulting external gamma-dose rates.

    PubMed

    Schimmack, W; Steindl, H; Bunzl, K

    1998-04-01

    137Cs from global fallout of nuclear weapon testings in the 1950s and 1960s was determined in successive layers (0-30 cm) of eight undisturbed grassland soils in Bavaria, Germany. The maximum activity concentration was found in soil layers between 4 and 15 cm below the surface. Using the vertical distribution of the cesium activity, which varied considerably from site to site, the mean residence half-time of 137Cs from global fallout in each soil layer was evaluated with a compartment model. These values ranged from 1.0 to 6.3 years/cm. The mean residence half-time averaged over all soil layers and all sites was 2.7 +/- 1.4 years/cm and, thus, about twice the corresponding residence half-time of the Chernobyl-derived 137Cs as determined in the same soil layers (also in 1993). The dose rate of the external gamma-radiation due to 137Cs from global fallout in the soil determined from the depth distributions varied between 0.34 and 0.57 (mean: 0.45 +/- 0.07) nGy/h per kBq/m2. The effect of soil water content on the dose rate was studied by considering four states of the soil, from water content zero to complete water saturation of the total pore volume. It was shown that the difference between the dose rates at the permanent wilting point and the field capacity, which both represent the most relevant water contents of soils, was only 10% of the dose rate at the permanent wilting point for all sites. PMID:9615340

  18. Continued Selenium Biofortification of Carrots and Broccoli Grown in Soils Once Amended with Se-enriched S. pinnata.

    PubMed

    Bañuelos, Gary S; Arroyo, Irvin S; Dangi, Sadikshya R; Zambrano, Maria C

    2016-01-01

    Selenium (Se) biofortification has been practiced in Se-deficient regions throughout the world primarily by adding inorganic sources of Se to the soil. Considering the use of adding organic sources of Se could be useful as an alternative Se amendment for the production of Se-biofortified food crops. In this multi-year micro-plot study, we investigate growing carrots and broccoli in soils that had been previously amended with Se-enriched Stanleya pinnata Pursh (Britton) three and 4 years prior to planting one and two, respectively. Results showed that total and extractable Se concentrations in soils (0-30 cm) were 1.65 mg kg(-1) and 88 μg L(-1), and 0.92 mg kg(-1) and 48.6 μg L(-1) at the beginning of the growing season for planting one and two, respectively. After each respective growing season, total Se concentrations in the broccoli florets and carrots ranged from 6.99 to 7.83 mg kg(-1) and 3.15 to 6.25 mg kg(-1) in planting one and two, respectively. In broccoli and carrot plant tissues, SeMet (selenomethionine) was the predominant selenoamino acid identified in Se aqueous extracts. In postharvest soils from planting one, phospholipid fatty acid (PLFA) analyses showed that amending the soil with S. pinnata exerted no effect on the microbial biomass, AMF (arbuscular mycorrhizal fungi), actinomycetes and Gram-positive and bacterial PLFA at both 0-5 and 0-30 cm, respectively, 3 years later. Successfully producing Se-enriched broccoli and carrots 3 and 4 years later after amending soil with Se-enriched S. pinnata clearly demonstrates its potential source as an organic Se enriched fertilizer for Se-deficient regions. PMID:27602038

  19. Correlated Alteration Effects in CM Carbonaceous Chondrites

    NASA Astrophysics Data System (ADS)

    Zolensky, Michael E.; Browning, Lauren B.; McSween, Harry Y., Jr.

    1996-01-01

    Three parameters are proposed to determine the relative extent of alteration in CM chondrites. The mineralogic alteration index monitors the relative progress of coupled substitutions in the progressive alteration of cronstedtite to Mg-serpentine, and increases with increasing alteration. To calculate values of this index, an algorithm has been developed to estimate the average matrix phyllosilicate composition in individual CM chondrites. The second parameter is the volume percent of isolated matrix silicates, which decreases with progressive alteration due to mineral hydration. Finally, the volume percent of chondrule alteration monitors the extent of chondrule phyllosilicate production, and increases as alteration proceeds. These parameters define the first CM alteration scale that-relies on multiple indicators of progressive alteration. The following relative order of increasing alteration is established by this model: Murchison less than or equal to Bells less than Pollen less than or equal to Murray less than Mighei less than Nogoya less than Cold Bokkeveld. Bulk delta18O values generally increase with progressive alteration, providing additional support for this sequence. The relative degree of aqueous processing Cochabamba and Boriskino experienced is less precisely constrained, although both fall near the middle of this sequence. A comparison between the mineralogic alteration index and literature values of the whole-rock chemistry of CM chondrites reveals several correlations. For example, a positive, nearly linear correlation between bulk H content and progressive CM alteration suggests an approximately constant production rate of new phyllosilicates relative to the mineralogical transition from cronstedtite to Mg-serpentine. Furthermore, the abundance of trapped planetary Ar-36 decreases systematically in progressively altered CM chondrites, suggesting the wholesale destruction of primary noble gas carrier phase(s) by aqueous reactions. Multiple

  20. Detection of Thermal 2 cm and 1 cm Formaldehyde Emission in NGC 7538

    NASA Astrophysics Data System (ADS)

    Yuan, Liang; Araya, E. D.; Hofner, P.; Kurtz, S.; Pihlstrom, Y.

    2011-05-01

    Formaldehyde is a tracer of high density gas in massive star forming regions. The K-doublet lines from the three lowest rotational energy levels of ortho-formaldehyde correspond to wavelengths of 6, 2 and 1 cm. Thermal emission of these transitions is rare, and maser emission has only been detected in the 6 cm line. NGC 7538 is an active site of massive star formation in the Galaxy, and one of only a few regions known to harbor 6 cm formaldehyde (H2CO) masers. Using the NRAO 100 m Green Bank Telescope (GBT), we detected 2 cm H2CO emission toward NGC 7538 IRS1. The velocity of the 2 cm H2CO line is very similar to the velocity of one of the 6 cm H2CO masers but the linewidth is greater. To investigate the nature of the 2 cm emission, we conducted observations of the 1 cm H2CO transition, and obtained a cross-scan map of the 2 cm line. We detected 1 cm emission and found that the 2 cm emission is extended (greater than 30"), which implies brightness temperatures of ˜0.2 K. Assuming optically thin emission, LTE, and that the 1 cm and 2 cm lines originate from the same volume of gas, both these detections are consistent with thermal emission of gas at ˜30 K. We conclude that the 1 cm and 2 cm H2CO lines detected with the GBT are thermal, which implies molecular densities above ˜105 cm-3. LY acknowledges support from WIU. PH acknowledges partial support from NSF grant AST-0908901.

  1. Nitrate as a Mobile Anion: The Relevance of Abiotic Retention to Soil Solution Fluxes

    NASA Astrophysics Data System (ADS)

    Strahm, B. D.; Brousseau, P. A.; Knoepp, J. D.

    2012-12-01

    Atmospheric nitrogen (N) deposition has increased over the last century, a trend predicted to continue into the future. These additions can exceed the N retention capacity of terrestrial ecosystems, resulting in net watershed N export and subsequent declines in terrestrial productivity and surface water quality. Understanding the spatial and temporal relationships in net NO3- retention or production is crucial in identifying areas susceptible to this global change factor in the future. This study was conducted to evaluate the surface (0-30 cm) and subsurface (30-60 cm) soil solution NO3- fluxes in watersheds with different land use histories along an N deposition gradient at the Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of the United States that have shown different patterns of NO3- export and overall retention historically. Duplicate resin-based lysimeters were used to collect NO3- in percolating soil solution at three depths (0, 30, 60 cm) at 42 individual plots across four watersheds on a seasonal basis for the duration of one year. Using batch equilibration techniques, NO3- sorption was characterized for each genetic soil horizon at each plot. Parameters describing the sorptive behavior were derived and related to observed flux measurements. Our results indicate that both surface and whole (0-60 cm) soils generally act as a sink for NO3- and that the relative sink strength of soils showed no relationship with disturbance history or ambient atmospheric N deposition. The source-sink dynamics of subsurface soils were more variable spatially, but showed no clear seasonal trend. Perhaps most surprising is that the source-sink dynamics of the two soil depths exhibited a strong reciprocal relationship. Where the sink strength of the surface soils was low, the subsurface soils exhibited their highest retention capacity. Conversely, where the surface soils were most retentive, the subsurface soils tended to act as a net source of NO3-. Nitrate

  2. Influence of variable topsoil replacement depths on soil chemical parameters within a coal mine in northeastern Wyoming, USA

    SciTech Connect

    Schladweiler, B.K.; Vance, G.F.; Legg, D.E.; Munn, L.C.; Haroian, R.

    2004-10-15

    Uniform topsoil replacement depths on coal mine reclaimed areas have been mandated by USA federal and state regulations; however, soils of the premine landscape are not naturally uniform in depth and vary in physical, chemical, and biological characteristics. In addition, uniform topsoil depths may actually hinder the development of diverse reclaimed plant communities. We studied the effect of varying topsoil replacement depth treatments (15, 30, and 56 cm) on soil and backfill pH, electrolytic conductivity (EC), and sodium adsorption ratio (SAR) within a reclaimed coal mine study area. Backfill material (also known as spoil) at this site did not possess levels of pH, EC, and SAR that were detrimental to plant growth. There was only a slight reduction in pH, EC, and SAR within the upper 15 cm depth in the reclaimed topsoil treatments with a general increase of EC and SAR in the lower portion of the replaced soil profile. Some downward movement of soluble salts within the reclaimed treatments was evident despite low precipitation. For examples, SAR in the 0-15 cm depth over all reclaimed treatments was lower in 2002 than 2000-2001, and the 0-30 cm portion of the reclaimed soil profile had reduced pH and EC, while the 30-60 cm portion had increased EC and SAR. It is anticipated that soil quality differences in terms of pH, EC, and SAR between topsoil depth treatments will be enhanced with time. Comparison of the reclaimed area to the native reference areas suggested numerous depth differences as a result of homogeneity of the replaced topsoil vs. undisturbed soil profiles.

  3. Probing lepton asymmetry with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2014-09-01

    We investigate the issue of how accurately we can constrain the lepton number asymmetry ξ{sub ν}=μ{sub ν}/T{sub ν} in the Universe by using future observations of 21 cm line fluctuations and cosmic microwave background (CMB). We find that combinations of the 21 cm line and the CMB observations can constrain the lepton asymmetry better than big-bang nucleosynthesis (BBN). Additionally, we also discuss constraints on ξ{sub ν} in the presence of some extra radiation, and show that the 21 cm line observations can substantially improve the constraints obtained by CMB alone, and allow us to distinguish the effects of the lepton asymmetry from the ones of extra radiation.

  4. CV and CM chondrite impact melts

    NASA Astrophysics Data System (ADS)

    Lunning, Nicole G.; Corrigan, Catherine M.; McSween, Harry Y.; Tenner, Travis J.; Kita, Noriko T.; Bodnar, Robert J.

    2016-09-01

    Volatile-rich and typically oxidized carbonaceous chondrites, such as CV and CM chondrites, potentially respond to impacts differently than do other chondritic materials. Understanding impact melting of carbonaceous chondrites has been hampered by the dearth of recognized impact melt samples. In this study we identify five carbonaceous chondrite impact melt clasts in three host meteorites: a CV3red chondrite, a CV3oxA chondrite, and a regolithic howardite. The impact melt clasts in these meteorites respectively formed from CV3red chondrite, CV3oxA chondrite, and CM chondrite protoliths. We identified these impact melt clasts and interpreted their precursors based on their texture, mineral chemistry, silicate bulk elemental composition, and in the case of the CM chondrite impact melt clast, in situ measurement of oxygen three-isotope signatures in olivine. These impact melts typically contain euhedral-subhedral olivine microphenocrysts, sometimes with relict cores, in glassy groundmasses. Based on petrography and Raman spectroscopy, four of the impact melt clasts exhibit evidence for volatile loss: these melt clasts either contain vesicles or are depleted in H2O relative to their precursors. Volatile loss (i.e., H2O) may have reduced the redox state of the CM chondrite impact melt clast. The clasts that formed from the more oxidized precursors (CV3oxA and CM chondrites) exhibit phase and bulk silicate elemental compositions consistent with higher intrinsic oxygen fugacities relative to the clast that formed from a more reduced precursor (CV3red chondrite). The mineral chemistries and assemblages of the CV and CM chondrite impact melt clasts identified here provide a template for recognizing carbonaceous chondrite impact melts on the surfaces of asteroids.

  5. Critical Evaluation of 0-30 km Profile Information in Ground-Based Zenith-Sky and Satellite-Measured Backscattered UV Radiation

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan; Petropavlovskikh, Irina; Deluishi, John; Einaudi, Franco (Technical Monitor)

    2000-01-01

    We now have several decades of experience in deriving vertical ozone profiles from the measurements of diffuse ultraviolet radiation by both ground and satellite-based instruments using Umkehr and BUV techniques. Continuing technological advances are pushing the state-of-the-art of these measurements to high spectral resolution and broader wavelength coverage. These modern instruments include the ground-based Brewer and satellite-based Global Ozone Monitoring Experiment (GOME) instruments, as well as advanced instruments being developed by ESA(SCIAMACHY), Netherlands(OMI) and Japan(ODUS). However, one of the issues that remains unresolved is the 0-30 km ozone profile information retrievable from these measurements. Though it is commonly believed that both the Umkehr and the satellite-based BUV techniques have very limited profile information below 30 km, there are those who argue that the data from these instruments should continue to be reported in this altitude range for they compare well with ozonesondes and hence there is useful scientific information. Others claim that the limitations of the Umkehr and BUV techniques are largely due to their low spectral resolution, and that the profile information below 30 km can be greatly improved by going to high spectral resolution instruments, such as Brewer and GOME. The purpose of this paper is to provide a critical evaluation of the 0-30 km ozone profile information in the various UV remote sensing techniques. We use a database of individual ozone profiles created using ozonesondes and SAGE and 4D ozone fields generated by data assimilation techniques to simulate radiances measured by the various techniques. We then apply a common inversion approach to all the methods to systematically examine how much profile information is available simply from the knowledge of total ozone, how much additional profile information is added by the traditional Dobson Umkehr and satellite buv techniques, and how much better one can do

  6. Influence of Soil Solution Salinity on Molybdenum Adsorption by Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molybdenum (Mo) adsorption on five arid-zone soils from California was investigated as a function of equilibrium solution Mo concentration (0-30 mg L-1), solution pH (4-8), and electrical conductivity (EC = 0.3 or 8 dS m-1). Molybdenum adsorption decreased with increasing pH. An adsorption maximum...

  7. Effects of biochar and elevated soil temperature on soil microbial activity and abundance in an agricultural system

    NASA Astrophysics Data System (ADS)

    Bamminger, Chris; Poll, Christian; Marhan, Sven

    2014-05-01

    As a consequence of Global Warming, rising surface temperatures will likely cause increased soil temperatures. Soil warming has already been shown to, at least temporarily, increase microbial activity and, therefore, the emissions of greenhouse gases like CO2 and N2O. This underlines the need for methods to stabilize soil organic matter and to prevent further boost of the greenhouse gas effect. Plant-derived biochar as a soil amendment could be a valuable tool to capture CO2 from the atmosphere and sequestrate it in soil on the long-term. During the process of pyrolysis, plant biomass is heated in an oxygen-low atmosphere producing the highly stable solid matter biochar. Biochar is generally stable against microbial degradation due to its chemical structure and it, therefore, persists in soil for long periods. Previous experiments indicated that biochar improves or changes several physical or chemical soil traits such as water holding capacity, cation exchange capacity or soil structure, but also biotic properties like microbial activity/abundance, greenhouse gas emissions and plant growth. Changes in the soil microbial abundance and community composition alter their metabolism, but likely also affect plant productivity. The interaction of biochar addition and soil temperature increase on soil microbial properties and plant growth was yet not investigated on the field scale. To investigate whether warming could change biochar effects in soil, we conducted a field experiment attached to a soil warming experiment on an agricultural experimental site near the University of Hohenheim, already running since July 2008. The biochar field experiment was set up as two-factorial randomized block design (n=4) with the factors biochar amendment (0, 30 t ha-1) and soil temperature (ambient, elevated=ambient +2.5° C) starting from August 2013. Each plot has a dimension of 1x1m and is equipped with combined soil temperature and moisture sensors. Slow pyrolysis biochar from the C

  8. Impact of Natural Conditioners on Water Retention, Infiltration and Evaporation Characteristics of Sandy Soil

    NASA Astrophysics Data System (ADS)

    Abdel-Nasser, G.; Al-Omran, A. M.; Falatah, A. M.; Sheta, A. S.; Al-Harbi, A. R.

    Soil conditioners i.e., natural deposits and organic fertilizer are used for alleviate some of poor physical properties of sandy soils such as low water retention and inefficient water use, especially in arid and semi-arid regions such as in Saudi Arabia conditions. The present study aims to investigate the impact of clay deposits and organic fertilizer on water characteristics, cumulative infiltration and intermittent evaporation of loamy sand soil. Soil sample was collected from surface layer (0-30 cm depth) of the Agricultural Experiment and Research Station at Dierab, 40 km south west of Riyadh, Saudi Arabia. Two samples of clay deposits (CD#22 and CD#23) collected from Khyleis area, Jeddah-Madina road in addition of commercial Organic Fertilizer (OF) were used in the present study. The experiments were done during August to December 2005 in soil physics laboratory, the soil was mixed with clay deposits and organic fertilizer at rates of 0, 1, 2.5, 5.0 and 10.0% (w/w). The transparent PVC columns were packed with soil to depth of 30 cm every 5.0 cm intervals to insure a homogeneity of soil in columns. The clay deposits (CD#22 and CD#23) and Organic Fertilizer (OF) mixed with the soil were packed in the upper 0-5.0 cm of each soil column. The infiltration experiment was done using a flooding apparatus (Marriot device) with constant head of 3.0 cm over the soil surface. The cumulative infiltration and wetting front depth as a function of time were recorded. The evaporation experiment was conducted in 40 cm long transparent sectioned Lucite cylinders (5.0 cm ID). Fifty millimeters of tap water were applied weekly for three wetting/drying cycles. Cumulative evaporation against time was measured daily by weighing each soil column. The soil moisture distribution at the end of the experiment was determined gravimetrically for each 5.0 cm interval. The results indicated that the three conditioners significantly increased the water constants of mixed soil (i.e., SWC, FC

  9. The Multidimensional Curriculum Model (MdCM)

    ERIC Educational Resources Information Center

    Vidergor, Hava E.

    2010-01-01

    The multidimensional Curriculum Model (MdCM) helps teachers to better prepare gifted and able students for our changing world, acquiring much needed skills. It is influenced by general learning theory of constructivism, notions of preparing students for 21st century, Teaching the Future Model, and current comprehensive curriculum models for…

  10. The 150/220 cm Schmidt telescope.

    NASA Astrophysics Data System (ADS)

    Bao, Ke-Ren; Li, De-Pei; Yi, Mei-Liang; Zhu, Li-Qing; Li, Chang-Jin; Xu, Jian-Hua; Zhu, Neng-Hong; Wang, Lang-Juan; Zheng, Yi-Jin

    1990-09-01

    This paper deals with the overall design of the 150/220 cm Schmidt telescope. The optics, main structure, main mirror cell and the focus keeping device, achromatic Schmidt control cell, hydrostatic bearing of polar axis, drive, CCD auto-guider, and multi microcomputer control system are discussed in detail.

  11. Characterization of 8-cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Williamson, W. S.

    1984-01-01

    Development of 8 cm ion thruster technology which was conducted in support of the Ion Auxiliary Propulsion System (IAPS) flight contract (Contract NAS3-21055) is discussed. The work included characterization of thruster performance, stability, and control; a study of the effects of cathode aging; environmental qualification testing; and cyclic lifetesting of especially critical thruster components.

  12. [Community characteristics of soil nematode in Abies georgei var. smithii forest in Sejila Mountain of Tibet, Southwest China].

    PubMed

    Xue, Hui-Ying; Luo, Da-Qing; Yu, Bao-Zheng

    2012-12-01

    In order to understand the present status of nematode diversity in soil ecosystem of Abies georgei var. smithii forest, the typical forest type in subalpine zone of southeastern Tibet, an investigation was made on the nematode community in different soil layers of 0-30 cm depth from the summer, 2010 to the spring, 2011. The nematode individual density, diversity index, and trophic group index were taken to analyze the composition and structural characteristics of the soil nematode community. A total of 7915 soil nematodes belonging to 2 classes, 6 orders, 38 families, and 67 genera were collected by shallow dish method. The nematode individual density was averagely 620 nematodes x 100 g(-1) dry soil, and the nematode individuals in surface soil layer (0-5 cm) accounted for 56.9% of the total, indicating the obvious surface gathering characteristics of the nematode community. Tylencholaimus, Helicotylenchus, and Plectus were the dominant genus. Plant-parasite nematode was the dominant trophic group, while fungi-feeding nematode had the largest proportion among the non plant-parasite nematodes. Soil organic matter was mainly decomposed by fungi. The ANOVA analysis indicated that there were no significant differences in the Shannon, Pielou, Margalef, and Simpson indices of soil nematode community among different seasons. The Pielou index had no significant difference among different soil layers, while the differences of Shannon, Margalef, and Simpson indices tended to be increased with increasing soil depth. It was concluded that the A. georgei var. smithii forest ecosystem in Sejila Mountain had a high maturity, with strong resistance to environment disturbances. PMID:23479883

  13. Measurement of electron effective mass ratios in Hg1-xCdxTe for 0.20 <= x <= 0.30 between 77K and 296K

    NASA Astrophysics Data System (ADS)

    Clarke, F. W.; Balevieius, S.; McDonald, J. K.; Grisham, J. A.

    2004-10-01

    Effective mass ratios, m*, of electrons in near intrinsic and n-type Hg1-xCdxTe for 0.20 <= x <= 0.30 over the temperature range 77 K <= T <= 296 K were measured using Faraday rotation spectroscopy. Effective masses were found to be about twice as large at room temperature as band edge effective mass, m*be, calculations. Measured effective masses diverge further from the theoretical formulations as temperature increases which appears to be due to a thermal excitation effect that is not accounted for in theoretical calculations. These calculations can be corrected using a linear correction factor, m**, where the true effective mass ratio, m* = m** m*be, where m** was found empirically to be m** = 4.52 x 10-3 T + 0.78. Carrier concentrations were measured using Hall or van der Pauw tests. Soldered contacts to high mobility materials like HgCdTe using even the purest indium solder inevitably result in contamination that can add significant numbers of impurity carriers to the material and severely decrease mobility. A simple method of burnishing contacts to the material without heat using indium solder is presented. These cold contacts do not effect the material properties and are very effective in n-type HgCdTe making good physically strong contacts that remain ohmic to at least 10 K. This is a review paper.

  14. Mapping of reciprocal space of La0.30CoO2 in 3D: Analysis of superstructure diffractions and intergrowths with Co3O4

    NASA Astrophysics Data System (ADS)

    Brázda, Petr; Palatinus, Lukáš; Klementová, Mariana; Buršík, Josef; Knížek, Karel

    2015-07-01

    We have used electron diffraction tomography and powder X-ray diffraction to elucidate the structural properties of layered cobaltate γ-La0.30CoO2. The structure consists of hexagonal sheets of edge-sharing CoO6 octahedra interleaved by lanthanum monolayers. The La3+ cations occupy only one third of available P2 sites, forming a 2-dimensional a√3×a√3 superstructure in a-b plane. The results show that there exists no order in the mutual relative shift between the neighbouring La interlayers within the a-b plane. This is manifested in the observed monotonous decrease of the diffracted intensity of the superstructure diffractions along c* in both X-ray and electron diffraction data. The observed lack of stacking order differentiates the LaxCoO2 from its Ca and Sr analogues where at least a partial stacking order of the cationic interlayers is manifested in experimental data published in literature.

  15. Stability Investigation of a Blunted Cone and a Blunted Ogive with a Flared Cylinder Afterbody at Mach Numbers from 0.30 to 2.85

    NASA Technical Reports Server (NTRS)

    Coltrane, Lucille C.

    1959-01-01

    A cone with a blunt nose tip and a 10.7 deg cone half angle and an ogive with a blunt nose tip and a 20 deg flared cylinder afterbody have been tested in free flight over a Mach number range of 0.30 to 2.85 and a Reynolds number range of 1 x 10(exp 6) to 23 x 10(exp 6). Time histories, cross plots of force and moment coefficients, and plots of the longitudinal force,coefficient, rolling velocity, aerodynamic center, normal- force-curve slope, and dynamic stability are presented. With the center-of-gravity location at about 50 percent of the model length, the models were both statically and dynamically stable throughout the Mach number range. For the cone, the average aerodynamic center moved slightly forward with decreasing speeds and the normal-force-curve slope was fairly constant throughout the speed range. For the ogive, the average aerodynamic center remained practically constant and the normal-force-curve slope remained practically constant to a Mach number of approximately 1.6 where a rising trend is noted. Maximum drag coefficient for the cone, with reference to the base area, was approximately 0.6, and for the ogive, with reference to the area of the cylindrical portion, was approximately 2.1.

  16. Soil Organic and Inorganic Carbon Stocks in Yanqi Basin of Northwestern China: A Study of Land Use Impact

    NASA Astrophysics Data System (ADS)

    Wang, J.; Wang, X.; Zhang, J.

    2011-12-01

    Soil carbon storage is an important element in the global carbon budgets. Although soil organic carbon (SOC) is low on arid land, there is evidence of a large amount of soil inorganic carbon (SIC). Here, we present a study of soil carbon dynamics, which was carried out in the central Xinjiang, i.e., the Yanqi Basin. The objective of this study is to examine the effect of land use on both SOC and SIC. We sampled 20 profiles to 100 cm depth, which are covered with little vegetation (i.e., desert land), shrub, crop and grass. We used three methods to measure SOC and SIC contents. Soil organic C content are determined using the automated CNS analyzer, the traditional Walkleyand Black method and Loss-on-ignition at 375°C for 17 hours, and soil inorganic C content by the automated CNS analyzer, pressure calimeter method and Loss-on-ignition from 375°C to 800°C. There are high correlations in both SOC and SIC among all three methods (Figure 1). Our results show that both SOC and SIC follow an order: desert land < shrub land < cropland0-30 cm depth, and from >10 kg m-2, to >50 kg m-2, respectively, for the 0-100 cm profile. On average, SIC counts >75% of the total soil carbon stock across all the land use types (Figure 2). Our study suggests that agricultural development on desert and shrub land is likely to increase soil organic/inorganic carbon storage.

  17. Soil organic carbon in the Sanjiang Plain of China: storage, distribution and controlling factors

    NASA Astrophysics Data System (ADS)

    Mao, D. H.; Wang, Z. M.; Li, L.; Miao, Z. H.; Ma, W. H.; Song, C. C.; Ren, C. Y.; Jia, M. M.

    2015-03-01

    The accurate estimation of soil organic carbon (SOC) storage and determination of its pattern-controlling factors is critical to understanding the ecosystem carbon cycle and ensuring ecological security. The Sanjiang Plain, an important grain production base in China, is typical of ecosystems, yet its SOC storage and pattern has not been fully investigated because of insufficient soil investigation. In this study, 419 soil samples obtained in 2012 for each of the three soil depth ranges 0-30, 30-60, and 60-100 cm and a geostatistical method are used to estimate the total SOC storage and density (SOCD) of this region. The results give rise to 2.32 Pg C for the SOC storage and 21.20 kg m-2 for SOCD, which is higher than the mean value for the whole country. The SOCD shows notable changes in lateral and vertical distribution. In addition, vegetation, climate, and soil texture, as well as agricultural activities, are demonstrated to have remarkable impacts on the variation in SOCD of this region. Soil texture has stronger impacts on the distribution of SOCD than climate in the Sanjiang Plain. Specifically, clay content can explain the largest proportion of the SOC variations (21.2% in the top 30 cm) and is the most dominant environmental controlling factor. Additionally, the effects of both climate and soil texture on SOCD show a weakening with increasing soil layer depth. This study indicates that reducing the loss of SOC requires effective conservation and restoration efforts of wetlands and forestlands, as well as sensible fertilization. The results from this study provide the most up-to-date knowledge on the storage and pattern of SOC in the Sanjiang Plain and have important implications for the determination of ecosystem carbon budgets and understanding ecosystem services.

  18. The Effect of Afforestation on Soil Moisture Content in Northeastern China.

    PubMed

    Yao, Yitong; Wang, Xuhui; Zeng, Zhenzhong; Liu, Yongwen; Peng, Shushi; Zhu, Zaichun; Piao, Shilong

    2016-01-01

    Widespread afforestation programs sequester carbon from the atmosphere and mitigate the rising of atmospheric carbon dioxide (CO2). Meanwhile, afforestation carbon sequestration may cost soil water. However, changes in soil moisture content (SMC) after large-scale afforestation or reforestation have rarely been quantified. In this study, we measured changes in SMC following afforestation using a paired plots method with data from 757 plots in Northeastern China. We found a marginally significant decline in soil moisture content of the top 1-m soil (SMC0-1m) after afforestation (P = 0.08) at the regional scale. The SMC responses to afforestation also vary across species. For example, significant SMC decrease are found for Populus spp. plantations (P < 0.05) and plantations of Pinus sylvestris var. mongolica (P < 0.05). Splitting the first meter of the soil profile into different depth intervals revealed that SMC declined significantly in shallow layers (0-30 cm) for Populus spp. and Pinus sylvestris var. mongolica. We also found that when SMC in the control exceeded a specific threshold, SMC for all five tree species considered tended to decrease, suggesting that the effects of afforestation on soil hydrology vary across different regions. PMID:27513001

  19. Hydrogen-Broadened Water from 50 to 300 cm-1 and 1300 to 4000 cm-1

    NASA Technical Reports Server (NTRS)

    Brown, L.; Peterson, D.; Plymate, C.

    1995-01-01

    To support remote sensing of the outer planets, absorption spectra of H2O broadened by H2 were recorded at room temperature using two Fourier transform spectrometers. The data from 1300 to 4000 cm-1 were obtained at 0.012 cm-1 resolution with the McMath FTS located at Kitt Peak National Observatory/National Solar Observatory. The remainder of the spectral data from 55 to 320 cm-1 were taken at 0.0056 cm-1 with the Bruker FTS.

  20. 15 cm multipole gas ion thruster

    NASA Technical Reports Server (NTRS)

    Isaacson, G. C.; Kaufman, H. R.

    1976-01-01

    A 15-cm multipole thruster was operated on argon and xenon. The multipole approach used has been shown capable of low discharge losses and flat ion beam profiles with a minimum of redesign. This approach employs low magnetic field strengths and flat or cylindrical sheet-metal parts, hence is suited to rapid optimization and scaling. Only refractory metal cathodes were used in this investigation.

  1. Constraining dark matter through 21-cm observations

    NASA Astrophysics Data System (ADS)

    Valdés, M.; Ferrara, A.; Mapelli, M.; Ripamonti, E.

    2007-05-01

    Beyond reionization epoch cosmic hydrogen is neutral and can be directly observed through its 21-cm line signal. If dark matter (DM) decays or annihilates, the corresponding energy input affects the hydrogen kinetic temperature and ionized fraction, and contributes to the Lyα background. The changes induced by these processes on the 21-cm signal can then be used to constrain the proposed DM candidates, among which we select the three most popular ones: (i) 25-keV decaying sterile neutrinos, (ii) 10-MeV decaying light dark matter (LDM) and (iii) 10-MeV annihilating LDM. Although we find that the DM effects are considerably smaller than found by previous studies (due to a more physical description of the energy transfer from DM to the gas), we conclude that combined observations of the 21-cm background and of its gradient should be able to put constrains at least on LDM candidates. In fact, LDM decays (annihilations) induce differential brightness temperature variations with respect to the non-decaying/annihilating DM case up to ΔδTb = 8 (22) mK at about 50 (15) MHz. In principle, this signal could be detected both by current single-dish radio telescopes and future facilities as Low Frequency Array; however, this assumes that ionospheric, interference and foreground issues can be properly taken care of.

  2. Mapmaking for precision 21 cm cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Tegmark, Max; Liu, Adrian; Ewall-Wice, Aaron; Hewitt, Jacqueline N.; Morales, Miguel F.; Neben, Abraham R.; Parsons, Aaron R.; Zheng, Haoxuan

    2015-01-01

    In order to study the "Cosmic Dawn" and the Epoch of Reionization with 21 cm tomography, we need to statistically separate the cosmological signal from foregrounds known to be orders of magnitude brighter. Over the last few years, we have learned much about the role our telescopes play in creating a putatively foreground-free region called the "EoR window." In this work, we examine how an interferometer's effects can be taken into account in a way that allows for the rigorous estimation of 21 cm power spectra from interferometric maps while mitigating foreground contamination and thus increasing sensitivity. This requires a precise understanding of the statistical relationship between the maps we make and the underlying true sky. While some of these calculations would be computationally infeasible if performed exactly, we explore several well-controlled approximations that make mapmaking and the calculation of map statistics much faster, especially for compact and highly redundant interferometers designed specifically for 21 cm cosmology. We demonstrate the utility of these methods and the parametrized trade-offs between accuracy and speed using one such telescope, the upcoming Hydrogen Epoch of Reionization Array, as a case study.

  3. 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.

  4. Measurable relationship between bright galaxies and their faint companions in WHL J085910.0+294957, a galaxy cluster at z = 0.30: vestiges of infallen groups?

    SciTech Connect

    Lee, Joon Hyeop; Lee, Hye-Ran; Kim, Minjin; Seon, Kwang-Il; Kim, Sang Chul; Yang, Soung-Chul; Ree, Chang Hee; Lee, Jong Chul; Jeong, Hyunjin; Ko, Jongwan; Choi, Changsu

    2014-08-20

    The properties of satellite galaxies are closely related to their host galaxies in galaxy groups. In cluster environments, on the other hand, the interaction between close neighbors is known to be limited. Our goal is to examine the relationships between host and satellite galaxies in the harsh environment of a galaxy cluster. To achieve this goal, we study a galaxy cluster WHL J085910.0+294957 at z = 0.30 using deep images obtained with CQUEAN CCD camera mounted on the 2.1 m Otto Struve Telescope. After member selection based on the scaling relations of photometric and structural parameters, we investigate the relationship between bright (M{sub i} ≤ –18) galaxies and their faint (–18 < M{sub i} ≤ –15) companions. The weighted mean color of faint companion galaxies shows no significant dependence (<1σ to bootstrap uncertainties) on cluster-centric distance and local luminosity density as well as the luminosity and concentration of an adjacent bright galaxy. However, the weighted mean color shows marginal dependence (∼2.2σ) on the color of an adjacent bright galaxy when the sample is limited to bright galaxies with at least two faint companions. By using a permutation test, we confirm that the correlation in color between bright galaxies and their faint companions in this cluster is statistically significant with a confidence level of 98.7%. The statistical significance increases if we additionally remove non-members using the Sloan Digital Sky Survey photometric redshift information (∼2.6σ and 99.3%). Our results suggest three possible scenarios: (1) vestiges of infallen groups, (2) dwarf capturing, and (3) tidal tearing of bright galaxies.

  5. Modeling the air-soil transport pathway of perfluorooctanoic acid in the mid-Ohio Valley using linked air dispersion and vadose zone models

    NASA Astrophysics Data System (ADS)

    Shin, Hyeong-Moo; Ryan, P. Barry; Vieira, Verónica M.; Bartell, Scott M.

    2012-05-01

    As part of an extensive modeling effort on the air-soil-groundwater transport pathway of perfluorooctanoic acid (PFOA), this study was designed to compare the performance of different air dispersion modeling systems (AERMOD vs. ISCST3), and different approaches to handling incomplete meteorological data using a data set with substantial soil measurements and a well characterized point source for air emissions. Two of the most commonly used EPA air dispersion models, AERMOD and ISCST3, were linked with the EPA vadose zone model PRZM-3. Predicted deposition rates from the air dispersion model were used as input values for the vadose zone model to estimate soil concentrations of PFOA at different depths. We applied 34 years of meteorological data including hourly surface measurements from Parkersburg Airport and 5 years of onsite wind direction and speed to the air dispersion models. We compared offsite measured soil concentrations to predictions made for the corresponding sampling depths, focusing on soil rather than air measurements because the offsite soil samples were less likely to be influenced by short-term variability in emission rates and meteorological conditions. PFOA concentrations in surface soil (0-30 cm depth) were under-predicted and those in subsurface soil (>30 cm depth) were over-predicted compared to observed concentrations by both linked air and vadose zone model. Overall, the simulated values from the linked modeling system were positively correlated with those observed in surface soil (Spearman's rho, Rsp = 0.59-0.70) and subsurface soil (Rsp = 0.46-0.48). This approach provides a useful modeling scheme for similar exposure and risk analyses where the air-soil-groundwater transport is a primary contamination pathway.

  6. Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape.

    PubMed

    Andraski, B J; Jackson, W A; Welborn, T L; Böhlke, J K; Sevanthi, Ritesh; Stonestrom, D A

    2014-05-01

    Perchlorate (ClO) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0-30 cm) ClO with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [ (Sessé & Moc. ex DC.) Coville] ClO; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO in relation to soil and plant reservoirs and cycling. Soil ClO ranged from 0.3 to 5.0 μg kg. Within settings, valley floor ClO was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, = 0.42; leaf, = 0.74) identified topographic and soil effects on ClO deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO concentrations and Cl/ClO molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO flux was 343 mg ha yr, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO (1310 mg ha) was identified as a previously unrecognized but important and active reservoir. Nitrate δO analyses of atmospheric deposition and soil supported the leaf-cycled-ClO input hypothesis. This study provides basic data on ClO distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems. PMID:25602827

  7. Influence of buffer-layer construction and substrate orientation on the electron mobilities in metamorphic In{sup 0.70}Al{sup 0.30}As/In{sup 0.76}Ga{sup 0.24}As/In{sup 0.70}Al{sup 0.30}As structures on GaAs substrates

    SciTech Connect

    Kulbachinskii, V. A.; Oveshnikov, L. N.; Lunin, R. A.; Yuzeeva, N. A.; Galiev, G. B.; Klimov, E. A.; Pushkarev, S. S.; Maltsev, P. P.

    2015-07-15

    The influence of construction of the buffer layer and misorientation of the substrate on the electrical properties of In{sup 0.70}Al{sup 0.30}As/In{sup 0.76}Ga{sup 0.24}As/In{sup 0.70}Al{sup 0.30}As quantum wells on a GaAs substrate is studied. The temperature dependences (in the temperature range of 4.2 K < T < 300 K) and field dependences (in magnetic fields as high as 6 T) of the sample resistances are measured. Anisotropy of the resistances in different crystallographic directions is detected; this anisotropy depends on the substrate orientation and construction of the metamorphic buffer layer. In addition, the Hall effect and the Shubnikov–de Haas effect are studied. The Shubnikov–de Haas effect is used to determine the mobilities of electrons separately in several occupied dimensionally quantized subbands in different crystallographic directions. The calculated anisotropy of mobilities is in agreement with experimental data on the anisotropy of the resistances.

  8. ICD-10-CM/PCS: Transferring Knowledge from ICD-9-CM

    PubMed Central

    Sand, Jaime N.; Elison-Bowers, Patt

    2013-01-01

    The transition to ICD-10-CM/PCS has expanded educational opportunities for educators and trainers who are taking on the responsibility of training coders on the new system. Coding education currently faces multiple challenges in the areas of how to train the new workforce, what might be the most efficient method of providing that training, how much retraining of the current workforce with ICD-9-CM training will be required, and how to meet the national implementation deadline of 2014 in the most efficacious manner. This research sought to identify if there was a difference between a group of participants with no knowledge of ICD-9-CM and those with some knowledge of ICD-9-CM in scores on an ICD-10-CM/PCS quiz. Results indicate a difference, supporting the idea of knowledge transfer between the systems and providing additional insight into coding education. PMID:23861677

  9. The cumulative effect of three decades of phosphogypsum amendments in reclaimed marsh soils from SW Spain: (226)Ra, (238)U and Cd contents in soils and tomato fruit.

    PubMed

    Abril, José-María; García-Tenorio, Rafael; Enamorado, Santiago M; Hurtado, M Dolores; Andreu, Luis; Delgado, Antonio

    2008-09-15

    Phosphogypsum (PG), a by-product of the phosphate fertiliser industries, has been applied as soil amendment to reduce Na saturation in soils, as in the reclaimed marsh area from SW Spain, where available PG has a typical fingerprint of 710+/-40 Bq kg(-1) of (226)Ra, 165+/-15 Bq kg(-1) of (238)U and 2.8+/-0.4 mg kg(-1) of Cd. This work was focussed on the cumulative effects of PG amendments on the enrichment of these pollutants in cultivated soils and plants (Lycopersicum esculentum Mill L.) from the area studied, where PG has been applied since 1978 at recommended rates of 20-25 Mg ha(-1) every 2-3 years. A field experiment was conducted over three years to compare activity concentrations of (226)Ra ((214)Pb) and (238)U ((234)Th) in non-reclaimed soils, reclaimed soils with no additional PG application, and reclaimed soils with two additional PG applications. A non-significant effect of two PG amendments (in three years) was observed when compared with non-amended reclaimed plots. Nevertheless, a significant (p<0.05) enrichment of (226)Ra was observed in the surface horizon (0-30 cm) of reclaimed plots relative to deeper horizons and also when compared with the surface horizon of non-reclaimed soil (p<0.05), thereby revealing the cumulative effect of three decades of PG applications. Furthermore, the effect of a continuous application of PG was studied by analysing soils and tomato fruits from six commercial farms with different cumulative rates of PG applied. Cadmium concentrations in tomatoes, which were one order of magnitude higher than those found in tomatoes from other areas in South Spain, were positively correlated (r = 0.917) with (226)Ra-concentration in soils, which can be considered an accurate index of the cumulative PG rate of each farm. PMID:18602676

  10. Detailed modelling of the 21-cm forest

    NASA Astrophysics Data System (ADS)

    Semelin, B.

    2016-01-01

    The 21-cm forest is a promising probe of the Epoch of Reionization. The local state of the intergalactic medium (IGM) is encoded in the spectrum of a background source (radio-loud quasars or gamma-ray burst afterglow) by absorption at the local 21-cm wavelength, resulting in a continuous and fluctuating absorption level. Small-scale structures (filaments and minihaloes) in the IGM are responsible for the strongest absorption features. The absorption can also be modulated on large scales by inhomogeneous heating and Wouthuysen-Field coupling. We present the results from a simulation that attempts to preserve the cosmological environment while resolving some of the small-scale structures (a few kpc resolution in a 50 h-1 Mpc box). The simulation couples the dynamics and the ionizing radiative transfer and includes X-ray and Lyman lines radiative transfer for a detailed physical modelling. As a result we find that soft X-ray self-shielding, Ly α self-shielding and shock heating all have an impact on the predicted values of the 21-cm optical depth of moderately overdense structures like filaments. A correct treatment of the peculiar velocities is also critical. Modelling these processes seems necessary for accurate predictions and can be done only at high enough resolution. As a result, based on our fiducial model, we estimate that LOFAR should be able to detect a few (strong) absorptions features in a frequency range of a few tens of MHz for a 20 mJy source located at z = 10, while the SKA would extract a large fraction of the absorption information for the same source.

  11. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  12. Isotope shifts in methane near 6000/cm

    NASA Technical Reports Server (NTRS)

    Fox, K.; Halsey, G. W.; Jennings, D. E.

    1976-01-01

    Isotope shifts for cleanly resolved vibrational-rotational absorption lines of CH4-12 and CH4-13 were measured by a 5-m focal length Littrow spectrometer in the 6000/cm range. The methane isotopes were held in separate absorption cells: 20 torr of CH4-13 in a 1-m cell, and 5 torr of CH4-12 in a White cell of 4-m optical path length. Measured shifts for the cleanly resolved singlets R(0), R(1), Q(1) and P(1) are summarized in tabular form.

  13. An engineering model 30 cm ion thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; King, H. J.; Schnelker, D. E.

    1973-01-01

    Thruster development at Hughes Research Laboratories and NASA Lewis Research Center has brought the 30-cm mercury bombardment ion thruster to the state of an engineering model. This thruster has been designed to have sufficient internal strength for direct mounting on gimbals, to weigh 7.3 kg, to operate with a corrected overall efficiency of 71%, and to have 10,000 hours lifetime. Subassemblies, such as the ion optical system, isolators, etc., have been upgraded to meet launch qualification standards. This paper presents a summary of the design specifications and performance characteristics which define the interface between the thruster module and the remainder of the propulsion system.

  14. Ecological and Historical Controls on Black Carbon Storage in Hawaiian Grassland Soils

    NASA Astrophysics Data System (ADS)

    Cusack, D. F.; Chadwick, O.; Ladefoged, T.; Vitousek, P.

    2010-12-01

    Black carbon (BC, i.e. charcoal) has long been considered an inert and resistant component of the soil C pool, explaining its persistence in some soils for thousands of years. Because of its recalcitrance relative to other forms of C, small concentrations of BC can be significant as a long-term soil C sink. However, recent evidence suggests that BC is retained unequally across ecosystems. Some studies of climatic gradients found that wetter areas with less frequent fires had larger pools of BC because of incomplete combustion of organic matter. In addition, historical land use may influence long-term BC retention. The principal objectives of this study were to identify patterns and mechanisms driving retention of BC across ecosystem gradients, exploring the influences of climate, soil mineralogy, and historical land use. Soils were collected from precipitation and soil weathering gradients in the Hawaiian Islands. Within the precipitation gradient is an area of known ancient Polynesian agricultural activity. Soils were collected and analyzed for chemical characteristics on and off ancient agricultural fields, and from under archeological walls from 0 - 30 cm. Soils from under walls were used to explore potential inputs of BC associated with the initiation of agriculture at the sites. Chemical analysis (13C NMR) showed significant BC storage across the environmental gradients. Black C represented up to 10 % of total soil carbon in fields, and up to 15 % of C under archaeological walls. Because of larger overall C pools in fields, stocks of BC were larger (4.5 mg BC/g soil) than under walls (2 mg BC/g soil). Radiocarbon dating of macroscopic BC under archeological walls showed a positive correlation between precipitation and BC age (R2 = 0.57, p< 0.05, n = 15), likely reflecting historical patterns in the expansion of Polynesian agricultural activity. While bulk soil C (non-BC) was significantly correlated with precipitation from 800 to 1600 mm MAP (R2 = 0.47, p < 0

  15. Spatial distribution of selected heavy metals and soil fertility status in south-eastern Serbia

    NASA Astrophysics Data System (ADS)

    Saljnikov, E.; Mrvic, V.; Cakmak, D.; Nikoloski, M.; Perovic, V.; Kostic, L.; Brebanovic, B.

    2009-04-01

    Environmental pollution by heavy metals is one of the most powerful factors destroying biosphere components that directly affecting agricultural production quality and therefore health of human and animals. Regional soil contamination by heavy metals occurs mainly in industrial areas and in big cities. However, pollutants can be air-and/or water-transferred to big distances and may accumulated far from industrial zone what makes difficult to distinguish original background concentrations of heavy metals in soil. Our study covers south-eastern part of Serbia and is a part of a big project studying soil fertility and heavy metal contamination all around Serbia. Diverse natural characteristics and heterogeneity of soil cover, as well as, human activity greatly influenced soil fertility parameters, while, diverse geological substrate and human activity determined the level of potential geochemical pollution. There are number of industrial factories functioning from the last century on the studied area. Also, close to studied area, there was a mining in the middle of the last century. About 600 soil samples from surface 0-30 cm were investigated for main soil fertility characteristics (pH, humus, available K and P) and concentrations of selected heavy metals (As, Cd, Cr, Ni and Pb). Soils graded as very acidic cover 46% of the area, which are mainly mountains with acidic parent materials. Content of humus in 41% of soil samples were below 3%. The most of the soils (71%) are weakly supplied available phosphorus. While available potassium in more than 70% is presented in the concentrations enough for good soil quality. So, about 75% of studied area is characterized with unfavorable soil fertility properties (extremly low soil pH, very low content of available P, about half of the area maintained low soil humus) that is located under forests, meadows and pastures. Content of heavy metals on studied area in 80% of sampled soils was below maximum allowed concentrations

  16. Fuel elements of research reactor CM

    SciTech Connect

    Kozlov, A.V.; Morozov, A.V.; Vatulin, A.V.; Ershov, S.A.

    2013-07-01

    In 1961 the CM research reactor was commissioned at the Research Institute of Atomic Reactors (Dimitrovgrad, Russia), it was intended to carry on investigations and the production of transuranium nuclides. The reactor is of a tank type. Original fuel assembly contained plate fuels that were spaced with vanes and corrugated bands. Nickel was used as a cladding material, fuel meat was produced from UO{sub 2} + electrolytic nickel composition. Fuel plates have been replaced by self-spacing cross-shaped dispersion fuels clad in stainless steel. In 2005 the reactor was updated. The purpose of this updating was to increase the quantity of irradiation channels in the reactor core and to improve the neutron balance. The updating was implemented at the expense of 20 % reduction in the quantity of fuel elements in the core which released a space for extra channels and decreased the mass of structural materials in the core. The updated reactor is loaded with modified standard fuel elements with 20 % higher uranium masses. At the same time stainless steel in fuel assembly shrouds was substituted by zirconium alloy. Today in progress are investigations and work to promote the second stage of reactor updating that involve developments of cross-shaped fuel elements having low neutron absorption matrix materials. This article gives an historical account of the design and main technical changes that occurred for the CM reactor since its commissioning.

  17. Redundant Array Configurations for 21 cm Cosmology

    NASA Astrophysics Data System (ADS)

    Dillon, Joshua S.; Parsons, Aaron R.

    2016-08-01

    Realizing the potential of 21 cm tomography to statistically probe the intergalactic medium before and during the Epoch of Reionization requires large telescopes and precise control of systematics. Next-generation telescopes are now being designed and built to meet these challenges, drawing lessons from first-generation experiments that showed the benefits of densely packed, highly redundant arrays—in which the same mode on the sky is sampled by many antenna pairs—for achieving high sensitivity, precise calibration, and robust foreground mitigation. In this work, we focus on the Hydrogen Epoch of Reionization Array (HERA) as an interferometer with a dense, redundant core designed following these lessons to be optimized for 21 cm cosmology. We show how modestly supplementing or modifying a compact design like HERA’s can still deliver high sensitivity while enhancing strategies for calibration and foreground mitigation. In particular, we compare the imaging capability of several array configurations, both instantaneously (to address instrumental and ionospheric effects) and with rotation synthesis (for foreground removal). We also examine the effects that configuration has on calibratability using instantaneous redundancy. We find that improved imaging with sub-aperture sampling via “off-grid” antennas and increased angular resolution via far-flung “outrigger” antennas is possible with a redundantly calibratable array configuration.

  18. 30-cm electron cyclotron plasma generator

    NASA Technical Reports Server (NTRS)

    Goede, Hank

    1987-01-01

    Experimental results on the development of a 30-cm-diam electron cyclotron resonance plasma generator are presented. This plasma source utilizes samarium-cobalt magnets and microwave power at a frequency of 4.9 GHz to produce a uniform plasma with densities of up to 3 x 10 to the 11th/cu cm in a continuous fashion. The plasma generator contains no internal structures, and is thus inherently simple in construction and operation and inherently durable. The generator was operated with two different magnetic geometries. One used the rare-earth magnets arranged in an axial line cusp configuration, which directly showed plasma production taking place near the walls of the generator where the electron temperature was highest but with the plasma density peaking in the central low B-field regions. The second configuration had magnets arranged to form azimuthal line cusps with approximately closed electron drift surfaces; this configuration showed an improved electrical efficiency of about 135 eV/ion.

  19. Combining galaxy and 21-cm surveys

    NASA Astrophysics Data System (ADS)

    Cohn, J. D.; White, Martin; Chang, Tzu-Ching; Holder, Gil; Padmanabhan, Nikhil; Doré, Olivier

    2016-04-01

    Acoustic waves travelling through the early Universe imprint a characteristic scale in the clustering of galaxies, QSOs and intergalactic gas. This scale can be used as a standard ruler to map the expansion history of the Universe, a technique known as baryon acoustic oscillations (BAO). BAO offer a high-precision, low-systematics means of constraining our cosmological model. The statistical power of BAO measurements can be improved if the `smearing' of the acoustic feature by non-linear structure formation is undone in a process known as reconstruction. In this paper, we use low-order Lagrangian perturbation theory to study the ability of 21-cm experiments to perform reconstruction and how augmenting these surveys with galaxy redshift surveys at relatively low number densities can improve performance. We find that the critical number density which must be achieved in order to benefit 21-cm surveys is set by the linear theory power spectrum near its peak, and corresponds to densities achievable by upcoming surveys of emission line galaxies such as eBOSS and DESI. As part of this work, we analyse reconstruction within the framework of Lagrangian perturbation theory with local Lagrangian bias, redshift-space distortions, {k}-dependent noise and anisotropic filtering schemes.

  20. Fission probabilities of 242Am,243Cm , and 244Cm induced by transfer reactions

    NASA Astrophysics Data System (ADS)

    Kessedjian, G.; Jurado, B.; Barreau, G.; Marini, P.; Mathieu, L.; Tsekhanovich, I.; Aiche, M.; Boutoux, G.; Czajkowski, S.; Ducasse, Q.

    2015-04-01

    We have measured the fission probabilities of 242Am,243Cm , and 244Cm induced by the transfer reactions 243Am(3He,4He) ,243Am(3He,t ) , and 243Am(3He,d ) , respectively. The details of the experimental procedure and a rigorous uncertainty analysis, including a correlation matrix, are presented. For 243Cm our data show clear structures well below the fission threshold. To our knowledge, it is the first time that these structures have been observed for this nucleus. We have compared the measured fission probabilities to calculations based on the statistical model to obtain information on the fission barriers of the produced fissioning nuclei.

  1. Aliphatic amines in Antarctic CR2, CM2, and CM1/2 carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Aponte, José C.; McLain, Hannah L.; Dworkin, Jason P.; Elsila, Jamie E.

    2016-09-01

    Meteoritic water-soluble organic compounds provide a unique record of the processes that occurred during the formation of the solar system and the chemistry preceding the origins of life on Earth. We have investigated the molecular distribution, compound-specific δ13C isotopic ratios and enantiomeric compositions of aliphatic monoamines present in the hot acid-water extracts of the carbonaceous chondrites LAP 02342 (CR2), GRA 95229 (CR2), LON 94101 (CM2), LEW 90500 (CM2), and ALH 83100 (CM1/2). Analyses of the concentration of monoamines in these meteorites revealed: (a) the CR2 chondrites studied here contain higher concentrations of monoamines relative to the analyzed CM2 chondrites; (b) the concentration of monoamines decreases with increasing carbon number; and (c) isopropylamine is the most abundant monoamine in these CR2 chondrites, while methylamine is the most abundant amine species in these CM2 and CM1/2 chondrites. The δ13C values of monoamines in CR2 chondrite do not correlate with the number of carbon atoms; however, in CM2 and CM1/2 chondrites, the 13C enrichment decreases with increasing monoamine carbon number. The δ13C values of methylamine in CR2 chondrites ranged from -1 to +10‰, while in CM2 and CM1/2 chondrites the δ13C values of methylamine ranged from +41 to +59‰. We also observed racemic compositions of sec-butylamine, 3-methyl-2-butylamine, and sec-pentylamine in the studied carbonaceous chondrites. Additionally, we compared the abundance and δ13C isotopic composition of monoamines to those of their structurally related amino acids. We found that monoamines are less abundant than amino acids in CR2 chondrites, with the opposite being true in CM2 and CM1/2 chondrites. We used these collective data to evaluate different primordial synthetic pathways for monoamines in carbonaceous chondrites and to understand the potential common origins these molecules may share with meteoritic amino acids.

  2. Influence of land use on soil organic matter

    NASA Astrophysics Data System (ADS)

    Rogeon, H.; Lemée, L.; Chabbi, A.; Ambles, A.

    2009-04-01

    Soil organic matter (SOM) is actually of great environmental interest as the amount of organic matter stored in soils represents one of the largest reservoirs of organic carbon on the global scale [1]. Indeed, soil carbon storage capacity represents 1500 to 2000 Gt for the first meter depth, which is twice the concentration of atmospheric CO2 [2]. Furthermore, human activities, such as deforestation (which represents a flux of 1.3 Gt C/year), contribute to the increase in atmospheric CO2 concentration for about one percent a year [3]. Therefore, carbon dioxide sequestration in plant and carbon storage in soil and biomass could be considered as a complementary solution against climate change. The stock of carbon in soils is greatly influenced by land use (ca 70 Gt for a forest soil or a grassland against 40 Gt for an arable land). Furthermore the molecular composition of SOM should be also influenced by vegetation. In this context, four horizons taken between 0-120 cm from the same profile of a soil under grassland and forest located in the vicinity of Poitiers (INRA Lusignan, ORE Prairie) were compared. For the surface horizon, the study is improved with the results from the cultivated soil from INRA Versailles. Soil organic matter was characterized using IR spectroscopy, elemental analysis and thermal analysis. Granulometric fractionation into sand (50-2000 μm), silt (2-50 μm) and clay (<2 μm) was conducted. The organic matter associated with the mineral fractions was thus characterized using thermochemolysis coupled with gas chromatography and mass spectrometry (Py-GC/MS). The total lipidic fractions were extracted with CH2Cl2/MeOH using an accelerated solvent extraction (ASE). In the three soils, lipids are concentrated into the superficial horizon (0-30 cm) which indicates a low mobilisation. Lipids from the superficial horizon are more abundant for the arable soil (1010 ppm) than for the two other (400 ppm). Lipids from the forest and the grassland were

  3. The role of rock fragments in soils hydric properties

    NASA Astrophysics Data System (ADS)

    Tetegan, Marion; Cousin, Isabelle; Bouthier, Alain; Nicoullaud, Bernard

    2010-05-01

    Stony soils contain rock fragments, called stones, which limits some tillage operations. These soils often thin cover about 30% of the surface soils of Western Europe and 60% in Mediterranean areas. Though stony soils are widely spread and create problems to agriculture production, they have been little studied. As stones characterization is difficult, the stony phase is often neglected in the characterization of the properties of stony soils. However, some authors have demonstrated that the rock fragments could modify the physical, chemical and hydrodynamic properties of soils, and affect the behaviour and characteristics of agricultural soils. Indeed, the stony phase may participate in the water supply of crops and change the storage capacity of soil water. All these previous studies suggest some water transfers between the rock fragments and fine earth in soil. The objective of this work was to study the contribution of stony phase to the soil hydric properties by characterising the structure and the water retention capacity of rock fragments from different types of stony soils. The stones were sampled in the cultivated horizon (0 - 30 cm) of different types of stony soils in the Central part of France. Only the pebble fraction (2 cm < stone diameter < 5 cm) was studied. Most of the stones were collected when the soil was at field capacity. The pebbles were sampled in soils developed over sedimentary rocks and were of the following types: gaize, chalk, chert, flint, and limestone. The structure of each dry pebble was characterized by measurements of bulk density and density of solid, and by calculation of the void ratio of the sample. The porosity, but also bulk density and void ratio varied according to the type of stone, and within a single type of stone, and especially for the limestones. The hydric properties were determined by measurements of gravimetric water content when the pebbles were at saturation or after they were equilibrated at -100 hPa and -15000

  4. Overcoming the Challenges of 21cm Cosmology

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    The highly-redshifted 21cm line of neutral hydrogen is one of the most promising and unique probes of cosmology for the next decade and beyond. The past few years have seen a number of dedicated experiments targeting the 21cm signal from the Epoch of Reionization (EoR) begin operation, including the LOw-Frequency ARray (LOFAR), the Murchison Widefield Array (MWA), and the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER). For these experiments to yield cosmological results, they require new calibration and analysis algorithms which will need to achieve unprecedented levels of separation between the 21cm signal and contaminating foreground emission. Although much work has been spent developing these algorithms over the past decade, their success or failure will ultimately depend on their ability to overcome the complications associated with real-world systems and their inherent complications. The work in this dissertation is closely tied to the late-stage commissioning and early observations with PAPER. The first two chapters focus on developing calibration algorithms to overcome unique problems arising in the PAPER system. To test these algorithms, I rely on not only simulations, but on commissioning observations, ultimately tying the success of the algorithm to its performance on actual, celestial data. The first algorithm works to correct gain-drifts in the PAPER system caused by the heating and cooling of various components (the amplifiers and above ground co-axial cables, in particular). It is shown that a simple measurement of the ambient temperature can remove ˜ 10% gain fluctuations in the observed brightness of calibrator sources. This result is highly encouraging for the ability of PAPER to remove a potentially dominant systematic in its power spectrum and cataloging measurements without resorting to a complicated system overhaul. The second new algorithm developed in this dissertation solves a major calibration challenge not

  5. The 30-cm ion thruster power processor

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hopper, D. J.

    1978-01-01

    A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

  6. 70-cm radar observations of 433 Eros

    NASA Technical Reports Server (NTRS)

    Campbell, D. B.; Pettengill, G. H.; Shapiro, I. I.

    1976-01-01

    Radar observations of 433 Eros were made at the Arecibo Observatory using a wavelength of 70 cm during the close approach of Eros to earth in mid-January, 1975. A peak radar cross section of plus or minus 15 sq km was observed. The spectral broadening obtained was approximately 30 Hz, which is consistent with a value of 16 km for the maximum radius of the asteroid. The surface of Eros appears to be relatively rough at the scale of a wavelength as compared to the surfaces of the terrestrial planets and the moon. The composition of the surface is not well determined, except that it cannot be a highly conducting metal. A single measurement each of round-trip echo times delay and Doppler shift was made.

  7. NASA 30 Cm Ion Thruster Development Status

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Rawlin, Vincent K.; Kussmaul, Michael T.

    1995-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest and it is an element of the NASA Solar Electric Propulsion Technology Applications Readiness (NSTAR) program established to validate ion propulsion for space flight applications. The thruster has been developed to an engineering model level and it incorporates innovations in design, materials, and fabrication techniques compared to those employed to conventional ion thrusters. The performance of both functional and engineering model thrusters has been assessed including thrust stand measurements, over an input power range of 0.5-2.3 kW. Attributes of the engineering model thruster include an overall mass of 6.4 kg, and an efficiency of 65 percent and thrust of 93 mN at 2.3 kW input power. This paper discusses the design, performance, and lifetime expectations of the functional and engineering model thrusters under development at NASA.

  8. Soil Water Content Sensor Response to Organic Matter Content under Laboratory Conditions.

    PubMed

    Fares, Ali; Awal, Ripendra; Bayabil, Haimanote K

    2016-01-01

    Studies show that the performance of soil water content monitoring (SWCM) sensors is affected by soil physical and chemical properties. However, the effect of organic matter on SWCM sensor responses remains less understood. Therefore, the objectives of this study are to (i) assess the effect of organic matter on the accuracy and precision of SWCM sensors using a commercially available soil water content monitoring sensor; and (ii) account for the organic matter effect on the sensor's accuracy. Sand columns with seven rates of oven-dried sawdust (2%, 4%, 6%, 8%, 10%, 12% and 18% v/v, used as an organic matter amendment), thoroughly mixed with quartz sand, and a control without sawdust were prepared by packing quartz sand in two-liter glass containers. Sand was purposely chosen because of the absence of any organic matter or salinity, and also because sand has a relatively low cation exchange capacity that will not interfere with the treatment effect of the current work. Sensor readings (raw counts) were monitored at seven water content levels (0, 0.02, 0.04, 0.08, 0.12, 0.18, 0.24, and 0.30 cm³ cm(-3)) by uniformly adding the corresponding volumes of deionized water in addition to the oven-dry one. Sensor readings were significantly (p < 0.05) affected by the organic matter level and water content. Sensor readings were strongly correlated with the organic matter level (R² = 0.92). In addition, the default calibration equation underestimated the water content readings at the lower water content range (<0.05 cm³ cm(-3)), while it overestimated the water content at the higher water content range (>0.05 cm³ cm(-3)). A new polynomial calibration equation that uses raw count and organic matter content as covariates improved the accuracy of the sensor (RMSE = 0.01 cm³ cm(-3)). Overall, findings of this study highlight the need to account for the effect of soil organic matter content to improve the accuracy and precision of the tested sensor under different soils and

  9. Geo-pedological control of soil organic carbon and nitrogen stocks at the landscape scale

    NASA Astrophysics Data System (ADS)

    Barré, Pierre; Durand, Hermine; Chenu, Claire; Meunier, Patrick; Montagne, David; Castel, Géraldine; Billiou, Daniel; Cécillon, Lauric

    2015-04-01

    Geo-pedology, here defined as soil type (or Reference Soil Group) and parent material, can have a major impact on ecosystem (vegetation and soil) functioning. Geo-pedology can therefore deeply influence soil organic matter (SOM) stock. Nonetheless, the effect of geo-pedology on soil organic C (SOC) and N stocks has seldom been investigated. Indeed, factors known to influence SOM stocks such as land use and climate frequently co-vary with geo-pedology, so that testing the influence on SOM stocks of the factor "geo-pedology" alone is challenging. In this work, we studied SOM stocks of forest and cropland soils in a small landscape (17 km²) of the Paris basin (AgroParisTech domain, Thiverval-Grignon, France). We collected soil samples (0-30 cm) in 50 forest and cropland plots, located in five geo-pedological contexts: Luvisols developed on loess deposit, Cambisols developed on hard limestone, Cambisols developed on shelly limestone, Cambisols developed on chalk and Cambisols developed on calcareous clay deposits. We then determined SOM stocks (organic C and total N) and SOM distribution across different particle size fractions (coarse sand, fine sand and silt-clay). As expected, SOC stocks were much higher in forests (~ 83 tC ha-1) than in cultivated soils (~ 49 tC ha-1). Interestingly, Cambisols had higher SOC stocks than Luvisols (69 vs 56 tC ha-1) and the difference between SOC stocks in forest and cultivated soils was much higher for Cambisols compared to Luvisols. Within Cambisols, parent material did not influence SOC stocks but the interaction between parent material and land use was significant, indicating that the effect of land use on SOC stocks was modulated by parent material. Similar trends were observed for soil N stocks. Conversely, soil type and parent material did not control SOM distribution in soil size fractions, while forest soils showed a higher distribution of SOC and N in the sand-size fraction than cropland soils. Overall, our study evidenced

  10. Spatial assessment of soil salinity in the Harran Plain using multiple kriging techniques.

    PubMed

    Bilgili, Ali V

    2013-01-01

    The Harran Plain is located in the southeastern part of Turkey and has recently been developed for irrigation agriculture. It already faces soil salinity problems causing major yield losses. Management of the problem is hindered by the lack of information on the extent and geography of the salinization problem. A survey was carried out to delineate the spatial distribution of salt-affected areas by randomly selecting 140 locations that were sampled at two depths (0 to 30 and 30 to 60 cm) and analyzed for soil salinity variables: soil electrical conductivity (EC), soluble cations (Ca(2+,) Mg(2+), Na(+), and K(+)), soluble anions (SO (4) (2-) , Cl(-)), exchangeable Na(+) (me 100 g(-1)) and exchangeable sodium percentage. Terrain attributes (slope, topographical wetness index) were extracted from the digital elevation model of the study area. Variogram analyses after log transformation and ordinary kriging (OK) were applied to map spatial patterns of soil salinity variables. Multivariate geostatistical methods-regression kriging (RK) and kriging with external drift (KED)-were used using elevation and soil electrical conductivity data as covariates. Performances of the three estimation methods (OK, RK, and KED) were compared using independent validation samples randomly selected from the main dataset. Soils were categorized into salinity classes using disjunctive kriging (DK) and ArcGIS, and classification accuracy was tested using the kappa statistic. Results showed that soil salinity variables all have skewed distribution and are poorly correlated with terrain indices but have strong correlations among each other. Up to 65 % improvement was obtained in the estimations of soil salinity variables using hybrid methods over OK with the best estimations obtained with RK using EC(0-30) as covariate. DK-ArcGIS successfully classified soil samples into different salinity groups with overall accuracy of 75 % and kappa of 0.55 (p < 0.001). PMID:22415846

  11. Evaluation of Argonne 9-cm and 10-cm Annular Centrifugal Contactors for SHINE Solution Processing

    SciTech Connect

    Wardle, Kent E.; Pereira, Candido; Vandegrift, George

    2015-02-01

    Work is in progress to evaluate the SHINE Medical Technologies process for producing Mo-99 for medical use from the fission of dissolved low-enriched uranium (LEU). This report addresses the use of Argonne annular centrifugal contactors for periodic treatment of the process solution. In a letter report from FY 2013, Pereira and Vandegrift compared the throughput and physical footprint for the two contactor options available from CINC Industries: the V-02 and V-05, which have rotor diameters of 5 cm and 12.7 cm, respectively. They suggested that an intermediately sized “Goldilocks” contactor might provide a better balance between throughput and footprint to meet the processing needs for the uranium extraction (UREX) processing of the SHINE solution to remove undesired fission products. Included with the submission of this letter report are the assembly drawings for two Argonne-design contactors that are in this intermediate range—9-cm and 10-cm rotors, respectively. The 9-cm contactor (drawing number CE-D6973A, stamped February 15, 1978) was designed as a single-stage unit and built and tested in the late 1970s along with other size units, both smaller and larger. In subsequent years, a significant effort to developed annular centrifugal contactors was undertaken to support work at Hanford implementing the transuranic extraction (TRUEX) process. These contactors had a 10-cm rotor diameter and were fully designed as multistage units with four stages per assembly (drawing number CMT-E1104, stamped March 14, 1990). From a technology readiness perspective, these 10-cm units are much farther ahead in the design progression and, therefore, would require significantly less re-working to make them ready for UREX deployment. Additionally, the overall maximum throughput of ~12 L/min is similar to that of the 9-cm unit (10 L/min), and the former could be efficiently operated over much of the same range of throughput. As a result, only the 10-cm units are considered here

  12. Spatial variation in soil phosphomonoesterase in irrigated and dry farmlands

    NASA Astrophysics Data System (ADS)

    Sinegani, A. A. S.; Hossainpour, A.; Nazarizadeh, F.

    2006-05-01

    Spatial variation in the content of acid and alkaline phosphatase was surveyed on two farmlands. Two adjacent plots, one irrigated and cultivated and the other nonirrigated and cultivated, were marked on a 300-m-long transect with 10-m spacing. Soil samples were collected at the depths of 0-30 and 30-60 cm and were then analyzed for acid and alkaline phosphatase and other soil parameters. The analytical results were then subjected to classical statistical and geostatistical analysis. The results showed that the correlation coefficients of the phosphatase and clay, the silt, the sand, the mean weight diameter, the geometric mean diameter, the equivalent CaCO3, the pH, the electrical conductivity, the organic carbon, the respiration, the Olsen available phosphorus, and the vesicular arbuscular mycorrhizae (VAM) spore numbers of the soils in the transect studied were highly significant. In both layers of the irrigated farmland, the coefficients of the variation of the acid phosphatase were relatively high and the coefficients of the variation of the alkaline phosphatase were relatively low compared to those of the dry farmland. Although the acid and alkaline phosphatase in the topsoil and subsoil of the farmlands exhibited a spatial dependence at the sampled scale, the stability of the spatial structures were markedly low.

  13. A new data set for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

    NASA Astrophysics Data System (ADS)

    Hugelius, G.; Bockheim, J. G.; Camill, P.; Elberling, B.; Grosse, G.; Harden, J. W.; Johnson, K.; Jorgenson, T.; Koven, C. D.; Kuhry, P.; Michaelson, G.; Mishra, U.; Palmtag, J.; Ping, C.-L.; O'Donnell, J.; Schirrmeister, L.; Schuur, E. A. G.; Sheng, Y.; Smith, L. C.; Strauss, J.; Yu, Z.

    2013-12-01

    High-latitude terrestrial ecosystems are key components in the global carbon cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (a total area of 18.7 × 106 km2). The NCSCD is a geographical information system (GIS) data set that has been constructed using harmonized regional soil classification maps together with pedon data from the northern permafrost region. Previously, the NCSCD has been used to calculate SOC storage to the reference depths 0-30 cm and 0-100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100-300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this deeper SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon data set for SOC storage (kg C m-2) in deep soils of the northern circumpolar permafrost regions, with separate data sets for the 100-200 cm (524 pedons) and 200-300 cm (356 pedons) depth ranges. These pedons have been grouped into the North American and Eurasian sectors and the mean SOC storage for different soil taxa (subdivided into Gelisols including the sub-orders Histels, Turbels, Orthels, permafrost-free Histosols, and permafrost-free mineral soil orders) has been added to the updated NCSCDv2. The updated version of the data set is freely available online in different file formats and spatial resolutions that enable spatially explicit applications in GIS mapping and terrestrial ecosystem models. While this newly compiled data set adds to our knowledge of SOC in the 100-300 cm depth range, it also reveals that large uncertainties remain. Identified data gaps include spatial coverage of deep (> 100 cm) pedons in many regions as well as the spatial extent of areas with thin

  14. Effects of Revegetation on Soil Organic Carbon Storage and Erosion-Induced Carbon Loss under Extreme Rainstorms in the Hill and Gully Region of the Loess Plateau

    PubMed Central

    Li, Yujin; Jiao, Juying; Wang, Zhijie; Cao, Binting; Wei, Yanhong; Hu, Shu

    2016-01-01

    Background: The Loess Plateau, an ecologically vulnerable region, has long been suffering from serious soil erosion. Revegetation has been implemented to control soil erosion and improve ecosystems in the Loess Plateau region through a series of ecological recovery programs. However, the increasing atmospheric CO2 as a result of human intervention is affecting the climate by global warming, resulting in the greater frequency and intensity of extreme weather events, such as storms that may weaken the effectiveness of revegetation and cause severe soil erosion. Most research to date has evaluated the effectiveness of revegetation on soil properties and soil erosion of different land use or vegetation types. Here, we study the effect of revegetation on soil organic carbon (SOC) storage and erosion-induced carbon loss related to different plant communities, particularly under extreme rainstorm events. Materials and methods: The erosion-pin method was used to quantify soil erosion, and soil samples were taken at soil depths of 0–5 cm, 5–10 cm and 10–20 cm to determine the SOC content for 13 typical hillside revegetation communities in the year of 2013, which had the highest rainfall with broad range, long duration and high intensity since 1945, in the Yanhe watershed. Results and discussion: The SOC concentrations of all plant communities increased with soil depth when compared with slope cropland, and significant increases (p < 0.05) were observed for most shrub and forest communities, particularly for natural ones. Taking the natural secondary forest community as reference (i.e., soil loss and SOC loss were both 1.0), the relative soil loss and SOC loss of the other 12 plant communities in 2013 ranged from 1.5 to 9.4 and 0.30 to 1.73, respectively. Natural shrub and forest communities showed greater resistance to rainstorm erosion than grassland communities. The natural grassland communities with lower SOC content produced lower SOC loss even with higher soil

  15. Detecting the 21 cm forest in the 21 cm power spectrum

    NASA Astrophysics Data System (ADS)

    Ewall-Wice, Aaron; Dillon, Joshua S.; Mesinger, Andrei; Hewitt, Jacqueline

    2014-07-01

    We describe a new technique for constraining the radio-loud population of active galactic nuclei at high redshift by measuring the imprint of 21 cm spectral absorption features (the 21 cm forest) on the 21 cm power spectrum. Using semi-numerical simulations of the intergalactic medium and a semi-empirical source population, we show that the 21 cm forest dominates a distinctive region of k-space, k ≳ 0.5 Mpc- 1. By simulating foregrounds and noise for current and potential radio arrays, we find that a next-generation instrument with a collecting area of the order of ˜ 0.1 km2 (such as the Hydrogen Epoch of Reionization Array) may separately constrain the X-ray heating history at large spatial scales and radio-loud active galactic nuclei of the model we study at small ones. We extrapolate our detectability predictions for a single radio-loud active galactic nuclei population to arbitrary source scenarios by analytically relating the 21 cm forest power spectrum to the optical depth power spectrum and an integral over the radio luminosity function.

  16. Engineering model 8-cm thruster subsystem

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J.; Hopper, D. J.; Williamson, W. S.; Dulgeroff, C. R.; Collett, C. R.

    1978-01-01

    An Engineering Model (EM) 8 cm Ion Thruster Propulsion Subsystem was developed for operation at a thrust level 5 mN (1.1 mlb) at a specific impulse 1 sub sp = 2667 sec with a total system input power P sub in = 165 W. The system dry mass is 15 kg with a mercury-propellant-reservoir capacity of 8.75 kg permitting uninterrupted operation for about 12,500 hr. The subsystem can be started from a dormant condition in a time less than or equal to 15 min. The thruster has a design lifetime of 20,000 hr with 10,000 startup cycles. A gimbal unit is included to provide a thrust vector deflection capability of + or - 10 degrees in any direction from the zero position. The EM subsystem development program included thruster optimization, power-supply circuit optimization and flight packaging, subsystem integration, and subsystem acceptance testing including a cyclic test of the total propulsion package.

  17. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  18. Effect of minimum tillage and mulching on maize ( Zea mays L.) yield and water content of clayey and sandy soils

    NASA Astrophysics Data System (ADS)

    Mupangwa, Walter; Twomlow, Steve; Walker, Sue; Hove, Lewis

    Rainfed smallholder agriculture in semi-arid areas of southern Africa is subject to numerous constraints. These include low rainfall with high spatial and temporal variability, and significant loss of soil water through evaporation. An experiment was established at Matopos Research Station, Zimbabwe, to determine the effect of mulching and minimum tillage on maize ( Zea mays L.) yield and soil water content. The experiment was run for two years at two sites: clay (Matopos Research Station fields) and sand (Lucydale fields) soils, in a 7 × 3 factorial combination of mulch rates (0, 0.5, 1, 2, 4, 8 and 10 t ha -1) and tillage methods (planting basins, ripper tine and conventional plough). Each treatment was replicated three times at each site in a split plot design. Maize residue was applied as mulch before tillage operations. Two maize varieties, a hybrid (SC 403) and an open pollinated variety (ZM 421), were planted. Maize yield and soil water content (0-30 and 30-60 cm depth) were measured under each treatment. On both soil types, neither mulching nor tillage method had a significant effect on maize grain yield. Tillage methods significantly influenced stover production with planting basins giving the highest stover yield (1.1 t ha -1) on sandy soil and conventional ploughing giving 3.6 t ha -1 on clay soil during the first season. The three tillage methods had no significant effect on seasonal soil water content, although planting basins collected more rainwater during the first half of the cropping period. Mulching improved soil water content in both soil types with maximum benefits observed at 4 t ha -1 of mulch. We conclude that, in the short term, minimum tillage on its own, or in combination with mulching, performs as well as the farmers’ traditional practices of overall ploughing.

  19. A sub-cm micromachined electron microscope

    NASA Technical Reports Server (NTRS)

    Feinerman, A. D.; Crewe, D. A.; Perng, D. C.; Shoaf, S. E.; Crewe, A. V.

    1993-01-01

    A new approach for fabricating macroscopic (approximately 10x10x10 mm(exp 3)) structures with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create four orthogonal v-grooves and an aperture on each 10x12 mm die. Precision 308 micron optical fibers are sandwiched between the die to align the v-grooves. The fiber is then anodically bonded to the die above and below it. This procedure is repeated to create thick structures and a stack of 5 or 6 die will be used to create a miniature scanning electron microscope (MSEM). Two die in the structure will have a segmented electrode to deflect the beam and correct for astigmatism. The entire structure is UHV compatible. The performance of an SEM improves as its length is reduced and a sub-cm 2 keV MSEM with a field emission source should have approximately 1 nm resolution. A low voltage high resolution MSEM would be useful for the examination of biological specimens and semiconductors with a minimum of damage. The first MSEM will be tested with existing 6 micron thermionic sources. In the future a micromachined field emission source will be used. The stacking technology presented in this paper can produce an array of MSEMs 1 to 30 mm in length with a 1 mm or larger period. A key question being addressed by this research is the optimum size for a low voltage MSEM which will be determined by the required spatial resolution, field of view, and working distance.

  20. Long-term Effect of Pig Slurry Application on Soil Carbon Storage, Quality and Yield Sustainability in Murcia Region, Spain

    NASA Astrophysics Data System (ADS)

    Büyükkılıç Yanardaǧ, Asuman

    2013-04-01

    Sustainability of agriculture is now a major global concern, especially since the 1980s. Soil organic matter is very important in the proper functions of the soil, which is also a good indicator of soil quality. This is due to its influence on many of the chemical, physical, and biological processes that control the capacity of a soil to perform properly. Understanding of nutrient supply through organic matter mineralization in agricultural systems is essential for maintaining long-term quality and productivity. The composition of pig manure will have a profound impact on soil properties, quality and crop yield when used in agriculture. We studied the effects of pig slurry (PS) application as an organic fertilizer, trying to determine the optimum amount that can be added to the soil, and the effect on soil properties, quality, and productivity. We applied 3 different doses on silty loam soils: Single (D1), Double (D2), Triple (D3) and unfertilized plots (C) served as controls. Samples were collected at two different levels, surface (0-30 cm) and subsurface (30-60 cm). D1 application dose, which is the agronomic rate of N-requirement (170 kg N/ha/yr) (European Directive 91/676/CEE), is very appropriate in term of sustainable agriculture and also can improve physical, chemical and biological soil properties. Therefore that the long-term use of PS with low dose may necessarily enhance soil quality in the long term. There are many factors to be considered when attempting to assess the overall net impact of a management practice on productivity. Additions of pig manure to soils at agronomic rates (170 kg N ha-1 yr-1) to match crop nutrient requirements are expected to have a positive impact on soil productivity. Therefore, the benefits from the use of application depend on the management of PS, carbon and environmental quality. However, PS have high micronutrient contents, and for this reason the application of high doses can pollute soils and damage human, animal and

  1. Soil carbon sequestration and land use change associated with biofuel production: Empirical evidence

    SciTech Connect

    Qin, Zhangcai; Dunn, Jennifer B.; Kwon, Hoyoung; Mueller, Steffen; Wander, Michelle M.

    2016-01-01

    Soil organic carbon (SOC) change can be a major impact of land use change (LUC) associated with biofuel feedstock production. By collecting and analyzing data from worldwide field observations with major LUCs from cropland, grassland and forest to lands producing biofuel crops (i.e., corn, switchgrass, Miscanthus, poplar and willow), we were able to estimate SOC response ratios and sequestration rates and evaluate the effects of soil depth and time scale on SOC change. Both the amount and rate of SOC change were highly dependent on the specific land transition. Irrespective of soil depth or time horizon, cropland conversions resulted in an overall SOC gain of 6-14% relative to initial SOC level, while conversion from grassland or forest to corn (without residue removal) or poplar caused significant carbon loss (9-35%). No significant SOC changes were observed in land converted from grasslands or forests to switchgrass, Miscanthus or willow. The SOC response ratios were similar in both 0-30 and 0-100 cm soil depths in most cases, suggesting SOC changes in deep soil and that use of top soil only for SOC accounting in biofuel life cycle analysis (LCA) might underestimate total SOC changes. Soil carbon sequestration rates varied greatly among studies and land transition types. Generally, the rates of SOC change tended to be the greatest during the 10 years following land conversion, and had declined to approach 0 within about 20 years for most LUCs. Observed trends in SOC change were generally consistent with previous reports. Soil depth and duration of study significantly influence SOC change rates and so should be considered in carbon emission accounting in biofuel LCA. High uncertainty remains for many perennial systems, field trials and modeling efforts are needed to determine the site- and system-specific rates and direction of change associated with their production.

  2. Soil property effects on wind erosion of organic soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (>20%) in half or more of the upper 80 cm. Forty four states have a total of 21 million ha of histosols in the United States. These soils, when intensively cropped, are subject to wind erosion r...

  3. Soil Property Effects on Wind Erosion of Organic Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (>20%) in half or more of the upper 80 cm. Forty four states have a total of 21 million ha of histosols in the United States. These soils, when intensively cropped, are subject to wind erosion r...

  4. National-Scale Changes in Soil Profile C and N in New Zealand Pastures are Determined by Land Use

    NASA Astrophysics Data System (ADS)

    Schipper, L. A.; Parfitt, R.; Ross, C.; Baisden, W. T.; Claydon, J.; Fraser, S.

    2010-12-01

    Grazed pasture is New Zealand’s predominant agricultural land-use and has been relatively recently developed from forest and native grasslands/shrub communities. From the 1850s onwards, land was cleared and exotic pastures established. Phosphorus fertilizer was increasingly used after 1950 which accelerated N fixation by clover. In the last two decades N fertilizers have been used, and grazing intensity has increased, thus affecting soil C and N. Re-sampling of 31 New Zealand soil profiles under grazed pasture measured surprisingly large losses of C and N over the last 2-3 decades (Schipper et al., 2007 Global Change Biology 13:1138-1144). These profiles were predominantly on the most intensively grazed flat land. We extended this re-sampling to 83 profiles (to 90 cm depth), to investigate whether changes in soil C and N stocks also occurred in less intensively managed pasture. Archived soils samples were analysed for total soil C and N alongside the newly collected samples. Intact cores were collected to determine bulk density through the profile. Over an average of 27 years, soils (0-30 cm) in flat dairy pastures significantly lost 0.73±0.16 Mg C ha-1y-1 and 57±16 kg N ha-1y-1 while we observed no change in soil C or N in flat pasture grazed by “dry stock” (e.g., sheep, beef), or in grazed tussock grasslands. Grazed hill country soils (0-30 cm) gained 0.52±0.18 Mg C ha-1y-1 and 66±18 kg N ha-1y-1. The losses of C and N were strongly correlated and C:N ratio has generally declined suggesting soils are becoming N saturated. Losses and gains also occurred in soil layers below 30 cm demonstrating that organic matter throughout the profile was responding to land use. The losses under dairying may be due to greater grazing pressure, fertilizer inputs and exports of C and N. There is evidence that grazing pressure reduces inputs of C below ground, reduces soil microbial C, and that dairy cow urine can mobilise C and N. Gains in hill country pastures may be due

  5. Reclamation of soils influenced by coal mining in Southern European Russia

    NASA Astrophysics Data System (ADS)

    Alekseenko, Vladimir; Bech, Jaume; Alekseenko, Alexey; Shvydkaya, Natalya; Roca, Núria

    2016-04-01

    In the recent decades, the concentrations of metals have increased in such media of biosphere as atmosphere, hydrosphere, pedosphere. The greatest geochemical changes have occurred in soils, which are the deposing medium where the high concentrations of metals are saved for years after their direct human use. Mining sites and beneficiation zones are the areas of the highest concentrations of metals in soils. Coal mining areas in the European part of Russia (Rostov region) were selected for a detailed consideration. Soil samples were taken from the uppermost soil horizons: layer of 0-30 cm. The soil samples were analysed for gross concentrations of Cu, Zn, Pb, Ag, Sn, Mo, Ba, Co, Ni, Mn, Ti, V, Cr, Ga, P, Li, Sr, Y, Yb, Nb, Sc, and Zr, using emission spectral analysis. All ordinary analyses were carried out in the certified and accredited laboratory. The external control was conducted by the X-ray fluorescence, gravimetric, and neutron activation analyses. Calculation of random and systematic errors showed high analyses repeatability and correctness. Several cases of self-purification of soils and restoration of landscapes were discussed. The way of remediation through the flooding of mining sites with water was investigated as well as filling of natural relief depressions with soils and dumps. The process of Technosols remediation at the sites occupied by tailings of waste heaps was considered separately. In conclusion: 1. The dominant contemporary way of remediation in Southern European Russia does not prevent the spread of metals through the decades. The modern underground coal mining leads to the destruction of soils in the area directly occupied by wastes and by rock dumps located nearby. 2. Soils have not formed yet as a result of self-restoration at the waste heaps at the age of 50 years, spontaneously combusted decades ago. The vegetation formed during this time virtually eliminates the occurrence of any significant soil-forming process. The ponds formed by

  6. Influence of Pig Slurry on Microbial and Biochemical Characteristics of Soil in Albacete Region, SE Spain

    NASA Astrophysics Data System (ADS)

    Halil Yanardaǧ, Ibrahim

    2013-04-01

    , whereas, black and soluble C was decreased with PS addition. There may have been a transient positive effect of the RPS treatments on the soil biochemical parameters. However, the effect could not be detected because of less labile C content during the experiment. The beneficial effects of the PS additions were less pronounced in the 0-30 cm. soil layer. In this monoculture barley production system and under these Mediterranean climate conditions, applications of TPS should be avoided, so they were associated with a decline in microbial counts and a leveling of almost all the enzymatic activities and microbial biomass C. Keywords: Pig slurry, Microbial biomass C, soluble C, black C, β-Glucosidase, β-galactosidase and Arylesterase enzyme activities.

  7. PROCESS OF PRODUCING Cm$sup 244$ AND Cm$sup 24$$sup 5$

    DOEpatents

    Manning, W.M.; Studier, M.H.; Diamond, H.; Fields, P.R.

    1958-11-01

    A process is presented for producing Cm and Cm/sup 245/. The first step of the process consists in subjecting Pu/sup 2339/ to a high neutron flux and subsequently dissolving the irradiated material in HCl. The plutonium is then oxidized to at least the tetravalent state and the solution is contacted with an anion exchange resin, causing the plutonium values to be absorbed while the fission products and transplutonium elements remain in the effluent solution. The effluent solution is then contacted with a cation exchange resin causing the transplutonium, values to be absorbed while the fission products remain in solution. The cation exchange resin is then contacted with an aqueous citrate solution and tbe transplutonium elements are thereby differentially eluted in order of decreasing atomic weight, allowing collection of the desired fractions.

  8. Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material

    USGS Publications Warehouse

    Steven, Blaire; Gallegos-Graves, La Verne; Belnap, Jayne; Kuske, Cheryl R.

    2013-01-01

    Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0–1 cm; below-crust soils, 2–5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances.

  9. Dryland soil microbial communities display spatial biogeographic patterns associated with soil depth and soil parent material.

    PubMed

    Steven, Blaire; Gallegos-Graves, La Verne; Belnap, Jayne; Kuske, Cheryl R

    2013-10-01

    Biological soil crusts (biocrusts) are common to drylands worldwide. We employed replicated, spatially nested sampling and 16S rRNA gene sequencing to describe the soil microbial communities in three soils derived from different parent material (sandstone, shale, and gypsum). For each soil type, two depths (biocrusts, 0-1 cm; below-crust soils, 2-5 cm) and two horizontal spatial scales (15 cm and 5 m) were sampled. In all three soils, Cyanobacteria and Proteobacteria demonstrated significantly higher relative abundance in the biocrusts, while Chloroflexi and Archaea were significantly enriched in the below-crust soils. Biomass and diversity of the communities in biocrusts or below-crust soils did not differ with soil type. However, biocrusts on gypsum soil harbored significantly larger populations of Actinobacteria and Proteobacteria and lower populations of Cyanobacteria. Numerically dominant operational taxonomic units (OTU; 97% sequence identity) in the biocrusts were conserved across the soil types, whereas two dominant OTUs in the below-crust sand and shale soils were not identified in the gypsum soil. The uniformity with which small-scale vertical community differences are maintained across larger horizontal spatial scales and soil types is a feature of dryland ecosystems that should be considered when designing management plans and determining the response of biocrusts to environmental disturbances. PMID:23621290

  10. Study of temperature-dependent Raman spectroscopy and electrical properties in [001]-oriented 0.35Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.30PbTiO3-Mn single crystals

    NASA Astrophysics Data System (ADS)

    Liu, Xing; Fang, Bijun; Deng, Ji; Yan, Hong; Deng, Hao; Yue, Qingwen; Ding, Jianning; Zhao, Xiangyong; Luo, Haosu

    2016-01-01

    In this work, the temperature-dependent Raman spectra and electrical properties of the [001]-oriented 0.5 mol. % Mn-doped 0.35Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3Nb2/3)O3-0.30PbTiO3-Mn (PIMNT-Mn) single crystals were investigated. All the unpoled and poled PIMNT-Mn single crystals experience a ferroelectric tetragonal phase to paraelectric cubic phase transition (FET-PC) around 183 °C (TC), which exhibits a second-order transition behavior. Whereas, the poled PIMNT-Mn single crystals exhibit another two dielectric anomalies around 130 °C (TRM) and 148 °C (TMT), in which the ferroelectric rhombohedral phase to ferroelectric monoclinic phase (FER-FEM) and the ferroelectric monoclinic phase to ferroelectric tetragonal phase (FEM-FET) transitions take place, respectively. Both the two ferroelectric phase transitions exhibit a first-order transition behavior. The discontinuous change of the phase degree (θ) and frequencies (fr and fa) around TRM suggest the occurrence of the FER-FEM phase transition in the poled PIMNT-Mn single crystals. The narrowing of the 510 cm-1 and 582 cm-1 Raman modes around the TRM, TMT, and TC temperatures shown in the temperature-dependent Raman spectra suggests their increased ordering of the local structure. The intensity ratio of I272 cm-1/I801 cm-1 increases obviously around the phase transition temperatures (TRM, TMT, and TC), indicating the reduction of the long-range order. The anomalous broadening of the 272 cm-1 Raman mode around the TRM, TMT, and TC temperatures indicates the occurrence of the successive ferroelectric phase transitions (FER-FEM, FEM-FET, and FET-PC) with increasing temperature in the poled PIMNT-Mn single crystals.

  11. Large scale prediction of soil properties in the West African yam belt based on mid-infrared soil spectroscopy

    NASA Astrophysics Data System (ADS)

    Baumann, Philipp; Lee, Juhwan; Paule Schönholzer, Laurie; Six, Johan; Frossard, Emmanuel

    2016-04-01

    Yam (Dioscorea sp.) is an important staple food in West Africa. Fertilizer applications have variable effects on yam tuber yields, and a management option solely based on application of mineral NPK fertilizers may bear the risk of increased organic matter mineralization. Therefore, innovative and sustainable nutrient management strategies need to be developed and evaluated for yam cultivation. The goal of this study was to establish a mid-infrared soil spectroscopic library and models to predict soil properties relevant to yam growth. Soils from yam fields at four different locations in Côte d'Ivoire and Burkina Faso that were representative of the West African yam belt were sampled. The project locations ranged from the humid forest zone (5.88 degrees N) to the northern Guinean savannah (11.07 degrees N). At each location, soils of 20 yam fields were sampled (0-30 cm). For the location in the humid forest zone additional 14 topsoil samples from positions that had been analyzed in the Land Degradation Surveillance Framework developed by ICRAF were included. In total, 94 soil samples were analyzed using established reference analysis protocols. Besides soils were milled and then scanned by fourier transform mid-infrared spectroscopy in the range between 400 and 4000 reciprocal cm. Using partial least squares (PLS) regression, PLS1 calibration models that included soils from the four locations were built using two thirds of the samples selected by Kennard-Stones sampling algorithm in the spectral principal component space. Models were independently validated with the remaining data set. Spectral models for total carbon, total nitrogen, total iron, total aluminum, total potassium, exchangeable calcium, and effective cation exchange capacity performed very well, which was indicated by R-squared values between 0.8 and 1.0 on both calibration and validation. For these soil properties, spectral models can be used for cost-effective, rapid, and accurate predictions

  12. Altitudinal variation of soil organic carbon stocks in temperate forests of Kashmir Himalayas, India.

    PubMed

    Ahmad Dar, Javid; Somaiah, Sundarapandian

    2015-02-01

    Soil organic carbon stocks were measured at three depths (0-10, 10-20, and 20-30 cm) in seven altitudes dominated by different forest types viz. Populus deltoides, 1550-1800 m; Juglans regia, 1800-2000 m; Cedrus deodara, 2050-2300 m; Pinus wallichiana, 2000-2300 m; mixed type, 2200-2400 m; Abies pindrow, 2300-2800 m; and Betula utilis, 2800-3200 m in temperate mountains of Kashmir Himalayas. The mean range of soil organic carbon (SOC) stocks varied from 39.07 to 91.39 Mg C ha(-1) in J. regia and B. utilis forests at 0-30 cm depth, respectively. Among the forest types, the lowest mean range of SOC at three depths (0-10, 10-20, and 20-30 cm) was observed in J. regia (18.55, 11.31, and 8.91 Mg C ha(-1), respectively) forest type, and the highest was observed in B. utilis (54.10, 21.68, and 15.60 Mg C ha(-1), respectively) forest type. SOC stocks showed significantly (R (2) = 0.67, P = 0.001) an increasing trend with increase in altitude. On average, the percentages of SOC at 0-10-, 10-20-, and 20-30-cm depths were 53.2, 26.5, and 20.3 %, respectively. Bulk density increased significantly with increase in soil depth and decreased with increase in altitude. Our results suggest that SOC stocks in temperate forests of Kashmir Himalaya vary greatly with forest type and altitude. The present study reveals that SOC stocks increased with increase in altitude at high mountainous regions. Climate change in these high mountainous regions will alter the carbon sequestration potential, which would affect the global carbon cycle. PMID:25619695

  13. Variation in soil water uptake and its effect on plant water status in Juglans regia L. during dry and wet seasons.

    PubMed

    Sun, Shou-Jia; Meng, Ping; Zhang, Jin-Song; Wan, Xianchong

    2011-12-01

    Temporal and spatial variations in the water status of walnut trees (Juglans regia L.) and the soil in which they were growing were traced by analyzing the differences in hydrogen isotopes during spring and summer in a 7-year-old walnut stand. Walnut root dynamics were measured in both dry and wet seasons. Walnut roots were mainly distributed in the upper soil (0-30 cm depth), with around 60% of the total root mass in upper soil layers and 40% in deep soil layers (30-80 cm depth). The upper soil layers contributed 68% of the total tree water requirement in the wet season, but only 47% in the dry season. In the wet season, total roots, living roots and new roots were all significantly more abundant than in the dry season. There were significant differences in pre-dawn branch percentage loss of hydraulic conductance (PLC), pre-dawn leaf water potential and transpiration between the dry and wet seasons. Water content in the upper soil layers remarkably influenced xylem water stable-hydrogen isotope (δD) values. Furthermore, there were linear relationships between the xylem water δD value and pre-dawn branch PLC, pre-dawn leaf water potential, transpiration rate and photosynthetic rate. In summary, J. regia was compelled to take a larger amount of water from the deep soil layers in the dry season, but this shift could not prevent water stress in the plant. The xylem water δD values could be used as an indicator to investigate the water stress of plants, besides probing profiles of soil water use. PMID:22116051

  14. Effects of soil data and simulation unit resolution on quantifying changes of soil organic carbon at regional scale with a biogeochemical process model.

    PubMed

    Zhang, Liming; Yu, Dongsheng; Shi, Xuezheng; Xu, Shengxiang; Xing, Shihe; Zhao, Yongcong

    2014-01-01

    Soil organic carbon (SOC) models were often applied to regions with high heterogeneity, but limited spatially differentiated soil information and simulation unit resolution. This study, carried out in the Tai-Lake region of China, defined the uncertainty derived from application of the DeNitrification-DeComposition (DNDC) biogeochemical model in an area with heterogeneous soil properties and different simulation units. Three different resolution soil attribute databases, a polygonal capture of mapping units at 1:50,000 (P5), a county-based database of 1:50,000 (C5) and county-based database of 1:14,000,000 (C14), were used as inputs for regional DNDC simulation. The P5 and C5 databases were combined with the 1:50,000 digital soil map, which is the most detailed soil database for the Tai-Lake region. The C14 database was combined with 1:14,000,000 digital soil map, which is a coarse database and is often used for modeling at a national or regional scale in China. The soil polygons of P5 database and county boundaries of C5 and C14 databases were used as basic simulation units. Results project that from 1982 to 2000, total SOC change in the top layer (0-30 cm) of the 2.3 M ha of paddy soil in the Tai-Lake region was +1.48 Tg C, -3.99 Tg C and -15.38 Tg C based on P5, C5 and C14 databases, respectively. With the total SOC change as modeled with P5 inputs as the baseline, which is the advantages of using detailed, polygon-based soil dataset, the relative deviation of C5 and C14 were 368% and 1126%, respectively. The comparison illustrates that DNDC simulation is strongly influenced by choice of fundamental geographic resolution as well as input soil attribute detail. The results also indicate that improving the framework of DNDC is essential in creating accurate models of the soil carbon cycle. PMID:24523922

  15. A new atlas of infrared methane spectra between 1120 per cm and 1800 per cm

    NASA Technical Reports Server (NTRS)

    Blatherwick, R. D.; Goldman, A.; Lutz, B. L.; Silvaggio, P. M.; Boese, R. W.

    1979-01-01

    An atlas of 1339 methane absorption lines in the range 1120 to 1800 reciprocal centimeters, including the nu(4) and nu(2) bands, is presented. Laboratory spectra were obtained by a Nicolet Fourier transform Michelson interferometer with a resolution of approximately 0.06 reciprocal cm and a path length of 6.35 m of 0.98, 4.86 and 19.97 torr. Observed spectra are also compared with spectral intensities calculated line-by-line on the basis of tabulated intensities of the observed spectral lines.

  16. Short communication: a new dataset for estimating organic carbon storage to 3 m depth in soils of the northern circumpolar permafrost region

    NASA Astrophysics Data System (ADS)

    Hugelius, G.; Tarnocai, C.; Bockheim, J. G.; Camill, P.; Elberling, B.; Grosse, G.; Harden, J. W.; Johnson, K.; Jorgenson, T.; Koven, C. D.; Kuhry, P.; Michaelson, G.; Mishra, U.; Palmtag, J.; Ping, C.-L.; O'Donnell, J.; Schirrmeister, L.; Schuur, E. A. G.; Sheng, Y.; Smith, L. C.; Strauss, J.; Yu, Z.

    2013-04-01

    High latitude terrestrial ecosystems are key components in the global carbon (C) cycle. The Northern Circumpolar Soil Carbon Database (NCSCD) was developed to quantify stocks of soil organic carbon (SOC) in the northern circumpolar permafrost region (18.7 × 106 km2). The NCSCD is a digital Geographical Information systems (GIS) database compiled from harmonized regional soil classification maps, in which data on soil coverage has been linked to pedon data from the northern permafrost regions. Previously, the NCSCD has been used to calculate SOC content (SOCC) and mass (SOCM) to the reference depths 0-30 cm and 0-100 cm (based on 1778 pedons). It has been shown that soils of the northern circumpolar permafrost region also contain significant quantities of SOC in the 100-300 cm depth range, but there has been no circumpolar compilation of pedon data to quantify this SOC pool and there are no spatially distributed estimates of SOC storage below 100 cm depth in this region. Here we describe the synthesis of an updated pedon dataset for SOCC in deep soils of the northern circumpolar permafrost regions, with separate datasets for the 100-200 cm (524 pedons) and 200-300 cm (356 pedons) depth ranges. These pedons have been grouped into the American and Eurasian sectors and the mean SOCC for different soil taxa (subdivided into Histels, Turbels, Orthels, Histosols, and permafrost-free mineral soil taxa) has been added to the updated NCSCDv2. The updated version of the database is freely available online in several different file formats and spatial resolutions that enable spatially explicit usage in e.g. GIS and/or terrestrial ecosystem models. The potential applications and limitations of the NCSCDv2 in spatial analyses are briefly discussed. An open access data-portal for all the described GIS-datasets is available online at: http://dev1.geo.su.se/bbcc/dev/v3/ncscd/download.php. The NCSCDv2

  17. Effects of sandy desertified land rehabilitation on soil carbon sequestration and aggregation in an arid region in China.

    PubMed

    Su, Yong Zhong; Wang, Xue Fen; Yang, Rong; Lee, Jaehoon

    2010-11-01

    The rehabilitation of sandy desertified land in semi-arid and arid regions has a great potential to increase carbon sequestration and improve soil quality. Our objective was to investigate the changes in the soil carbon pool and soil properties of surface soil (0-15 cm) under different types of rehabilitation management. Our study was done in the short-term (7 years) and long-term (32 years) desertification control sites in a marginal oasis of northwest China. The different management treatments were: (1) untreated shifting sand land as control; (2) sand-fixing shrubs with straw checkerboards; (3) poplar (Populus gansuensis) shelter forest; and (4) irrigated cropland after leveling sand dune. The results showed that the rehabilitation of severe sandy desertified land resulted in significant increases in soil organic C (SOC), inorganic C, and total N concentrations, as well as enhanced soil aggregation. Over a 7-year period of revegetation and cultivation, SOC concentration in the recovered shrub land, forest land and irrigated cropland increased by 4.1, 14.6 and 11.9 times compared to the control site (shifting sand land), and increased by 11.2, 17.0 and 23.0 times over the 32-year recovery period. Total N, labile C (KMnO(4)-oxidation C), C management index (CMI) and inorganic C (CaCO(3)-C) showed a similar increasing trend as SOC. The increased soil C and N was positively related to the accumulation of fine particle fractions. The accumulation of silt and clay, soil C and CaCO(3) enhanced the formation of aggregates, which was beneficial to mitigate wind erosion. The percentage of >0.25 mm dry aggregates increased from 18.0% in the control site to 20.0-87.2% in the recovery sites, and the mean weight diameter (MWD) of water-stable aggregates significantly increased, with a range of 0.09-0.30 mm at the recovery sites. Long-term irrigation and fertilization led to a greater soil C and N accumulation in cropland than in shrub and forest lands. The amount of soil C

  18. Deep soil layer is fundamental for evaluating carbon accumulation in agroecosystems

    NASA Astrophysics Data System (ADS)

    Dal Ferro, Nicola; Morari, Francesco; Simonetti, Gianluca; Polese, Riccardo; Berti, Antonio

    2015-04-01

    Soil organic carbon (SOC) is essential to secure key ecosystem services such as the provision of food and other biomass production, the filtering, buffering and transformation capacity and the climate regulation. It has been estimated that approximately 57% of the globally emitted C (8.7 Gt y-1) to the atmosphere is adsorbed by biospheric C pools, ascertaining the potential soil C sink capacity of managed ecosystems at 55 to 78 Gt, of which only 50 to 66% attainable. Therefore it is essential the full knowledge of soil management practices that can affect SOC dynamics and, in turn, climate change. Several studies focussed on the evaluation of the best cropping management practices to accumulate C in the soil profile. Nevertheless, in most cases soil analyses were made in the topsoil (generally in the 0-30 cm layer), ignoring the effect of C translocation in the deeper soil profile as a result of tillage practices, crop root deepening etc. In this context, in a long-term experiment established in the early 1960s, we quantified the SOC accumulation within the soil profile (0-90 cm) and evaluate the effects of different cropping system on SOC dynamics. The experiment is located at the experimental farm of the University of Padova, in northeastern Italy. The trial compares four rotations with three levels of mineral fertilisation and with or without organic fertilisation. The rotations considered are: continuous crops (grain maize, forage maize, winter wheat and permanent meadow); two-year (maize-wheat); four-year (sugarbeet, soybean, wheat, maize) and six-year (maize, sugarbeet, maize, wheat, alfalfa, alfalfa) with different levels of mineral, organic and mixed fertilisations. Crops with superficially developed rooting systems (e.g. permanent meadow) highly increased SOC only in the topsoil. This effect was enhanced by the contribution of organic amendment-C. Root-derived carbon played a pivotal role also in the deepest soil profile (60-90 cm) by increasing the SOC

  19. Effect of winglets on a first-generation jet transport wing. 3: Pressure and spanwise load distributions for a semispan model at Mach 0.30. [in the Langley 8 ft transonic tunnel

    NASA Technical Reports Server (NTRS)

    Montoya, L. C.; Jacobs, P. F.; Flechner, S. G.

    1977-01-01

    Pressure and spanwise load distributions on a first-generation jet transport semispan model at a Mach number of 0.30 are given for the basic wing and for configurations with an upper winglet only, upper and lower winglets, and a simple wing-tip extension. To simulate second-segment-climb lift conditions, leading- and/or trailing-edge flaps were added to some configurations.

  20. Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape

    NASA Astrophysics Data System (ADS)

    Boutton, T. W.; Liao, J. D.

    2010-09-01

    Subtropical woodlands dominated by N-fixing tree legumes have largely replaced grasslands in the Rio Grande Plains, southwestern United States, during the past century. To evaluate the impact of this vegetation change on the N cycle, we measured the mass and isotopic composition (δ15N) of N in the soil system of remnant grasslands and woody plant stands ranging in age from 10 to 130 years. Nitrogen accumulated at linear rates following woody encroachment in the litter (0.10-0.14 g N m-2 yr-1), roots (0.63-0.98 g N m-2 yr-1), and soils (0.75-3.50 g N m-2 yr-1), resulting in a 50%-150% increase in N storage in the soil system (0-30 cm) in woody stands older than 60 years. Simultaneous decreases in soil δ15N of up to 2‰ in the upper 30 cm of the profile are consistent with a scenario in which N inputs have exceeded losses following woody encroachment and suggest N accrual was derived from symbiotic N fixation by tree legumes and/or differential atmospheric N deposition to wooded areas. Vertical uplift and lateral transfer of N by the more deeply and intensively rooted woody plants may have contributed to N accumulation in wooded areas, but soil δ15N values are inconsistent with this explanation. N accumulation following woody encroachment may alter soil N availability, species interactions and successional dynamics, flux rates of key trace gases such as NOX and N2O and ecosystem C sequestration. Given the geographic dimensions of woody encroachment, these results may have implications for atmospheric composition and the climate system.

  1. Reverse bias voltage testing of 8 cm x 8cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Woike, T.; Stotlar, S.; Lungu, C.

    1991-01-01

    A study is described of the reverse I-V characteristics of the largest space qualified silicon solar cells currently available (8 x 8 cm) and of reverse bias voltage (RBV) testing performed on these cells. This study includes production grade cells, both with and without cover glass. These cells span the typical output range seen in production. Initial characteristics of these cells are measured at both 28 and 60 C. These measurements show weak correlation between cell output and reverse characteristics. Analysis is presented to determine the proper conditions for RBV stress to simulate shadowing effects on a particular array design. After performing the RBV stress the characteristics of the stressed cells are remeasured. The degradation in cell performance is highly variable which exacerbates cell mismatching over time. The effect of this degradation on array lifetime is also discussed. Generalization of these results to other array configurations is also presented.

  2. The clumped isotope geothermometer in soil and paleosol carbonate

    NASA Astrophysics Data System (ADS)

    Quade, J.; Eiler, J.; Daëron, M.; Achyuthan, H.

    2013-03-01

    We studied both modern soils and buried paleosols in order to understand the relationship of temperature (T°C(47)) estimated from clumped isotope compositions (Δ47) of soil carbonates to actual surface and burial temperatures. Carbonates from modern soils with differing rainfall seasonality were sampled from Arizona, Nevada, Tibet, Pakistan, and India. T°C(47) obtained from these soils shows that soil carbonate forms in the warmest months of the year, in the late morning to afternoon, and probably in response to intense soil dewatering. T°C(47) obtained from modern soil carbonate ranges from 10.8 to 39.5 °C. On average, T°C(47) exceeds mean annual temperature by 10-15 °C due to summertime bias in soil carbonate formation, and to summertime ground heating by incident solar radiation. Secondary controls on T°C(47) are soil depth and shading. Site mean annual air temperature (MAAT) across a broad range (0-30 °C) of site temperatures is highly correlated with T°C(47) from soils, following the equation: MAAT(°C)=1.20(T°C(47)0)-21.72(r2=0.92) where T°C(47)0 is the effective air temperature at the site estimated from T°C(47). The effective air temperature represents the air temperature required to account for the T°C(47) at each site, after consideration of variations in T°C(47) with soil depth and ground heating. The highly correlated relationship in this equation should now permit mean annual temperature in the past to be reconstructed from T°C(47) in paleosol carbonate, assuming one is studying paleosols that formed in environments generally similar in seasonality and ground cover to our calibration sites. T°C(47)0 decreases systematically with elevation gain in the Himalaya, following the equation: elevation(m)=-229(T°C(47)0)+9300(r2=0.95) Assuming that temperature varied similarly with elevation in the past, this equation can be used to reconstruct paleoelevation from clumped isotope analysis of ancient soil carbonates. We also measured T°C(47

  3. Agricultural practices that store organic carbon in soils: is it only a matter of inputs ?

    NASA Astrophysics Data System (ADS)

    Chenu, Claire; Cardinael, Rémi; Autret, Bénédicte; Chevallier, Tiphaine; Girardin, Cyril; Mary, Bruno

    2016-04-01

    Increasing the world soils carbon stocks by a factor of 4 per mil annually would compensate the annual net increase of CO2 concentration in the atmosphere. This statement is the core of an initiative launched by the French government at the recent COP21, followed by many countries and international bodies, which attracts political attention to the storage potential of C in soils. Compared to forest and pasture soils, agricultural soils have a higher C storage potential, because they are often characterized by low C contents, and increasing their C content is associated with benefits in terms of soil properties and ecosystem services. Here we quantified, under temperate conditions, the additional C storage related to the implementation of two set of practices that are recognized to be in the framework of agroecology: conservation tillage on the one hand and agroforestry on the other hand. These studies were based on long-term experiments, a 16-years comparison on cropping systems on luvisols in the Paris area and a 18-year-old silvoarable agroforestry trial, on fluvisols in southern France, the main crops being cereals in both cases. C stocks were measured on an equivalent soil mass basis. Both systems allowed for a net storage of C in soils, which are, for the equivalent of the 0-30 cm tilled layer, of 0.55 ± 0.16 t ha‑ 1 yr‑ 1 for conservation agriculture (i.e. no tillage with permanent soil coverage with an associated plant, fescue or alfalfa) and of 0.25 ± 0.03 t ha-1 yr-1 for the agroforestry system. These results are in line with estimates proposed in a recent French national assessment concerning the potential of agricultural practices to reduce greenhouse gas emissions. Compared to recent literature, they further show that practices that increase C inputs to soil through additional biomass production would be more effective to store C in soil (tree rows, cover crops in conservation agriculture) than practices, such as no-tillage, that are assumed to

  4. Assessment of total soil and plant trace elements in rice-based production systems in NE Italy

    NASA Astrophysics Data System (ADS)

    Bini, Claudio; Nadimi-Goki, Mandana; Kato, Yoichi; Vianello, Gilmo; Vittori, Livia; Wahsha, Mohammad; Spiandorello, Massimo

    2014-05-01

    Macro- and micronutrients concentrations, and PTEs contents in soils and plants (rice) from the rice district in the Venetian territory (NE Italy) have been determined by ICP-MS spectrometry, with the following aims: - to determine the background levels of macro- and microelements in the study area; - to assess possible contamination of soils and plants; - to calculate the Translocation Factor (TF) of metals from soil to plant, and the possible hazard for human health. Four rice plots with different rotation systems were investigated from seedling time to harvesting; sampling of soils (0-30cm) and plants was carried out 4 times during growing season (three replicates). Rice plants were separated into roots, stems, leaves and grains, and then oven-dried. Chemical and physical analyses were carried out at the Soil Science Lab of the University of Bologna and Venice, respectively. The results obtained point to a land with moderate soil contamination by trace elements (namely Li, Sn, Tl, Sr, Ti, Fe). Heavy metal (Sb, As, Be, Cd, Co, Cr, Ni, Pb, Cu, V, Zn ) concentrations in soils are below the threshold indicated by the Italian legislation (DM 152/2006). Cd, Sn, and Ti contents in soils are positively correlated with soil pH, while As, Fe, Li, Ti, Tl and Zn are negatively correlated with organic matter content. With the exception of Strontium, soil metal contents are always correlated between variable couples. HMs in plants vary according to the sampling season, texture and moisture, and soil pH. Most non-essential trace elements are accumulated in rice roots and, only in cases of essential micronutrients, in leaves. Therefore, rice can be assumed as an accumulator plant of As, Pb, Cr, Ba, and Ti, whereas it is as an indicator plant for Cu, Fe, Ni, Mn and Zn. The results of multiple linear regression analysis showed that soil pH has a larger effect on Ba, Cr, Cu, Fe, Mn, Ni, Ti and Zn concentrations in grain than other soil parameters. The average translocation of

  5. Managing compost stability and amendment to soil to enhance soil heating during soil solarization.

    PubMed

    Simmons, Christopher W; Guo, Hongyun; Claypool, Joshua T; Marshall, Megan N; Perano, Kristen M; Stapleton, James J; Vandergheynst, Jean S

    2013-05-01

    Soil solarization is a method of soil heating used to eradicate plant pathogens and weeds that involves passive solar heating of moist soil mulched (covered) with clear plastic tarp. Various types of organic matter may be incorporated into soil prior to solarization to increase biocidal activity of the treatment process. Microbial activity associated with the decomposition of soil organic matter may increase temperatures during solarization, potentially enhancing solarization efficacy. However, the level of organic matter decomposition (stability) necessary for increasing soil temperature is not well characterized, nor is it known if various amendments render the soil phytotoxic to crops following solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays. Amendment of soil with 10%(g/g) compost containing 16.9 mg CO2/gdry weight organic carbon resulted in soil temperatures that were 2-4 °C higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. PMID:23422041

  6. Soil organic carbon sequestration potential and gap of the sub-tropical region

    NASA Astrophysics Data System (ADS)

    Chiti, T.; Santini, M.; Valentini, R.

    2012-04-01

    A database of soil organic carbon (SOC) stocks was created for the sub-tropical belt using existing global SOC databases (WISE3; various SOTER) and new data from an ongoing project (ERC Africa-GHG) specific for the tropical forests of the African continent. The intent of this database is to evaluate the sequestration potential of a critical area of the world where most of the primary rainforests are located, and actually show undoubtedly high SOC losses associated with deforestation. About 4100 profiles, quite well distributed over the entire sub-tropical belt, were used to calculate the actual SOC stock for the 0-30 cm and 30-100 cm depths of mineral soil. First, this actual SOC stock has been related to the current Land Use Systems; successively, it has been interpolated taking into account Homogeneous Land Units (HLUs) in terms of soil type, climate zone and land use. Then, relying on consistent projections, of both climate and land use changes, for the years 2050 and 2100 under extremes IPCC-SRES emission scenarios such as the B1 and the A2, potential SOC stocks for these time frames has been calculated. Soil carbon sequestration gap is calculated by the difference of the actual SOC stock and the future projections. When subtracting potential from the actual SOC stocks, negative values represent a gap in terms of possible SOC losses and so reduced carbon sequestration. The soil carbon gap indicates locations where there will be low soil-carbon levels associated with medium-to-high actual SOC stocks, and medium soil-carbon levels associated with high actual SOC stocks, depending on soil type, climate and land use conditions. On the long term, 2076-2100, a SOC gap is observed under all scenarios in South America, just below the Amazonia basin, where are located open and fragmented forests. However, in the Amazonia basin deforestation decrease since no sensible SOC losses were observed. An important gap is observed also in the Congo basin and West Africa, but the

  7. Contrasting effects of biochar versus manure on soil microbial communities and enzyme activities in an Aridisol.

    PubMed

    Elzobair, Khalid A; Stromberger, Mary E; Ippolito, James A; Lentz, Rodrick D

    2016-01-01

    Biochar can increase microbial activity, alter microbial community structure, and increase soil fertility in arid and semi-arid soils, but at relatively high rates that may be impractical for large-scale field studies. This contrasts with organic amendments such as manure, which can be abundant and inexpensive if locally available, and thus can be applied to fields at greater rates than biochar. In a field study comparing biochar and manure, a fast pyrolysis hardwood biochar (22.4 Mg ha(-1)), dairy manure (42 Mg ha(-1) dry wt), a combination of biochar and manure at the aforementioned rates, or no amendment (control) was applied to an Aridisol (n=3) in fall 2008. Plots were annually cropped to corn (Zea maize L.). Surface soils (0-30 cm) were sampled directly under corn plants in late June 2009 and early August 2012, and assayed for microbial community fatty acid methyl ester (FAME) profiles and six extracellular enzyme activities involved in soil C, N, and P cycling. Arbuscular mycorrhizal (AM) fungal colonization was assayed in corn roots in 2012. Biochar had no effect on microbial biomass, community structure, extracellular enzyme activities, or AM fungi root colonization of corn. In the short-term, manure amendment increased microbial biomass, altered microbial community structure, and significantly reduced the relative concentration of the AM fungal biomass in soil. Manure also reduced the percent root colonization of corn by AM fungi in the longer-term. Thus, biochar and manure had contrasting short-term effects on soil microbial communities, perhaps because of the relatively low application rate of biochar. PMID:26138708

  8. Repeated annual paper mill and alkaline residuals application affects soil metal fractions.

    PubMed

    Gagnon, Bernard; Robichaud, Annie; Ziadi, Noura; Karam, Antoine

    2014-03-01

    The application of industrial residuals in agriculture may raise concerns about soil and crop metal accumulation. A complete study using a fractionation scheme would reveal build-up in metal pools occurring after material addition and predict the transformation of metals in soil between the different forms and potential metal release into the environment. An experimental study was conducted from 2000 to 2008 on a loamy soil at Yamachiche, Quebec, Canada, to evaluate the effects of repeated annual addition of combined paper mill biosolids when applied alone or with several liming by-products on soil Cu, Zn, and Cd fractions. Wet paper mill biosolids at 0, 30, 60, or 90 Mg ha and calcitic lime, lime mud, or wood ash, each at 3 Mg ha with 30 Mg paper mill biosolids ha, were surface applied after seeding. The soils were sampled after 6 (soybean [ (L.) Merr.]) and 9 [corn ( L.)] crop years and analyzed using the Tessier fractionation procedure. Results indicated that biosolids addition increased exchangeable Zn and Cd, carbonate-bound Cd, Fe-Mn oxide-bound Zn and Cd, organically bound Cu and Zn, and total Zn and Cd fractions but decreased Fe-Mn oxide-bound Cu in the uppermost 30-cm layer. With liming by-products, there was a shift from exchangeable to carbonate-bound forms. Even with very small metals addition, paper mill and liming materials increased the mobility of soil Zn and Cd after 9 yr of application, and this metal redistribution resulted into higher crop grain concentrations. PMID:25602653

  9. SOIL BIN AND FIELD TESTS OF AN ON-THE-GO SOIL STRENGTH PROFILE SENSOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    n on-the-go soil strength profile sensor (SSPS) was previously developed to measure the within-field spatial variability in soil strength at 5 evenly-spaced depths up to 50 cm. In this paper, performance of the SSPS was evaluated using soil bin and field data. First, the SSPS was tested in a soil bi...

  10. Soil fungal community shift evaluation as a potential cadaver decomposition indicator.

    PubMed

    Chimutsa, Monica; Olakanye, Ayodeji O; Thompson, Tim J U; Ralebitso-Senior, T Komang

    2015-12-01

    Fungi metabolise organic matter in situ and so alter both the bio-/physico-chemical properties and microbial community structure of the ecosystem. In particular, they are responsible reportedly for specific stages of decomposition. Therefore, this study aimed to extend previous bacteria-based forensic ecogenomics research by investigating soil fungal community and cadaver decomposition interactions in microcosms with garden soil (20 kg, fresh weight) and domestic pig (Sus scrofa domesticus) carcass (5 kg, leg). Soil samples were collected at depths of 0-10 cm, 10-20 cm and 20-30 cm on days 3, 28 and 77 in the absence (control -Pg) and presence (experimental +Pg) of Sus scrofa domesticus and used for total DNA extraction and nested polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) profiling of the 18S rRNA gene. The Shannon-Wiener (H') community diversity indices were 1.25±0.21 and 1.49±0.30 for the control and experimental microcosms, respectively, while comparable Simpson species dominance (S) values were 0.65±0.109 and 0.75±0.015. Generally, and in contrast to parallel studies of the bacterial 16S rRNA and 16S rDNA profiles, statistical analysis (t-test) of the 18S dynamics showed no mathematically significant shifts in fungal community diversity (H'; p=0.142) and dominance (S; p=0.392) during carcass decomposition, necessitating further investigations. PMID:26322496

  11. Land-use induced dynamics of C, N and P in mountain soils of South Ecuador

    NASA Astrophysics Data System (ADS)

    Hamer, U.; Potthast, K.; Makeschin, F.

    2009-04-01

    The mountain rainforest region in South Ecuador is characterised by sites subjected to forest clearing by slash burn for pasture production. Repeated burning of pastures is a common management practice in South Ecuador. With ongoing pasture age bracken (Pteridium arachnoideum) outcompetes the pasture grass (Setaria sphacelata), pastures are abandoned and a vegetation succession develops. Along a land-use gradient (natural forest, young and old pasture, abandoned pasture with successional vegetation) the dynamics of C, N and P in the mountain soils were investigated. The study sites were located close to the "Estacion Científica San Francisco", about halfway between the province capitals Loja and Zamora, in the Cordillera Real, an eastern range of the South Ecuadorian Andes at about 2000 m above sea level. The mean annual air temperature is 15.3°C with an average annual rainfall of 2176 mm. The land-use change induced an increase of total P in the top soil (0-30 cm) of young and old pastures. An increase in SOC stocks in the top soil of the old pasture was combined with an increase in the proportion of NaOH extractable organic P. In the young pasture soil the mineralization of SOC and the amounts of microbial biomass C, N and P were highest. In 0-5 cm depth gross N mineralization and gross NH4 consumption rates were significantly higher in the young pasture compared to forest and abandoned pasture. Thus, the initial increase in microbial activity after forest to pasture conversion seems to slow down with increasing pasture age. Burning on the abandoned pasture site induced a short-term and short-lived increase in gross N mineralization rates. First results indicate that the land-use induced changes in mineralization rates were connected with changes in the microbial community structure.

  12. Mapping of reciprocal space of La{sub 0.30}CoO{sub 2} in 3D: Analysis of superstructure diffractions and intergrowths with Co{sub 3}O{sub 4}

    SciTech Connect

    Brázda, Petr; Knížek, Karel

    2015-07-15

    We have used electron diffraction tomography and powder X-ray diffraction to elucidate the structural properties of layered cobaltate γ-La{sub 0.30}CoO{sub 2}. The structure consists of hexagonal sheets of edge-sharing CoO{sub 6} octahedra interleaved by lanthanum monolayers. The La{sup 3+} cations occupy only one third of available P2 sites, forming a 2-dimensional a√3×a√3 superstructure in a–b plane. The results show that there exists no order in the mutual relative shift between the neighbouring La interlayers within the a–b plane. This is manifested in the observed monotonous decrease of the diffracted intensity of the superstructure diffractions along c{sup ⁎} in both X-ray and electron diffraction data. The observed lack of stacking order differentiates the La{sub x}CoO{sub 2} from its Ca and Sr analogues where at least a partial stacking order of the cationic interlayers is manifested in experimental data published in literature. - Highlights: • We use electron diffraction tomography for reciprocal space mapping of La{sub 0.30}CoO{sub 2}. • We observed a complete disorder of the stacking of Lanthanum interlayers. • Co{sub 3}O{sub 4} intergrown with La{sub 0.30}CoO{sub 2} crystals brings about fake superstructure diffractions. • Twinning of Co{sub 3}O{sub 4} enhances the problem of fake superstructure diffractions.

  13. Dynamics of carbon in deep soils inferred from carbon stable isotopes signatures : a worldwide meta-analysis

    NASA Astrophysics Data System (ADS)

    Balesdent, Jérôme; Basile-Doelsch, Isabelle; Chadoeuf, Joël; Cornu, Sophie; Derrien, Delphine; Fekiacova, Zuzana; Hatté, Christine

    2014-05-01

    The contribution of soil carbon deeper than 30 cm to the atmospheric carbon balance is still poorly understood. A very straightforward quantification of the gross exchange of carbon between the atmosphere and soil organic matter can be obtained at places where the 13C/12C signature of vegetation has been changed for known durations, due to switch of the photosynthetic metabolism (C3 or C4) or to Free Air Carbon Enrichment experiments. We compiled C and 13C profile data of 113 sites of this type, either gahered from the literature or from our own measurements. Each site comprised two profiles : one where the 13C/12C of the vegetation had been changed, and a reference profile with unchanged vegetation 13C/12C. An isotope mixing equation was used, which takes into account the natural isotope enrichments with depth and decay. Three main variables were calculated at any depth from 0 to 100 cm and in a few sites down to 200 cm : the carbon content, the proportion of new carbon (aged less than the duration of change t) and the amount of new carbon. The database concerned 23 countries, various climates (58% intertropical and 42% between 23° to 56° latitude) and various soil types and textures. Landuses and vegetation consisted in 26% of forests and woodlands, 35% of grasslands and 38% of cropped systems. The duration of the natural labelling t ranged from 2 years to ca. 4000 years. Peatlands, boreal, and desert environments were absent from the database. Non-linear regressions with time across the dataset yielded kinetic parameters of the age distribution on one hand and of the flux of new carbon incorporation (kg C m-2 yr-1) on the other, each calculated by 10 cm depth increments. On the average, the median ages of carbon increase from ca. 15 years at 0 cm to more than 1000 years at 100 cm. Turnover is on the average 2 to 3 times slower for the subsoil (30-100 cm) than for the topsoil (0-30 cm). Based on the incorporation of new C in the first decades, the carbon input

  14. Effect of DTPA on concentration ratios of /sup 237/Np and /sup 244/Cm in vegetative parts of bush bean and barley

    SciTech Connect

    Romney, E.M.; Wallace, A.; Mueller, R.T.; Cha, J.W.; Wood, R.A.

    1981-07-01

    We grew bush beans, barley, and rice in two different soils in a glasshouse with /sup 237/Np or /sup 244/Cm mixed into separate containers of the soil. The chelating agent DTPA at 100 ..mu..g/g soil was added to half of the containers. The concentration ratio (CR) for /sup 237/Np without DTPA was two orders of magnitude higher than for /sup 244/Cm without DTPA for all three plant species. The DTPA increased the CR of /sup 244/Cm by two to three orders of magnitude, but had no influence on that for /sup 237/Np. In bush beans, both /sup 237/Np and /sup 244/Cm CRs were higher in primary leaves than in trifoliate leaves, which were higher than for stems. The CRs for bush beans were generally higher for both /sup 237/Np and /sup 244/Cm than for either barley or rice, especially without DTPA.

  15. Lessons Learned From CM-2 Modal Testing and Analysis

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.; Carney, Kelly S.; Otten, Kim D.

    2002-01-01

    The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS-107 in the SPACEHAB Double Research Module. The CM-2 flight hardware is installed into SPACEHAB single and double racks. The CM-2 flight hardware was vibration tested in the launch configuration to characterize the structure's modal response. Cross-orthogonality between test and analysis mode shapes were used to assess model correlation. Lessons learned for pre-test planning and model verification are discussed.

  16. Visualization on massively parallel computers using CM/AVS

    SciTech Connect

    Krogh, M.F.; Hansen, C.D.

    1993-09-01

    CM/AVS is a visualization environment for the massively parallel CM-5 from Thinking Machines. It provides a backend to the standard commercially available AVS visualization product. At the Advanced Computing Laboratory at Los Alamos National Laboratory, we have been experimenting and utilizing this software within our visualization environment. This paper describes our experiences with CM/AVS. The conclusions reached are applicable to any implimentation of visualization software within a massively parallel computing environment.

  17. Energy Levels of the Nitrate Radical Below 2000 CM-1

    NASA Astrophysics Data System (ADS)

    Stanton, J. F.; Simmons, C. S.

    2012-06-01

    Highly sophisticated quantum chemistry techniques have been employed to build a three-state diabatic Hamiltonian for the nitrate radical (NO_3). Eigenvalues of this Hamiltonian (which includes effects beyond the Born-Oppenheimer approximation) are consistent with the known ``vibrational'' levels of NO_3 up to ca. 2100 cm-1 above the zero-point level; with a small empirical adjustment of the diabatic coupling strength, calculated levels are within 20 cm-1 of the measured level positions for those that have been observed experimentally. Of the eleven states with e' symmetry calculated below 2000 cm-1, nine of these have been observed either in the gas phase by Hirota and collaborators as well as Neumark and Johnston, or in frozen argon by Jacox. However, the Hamiltonian produces two levels that have not been seen experimentally: one calculated to lie at 1075 cm-1 (which is the third e' state, above ν_4 and 2ν_4) and another at 1640 cm-1 which is best assigned as one of the two e' sublevels of 4ν_4. A significant result is that the state predicted at 1075 cm-1 is not far enough above the predicted 2ν_4 level (777 cm-1 v. ca. 760 cm-1 from experiment) to be plausibly assigned as 3ν_4 (which is at 1155 cm-1: experimental position: 1173 cm-1), nor is its nodal structure consistent with such an idea. Rather, it is quite unambiguously the ν_3 level. Given the fidelity of the results generated by this model Hamiltonian as compared to experiment, it can safely be concluded that the prominent infrared band seen at 1492 cm-1 (corresponding to a calculated level at 1500 cm-1) is not ν_3, but rather a multiquantum state best viewed as a sublevel of the ν_3 + ν_4 combination.

  18. The amino acid composition of the Sutter's Mill CM2 carbonaceous chondrite

    NASA Astrophysics Data System (ADS)

    Burton, Aaron S.; Glavin, Daniel P.; Elsila, Jamie E.; Dworkin, Jason P.; Jenniskens, Peter; Yin, Qing-Zhu

    2014-11-01

    We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25-26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low D/L ratios of several proteinogenic amino acids. The D/L ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional L-amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β-alanine, and γ-amino-n-butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of D+L-β-aminoisobutyric acid (β-AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β-AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound-specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20-fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.

  19. Evaluation of Long-term Agroecosystem Management on Changes in Subsurface vs. Surface Soil Carbon Fractions and Dynamics

    NASA Astrophysics Data System (ADS)

    Wolfe, D.; Beem-Miller, J.; Kong, A.; Comstock, J.; Sherpa, S.; Wine, E.; Mallorino, A.

    2013-12-01

    Most studies of terrestrial soil organic carbon (SOC) have focused on the upper soil profile (e.g., 0-30 cm), so our knowledge of C dynamics in deeper layers is incomplete. Here, we examine the depth-dependent mechanisms and constraints by which management of the upper soil profile for optimum crop yield in agroecosystems can influence SOC fractions and change in both the surface and subsurface. Our study includes continuous corn systems under long-term conventional tillage (CT) vs no-tillage (NT) at Willsboro, New York (NY) (Kingsbury silty loam soil; 19 y) and Chazy, NY (Raynham silt loam; 38 y), and long-term crop rotation experiments under CT at Algona, Iowa (IA) (Clarion loam; 11 y) and Kanawha, IA (Canisteo clay loam; 57 y). Rotations in IA compared continuous corn to corn rotations with soybean, alfalfa, and/or oats. Cores were collected in 2011 and 2012 at 0-10, 10-20, 20-30, 30-50 and 50-75 cm, and analyzed for bulk density, soil texture, percent organic matter, total C and nitrogen (N), soil inorganic C, and active C (permanganate oxidizable C, POXC). Recent studies have documented that POXC is closely correlated with heavy, small-sized particulate organic C, reflecting a relatively processed and stable pool of labile C that is well-suited to assess land management effects on C dynamics. Overall, cumulative SOC stocks (0-75 cm) in the IA and NY soils ranged from 109.9-168.8 MgC ha-1, and 37.8-104.1 MgC ha-1, respectively. The proportion of total SOC stocks that occurred in the subsurface (30-75 cm) ranged from 39-44% in the IA soils, compared to 16-26% in NY. Across all sites and management we found no examples of statistically significant SOC change below 30 cm, although this may be in part an artifact of greater variability and smaller absolute values of C concentration at depth. SOC data were correlated with POXC measurements, although depth- and site-specific discrepancies in these two measures were observed. For example, POXC was relatively

  20. The role of irrigation in the soil-crop system

    NASA Astrophysics Data System (ADS)

    Széles, Adrienn; Ragán, Péter; Nagy, János

    2015-04-01

    Agricultural production is performed in 85.5% of the total area of Hungary. Yearly average precipitation is 550-600 mm. Due to global warming, flooding, inland inundation and drought are frequent within a year. Extreme weather circumstances pose new challenges for crop producers. The results of long-term field experiments provide guidance to how each production technological intervention affects crop production, average yield and yield security. Examinations were performed on mid-heavy calcareous chenozem soil in a multifactorial small plot long-term field experiment under natural precipitation supply and irrigated circumstances to analyse the effect of irrigation and N fertilisation on soil moisture and maize grain yield. Drought and optimal years were involved in the examination. Six fertiliser treatments were used (0, 30, 60, 90, 120, 150 kg N ha-1) each year. Irrigation was performed with a Valmont linear equipment. Changes in soil moisture balance were examined with TDR-based soil moisture probes in the 0-120 cm profile. Evaluation was performed with SPSS. The moisture profiles of the 1.2 m soil profile show contrasting tendencies in different crop years in both irrigation treatments. In drought years, the 0-0.15 m layer showed the lowest moisture values (8.3-9.6 v/v%), increasing towards deeper layers. The significant (p<0.05) moisture content difference of 11-12 v/v% measured at the 12-leaf-stage constantly decreased by the end of the growing season as soil moisture stock decreased. In wet years, the highest moisture content was observed in the 0.15-0.30 m layer (37-39v/v%), decreasing towards deeper layers (13-16 v/v%). At natural precipitation supply, yield linearly increased until 60 kg ha-1 N in both years, but no yield surplus was obtained above this dose. Our results show that increasing N doses do not always cause yield increase if the water needed for nutrient uptake is limited. In irrigated treatments, the highest statistically significant yield was

  1. Frustrated exchange interactions formation at low temperatures and high hydrostatic pressures in La{sub 0.70}Sr{sub 0.30}Mn{sub O2.85}

    SciTech Connect

    Trukhanov, S. V. Trukhanov, A. V.; Vasiliev, A. N.; Szymczak, H.

    2010-08-15

    The magnetic and thermal properties of the anion-deficient La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} manganite are investigated in wide temperature (4-350 K) range, including under hydrostatic pressure (0-1.1 GPa). Throughout the pressure range investigated, the sample is spin glass with diffused phase transition into paramagnetic state. It is established, that spin glass state is a consequence of exchange interaction frustration of the ferromagnetic clusters embeded into antiferromagnetic clusters. The magnetic moment freezing temperature T{sub f} of ferromagnetic clusters increases under pressure, freezing temperature dependence on pressure is characterized by derivative value {approx}4.5 K/GPa, while the magnetic ordering T{sub MO} temperature dependence is characterized by derivative value {approx}13 K/GPa. The volume fraction of sample having ferromagnetic state is V{sub fer} {approx} 13% and it increases under a pressure of 1.1 GPa by {Delta}V{sub fer} {approx} 6%. Intensification of ferromagnetic properties of the anion-deficient La{sub 0.70}Sr{sub 0.30}MnO{sub 2.85} manganite under hydrostatic pressure is a consequence of oxygen vacancies redistribution and unit cell parameters decrease. The most likely mechanism of frustrated exchange interactions formation is discussed.

  2. Distorted weak anti-localization effects in Bi2Se3/La0.70Sr0.30MnO3 (TI/FM) heterostructures grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Hunte, Frank; Kumar, Raj; Lee, Yi-Fang; Punugupati, Sandhyarani; Schwartz, Justin; Narayan, Jay

    Topological insulator/ferromagnet (TI/FM) heterostructures with broken time reversal symmetry by interface-induced magnetism are the potential platforms for the observation of novel quantum transport phenomena, magnetic monopoles and exotic quantum magneto-electric effects. TI/FM heterostructures with low Curie temperature ferromagnets i. e. GdN, EuS have been fabricated and studied. One of the challenges encountered with these heterostructures is their low Curie temperatures which limits their potential for applications in spintronic devices at room temperature. To address this issue, we have grown Bi2Se3/La0.70Sr0.30MnO3 (TI/FM) heterostructures by the method of pulsed laser deposition. La0.70Sr0.30MnO3(LSMO) is a strong ferromagnetic material with Tc ~350 K and Bi2Se3 is the most studied topological insulator. XRD and phi scan results show that epitaxial thin films of Bi2Se3 are grown on the LSMO template. Strong in-plane magnetization is confirmed by magnetometry measurements of the Bi2Se3/LSMO heterostructure. Magneto-transport measurements show a distorted weak anti-localization effect with hysteretic behavior due to interface induced ferromagnetism in the Bi2Se3 TI films. This work was supported, in part, by National Science Foundation ECCS-1306400.

  3. Electrical conductivity and complex impedance analysis of La0.7-xNdxSr0.3Mn0.7Ti0.3O3 (x≤0.30) perovskite

    NASA Astrophysics Data System (ADS)

    Abassi, Amel; Kallel, Nabil; Kallel, Sami; Khirouni, Kamel; Peña, Octavio

    2016-03-01

    Polycrystalline samples La0.7-xNdxSr0.3Mn0.7Ti0.3O3 (x=0.10; 0.20 and 0.30) were prepared by a high-temperature solid-state reaction technique. The X-ray diffraction shows that all the samples crystallize in the orthorhombic structure, Pbnm space group, with presence of a minor unreacted Nd2O3. The electrical response was studied by impedance complex spectroscopy over a broad frequency range (40-100 MHz) at room temperature. The values of ac conductivity for all samples were fitted by the Jonscher law σ (ω) = σdc + Aωs . For x=0.10 and 0.20, hopping occurs between neighboring sites, whereas for x=0.30 the hopping process occurs through longer distance. Complex impedance plots exhibit semicircular arcs described by an electrical equivalent circuit, which indicates that the Nd-doped compounds obey a non-Debye relaxation process.

  4. Soil water repellency of Antarctic soils (Elephant Point). First results

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Oliva, Marc; Ruiz Fernández, Jesus

    2015-04-01

    Hydrophobicity it is a natural properties of many soils around the world. Despite the large body of research about soil water hydrophobicity (SWR) in many environments, little information it is available about Antarctic soils and their hydro-geomorphological consequences. According to our knowledge, no previous work was carried out on this environment. Soil samples were collected in the top-soil (0-5 cm) and SWR was analysed according to the water drop penetration test. The preliminary results showed that all the soils collected were hydrophilic, however further research should be carried out in order to understand if SWR changes with soil depth and if have implications on soil infiltration during the summer season.

  5. "The 5 cm Rule": Biopower, Sexuality and Schooling

    ERIC Educational Resources Information Center

    Allen, Louisa

    2009-01-01

    This paper explores "the 5 cm rule", a regulation around student contact discovered during an investigation of the sexual culture of schooling with 16-19-year-olds in New Zealand. Implemented to stem "inappropriate and unwanted" touching, it stipulates that students must maintain a physical distance of 5 cm at all times. It is argued this rule…

  6. Design and Performance of 40 cm Ion Optics

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2001-01-01

    A 40 cm ion thruster is being developed at the NASA Glenn Research Center to obtain input power and propellant throughput capabilities of 10 kW and 550 kg. respectively. The technical approach here is a continuation of the "derating" technique used for the NSTAR ion thruster. The 40 cm ion thruster presently utilizes the NSTAR ion optics aperture geometry to take advantage of the large database of lifetime and performance data already available. Dome-shaped grids were chosen for the design of the 40 cm ion optics because this design is naturally suited for large-area ion optics. Ion extraction capabilities and electron backstreaming limits for the 40 cm ion optics were estimated by utilizing NSTAR 30 cm ion optics data. A preliminary service life assessment showed that the propellant throughput goal of 550 kg of xenon may be possible with molybdenum 40 cm ion optics. One 40 cm ion optics' set has been successfully fabricated to date. Additional ion optics' sets are presently being fabricated. Preliminary performance tests were conducted on a laboratory model 40 cm ion thruster.

  7. Photofraction of a 5 cm x 2 cm BGO scintillator. [bismuth germanate crystal for use in cosmic gamma ray detector

    NASA Technical Reports Server (NTRS)

    Dunphy, P. P.; Forrest, D. J.

    1985-01-01

    The photofraction of a 5.1 cm x 2.0 cm bismuth germanate (BGO) scintillator was measured over a gamma-ray energy range of 0.2 to 6.1 MeV. Several methods, used to minimize the effect of room scattering on the measurement, are discussed. These include a gamma-gamma coincidence technique, a beta-gamma coincidence technique, and the use of sources calibrated with a standard 7.6 cm x 7.6 cm sodium iodide scintillator.

  8. Profiling soil water content sensor

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A waveguide-on-access-tube (WOAT) sensor system based on time domain reflectometry (TDR) principles was developed to sense soil water content and bulk electrical conductivity in 20-cm (8 inch) deep layers from the soil surface to depths of 3 m (10 ft) (patent No. 13/404,491 pending). A Cooperative R...

  9. Scenario analysis of Agro-Environment measure adoption for soil erosion protection in Sicilian vineyard (Italy)

    NASA Astrophysics Data System (ADS)

    Novara, Agata; Gristina, Luciano; Fantappiè, Maria; Costantini, Edoardo

    2014-05-01

    Most of the challenges in designing land use policies that address sustainability issues are inherent to the concept of Agro-Environmental Measures (AEM). Researchers, farmers and mainly policy makers need to evaluate the impact of new and existing policies for soil protection. In Europe, farmers commit themselves, for a minimum period of at least five years, to adopt environmentally-friendly farming techniques that undergone legal obligations. On the other hand, farmers receive payments that provide compensation for additional costs and income foregone resulting from applying those environmentally friendly farming practices in line with the stipulations of agri-environment contracts. In this context we prospect scenarios on soil erosion variations in a detailed case study after the application of Agro-Environmental Measures (AEM). The study area is located in the South part of Sicily. In a district area of 11,588 ha, 35.5 % is devoted to vineyard cultivation, 32.2 % is arable land and only 11.1 % cultivated to olive grow. 2416 ha are urbanized areas and other less important crops. A paired-site approach was chosen to study the difference in soil organic carbon stocks after AEM adoption, following criteria based on Conteh (1999) also applied in several research studies. For the purpose of comparison, the members of a paired site were selected to be similar with respect to the type of soil, slope, elevation, and drainage, but not to AEM. The comparisons were made between adjacent patches of land with different AEM, and a known history of land use and management. 100 paired sites (two adjacent plots) were chosen and three soil samples (0-30 cm depth) were collected in each plot (600 soil samples). The rainfall erosivity (R) factor (Mj mm ha-1 hour-1 year-1) was estimated with the formula specifically proposed for Sicily by Ferro and coauthors in 1999. The soil erodibility factor (K, in tons hour MJ-1 mm-1) was mapped on the base of soil texture and soil organic

  10. Climate change effects on soil organic carbon changes in agricultural lands of Spain

    NASA Astrophysics Data System (ADS)

    Álvaro-Fuentes, J.; Easter, M.; Arrúe, J. L.; Cantero-Martínez, C.; Paustian, K.

    2012-04-01

    parameters needed by the system were obtained from the European soil map (1 km x 1 km). Climate change data was produced by the Meteorology State Agency (Ministry of the Environment and Rural and Marine Affairs of Spain) according to two AOGCMs (ECHAM4 and CGCM2) forced by two IPCC emissions scenarios (SRES: A2 and B2). The model predicted an increase in SOC storage in the 0-30 cm soil depth in all the climate change scenarios tested. Under climate change conditions, Spanish agricultural soils could act as potential atmospheric C sinks. However, the adoption of certain management practices could maximize the sequestration of atmospheric CO2.

  11. Rank Stability Analysis of Surface and Profile Soil Moisture

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although several studies have examined the spatial and rank stability of soil moisture at the surface layer (0-5cm) with the purpose of estimating large scale mean soil moisture, the integration of the rank stability of profile (0-60cm) soil moisture has not been fully considered. This research comb...

  12. Microwave remote sensing of soil water content

    NASA Technical Reports Server (NTRS)

    Cihlar, J.; Ulaby, F. T.

    1975-01-01

    Microwave remote sensing of soils to determine water content was considered. A layered water balance model was developed for determining soil water content in the upper zone (top 30 cm), while soil moisture at greater depths and near the surface during the diurnal cycle was studied using experimental measurements. Soil temperature was investigated by means of a simulation model. Based on both models, moisture and temperature profiles of a hypothetical soil were generated and used to compute microwave soil parameters for a clear summer day. The results suggest that, (1) soil moisture in the upper zone can be predicted on a daily basis for 1 cm depth increments, (2) soil temperature presents no problem if surface temperature can be measured with infrared radiometers, and (3) the microwave response of a bare soil is determined primarily by the moisture at and near the surface. An algorithm is proposed for monitoring large areas which combines the water balance and microwave methods.

  13. Effect of Soil Water Potential on Survival of Meloidogyne javanica in Fallow Soil

    PubMed Central

    Towson, A. J.; Apt, W. J.

    1983-01-01

    A natural infestation of Meloidogyne javanica in an aggregated Oxisol declined at an exponential rate when aliquots of the soil were stored for 72 days in polyethylene bags at various soil water potentials (Ψ). Time periods required for reduction in soil infestations by 50% were 2.7, 4.9, 110, 10, and 2.6 days at Ψ of -0.16, -0.30, -1.1, -15, and -92 bars, respectively. In the wetter soils, at Ψ of -0.16, -0.30, and -1.1 bars, the predominant stage recovered was the second-stage larva. In the drier soils, at Ψ of -15 and -92 bars, both eggs and larvae were recovered with neither stage predominating. Incidence of coiled larvae was inversely related to the Ψ value of the soil, a greater incidence occurring in the drier soils. After 15-32 days, percentages of coiled larvae were 13, 27, 55, 65, and 88% in soil at Ψ of -0.17, -0.60, -1.9, -15, and -82 bars, respectively. PMID:19295774

  14. [Pharmacological effects of CM6912 and its main metabolites].

    PubMed

    Morishita, H; Kushiku, K; Furukawa, T; Yamaki, Y; Izawa, M; Shibazaki, Y; Shibata, U

    1985-07-01

    Pharmacodynamic effects of ethyl 7-chloro-2,3-dihydro-5-(2-fluorophenyl)-2-oxo-1H-1,4- benzodiazepine-3-carboxylate (CM6912), a new benzodiazepine derivative, and its main metabolites (CM6913 = M1, CM7116 = M2) on the peripheral systems were investigated in several species of animals. In pentobarbital-anesthetized rabbits, CM6912 and M2 (1 or 5 mg/kg, i.v.) had little effect on blood pressure, heart rate and ECG, but it slightly reduced the respiration rate. M1 decreased the heart rate without affecting respiration, blood pressure and ECG. In conscious rabbits, CM6912 and M2 (1 mg/kg, i.v.) did not affect respiration, blood pressure, heart rate and ECG, but M1 (1 mg/kg, i.v.) increased the heart rate. CM6912 (5 or 30 mg/kg), when administered orally, also increased heart rate. In pentobarbital-anesthetized dogs, CM6912 and its metabolites (5 mg/kg, i.v.) decreased respiration and heart rate without affecting blood pressure and ECG. CM 6912 (5 mg/kg, i.v.) did not affect cardiovascular responses to the carotid occlusion, vagus stimulation, and pre- and post-ganglionic stimulation of cardiac ganglion in anesthetized dogs. CM6912 and its metabolites affected neither the spontaneous contraction nor the heart rate of isolated rabbit atria. These compounds also had no action on isolated aortic strips from rabbits. CM6912 and its metabolites did not affect the muscle tone of isolated guinea pig intestine, and it had no effects on the contractile responses to acetylcholine, histamine, serotonin and barium chloride. In isolated rabbit intestine, CM6912 and M2 slightly reduced the amplitude of contraction, while M1 had no effect. CM6912 and its metabolites did not affect the spontaneous motility of isolated non-pregnant and pregnant rat uteri as well as in situ non-pregnant rat uterus and isolated guinea pig vas deferens, including the contractile response to adrenaline. CM6912 and M2 relaxed isolated guinea pig trachea strips only at high concentrations. CM6912 and its

  15. Soil charcoal as long-term pyrogenic carbon storage in Amazonian seasonal forests.

    PubMed

    Turcios, Maryory M; Jaramillo, Margarita M A; do Vale, José F; Fearnside, Philip M; Barbosa, Reinaldo Imbrozio

    2016-01-01

    Forest fires (paleo + modern) have caused charcoal particles to accumulate in the soil vertical profile in Amazonia. This forest compartment is a long-term carbon reservoir with an important role in global carbon balance. Estimates of stocks remain uncertain in forests that have not been altered by deforestation but that have been impacted by understory fires and selective logging. We estimated the stock of pyrogenic carbon derived from charcoal accumulated in the soil profile of seasonal forest fragments impacted by fire and selective logging in the northern portion of Brazilian Amazonia. Sixty-nine soil cores to 1-m depth were collected in 12 forest fragments of different sizes. Charcoal stocks averaged 3.45 ± 2.17 Mg ha(-1) (2.24 ± 1.41 Mg C ha(-1) ). Pyrogenic carbon was not directly related to the size of the forest fragments. This carbon is equivalent to 1.40% (0.25% to 4.04%) of the carbon stocked in aboveground live tree biomass in these fragments. The vertical distribution of pyrogenic carbon indicates an exponential model, where the 0-30 cm depth range has 60% of the total stored. The total area of Brazil's Amazonian seasonal forests and ecotones not altered by deforestation implies 65-286 Tg of pyrogenic carbon accumulated along the soil vertical profile. This is 1.2-2.3 times the total amount of residual pyrogenic carbon formed by biomass burning worldwide in 1 year. Our analysis suggests that the accumulated charcoal in the soil vertical profile in Amazonian forests is a substantial pyrogenic carbon pool that needs to be considered in global carbon models. PMID:26207816

  16. Carbon Stocks and Soil C Dynamics: an Investigation of C Sequestration Potential in a Eucalyptus grandis Plantation in Hawaii

    NASA Astrophysics Data System (ADS)

    Reeves, M. I.; Crow, S. E.; Yost, R.; Turn, S.

    2011-12-01

    Tropical forests are important for many reasons, one of which is their ability to transfer large quantities of CO2 from the atmosphere to living biomass thereby potentially offsetting climate change. If the biomass is then harvested for commercial use, the stored carbon (C) is released back to the atmosphere. As a result, commercial rotational forestry is generally considered C neutral. However, the growth and harvest of forests also affects the soil C cycle through inputs of below ground biomass in proportion to above ground biomass. With sustainable management practices, soil can be a long-term sink for C, shifting the C balance of the system and providing a climate offset. This study examines the C stocks and dynamics of an E. grandis plantation located in Hawaii. The study has two parts: 1) A snapshot of C resources in the plantation, and 2) An investigation of change in soil C stock and pool size with afforestation. Above ground biomass C was calculated from measurements of the E. grandis trees and ranged from 40-67 Mg C/ha. Below ground biomass C was estimated from published allometric equations and was 16-27 Mg C/ha. 55 preliminary soil cores from 0-30 cm were collected in a 400 m2 plot in the plantation. Strong spatial dependence was observed in a sample variogram constructed from this data, and cumulative organic C in the top 0.4 t ranged from 120-580 Mg C/ha. To identify the effect of E. grandis afforestation on changes in soil C stock and pools, we compared adjacent pastureland and forested plots in a paired design with six sites. The paired plots constrained elevation, climate, and soil series, so that the effects of conversion from pasture to E. grandis plantation could be evaluated. Soil is physically separated into fractions that have different C turnover times: the labile pool which decomposes rapidly, the intermediate (or intra-aggregate) pool which turns over on a decadal scale, and the mineral-associated pool, which can reside in the soil for

  17. Evaluation of CM5 Charges for Condensed-Phase Modeling.

    PubMed

    Vilseck, Jonah Z; Tirado-Rives, Julian; Jorgensen, William L

    2014-07-01

    The recently developed Charge Model 5 (CM5) is tested for its utility in condensed-phase simulations. The CM5 approach, which derives partial atomic charges from Hirshfeld population analyses, provides excellent results for gas-phase dipole moments and is applicable to all elements of the periodic table. Herein, the adequacy of scaled CM5 charges for use in modeling aqueous solutions has been evaluated by computing free energies of hydration (ΔG hyd) for 42 neutral organic molecules via Monte Carlo statistical mechanics. An optimal scaling factor for the CM5 charges was determined to be 1.27, resulting in a mean unsigned error (MUE) of 1.1 kcal/mol for the free energies of hydration. Testing for an additional 20 molecules gave an MUE of 1.3 kcal/mol. The high precision of the results is confirmed by free energy calculations using both sequential perturbations and complete molecular annihilation. Performance for specific functional groups is discussed; sulfur-containing molecules yield the largest errors. In addition, the scaling factor of 1.27 is shown to be appropriate for CM5 charges derived from a variety of density functional methods and basis sets. Though the average errors from the 1.27*CM5 results are only slightly lower than those using 1.14*CM1A charges, the broader applicability and easier access to CM5 charges via the Gaussian program are additional attractive features. The 1.27*CM5 charge model can be used for an enormous variety of applications in conjunction with many fixed-charge force fields and molecular modeling programs. PMID:25061445

  18. Value of the bipolar lead CM5 in electrocardiography.

    PubMed

    Quyyumi, A A; Crake, T; Mockus, L J; Wright, C A; Rickards, A F; Fox, K M

    1986-10-01

    Only bipolar lead recording are available during ambulatory monitoring. Their sensitivity in detecting ST segment changes in relation to standard electrocardiographic leads is not known. The magnitude and direction of ST segment changes in the bipolar lead CM5 were compared with those in standard electrocardiographic leads in patients during exercise testing and percutaneous transluminal coronary angioplasty. Thirty patients with coronary artery disease were studied during exercise tests in which ST segment depression (greater than 0.5 mm) occurred in one or more standard electrocardiographic leads and 13 patients were studied during angioplasty that resulted in ST segment change in one or more leads (I, II, III, V2, V5, and CM5). Lead CM5 was the most sensitive lead (93%) during exercise testing and also showed the greatest magnitude of ST segment change below the isoelectric line in 93% of the patients. Only two patients, one with ST segment elevation in inferior leads and one with changes restricted to septal leads, had no ST segment depression in lead CM5. When ST segment shift from the baseline electrocardiogram was measured the magnitude of depression was greatest in lead CM5 in only 63% of the patients. During angioplasty of the left anterior descending coronary artery, lead CM5 showed ST segment depression in seven patients, ST segment elevation in two, and a biphasic response in one. Two of the three patients with balloon inflation in right coronary artery developed ST segment elevation in lead CM5. Thus lead CM5 is a reliable lead for detecting subendocardial ischaemia experienced during everyday activities in anginal patients. During total occlusion of coronary arteries (as in variant angina or myocardial infarction) lead CM5 commonly shows ST segment depression and changes due to right coronary artery occlusion may not be detected. PMID:3768217

  19. Value of the bipolar lead CM5 in electrocardiography.

    PubMed Central

    Quyyumi, A A; Crake, T; Mockus, L J; Wright, C A; Rickards, A F; Fox, K M

    1986-01-01

    Only bipolar lead recording are available during ambulatory monitoring. Their sensitivity in detecting ST segment changes in relation to standard electrocardiographic leads is not known. The magnitude and direction of ST segment changes in the bipolar lead CM5 were compared with those in standard electrocardiographic leads in patients during exercise testing and percutaneous transluminal coronary angioplasty. Thirty patients with coronary artery disease were studied during exercise tests in which ST segment depression (greater than 0.5 mm) occurred in one or more standard electrocardiographic leads and 13 patients were studied during angioplasty that resulted in ST segment change in one or more leads (I, II, III, V2, V5, and CM5). Lead CM5 was the most sensitive lead (93%) during exercise testing and also showed the greatest magnitude of ST segment change below the isoelectric line in 93% of the patients. Only two patients, one with ST segment elevation in inferior leads and one with changes restricted to septal leads, had no ST segment depression in lead CM5. When ST segment shift from the baseline electrocardiogram was measured the magnitude of depression was greatest in lead CM5 in only 63% of the patients. During angioplasty of the left anterior descending coronary artery, lead CM5 showed ST segment depression in seven patients, ST segment elevation in two, and a biphasic response in one. Two of the three patients with balloon inflation in right coronary artery developed ST segment elevation in lead CM5. Thus lead CM5 is a reliable lead for detecting subendocardial ischaemia experienced during everyday activities in anginal patients. During total occlusion of coronary arteries (as in variant angina or myocardial infarction) lead CM5 commonly shows ST segment depression and changes due to right coronary artery occlusion may not be detected. PMID:3768217

  20. Evaluation of CM5 Charges for Condensed-Phase Modeling

    PubMed Central

    2015-01-01

    The recently developed Charge Model 5 (CM5) is tested for its utility in condensed-phase simulations. The CM5 approach, which derives partial atomic charges from Hirshfeld population analyses, provides excellent results for gas-phase dipole moments and is applicable to all elements of the periodic table. Herein, the adequacy of scaled CM5 charges for use in modeling aqueous solutions has been evaluated by computing free energies of hydration (ΔGhyd) for 42 neutral organic molecules via Monte Carlo statistical mechanics. An optimal scaling factor for the CM5 charges was determined to be 1.27, resulting in a mean unsigned error (MUE) of 1.1 kcal/mol for the free energies of hydration. Testing for an additional 20 molecules gave an MUE of 1.3 kcal/mol. The high precision of the results is confirmed by free energy calculations using both sequential perturbations and complete molecular annihilation. Performance for specific functional groups is discussed; sulfur-containing molecules yield the largest errors. In addition, the scaling factor of 1.27 is shown to be appropriate for CM5 charges derived from a variety of density functional methods and basis sets. Though the average errors from the 1.27*CM5 results are only slightly lower than those using 1.14*CM1A charges, the broader applicability and easier access to CM5 charges via the Gaussian program are additional attractive features. The 1.27*CM5 charge model can be used for an enormous variety of applications in conjunction with many fixed-charge force fields and molecular modeling programs. PMID:25061445

  1. Laboratory Experiment on Electrokinetic Remediation of Soil

    ERIC Educational Resources Information Center

    Elsayed-Ali, Alya H.; Abdel-Fattah, Tarek; Elsayed-Ali, Hani E.

    2011-01-01

    Electrokinetic remediation is a method of decontaminating soil containing heavy metals and polar organic contaminants by passing a direct current through the soil. An undergraduate chemistry laboratory is described to demonstrate electrokinetic remediation of soil contaminated with copper. A 30 cm electrokinetic cell with an applied voltage of 30…

  2. An Infiltration Exercise for Introductory Soil Science

    ERIC Educational Resources Information Center

    Barbarick, K. A.; Ippolito, J. A.; Butters, G.; Sorge, G. M.

    2005-01-01

    One of the largest challenges in teaching introductory soil science is explaining the dynamics of soil infiltration. To aid students in understanding the concept and to further engage them in active learning in the soils laboratory course, we developed an exercise using Decagon Mini-Disk Infiltrometers with a tension head (h[subscript o]) of 2 cm.…

  3. The impact of soil compaction and freezing-thawing cycles on soil structure and yield in Mollisol region of China

    NASA Astrophysics Data System (ADS)

    Wang, Enheng; Zhao, Yusen; Chen, Xiangwei

    2015-04-01

    Agricultural machinery tillage and alternating freezing and thawing are two critical factors associated with soil structure change and accelerates soil erosion in the black soil region of Northeast China. Combining practical machinery operation and natural freeze-thaw cycles with artificial machinery compaction in the field and artificial freeze-thaw cycles in the lab, the plus and minus benefits of machinery tillage, characterization of seasonal freeze-thaw cycles, and their effects on soil structure and yield were studied. Firstly,the effects of machinery type and antecedent water content on soil structure and soil available nutrient were investigated by measuring soil bulk density, soil strength, soil porosity, soil aggregate distribution and stability, and three soil phases. The results showed that: Machinery tillage had positive and negative influence on soil structure, soil in top cultivated layer can be loosened and ameliorated however the subsoil accumulation of compaction was resulted. For heavy and medium machinery, subsoil compaction formed in the soil depth of 41~60cm and 31~40cm, respectively; however during the soil depth of 17.5~30cm under medium machinery operation there was a new plow pan produced because of the depth difference between harvesting and subsoiling. Antecedent water content had a significant effect on soil structure under machinery operations. Higher water antecedent resulted in deeper subsoil compaction at 40cm,which was deeper by 10cm than lower water content and soil compaction accumulation occurred at the first pass under higher water content condition. Besides water content and bulk density, soil organic matter is another key factor for affecting compressive-resilient performance of tillage soil. Secondly, based on the soils sampled from fields of the black soil region, the effects of freeze-thaw cycles on soil structure at different soil depths (0 -- 40 cm, 40 -- 80 cm, 120 -- 160 cm) and size scales (field core sampling

  4. Eight-cm mercury ion thruster system technology

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The technology status of 8 cm diameter electron bombardment ion thrusters is presented. Much of the technology resulting from the 5 cm diameter thruster has been adapted and improved upon to increase the reliability, durability, and efficiency of the 8 cm thruster. Technology discussed includes: dependence of neutralizer tip erosion upon neutralizer flow rate; impregnated and rolled-foil insert cathode performance and life testing; neutralizer position studies; thruster ion beam profile measurements; high voltage pulse ignition; high utilization ion machined accelerator grids; deposition internal and external to the thruster; thruster vectoring systems; thruster cycling life testing and thruster system weights for typical mission applications.

  5. Ion accelerator systems for high power 30 cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    Two and three-grid accelerator systems for high power ion thruster operation were investigated. Two-grid translation tests show that over compensation of the 30 cm thruster SHAG grid set spacing the 30 cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30 cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  6. [Change of Bt protein in soil after growing Bt corns and returning corn straws to soil and its effects on soil nutrients].

    PubMed

    Zeng, Ping; Feng, Yuan-Jiao; Zhang, Wan-Chun; Zhang, Yan-Fei; Dong, Wen-Chao; Wang, Jian-Wu

    2014-07-01

    The spatiotemporal dynamics of Bt protein in soil and the change of soil nutrients in rhizosphere soil, root surface soil and soils at 0-20, 20-40 and 40-60 cm were measured in greenhouse experiments. Two Bt corns, 5422Bt1 and 5422CBCL, and their near isogenic non-Bt variety 5422 were grown for 90 days and the crop residues were retained to soil. Results showed that 1.59 and 2.78 ng x g(-1) Bt protein were detected in the rhizosphere soil with Bt corns 5422Bt1 and 5422CBCL immediately after harvest. However, there were only trace amounts of Bt protein (< 0.5 ng x g(-1)) were detected in root surface soil after 90 days and in bulk soil in the two Bt corn treatments after 30, 60 and 90 days. When corn residues returned to soil, Bt protein declined rapidly within 3 days and only trace amounts of Bt protein were measured after 7 days. There were no sig- nificant differences in organic matter, available nutrient (alkaline hydrolytic N, available P, available K) or total nutrient (total N, total P, total K) in root surface soils and soils at 0-20 cm, 20-40 cm and 40-60 cm among the Bt and non-Bt corns after 90 days. Sixty days after returning crop residues of 5422Btl to soil, the contents of organic matter and total N increased and the content of available K reduced significantly in the 0-20 cm soil depth. There were no significant differences in any other parameter at the 0-20 cm depth, neither for any parameter in the 20-40 cm and 40-60 cm soil depths compared to those in the non-Bt corn 5422 treatment. There were no significant differences in soil nutrient contents in Bt corn 5422CBCL treatment compared to those in non-Bt corn 5422 treatment except that available phosphorus content was reduced in root surface soils, and total P content increased at the 0-20 cm soil depth after 90 days. When crop residues of Bt corn 5422 CBCL were returned to soil, only available P content in the 0-20 cm soil layer was evidently higher compared to the soil receiving crop residues of

  7. Behavior of oxyfluorfen in soils amended with different sources of organic matter. Effects on soil biology.

    PubMed

    Gómez, Isidoro; Rodríguez-Morgado, Bruno; Parrado, Juan; García, Carlos; Hernández, Teresa; Tejada, Manuel

    2014-05-30

    We performed a laboratory study on the effect of oxyfluorfen at a rate of 4lha(-1) on biological properties of a soil amended with four organic wastes (two biostimulants/biofertilizers, obtained from rice bran, RB1 and RB2; municipal solid waste, MSW; and sheep manure, SM). Soil was mixed with SM at a rate of 1%, MSW at a rate of 0.52%, RB1 at a rate of 0.39% and RB2 at a rate of 0.30%, in order to apply the same amount of organic matter to the soil. The enzymatic activities and microbial community in the soil were determined during the incubation times. The application of RB1 and RB2 to soil without oxyfluorfen increased the enzymatic activities and biodiversity, peaking at day 10 of the incubation period. This stimulation was higher in the soil amended with RB2 than in that amended with RB1. In SM and CF-amended soils, the stimulation of enzymatic activities and soil biodiversity increased during the experiment. The application of herbicide in organic-amended soils decreased the inhibition of soil enzymatic activities and soil biodiversity. Possibly the low molecular weight protein content easily assimilated by soil microorganisms and the higher fat content in the biostimulants/biofertilizers are responsible for the lower inhibition of these soil biological properties. PMID:24742665

  8. Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change.

    PubMed

    Viscarra Rossel, Raphael A; Webster, Richard; Bui, Elisabeth N; Baldock, Jeff A

    2014-09-01

    We can effectively monitor soil condition-and develop sound policies to offset the emissions of greenhouse gases-only with accurate data from which to define baselines. Currently, estimates of soil organic C for countries or continents are either unavailable or largely uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of organic C in the soil of Australia. We assembled and harmonized data from several sources to produce the most comprehensive set of data on the current stock of organic C in soil of the continent. Using them, we have produced a fine spatial resolution baseline map of organic C at the continental scale. We describe how we made it by combining the bootstrap, a decision tree with piecewise regression on environmental variables and geostatistical modelling of residuals. Values of stock were predicted at the nodes of a 3-arc-sec (approximately 90 m) grid and mapped together with their uncertainties. We then calculated baselines of soil organic C storage over the whole of Australia, its states and territories, and regions that define bioclimatic zones, vegetation classes and land use. The average amount of organic C in Australian topsoil is estimated to be 29.7 t ha(-1) with 95% confidence limits of 22.6 and 37.9 t ha(-1) . The total stock of organic C in the 0-30 cm layer of soil for the continent is 24.97 Gt with 95% confidence limits of 19.04 and 31.83 Gt. This represents approximately 3.5% of the total stock in the upper 30 cm of soil worldwide. Australia occupies 5.2% of the global land area, so the total organic C stock of Australian soil makes an important contribution to the global carbon cycle, and it provides a significant potential for sequestration. As the most reliable approximation of the stock of organic C in Australian soil in 2010, our estimates have important applications. They could support

  9. Developing a Perceptual Model of Streamflow Generation From Spatially-Distributed Soil Moisture Data: Experiences in an Experimental NZ Catchment

    NASA Astrophysics Data System (ADS)

    Srinivasan, M.; McMillan, H. K.; Clark, M. P.; Goodrich, D. C.; Duncan, M.; Woods, R.; Western, A.

    2008-12-01

    Hydrologic model simulations can only be deemed credible if the model structure is consistent with current understanding of hydrological processes. The necessary steps in building a numerical model are therefore to develop a perceptual model of how the catchment functions and a conceptual model that provides an overview of the major storages and fluxes of water in the catchment. This development can be greatly aided by spatially-distributed measurements of internal catchment behaviour over time, in addition to the integrated response provided by streamflow data. Such a model building exercise needs data at different spatial and temporal scales to be brought together to form a coherent understanding of catchment processes. This presentation outlines our experiences in interpreting streamflow and multi-depth soil moisture time-series data in developing a perceptual model of streamflow generation for two headwater catchments within the experimental Mahurangi catchment, North Island, New Zealand. Soil moisture measurements were made at six locations, spatially distributed across the subcatchments, and at two soil depths - surface (0-30 cm) and subsurface (30-45 cm; top of the B-horizon). Measurements were made at 30 min intervals over a period of 34 months. Results show that the surface soil moisture responses were influenced by event rainfall input and seasonality in evapotranspiration rates, and were strongly related to stormflows and baseflows. The subsurface soil moisture followed an annual cycle, with little correlation to event rainfall; and surprisingly did not appear to be related to streamflow. The subsurface soil moisture data did not indicate the presence of a perched water table or a saturated subsurface layer. However the slow variation of soil moisture in this layer suggested that very little moisture was lost to evaporation or drainage. There appears to be a lack of connectivity between surface and subsurface soil moisture zones across the landscape

  10. Orion Landing Simulation Eight Soil Model Comparison

    NASA Technical Reports Server (NTRS)

    Mark, Stephen D.

    2009-01-01

    LS-DYNA finite element simulations of a rigid Orion Crew Module (CM) were used to investigate the CM impact behavior on eight different soil models. Ten different landing conditions, characterized by the combination of CM vertical and horizontal velocity, hang angle, and roll angle were simulated on the eight different soils. The CM center of gravity accelerations, pitch angle, kinetic energy, and soil contact forces were the outputs of interest. The simulation results are presented, with comparisons of the CM behavior on the different soils. The soils analyzed in this study can be roughly categorized as soft, medium, or hard, according to the CM accelerations that occur when landing on them. The soft group is comprised of the Carson Sink Wet soil and the Kennedy Space Center (KSC) Low Density Dry Sand. The medium group includes Carson Sink Dry, the KSC High Density In-Situ Moisture Sand and High Density Flooded Sand, and Cuddeback B. The hard soils are Cuddeback A and the Gantry Unwashed Sand. The softer soils were found to produce lower peak accelerations, have more stable pitch behavior, and to be less sensitive to the landing conditions. This investigation found that the Cuddeback A soil produced the highest peak accelerations and worst stability conditions, and that the best landing performance was achieved on the KSC Low Density Dry Sand.

  11. Electric field dependence of nonlinearity parameters and third order elastic constants of 0.70Pb(Mg1∕3Nb2∕3)O3–0.30PbTiO3 single crystal

    PubMed Central

    Liu, Xiaozhou; Zhang, Shujun; Luo, Jun; Shrout, Thomas R.; Cao, Wenwu

    2010-01-01

    Through second harmonic measurements, the ultrasonic nonlinearity parameters of [001]c and [111]c polarized 0.70Pb(Mg1∕3Nb2∕3)O3–0.30PbTiO3(PMN–0.3PT) single crystals have been measured as a function of bias electric field. It was found that the nonlinearity parameter increases almost linearly with field at low field but shows a drastic increase near the coercive field. The [111]c polarized single domain crystal has much smaller nonlinearity parameter than that of the [001]c polarized multidomain crystal. Based on effective symmetries of these crystals, we were able to derive the field dependence of several third order elastic constants, which are important parameters for high field applications. PMID:20198132

  12. An investigation on the microstructures and magnetic properties of the Sr0.35-xBaxCa0.30La0.35Fe11.71Co0.29O19 hexaferrites

    NASA Astrophysics Data System (ADS)

    Yang, Yujie; Liu, Xiansong

    2014-11-01

    M-type hexaferrite Sr0.35-xBaxCa0.30La0.35Fe11.71Co0.29O19 (0≤x≤0.35) magnetic powders and magnets were prepared by the solid-state reaction. The phase compositions of the magnetic powders were investigated by X-ray diffraction. X-ray diffraction patterns show that the hexagonal single phase is obtained in all samples. The micrographs of the magnets were observed by a field emission scanning electron microscopy. All magnets have formed hexagonal structures and the particles are distributed evenly. Magnetic properties of the magnets were measured by a magnetic properties test instrument. The remanence, intrinsic coercivity, magnetic induction coercivity and maximum energy product of the magnets continuously decrease with increasing barium content (x).

  13. Extrinsic mechanism for giant dielectric response in Ba{sub 0.70}Sr{sub 0.30}(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} ceramic

    SciTech Connect

    Patel, Piyush Kumar Yadav, K. L. Durgesh

    2014-04-24

    To obtain the high dielectric constant, the effect of sintering process on the electrical properties of Ba{sub 0.70}Sr{sub 0.30}(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} ceramics were investigated. X-ray diffraction pattern of the samples at room temperature shows a monoclinic structure. Microstructure analysis shows well-grown and dense microstructure in all the samples. We found giant dielectric constant (∼3.59 × 10{sup 5}) with low dielectric loss (∼0.49) at room temperature for 2 hr sintered sample at 1250 °C. The extrinsic phenomena like interfacial polarization due to space charge accumulation at grain boundaries are discussed.

  14. Electromechanical coupling coefficient of 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal resonator with arbitrary aspect ratio

    NASA Astrophysics Data System (ADS)

    Huang, Naixing; Zhang, Rui; Cao, Wenwu

    2007-09-01

    Based on mode coupling theory and the fundamental energy ratio definition of the electromechanical coupling coefficient, a unified formula has been derived to calculate the effective electromechanical coupling coefficient keff of 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 (PMN-30%PT) ferroelectric single crystal cylindrical resonator with arbitrary aspect ratio. The keff dependence on resonator aspect ratio of PMN-30%PT crystal shows similar characteristics as that of the conventional piezoelectric ceramics Pb(ZrxTi1-x)O3 (PZT). However, compared to PZT-5 ceramics, PMN-30%PT single crystal has a smaller aspect ratio where the keff changes dramatically and there is also a stronger coupling between thickness and radial modes causing much larger mode splitting.

  15. Mechanisms of soil degradation and consequences for carbon stocks on Tibetan grasslands

    NASA Astrophysics Data System (ADS)

    Kuzyakov, Yakov; Schleuss, Per-Marten; Miehe, Georg; Heitkamp, Felix; Sebeer, Elke; Spielvogel, Sandra; Xu, Xingliang; Guggenberger, Georg

    2016-04-01

    Tibetan grasslands provide tremendous sinks for carbon (C) and represent important grazing ground. Strong degradation - the destroying the upper root-mat/soil horizon of Kobresia pastures, has dramatic consequences for soil organic carbon (SOC) and nutrient storage. To demonstrate specific degradation patterns and elucidate mechanisms, as well as to assess consequences for SOC storage, we investigated a sequence of six degradation stages common over the whole Kobresia ecosystem. The soil degradation sequence consists of following mechanisms: Overgrazing and trampling by livestock provide the prerequisite for grassland degradation as both (a) cause plant dying, (b) reduce grassland recovery and (c) destroy protective Kobresia root-mats. These anthropogenic induced processes are amplified by naturally occurring degradation in harsh climate. The frequently repeated soil moisture and temperature fluctuations induce volume changes and tensions leading to polygonal cracking of the root mats. Then the plants die and erosion gradually extend the surface cracks. Soil erosion cause a high SOC loss from the upper horizons (0-10 cm: ~5.1 kg C m-2), whereas SOC loss beneath the surface cracks is caused by both, decreasing root C-input and SOC mineralization (SOC losses by mineralization: ~2.5 kg C m-2). Root biomass decreases with degradation and indicated lower C input. The negative δ13C shift of SOC reflects intensive decomposition and corresponds to a relative enrichment of 13C depleted lignin components. We conclude that the combined effects of overgrazing and harsh climate reduce root C input, increase SOC decomposition and initiate erosion leading to SOC loss up to 70% of intact soil (0-30 cm: ~7.6 kg C m-2). Consequently, a high amount of C is released back to the atmosphere as CO2, or is deposited in depressions and river beds creating a potential source of N2O and CH4. Concluding, anthropogenically induced overgrazing makes the Kobresia root-mat sensitive to natural

  16. Characterization of Luminescent Minerals in CM2 Chondrite (Jbilet Winselwan)

    NASA Astrophysics Data System (ADS)

    Kiku, Y. K.; Ohgo, S. O.; Nishido, H. N.

    2014-09-01

    We have characterized luminescent minerals of forsterite, diopside and spinel in the CM2 chondrite (Jbilet Winselwan) using SEM-CL and to discuss the formation of the luminescent minerals under aqueous conditions.

  17. Benchmarking and performance analysis of the CM-2. [SIMD computer

    NASA Technical Reports Server (NTRS)

    Myers, David W.; Adams, George B., II

    1988-01-01

    A suite of benchmarking routines testing communication, basic arithmetic operations, and selected kernel algorithms written in LISP and PARIS was developed for the CM-2. Experiment runs are automated via a software framework that sequences individual tests, allowing for unattended overnight operation. Multiple measurements are made and treated statistically to generate well-characterized results from the noisy values given by cm:time. The results obtained provide a comparison with similar, but less extensive, testing done on a CM-1. Tests were chosen to aid the algorithmist in constructing fast, efficient, and correct code on the CM-2, as well as gain insight into what performance criteria are needed when evaluating parallel processing machines.

  18. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum.

    PubMed

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  19. CmWRKY15 Facilitates Alternaria tenuissima Infection of Chrysanthemum

    PubMed Central

    Fan, Qingqing; Song, Aiping; Xin, Jingjing; Chen, Sumei; Jiang, Jiafu; Wang, Yinjie; Li, Xiran; Chen, Fadi

    2015-01-01

    Abscisic acid (ABA) has an important role in the responses of plants to pathogens due to its ability to induce stomatal closure and interact with salicylic acid (SA) and jasmonic acid (JA). WRKY transcription factors serve as antagonistic or synergistic regulators in the response of plants to a variety of pathogens. Here, we demonstrated that CmWRKY15, a group IIa WRKY family member, was not transcriptionally activated in yeast cells. Subcellular localization experiments in which onion epidermal cells were transiently transfected with CmWRKY15 indicated that CmWRKY15 localized to the nucleus in vivo. The expression of CmWRKY15 could be markedly induced by the presence of Alternaria tenuissima inoculum in chrysanthemum. Furthermore, the disease severity index (DSI) data of CmWRKY15-overexpressing plants indicated that CmWRKY15 overexpression enhanced the susceptibility of chrysanthemum to A. tenuissima infection compared to controls. To illustrate the mechanisms by which CmWRKY15 regulates the response to A. tenuissima inoculation, the expression levels of ABA-responsive and ABA signaling genes, such as ABF4, ABI4, ABI5, MYB2, RAB18, DREB1A, DREB2A, PYL2, PP2C, RCAR1, SnRK2.2, SnRK2.3, NCED3A, NCED3B, GTG1, AKT1, AKT2, KAT1, KAT2, and KC1were compared between transgenic plants and controls. In summary, our data suggest that CmWRKY15 might facilitate A. tenuissima infection by antagonistically regulating the expression of ABA-responsive genes and genes involved in ABA signaling, either directly or indirectly. PMID:26600125

  20. [Effect of Biochar Application on Soil Aggregates Distribution and Moisture Retention in Orchard Soil].

    PubMed

    An, Yan; Ji, Qiang; Zhao, Shi-xiang; Wang, Xu-dong

    2016-01-15

    Applying biochar to soil has been considered to be one of the important practices in improving soil properties and increasing carbon sequestration. In order to investigate the effects of biochar application on soil aggregates distribution and its organic matter content and soil moisture constant in different size aggregates, various particle-size fractions of soil aggregates were obtained with the dry-screening method. The results showed that, compared to the treatment without biochar (CK), the application of biochar reduced the mass content of 5-8 mm and < 0.25 mm soil aggregates at 0-10 cm soil horizon, while increased the content of 1-2 mm and 2-5 mm soil aggregates at this horizon, and the content of 1-2 mm aggregates significantly increased along with the rates of biochar application. The mean diameter of soil aggregates was reduced by biochar application at 0-10 cm soil horizon. However, the effect of biochar application on the mean diameter of soil aggregates at 10-20 cm soil horizon was not significant. Compared to CK, biochar application significantly increased soil organic carbon content in aggregates, especially in 1-2 mm aggregates which was increased by > 70% compared to CK. Both the water holding capacity and soil porosity were significantly increased by biochar application. Furthermore, the neutral biochar was more effective than alkaline biochar in increasing soil moisture. PMID:27078970

  1. A new baseline of organic carbon stock in European agricultural soils using a modelling approach.

    PubMed

    Lugato, Emanuele; Panagos, Panos; Bampa, Francesca; Jones, Arwyn; Montanarella, Luca

    2014-01-01

    Proposed European policy in the agricultural sector will place higher emphasis on soil organic carbon (SOC), both as an indicator of soil quality and as a means to offset CO2 emissions through soil carbon (C) sequestration. Despite detailed national SOC data sets in several European Union (EU) Member States, a consistent C stock estimation at EU scale remains problematic. Data are often not directly comparable, different methods have been used to obtain values (e.g. sampling, laboratory analysis) and access may be restricted. Therefore, any evolution of EU policies on C accounting and sequestration may be constrained by a lack of an accurate SOC estimation and the availability of tools to carry out scenario analysis, especially for agricultural soils. In this context, a comprehensive model platform was established at a pan-European scale (EU + Serbia, Bosnia and Herzegovina, Croatia, Montenegro, Albania, Former Yugoslav Republic of Macedonia and Norway) using the agro-ecosystem SOC model CENTURY. Almost 164 000 combinations of soil-climate-land use were computed, including the main arable crops, orchards and pasture. The model was implemented with the main management practices (e.g. irrigation, mineral and organic fertilization, tillage) derived from official statistics. The model results were tested against inventories from the European Environment and Observation Network (EIONET) and approximately 20 000 soil samples from the 2009 LUCAS survey, a monitoring project aiming at producing the first coherent, comprehensive and harmonized top-soil data set of the EU based on harmonized sampling and analytical methods. The CENTURY model estimation of the current 0-30 cm SOC stock of agricultural soils was 17.63 Gt; the model uncertainty estimation was below 36% in half of the NUTS2 regions considered. The model predicted an overall increase of this pool according to different climate-emission scenarios up to 2100, with C loss in the south and east of the area

  2. Land surface feedbacks and climate change over South America as projected by RegCM4

    NASA Astrophysics Data System (ADS)

    Llopart, Marta; da Rocha, Rosmeri; Coppola, Erika; Giorgi, Filippo; Cuadra, Santiago

    2013-04-01

    soil moisture feedback on precipitation is evaluated too by mean of a statistical approach. The RegCM-CLM simulations have a common feature and they show a similar behavior when the future changes are investigated. The RegCM-BATS shows a different soil moisture feedback picture. Of course this can be explained by the differences in the two land-surface schemes and in the precipitation change signal that comes out from the two sets of simulations.

  3. Chondrules in the Murray CM2 meteorite and compositional differences between CM-CO and ordinary chondrite chondrules

    NASA Astrophysics Data System (ADS)

    Rubin, A. E.; Wasson, J. T.

    1986-02-01

    Thirteen of the least aqueously altered chondrules in Murray (CM2) were analyzed for bulk compositions, by means of a broad beam electron microprobe, to explore the compositional differences between the CM-CO, and the ordinary chondrite OC chondrules. The CO chondrules are richer in refractory lithophiles and poorer in Cr, Mn, and volatile lithophiles than the OC chondrules; much lower refractory lithophile abundances in CM chondrules resulted from aqueous alteration. Evidence is found for two important lithophile precursor components of CM-CO chondrite chondrules: (1) pyroxene- and refractory-rich, FeO-poor, and (2) olivine-rich, refractoryand FeO-poor. It is suggested that the pyroxene- and refractory-rich, FeO-poor lithophile precursor component has formed by an incomplete evaporation of presolar silicates that brought these materials into the enstatite stability field.

  4. Soil CO₂ dynamics in a tree island soil of the Pantanal: the role of soil water potential.

    PubMed

    Johnson, Mark S; Couto, Eduardo Guimarães; Pinto, Osvaldo B; Milesi, Juliana; Santos Amorim, Ricardo S; Messias, Indira A M; Biudes, Marcelo Sacardi

    2013-01-01

    The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO₂ research has been conducted in this region. We evaluated soil CO₂ dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO₂ concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO₂ efflux and related environmental parameters. Soil CO₂ efflux during the study averaged 3.53 µmol CO₂ m⁻² s⁻¹, and was equivalent to an annual soil respiration of 1220 g C m⁻² y⁻¹. This efflux value, integrated over a year, is comparable to soil C stocks for 0-20 cm. Soil water potential was the measured parameter most strongly associated with soil CO₂ concentrations, with high CO₂ values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO₂ efflux from the tree island soil, with soil CO₂ dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO₂ efflux from soil. The annual flood arrives later, and saturates soil from below. While CO₂ concentrations in soil grew very high under both wetting mechanisms, the change in soil CO₂ efflux was only significant when soils were wet from above. PMID:23762259

  5. Soil CO2 Dynamics in a Tree Island Soil of the Pantanal: The Role of Soil Water Potential

    PubMed Central

    Johnson, Mark S.; Couto, Eduardo Guimarães; Pinto Jr, Osvaldo B.; Milesi, Juliana; Santos Amorim, Ricardo S.; Messias, Indira A. M.; Biudes, Marcelo Sacardi

    2013-01-01

    The Pantanal is a biodiversity hotspot comprised of a mosaic of landforms that differ in vegetative assemblages and flooding dynamics. Tree islands provide refuge for terrestrial fauna during the flooding period and are particularly important to the regional ecosystem structure. Little soil CO2 research has been conducted in this region. We evaluated soil CO2 dynamics in relation to primary controlling environmental parameters (soil temperature and soil water). Soil respiration was computed using the gradient method using in situ infrared gas analyzers to directly measure CO2 concentration within the soil profile. Due to the cost of the sensors and associated equipment, this study was unreplicated. Rather, we focus on the temporal relationships between soil CO2 efflux and related environmental parameters. Soil CO2 efflux during the study averaged 3.53 µmol CO2 m−2 s−1, and was equivalent to an annual soil respiration of 1220 g C m−2 y−1. This efflux value, integrated over a year, is comparable to soil C stocks for 0–20 cm. Soil water potential was the measured parameter most strongly associated with soil CO2 concentrations, with high CO2 values observed only once soil water potential at the 10 cm depth approached zero. This relationship was exhibited across a spectrum of timescales and was found to be significant at a daily timescale across all seasons using conditional nonparametric spectral Granger causality analysis. Hydrology plays a significant role in controlling CO2 efflux from the tree island soil, with soil CO2 dynamics differing by wetting mechanism. During the wet-up period, direct precipitation infiltrates soil from above and results in pulses of CO2 efflux from soil. The annual flood arrives later, and saturates soil from below. While CO2 concentrations in soil grew very high under both wetting mechanisms, the change in soil CO2 efflux was only significant when soils were wet from above. PMID:23762259

  6. [Effect of fertilization levels on soil microorganism amount and soil enzyme activities].

    PubMed

    Wang, Wei-Ling; Du, Jun-Bo; Xu, Fu-Li; Zhang, Xiao-Hu

    2013-11-01

    Field experiments were conducted in Shangluo pharmaceutical base in Shaanxi province to study the effect of nitrogen, phosphorus and potassium in different fertilization levels on Platycodon grandiflorum soil microorganism and activities of soil enzyme, using three-factor D-saturation optimal design with random block design. The results showed that N0P2K2, N2P2K0, N3P1K3 and N3P3K1 increased the amount of bacteria in 0-20 cm of soil compared with N0P0K0 by 144.34%, 39.25%, 37.17%, 53.58%, respectively. The amount of bacteria in 2040 cm of soil of N3P1K3 increased by 163.77%, N0P0K3 increased the amount of soil actinomycetes significantly by 192.11%, while other treatments had no significant effect. N2P0K2 and N3P1K3 increased the amounts of fungus significantly in 0-20 cm of soil compared with N0P0K0, increased by 35.27% and 92.21%, respectively. N3P0K0 increased the amounts of fungus significantly in 20-40 cm of soil by 165.35%, while other treatments had no significant effect. All treatments decrease soil catalase activity significantly in 0-20 cm of soil except for N2P0K2, and while N2P2K0 and NPK increased catalase activity significantly in 2040 cm of soil. Fertilization regime increased invertase activity significantly in 2040 cm of soil, and decreased phosphatase activity inordinately in 0-20 cm of soil, while increased phosphatase activity in 2040 cm of soil other than N1P3K3. N3P0K0, N0P0K3, N2P0K2, N2P2K0 and NPK increased soil urease activity significantly in 0-20 cm of soil compared with N0P0K0 by 18.22%, 14.87%,17.84%, 27.88%, 24.54%, respectively. Fertilization regime increased soil urease activity significantly in 2040 cm of soil other than N0P2K2. PMID:24558863

  7. The assessment of treated wastewater quality and the effects of mid-term irrigation on soil physical and chemical properties (case study: Bandargaz-treated wastewater)

    NASA Astrophysics Data System (ADS)

    Kaboosi, Kami

    2016-05-01

    This study was conducted to investigate the characteristics of inflow and outflow wastewater of the Bandargaz wastewater treatment plant on the basis of the data collection of operation period and the samples taken during the study. Also the effects of mid-term use of the wastewater for irrigation (from 2005 to 2013) on soil physical and chemical characteristics were studied. For this purpose, 4 samples were taken from the inflow and outflow wastewater and 25 quality parameters were measured. Also, the four soil samples from a depth of 0-30 cm of two rice field irrigated with wastewater in the beginning and middle of the planting season and two samples from one adjacent rice field irrigated with fresh water were collected and their chemical and physical characteristics were determined. Average of electrical conductivity, total dissolved solids, sodium adsorption ratio, chemical oxygen demand and 5 days biochemical oxygen demand in treated wastewater were 1.35 dS/m, 707 ppm, 0.93, 80 ppm and 40 ppm, respectively. Results showed that although some restrictions exist about chlorine and bicarbonate, the treated wastewater is suitable for irrigation based on national and international standards and criteria. In comparison with fresh water, the mid-term use of wastewater caused a little increase of soil salinity. However, it did not lead to increase of soil salinity beyond rice salinity threshold. Also, there were no restrictions on soil in the aspect of salinity and sodium hazard on the basis of many irrigated soil classifications. In comparison with fresh water, the mid-term use of wastewater caused the increase of total N, absorbable P and absorbable K in soil due to high concentration of those elements in treated wastewater.

  8. Determining the relative extent of alteration in CM chondrites

    NASA Technical Reports Server (NTRS)

    Browning, Lauren B.; Mcsween, Harry Y., Jr.; Zolensky, Michael

    1993-01-01

    The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

  9. Determining the relative extent of alteration in CM chondrites

    NASA Astrophysics Data System (ADS)

    Browning, Lauren B.; McSween, Harry Y., Jr.; Zolensky, Michael

    1993-03-01

    The aqueous alteration of CM chondrites provides a record of the processes attending the earliest stages of parent body evolution. However, resolving the alteration pathways of chondritic evolution requires a means for distinguishing the relative extent of alteration that individual samples have experienced. Three new indices for gauging the relative degree of alteration in CM chondrites based on modal and compositional analyses of 7 CM falls were proposed. The proposed alteration parameters are consistent with the basic tenets of several previous models and correlate with additional indices to produce an integrated method for determining the relative extent of alteration. The model predicts the following order of progressive alteration: Murchison (MC) is less than or equal to Bells (BL) is less than Murray (MY) is less than Cochabamba (CC) is less than Mighei (MI) is less than Nogoya (NG) is less than or equal to Cold Bokkeveld (CB). The broad range of CM phyllosilicate compositions observed within individual meteorites is fundamental to the characterization of the aqueous alteration process. Chemical analyses of CM phyllosilicates suggest that these phases became systematically enriched in Mg and depleted in Fe with increasing alteration.

  10. Advancing precision cosmology with 21 cm intensity mapping

    NASA Astrophysics Data System (ADS)

    Masui, Kiyoshi Wesley

    In this thesis we make progress toward establishing the observational method of 21 cm intensity mapping as a sensitive and efficient method for mapping the large-scale structure of the Universe. In Part I we undertake theoretical studies to better understand the potential of intensity mapping. This includes forecasting the ability of intensity mapping experiments to constrain alternative explanations to dark energy for the Universe's accelerated expansion. We also considered how 21 cm observations of the neutral gas in the early Universe (after recombination but before reionization) could be used to detect primordial gravity waves, thus providing a window into cosmological inflation. Finally we showed that scientifically interesting measurements could in principle be performed using intensity mapping in the near term, using existing telescopes in pilot surveys or prototypes for larger dedicated surveys. Part II describes observational efforts to perform some of the first measurements using 21 cm intensity mapping. We develop a general data analysis pipeline for analyzing intensity mapping data from single dish radio telescopes. We then apply the pipeline to observations using the Green Bank Telescope. By cross-correlating the intensity mapping survey with a traditional galaxy redshift survey we put a lower bound on the amplitude of the 21 cm signal. The auto-correlation provides an upper bound on the signal amplitude and we thus constrain the signal from both above and below. This pilot survey represents a pioneering effort in establishing 21 cm intensity mapping as a probe of the Universe.

  11. CM Carbonaceous Chondrite Lithologies and Their Space Exposure Ages

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael; Gregory, Timothy; Takenouchi, Atsushi; Nishiizumi, Kunihiko; Trieman, Alan; Berger, Eve; Le, Loan; Fagan, Amy; Velbel, Michael; Imae, Naoya; Yamaguchi, Akira

    2015-01-01

    The CMs are the most commonly falling C chondrites, and therefore may be a major component of C-class asteroids, the targets of several current and future space missions. Previous work [1] has concluded that CM chondrites fall into at least four distinct cosmic ray space exposure (CRE) age groups (0.1 million years, 0.2 million years, 0.6 million years and greater than 2.0 million years), an unusually large number, but the meaning of these groupings is unclear. It is possible that these meteorites came from different parent bodies which broke up at different times, or instead came from the same parent body which underwent multiple break-up events, or a combination of these scenarios, or something else entirely. The objective of this study is to investigate the diversity of lithologies which make up CM chondrites, in order to determine whether the different exposure ages correspond to specific, different CM lithologies, which permit us to constrain the history of the CM parent body(ies). We have already reported significant petrographic differences among CM chondrites [2-4]. We report here our new results.

  12. The Low-Mass Double-Lined Eclipsing Binary CM Draconis

    NASA Astrophysics Data System (ADS)

    Metcalfe, Travis S.; Mathieu, Robert D.; Latham, David W.; Torres, Guillermo

    1994-12-01

    CM Draconis is the least massive main-sequence eclipsing double-lined spectroscopic binary currently known. Consequently, this system offers a unique opportunity to test stellar structure models near the bottom of the main sequence. The orbital solution of Lacy (1977) established the masses and radii of the two components with uncertainties of a few percent, but these errors are too large to distinguish between competing models. We present a new double-lined orbital solution based on 233 echelle spectra obtained with the CfA Digital Speedometers over the past ten years. Radial velocities for both components were determined using TODCOR, a two-dimensional correlation technique developed by Zucker and Mazeh (1994). We derive individual masses of MA = 0.231 +/- 0.002 and MB = 0.214 +/- 0.001 Msun and a mass ratio of q = 0.926 +/- 0.004. When plotted on a mass-radius diagram using the radii derived by Lacy, the slope defined by the two components of CM Draconis agrees well with the model slopes. The ability to distinguish between models is limited by the uncertainties in the radii and the metal abundance. Following the analysis of Paczynski and Sienkiewicz (1984) we derive bulk helium abundances for the two components of YA = 0.31 and YB = 0.30. The uncertainty is these helium abundances relative to each other is nominally +/- 0.02 and depends primarily on the uncertainty in the ratios of the masses and radii. The uncertainty in the absolute helium abundance is considerably larger and depends on the uncertainty in the absolute masses and radii, the parallax, bolometric correction, age, metallicity, and details of the stellar structure models (such as nuclear cross sections). The uncertainty in the absolute helium abundance is nominally +/- 0.05, but improved determinations of the radii, parallax, and bolometric correction are especially needed to confirm and improve this uncertainty. CM Draconis appears to be a member of Population II. Thus, it may be able to provide a

  13. CM-2 Environmental / Modal Testing of Spacehab Racks

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.; Farkas, Michael A.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that launches on Shuttle mission STS 107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the Shuttle.

  14. CM-2 Environmental/Modal Testing of SPACEHAB Racks

    NASA Technical Reports Server (NTRS)

    McNelis, Mark E.; Goodnight, Thomas W.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.

  15. Differentiating CDM and baryon isocurvature models with 21 cm fluctuations

    SciTech Connect

    Kawasaki, Masahiro; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: sekiguti@icrr.u-tokyo.ac.jp

    2011-10-01

    We discuss how one can discriminate models with cold dark matter (CDM) and baryon isocurvature fluctuations. Although current observations such as cosmic microwave background (CMB) can severely constrain the fraction of such isocurvature modes in the total density fluctuations, CMB cannot differentiate CDM and baryon ones by the shapes of their power spectra. However, the evolution of CDM and baryon density fluctuations are different for each model, thus it would be possible to discriminate those isocurvature modes by extracting information on the fluctuations of CDM/baryon itself. We discuss that observations of 21 cm fluctuations can in principle differentiate these modes and demonstrate to what extent we can distinguish them with future 21 cm surveys. We show that, when the isocurvature mode has a large blue-tilted initial spectrum, 21 cm surveys can clearly probe the difference.

  16. Ion accelerator systems for high power 30-cm thruster operation

    NASA Technical Reports Server (NTRS)

    Aston, G.

    1982-01-01

    An investigation of two- and three-grid accelerator systems for high power ion thruster operation has been performed. Two-grid translation tests show that overcompensation of the 30-cm thruster SHAG (Small Hole Accelerator Grid) leads to a premature impingement limit. By better matching the SHAG grid set spacing to the 30-cm thruster radial plasma density variation and by incorporating grid compensation only sufficient to maintain grid hole axial alignment, it is shown that beam current gains as large as 50% can be realized. Three-grid translation tests performed with a simulated 30-cm thruster discharge chamber show that substantial beamlet steering can be reliably affected by decelerator grid translation only, at net-to-total voltage ratios as low as 0.05.

  17. A model for sunspot associated emission at 6 cm wavelength

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Kundu, M. R.; Lantos, P.

    1980-01-01

    Two-dimensional maps of total intensity and circular polarization of a sunspot region at 6 cm have been calculated using a simple model for the chromosphere-corona transition region and observations of the longitudinal component of the photospheric magnetic field. The calculations are in good agreement with the high resolution observations of the same sunspot region at 6 cm, obtained with the Westerbork Synthesis Radio Telescope. It is shown that the 6 cm radiation is predominantly due to gyroresonance absorption process at the second and third harmonics of the gyrofrequency (H = 900-600 G). Estimates of the conductive flux and the electron density in the transition region above the sunspot are also given.

  18. VLA observations of Uranus at 1. 3-20 cm

    SciTech Connect

    De Pater, I.; Gulkis, S.

    1988-08-01

    Observations of Uranus, obtained with resolution 0.5-1.2 arcsec at wavelengths 1.3, 2, 6, and 20 cm using the A and B configurations of the VLA in June-July 1982, October 1983, and February 1984, are reported. The disk-averaged brightness temperatures (DABTs) are determined by model fitting, and the results are presented in extensive graphs and contour maps and characterized in detail. Findings discussed include: (1) an overall spectrum which is relatively flat above 6 cm, (2) 1.3-6-cm brightness which is concentrated nearer to the pole than to the subsolar point, and (3) small changes in DABT from 1982 to 1983/1984 (consistent with an explanation based on a pole-equator temperature gradient). 16 references.

  19. Precise measurements of primordial power spectrum with 21 cm fluctuations

    SciTech Connect

    Kohri, Kazunori; Oyama, Yoshihiko; Sekiguchi, Toyokazu; Takahashi, Tomo E-mail: oyamayo@post.kek.jp E-mail: tomot@cc.saga-u.ac.jp

    2013-10-01

    We discuss the issue of how precisely we can measure the primordial power spectrum by using future observations of 21 cm fluctuations and cosmic microwave background (CMB). For this purpose, we investigate projected constraints on the quantities characterizing primordial power spectrum: the spectral index n{sub s}, its running α{sub s} and even its higher order running β{sub s}. We show that future 21 cm observations in combinations with CMB would accurately measure above mentioned observables of primordial power spectrum. We also discuss its implications to some explicit inflationary models.

  20. Evidence for live 247Cm in the early solar system

    USGS Publications Warehouse

    Tatsumoto, M.; Shimamura, T.

    1980-01-01

    Variations of the 238U/235U ratio in the Allende meteorite, ranging from -35% to + 19%, are interpreted as evidence of live 247Cm in the early Solar System. The amounts of these and other r-products in the Solar System indicate values of (9,000??3,000) Myr for the age of the Galaxy and ??? 8 Myr for the time between the end of nucleosynthesis and the formation of meteoritic grains. Three possible explanations are presented for the different values of the latter time period which are indicated by the decay products of 247Cm, 26Al, 244Pu and 129I. ?? 1980 Nature Publishing Group.

  1. Cycle life testing of 8-cm mercury ion thruster cathodes

    NASA Technical Reports Server (NTRS)

    Wintucky, E. G.

    1976-01-01

    Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. The cycle life test results are presented along with results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

  2. Vertical distribution of soil removed by four species of burrowing rodents in disturbed and undisturbed soils

    SciTech Connect

    Reynolds, T.D.; Laundre, J.W.

    1988-04-01

    Burrow volumes were determined in disturbed and undisturbed soils for four species of rodents in southeastern Idaho. Comparisons were made between soil types for the average volume and the proportion of the total volume of soil excavated from 10-cm increments for each species, and the relative number of burrows and proportion of total soil removed from beneath the minimum thickness of soil covers over buried low-level radioactive wastes. Burrows of montane voles (Microtus montanus) and deer mice (Peromyscus maniculatus) rarely extended below 50 cm and neither volumes nor depths were influenced by soil disturbance. Townsend's ground squirrels (Spermophilus townsendii) had the deepest and most voluminous burrows that, along with Ord's kangaroo rat (Dipodomys ordii) burrows, were more prevalent beneath 50 cm in disturbed soils.

  3. Soil and Surface Runoff Phosphorus Relationships for Five Typical USA Midwest Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excessively high soil P can increase P loss with surface runoff. This study used indoor rainfall simulations to characterize soil and runoff P relationships for five Midwest soils (Argiudoll, Calciaquaoll, Hapludalf, and two Hapludolls). Topsoil (15-cm depth, 241–289 g clay kg–1 and pH 6.0–8.0) was ...

  4. Operation of a Five-Stage 40,000-CM(2)-Area Insulator Stack at 158 KV/CM

    SciTech Connect

    Anderson R.A.; Clark, Robert E.; Corcoran, P.A.; Douglas, John W.; Gilliland, T.L.; Horry, M.L.; Hughes, Thomas P.; Ives, H.C.; Long, F.W.; Martin, T.H.; McDaniel, D.H.; Milton, Osborne; Mostrom, Michael A.; Seamen, J.F.; Shoup, R.W.; Smith, I.D.; Smith, J.W.; Spielman, R.B.; Struve, K.W.; Stygar, W.A.; Vogtlin, George E.; Wagoner, T.C.; Yamamoto, Osamu

    1999-06-30

    We have demonstrated successful operation of a 3.35- m-diameter insulator stack at 158 kV/cm on five consecutive Z-accelerator shots. The stack consisted of five +45°-profile 5.715-cm-thick cross-linked-polystyrene (Rexolite- 1422) insulator rings, and four anodized- aluminum grading rings shaped to reduce the field at cathode triple junctions. The width of the voltage pulse at 89% of peak was 32 ns. We compare this result to a new empirical flashover relation developed from previous small-insulator experiments conducted with flat unanodized electrodes. The relation predicts a 50% flashover probability for a Rexolite insulator during an applied voltage pulse when Emaxe-0.27/d(teffC)1/10 = 224, where Emax is the peak mean electric field (kV/cm), d is the insulator thickness (cm), teff is the effective pulse width (ps), and C is the insulator circumference (cm). We find the Z stack can be operated at a stress at least 19% higher than predicted. This result, and previous experiments conducted by Vogtlin, suggest anodized electrodes with geometries that reduce the field at both anode and cathode triple junctions would improve the flashover strength of +45° insulators.

  5. The Complexity and Challenges of the ICD-9-CM to ICD-10-CM Transition in Emergency Departments

    PubMed Central

    Krive, Jacob; Patel, Mahatkumar; Gehm, Lisa; Mackey, Mark; Kulstad, Erik; Li, Jianrong ‘John’; Lussier, Yves A.; Boyd, Andrew D.

    2015-01-01

    Beginning October 2015, the Center for Medicare and Medicaid Services (CMS) will require medical providers to utilize the vastly expanded ICD-10-CM system. Despite wide availability of information and mapping tools for the next generation of the ICD classification system, some of the challenges associated with transition from ICD-9-CM to ICD-10-CM are not well understood. To quantify the challenges faced by emergency physicians, we analyzed a subset of a 2010 Illinois Medicaid database of emergency department ICD-9-CM codes, seeking to determine the accuracy of existing mapping tools in order to better prepare emergency physicians for the change to the expanded ICD-10-CM system. We found that 27% of 1,830 codes represented convoluted multidirectional mappings. We then analyzed the convoluted transitions and found 8% of total visit encounters (23% of the convoluted transitions) were clinically incorrect. The ambiguity and inaccuracy of these mappings may impact the work flow associated with the translation process and affect the potential mapping between ICD codes and CPT (Current Procedural Codes) codes, which determine physician reimbursement. PMID:25863652

  6. Topographical controls on soil moisture distribution and runoff response in a first order alpine catchment

    NASA Astrophysics Data System (ADS)

    Penna, Daniele; Gobbi, Alberto; Mantese, Nicola; Borga, Marco

    2010-05-01

    Hydrological processes driving runoff generation in mountain basins depend on a wide number of factors which are often strictly interconnected. Among them, topography is widely recognized as one of the dominant controls influencing soil moisture distribution in the root zone, depth to water table and location and extent of saturated areas possibly prone to runoff production. Morphological properties of catchments are responsible for the alternation between steep slopes and relatively flat areas which have the potentials to control the storage/release of water and hence the hydrological response of the whole watershed. This work aims to: i) identify the role of topography as the main factor controlling the spatial distribution of near-surface soil moisture; ii) evaluate the possible switch in soil moisture spatial organization between wet and relatively dry periods and the stability of patterns during triggering of surface/subsurface runoff; iii) assess the possible connection between the develop of an ephemeral river network and the groundwater variations, examining the influence of the catchment topographical properties on the hydrological response. Hydro-meteorological data were collected in a small subcatchment (Larch Creek Catchment, 0.033 km²) of Rio Vauz basin (1.9 km²), in the eastern Italian Alps. Precipitation, discharge, water table level over a net of 14 piezometric wells and volumetric soil moisture at 0-30 cm depth were monitored continuously during the late spring-early autumn months in 2007 and 2008. Soil water content at 0-6 and 0-20 cm depth was measured manually during 22 field surveys in summer 2007 over a 44-sampling point experimental plot (approximately 3000 m²). In summer 2008 the sampling grid was extended to 64 points (approximately 4500 m²) and 28 field surveys were carried out. The length of the ephemeral stream network developed during rainfall events was assessed by a net of 24 Overland Flow Detectors (OFDs), which are able to

  7. Influence of Acacia trees on soil nutrient levels in arid lands

    NASA Astrophysics Data System (ADS)

    De Boever, Maarten; Gabriels, Donald; Ouessar, Mohamed; Cornelis, Wim

    2014-05-01

    The potential of scattered trees as keystone structures in restoring degraded environments is gaining importance. Scattered trees have strong influence on their abiotic environment, mainly causing changes in microclimate, water budget and soil properties. They often function as 'nursing trees', facilitating the recruitment of other plants. Acacia raddiana is such a keystone species which persists on the edge of the Sahara desert. The study was conducted in a forest-steppe ecosystem in central Tunisia where several reforestation campaigns with Acacia took place. To indentify the impact of those trees on soil nutrients, changes in nutrient levels under scattered trees of three age stages were examined for the upper soil layer (0-10 cm) at five microsites with increasing distance from the trunk. In addition, changes in soil nutrient levels with depth underneath and outside the canopy were determined for the 0-30 cm soil layer. Higher concentrations of organic matter (OM) were found along the gradient from underneath to outside the canopy for large trees compared to medium and small trees, especially at microsites close to the trunk. Levels of soluble K, electrical conductivity (EC), available P, OM, total C and N decreased whereas pH and levels of soluble Mg increased with increasing distance from tree. Levels of soluble Ca and Na remained unchanged along the gradient. At the microsite closest to the trunk a significant decrease in levels of soluble K, EC, OM, available P, total C and N, while a significant increase in pH was found with increasing depth. The concentration of other nutrients remained unchanged or declined not differently underneath compared to outside the canopy with increasing depth. Differences in nutrient levels were largely driven by greater inputs of organic matter under trees. Hence, Acacia trees can affect the productivity and reproduction of understory species with the latter in term an important source of organic matter. This positive feedback

  8. Fast changes in seasonal forest communities due to soil moisture increase after damming.

    PubMed

    do Vale, Vagner Santiago; Schiavini, Ivan; Araújo, Glein Monteiro; Gusson, André Eduardo; Lopes, Sérgio de Faria; de Oliveira, Ana Paula; do Prado-Júnior, Jamir Afonso; Arantes, Carolina de Silvério; Dias-Neto, Olavo Custodio

    2013-12-01

    Local changes caused by dams can have drastic consequences for ecosystems, not only because they change the water regime but also the modification on lakeshore areas. Thus, this work aimed to determine the changes in soil moisture after damming, to understand the consequences of this modification on the arboreal community of dry forests, some of the most endangered systems on the planet. We studied these changes in soil moisture and the arboreal community in three dry forests in the Araguari River Basin, after two dams construction in 2005 and 2006, and the potential effects on these forests. For this, plots of 20 m x 10 m were distributed close to the impoundment margin and perpendicular to the dam margin in two deciduous dry forests and one semi-deciduous dry forest located in Southeastern Brazil, totaling 3.6 ha sampled. Besides, soil analysis were undertaken before and after impoundment at three different depths (0-10, 20-30 and 40-50 cm). A tree (minimum DBH of 4.77 cm) community inventory was made before (TO) and at two (T2) and four (T4) years after damming. Annual dynamic rates of all communities were calculated, and statistical tests were used to determine changes in soil moisture and tree communities. The analyses confirmed soil moisture increases in all forests, especially during the dry season and at sites closer to the reservoir; besides, an increase in basal area due to the fast growth of many trees was observed. The highest turnover occurred in the first two years after impoundment, mainly due to the higher tree mortality especially of those closer to the dam margin. All forests showed reductions in dynamic rates for subsequent years (T2-T4), indicating that these forests tended to stabilize after a strong initial impact. The modifications were more extensive in the deciduous forests, probably because the dry period resulted more rigorous in these forests when compared to semideciduous forest. The new shorelines created by damming increased soil

  9. Retrofit and acceptance test of 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.

    1981-01-01

    Six 30 cm mercury thrusters were modified to the J-series design and evaluated using standardized test procedures. The thruster performance meets the design objectives (lifetime objective requires verification), and documentation (drawings, etc.) for the design is completed and upgraded. The retrofit modifications are described and the test data for the modifications are presented and discussed.

  10. Search for Cm-248 in the early solar system

    NASA Technical Reports Server (NTRS)

    Lavielle, B.; Marti, K.; Pellas, P.; Perron, C.

    1992-01-01

    Possible evidence for the presence of Cm-248 in the early solar system was reported from fission gas studies (Rao and Gopalan, 1973) and recently from studies of very high nuclear track densities (not less than 5 x 10 exp 8/sq cm) in the merrillite of the H4 chondrite Forest Vale (F.V.) (Pellas et al., 1987). We report here an analysis of the isotopic abundances of xenon in F.V. phosphates and results of track studies in phosphate/pyroxene contacts. The fission xenon isotopic signature clearly identifies Pu-244 as the extinct progenitor. We calculate an upper limit Cm-248/Pu-244 to be less than 0.0015 at the beginning of Xe retention in F.V. phosphates. This corresponds to an upper limit of the ratio Cm-248/U-235 of not greater than 5 x 10 exp -5 further constraining the evidence for any late addition of freshly synthesized actinide elements just prior to solar system formation. The fission track density observed after annealing the phosphates at 290C (1 hr, which essentially erases spallation recoil tracks) is also in agreement with the Pu-244 abundance inferred from fission Xe. The spallation recoil tracks produced during the 76 Ma cosmic-ray exposure account for the very high track density in merrillites.

  11. Adaptation of California Measure of Mental Motivation-CM3

    ERIC Educational Resources Information Center

    Özdemir, Hasan Fehmi; Demirtasli, Nükhet Çikrikçi

    2015-01-01

    Education without doubt, plays a vital role for individuals to gain the essential personal traits of the 21st century, also known as "knowledge age". One of the most important skills among these fundamental qualities which the individuals should be equipped with is critical thinking. California Measure of Mental Motivation-CM3 was…

  12. Cosmological constraints from 21cm surveys after reionization

    SciTech Connect

    Visbal, Eli; Loeb, Abraham; Wyithe, Stuart E-mail: aloeb@cfa.harvard.edu

    2009-10-01

    21cm emission from residual neutral hydrogen after the epoch of reionization can be used to trace the cosmological power spectrum of density fluctuations. Using a Fisher matrix formulation, we provide a detailed forecast of the constraints on cosmological parameters that are achievable with this probe. We consider two designs: a scaled-up version of the MWA observatory as well as a Fast Fourier Transform Telescope. We find that 21cm observations dedicated to post-reionization redshifts may yield significantly better constraints than next generation Cosmic Microwave Background (CMB) experiments. We find the constraints on Ω{sub Λ}, Ω{sub m}h{sup 2}, and Ω{sub ν}h{sup 2} to be the strongest, each improved by at least an order of magnitude over the Planck CMB satellite alone for both designs. Our results do not depend as strongly on uncertainties in the astrophysics associated with the ionization of hydrogen as similar 21cm surveys during the epoch of reionization. However, we find that modulation of the 21cm power spectrum from the ionizing background could potentially degrade constraints on the spectral index of the primordial power spectrum and its running by more than an order of magnitude. Our results also depend strongly on the maximum wavenumber of the power spectrum which can be used due to non-linearities.

  13. The 21 cm signature of a cosmic string loop

    SciTech Connect

    Pagano, Michael; Brandenberger, Robert E-mail: rhb@physics.mcgill.ca

    2012-05-01

    Cosmic string loops lead to nonlinear baryon overdensities at early times, even before the time which in the standard LCDM model corresponds to the time of reionization. These overdense structures lead to signals in 21 cm redshift surveys at large redshifts. In this paper, we calculate the amplitude and shape of the string loop-induced 21 cm brightness temperature. We find that a string loop leads to a roughly elliptical region in redshift space with extra 21 cm emission. The excess brightness temperature for strings with a tension close to the current upper bound can be as high as 1deg K for string loops generated at early cosmological times (times comparable to the time of equal matter and radiation) and observed at a redshift of z+1 = 30. The angular extent of these predicted 'bright spots' is x{sup '}. These signals should be detectable in upcoming high redshift 21 cm surveys. We also discuss the application of our results to global monopoles and primordial black holes.

  14. Calorimetric determination of kQ factors for NE 2561 and NE 2571 ionization chambers in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV photons

    NASA Astrophysics Data System (ADS)

    Krauss, Achim; Kapsch, Ralf-Peter

    2007-10-01

    The relative uncertainty of the ionometric determination of the absorbed dose to water, Dw, in the reference dosimetry of high-energy photon beams is in the order of 1.5% and is dominated by the uncertainty of the calculated chamber- and energy-dependent correction factors kQ. In the present investigation, kQ values were determined experimentally in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV bremsstrahlung by means of a water calorimeter operated at 4 °C. Ionization chambers of the types NE 2561 and NE 2571 were calibrated directly in the water phantom of the calorimeter. The measurements were carried out at the linear accelerator of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factor of a single ionization chamber can be measured with a standard uncertainty of less than 0.3%. No significant variations of kQ were found for the different lateral sizes of the radiation fields used in this investigation.

  15. Electronic and magnetic properties of Am and Cm

    SciTech Connect

    Edelstein, N.

    1985-02-01

    A review of the present status of the analyses of the optical spectra of Am and Cm in various oxidation states is given. From these analyses, the magnetic properties of the ground states of these ions can be determined. These predicted values are compared with the various magnetic measurements available.

  16. Influence of calcium content on the structural and magnetic properties of Sr0.70-xCaxLa0.30Fe11.75Zn0.25O19 hexagonal ferrites

    NASA Astrophysics Data System (ADS)

    Yang, Yujie; Wang, Fanhou; Shao, Juxiang; Liu, Xiansong; Feng, Shuangjiu; Yang, Junsheng

    2016-03-01

    Hexagonal ferrite Sr0.70-xCaxLa0.30Fe11.75Zn0.25O19 (0≤x≤0.70) magnetic powder and magnets were prepared by the ceramic process. The phase characterization of the calcined powders was investigated by X-ray diffraction. There is a single magnetoplumbite phase in the magnetic powders with x from 0 to 0.60, and for the magnetic powders with x of 0.70, the α-Fe2O3 phase is observed. The morphology of the sintered magnets was examined by a field emission scanning electron microscopy. The magnets have formed the hexagonal structures and the particles are distributed evenly. Magnetic properties of the calcined powders and sintered magnets were measured by a vibrating sample magnetometer and a magnetic properties test instrument, respectively. The saturation magnetization, remanent magnetization and coercivity of the magnetic powders increase with the increase of x from 0 to 0.2, and then begin to decrease when x>0.2. The remanence, intrinsic coercivity, magnetic induction coercivity and maximum energy product of the sintered magnets first increase with x from 0 to 0.20, and then, start to decrease when x continues to increase. The magnetic properties of the sintered magnet at x=0.20 reach the maximum values.

  17. Observation of bi-relaxor characteristic in multiferroic 0.70Bi0.90Ca0.10FeO3-0.30PbTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Tirupathi, Patri; Chandra, Amreesh

    2013-09-01

    The coexistence of bi-relaxor property, i.e. ferroelectric relaxor as well as spin glass type behaviour, is observed in disordered multiferroic ceramic 0.70Bi0.90Ca0.10FeO3-0.30PbTiO3. The real parts of dielectric permittivity and magnetic susceptibility show pronounced frequency dispersion near the corresponding phase transition temperatures, namely, Tc ≈ 550 K and TN ≈ 110 K, respectively. The relaxor behaviour observed in temperature-dependent dielectric constant measurement is confirmed by fitting of the Vogel-Fulcher equation. Similarly, magnetic spin glass behaviour is proven by power law fitting. The origin of such bi-relaxor in the present system can be attributed to the disorder and frustration among the uncompensated spins of the Fe-ion. This has been confirmed by analysing the x-ray photoelectron (XPS) spectrum of the sample under investigation. Using FESEM micrographs, the coexistence of nano-sized and bulk grains is shown. The importance of such coexistence is discussed and also presented in the paper.

  18. Magnetic and electrical transport properties of La0.65Ca0.30Pb0.05Mn0.90Cu0.10O3 compounds: Thermal hysteresis

    NASA Astrophysics Data System (ADS)

    Irmak, A. E.; Taşarkuyu, E.; Coşkun, A.; Acet, M.; Samancıoğlu, Y.; Aktürk, S.

    2015-08-01

    Structural, electrical, and magnetic properties of La0.65(Ca0.30Pb0.05)Mn0.90Cu0.10O3 compound were investigated. The compound, prepared by the sol-gel route, was pressed into pellets and one of them was sintered at 900 °C and the other at 1000 °C for 24 h. The aim of the study was to explore structural, electrical and magnetic properties of the compound. Temperature dependent X-ray powder diffraction studies on the sample sintered at 900 °C reveal an orthorhombic-Pbnm perovskite structure through the temperature range between 320 K and 86 K. Scanning electron microcopy and energy dispersive spectroscopy analyses showed grainy, homogeneous and stoichiometric structure. Magnetization and resistivity measurements reveal that the Curie temperatures, TC, and insulator-metal transition temperatures, TIM, coincide, but the samples sintered at 900 °C also exhibit thermal hysteresis both in magnetization and resistivity upon cooling and warming.

  19. Influence of heat treatment temperatures on structural and magnetic properties of Sr0.50Ca0.20La0.30Fe11.15Co0.25O19 hexagonal ferrites

    NASA Astrophysics Data System (ADS)

    Yang, Yujie; Liu, Xiansong; Jin, Dali

    2014-09-01

    M-type ferrite Sr0.50Ca0.20La0.30Fe11.15Co0.25O19 magnetic powders and magnets were prepared by a ceramic process. The phase identification of magnetic powders was performed by X-ray diffraction. At calcination temperatures ranging from 1170 to 1270 °C, the phase compositions of the magnetic powders consist of M-type hexaferrites together with small amount of impurity phases such as α-Fe2O3, LaFeO3 and CoFe2O4. At calcination temperatures above 1270 °C, single-phase M-type hexaferrites can be obtained. The microstructures of the magnets were investigated by field emission scanning electron microscopy. The particles appear in hexagonal plate-like shape and the particles are distributed homogeneously. The radial shrinkage of the magnets increases with the increase of calcination or sintering temperature. The magnetic properties of the magnets and magnetic powders were measured by a permanent magnetic measure equipment and a vibrating sample magnetometer, respectively. For high remanence, intrinsic coercivity, magnetic induction coercivity and maximum energy product, the optimized calcination and sintering temperatures are 1250 °C and 1190 °C, respectively.

  20. Effects of Zr-Substitution on Microwave Dielectric Properties of Na0.5Nd0.2Sm0.3Ti1-x Zr x O3 Ceramics (x = 0.00 ˜ 0.30)

    NASA Astrophysics Data System (ADS)

    Fang, Zixuan; Tang, Bin; Si, Feng; Gong, Yuting; Zhang, Shuren

    2016-07-01

    In this paper, the compound Na0.5Nd0.2Sm0.3Ti1-x Zr x O3 (NNSTZx, x = 0.00, 0.01, 0.02, 0.05, 0.09, 0.14, 0.20, 0.30) ceramics were prepared by the conventional solid-state route. The main phase of all NNSTZx samples were indexed as an orthorhombic perovskite structure. The permittivity (ɛ r) and quality factor (Q × f) were improved because of improvement of relative density and homogeneous microstructure with minor Zr substitution (x ≤ 0.02). When x ≤ 0.14, the temperature coefficient of the resonant frequency (τ f) could be effectively tuned to a relatively low value of 110.3 ppm/°C due to a continuous decrease of tolerance factors. A remarkable decrease of τf from 110.3 ppm/°C to -2.38 ppm/°C was obtained since a certain amount of Nd2Ti2O7 phase was observed with x ≥ 0.20. Typically, the NNSTZx (x = 0.20) ceramic sintered in air at 1450°C for 2 h exhibited good microwave dielectric properties of ɛ r = 75.4, Q × f=6813 GHz, and τ f = 67.8 ppm/°C.

  1. Disorder-driven phase transition in La{sub 0.37}D{sub 0.30}Ca{sub 0.33}MnO{sub 3} (D = Bi, Sm) manganites

    SciTech Connect

    Ade, Ramesh; Singh, R.

    2015-08-15

    In the present work we report the structural, electron spin resonance (ESR) and magnetic properties of La{sub 0.37}D{sub 0.30}Ca{sub 0.33}MnO{sub 3} (D = Bi, Sm) manganites synthesized by sol-gel method. The critical behavior at the critical point, where the system undergoes phase transition from paramagnetic (PM) to ferromagnetic (FM) state, is investigated by using modified-Arrott plots, Kouvel-Fisher method and critical isotherm analysis. Both the samples show second-order phase transition near the critical point. The decrease in magnetization (M), Curie temperature (T{sub C}), evolution of spin or cluster glass behavior and the nature of second-order phase transition compared to the first-order transition reported in the literature for La{sub 0.67}Ca{sub 0.33}MnO{sub 3} are ascribed to disorder caused by the size mismatch of the A-site cations with Bi and Sm doping at La-site.

  2. Maribo—A new CM fall from Denmark

    NASA Astrophysics Data System (ADS)

    Haack, Henning; Grau, Thomas; Bischoff, Addi; Horstmann, Marian; Wasson, John; Sørensen, Anton; Laubenstein, Matthias; Ott, Ulrich; Palme, Herbert; Gellissen, Marko; Greenwood, Richard C.; Pearson, Victoria K.; Franchi, Ian A.; Gabelica, Zelimir; Schmitt-Kopplin, Philippe

    2012-01-01

    Maribo is a new Danish CM chondrite, which fell on January 17, 2009, at 19:08:28 CET. The fall was observed by many eye witnesses and recorded by a surveillance camera, an all sky camera, a few seismic stations, and by meteor radar observatories in Germany. A single fragment of Maribo with a dry weight of 25.8 g was found on March 4, 2009. The coarse-grained components in Maribo include chondrules, fine-grained olivine aggregates, large isolated lithic clasts, metals, and mineral fragments (often olivine), and rare Ca,Al-rich inclusions. The components are typically rimmed by fine-grained dust mantles. The matrix includes abundant dust rimmed fragments of tochilinite with a layered, fishbone-like texture, tochilinite-cronstedtite intergrowths, sulfides, metals, and carbonates often intergrown with tochilinite. The oxygen isotopic composition: (δ17O = -1.27‰; δ18O = 4.96‰; Δ17O = -3.85‰) plots at the edge of the CM field, close to the CCAM line. The very low Δ17O and the presence of unaltered components suggest that Maribo is among the least altered CM chondrites. The bulk chemistry of Maribo is typical of CM chondrites. Trapped noble gases are similar in abundance and isotopic composition to other CM chondrites, stepwise heating data indicating the presence of gas components hosted by presolar diamond and silicon carbide. The organics in Maribo include components also seen in Murchison as well as nitrogen-rich components unique to Maribo.

  3. Soil Evaporation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil evaporation can significantly influence energy flux partitioning of partially vegetated surfaces, ultimately affecting plant transpiration. While important, quantification of soil evaporation, separately from canopy transpiration, is challenging. Techniques for measuring soil evaporation exis...

  4. Alpine grassland soil organic carbon stock and its uncertainty in the three rivers source region of the Tibetan Plateau.

    PubMed

    Chang, Xiaofeng; Wang, Shiping; Cui, Shujuan; Zhu, Xiaoxue; Luo, Caiyun; Zhang, Zhenhua; Wilkes, Andreas

    2014-01-01

    Alpine grassland of the Tibetan Plateau is an important component of global soil organic carbon (SOC) stocks, but insufficient field observations and large spatial heterogeneity leads to great uncertainty in their estimation. In the Three Rivers Source Region (TRSR), alpine grasslands account for more than 75% of the total area. However, the regional carbon (C) stock estimate and their uncertainty have seldom been tested. Here we quantified the regional SOC stock and its uncertainty using 298 soil profiles surveyed from 35 sites across the TRSR during 2006-2008. We showed that the upper soil (0-30 cm depth) in alpine grasslands of the TRSR stores 2.03 Pg C, with a 95% confidence interval ranging from 1.25 to 2.81 Pg C. Alpine meadow soils comprised 73% (i.e. 1.48 Pg C) of the regional SOC estimate, but had the greatest uncertainty at 51%. The statistical power to detect a deviation of 10% uncertainty in grassland C stock was less than 0.50. The required sample size to detect this deviation at a power of 90% was about 6-7 times more than the number of sample sites surveyed. Comparison of our observed SOC density with the corresponding values from the dataset of Yang et al. indicates that these two datasets are comparable. The combined dataset did not reduce the uncertainty in the estimate of the regional grassland soil C stock. This result could be mainly explained by the underrepresentation of sampling sites in large areas with poor accessibility. Further research to improve the regional SOC stock estimate should optimize sampling strategy by considering the number of samples and their spatial distribution. PMID:24819054

  5. Soil carbon stock and soil characteristics at Tasik Chini Forest Reserve, Pahang, Malaysia

    NASA Astrophysics Data System (ADS)

    Nur Aqlili Riana, R.; Sahibin A., R.

    2015-09-01

    This study was carried out to determine soil carbon stock and soil characteristic at Tasik Chini Forest Reserve (TCFR), Pahang. A total of 10 (20 m x 25 m) permanent sampling plot was selected randomly within the area of TCFR. Soil samples were taken from all subplots using dutch auger based on soil depth of 0-20cm, 20-40cm, 40-60cm. Soil parameters determined were size distribution, soil water content, bulk density, organic matter, organic carbon content, pH and electrical conductivity. All parameters were determined following their respective standard methods. Results obtained showed that the soil in TCFR was dominated by clay texture (40%), followed by sandy clay loam (30%), loam (20%). Silty clay, clay loam and sandy loam constitutes about 10% of the soil texture. Range of mean percentage of organic matter and bulk density are from 2.42±0.06% to 11.64±0.39% and 1.01 to 1.04 (gcm-ł), respectively. Soil pH are relatively very acidic and mean of electrical conductivity is low. Soil carbon content ranged from 0.83±0.03 to 1.87±0.41%. All soil parameter showed a decreasing trend with depth except electrical conductivity. ANOVA test of mean percentage of organic matter, soil water content, soil pH and electrical conductivity showed a significant difference between plot (p<0.05). However there are no significant difference of mean bulk density between plots (p>0.05). There are no significant difference in mean percentage of soil water content, organic matter and bulk density between three different depth (p>0.05). There were a significant difference on percentage of soil carbon organic between plots and depth. The mean of soil organic carbon stock in soil to a depth of 60 cm calculated was 35.50 t/ha.

  6. Biochemical activities in soil overlying Paraho processed oil shale

    SciTech Connect

    Sorensen, D.L.

    1982-01-01

    Microbial activity development in soil materials placed over processed oil shale is vital to the plant litter decomposition, cycling of nutrients, and soil organic matter accumulation and maintenance. Samples collected in the summers of 1979, 1980, and 1981 from revegetated soil 30-, 61-, and 91-cm deep overlying spent oil shale in the Piceance Basin of northwestern Colorado were assayed for dehydrogenease activity with glucose and without glucose, for phosphatase activity, and for acetylene reduction activity. Initial ammonium and nitrite nitrogen oxidation rates and potential denitrification rates were determined in 1981. Zymogenous dehydrogenase activity, phosphatase activity, nitrogenase activity, potential denitrification rates, and direct microscopic counts were lower in surface soil 30 cm deep, and were frequently lower in surface soil 61 cm deep over processed shale than in a surface-disturbed control area soil. Apparently, microbial activities are stressed in these more shallow replaced soils. Soil 61 cm deep over a coarse-rock capillary barrier separating the soil from the spent shale, frequently had improved biochemical activity. Initial ammonium and nitrite nitrogen oxidation rates were lower in all replaced soils than in the disturbed control soil. Soil core samples taken in 1981 were assayed for dehydrogenase and phosphatase activities, viable bacteria, and viable fungal propagules. In general, microbial activity decreased quickly below the surface. At depths greater than 45 cm, microbial activities were similar in buried spent shale and surface-disturbed control soil.

  7. The Paris meteorite, the least altered CM chondrite so far

    NASA Astrophysics Data System (ADS)

    Hewins, Roger H.; Bourot-Denise, Michèle; Zanda, Brigitte; Leroux, Hugues; Barrat, Jean-Alix; Humayun, Munir; Göpel, Christa; Greenwood, Richard C.; Franchi, Ian A.; Pont, Sylvain; Lorand, Jean-Pierre; Cournède, Cécile; Gattacceca, Jérôme; Rochette, Pierre; Kuga, Maïa; Marrocchi, Yves; Marty, Bernard

    2014-01-01

    The Paris chondrite provides an excellent opportunity to study CM chondrules and refractory inclusions in a more pristine state than currently possible from other CMs, and to investigate the earliest stages of aqueous alteration captured within a single CM bulk composition. It was found in the effects of a former colonial mining engineer and may have been an observed fall. The texture, mineralogy, petrography, magnetic properties and chemical and isotopic compositions are consistent with classification as a CM2 chondrite. There are ∼45 vol.% high-temperature components mainly Type I chondrules (with olivine mostly Fa0-2, mean Fa0.9) with granular textures because of low mesostasis abundances. Type II chondrules contain olivine Fa7 to Fa76. These are dominantly of Type IIA, but there are IIAB and IIB chondrules, II(A)B chondrules with minor highly ferroan olivine, and IIA(C) with augite as the only pyroxene. The refractory inclusions in Paris are amoeboid olivine aggregates (AOAs) and fine-grained spinel-rich Ca-Al-rich inclusions (CAIs). The CAI phases formed in the sequence hibonite, perovskite, grossite, spinel, gehlenite, anorthite, diopside/fassaite and forsterite. The most refractory phases are embedded in spinel, which also occurs as massive nodules. Refractory metal nuggets are found in many CAI and refractory platinum group element abundances (PGE) decrease following the observed condensation sequences of their host phases. Mn-Cr isotope measurements of mineral separates from Paris define a regression line with a slope of 53Mn/55Mn = (5.76 ± 0.76) × 106. If we interpret Cr isotopic systematics as dating Paris components, particularly the chondrules, the age is 4566.44 ± 0.66 Myr, which is close to the age of CAI and puts new constraints on the early evolution of the solar system. Eleven individual Paris samples define an O isotope mixing line that passes through CM2 and CO3 falls and indicates that Paris is a very fresh sample, with variation explained

  8. Soil adherence to human skin

    SciTech Connect

    Driver, J.H.; Konz, J.J.; Whitmyre, G.K. )

    1989-12-01

    Dermal exposure to soils contaminated with toxic chemicals represents a potential public health hazard. These soils, contaminated with chemicals such as PCBs and dioxins, may be found at various locations throughout the US. Furthermore, dermal contact with pesticide-containing particles and contaminated soil particles is of importance for exposures to agricultural workers who reenter fields after pesticide application. With respect to dermal exposure to pesticide-contaminated particulate matter, several occurrences of human toxicity to ethyl parathion in citrus groves have been reported. These exposures resulted from dermal contact with high concentrations of the toxic transformation product paraoxon in soil dust contaminated as a result of application of pesticide to the overhead foliage of trees. To assess dermal exposure to chemically-contaminated soil at sites of concern, dermal adherence of soil must be determined prior to the assessment of dermal absorption. The purpose of the experiment reported herein was to determine the amount of soil (mg/cm{sup 2}) that adheres to adult hands under various soil conditions. These conditions include the type of soil, the organic content of the soil, and the particle size of the soil.

  9. POLYSHIFT Communications Software for the Connection Machine System CM-200

    DOE PAGESBeta

    George, William; Brickner, Ralph G.; Johnsson, S. Lennart

    1994-01-01

    We describe the use and implementation of a polyshift function PSHIFT for circular shifts and end-offs shifts. Polyshift is useful in many scientific codes using regular grids, such as finite difference codes in several dimensions, and multigrid codes, molecular dynamics computations, and in lattice gauge physics computations, such as quantum chromodynamics (QCD) calculations. Our implementation of the PSHIFT function on the Connection Machine systems CM-2 and CM-200 offers a speedup of up to a factor of 3–4 compared with CSHIFT when the local data motion within a node is small. The PSHIFT routine is included in the Connection Machine Scientificmore » Software Library (CMSSL).« less

  10. Precision measurement of cosmic magnification from 21 cm emitting galaxies

    SciTech Connect

    Zhang, Pengjie; Pen, Ue-Li; /Canadian Inst. Theor. Astrophys.

    2005-04-01

    We show how precision lensing measurements can be obtained through the lensing magnification effect in high redshift 21cm emission from galaxies. Normally, cosmic magnification measurements have been seriously complicated by galaxy clustering. With precise redshifts obtained from 21cm emission line wavelength, one can correlate galaxies at different source planes, or exclude close pairs to eliminate such contaminations. We provide forecasts for future surveys, specifically the SKA and CLAR. SKA can achieve percent precision on the dark matter power spectrum and the galaxy dark matter cross correlation power spectrum, while CLAR can measure an accurate cross correlation power spectrum. The neutral hydrogen fraction was most likely significantly higher at high redshifts, which improves the number of observed galaxies significantly, such that also CLAR can measure the dark matter lensing power spectrum. SKA can also allow precise measurement of lensing bispectrum.

  11. Intensity Mapping During Reionization: 21 cm and Cross-correlations

    NASA Astrophysics Data System (ADS)

    Aguirre, James E.; HERA Collaboration

    2016-01-01

    The first generation of 21 cm epoch of reionization (EoR) experiments are now reaching the sensitivities necessary for a detection of the power spectrum of plausible reionization models, and with the advent of next-generation capabilities (e.g. the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometer Array Phase I Low) will move beyond the power spectrum to imaging of the EoR intergalactic medium. Such datasets provide context to galaxy evolution studies for the earliest galaxies on scales of tens of Mpc, but at present wide, deep galaxy surveys are lacking, and attaining the depth to survey the bulk of galaxies responsible for reionization will be challenging even for JWST. Thus we seek useful cross-correlations with other more direct tracers of the galaxy population. I review near-term prospects for cross-correlation studies with 21 cm and CO and CII emission, as well as future far-infrared misions suchas CALISTO.

  12. Performance of the NASA 30 cm Ion Thruster

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Haag, Thomas W.; Hovan, Scot A.

    1993-01-01

    A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest, and is being proposed for use on the USAF/TRW Space Surveillance, Tracking and Autonomous Repositioning (SSTAR) platform to validate ion propulsion. The thruster incorporates innovations in design, materials, and fabrication techniques compared to those employed in conventional ion thrusters. Specific development efforts include thruster design optimizations, component life testing and validation, vibration testing, and performance characterizations. Under this test program, the ion thruster will be brought to engineering model development status. This paper discusses the performance and power throttling test data for the NASA 30 cm diameter xenon ion thruster over an input power envelope of 0.7 to 4.9 kW, and corresponding thruster lifetime expectations.

  13. Lensing of 21-cm fluctuations by primordial gravitational waves.

    PubMed

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed. PMID:23003237

  14. Lensing of 21-cm Fluctuations by Primordial Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-01

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r˜10-9—far smaller than those currently accessible—to be probed.

  15. Viscoelastic hydrodynamic interactions and anomalous CM diffusion in polymer melts

    NASA Astrophysics Data System (ADS)

    Meyer, Hendrik; Farago, Jean; Semenov, A. N.

    2014-03-01

    We have recently discovered that anomalous center-of-mass (CM) diffusion occurring on intermediate time scales in polymer melts can be explained by the interplay of viscoelastic and hydrodynamic interactions (VHI). The theory has been solved for unentangled melts in 3D and 2D and excellent agreement between theory and simulation is found. The physical mechanism considers that hydrodynamic interactions are time dependent because of increasing viscosity before the terminal relaxation time; it is generally active in melts of any topology. Surprisingly, the effects are relevant for both, momentum-conserving and Langevin dynamics and this presentation will focus on the differences: The commonly employed Langevin thermostat significantly changes the CM motion on short and intermediate time scales, but approaching the Rouse time, the melt behavior is close to momentum-conserving simulations. On the other hand, if momentum-conserving simulations are run in too small a simulation box, the result looks as if a Langevin thermostat was used.

  16. Development of a 60 cm Magnetic Suspension System

    NASA Astrophysics Data System (ADS)

    Sawada, Hideo; Kunimasu, Tetsuya

    A 60cm Magnetic Suspension Balance System (MSBS), which has been developed in the National Aerospace Laboratory of Japan (NAL), is described in detail. Magnetic field in the MSBS is evaluated analytically and is compared with measured one. Available magnet kinds for the MSBS are selected analytically. The optimum ratio of diameter to length of cylindrical magnet for the MSBS is also evaluated. A model position sensing and the control systems are described with calibration test results. A model holding system is also shown, which is necessary for worker’s safety at suspending a large and massive model. The control system is presented and the measured model position during suspension is examined. The balance accuracy is examined and its error of drag force can be improved by restricting the calibration test to an expected drag range. Flow of the 60cm low-speed wind tunnel equipped with the MSBS is examined to be available for wind tunnel tests.

  17. 21 cm cosmology in the 21st century.

    PubMed

    Pritchard, Jonathan R; Loeb, Abraham

    2012-08-01

    Imaging the Universe during the first hundreds of millions of years remains one of the exciting challenges facing modern cosmology. Observations of the redshifted 21 cm line of atomic hydrogen offer the potential of opening a new window into this epoch. This will transform our understanding of the formation of the first stars and galaxies and of the thermal history of the Universe. A new generation of radio telescopes is being constructed for this purpose with the first results starting to trickle in. In this review, we detail the physics that governs the 21 cm signal and describe what might be learnt from upcoming observations. We also generalize our discussion to intensity mapping of other atomic and molecular lines. PMID:22828208

  18. Evidence of hydrocarbon pollution in soil exploiting satellite optical and radar images

    NASA Astrophysics Data System (ADS)

    Monsivais-Huertero, A.; Galvan-Pineda, J.; Espinosa-Hernandez, A.; Jimenez-Escalona, J. C.; Ramos-Rodriguez, J. M.

    2013-05-01

    includes field measurements collecting soil samples at depths of 0-30 cm and 30-60 cm, the implementation of an algorithm to exploit Landsat 5 and 7 images to identify polluted zones, and the implementation of an algorithm using Envisat ASAR and an incoherent scattering model to delineate the polluted soil. The laboratory analysis of the soil samples showed that in all cases the most contaminated region of the soil is the deeper layer (30-60 cm). The processing of the optical images identifies contaminated regions mainly for bare soils and short vegetation. For highly vegetated regions, the optical images do not detect the polluted soils because the wavelength of observation cannot penetrate vegetation. The radar algorithm indicates that the most contaminated zones showed the lowest backscattering coefficient in comparison to clean zones. Unlike optical images, the Envisat images allowed the identification of polluted zones even under high vegetation conditions.

  19. OH 18 cm Transition as a Thermometer for Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Ebisawa, Yuji; Inokuma, Hiroshi; Sakai, Nami; Menten, Karl M.; Maezawa, Hiroyuki; Yamamoto, Satoshi

    2015-12-01

    We have observed the four hyperfine components of the 18 cm OH transition toward the translucent cloud eastward of Heiles Cloud 2 (HCL2E), the cold dark cloud L134N, and the photodissociation region of the ρ-Ophiuchi molecular cloud with the Effelsberg 100 m telescope. We have found intensity anomalies among the hyperfine components in all three regions. In particular, an absorption feature of the 1612 MHz satellite line against the cosmic microwave background has been detected toward HCL2E and two positions of the ρ-Ophiuchi molecular cloud. On the basis of statistical equilibrium calculations, we find that the hyperfine anomalies originate from the non-LTE population of the hyperfine levels, and can be used to determine the kinetic temperature of the gas over a wide range of H2 densities (102-107 cm-3). Toward the center of HCL2E, the gas kinetic temperature is determined to be 53 ± 1 K, and it increases toward the cloud peripheries (˜60 K). The ortho-to-para ratio of H2 is determined to be 3.5 ± 0.9 from the averaged spectrum for the eight positions. In L134N, a similar increase of the temperature is also seen toward the periphery. In the ρ-Ophiuchi molecular cloud, the gas kinetic temperature decreases as a function of the distance from the exciting star HD 147889. These results demonstrate a new aspect of the OH 18 cm line that can be used as a good thermometer of molecular cloud envelopes. The OH 18 cm line can be used to trace a new class of warm molecular gas surrounding a molecular cloud, which is not well traced by the emission of CO and its isotopologues.

  20. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide: (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  1. Identifying Ionized Regions in Noisy Redshifted 21 cm Data Sets

    NASA Astrophysics Data System (ADS)

    Malloy, Matthew; Lidz, Adam

    2013-04-01

    One of the most promising approaches for studying reionization is to use the redshifted 21 cm line. Early generations of redshifted 21 cm surveys will not, however, have the sensitivity to make detailed maps of the reionization process, and will instead focus on statistical measurements. Here, we show that it may nonetheless be possible to directly identify ionized regions in upcoming data sets by applying suitable filters to the noisy data. The locations of prominent minima in the filtered data correspond well with the positions of ionized regions. In particular, we corrupt semi-numeric simulations of the redshifted 21 cm signal during reionization with thermal noise at the level expected for a 500 antenna tile version of the Murchison Widefield Array (MWA), and mimic the degrading effects of foreground cleaning. Using a matched filter technique, we find that the MWA should be able to directly identify ionized regions despite the large thermal noise. In a plausible fiducial model in which ~20% of the volume of the universe is neutral at z ~ 7, we find that a 500-tile MWA may directly identify as many as ~150 ionized regions in a 6 MHz portion of its survey volume and roughly determine the size of each of these regions. This may, in turn, allow interesting multi-wavelength follow-up observations, comparing galaxy properties inside and outside of ionized regions. We discuss how the optimal configuration of radio antenna tiles for detecting ionized regions with a matched filter technique differs from the optimal design for measuring power spectra. These considerations have potentially important implications for the design of future redshifted 21 cm surveys.

  2. Power distribution for an Am/Cm bushing melter

    SciTech Connect

    Gong, C.; Hardy, B.J.

    1996-12-31

    Decades of nuclear material production at the Savannah River Site (SRS) has resulted in the generation of large quantities of the isotopes Am{sup 243} and Cm{sup 244}. Currently, the Am and Cm isotopes are stored as a nitric acid solution in a tank. The Am and Cm isotopes have great commercial value but must be transferred to ORNL for processing. The nitric acid solution contains other isotopes and is intensely radioactive, which makes storage a problem and precludes shipment in the liquid form. In order to stabilize the material for onsite storage and to permit transport the material from SRS to ORNL, it has been proposed that the Am and Cm be separated from other isotopes in the solution and vitrified. Vitrification will be effected by depositing a liquid feed stream containing the isotopes in solution, together with a stream of glass frit, onto the top of a molten glass pool in a melter. The glass is non-conducting and the melter is a Platinum/Rhodium alloy vessel which is heated by passing an electric current through it. Because most of the power is required to evaporate the liquid feed at the top of the glass pool, power demands differ for the upper and lower parts of the melter. In addition, the melter is batch fed so that the local power requirements vary with time. In order to design a unique split power supply, which ensures adequate local power delivery, an analysis of the melter power distribution was performed with the ABAQUS finite element code. ABAQUS was used to calculate the electric potential and current density distributions in the melter for a variety of current and potential boundary conditions. The results of the calculation were compared with test data and will be used to compute power densities for input to a computational fluid dynamics model for the melter.

  3. The 21 cm signature of cosmic string wakes

    SciTech Connect

    Brandenberger, Robert H.; Danos, Rebecca J.; Hernández, Oscar F.; Holder, Gilbert P. E-mail: rjdanos@physics.mcgill.ca E-mail: holder@physics.mcgill.ca

    2010-12-01

    We discuss the signature of a cosmic string wake in 21cm redshift surveys. Since 21cm surveys probe higher redshifts than optical large-scale structure surveys, the signatures of cosmic strings are more manifest in 21cm maps than they are in optical galaxy surveys. We find that, provided the tension of the cosmic string exceeds a critical value (which depends on both the redshift when the string wake is created and the redshift of observation), a cosmic string wake will generate an emission signal with a brightness temperature which approaches a limiting value which at a redshift of z+1 = 30 is close to 400 mK in the limit of large string tension. The signal will have a specific signature in position space: the excess 21cm radiation will be confined to a wedge-shaped region whose tip corresponds to the position of the string, whose planar dimensions are set by the planar dimensions of the string wake, and whose thickness (in redshift direction) depends on the string tension. For wakes created at z{sub i}+1 = 10{sup 3}, then at a redshift of z+1 = 30 the critical value of the string tension μ is Gμ = 6 × 10{sup −7}, and it decreases linearly with redshift (for wakes created at the time of equal matter and radiation, the critical value is a factor of two lower at the same redshift). For smaller tensions, cosmic strings lead to an observable absorption signal with the same wedge geometry.

  4. Mineralogy of an unusual CM clast in the Kaidun meteorite

    NASA Technical Reports Server (NTRS)

    Zolensky, M. E.; Ivanov, A. V.; Yang, S. V.; Barrett, R. A.; Browning, L.

    1994-01-01

    Kaidun is breccia of disparate enstatite and carbonaceous chondrite clasts, and continues to provide real surprises. Many Daidun clasts have been intensely altered by an aqueous fluid, as evidenced by the widespread occurrence of ferromagnesian phyllosilicates and presence of carbonate- and phyllosilicate-filled veins. In this report we describe an unusual CM lithology containing beautiful aggregates of jackstraw pyrrhotites, not previously reported from any meteorite.

  5. Long-term effects of deep soil loosening on root distribution and soil physical parameters in compacted lignite mine soils

    NASA Astrophysics Data System (ADS)

    Badorreck, Annika; Krümmelbein, Julia; Raab, Thomas

    2015-04-01

    Soil compaction is a major problem of soils on dumped mining substrates in Lusatia, Germany. Deep ripping and cultivation of deep rooting plant species are considered to be effective ways of agricultural recultivation. Six years after experiment start, we studied the effect of initial deep soil loosening (i.e. down to 65 cm) on root systems of rye (Secale cereale) and alfalfa (Medicago sativa) and on soil physical parameters. We conducted a soil monolith sampling for each treatment (deep loosened and unloosened) and for each plant species (in three replicates, respectively) to determine root diameter, length density and dry mass as well as soil bulk density. Further soil physical analysis comprised water retention, hydraulic conductivity and texture in three depths. The results showed different reactions of the root systems of rye and alfalfa six years after deep ripping. In the loosened soil the root biomass of the rye was lower in depths of 20-40 cm and the root biomass of alfalfa was also decreased in depths of 20-50 cm together with a lower root diameter for both plant species. Moreover, total and fine root length density was higher for alfalfa and vice versa for rye. The soil physical parameters such as bulk density showed fewer differences, despite a higher bulk density in 30-40cm for the deep loosened rye plot which indicates a more pronounced plough pan.

  6. Distinct Distribution of Purines in CM and CR Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

    Callahan, Michael P.; Stern, Jennifer C.; Glavin, Daniel P.; Smith, Karen E.; Martin, Mildred G.; Dworkin, Jason P.

    2010-01-01

    Carbonaceous meteorites contain a diverse suite of organic molecules and delivered pre biotic organic compounds, including purines and pyrimidines, to the early Earth (and other planetary bodies), seeding it with the ingredients likely required for the first genetic material. We have investigated the distribution of nucleobases in six different CM and CR type carbonaceous chondrites, including fivc Antarctic meteorites never before analyzed for nucleobases. We employed a traditional formic acid extraction protocol and a recently developed solid phase extraction method to isolate nucleobases. We analyzed these extracts by high performance liquid chromatography with UV absorbance detection and tandem mass spectrometry (HPLC-UV -MS/MS) targeting the five canonical RNAIDNA bases and hypoxanthine and xanthine. We detected parts-per-billion levels of nucleobases in both CM and CR meteorites. The relative abundances of the purines found in Antarctic CM and CR meteorites were clearly distinct from each other suggesting that these compounds are not terrestrial contaminants. One likely source of these purines is formation by HCN oligomerization (with other small molecules) during aqueous alteration inside the meteorite parent body. The detection of the purines adenine (A), guanine (0), hypoxanthine (HX), and xanthine (X) in carbonaceous meteorites indicates that these compounds should have been available on the early Earth prior to the origin of the first genetic material.

  7. The wedge bias in reionization 21-cm power spectrum measurements

    NASA Astrophysics Data System (ADS)

    Jensen, Hannes; Majumdar, Suman; Mellema, Garrelt; Lidz, Adam; Iliev, Ilian T.; Dixon, Keri L.

    2016-02-01

    A proposed method for dealing with foreground emission in upcoming 21-cm observations from the epoch of reionization is to limit observations to an uncontaminated window in Fourier space. Foreground emission can be avoided in this way, since it is limited to a wedge-shaped region in k∥, k⊥ space. However, the power spectrum is anisotropic owing to redshift-space distortions from peculiar velocities. Consequently, the 21-cm power spectrum measured in the foreground avoidance window - which samples only a limited range of angles close to the line-of-sight direction - differs from the full redshift-space spherically averaged power spectrum which requires an average over all angles. In this paper, we calculate the magnitude of this `wedge bias' for the first time. We find that the bias amplifies the difference between the real-space and redshift-space power spectra. The bias is strongest at high redshifts, where measurements using foreground avoidance will overestimate the redshift-space power spectrum by around 100 per cent, possibly obscuring the distinctive rise and fall signature that is anticipated for the spherically averaged 21-cm power spectrum. In the later stages of reionization, the bias becomes negative, and smaller in magnitude (≲20 per cent).

  8. Ground-Based Passive Microwave Remote Sensing Observations of Soil Moisture at S and L Band with Insight into Measurement Accuracy

    NASA Technical Reports Server (NTRS)

    Laymon, Charles A.; Crosson, William L.; Jackson, Thomas J.; Manu, Andrew; Tsegaye, Teferi D.; Soman, V.; Arnold, James E. (Technical Monitor)

    2001-01-01

    Accurate estimates of spatially heterogeneous algorithm variables and parameters are required in determining the spatial distribution of soil moisture using radiometer data from aircraft and satellites. A ground-based experiment in passive microwave remote sensing of soil moisture was conducted in Huntsville, Alabama from July 1-14, 1996 to study retrieval algorithms and their sensitivity to variable and parameter specification. With high temporal frequency observations at S and L band, we were able to observe large scale moisture changes following irrigation and rainfall events, as well as diurnal behavior of surface moisture among three plots, one bare, one covered with short grass and another covered with alfalfa. The L band emitting depth was determined to be on the order of 0-3 or 0-5 cm below 0.30 cubic centimeter/cubic centimeter with an indication of a shallower emitting depth at higher moisture values. Surface moisture behavior was less apparent on the vegetated plots than it was on the bare plot because there was less moisture gradient and because of difficulty in determining vegetation water content and estimating the vegetation b parameter. Discrepancies between remotely sensed and gravimetric, soil moisture estimates on the vegetated plots point to an incomplete understanding of the requirements needed to correct for the effects of vegetation attenuation. Quantifying the uncertainty in moisture estimates is vital if applications are to utilize remotely-sensed soil moisture data. Computations based only on the real part of the complex dielectric constant and/or an alternative dielectric mixing model contribute a relatively insignificant amount of uncertainty to estimates of soil moisture. Rather, the retrieval algorithm is much more sensitive to soil properties, surface roughness and biomass.

  9. Modeling Soil Pore Oxygen in Restored Wetlands

    NASA Astrophysics Data System (ADS)

    Rubol, S.; Loecke, T.; Burgin, A. J.; Franz, T.

    2015-12-01

    Soil pore oxygen (O2) is usually modeled indirectly as a function of soil moisture. However, using soil moisture to describe the oxic /anoxic status of a soil may not be sufficient accurate, especially when soil pore O2 rapidly changes, as following hydrological forcing. As first step, we use the dataset collected in the constructed wetland near Dayton, OH, by Loecke and Burgin, to reconstruct the environmental functions and re-aeration status of the soil. The dataset consist of 24 Apogee sensors and 24 soil moisture and temperature sensors located at 10 cm depth in upland, transitional and submerged zone (see Figure 1). Data were recorded over two years at temporal interval of 30 minutes. Then, we explore the capability of existing biogeochemical models to predict metabolic activity and the soil pore O2. Figure1: Restored wetland field site with soil O2 sensors (yellow stars) in upland (red), transitional (green) and submerged (blue) zones.

  10. Remediating munitions contaminated soils

    SciTech Connect

    Shea, P.J.; Comfort, S.D.

    1995-10-01

    The former Nebraska Ordnance Plant (NOP) at Mead, NE was a military loading, assembling, and packing facility that produced bombs, boosters and shells during World War II and the Korean War (1942-1945, 1950-1956). Ordnances were loaded with 2,4,6-trinitrotoluene (TNT), amatol (TNT and NH{sub 4}NO{sub 3}), tritonal (TNT and Al) and Composition B (hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX] and TNT). Process waste waters were discharged into wash pits and drainage ditches. Soils within and surrounding these areas are contaminated with TNT, RDX and related compounds. A continuous core to 300 cm depth obtained from an NOP drainage ditch revealed high concentrations of TNT in the soil profile and substantial amounts of monoamino reduction products, 4-amino-2,6-dinitrotoluene (4ADNT) and 2-amino-4,6-dinitrotoluene (2ADNT). Surface soil contained TNT in excess of 5000 mg kg{sup -1} and is believed to contain solid phase TNT. This is supported by measuring soil solution concentrations at various soil to solution ratios (1:2 to 1:9) and obtaining similar TNT concentrations (43 and 80 mg L{sup -1}). Remediating munitions-contaminated soil at the NOP and elsewhere is of vital interest since many of the contaminants are carcinogenic, mutagenic or otherwise toxic to humans and the environment. Incineration, the most demonstrated remediation technology for munitions-containing soils, is costly and often unacceptable to the public. Chemical and biological remediation offer potentially cost-effective and more environmentally acceptable alternatives. Our research objectives are to: (a) characterize the processes affecting the transport and fate of munitions in highly contaminated soil; (b) identify effective chemical and biological treatments to degrade and detoxify residues; and (c) integrate these approaches for effective and practical remediation of soil contaminated with TNT, RDX, and other munitions residues.

  11. Changes in the properties of soils in a solonetz soil complex thirty years after reclamation

    NASA Astrophysics Data System (ADS)

    Kalinichenko, V. P.; Sharshak, V. K.; Mironchenko, S. F.; Chernenko, V. V.; Ladan, E. P.; Genev, E. D.; Illarionov, V. V.; Udalov, A. V.; Udalov, V. V.; Kippel, E. V.

    2014-04-01

    The long-term (30 year) dynamics of a solonetz soil complex composed of solonetzic light chestnut soils and chestnut solonetzes under standard conditions and with the application of agromeliorative measures are considered. When the standard zonal agricultural practice is used, the soils of the solonetzic complex have unfavorable agrophysical, chemical, and physicochemical properties and low productivity. After 30 years of the standard three-level tillage of the soils to a depth of 40-45 cm, the productivity of the biogeocenosis decreased. Thirty years after a single rotary-milling subsoil treatment of the 20- to 45-cm soil layer using a milling tool FS-1.3, there were no morphological features pointing to the restoration of the solonetzic process. The humus content in the 0-to 20-cm and 20-to 40-cm soil layers was 2.3 and 1.7%, respectively; the content of adsorbed Na+ in the 20-to 30-cm layer was 11.6% of the total exchange capacity, or 38% lower than its content in the reference soil. The additional yield reached 30-70% and more of that obtained with the standard agricultural technology used during the whole period under investigation. The method of systems biogeotechnology (systems bio-geo engineering) is proposed as a method for the preventive control of soil evolution and the maintenance of the stability and high productivity of the soil cover.

  12. Soil warming affects soil organic matter chemistry of all density fractions of a mountain forest soil

    NASA Astrophysics Data System (ADS)

    Schnecker, Jörg; Wanek, Wolfgang; Borken, Werner; Schindlbacher, Andreas

    2016-04-01

    Rising temperatures enhance microbial decomposition of soil organic matter (SOM) and increase thereby the soil CO2 efflux. Elevated microbial activity might differently affect distinct SOM pools, depending on their stability and accessibility. Soil fractions derived from density fractionation have been suggested to represent SOM pools with different turnover times and stability against microbial decomposition. We here investigated the chemical and isotopic composition of bulk soil and three different density fractions of forest soils from a long term warming experiment in the Austrian Alps. At the time of sampling the soils in this experiment had been warmed during the snow-free period for 8 consecutive years. During that time no thermal adaptation of the microbial community could be identified and CO2 release from the soil continued to be elevated by the warming treatment. Our results which included organic C content, total N content, δ13C, δ 14C, δ 15N and the chemical composition, identified by pyrolysis-GC/MS, showed no significant differences in bulk soil between warming treatment and control. The differences in the three individual fractions (free particulate organic matter, occluded particulate organic matter and mineral associated organic matter) were mostly small and the direction of warming induced change was variable with fraction and sampling depth. We did however find statistically significant effects of warming in all density fractions from 0-10 cm depth, 10-20 cm depth or both. Our results also including significant changes in the supposedly more stable mineral associated organic matter fraction where δ 13C values decreased at both sampling depths and the relative proportion of N-bearing compounds decreased at a sampling depth of 10-20 cm. All the observed changes can be attributed to an interplay of enhanced microbial decomposition of SOM and increased root litter input. This study suggests that soil warming destabilizes all density fractions of

  13. Carbon sequestration in two alpine soils on the Tibetan Plateau.

    PubMed

    Tian, Yu-Qiang; Xu, Xing-Liang; Song, Ming-Hua; Zhou, Cai-Ping; Gao, Qiong; Ouyang, Hua

    2009-09-01

    Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb-(14)C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-(14)C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb-(14)C spike, the carbon sequestration rate was determined to be 38.5 g C/m(2) per year for the forest soil and 27.1 g C/m(2) per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon (SOC) is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to "the missing carbon sink". PMID:19723249

  14. Conserving Soil.

    ERIC Educational Resources Information Center

    Soil Conservation Service (USDA), Washington, DC.

    Designed as enrichment materials for grades six through nine, this program is an interdisciplinary study of soils. As part of the program students: (1) examine soil organisms; (2) research history of local Native Americans to see how they and others have used the land and its soils; (3) investigate how soils are degraded and how they are conserved…

  15. Imaging and timing performance of 1 cm x 1 cm position-sensitive solid-state photomultiplier

    NASA Astrophysics Data System (ADS)

    Dokhale, P.; Schmall, J.; Stapels, C.; Christian, J.; Cherry, S. R.; Squillante, M. R.; Shah, K.

    2013-02-01

    We have designed and built a large-area 1cm × 1cm position-sensitive solid-state photomultiplier (PS-SSPM) for use in detector design for medical imaging applications. Our new large-area PS-SSPM concept implements resistive network between the micro-pixels, which are photodiodes operated in Geiger mode, called Geiger Photodiodes (GPDs), to provide continuous position sensitivity. Here we present imaging and timing performance of the large-area PS-SSPM for different temperatures and operating biases to find the optimum operating parameters for the device in imaging applications. A detector module was built by coupling a polished 8 × 8 LYSO array, with 1 × 1 × 20 mm3 elements, to a 1 × 1 cm2 PS-SSPM. Flood images recorded at room temperature show good crystal separation as all 64 elements were separated from each other. Cooling the device at 10 °C showed significant improvement. The device optimum bias voltage was ~ 4.5V over breakdown voltage. The coincidence timing resolution was improved significantly by increasing the operating bias, as well as by lowering the temperature to 0 °C. Results show excellent imaging performance and good timing response with a large-area PS-SSPM device.

  16. Chemical changes in agricultural soils of Korea: data review and suggested countermeasures.

    PubMed

    Jo, I S; Koh, M H

    2004-01-01

    The monitoring of chemical properties, including heavy metals, in soils is necessary if better management and remediation practices are to be established for polluted soils. The National Institute of Agricultural Science and Technology initiated a monitoring study that investigated fertility and heavy metal contents of the benchmarked soils. The study covered paddy soils, upland soils, and horticultural soils in the plastic film houses, and orchard soils throughout the Korea from 1990 to 1998. Likewise, 4047 samples of paddy and 2534 samples of plastic house in 1999 and 2000 were analyzed through the Soil Environment Conservation Act. Soil chemical properties such as pH, organic matter, available phosphate and extractable calcium, magnesium and potassium contents, and heavy metal contents such as cadmium, copper, lead, zinc, arsenic, mercury, and cobalt contents were analyzed. The study showed that the average contents of organic matter, available phosphate, and extractable potassium rapidly increased in plastic house soils than in upland or paddy soils. Two kinds of fertilizer recommendation systems were established for the study: the standard levels by national soil average data for 77 crops and the recommendation by soil test for 70 crops. Standard nitrogen fertilizer application levels for cereal crops changed from 94 kg/ha in 1960s, 99 kg/ha in 1970s, 110 kg/ha in 1980s to 90 kg/ha in 1990s. The K2O-fertilizer also changed from 67 kg/ha in 1960s, 76 kg/ha in 1970s, 92 kg/ha in 1980s, and only 44 kg/ha in 1990s. In rice paddy fields, the average contents of Cd, Cu, Pb, and Zn in surface soils (0-15 cm depth) were 0.11 mg kg(-1) (ranged from 0 to 1.01), 4.70 mg kg(-1) (0-41.59), 4.84 mg kg(-1) (0-66.44), and 4.47 mg kg(-1) (0-96.70), respectively. In the uplands, the average contents of Cd, Cu, Pb, Zn, and As in surface soils (0-15 cm depth) were 0.135 mg kg(-1) (ranged from 0 to 0.660), 2.77 mg kg(-1) (0.07-78.24), 3.47 mg kg(-1) (0-43.00), 10.70 mg kg(-1) (0.30

  17. Multiple precursors of secondary mineralogical assemblages in CM chondrites

    NASA Astrophysics Data System (ADS)

    Pignatelli, Isabella; Marrocchi, Yves; Vacher, Lionel. G.; Delon, RéMi; Gounelle, Matthieu

    2016-04-01

    We report a petrographic and mineralogical survey of tochilinite/cronstedtite intergrowths (TCIs) in Paris, a new CM chondrite considered to be the least altered CM identified to date. Our results indicate that type-I TCIs consist of compact tochilinite/cronstedtite rims surrounding Fe-Ni metal beads, thus confirming kamacite as the precursor of type-I TCIs. In contrast, type-II TCIs are characterized by complex compositional zoning composed of three different Fe-bearing secondary minerals: from the outside inwards, tochilinite, cronstedtite, and amakinite. Type-II TCIs present well-developed faces that allow a detailed morphological analysis to be performed in order to identify the precursors. The results demonstrate that type-II TCIs formed by pseudomorphism of the anhydrous silicates, olivine, and pyroxene. Hence, there is no apparent genetic relationship between type-I and type-II TCIs. In addition, the complex chemical zoning observed within type-II TCIs suggests that the alteration conditions evolved dramatically over time. At least three stages of alteration can be proposed, characterized by alteration fluids with varying compositions (1) Fe- and S-rich fluids; (2) S-poor and Fe- and Si-rich fluids; and (3) S- and Si-poor, Fe-rich fluids. The presence of unaltered silicates in close association with euhedral type-II TCIs suggests the existence of microenvironments during the first alteration stages of CM chondrites. In addition, the absence of Mg-bearing secondary minerals in Paris TCIs suggests that the Mg content increases during the course of alteration.

  18. The foreground wedge and 21-cm BAO surveys

    NASA Astrophysics Data System (ADS)

    Seo, Hee-Jong; Hirata, Christopher M.

    2016-03-01

    Redshifted H I 21 cm emission from unresolved low-redshift large-scale structure is a promising window for ground-based baryon acoustic oscillations (BAO) observations. A major challenge for this method is separating the cosmic signal from the foregrounds of Galactic and extra-Galactic origins that are stronger by many orders of magnitude than the former. The smooth frequency spectrum expected for the foregrounds would nominally contaminate only very small k∥ modes; however, the chromatic response of the telescope antenna pattern at this wavelength to the foreground introduces non-smooth structure, pervasively contaminating the cosmic signal over the physical scales of our interest. Such contamination defines a wedged volume in Fourier space around the transverse modes that is inaccessible for the cosmic signal. In this paper, we test the effect of this contaminated wedge on the future 21-cm BAO surveys using Fisher information matrix calculation. We include the signal improvement due to the BAO reconstruction technique that has been used for galaxy surveys and test the effect of this wedge on the BAO reconstruction as a function of signal to noises and incorporate the results in the Fisher matrix calculation. We find that the wedge effect expected at z = 1-2 is very detrimental to the angular diameter distances: the errors on angular diameter distances increased by 3-4.4 times, while the errors on H(z) increased by a factor of 1.5-1.6. We conclude that calibration techniques that clean out the foreground `wedge' would be extremely valuable for constraining angular diameter distances from intensity-mapping 21-cm surveys.

  19. Embolisation of Small (< 3 cm) Brain Arteriovenous Malformations

    PubMed Central

    Willinsky, R.; Goyal, M.; terBrugge, K.; Montanera, W.; Wallace*, M.G; Tymianski*, M.

    2001-01-01

    Summary The role of embolisation in the treatment of small (< 3cm) brain arteriovenous malformations (AVMs) has not been elucidated. We reviewed our experience using embolisation in the treatment of small AVMs and correlated a proposed grading system based on the angioarchitecture to the percentage obliteration achieved by embolisation. Eighty-one small AVMs in 80 patients were embolised from 1984 to 1999. The age range was from 3 to 72 years. The AVMs were given a score from 0 to 6 based on the angioarchitecture. The assigned scores were as follows: nidus (fistula = 0, < 1 cm = 1,1-3 cm = 2), type of feeding arteries (cortical = 0, perforator or choroidal = 1), number of feeding arteries (single = 0, multiple -2) and number of draining veins (single = 0\\ multiple - 1). Angiographic results based on percentage obliteration were grouped into three categories: complete, 66-99%, and 0-65%. The goal of embolisation was cure in 27 AVMs, pre-surgical in 23, pre-radiosurgery in 26, and elimination of an aneurysm in five. Embolisation achieved complete obliteration in 22 (27%) of the 81 AVMs. In the AVMs where the goal was cure, 19 (70%) of 27 were completely obliterated. In the AVMs with angioarchitecture scores of 0-2, 12 (86%) of 14 were cured, with scores of 3-4, 8 (34%) of 24 were cured and with scores of 5-6, 2 (4%) of 44 were cured. Embolisation resulted in transient morbidity of 5.0%, permanent morbidity of 2.5%, and mortality of 1.2%. There were no complications in AVMs with scores of 0-2. Embolisation is an effective treatment of small AVMs when the angioarchitecture is favourable (scores 0-2). This includes pure fistulas and AVMs with a single, pial, feeding artery. PMID:20663327

  20. Ureteroscopic treatment of larger renal calculi (>2 cm)

    PubMed Central

    Bagley, Demetrius H.; Healy, Kelly A.; Kleinmann, Nir

    2012-01-01

    Objectives To evaluate the current status of ureteroscopic lithotripsy (UL) for treating renal calculi of >2 cm, as advances in flexible ureteroscope design, accessory instrumentation and lithotrites have revolutionised the treatment of urinary calculi. While previously reserved for ureteric and small renal calculi, UL has gained an increasing role in the selective management of larger renal stone burdens. Methods We searched the available databases, including PubMed, Google Scholar, and Scopus, for relevant reports in English, and the article bibliographies to identify additional relevant articles. Keywords included ureteroscopy, lithotripsy, renal calculi, and calculi >2 cm. Retrieved articles were reviewed to consider the number of patients, mean stone size, success rates, indications and complications. Results In all, nine studies (417 patients) were eligible for inclusion. After one, two or three procedures the mean (range) success rates were 68.2 (23–84)%, 87.1 (79–91)% and 94.4 (90.1–96.7)%, respectively. Overall, the success rate was >90% with a mean of 1.2–2.3 procedures per patient. The overall complication rate was 10.3%, including six (1.4%) intraoperative and 37 (8.9%) postoperative complications, most of which were minor. The most common indications for UL were a failed previous treatment (46%), comorbidities (18.2%), and technical and anatomical factors (12.3%). Conclusions UL is safe and effective for treating large renal calculi. While several procedures might be required for total stone clearance, UL should be considered a standard approach in the urologist’s options treating renal calculi of >2 cm. PMID:26558040

  1. Recycle Requirements for NASA's 30 cm Xenon Ion Thruster

    NASA Technical Reports Server (NTRS)

    Pinero, Luis R.; Rawlin, Vincent K.

    1994-01-01

    Electrical breakdowns have been observed during ion thruster operation. These breakdowns, or arcs, can be caused by several conditions. In flight systems, the power processing unit must be designed to handle these faults autonomously. This has a strong impact on power processor requirements and must be understood fully for the power processing unit being designed for the NASA Solar Electric Propulsion Technology Application Readiness program. In this study, fault conditions were investigated using a NASA 30 cm ion thruster and a power console. Power processing unit output specifications were defined based on the breakdown phenomena identified and characterized.

  2. Performance mapping of a 30 cm engineering model thruster

    NASA Technical Reports Server (NTRS)

    Poeschel, R. L.; Vahrenkamp, R. P.

    1975-01-01

    A 30 cm thruster representative of the engineering model design has been tested over a wide range of operating parameters to document performance characteristics such as electrical and propellant efficiencies, double ion and beam divergence thrust loss, component equilibrium temperatures, operational stability, etc. Data obtained show that optimum power throttling, in terms of maximum thruster efficiency, is not highly sensitive to parameter selection. Consequently, considerations of stability, discharge chamber erosion, thrust losses, etc. can be made the determining factors for parameter selection in power throttling operations. Options in parameter selection based on these considerations are discussed.

  3. Affordable échelle spectroscopy with a 60 cm telescope

    NASA Astrophysics Data System (ADS)

    Pribulla, T.; Garai, Z.; Hambálek, L.; Kollár, V.; Komžík, R.; Kundra, E.; Nedoroščík, J.; Sekeráš, M.; Vaňko, M

    2015-09-01

    A new fiber-fed spectrograph was installed at the 60 cm telescope of the Stará Lesná Observatory. The article presents tests of its performance (spectral resolution, signal-to-noise ratio, radial-velocity stability) and reports observations of selected variable stars and exoplanet host stars. First test observations show that the spectrograph is an ideal tool to observe bright eclipsing and spectroscopic binaries but also symbiotic and nova-like stars. The radial-velocity stability (60-80 ms-1) is sufficient to study spectroscopic binaries and to detect easily the orbital motion of hot-Jupiter extrasolar planets around bright stars.

  4. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Eighteen geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  5. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were treated on five different 30 cm diameter bombardment thrusters to evaluate the effects of grid geometry variations on thruster discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. The effects on discharge chamber performance of main magnetic field changes, magnetic baffle current, cathode pole piece length and cathode position were also investigated.

  6. Performance documentation of the engineering model 30-cm diameter thruster

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.; Rawlin, V. K.

    1976-01-01

    The results of extensive testing of two 30-cm ion thrusters which are virtually identical to the 900 series Engineering Model Thruster in an ongoing 15,000-hour life test are presented. Performance data for the nominal fullpower (2650 W) operating point; performance sensitivities to discharge voltage, discharge losses, accelerator voltage, and magnetic baffle current; and several power throttling techniques (maximum Isp, maximum thrust/power ratio, and two cases in between are included). Criteria for throttling are specified in terms of the screen power supply envelope, thruster operating limits, and control stability. In addition, reduced requirements for successful high voltage recycles are presented.

  7. The 100 cm solar telescope primary mirror study

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The manufacturing impact of primary mirror configuration on the performance of a 100 cm aperture solar telescope was studied. Three primary mirror configurations were considered: solid, standard lightweight, and mushroom. All of these are of low expansion material. Specifically, the study consisted of evaluating the mirrors with regard to: manufacturing metrology, manufacturing risk factors and ultimate quality assessment. As a result of this evaluation, a performance comparison of the configurations was made, and a recommendation of mirror configuration is the final output. These evaluations, comparisons and recommendations are discussed in detail. Other investigations were completed and are documented in the appendices.

  8. Studies of dished accelerator grids for 30-cm ion thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Geometrically different sets of dished accelerator grids were tested on five 30-cm thrusters. The geometric variation of the grids included the grid-to-grid spacing, the screen and accelerator hole diameters and thicknesses, the screen and accelerator open area fractions, ratio of dish depth to the dish diameter, compensation, and aperture shape. In general, the data taken over a range of beam currents for each grid set included the minimum total accelerating voltage required to extract a given beam current and the minimum accelerator grid voltage required to prevent electron backstreaming.

  9. Control of a 30 cm diameter mercury bombardment thruster

    NASA Technical Reports Server (NTRS)

    Terdan, F. F.; Bechtel, R. T.

    1973-01-01

    Increased thruster performance has made closed-loop automatic control more difficult than previously. Specifically, high perveance optics tend to make reliable recycling more difficult. Control logic functions were established for three automatic modes of operation of a 30-cm thruster using a power conditioner console with flight-like characteristics. The three modes provide (1) automatic startup to reach thermal stability, (2) steady-state closed-loop control, and (3) the reliable recycling of the high voltages following an arc breakdown to reestablish normal operation. Power supply impedance characteristics necessary for stable operation and the effect of the magnetic baffle on the reliable recycling was studied.

  10. Radiated and conducted EMI from a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Whittlesey, A. C.; Peer, W.

    1981-01-01

    In order to properly assess the interaction of a spacecraft with the EMI environment produced by an ion thruster, the EMI environment was characterized. Therefore, radiated and conducted emissions were measured from a 30-cm mercury ion thruster. The ion thruster beam current varied from zero to 2.0 amperes and the emissions were measured from 5 KHz to 200 MHz. Several different types of antennas were used to obtain the measurements. The various measurements that were made included: magnetic field due to neutralizer/beam current loop; radiated electric fields of thruster and plume; and conducted emissions on arc discharge, neutralizer keeper and magnetic baffle lines.

  11. Endurance testing of a 30-cm Kaufman thruster

    NASA Technical Reports Server (NTRS)

    Collett, C. R.

    1973-01-01

    Results of a program to demonstrate lifetime capability of a 30-cm Kaufman ion thruster with a 6000 hour endurance test are described. Included in the program are (1) thruster fabrication, (2) design and construction of a test console containing a transistorized high frequency power processor, and control circuits which provide unattended automatic operation of the thruster, and (3) modification of a vacuum facility to incorporate a frozen mercury collector and permit unattended operation. Four tests ranging in duration from 100 to 1100 hours have been completed. These tests and the resulting thruster modifications are described. The status of the endurance test is also presented.

  12. Long lifetime hollow cathodes for 30-cm mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Kerslake, W. R.

    1976-01-01

    An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

  13. A multiple thruster array for 30-cm thrusters

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Mantenieks, M. A.

    1975-01-01

    The 3.0-m diameter chamber of the 7.6-m diameter by 21.4-m long vacuum tank at NASA LeRC was modified to permit testing of an array of up to six 30-cm thrusters with a variety of laboratory and thermal vacuum bread-board power systems. A primary objective of the Multiple Thruster Array (MTA) program is to assess the impact of multiple thruster operation on individual thruster and power processor requirements. The areas of thruster startup, steady-state operation, throttling, high voltage recycle, thrust vectoring, and shutdown are of special concern. The results of initial tests are reported.

  14. Performance capabilities of the 8-cm mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A preliminary characterization of the performance capabilities of the 8-cm thruster in order to initiate an evaluation of its application to LSS propulsion requirements is presented. With minor thruster modifications, the thrust was increased by about a factor of four while the discharge voltage was reduced from 39 to 22 volts. The thruster was operated over a range of specific impulse of 1950 to 3040 seconds and a maximum total efficiency of about 54 percent was attained. Preliminary analysis of component lifetimes, as determined by temperature and spectroscopic line intensity measurements, indicated acceptable thruster lifetimes are anticipated at the high power level operation.

  15. Status of 30 cm mercury ion thruster development

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.; King, H. J.

    1974-01-01

    Two engineering model 30-cm ion thrusters were assembled, calibrated, and qualification tested. This paper discusses the thruster design, performance, and power system. Test results include documentation of thrust losses due to doubly charged mercury ions and beam divergence by both direct thrust measurements and beam probes. Diagnostic vibration tests have led to improved designs of the thruster backplate structure, feed system, and harness. Thruster durability is being demonstrated over a thrust range of 97 to 113 mN at a specific impulse of about 2900 seconds. As of August 15, 1974, the thruster has successfully operated for over 4000 hours.

  16. The 8-CM ion thruster characterization. [mercury ion engine

    NASA Technical Reports Server (NTRS)

    Wessel, F. J.; Williamson, W. S.

    1983-01-01

    The performance capabilities of the 8 cm diameter mercury ion thruster were increased by modifying the thruster operating parameters and component hardware. The initial performance levels, representative of the Hughes/NASA Lewis Research Center Ion Auxiliary Propulsion Subsystem (IAPS) thruster, were raised from the baseline values of thrust, T = 5 mN, and specific impulse, I sub sp = 2,900s, to thrust, T = 25 mN and specific impulse, I sub sp = 4,300 s. Performance characteristics including estmates of the erosion rates of various component surfaces are presented.

  17. Human Being Imaging with cm-Wave UWB Radar

    NASA Astrophysics Data System (ADS)

    Yarovoy, A.; Zhuge, X.; Savelyev, T.; Matuzas, J.; Levitas, B.

    Possibilities of high-resolution human body imaging and concealed weapon detection using centimeter-wave microwave frequencies are investigated. Dependencies of the cross-range resolution of different imaging techniques on operational bandwidth, center frequency, imaging aperture size, and imaging topology have been studied. It has been demonstrated that the cross-range resolution of 2 cm can be achieved using frequencies below 10 GHz. These findings have been verified experimentally by producing high-resolution images of a foil-covered doll and some weapons.

  18. Development of an 8-cm engineering model thruster system

    NASA Technical Reports Server (NTRS)

    Herron, B. G.; Hyman, J., Jr.; Hopper, D. J.

    1976-01-01

    Electric propulsion has been shown to offer major advantages over the techniques currently employed for the control of earth satellites. For a user to realize these advantages, however, requires the availability of a proven, operationally flight-ready propulsion system. Currently an Engineering Model of an 8-cm ion thruster propulsion system is under development. The system includes the thruster unit with its associated reservoir, thruster gimbaling subsystem, and power processing unit. This paper describes the EM System with special emphasis on hardware design and system performance.

  19. Performance of 30-cm ion thrusters with dished accelerator grids

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.

    1973-01-01

    Thirteen sets of dished accelerator grids were tested on five different 30-cm diameter bombardment thrustors to evaluate the effects of grid geometry variations on thrustor discharge chamber performance. The dished grid parameters varied were: grid-to-grid spacing, screen and accelerator grid hole-diameter, screen and accelerator open area fraction, compensation for beam divergence losses, and accelerator grid thickness. Also investigated were the effects on discharge chamber performance of main magnetic field changes, magnetic baffle current cathode pole piece length and cathode position.

  20. Thermoacoustic imaging of fresh prostates up to 6-cm diameter

    NASA Astrophysics Data System (ADS)

    Patch, S. K.; Hanson, E.; Thomas, M.; Kelly, H.; Jacobsohn, K.; See, W. A.

    2013-03-01

    Thermoacoustic (TA) imaging provides a novel contrast mechanism that may enable visualization of cancerous lesions which are not robustly detected by current imaging modalities. Prostate cancer (PCa) is the most notorious example. Imaging entire prostate glands requires 6 cm depth penetration. We therefore excite TA signal using submicrosecond VHF pulses (100 MHz). We will present reconstructions of fresh prostates imaged in a well-controlled benchtop TA imaging system. Chilled glycine solution is used as acoustic couplant. The urethra is routinely visualized as signal dropout; surgical staples formed from 100-micron wide wire bent to 3 mm length generate strong positive signal.

  1. Soil Property Influences on Xiphinema americanum Populations as Related to Maturity of Loess-Derived Soils

    PubMed Central

    Schmitt, D. P.

    1973-01-01

    Field populations of Xiphinerna americanum around roots of Syringa vulgaris 'President Lincoln' were larger in Marshall silty clay loam, a medially developed loess soil, than in Monona silt loam, a minimally developed loess soil. Most X. amerieanum occurred in the top 15 cm of soil, with few below 30 cm. Maximum numbers occurred in August of both years in the Marshall soil, and in August 1969 and June 1970 in the Monona soil. Population fluctuations during the growing season were coincident with changes in soil moisture content. Although the population fluctuation pattern was the same at each depth tested, the adult-to-juvenile ratio increased in one soil while it decreased in the other. Numbers of X. americanum decreased as root weights decreased within a soil profile, but they were not correlated with root weights over all soils and depths. More X. americanum were recovered from the Marshall than from the Monona soil, but fibrous root weights were greater in the Monona soil. Survival of X. americanum in soil columns in growth chamber experiments was better in the Marshall than in the Monona soil. Movement and survival were different in identically textured Monona A and B horizon soils. Factors related to the ion exchange sites may affect X. americanum. PMID:19319342

  2. Soil Property Influences on Xiphinema americanum Populations as Related to Maturity of Loess-Derived Soils.

    PubMed

    Schmitt, D P

    1973-10-01

    Field populations of Xiphinerna americanum around roots of Syringa vulgaris 'President Lincoln' were larger in Marshall silty clay loam, a medially developed loess soil, than in Monona silt loam, a minimally developed loess soil. Most X. amerieanum occurred in the top 15 cm of soil, with few below 30 cm. Maximum numbers occurred in August of both years in the Marshall soil, and in August 1969 and June 1970 in the Monona soil. Population fluctuations during the growing season were coincident with changes in soil moisture content. Although the population fluctuation pattern was the same at each depth tested, the adult-to-juvenile ratio increased in one soil while it decreased in the other. Numbers of X. americanum decreased as root weights decreased within a soil profile, but they were not correlated with root weights over all soils and depths. More X. americanum were recovered from the Marshall than from the Monona soil, but fibrous root weights were greater in the Monona soil. Survival of X. americanum in soil columns in growth chamber experiments was better in the Marshall than in the Monona soil. Movement and survival were different in identically textured Monona A and B horizon soils. Factors related to the ion exchange sites may affect X. americanum. PMID:19319342

  3. Soil organic carbon mining versus priming - controls of soil organic carbon stocks along a management gradient

    NASA Astrophysics Data System (ADS)

    Blanes, M. Carmen; Reinsch, Sabine; Glanville, Helen C.; Jones, Davey L.; Carreira, José A.; Pastrana, David N.; Emmett, Bridget A.

    2015-04-01

    Soil carbon (C), nitrogen (N) and phosphorous (P) are assumed to be connected stoichiometrically and C:N(:P) ratios are frequently used to interpret the soils nutrient status. However, plants are capable of initiating the supply of nutrients by releasing rhizodeposits into the soil, thereby stimulating soil organic matter decomposition mediated by the rhizosphere microbial community. To test the relative importance of the two mechanisms across a fertility gradient in the UK we carried out a laboratory experiment. Intact soil cores from two depths (0-15 cm and 85-100 cm) were incubated and C, N and P were added in all possible combinations resulting in a total of 216 soil cores. Soil respiration was measured (1 h incubation, 10 oC) nine times over a 2 week period. Preliminary results indicate that all soils were C limited at the surface as measured as increased soil CO2 efflux. N additions increased soil respiration only marginally, whereas C+N stimulated microbial activity on the surface, and was even more pronounced in the deeper soil layer. Belowground responses to C+P were small and even smaller for N+P but similar for both soil depths. Our results indicate nutrient controls on soil organic matter turnover differ not only across a management/fertility gradient but also vertically down the soil profile.

  4. Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska

    PubMed Central

    Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-Sun; Chun, Jongsik; Lee, Yoo Kyung

    2014-01-01

    The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0–10 cm to 10–20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen ( and ). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska. PMID:24893754

  5. Intensive Eucalyptus plantation management in Brazil: Long-term effects on soil carbon dynamics across 300 sites

    NASA Astrophysics Data System (ADS)

    Cook, R. L.; Stape, J.; Binkley, D.

    2011-12-01

    Intensively managed forest plantations now cover more than 6 million hectares in Brazil, and another 20 million hectares in other tropical regions. Although aboveground biomass, and therefore carbon, is well monitored due to commercial interest, the belowground carbon dynamics and site sustainability remain poorly understood. So, how does intensive silviculture change the storage of carbon in soils? Trends in soil organic carbon from land-use change indicate that conversion from pastures to Eucalyptus plantations should maintain soil carbon stocks. However, comprehensive, long-term studies are needed to understand the variability in these trends to better manage these systems for sustainable productivity across a highly variable landscape, as well as to understand the role that soils may play in sequestering carbon for climate change mitigation. In this unique, long-term soil study, soil samples were collected in the 1980s/90s, 2001, and 2010 across 300 intensively managed Eucalyptus plantation sites located in the states of Bahia, Espirito Santo, and Sao Paulo, Brazil. Natural ecosystems for these states include Savannah-Dry Forest, Atlantic Forest, and Savanna, respectively. The sampling covered at least three complete rotations of Eucalyptus at each site; climate, past land use, productivity, and soil characteristics vary across this geographic gradient. Across the two periods, both Espirito Santo (P<0.001) and Bahia (P=0.05) showed a decrease in soil carbon concentrations, while Sao Paulo saw no change over time. For the 0-30 cm layer, plantations in Espirito Santo state had the largest decrease in soil carbon concentration up to 2001, decreasing soil carbon stocks at an average rate of 1.3 Mg C ha-1 year-1. This, however, was followed by no significant change from 2001 to 2010 which may indicate stabilization of soil carbon stocks under the new land use. The Eucalyptus in Bahia created no change in the first sampling period, but saw a decline of 0.35 Mg C ha-1

  6. Facile synthesis and enhanced electrochemical performances of Li2TiO3-coated lithium-rich layered Li1.13Ni0.30Mn0.57O2 cathode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhao, Enyue; Liu, Xiangfeng; Hu, Zhongbo; Sun, Limei; Xiao, Xiaoling

    2015-10-01

    Li2TiO3-coated Li-rich layered Li1.13Ni0.30Mn0.57O2 (0.3Li2MnO3·0.7LiNi0.5Mn0.5O2) compound has been successfully synthesized for the first time through a syn-lithiation strategy. In this approach, Ni0.35Mn0.65C2O4·xH2O precursor is first prepared by a co-precipitation method, then it is coated with TiO2 through a reaction between Ni0.35Mn0.65C2O4·xH2O and Ti(OC4H9)4, and finally Ni0.35Mn0.65C2O4rad yH2O@TiO2 is simultaneously lithiated to form Li2TiO3-coated Li-rich layered oxide. Both the cyclability and high-rate capability of Li-rich layered cathode materials have been greatly improved by Li2TiO3 coating. Meanwhile, the Li2TiO3 coating layer also reduces the polarization of the electrode and retards voltage drop during cycling. The reversible capacity of the 3 mol% Li2TiO3-coated Li-rich layered cathode material at the 100th cycle at a large current density of 100 mA/g is significantly enhanced to105 mAh/g from 78 mAh/g of the un-coated sample. The enhancements of the electrochemical performance can be largely attributed to the stabilization of the interface between the cathode and electrolyte, the three-dimensional path for Li+-ion and better conductivity after Li2TiO3 coating. It is also disclosed that the amount of Li2TiO3 coating also has a large influence on the electrochemical performances and it is necessary to optimize the specific capacity, cycling stability and rate capability through tuning the content of Li2TiO3 coating.

  7. Dissolved organic carbon (DOC) in soil extracts investigated by FT-ICR-MS

    NASA Astrophysics Data System (ADS)

    Hofmann, D.; Steffen, D.; Jablonowski, N. D.; Burauel, P.

    2012-04-01

    Soil drying and rewetting usually increases the release of xenobiotics like pesticides present in agricultural soils. Besides the effect on the release of two aged 14C-labeled pesticide residues we focus on the characterisation of simultaneously remobilized dissolved organic carbon (DOC) to gain new insights into structure and stability aspects of soil organic carbon fractions. The test soil (gleyic cambisol; Corg 1.2%, pH 7.2) was obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (0-30 cm depth; time of aging: 17 years). Soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45°C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (2000 g). This extraction procedure was repeated several individual times, for both setups. The first three individual extractions, respectively were used for further investigations. Salt was removed from samples prior analysis because of a possible quench effect in the electrospray (ESI) source by solid phase extraction (SPE) with Chromabond C18 Hydra-cartridges (Macherey-Nagel) and methanol as backextraction solvent. The so preconcentrated and desalted samples were introduced by flow injection analysis (FIA) in a fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS), equipped with an ESI source and a 7 T supra-conducting magnet (LTQ-FT Ultra, ThermoFisher Scientific). This technique is the key technique for complex natural systems attributed by their outstanding mass resolution (used 400.000 at m/z 400 Da) and mass accuracy (≤ 1ppm) by simultaneously providing molecular level details of thousands of compounds and was successful applied for the investigations of natural organic matter (NOM) different sources like marine and surface water, soil, sediment, bog and crude oil

  8. Soil carbonates and soil water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The presence of soil carbonates occurring as solidified masses or dispersed particles can alter soil water dynamics from what would be expected based on non-carbonate soil properties. Carbonate minerals in the soil can be derived from high carbonate parent material, additions in the form of carbonat...

  9. Probing patchy reionization through τ-21 cm correlation statistics

    SciTech Connect

    Meerburg, P. Daniel; Spergel, David N.; Dvorkin, Cora E-mail: dns@astro.princeton.edu

    2013-12-20

    We consider the cross-correlation between free electrons and neutral hydrogen during the epoch of reionization (EoR). The free electrons are traced by the optical depth to reionization τ, while the neutral hydrogen can be observed through 21 cm photon emission. As expected, this correlation is sensitive to the detailed physics of reionization. Foremost, if reionization occurs through the merger of relatively large halos hosting an ionizing source, the free electrons and neutral hydrogen are anticorrelated for most of the reionization history. A positive contribution to the correlation can occur when the halos that can form an ionizing source are small. A measurement of this sign change in the cross-correlation could help disentangle the bias and the ionization history. We estimate the signal-to-noise ratio of the cross-correlation using the estimator for inhomogeneous reionization τ-hat {sub ℓm} proposed by Dvorkin and Smith. We find that with upcoming radio interferometers and cosmic microwave background (CMB) experiments, the cross-correlation is measurable going up to multipoles ℓ ∼ 1000. We also derive parameter constraints and conclude that, despite the foregrounds, the cross-correlation provides a complementary measurement of the EoR parameters to the 21 cm and CMB polarization autocorrelations expected to be observed in the coming decade.

  10. Altimeter error sources at the 10-cm performance level

    NASA Technical Reports Server (NTRS)

    Martin, C. F.

    1977-01-01

    Error sources affecting the calibration and operational use of a 10 cm altimeter are examined to determine the magnitudes of current errors and the investigations necessary to reduce them to acceptable bounds. Errors considered include those affecting operational data pre-processing, and those affecting altitude bias determination, with error budgets developed for both. The most significant error sources affecting pre-processing are bias calibration, propagation corrections for the ionosphere, and measurement noise. No ionospheric models are currently validated at the required 10-25% accuracy level. The optimum smoothing to reduce the effects of measurement noise is investigated and found to be on the order of one second, based on the TASC model of geoid undulations. The 10 cm calibrations are found to be feasible only through the use of altimeter passes that are very high elevation for a tracking station which tracks very close to the time of altimeter track, such as a high elevation pass across the island of Bermuda. By far the largest error source, based on the current state-of-the-art, is the location of the island tracking station relative to mean sea level in the surrounding ocean areas.

  11. Development of 14 cm Period Wiggler at PLS

    SciTech Connect

    Kim, D.E.; Park, K.H.; Lee, H.G.; Suh, H.S.; Han, H.S.; Jung, Y.G.; Chung, C.W.

    2004-05-12

    Pohang Accelerator Laboratory (PAL) is developing a 14 cm period wiggler (MPW14) for high flux material science(HFMS) beamline. The MPW14 is a hybrid type device achieving higher peak flux density. PLS MPW14 features period of 14cm, minimum gap of 14mm, 24 full field poles, maximum flux density of 2.02 Tesla, and the total magnetic structure length of 2056mm. The peak flux density is higher compared to the other wigglers of similar pole gap and period. The high peak flux density has been achieved by using advanced new magnetic materials and optimized magnetic geometry. The magnetic performance of the MPW14 is measured using a conventional hall probe scanning system and flipping coil system. The newly developed angularly resolved flipping coil measurement system is very precise and fast. Due to its angular resolving feature, all higher order multipole contents of the MPW14 could be measured. In this article, all the developments efforts for the PLS MPW14 wiggler and the efforts for the angularly resolving flipping coil measurement system are described.

  12. Presolar grains in the CM2 chondrite Sutter's Mill

    NASA Astrophysics Data System (ADS)

    Zhao, Xuchao; Lin, Yangting; Yin, Qing-Zhu; Zhang, Jianchao; Hao, Jialong; Zolensky, Michael; Jenniskens, Peter

    2014-11-01

    The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2-4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C-anomalous grains and one O-anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C-anomalous grains and 2 ppm for presolar oxides. Thirty-one silicon carbide (SiC), five carbonaceous grains, and one Al-oxide (Al2O3) were confirmed based on their elemental compositions determined by C-N-Si and O-Si-Mg-Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2-4 shows heterogeneous distributions of presolar SiC grains (12-54 ppm) in different matrix areas, indicating that the fine-grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.

  13. Discovery and First Observations of the 21-cm Hydrogen Line

    NASA Astrophysics Data System (ADS)

    Sullivan, W. T.

    2005-08-01

    Unlike most of the great discoveries in the first decade of radio astronomy after World War II, the 21 cm hydrogen line was first predicted theoretically and then purposely sought. The story is familiar of graduate student Henk van de Hulst's prediction in occupied Holland in 1944 and the nearly simultaneous detection of the line by teams at Harvard, Leiden, and Sydney in 1951. But in this paper I will describe various aspects that are little known: (1) In van de Hulst's original paper he not only worked out possible intensities for the 21 cm line, but also for radio hydrogen recombination lines (not detected until the early 1960s), (2) in that same paper he also used Jansky's and Reber's observations of a radio background to make cosmological conclusions, (3) there was no "race" between the Dutch, Americans, and Australians to detect the line, (4) a fire that destroyed the Dutch team's equipment in March 1950 ironically did not hinder their progress, but actually speeded it up (because it led to a change of their chief engineer, bringing in the talented Lex Muller). The scientific and technical styles of the three groups will also be discussed as results of the vastly differing environments in which they operated.

  14. Power processor for a 20CM ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Schoenfeld, A. D.; Cohen, E.

    1973-01-01

    A power processor breadboard for the JPL 20CM Ion Engine was designed, fabricated, and tested to determine compliance with the electrical specification. The power processor breadboard used the silicon-controlled rectifier (SCR) series resonant inverter as the basic power stage to process all the power to the ion engine. The breadboard power processor was integrated with the JPL 20CM ion engine and complete testing was performed. The integration tests were performed without any silicon-controlled rectifier failure. This demonstrated the ruggedness of the series resonant inverter in protecting the switching elements during arcing in the ion engine. A method of fault clearing the ion engine and returning back to normal operation without elaborate sequencing and timing control logic was evolved. In this method, the main vaporizer was turned off and the discharge current limit was reduced when an overload existed on the screen/accelerator supply. After the high voltage returned to normal, both the main vaporizer and the discharge were returned to normal.

  15. Electric prototype power processor for a 30cm ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Inouye, L. Y.; Schoenfeld, A. D.

    1977-01-01

    An electrical prototype power processor unit was designed, fabricated and tested with a 30 cm mercury ion engine for primary space propulsion. The power processor unit used the thyristor series resonant inverter as the basic power stage for the high power beam and discharge supplies. A transistorized series resonant inverter processed the remaining power for the low power outputs. The power processor included a digital interface unit to process all input commands and internal telemetry signals so that electric propulsion systems could be operated with a central computer system. The electrical prototype unit included design improvement in the power components such as thyristors, transistors, filters and resonant capacitors, and power transformers and inductors in order to reduce component weight, to minimize losses, and to control the component temperature rise. A design analysis for the electrical prototype is also presented on the component weight, losses, part count and reliability estimate. The electrical prototype was tested in a thermal vacuum environment. Integration tests were performed with a 30 cm ion engine and demonstrated operational compatibility. Electromagnetic interference data was also recorded on the design to provide information for spacecraft integration.

  16. Measuring the Cosmological 21 cm Monopole with an Interferometer

    NASA Astrophysics Data System (ADS)

    Presley, Morgan E.; Liu, Adrian; Parsons, Aaron R.

    2015-08-01

    A measurement of the cosmological 21 {cm} signal remains a promising but as-of-yet unattained ambition of radio astronomy. A positive detection would provide direct observations of key unexplored epochs of our cosmic history, including the cosmic dark ages and reionization. In this paper, we concentrate on measurements of the spatial monopole of the 21 {cm} brightness temperature as a function of redshift (the “global signal”). Most global experiments to date have been single-element experiments. In this paper, we show how an interferometer can be designed to be sensitive to the monopole mode of the sky, thus providing an alternate approach to accessing the global signature. We provide simple rules of thumb for designing a global signal interferometer and use numerical simulations to show that a modest array of tightly packed antenna elements with moderately sized primary beams (FWHM of ∼ 40^\\circ ) can compete with typical single-element experiments in their ability to constrain phenomenological parameters pertaining to reionization and the pre-reionization era. We also provide a general data analysis framework for extracting the global signal from interferometric measurements (with analysis of single-element experiments arising as a special case) and discuss trade-offs with various data analysis choices. Given that interferometric measurements are able to avoid a number of systematics inherent in single-element experiments, our results suggest that interferometry ought to be explored as a complementary way to probe the global signal.

  17. Characterization of an 8-cm Diameter Ion Source System

    NASA Technical Reports Server (NTRS)

    Li, Zhongmin; Hawk, C. W.; Hawk, Clark W.; Buttweiler, Mark S.; Williams, John D.; Buchholtz, Brett

    2005-01-01

    Results of tests characterizing an 8-cm diameter ion source are presented. The tests were conducted in three separate vacuum test facilities at the University of Alabama-Huntsville, Colorado State University, and L3 Communications' ETI division. Standard ion optics tests describing electron backstreaming and total-voltage-limited impingement current behavior as a function of beam current were used as guidelines for selecting operating conditions where more detailed ion beam measurements were performed. The ion beam was profiled using an in-vacuum actuating probe system to determine the total ion current density and the ion charge state distribution variation across the face of the ion source. Both current density and ExB probes were utilized. The ion current density data were used to obtain integrated beam current, beam flatness parameters, and general beam profile shapes. The ExB probe data were used to determine the ratio of doubly to singly charged ion current. The ion beam profile tests were performed at over six different operating points that spanned the expected operating range of the DAWN thrusters being developed at L3. The characterization tests described herein reveal that the 8-cm ion source is suitable for use in (a) validating plasma diagnostic equipment, (b) xenon ion sputtering and etching studies of spacecraft materials, (c) plasma physics research, and (d) the study of ion thruster optics at varying conditions.

  18. Soil profile method for soil thermal diffusivity, conductivity and heat flux:Comparison to soil heat flux plates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diffusive heat flux at the soil surface is commonly determined as a mean value over a time period using heat flux plates buried at some depth (e.g., 5 to 8 cm) below the surface with a correction to surface flux based on the change in heat storage during the corresponding time period in the soil lay...

  19. Electrical methods of determining soil moisture content

    NASA Technical Reports Server (NTRS)

    Silva, L. F.; Schultz, F. V.; Zalusky, J. T.

    1975-01-01

    The electrical permittivity of soils is a useful indicator of soil moisture content. Two methods of determining the permittivity profile in soils are examined. A method due to Becher is found to be inapplicable to this situation. A method of Slichter, however, appears to be feasible. The results of Slichter's method are extended to the proposal of an instrument design that could measure available soil moisture profile (percent available soil moisture as a function of depth) from a surface measurement to an expected resolution of 10 to 20 cm.

  20. Soil experiment

    NASA Technical Reports Server (NTRS)

    Hutcheson, Linton; Butler, Todd; Smith, Mike; Cline, Charles; Scruggs, Steve; Zakhia, Nadim

    1987-01-01

    An experimental procedure was devised to investigate the effects of the lunar environment on the physical properties of simulated lunar soil. The test equipment and materials used consisted of a vacuum chamber, direct shear tester, static penetrometer, and fine grained basalt as the simulant. The vacuum chamber provides a medium for applying the environmental conditions to the soil experiment with the exception of gravity. The shear strength parameters are determined by the direct shear test. Strength parameters and the resistance of soil penetration by static loading will be investigated by the use of a static cone penetrometer. In order to conduct a soil experiment without going to the moon, a suitable lunar simulant must be selected. This simulant must resemble lunar soil in both composition and particle size. The soil that most resembles actual lunar soil is basalt. The soil parameters, as determined by the testing apparatus, will be used as design criteria for lunar soil engagement equipment.

  1. P-O-rich sulfide phase in CM chondrites: Constraints on its origin on the CM parent body

    NASA Astrophysics Data System (ADS)

    Zhang, Ai-Cheng; Itoh, Shoichi; Yurimoto, Hisayoshi; Hsu, Wei-Biao; Wang, Ru-Cheng; Taylor, Lawrence A.

    2016-01-01

    CM chondrites are a group of primitive meteorites that have recorded the alteration history of the early solar system. We report the occurrence, chemistry, and oxygen isotopic compositions of P-O-rich sulfide phase in two CM chondrites (Grove Mountains [GRV] 021536 and Murchison). This P-O-rich sulfide is a polycrystalline aggregate of nanometer-size grains. It occurs as isolated particles or aggregates in both CM chondrites. These grains, in the matrix and in type-I chondrules from Murchison, were partially altered into tochilinite; however, grains enclosed by Ca-carbonate are much less altered. This P-O-rich sulfide in Murchison is closely associated with magnetite, FeNi phosphide, brezinaite (Cr3S4), and eskolaite (Cr2O3). In addition to sulfur as the major component, this sulfide contains ~6.3 wt% O, ~5.4 wt% P, and minor amounts of hydrogen. Analyses of oxygen isotopes by SIMS resulted in an average δ18O value of -22.5 ‰ and an average Δ17O value of 0.2 ± 9.2 ‰ (2σ). Limited variations in both chemical compositions and electron-diffraction patterns imply that the P-O-rich sulfide may be a single phase rather than a polyphase mixture. Several features indicate that this P-O-rich sulfide phase formed at low temperature on the parent body, most likely through the alteration of FeNi metal (a) close association with other low-temperature alteration products, (b) the presence of hydrogen, (c) high Δ17O values and the presence in altered mesostasis of type-I chondrules and absence in type-II chondrules. The textural relations of the P-O-rich sulfide and other low-temperature minerals reveal at least three episodic-alteration events on the parent body of CM chondrites (1) formation of P-O-rich sulfide during sulfur-rich aqueous alteration of P-rich FeNi metal, (2) formation of Ca-carbonate during local carbonation, and (3) alteration of P-O-rich sulfide and formation of tochilinite during a period of late-stage intensive aqueous alteration.

  2. New Measurements of H2 16O Line Intensities around 8800 CM-1 and 1300 CM-1

    NASA Astrophysics Data System (ADS)

    Oudot, C.; Regalia, L.; Le Wang; Daumont, L.; Thomas, X.; von der Heyden, P.; Decatoire, D.

    2010-06-01

    A precise knowledge of spectroscopic parameters for atmospheric molecules is necessary for the control and the modelling of the Earth's atmosphere. The water vapor take a special key as it participate to the global radiative balance of the atmosphere. Our laboratory is engaged since many years in the study of H216O vapor and its isotopologues [1, 2, 3]. An important work has been already made in the spectral region of 4000 to 6600 cm-1 [3] and it continues now in the following spectral window : 6600-9000 cm-1. We have focused on the lines around 8800 cm-1, as the latest version of HITRAN database still relies on the work of Mandin et al. performed in 1988 [4, 5]. We have recorded several spectra of water vapor with our step-by-step Fourier Transform Spectrometer built in our laboratory [6, 7]. We present here our intensity measurements compared to recent literature data [8] and HITRAN2008 database. Also we have performed a study around 1300 cm-1. The precise knowledge of water vapor for this spectral range is very useful for inversion of IASI spectra. We show some comparisons between our new intensity measurements and LISA database, HITRAN2004, and recent literature data [9]. References: [1] M. Carleer, A. Jenouvrier, A.-C. Vandaele, M.-F. Mérienne, R. Colin, N. F. Zobov, O. L. Polyansky, J. Tennyson and V. A. Savin, J. Chem Phys 111 (1999) 2444-2450. [2] M.-F. Mérienne, A. Jenouvrier, C. Hermans, A.-C. Vandaele, M. Carleer, C. Clerbaux, P.-F. Coheur, R. Colin, S. Fally, M. Bachc J. Quant. Spectrosc. Rad. Trans. 82 (2003) 99-117. [3] A. Jenouvrier, L. Daumont, L. RÉgalia-Jarlot, Vl. G. Tyuterev, M. Carleer, A. C. Vandaele, S. Mikhailenko and S. Fally, JQSRT, 105 (2007) 326-355. [4] J.-Y. Mandin, J.-P. Chevillard, J.-M. Flaud, C. Camy-Peyret, Can. J. Phys, 66 (1988) 997-1011. [5] J.-Y. Mandin, J.-P. Chevillard, J.-M. Flaud, C. Camy-Peyret, J. Mol. Spectrosc, 132 (1988) 352-360. [6] J-J. Plateaux, A. Barbe and A. Delahaigue, Spectrochim. Acta, 51A (1995) 1169

  3. Water content and matric potential of soil under different soil frost conditions

    NASA Astrophysics Data System (ADS)

    Suzuki, S.; Iwata, Y.; Hiirota, T.; Hasegawa, S.; Arima, J.

    2006-12-01

    Eastern Hokkaido, where is one of the largest agricultural production regions in Japan, is characterized by low air temperature and relatively thin snow covers resulting in soil frost over the winter. However, the soil frost depth has been significantly decreasing since late 1980's due to an insulation from the cold air by a thick snow cover developing in early winter. In the current study, soil water movement under different soil frost conditions were monitored to obtain a knowledge of changes in hydraulic-regime of the agricultural production systems in the Eastern Hokkaido associated with the decreasing soil frost depth in the region. A paired soil plot experiment was conducted from Nov. 2005 to May 2006, where the frost depth was artificially enhanced by removing snow in the treatment plot and the natural condition was maintained in the control plot. The soil in the experimental field was classified as Andisol with much porosity and high drainability. In each plot, water content and matric potential were measured by TDR and thermally-insulated tensiometer, respectively. Changes in snow water equivalent volume (SWE) and soil-frost depth were manually recorded. The maximum soil-frost depth in the treatment and control plots resulted in 47 and 19 cm, respectively. In both plots, soil water content and matric potential in underlying unfrozen soil decreased with the progress of freezing front, and the direction of soil water flow between 90 and 100 cm changed from downward to upward after the onset of the soil freezing. It is of note that the matric potential at 90 cm in the treatment plot decreased down to -480 cm, while the matric potential at the same depth in the control plot was -200 cm at minimum. When the underlying unfrozen soil was most driest the soil water volume stored in a depth interval from 50 to 100 cm for the treatment and control plots was 189 and 212 mm, respectively. Further, the magnitude of upward hydraulic gradient between 90 and 100 cm in the

  4. Global 21 cm signal experiments: A designer's guide

    NASA Astrophysics Data System (ADS)

    Liu, Adrian; Pritchard, Jonathan R.; Tegmark, Max; Loeb, Abraham

    2013-02-01

    The global (i.e., spatially averaged) spectrum of the redshifted 21 cm line has generated much experimental interest lately, thanks to its potential to be a direct probe of the epoch of reionization and the dark ages, during which the first luminous objects formed. Since the cosmological signal in question has a purely spectral signature, most experiments that have been built, designed, or proposed have essentially no angular sensitivity. This can be problematic because with only spectral information, the expected global 21 cm signal can be difficult to distinguish from foreground contaminants such as galactic synchrotron radiation, since both are spectrally smooth and the latter is many orders of magnitude brighter. In this paper, we establish a systematic mathematical framework for global signal data analysis. The framework removes foregrounds in an optimal manner, complementing spectra with angular information. We use our formalism to explore various experimental design trade-offs, and find that (1) with spectral-only methods, it is mathematically impossible to mitigate errors that arise from uncertainties in one’s foreground model; (2) foreground contamination can be significantly reduced for experiments with fine angular resolution; (3) most of the statistical significance in a positive detection during the dark ages comes from a characteristic high-redshift trough in the 21 cm brightness temperature; (4) measurement errors decrease more rapidly with integration time for instruments with fine angular resolution; and (5) better foreground models can help reduce errors, but once a modeling accuracy of a few percent is reached, significant improvements in accuracy will be required to further improve the measurements. We show that if observations and data analysis algorithms are optimized based on these findings, an instrument with a 5° wide beam can achieve highly significant detections (greater than 5σ) of even extended (high Δz) reionization scenarios

  5. Phosphorus Release to Floodwater from Calcareous Surface Soils and Their Corresponding Subsurface Soils under Anaerobic Conditions.

    PubMed

    Jayarathne, P D K D; Kumaragamage, D; Indraratne, S; Flaten, D; Goltz, D

    2016-07-01

    Enhanced phosphorus (P) release from soils to overlying water under flooded, anaerobic conditions has been well documented for noncalcareous and surface soils, but little information is available for calcareous and subsurface soils. We compared the magnitude of P released from 12 calcareous surface soils and corresponding subsurface soils to overlying water under flooded, anaerobic conditions and examined the reasons for the differences. Surface (0-15 cm) and subsurface (15-30 cm) soils were packed into vessels and flooded for 8 wk. Soil redox potential and concentrations of dissolved reactive phosphorus (DRP) and total dissolved Ca, Mg, Fe, and Mn in floodwater and pore water were measured weekly. Soil test P was significantly smaller in subsurface soils than in corresponding surface soils; thus, the P release to floodwater from subsurface soils was significantly less than from corresponding surface soils. Under anaerobic conditions, floodwater DRP concentration significantly increased in >80% of calcareous surface soils and in about 40% of subsurface soils. The increase in floodwater DRP concentration was 2- to 17-fold in surface soils but only 4- to 7-fold in subsurface soils. With time of flooding, molar ratios of Ca/P and Mg/P in floodwater increased, whereas Fe/P and Mn/P decreased, suggesting that resorption and/or reprecipitation of P took place involving Fe and Mn. Results indicate that P release to floodwater under anaerobic conditions was enhanced in most calcareous soils. Surface and subsurface calcareous soils in general behaved similarly in releasing P under flooded, anaerobic conditions, with concentrations released mainly governed by initial soil P concentrations. PMID:27380087

  6. Climatic controls on soil hydraulic properties along soil chronosequences on volcanic parent material

    NASA Astrophysics Data System (ADS)

    Beal, L. K.; Lohse, K. A.; Godsey, S.; Huber, D. P.

    2013-12-01

    . We observe that θ decreases with age, and α occurs at higher tensions. Soil horizons are developed dominantly on the cinder cones. These model estimates appear to match well with preliminary field measurements. Tropical climates enhance the weathering of basaltic parent material. The mean annual precipitation in the Hawaiian site is 2500 mm, and 310 mm at COTM. Accumulation of rainfall increases the weathering rate of the parent material. Using previous work characterizing the physical characteristics of soil across the Hawaii chronosequence to model the contrasting soils, we found that the 0.3 and 20 ka Hawaii soils had similar hydraulic properties; θ values were approximately 0.45 cm3/cm3 and Ks values were 6 cm/hr. However, these Hawaiian soils contrasted and were quantitatively lower than the entire COTM chronosequence. At the 2.1 ka COTM soil, Ks was 17 cm/hr and θ was 0.52-0.65 cm3/cm3 whereas at the 13.9 ka soil, Ks was 12 cm/hr and θ was 0.52 cm3/cm3. The 0.3 ka Hawaiian soil had a 20-30% higher silt content than the 2.1 ka COTM soil. Our models help quantify rates of soil development and hydraulic properties developed through time on volcanic parent materials.

  7. Changes of Soil Aggregate C Isotopes in No-Till Corn Following Bromegrass.

    NASA Astrophysics Data System (ADS)

    Follett, R. F.; Varvel, G.; Vogel, K. P.

    2007-12-01

    studies beginning to 31, 40, and 29 %, respectively, by the end of 77 months. Weight of SOC from C4 plants was 34.8, 49.8, and 73.2 % of total SOC in the 0-5, 5-10, and 0-30 cm depths, respectively at the beginning of the study, but after 77 months of no-till corn was 47.3, 59.0, and 71.8 % of total SOC for these same depths. In summary, it is important to evaluate losses or gains of SOC under cultivation. Use of the 13C:12C ratios, as influenced by reversing the growing sequence of C3 vs. C4 plants, allows losses of older SOC from C3 plants (bromegrass) vs. that added by growing C4 plants (corn) to be determined over time and allows rates of change of the SOC associated with various soil fractions to be evaluated.

  8. Effect of cropland management and slope position on soil organic carbon pool at the North Appalachian Experimental Watersheds

    SciTech Connect

    Hao, Yueli; Lal, Rattan; Owens, Lloyd; Izaurralde, R Cesar C.; Post, W M.; Hothem, Daniel

    2002-12-01

    Soil organic matter is strongly related to soil type, landscape morphology, and soil and crop management practices. Therefore, long-term (15-36-years) effects of six cropland management systems on soil organic carbon (SOC) pool in 0-30 cm depth were studied for the period of 1939-1999 at the North Appalachian Experimental Watersheds (<3 ha, Dystric Cambisol, Haplic Luvisol, and Haplic Alisol) near Coshocton, OH, USA. Six management treatments were: (1) no tillage continuous corn with NPK (NC); (2) no tillage continuous corn with NPK and manure (NTC-M); (3) no tillage corn?soybean rotation (NTR); (4) chisel tillage corn?soybean rotation (CTR); (5) moldboard tillage with corn?wheat?meadow?meadow rotation with improved practices (MTR-I); (6) moldboard tillage with corn?wheat?meadow?meadow rotation with prevalent practices (MTR-P). The SOC pool ranged from 24.5Mgha?1 in the 32-years moldboard tillage corn (Zea mays L.)?wheat (Triticum aestivum L.)?meadow?meadow rotation with straight row farming and annual application of fertilizer (N:P:K = 5:9:17) of 56?112 kg ha?1 and cattle (Bos taurus) manure of 9Mg ha?1 as the prevalent system (MTR-P) to 65.5Mgha?1 in the 36-years no tillage continuous corn with contour row farming and annual application of 170?225 kgNha?1 and appropriate amounts of P and K, and 6?11Mgha?1 of cattle manure as the improved system (NTC-M).

  9. Efficacy of 1,3-Dichloropropene in Soil Amended with Compost and Unamended Soil

    PubMed Central

    Riegel, C.; Nelson, S. D.; Dickson, D. W.; Allen, L. H.; Peterson, L. G.

    2001-01-01

    1,3-Dichloropropene (1,3-D) is a likely alternative soil fumigant for methyl bromide. The objective was to determine root-knot nematode, Meloidogyne incognita, survival in microplots after exposure to 1,3-D for various periods of time in soil that have previously been amended with compost. The treatments were 1,3-D applied broadcast at 112 liters/ha and untreated controls in both compost-amended and unamended soil. Soil samples were collected from each microplot at 6, 24, 48, 72, and 96 hours after fumigation at three depths (0-15, 15-30, and 30-45 cm). One week after fumigation, six tomato seedlings were transplanted into each microplot and root galling was recorded 6 weeks later. Plants grown in fumigated compost-amended soil had more galls than plants from fumigated unamended soil at P ≤ 0.1. Gall indices from roots in fumigated soil amended with compost were not different from nonfumigated controls. Based on soil bioassays, the number of galls decreased with increasing time after fumigation in both compost-amended and unamended soil at 0-to-15 and 15-to-30 cm depths, but not at 30 to 45 cm deep. Higher soil water content due to the elevated levels of organic matter in the soil at these depths may have interfered with 1,3-D movement, thus reducing its efficacy. PMID:19265889

  10. The effect of soil on cork quality

    PubMed Central

    Pestana, Miguel N.; Gomes, Alberto A.

    2014-01-01

    The present work aimed to contribute for a better knowledge regarding soil features as cork quality indicators for stoppers. Cork sampling was made in eight Cork oak stands (montados de sobreiro) located in the Plio-Plistocene sedimentary formations of Península de Setúbal in southern Tagus River region. The samples used to classify the cork as stopper for wine bottles were obtained in eight cork oak stands, covering soils of different types of sandstones of the Plio-plistocene. In each stand, we randomly chose five circular plots with 30 m radius and five trees per plot with same stripping conditions determined by: dendrometric features (HD- height stipping, PBH- perimeter at breaster height), trees vegetative condition (defoliation degree); stand features (density, percentage canopy cover); site conditions (soil type and orientation). In the center of each plot a pit was open to characterize the soil profile and to classify the soil. Cork quality for stoppers was evaluated according to porosity, pores/per cm2 and cork boards thickness. The soil was characterized according to morphological soil profile features (lithology, soil profound, and soil horizons) and chemical soil surface horizon features (organic matter, pH, macro, and micronutrients availability). Based on the variables studied and using the numerical taxonomy, we settled relationships between the cork quality and some soil features. The results indicate: (1) high correlation between the cork caliber and boron, cation exchange capacity, total nitrogen, exchange acidity, and exchangeable magnesium, potassium, calcium, and sodium in soils of theirs cork oaks; (2) the cork porosity is correlated with the number of pores/cm2 and magnesium soil content; (3) the other soil features have a lower correlation with the caliber, porosity, and the number of pores per cm2. PMID:25353015

  11. The effect of soil on cork quality.

    PubMed

    Pestana, Miguel N; Gomes, Alberto A

    2014-01-01

    The present work aimed to contribute for a better knowledge regarding soil features as cork quality indicators for stoppers. Cork sampling was made in eight Cork oak stands (montados de sobreiro) located in the Plio-Plistocene sedimentary formations of Península de Setúbal in southern Tagus River region. The samples used to classify the cork as stopper for wine bottles were obtained in eight cork oak stands, covering soils of different types of sandstones of the Plio-plistocene. In each stand, we randomly chose five circular plots with 30 m radius and five trees per plot with same stripping conditions determined by: dendrometric features (HD- height stipping, PBH- perimeter at breaster height), trees vegetative condition (defoliation degree); stand features (density, percentage canopy cover); site conditions (soil type and orientation). In the center of each plot a pit was open to characterize the soil profile and to classify the soil. Cork quality for stoppers was evaluated according to porosity, pores/per cm(2) and cork boards thickness. The soil was characterized according to morphological soil profile features (lithology, soil profound, and soil horizons) and chemical soil surface horizon features (organic matter, pH, macro, and micronutrients availability). Based on the variables studied and using the numerical taxonomy, we settled relationships between the cork quality and some soil features. The results indicate: (1) high correlation between the cork caliber and boron, cation exchange capacity, total nitrogen, exchange acidity, and exchangeable magnesium, potassium, calcium, and sodium in soils of theirs cork oaks; (2) the cork porosity is correlated with the number of pores/cm(2) and magnesium soil content; (3) the other soil features have a lower correlation with the caliber, porosity, and the number of pores per cm(2). PMID:25353015

  12. An 8-cm electron bombardment thruster for auxiliary propulsion

    NASA Technical Reports Server (NTRS)

    Hudson, W. R.; Banks, B. A.

    1973-01-01

    Thruster size, beam current level, and specific impulse trade-offs are considered for mercury electron bombardment ion thrusters to be used for north-south station keeping of geosynchronous spacecraft. An 8-cm diameter thruster operating at 2750 seconds specific impulse at thrust levels of 4.4 mN (1 m1b) to 8.9 mN (2 m6b) with a design life of 20,000 hours and 10,000 cycles is being developed. The thruster will have a dished two-grid system capable of thrust vectoring of + or - 10 degrees in two orthogonal directions. A preliminary thruster has been fabricated and tested; thruster performance characteristics have been determined at 4.45, 6.68, and 8.90 millinewtons.

  13. Gravitational-wave detection using redshifted 21-cm observations

    SciTech Connect

    Bharadwaj, Somnath; Guha Sarkar, Tapomoy

    2009-06-15

    A gravitational-wave traversing the line of sight to a distant source produces a frequency shift which contributes to redshift space distortion. As a consequence, gravitational waves are imprinted as density fluctuations in redshift space. The gravitational-wave contribution to the redshift space power spectrum has a different {mu} dependence as compared to the dominant contribution from peculiar velocities. This, in principle, allows the two signals to be separated. The prospect of a detection is most favorable at the highest observable redshift z. Observations of redshifted 21-cm radiation from neutral hydrogen hold the possibility of probing very high redshifts. We consider the possibility of detecting primordial gravitational waves using the redshift space neutral hydrogen power spectrum. However, we find that the gravitational-wave signal, though present, will not be detectable on superhorizon scales because of cosmic variance and on subhorizon scales where the signal is highly suppressed.

  14. 21 cm Power Spectrum Upper Limits from PAPER-64

    NASA Astrophysics Data System (ADS)

    Shiraz Ali, Zaki; Parsons, Aaron; Pober, Jonathan; Team PAPER

    2016-01-01

    We present power spectrum results from the 64 antenna deployment of the Donald C. Backer Precision Array for Probing the Epoch of Reionization (PAPER-64). We find an upper limit of Δ2≤(22.4 mK)2 over the range 0.15cm power spectrum constraints to date. In addition, we use these results to place lower limits on the spin temperature at a redshift of 8.4. We find that the spin temperature is at least 10K for a neutral fraction between 15% and 80%. This further suggests that there was heating in the early universe through various sources such as x-ray binaries.

  15. Testing of the Kuiper Airborne Observatory 91-CM telescope

    NASA Technical Reports Server (NTRS)

    Parks, R. E.

    1979-01-01

    The 91 cm telescope of the Kuiper Airborne Observatory was tested for optical figure errors in the surface of the mirrors and misalignment of the optical components. When the present set of optical components are installed in the telescope in proper alignment, the telescope produces an image with 80% of the energy in a circle of 1.50 arc seconds in diameter; that is, a 0.11 mm spot diameter in the focal plane. The primary mirror, an f/2 parabola, was tested against a flat and has a quality that puts 80% of the energy in a 0.51 arc second diameter spot. Two principal sources account for the residual error: the tertiary folding flat and the chopping secondary. It appears that the method of mounting the folding flat causes some distortion and that the secondary mirror has some residual spherical aberration in its figure.

  16. Viscoelastic hydrodynamic interactions and anomalous CM diffusion in polymer melts

    NASA Astrophysics Data System (ADS)

    Meyer, Hendrik

    We have recently discovered that anomalous center-of-mass (CM) diffusion occurring on intermediate time scales in polymer melts can be explained by the interplay of viscoelastic and hydrodynamic interactions (VHI). The theory has been solved for unentangled melts in 3D and 2D and excellent agreement between theory and simulation is found, also for alkanes with a force field optimized from neutron scattering. The physical mechanism considers that hydrodynamic interactions are not screened: they are time dependent because of increasing viscosity before the terminal relaxation time. The VHI are generally active in melts of any topology. They are most important at early times well before the terminal relaxation time and thus affect the nanosecond time range typically observable in dynamic neutron scattering experiments. We illustrate the effects with recent molecular dynamics simulations of linear, ring and star polymers. Work performed with A.N. Semenov and J. Farago.

  17. Direct thrust measurement of a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Banks, B.; Rawlin, V.; Weigand, A. J.; Walker, J.

    1975-01-01

    A direct thrust measurement of a 30-cm diameter ion thruster was accomplished by means of a laser interferometer thrust stand. The thruster was supported in a pendulum manner by three 3.65-m long wires. Electrical power was provided by means of 18 mercury filled pots. A movable 23-button planar probe rake was used to determine thrust loss due to ion beam divergence. Values of thrust, thrust loss due to ion beam divergence, and thrust loss due to multiple ionization were measured for ion beam currents ranging from 0.5 A to 2.5 A. Measured thrust values indicate an accuracy of approximately 1% and are in good agreement with thrust values calculated by indirect measurements.

  18. Developing an Interferometer to Measure the Global 21cm Monopole

    NASA Astrophysics Data System (ADS)

    Domagalski, Rachel; Patra, Nipanjana; Day, Cherie; Parsons, Aaron

    2016-01-01

    When radio interferometers observe over very small fields of view, they cannot measure the monopole mode of the sky. However, when the field of view extends to a large region of the sky, it becomes possible to use an measure the monopole with an interferometer. We are currently developing such an interferometer at UC Berkeley's Radio Astronomy Lab (RAL) with the goal of measuring the early stages of the Epoch of Reionization by probing the sky for the global 21cm signal between 50 and 100 MHz, and we have deployed a preliminary version of this experiment in Colorado. We present the current status of the interferometer, the future development plans, and some measurements taken in July of 2015. These measurements demonstrate performance of the analog signal chain of the interferometer as well as the RFI environment of the deployment site in Colorado.

  19. Cosmic (Super)String Constraints from 21 cm Radiation

    SciTech Connect

    Khatri, Rishi; Wandelt, Benjamin D.

    2008-03-07

    We calculate the contribution of cosmic strings arising from a phase transition in the early Universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z{>=}30. Future experiments can exploit this effect to constrain the cosmic string tension G{mu} and probe virtually the entire brane inflation model space allowed by current observations. Although current experiments with a collecting area of {approx}1 km{sup 2} will not provide any useful constraints, future experiments with a collecting area of 10{sup 4}-10{sup 6} km{sup 2} covering the cleanest 10% of the sky can, in principle, constrain cosmic strings with tension G{mu} > or approx. 10{sup -10}-10{sup -12} (superstring/phase transition mass scale >10{sup 13} GeV)

  20. Cosmic (Super)String Constraints from 21 cm Radiation.

    PubMed

    Khatri, Rishi; Wandelt, Benjamin D

    2008-03-01

    We calculate the contribution of cosmic strings arising from a phase transition in the early Universe, or cosmic superstrings arising from brane inflation, to the cosmic 21 cm power spectrum at redshifts z > or =30. Future experiments can exploit this effect to constrain the cosmic string tension G mu and probe virtually the entire brane inflation model space allowed by current observations. Although current experiments with a collecting area of approximately 1 km2 will not provide any useful constraints, future experiments with a collecting area of 10(4)-10(6) km2 covering the cleanest 10% of the sky can, in principle, constrain cosmic strings with tension G mu > or = 10(-10)-10(-12) (superstring/phase transition mass scale >10(13) GeV). PMID:18352691

  1. Hollow cathode restartable 15 cm diameter ion thruster

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1973-01-01

    The effects of substituting high perveance dished grids for low perveance flat ones on performance variables and plasma properties within a 15 cm modified SERT II thruster are discussed. Results suggest good performance may be achieved as an ion thruster is throttled if the screen grid transparency is decreased with propellant flow rate. Thruster startup tests, which employ a pulsed high voltage tickler electrode between the keeper and the cathode to initiate the discharge, are described. High startup reliability at cathode tip temperatures of about 500 C without excessive component wear over 2000 startup cycles is demonstrated. Testing of a single cusp magnetic field concept of discharge plasma containment is discussed. A theory which explains the observed behavior of the device is presented and proposed thruster modifications and future testing plans are discussed.

  2. Forecasted 21 cm constraints on compensated isocurvature perturbations

    SciTech Connect

    Gordon, Christopher; Pritchard, Jonathan R.

    2009-09-15

    A 'compensated' isocurvature perturbation consists of an overdensity (or underdensity) in the cold dark matter which is completely cancelled out by a corresponding underdensity (or overdensity) in the baryons. Such a configuration may be generated by a curvaton model of inflation if the cold dark matter is created before curvaton decay and the baryon number is created by the curvaton decay (or vice versa). Compensated isocurvature perturbations, at the level producible by the curvaton model, have no observable effect on cosmic microwave background anisotropies or on galaxy surveys. They can be detected through their effect on the distribution of neutral hydrogen between redshifts 30-300 using 21 cm absorption observations. However, to obtain a good signal to noise ratio, very large observing arrays are needed. We estimate that a fast Fourier transform telescope would need a total collecting area of about 20 square kilometers to detect a curvaton generated compensated isocurvature perturbation at more than 5 sigma significance.

  3. Power processor for a 30cm ion thruster

    NASA Technical Reports Server (NTRS)

    Biess, J. J.; Inouye, L. Y.

    1974-01-01

    A thermal vacuum power processor for the NASA Lewis 30cm Mercury Ion Engine was designed, fabricated and tested to determine compliance with electrical specifications. The power processor breadboard used the silicon controlled rectifier (SCR) series resonant inverter as the basic power stage to process all the power to an ion engine. The power processor includes a digital interface unit to process all input commands and internal telemetry signals so that operation is compatible with a central computer system. The breadboard was tested in a thermal vacuum environment. Integration tests were performed with the ion engine and demonstrate operational compatibility and reliable operation without any component failures. Electromagnetic interference data were also recorded on the design to provide information on the interaction with total spacecraft.

  4. Astronaut Risk Levels During Crew Module (CM) Land Landing

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly S.; Littell, Justin

    2007-01-01

    The NASA Engineering Safety Center (NESC) is investigating the merits of water and land landings for the crew exploration vehicle (CEV). The merits of these two options are being studied in terms of cost and risk to the astronauts, vehicle, support personnel, and general public. The objective of the present work is to determine the astronaut dynamic response index (DRI), which measures injury risks. Risks are determined for a range of vertical and horizontal landing velocities. A structural model of the crew module (CM) is developed and computational simulations are performed using a transient dynamic simulation analysis code (LS-DYNA) to determine acceleration profiles. Landing acceleration profiles are input in a human factors model that determines astronaut risk levels. Details of the modeling approach, the resulting accelerations, and astronaut risk levels are provided.

  5. An H I 21-cm line survey of evolved stars

    NASA Astrophysics Data System (ADS)

    Gérard, E.; Le Bertre, T.; Libert, Y.

    2011-12-01

    The HI line at 21 cm is a tracer of circumstellar matter around AGB stars, and especially of the matter located at large distances (0.1-1 pc) from the central stars. It can give unique information on the kinematics and on the physical conditions in the outer parts of circumstellar shells and in the regions where stellar matter is injected into the interstellar medium. However this tracer has not been much used up to now, due to the difficulty of separating the genuine circumstellar emission from the interstellar one. With the Nançay Radiotelescope we are carrying out a survey of the HI emission in a large sample of evolved stars. We report on recent progresses of this long term programme, with emphasis on S-type stars.

  6. Wilhelm Tempel and his 10.8-cm Steinheil Telescope

    NASA Astrophysics Data System (ADS)

    Bianchi, Simone; Gasperini, Antonella; Galli, Daniele; Palla, Francesco; Brenni, Paolo; Giatti, Anna

    2010-03-01

    The German astronomer Ernst Wilhelm Leberecht Tempel (1821-1889) owed most of his successes to a 10.8-cm Steinheil refractor, which he bought in 1858. A lithographer, without an academic foundation, but with a strong passion for astronomy, Tempel had sharp eyesight and a talent for drawing, and he discovered with his telescope many celestial objects, including asteroids, comets (most notably, 9 P/Tempel 1) and the Merope Nebula in the Pleiades. Tempel carried his telescope with him throughout his moves in France and Italy. The telescope is now conserved in Florence, at the Arcetri Astrophysical Observatory, where Tempel was astronomer from 1875 until the end of his life. Using unpublished material from the Arcetri Historical Archive, as well as documents from other archives and published material, we trace the history of the telescope and its use during and after Tempel's life, and describe its recent rediscovery and status.

  7. Autumn at Titan's South Pole: The 220 cm-1 Cloud

    NASA Astrophysics Data System (ADS)

    Jennings, D. E.; Cottini, V.; Achterberg, R. K.; Anderson, C. M.; Flasar, F. M.; de Kok, R. J.; Teanby, N. A.; Coustenis, A.; Vinatier, S.

    2015-10-01

    Beginning in 2012 an atmospheric cloud known by its far-infrared emission has formed rapidly at Tit an's South Pole [1, 2]. The build-up of this condensate is a result of deepening temperatures and a gathering of gases as Winter approaches. Emission from the cloud in the south has been doubling each year since 2012, in contrast to the north where it has halved every 3.8 years since 2004. The morphology of the cloud in the south is quite different from that in the north. In the north, the cloud has extended over the whole polar region beyond 55 N, whereas in the south the cloud has been confined to within about 10 degrees of the pole. The cloud in the north has had the form of a uniform hood, whereas the southern cloud has been much more complex. A map from December 2014,recorded by the Composite Infrared Spectrometer (CIRS) on Cassini, showed the 220 cm-1 emission coming from a distinct ring with a maximum at about 80 S. In contrast, emissions from the gases HC3N, C4H2 and C6H6 peaked near the pole and had a ring at 70 S. The 220 cm-1 ring at 80 S coincided with the minimum in the gas emission pattern. The80 S condensate ring encompassed the vortex cloud seen by the Cassini Imaging Science Subsystem (ISS) and Visible and Infrared Mapping Spectrometer (VIMS)[3, 4]. Both the 220 cm-1 ring and the gas "bull's-eye" pattern were centered on a point that was shifted from the geographic South Pole by 4 degrees in the direction of the Sun. This corresponds to the overall tilt of Titan's atmosphere discovered from temperature maps early in the Cassini mission by Achterberg et al. [5]. The tilt may be reinforced by the presumably twice-yearly (north and south) spin-up of the atmosphere at the autumnal pole. The bull's-eye pattern of the gas emissions can be explained by the retrieved abundance distributions, which are maximum near the pole and decrease sharply toward lower latitudes, together with temperatures that are minimum at the pole and increase toward lower latitudes

  8. Rb-Sr studies of CI and CM chondrites

    NASA Technical Reports Server (NTRS)

    Mittlefehldt, D. W.; Wetherill, G. W.

    1979-01-01

    Rb-Sr whole rock analyses have been performed on 2 CI and 3 CM chondrites. Four of these stones (Ivuna, Orgueil, Cold Bokkeveld and Erakot) were previously studied in this laboratory and were shown to be discordant from a 4.6 Gyr isochron. The fifth, Murchison, was not previously studied. The new data support the discordance of the first four stones, and indicate that Murchison is also discordant. Studies of Sr isotope ratios in unspiked Orgueil show that the discordance is not due to inhomogeneities in the Sr-84/Sr-86 ratio caused by incomplete mixing of nucleosynthesis products. In order to gauge the effects of weathering, two leaching experiments were performed on fresh, interior samples of Murchison; one for a period of 1.5 hr and the other for 117 hr. The results indicate that the relative solubility of nonradiogenic Sr is approximately twice that of Rb and radiogenic Sr is more soluble than the nonradiogenic Sr.

  9. The Murchison Widefield Array 21 cm Power Spectrum Analysis Methodology

    NASA Astrophysics Data System (ADS)

    Jacobs, Daniel C.; Hazelton, B. J.; Trott, C. M.; Dillon, Joshua S.; Pindor, B.; Sullivan, I. S.; Pober, J. C.; Barry, N.; Beardsley, A. P.; Bernardi, G.; Bowman, Judd D.; Briggs, F.; Cappallo, R. J.; Carroll, P.; Corey, B. E.; de Oliveira-Costa, A.; Emrich, D.; Ewall-Wice, A.; Feng, L.; Gaensler, B. M.; Goeke, R.; Greenhill, L. J.; Hewitt, J. N.; Hurley-Walker, N.; Johnston-Hollitt, M.; Kaplan, D. L.; Kasper, J. C.; Kim, HS; Kratzenberg, E.; Lenc, E.; Line, J.; Loeb, A.; Lonsdale, C. J.; Lynch, M. J.; McKinley, B.; McWhirter, S. R.; Mitchell, D. A.; Morales, M. F.; Morgan, E.; Neben, A. R.; Thyagarajan, N.; Oberoi, D.; Offringa, A. R.; Ord, S. M.; Paul, S.; Prabu, T.; Procopio, P.; Riding, J.; Rogers, A. E. E.; Roshi, A.; Udaya Shankar, N.; Sethi, Shiv K.; Srivani, K. S.; Subrahmanyan, R.; Tegmark, M.; Tingay, S. J.; Waterson, M.; Wayth, R. B.; Webster, R. L.; Whitney, A. R.; Williams, A.; Williams, C. L.; Wu, C.; Wyithe, J. S. B.

    2016-07-01

    We present the 21 cm power spectrum analysis approach of the Murchison Widefield Array Epoch of Reionization project. In this paper, we compare the outputs of multiple pipelines for the purpose of validating statistical limits cosmological hydrogen at redshifts between 6 and 12. Multiple independent data calibration and reduction pipelines are used to make power spectrum limits on a fiducial night of data. Comparing the outputs of imaging and power spectrum stages highlights differences in calibration, foreground subtraction, and power spectrum calculation. The power spectra found using these different methods span a space defined by the various tradeoffs between speed, accuracy, and systematic control. Lessons learned from comparing the pipelines range from the algorithmic to the prosaically mundane; all demonstrate the many pitfalls of neglecting reproducibility. We briefly discuss the way these different methods attempt to handle the question of evaluating a significant detection in the presence of foregrounds.

  10. Carma 1 CM Line Survey of Orion-Kl

    NASA Astrophysics Data System (ADS)

    Friedel, Douglas; Looney, Leslie; Corby, Joanna F.; Remijan, Anthony

    2015-06-01

    We have conducted the first 1 cm (27-35 GHz) line survey of the Orion-KL region by an array. With a primary beam of ˜4.5 arcminutes, the survey looks at a region ˜166,000 AU (0.56 pc) across. The data have a resolution of ˜6 arcseconds on the sky and 97.6 kHz(1.07-0.84 km/s) in frequency. This region of frequency space is much less crowded than at 3mm or 1mm frequencies and contains the fundamental transitions of several complex molecular species, allowing us to probe the largest extent of the molecular emission. We present the initial results, and comparison to 3mm results, from several species including, dimethyl ether [(CH_3)_2O], ethyl cyanide [C_2H_5CN], acetone [(CH_3)_2CO], SO, and SO_2.

  11. HIBAYES: Global 21-cm Bayesian Monte-Carlo Model Fitting

    NASA Astrophysics Data System (ADS)

    Zwart, Jonathan T. L.; Price, Daniel; Bernardi, Gianni

    2016-06-01

    HIBAYES implements fully-Bayesian extraction of the sky-averaged (global) 21-cm signal from the Cosmic Dawn and Epoch of Reionization in the presence of foreground emission. User-defined likelihood and prior functions are called by the sampler PyMultiNest (ascl:1606.005) in order to jointly explore the full (signal plus foreground) posterior probability distribution and evaluate the Bayesian evidence for a given model. Implemented models, for simulation and fitting, include gaussians (HI signal) and polynomials (foregrounds). Some simple plotting and analysis tools are supplied. The code can be extended to other models (physical or empirical), to incorporate data from other experiments, or to use alternative Monte-Carlo sampling engines as required.

  12. Translation Optics for 30 cm Ion Engine Thrust Vector Control

    NASA Technical Reports Server (NTRS)

    Haag, Thomas

    2002-01-01

    Data were obtained from a 30 cm xenon ion thruster in which the accelerator grid was translated in the radial plane. The thruster was operated at three different throttle power levels, and the accelerator grid was incrementally translated in the X, Y, and azimuthal directions. Plume data was obtained downstream from the thruster using a Faraday probe mounted to a positioning system. Successive probe sweeps revealed variations in the plume direction. Thruster perveance, electron backstreaming limit, accelerator current, and plume deflection angle were taken at each power level, and for each accelerator grid position. Results showed that the thruster plume could easily be deflected up to six degrees without a prohibitive increase in accelerator impingement current. Results were similar in both X and Y direction.

  13. 5 CM OH absorption toward the megamaser galaxy IC 4553

    NASA Astrophysics Data System (ADS)

    Henkel, C.; Guesten, R.; Batrla, W.

    1986-11-01

    Absorption in the 2Π3/2 J = 5/2 main line of OH at 6035 MHz, 120K above the ground state, is reported from the OH megamaser galaxy IC 4553 (Arp 220). An upper limit is given for Mrk 231. For IC 4553, the authors derive an OH rotation temperature Trot ≡ 45K between the 2Π3/2 J = 5/2 and 3/2 ground levels, that is ≡30% below the dust temperature. Potential pumping mechanisms for the inversion of the ground state doublet are discussed and it is argued that the most likely OH excitation scenario involves pumping by FIR photons (79, 119 μm) and centimeter wave photons (5, 6 cm).

  14. Very Large Array observations of Uranus at 2. 0 cm

    SciTech Connect

    Berge, G.L.; Muhleman, D.O.; Linfield, R.P.

    1988-07-01

    Radio observations of Uranus obtained at 2.0 cm with the B configuration of the VLA during April 1985 are reported. The calibration and data-reduction procedures are described in detail, and the results are presented in tables, maps, and graphs and compared with IRIS 44-micron observations (Hanel et al., 1986). Features discussed include highest brightness centered on the pole rather than on the subearth point, a decrease in brightness temperature (by up to 9 K) at latitudes between -20 and -50 deg (well correlated with the IRIS data), and disk-center position (corrected for the observed radio asymmetry) in good agreement with that found on the basis of the outer contours of the image. 15 references.

  15. Stratospheric measurements of continuous absorption near 2400 cm(-1).

    PubMed

    Rinsland, C P; Smith, M A; Russell Iii, J M; Park, J H; Farmer, C B

    1981-12-15

    Solar occultation spectra obtained with a balloon-borne interferometer have been used to study continuous absorption by N(2) and CO(2) near 2400 cm(-1) in the lower stratosphere. Synthetic continuum transmittances, calculated from published coefficients for far-wing absorption by CO(2) lines and for pressure-induced absorption by the fundamental band of N(2), are in fair agreement with the observed stratospheric values. The continuum close to the nu(3) R-branch band head of CO(2) is sensitive to the CO(2) far-wing line shape. Therefore, given highly accurate knowledge of the N(2) continuum from laboratory data, high-resolution stratospheric spectra provide a sensitive means for in situ testing of various air-broadened CO(2) line shapes at low temperatures. PMID:20372347

  16. Dynamics of aggregate stability and soil organic C distribution as affected by climatic aggressiveness: a mesocosm approach

    NASA Astrophysics Data System (ADS)

    Pellegrini, Sergio; Elio Agnelli, Alessandro; Costanza Andrenelli, Maria; Barbetti, Roberto; Castelli, Fabio; Costantini, Edoardo A. C.; Lagomarsino, Alessandra; Pasqui, Massimiliano; Tomozeiu, Rodica; Razzaghi, Somayyeh; Vignozzi, Nadia

    2014-05-01

    In the framework of a research project aimed at evaluating the adaptation scenarios of the Italian agriculture to the current climate change, a mesocosm experiment under controlled conditions was set up for studying the dynamics of soil aggregate stability and organic C in different size fractions. Three alluvial loamy soils (BOV - Typic Haplustalfs coarse-loamy; CAS - Typic Haplustalfs fine-loamy; MED - Typic Hapludalfs fine-loamy) along a climatic gradient (from dryer to moister pedoclimatic conditions) in the river Po valley (northern Italy), under crop rotation for animal husbandry from more than 40 years, were selected. The Ap horizons (0-30cm) were taken and placed in 9 climatic chambers under controlled temperature and rainfall. Each soil was subjected to three different climate scenarios in terms of erosivity index obtained by combining Modified Fournier and Bagnouls-Gaussen indexes: i) typical (TYP), the median year of each site related to the 1961-1990 reference period; ii) maximum aggressive year (MAX) observed in the same period, and iii) the simulated climate (SIM), obtained by projections of climate change precipitation and temperature for the period 2021-2050 as provided by the IPCC-A1B emission scenario. In the climatic chambers the year climate was reduced to six months. The soils were analyzed for particle size distribution, aggregate stability by wet and dry sieving, and organic C content at the beginning and at the end of the trial. The soils showed different behaviour in terms of aggregate stability and dynamics of organic C in the diverse size fractions. The soils significantly differed in terms of initial mean weight diameter (MWD) (CAS>MED>BOV). A general reduction of MWD in all sites was observed at the end of the experiment, with the increase of the smallest aggregate fractions (0.250-0.05 mm). In particular, BOV showed the maximum decrease of the aggregate stability and MED the lowest. C distribution in aggregate fractions significantly

  17. 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.

  18. Performance of a novel 43-cm x 43-cm flat-panel detector with CsI:Tl scintillator

    NASA Astrophysics Data System (ADS)

    Yamazaki, Tatsuya; Tamura, Tomoyuki; Nokita, Makoto; Okada, Satoshi; Hayashida, Shinsuke; Ogawa, Yoshihiro

    2004-05-01

    We have developed a novel flat-panel detector with CsI:Tl scintillator. The detector consists of a single piece 43cm x 43cm amorphous silicon thin-film transistor (TFT) array with MIS (metal-insulator-semiconductor) photoelectric converter having a pixel pitch of 160μm coated with a needle-like crystal CsI:Tl scintillator. Signal chain was totally revised from current detector utilizing an innovative sensor technology. The novel detector and current detector were equipped to a digital radiography system allowing a quantitative and comparative study. Results show that the novel detector has a linear response covering the radiographic exposure range. It has a moderate modulation transfer function (MTF) sufficient to the radiography tasks and effective to suppress the aliasing. The detective quantum efficiency (DQE) was almost twice than the current detector. The result of contrast-detail phantom exposed with a 1/2x dose level is equivalent to that of current detector with a 1x dose level. These results show that performance of novel detector is superior to and expected to reduce the patient dose in half than current detector due to higher DQE and innovative sensor technology.

  19. A simple model of carbon in the soil profile for agricultural soils in Northwestern Europe

    NASA Astrophysics Data System (ADS)

    Taghizadeh-Toosi, Arezoo; Hutchings, Nicholas J.; Vejlin, Jonas; Christensen, Bent T.; Olesen, Jørgen E.

    2014-05-01

    World soil carbon (C) stocks are second to those in the ocean, and represent three times as much C as currently present in the atmosphere. The amount of C in soil may play a significant role in carbon exchanges between the atmosphere and the terrestrial environment. The C-TOOL model is a three-pool linked soil organic carbon (SOC) model in well-drained mineral soils under agricultural land management to allow generalized parameterization for estimating effects of management measures at medium to long time scales for the entire soil profile (0-100 cm). C-TOOL has been developed to enable simulations of SOC turnover in soil using temperature dependent first order kinetics for describing decomposition. Compared with many other SOC models, C-TOOL applies a less complicated structure, which facilitates easier calibration, and it requires only few inputs (i.e., average monthly air temperature, soil clay content,soil carbon-to-nitrogen ratio, and C inputs to the soil from plants and other sources). C-TOOL was parameterized using SOC and radiocarbon data from selected long-term field treatments in United Kingdom, Sweden and Denmark. However, less data were available for evaluation of subsoil C (25-100 cm) from the long-term experiments applied. In Denmark a national 7×7 km grid net was established in 1986 for soil C monitoring down to 100 cm depth. The results of SOC showed a significant decline from 1997 to 2009 in the 0-50 cm soil layer. This was mainly attributed to changes in the 25-50 cm layer, where a decline in SOC was found for all soil texture types. Across the period 1986 to 2009 there was clear tendency for increasing SOC on the sandy soils and reductions on the loamy soils. This effect is linked to land use, since grasslands and dairy farms are more abundant in the western parts of Denmark, where most of the sandy soils are located. The results and the data from soil monitoring have been used to validate the C-TOOL modelling approach used for accounting of

  20. A simple procedure for estimating soil porosity

    NASA Astrophysics Data System (ADS)

    Emmet-Booth, Jeremy; Forristal, Dermot; Fenton, Owen; Holden, Nick

    2016-04-01

    Soil degradation from mismanagement is of international concern. Simple, accessible tools for rapidly assessing impacts of soil management are required. Soil structure is a key component of soil quality and porosity is a useful indicator of structure. We outline a version of a procedure described by Piwowarczyk et al. (2011) used to estimate porosity of samples taken during a soil quality survey of 38 sites across Ireland as part of the Government funded SQUARE (Soil Quality Assessment Research) project. This required intact core (r = 2.5 cm, H = 5cm) samples taken at 5-10 cm and 10-20 cm depth, to be covered with muslin cloth at one end and secured with a jubilee clip. Samples were saturated in sealable water tanks for ≈ 64 hours, then allowed to drain by gravity for 24 hours, at which point Field Capacity (F.C.) was assumed to have been reached, followed by oven drying with weight determined at each stage. This allowed the calculation of bulk density and the estimation of water content at saturation and following gravitational drainage, thus total and functional porosity. The assumption that F.C. was reached following 24 hours of gravitational drainage was based on the Soil Moisture Deficit model used in Ireland to predict when soils are potentially vulnerable to structural damage and used nationally as a management tool. Preliminary results indicate moderately strong, negative correlations between estimated total porosity at 5-10 cm and 10-20 cm depth (rs = -0.7, P < 0.01 in both cases) and soil quality scores of the Visual Evaluation of Soil Structure (VESS) method which was conducted at each survey site. Estimated functional porosity at 5-10 cm depth was found to moderately, negatively correlate with VESS scores (rs = - 0.5, P < 0.05). This simple procedure requires inexpensive equipment and appears useful in indicating porosity of a large quantity of samples taken at numerous sites or if done periodically, temporal changes in porosity at a field scale

  1. Effect of Thickness of a Water Repellent Soil Layer on Soil Evaporation Rate

    NASA Astrophysics Data System (ADS)

    Ahn, S.; Im, S.; Doerr, S.

    2012-04-01

    A water repellent soil layer overlying wettable soil is known to affect soil evaporation. This effect can be beneficial for water conservation in areas where water is scarce. Little is known, however, about the effect of the thickness of the water repellent layer. The thickness of this layer can vary widely, and particularly after wildfire, with the soil temperature reached and the duration of the fire. This study was conducted to investigate the effect of thickness of a top layer of water repellent soil on soil evaporation rate. In order to isolate the thickness from other possible factors, fully wettable standard sand (300~600 microns) was used. Extreme water repellency (WDPT > 24 hours) was generated by 'baking' the sand mixed with oven-dried pine needles (fresh needles of Pinus densiflora) at the mass ratio of 1:13 (needle:soil) at 185°C for 18 hours. The thicknesses of water repellent layers were 1, 2, 3 and 7 cm on top of wettable soil. Fully wettable soil columns were prepared as a control. Soil columns (8 cm diameter, 10 cm height) were covered with nylon mesh. Tap water (50 ml, saturating 3 cm of a soil column) was injected with hypoderm syringes from three different directions at the bottom level. The injection holes were sealed with hot-melt adhesive immediately after injection. The rate of soil evaporation through the soil surface was measured by weight change under isothermal condition of 40°C. Five replications were made for each. A trend of negative correlation between the thickness of water repellent top layer and soil evaporation rate is discussed in this contribution.

  2. Antimony release from contaminated mine soils and its migration in four typical soils using lysimeter experiments.

    PubMed

    Shangguan, Yu-Xian; Zhao, Long; Qin, Yusheng; Hou, Hong; Zhang, Naiming

    2016-11-01

    Antimony (Sb) can pose great risks to the environment in mining and smelting areas. The migration of Sb in contaminated mine soil was studied using lysimeter experiments. The exchangeable concentration of soil Sb decreased with artificial leaching. The concentrations of Sb retained in the subsoil layers (5-25cm deep) were the highest for Isohumosol and Ferrosol and the lowest for Sandy soil. The Sb concentrations in soil solutions decreased with soil depth, and were adequately simulated using a logarithmic function. The Sb migration pattern in Sandy soil was markedly different from the patterns in the other soils which suggested that Sb may be transported in soil colloids. Environmental factors such as water content, soil temperature, and oxidation-reduction potential of the soil had different effects on Sb migration in Sandy soil and Primosol. The high Fe and Mn contents in Ferrosol and Isohumosol significantly decreased the mobility of Sb in these soils. The Na and Sb concentrations in soils used in the experiments positively correlated with each other (P<0.01). The Sb concentrations in soil solutions, the Sb chemical fraction patterns, and the Sb/Na ratios decreased in the order Sandy soil>Primosol>Isohumosol>Ferrosol, and we concluded that the Sb mobility in the soils also decreased in that order. PMID:27395817

  3. Soil Moisture Changes in the Russian Federation: In Situ Data

    NASA Astrophysics Data System (ADS)

    Speranskaya, N. A.

    2009-04-01

    Soil moisture observations in the USSR began the middle of 1950s. At the peak of the network extent (in the middle of 1980s) more than 2000 stations performed these observations operated over Russia. Since that time the number of stations in this network was significantly reduced, especially at soil plots with natural vegetation. Therefore, in this study soil moisture changes over Russia during 1970-2000 (2001) are presented using the data of only 120 long-term stations. For the European part of Russia, it is concluded that: (1) Soil moisture changes within the upper 0-10 and 0-20 cm have no systematic component. Only when the thicker layers (starting with the upper 50 cm) are used, systematic changes (trends) can be found. That is why soil moisture of the upper 20 cm layer cannot be considered as characteristic of a moistening regime of the active soil layer. (2) Over most of non-boreal European Russia, soil moisture increase is observed for layers 0-50 and 0-100 cm both in spring and during the summer (i.e., during the entire growing period). Moreover, trends in soil moisture for the upper meter of soil (layer 0-100 cm) are more apparent when compared to those in layer 0-50 cm. (3) Only in the zone of mixed and broad-leaved forest, areas of decreasing levels of soil moisture are observed during the entire growing period. For the Asian part of Russia (Southern Siberia and the southern part of Russian Far East) soil moisture changes within the upper 0-10 and 0-20 cm have no systematic component too. Changes in soil moisture within the thicker layers (the upper 50 cm and the upper 1 m) are currently under scrutiny and results of their analysis will be presented at the Session.

  4. Sensitivity of soil organic matter in anthropogenically disturbed organic soils

    NASA Astrophysics Data System (ADS)

    Säurich, Annelie; Tiemeyer, Bärbel; Bechtold, Michel; Don, Axel; Freibauer, Annette

    2016-04-01

    Drained peatlands are hotspots of carbon dioxide (CO2) emissions from agriculture. However, the variability of CO2 emissions increases with disturbance, and little is known on the soil properties causing differences between seemingly similar sites. Furthermore the driving factors for carbon cycling are well studied for both genuine peat and mineral soil, but there is a lack of information concerning soils at the boundary between organic and mineral soils. Examples for such soils are both soils naturally relatively high in soil organic matter (SOM) such as Humic Gleysols and former peat soils with a relative low SOM content due to intensive mineralization or mixing with underlying or applied mineral soil. The study aims to identify drivers for the sensitivity of soil organic matter and therefore for respiration rates of anthropogenically disturbed organic soils, especially those near the boundary to mineral soils. Furthermore, we would like to answer the question whether there are any critical thresholds of soil organic carbon (SOC) concentrations beyond which the carbon-specific respiration rates change. The German agricultural soil inventory samples all agricultural soils in Germany in an 8x8 km² grid following standardized protocols. From this data and sample base, we selected 120 different soil samples from more than 80 sites. As reference sites, three anthropogenically undisturbed peatlands were sampled as well. We chose samples from the soil inventory a) 72 g kg-1 SOC and b) representing the whole range of basic soil properties: SOC (72 to 568 g kg-1), total nitrogen (2 to 29 g kg-1), C-N-ratio (10 to 80) bulk density (0.06 to 1.41 g/cm³), pH (2.5 to 7.4), sand (0 to 95 %) and clay (2 to 70 %) content (only determined for samples with less than 190 g kg-1 SOC) as well as the botanical origin of the peat (if determinable). Additionally, iron oxides were determined for all samples. All samples were sieved (2 mm) and incubated at standardized water content and

  5. [Transport behaviors of metal oxide nanomaterials in various soils].

    PubMed

    Fang, Jing; Yu, Bo-Yang

    2013-10-01

    Transport behaviors of nano-CeO2, nano-TiO2 and nano-Al2O3 materials in various soils were investigated by column leaching experiment. The relationship between transportability of nanomaterials and soil properties was analyzed and potential transport distances of nanomaterials in soils were estimated by applying the colloid migration dynamic model. The result shows that both nano-CeO2 and nano-TiO2 have strong mobility in most of tested soils. While nano-Al2O3 is almost completely retained in most of tested soils except acidic soil, in which nano-Al2O3 shows relatively strong transportability. The transport mechanisms of nanomaterials in soils are very complicated. Among electrostatic interaction, soil surface charge heterogeneities, aggregation, straining and ripening, each of them plays an important role in the transport of nanomaterials. The transportability of nano-CeO2 is negatively correlated with soil Zeta potential, while that of nano-TiO2 is negatively correlated with soil clay content, and positively correlated with soil permeability coefficients. The transportability of nano-Al2O3 is negatively correlated with soil pH, and positively correlated with soil permeability coefficients. The estimated maximum transport distances of nano-CeO2, nano-TiO2 and nano-Al2O3 materials in soils were 526,9043 cm, 31-332 cm and <10-5,722 cm, respectively. The estimated potential transport distances of nanomaterials in some soils are far more than the surface soil depth of 30 cm, indicating severe risks to deeper soil layers would potentially occur in these soils. PMID:24364330

  6. Arsenic chemistry and remediation in Hawaiian soils.

    PubMed

    Hue, Nguyen V

    2013-01-01

    Past use of arsenical pesticides has resulted in elevated levels of arsenic (As) in some Hawaiian soils. Total As concentrations of 20-100 mg/kg are not uncommon, and can exceed 900 mg/kg in some lands formerly planted with sugarcane. With high contents of amorphous aluminosilicates and iron oxides in many Hawaii's volcanic ash-derived Andisols, a high proportion (25-30%) of soil As was associated with either these mineral phases or with organic matter. Less than 1% of the total As was water soluble or exchangeable. Furthermore, the soils can sorb As strongly: the addition of 1000 mg/kg as As (+5) resulted in only between 0.03 and 0.30 mg/L As in soil solution. In contrast, soils having more crystalline minerals (e.g., Oxisols) sorb less As and thus often contain less As. Phosphate fertilization increases As bioaccessibility, whereas the addition of Fe(OH)3 decreases it. Brake fern (Pteris vittata L.) can be used to remove some soil As. Concentrations of As in fronds varied on average from 60 mg/kg when grown on a low-As Oxisol to 350 mg/kg when grown on a high-As Andisol. Ratios of leaf As to CaCl2-extractable soil As were 12 and 222 for the Oxisol and Andisol, respectively. PMID:23487989

  7. UNDERSTANDING PRODUCTIVITY VARIATION ON UN-IRRIGATED CLAYPAN SOILS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A high clay-content argillic horizon occurring 10 to 100 cm below the surface restricts soil water movement and reduces nutrient efficiency of claypan soils, which affect soil quality related to production and environmental buffering. The objective of this study was to determine the impacts of long-...

  8. Effect of Cover Crops on Soil Fungal Diversity and Biomass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of various cover crops (sordan, mustard, canola, honeysweet, and fallow) to influence soil fungal biomass and diversity were tested in a potato field in the San Luis Valley, Colorado. Soil samples (0-5 cm depth) were randomly selected from each cover crop plot and soil fungal communitie...

  9. CONSTRUCTION, MONITORING, AND PERFORMANCE OF TWO SOIL LINERS

    EPA Science Inventory

    A prototype soil liner and a field-scale soil liner were constructed to test whether compacted soil barrier systems could be built to meet the standard set by the U.S. Environmental Protection Agency (EPA) for saturated hydraulic conductivity (< 1 x 10'7 cm/s). In situ ponded inf...

  10. A 5-cm dipole for the SSC-DE-1

    SciTech Connect

    Caspi, S.

    1990-04-30

    A 5cm SSC superconducting dipole that develops 6.6 tesla at 5790 A is proposed. The two layer magnet has 12% more transfer function than the present design as a result of using thin collars and close in'' iron. The thin collars provide precise positioning of the coils; they also provide minimum prestress (perhaps 2000 psi) as aid for magnet assembly. A welded skin around the iron provides the final prestress and shapes and the coil geometry. A prestressed aluminum bar placed between the vertically split iron yokes provides precise control of the gap between yokes halves and is designed to allow gap to close tightly during cooldown so that there is no decrease of prestress. In order to reduce the effect of iron saturation on the field multipoles the iron ID has been optimized to an elliptical shape. The coil inner layer is a 30 strand cable with 1.3:1 cu/sc. The outer layer is a 36 strand cable wit 1.8:1 cu/sc. At the operating field of 6.6 tesla the current density in the copper is 666 A/mm{sup 2} and 760 A/mm{sup 2} in the inner and outer layers respectively. The magnet short sample performance is limited by the inner layer. Operating at 4.35 K the maximum current and central field are 6896 A and 7.95 tesla. The calculated operating short sample temperature at 6.6 tesla and 5798 A is 5.17 K (0.82 K temperature margin). The magnet stored energy is 100.0 (KJ/m) at the 5790 A operating current. A mechanically similar 5cm bore two layer dipole for the cable test facility (D-16B-1) has been recently built and tested. The magnet had no collars and the iron was placed directly on the coil OD. The magnet's first quench was at 7 tesla with 6000 A and it reached 7.6 tesla at 6600 A. This paper contains tables and figures associated with the design.

  11. Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey

    NASA Astrophysics Data System (ADS)

    Assad, E. D.; Pinto, H. S.; Martins, S. C.; Groppo, J. D.; Salgado, P. R.; Evangelista, B.; Vasconcellos, E.; Sano, E. E.; Pavão, E.; Luna, R.; Camargo, P. B.; Martinelli, L. A.

    2013-10-01

    In this paper we calculated soil carbon stocks in Brazil studying 17 paired sites where soil stocks were determined in native vegetation, pastures and crop-livestock systems (CPS), and in other regional samplings encompassing more than 100 pasture soils, from 6.58 to 31.53° S, involving three major Brazilian biomes: Cerrado, Atlantic Forest, and the Pampa. The average native vegetation soil carbon stocks at 10, 30 and 60 cm soil depth were equal to approximately 29, 64, and 92 Mg ha-1, respectively. In the paired sites, carbon losses of 7.5 Mg ha-1 and 11.6 Mg ha-1 in CPS systems were observed at 10 cm and 30 cm soil depths, respectively. In pasture soils, carbon losses were similar and equal to 7.5 Mg ha-1 and 11.0 Mg ha-1 at 10 cm and 30 cm soil depths, respectively. Differences at 60 cm soil depth were not significantly different between land uses. The average soil δ13C under native vegetation at 10 and 30 cm depth were equal to -25.4‰ and -24.0‰, increasing to -19.6‰ and -17.7‰ in CPS, and to -18.9‰, and -18.3‰ in pasture soils, respectively; indicating an increasing contribution of C4 carbon in these agrosystems. In the regional survey of pasture soils, the soil carbon stock at 30 cm was equal to approximately 51 Mg ha-1, with an average δ13C value of -19.67‰. Key controllers of soil carbon stock in pasture sites were sand content and mean annual temperature. Collectively, both could explain approximately half of the variance of soil carbon stocks. When pasture soil carbon stocks were compared with the average soil carbon stocks of native vegetation estimated for Brazilian biomes and soil types by Bernoux et al. (2002) there was a carbon gain of 6.7 Mg ha-1, which is equivalent to a carbon gain of 15% compared to the carbon soil stock of the native vegetation. The findings of this study are consistent with differences found between regional comparisons like our pasture sites and plot-level paired study sites in estimating soil carbon stocks

  12. Soil penetrometer

    NASA Technical Reports Server (NTRS)

    Howard, E. A.; Hotz, G. M.; Bryson, R. P. (Inventor)

    1968-01-01

    An auger-type soil penetrometer for burrowing into soil formations is described. The auger, while initially moving along a predetermined path, may deviate from the path when encountering an obstruction in the soil. Alterations and modifications may be made in the structure so that it may be used for other purposes.

  13. 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

  14. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  15. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  16. The effect of soil on cork quality

    NASA Astrophysics Data System (ADS)

    Pestana, Miguel; Gomes, Alberto

    2014-10-01

    The present work aimed to contribute for a better knowledge regarding soil features as cork quality indicators for stoppers. Cork sampling was made in eight Cork oak stands (montados de sobreiro) located in different Plio-Plistocene sedimentary formations of Península de Setúbal and Carbonic shistes from paleozoic periods in Saw Grândola, both in southern Tagus River region The samples used to classify the cork as stopper for wine bottles were obtained in eight cork oak stands located in “Península de Setúbal”, south of the River Tagus, covering soils of different types of sandstones of the Plio-plistocene In each stand, we randomly chose five circular plots with 30 m radius. Five trees with same stripping conditions determined by the dendrometric features: HD (height stipping, PBH (perimeter at breaster height), and percentage canopy cover, trees vegetative condition (defoliation degree) stand features (density), and site conditions (soil type and orientation). In the center of each plot a pit was open to characterize the soil profile and to classify the soil of each plot sampling. Cork quality for stoppers was evaluated according to porosity, pores/per cm 2 and thickness. The soil was characterized according to morphological soil profile features (lithology, soil profound and soil horizons) and chemical soil surface horizon features (organic matter, pH, macro and micronutrients availability). Based on the variables studied and using the numerical taxonomy, we settled relationships between the cork quality and some soil features. The results indicate: (1) high correlation between the cork caliber and boron, caption exchange capacity, total nitrogen, exchange acidity and exchangeable magnesium, potassium, calcium and sodium in soils of theirs cork oaks; (2) the cork porosity is correlated with the number of pores/cm2 and magnesium; (3) the other soil features have a lower correlation with the caliber, porosity and the number of pores per cm2.

  17. Microbiological study of the Murchison CM2 meteorite

    NASA Astrophysics Data System (ADS)

    Pikuta, Elena V.; Hoover, Richard B.

    2012-10-01

    In 1864, Louis Pasteur attempted to cultivate living microorganisms from pristine samples of the Orgueil CI1 carbonaceous meteorite. His results were negative and never published, but recorded it in his laboratory notebooks. At that time, only aerobic liquid or agar-based organic reach media were used, as his research on anaerobes had just started. In our laboratory the Murchison CM2 carbonaceous meteorite was selected to expand on these studies for microbiological study by cultivation on anaerobic mineral media. Since the surface could have been more easily contaminated, interior fragments of a sample of the Murchison meteorite were extracted and crushed under sterile conditions. The resulting powder was then mixed in anoxic medium and injected into Hungate tubes containing anaerobic media with various growth substrates at different pH and salinity and incubated at different temperatures. The goal of the experiments was to determine if living cells would grow from the material of freshly fractured interior fragments of the stone. If any growth occurred, work could then be carried out to assess the nature of the environmental contamination by observations of the culture growth (rates of speed and biodiversity); live/dead fluorescent staining to determine contamination level and DNA analysis to establish the microbial species present. In this paper we report the results of that study.

  18. Piezo-Operated Shutter Mechanism Moves 1.5 cm

    NASA Technical Reports Server (NTRS)

    Glaser, Robert; Bamford, Robert

    2005-01-01

    The figure shows parts of a shutter mechanism designed to satisfy a number of requirements specific to its original intended application as a component of an atomic clock to be flown in outer space. The mechanism may also be suitable for use in laboratory and industrial vacuum systems on Earth for which there are similar requirements. The requirements include the following: a) To alternately close, then open, a 1.5-cm-diameter optical aperture twice per second, with a stroke time of no more than 15 ms, during a total operational lifetime of at least a year; b) To attenuate light by a factor of at least 1012 when in the closed position; c) To generate little or no magnetic field; d) To be capable of withstanding bakeout at a temperature of 200 C to minimize outgassing during subsequent operation in an ultrahigh vacuum; and e) To fit within a diameter of 12 in. (=305 mm) a size limit dictated by the size of an associated magnetic shield. The light-attenuation requirement is satisfied by use of overlapping shutter blades. The closure of the aperture involves, among other things, insertion of a single shutter blade between a pair of shutter blades. The requirement to minimize the magnetic field is satisfied by use of piezoelectric actuators. Because piezoelectric actuators cannot withstand bakeout, they must be mounted outside the vacuum chamber, and, hence, motion must be transmitted from the actuators to the shutter levers via a vacuum-chamber-wall diaphragm.

  19. CM and DM in an ISO R and D Environment

    NASA Technical Reports Server (NTRS)

    Crowley, Sandra L.

    2000-01-01

    ISO 9000 - a common buzz word in industry is making inroads to government agencies. The National Aeronautics and Space Agency (NASA) achieved ISO 9001 certification at each of its nine (9) Centers and Headquarters in 1998-1999. NASA Glenn Research Center (GRC) was recommended for certification in September 1999. Since then, each of the Centers has been going through the semi-annual surveillance audits. Growing out of the manufacturing industry, successful application of the international quality standard to a research and development (R&D) environment has had its challenges. This paper will address how GRC applied Configuration Management (CM) and Data (or Document) Management (DM) to meet challenges to achieve ISO certification. One of the first challenges was to fit the ISO 9001-1994 elements to the GRC environment. Some of the elements fit well-Management Responsibility (4.1), Internal Audits (4.17), Document and Data Control (4.5). Other elements were not suited or applied easily to the R&D environment-Servicing (4.19), Statistical Techniques (4.20). Since GRC "builds" only one or two items at a time, these elements were considered not applicable to the environment.

  20. The 15 cm mercury ion thruster research 1975

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1975-01-01

    Doubly charged ion current measurements in the beam of a SERT II thruster are shown to introduce corrections which bring its calculated thrust into close agreement with that measured during flight testing. A theoretical model of doubly charged ion production and loss in mercury electron bombardment thrusters is discussed and is shown to yield doubly-to-singly charged ion density ratios that agree with experimental measurements obtained on a 15 cm diameter thruster over a range of operating conditions. Single cusp magnetic field thruster operation is discussed and measured ion beam profiles, performance data, doubly charged ion densities, and discharge plasma characteristics are presented for a range of operating conditions and thruster geometries. Variations in the characteristics of this thruster are compared to those observed in the divergent field thruster and the cusped field thruster is shown to yield flatter ion beam profiles at about the same discharge power and propellant utilization operating point. An ion optics test program is described and the measured effects of grid system dimensions on ion beamlet half angle and diameter are examined. The effectiveness of hollow cathode startup using a thermionically emitting filament within the cathode is examined over a range of mercury flow rates and compared to results obtained with a high voltage tickler startup technique. Results of cathode plasma property measurement tests conducted within the cathode are presented.

  1. Performance and Vibration of 30 cm Pyrolytic Ion Thruster Optics

    NASA Technical Reports Server (NTRS)

    Haag, Thomas; Soulas, George C.

    2004-01-01

    Carbon has a sputter erosion rate about an order of magnitude less than that of molybdenum, over the voltages typically used in ion thruster applications. To explore its design potential, 30 cm pyrolytic carbon ion thruster optics have been fabricated geometrically similar to the molybdenum ion optics used on NSTAR. They were then installed on an NSTAR Engineering Model thruster, and experimentally evaluated over much of the original operating envelope. Ion beam currents ranged from 0.51 to 1.76 Angstroms, at total voltages up to 1280 V. The perveance, electron back-streaming limit, and screen-grid transparency were plotted for these operating points, and compared with previous data obtained with molybdenum. While thruster performance with pyrolytic carbon was quite similar to that with molybdenum, behavior variations can reasonably be explained by slight geometric differences. Following all performance measurements, the pyrolytic carbon ion optics assembly was subjected to an abbreviated vibration test. The thruster endured 9.2 g(sub rms) of random vibration along the thrust axis, similar to DS 1 acceptance levels. Despite significant grid clashing, there was no observable damage to the ion optics assembly.

  2. Ion thruster system (8-cm) cyclic endurance test

    NASA Technical Reports Server (NTRS)

    Dulgeroff, C. R.; Beattie, J. R.; Poeschel, R. L.; Hyman, J., Jr.

    1984-01-01

    This report describes the qualification test of an Engineering-Model 5-mN-thrust 8-cm-diameter mercury ion thruster which is representative of the Ion Auxiliary Propulsion System (IAPS) thrusters. Two of these thrusters are scheduled for future flight test. The cyclic endurance test described herein was a ground-based test performed in a vacuum facility with a liquid-nitrogen-cooled cryo-surface and a frozen mercury target. The Power Electronics Unit, Beam Shield, Gimal, and Propellant Tank that were used with the thruster in the endurance test are also similar to those of the IAPS. The IAPS thruster that will undergo the longest beam-on-time during the actual space test will be subjected to 7,055 hours of beam-on-time and 2,557 cycles during the flight test. The endurance test was successfully concluded when the mercury in the IAPS Propellant Tank was consumed. At that time, 8,471 hours of beam-on-time and 599 cycles had been accumulated. Subsequent post-test-evaluation operations were performed (without breaking vacuum) which extended the test values to 652 cycles and 9,489 hours of beam-on-time. The Power Electronic Unit (PEU) and thruster were in the same vacuum chamber throughout the test. The PEU accumulated 10,268 hr of test time with high voltage applied to the operating thruster or dummy load.

  3. A 21-cm Neutral Hydrogen Study of Arp 213

    NASA Astrophysics Data System (ADS)

    Wells, S. J.; Simpson, C. E.

    2002-12-01

    We present 21-cm VLA observations of the Sab galaxy Arp 213. An extended HI disk (approx. 2.3 RHolm) was detected, with a bifurcated or extra arm on the west featuring a large HI knot. Based on the kinematics, this knot does not appear to be a dwarf or small companion, but a local enhancement in the arm. Although no unusual kinematics appear in the region of the odd radial dust lanes that attracted Arp's attention to this galaxy, there is a very low level HI cloud just north of the galaxy at the same position angle. The total HI mass for the galaxy was measured to be 2.9 x 109 Msun. Arp 213 has a high rotational velocity (300 km s-1), and a flat rotation curve that rises in the outermost regions. The calculated dynamical mass for the system is quite high at 4.4 x 1011 Msun. The rotation curve and dynamic mass indicate the presence of a large dark matter halo. Further optical data is needed to confirm its mass. This work was supported by NSF grant AST-0097616 and the SARA Consortium REU program.

  4. Parallel Preconditioning for CFD Problems on the CM-5

    NASA Technical Reports Server (NTRS)

    Simon, Horst D.; Kremenetsky, Mark D.; Richardson, John; Lasinski, T. A. (Technical Monitor)

    1994-01-01

    Up to today, preconditioning methods on massively parallel systems have faced a major difficulty. The most successful preconditioning methods in terms of accelerating the convergence of the iterative solver such as incomplete LU factorizations are notoriously difficult to implement on parallel machines for two reasons: (1) the actual computation of the preconditioner is not very floating-point intensive, but requires a large amount of unstructured communication, and (2) the application of the preconditioning matrix in the iteration phase (i.e. triangular solves) are difficult to parallelize because of the recursive nature of the computation. Here we present a new approach to preconditioning for very large, sparse, unsymmetric, linear systems, which avoids both difficulties. We explicitly compute an approximate inverse to our original matrix. This new preconditioning matrix can be applied most efficiently for iterative methods on massively parallel machines, since the preconditioning phase involves only a matrix-vector multiplication, with possibly a dense matrix. Furthermore the actual computation of the preconditioning matrix has natural parallelism. For a problem of size n, the preconditioning matrix can be computed by solving n independent small least squares problems. The algorithm and its implementation on the Connection Machine CM-5 are discussed in detail and supported by extensive timings obtained from real problem data.

  5. Enhanced Detectability of Pre-reionization 21 cm Structure

    NASA Astrophysics Data System (ADS)

    Alvarez, Marcelo A.; Pen, Ue-Li; Chang, Tzu-Ching

    2010-11-01

    Before the universe was reionized, it was likely that the spin temperature of intergalactic hydrogen was decoupled from the cosmic microwave background (CMB) by UV radiation from the first stars through the Wouthuysen-Field effect. If the intergalactic medium (IGM) had not yet been heated above the CMB temperature by that time, then the gas would appear in absorption relative to the CMB. Large, rare sources of X-rays could inject sufficient heat into the neutral IGM, so that δTb >0 at comoving distances of tens to hundreds of Mpc, resulting in large 21 cm fluctuations with δTb ~= 250 mK on arcminute to degree angular scales, an order of magnitude larger in amplitude than that caused by ionized bubbles during reionization, δTb ~= 25 mK. This signal could therefore be easier to detect and probe higher redshifts than that due to patchy reionization. For the case in which the first objects to heat the IGM are QSOs hosting 107 M sun black holes with an abundance exceeding ~1 Gpc-3 at z ~ 15, observations with either the Arecibo Observatory or the Five Hundred Meter Aperture Spherical Telescope could detect and image their fluctuations at greater than 5σ significance in about a month of dedicated survey time. Additionally, existing facilities such as MWA and LOFAR could detect the statistical fluctuations arising from a population of 105 M sun black holes with an abundance of ~104 Gpc-3 at z ~= 10-12.

  6. [Microelement contents of litter, soil fauna and soil in Pinus koraiensis and broad-leaved mixed forest].

    PubMed

    Yin, Xiu-qin; Li, Jin-xia; Dong, Wei-hua

    2007-02-01

    The analysis on the Mn, Zn and Cu contents of litter, soil fauna and soil in Pinus korazenszis and broad-leaved mixed forest in Liangshui Natural Reserve of Xiaoxing' an Mountains showed that the test microelement contents in the litter, soil fauna and soil all followed the sequence of Mn > Zn > Cu, but varied with these environmental components, being in the sequence of soil > litter > soil fauna for Mn, soil fauna > litter and soil for Zn, and soil fauna > soil > litter for Cu. The change range of test microelement contents in litter was larger in broad-leaved forest than in coniferous forest. Different soil fauna differed in their microelement-enrichment capability, e. g. , earthworm, centipede, diplopod had the highest content of Mn, Zn and Cu, respectively. The contents of test microelements in soil fauna had significant correlations with their environmental background values, litter decomposition rate, food habit of soil fauna, and its absorbing selectivity and enrichment to microelements. The microelements contained in 5-20 cm soil layer were more than those in 0-5 cm soil layer, and their dynamics differed in various soil layers. PMID:17450727

  7. Quantifying the pluri-centennial soil organic carbon pool using Rock-Eval pyrolysis

    NASA Astrophysics Data System (ADS)

    Cécillon, Lauric; Baudin, François; Chenu, Claire; Christensen, Bent T.; Houot, Sabine; Kätterer, Thomas; Lutfalla, Suzanne; Macdonald, Andy; van Oort, Folkert; Plante, Alain F.; Savignac, Florence; Soucémarianadin, Laure; Barré, Pierre

    2016-04-01

    amount (5 to 95%) of CH, CO and CO2 gas had evolved during the RE6 pyrolysis and oxidation steps. These RE6 predictors were used in a random forest (RF) multivariate regression model to predict the proportion of the pluri-centennial SOC pool. Our RE6-RF model showed an excellent predictive performance: out-of-bag R²=0.93, out-of-bag error=6% of total SOC (n=86); validation R²=0.96, prediction error=5% of total SOC (n=20). We then applied our RE6-RF model on 50 cropland and forest topsoils (0-30cm) with contrasting geo-pedology (region of Grignon, FR). Despite its wide heterogeneity, this new sample set was within the prediction range of our RE6-RF model. The RE6-RF predicted proportion of the pluri-centennial SOC pool was consistently higher in cropland than in forest soils (p<0.001), while its concentration (gC.kg-1soil) was not affected by land-use. Conversely, the concentration of the pluri-centennial SOC pool was markedly dependent on soil type (p=0.01) and parent material (p=0.001), indicating a clear geochemical control on the pluri-centennial soil organic carbon reservoir. Our study positions RE6 pyrolysis as a meaningful tool to quantify the pluri-centennial SOC pool, with the ability of detecting its landscape-scale heterogeneities.

  8. Dynamics of Soil Heat Flux in Lowland Area: Estimating the Soil Thermal Conductivy

    NASA Astrophysics Data System (ADS)

    Zimmer, T.; Silveira, M. V.; Roberti, D. R.

    2013-05-01

    In this work, it is shown soil thermal conductivity estimates in a flooded irrigated rice culture located at the Paraíso do Sul city for two distinct periods. The thermal conductivity is higher when the heat storage is higher and the soil surface temperature is lower. The soil thermal conductivity is also dependant on the soil texture, porosity and moisture. Therefore, it varies from soil to soil and in the same soil, depending on its soil moisture. For approximately 80% of its growing season, lowland flooded irrigated rice ecosystems stay under a 5 - 10 cm water layer. It affects the partitioning of the energy and water balance components. Furthermore this planting technique differs substantially from any other upland non-irrigated or irrigated crop ecosystems where the majority of observational studies have been conducted. In the present work, the dynamic of soil heat flux (G) is analyzed and the soil thermal conductivity (Ks) is estimated using experimental data form soil heat flux and soil temperature in a rice paddy farm in a subtropical location in Southern Brazil. In this region, rice grows once a year at river lowlands and wetlands while the ground is kept bare during the remaining of the year. The soil type is Planossolo Hidromórfico Distrófico, characterized as a mix between sandy and clay soil. The soil heat flux (G) was experimentally estimated with the sensor Hukseflux (HFP01SC-L) at 7 cm bellow the soil surface. The soil temperature at 5 cm and 10 cm was experimentally estimated using the sensor STP01. The experimental soil heat flux was compared with estimated soil heat flux by two forms: (1) using a know Ks from literature for this type of soil in saturated conditions (Ks=1.58); (2) using Ks estimated using the inversion of the equation Qg=-ks* ((T10-T5)/ (Z2-Z1)), where T10 and T5 are the temperature in 10 and 5 cm above the soil and Z2-Z1 is the difference between the positions in temperature measurement. The study period for estimating the Ks

  9. A multivariate analysis of the accumulation and fractionation of major and trace elements in agricultural soils in Hidalgo State, Mexico irrigated with raw wastewater.

    PubMed

    Lucho-Constantino, Carlos A; Alvarez-Suárez, Miriam; Beltrán-Hernández, Rosa I; Prieto-García, Francisco; Poggi-Varaldo, Héctor M

    2005-04-01

    We evaluated the accumulation and distribution of major and trace elements in agricultural soils of District 03 (DR03) in the State of Hidalgo, Mexico, irrigated with raw wastewaters for an average of 20 years. Samples of topsoils (0-30 cm depth) were extracted using a modified Tessier method. Total concentrations of the species tested were in the ranges of 675-1176 mg K kg(-1), 277.9-1001 mg Na kg(-1), 6,708-81,854 mg Ca kg(-1), 23,800-106,974 mg Mg kg(-1), 9.2-123.8 mg B kg(-1), 0.6-1.9 mg Cd kg(-1), 11.6-27.4 mg Cr kg(-1), 3.9-47.0 mg Pb kg(-1). Concentrations of As and Hg were very low. Concentrations of total Cd, Cr and Pb were generally below the maximum permissible levels set by the regulations of the European Union except for cadmium, which was in the middle of the maximum European range allowed for two soils. Regarding lead, one soil (S5) could reach the maximum permissible level of the EU in 6 more years of continued irrigation. On the other hand, contents of Pb in the most mobile fractions ("e" in this work) were significant (range: 3-28%). This distribution translated into concentrations of soluble plus exchangeable lead of approximately 2 mg Pb kg(-1) in three of six soils, significantly higher than the Swiss tolerance limit of 1.0 mg Pb kg(-1) for mobile fractions of lead in soils. Multivariate analysis of the data (Pearson correlation and principal component analysis) quantitatively confirmed that: (i) there is a strong covariance between boron contents and several variables representing the salinity of soils (electrolytic conductivity, a variety of alkaline and alkaline-earth total and fraction concentrations). It appears that there is a problem with high boron content in soils, although the salinity is high only for one of the soils (S3); (ii) a significant correlation among irrigation time, lead content (total, fraction easily exchangeable and bound to organic matter and sulfides) and organic carbon in soils was found; (iii) another association

  10. Spatial Resolution Effects of Remote Sensing Informed Soil Nutrient Models Based on Landsat 8, RapidEye, WorldView-2 and GeoEye-1 Images

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Grunwald, S.; Smith, S. E.; Abd-Elrahman, A.; Clingensmith, C. M.; Wani, S.

    2015-12-01

    Soil nutrient storage is essential and important to maintain food security and soil security in smallholder farm settings. The objective of this research was to analyze the spatial resolution effects of different remote sensing images on soil prediction models in Kothapally, India. We utilized Bayesian kriging (BK) to characterize the spatial pattern of total nitrogen (TN) and exchangeable potassium (Kex) in the topsoil (0-15 cm) at different spatial resolutions by incorporating spectral indices from Landsat 8 (30m), RapidEye (5m) and WorldView-2/GeoEye-1 images (2m). The band ratio of red to green, red to blue and green to blue, Crust Index and Atmospherically Resistant Vegetation Index from multiple images generally had high linear correlations with TN and Kex. The BK model of TN based on WorldView-2 and GeoEye-1 attained the highest model fit (R2=0.41) and lowest prediction error (RMSE=171.35 mg kg-1) compared with the BK models of TN based on Landsat 8 (R2=0.30; RMSE=182.26 mg kg-1) and RapidEye (R2=0.28; RMSE=183.52 mg kg-1). The BK model of Kex based on Landsat 8 had the highest model fit (R2=0.55) and the second lowest prediction error (RMSE=79.57 mg kg-1) compared with the BK models of Kex based on WorldView-2 and GeoEye-1 (R2=0.52; RMSE=79.42 mg kg-1) and RapidEye (R2=0.47; RMSE=83.91 mg kg-1). The lowest prediction fit and highest prediction error of soil TN and Kex models based on RapidEye suggest that the effect of fine spatial remote sensing spectral data inputs do not always lead to an increase of model fit. Soil maps based on WorldView-2 and GeoEye-1 have significant advantages in characterizing the variation of soil TN and Kex spatial pattern in smallholder farm settings compared with coarser maps. This research suggests that Digital Soil Mapping utilizing remote sensing spectral data from WorldView-2 and GeoEye-1 has high potential to be widely applied in smallholder farm settings and help smallholder farmers manage their soils and attain soil

  11. Formation of asteroids from mm-cm sized grains

    NASA Astrophysics Data System (ADS)

    Carrera, D.; Johansen, A.; Davies, M. B.

    2014-03-01

    Context. Asteroids and comets are intricately connected to life in the universe. Asteroids are the building blocks of terrestrial planets; water-rich asteroids and comets are likely to be the primary source of water for Earth's oceans and other volatiles (Morbidelli et al. 2000; Hartogh et al. 2011); and they may play role in mass extinctions. Yet, the formation of these objects is poorly understood. There is mounting evidence that the traditional picture of the formation of asteroids must be revised. The size distribution of asteroids is hard to reconcile with a traditional bottomup formation scenario. Instead, asteroids may form top-down, with large 100 - 1000 km sized objects forming first by the gravitational collapse of dense clumps of small particles. Experiments and simulations suggest that dust grains cannot grow to sizes larger than mm-cm in protoplanetary disks (Zsom et al. 2010). Also, primitive meteorites from the asteroid belt contain a large mass fraction in chondrules of sizes from 0.1 mm to a few mm. Hence, it is desirable to find a model for asteroid formation from mm-sized particles. Aims. In this work, we model the dynamics of mm-cm sized grains in dust-enriched inner regions of protoplanetary disks. We model the dust-gas interaction to determine whether dust grains of this size can form dense, self-gravitating clouds that can collapse to form asteroids. Methods. We perform shearing box simulations of the inner disk using the Pencil Code (Brandenburg & Dobler 2002). The simulations start with a Solar-type solids-to-gas ratio of 0.01 and we gradually increase the particle concentration. In a real protoplanetary disk, solid particles are expected to migrate from the outer regions and concentrate in the inner disk. Results. Our simulations show that mm-sized particles can form very dense clumps, driven by a run-away convergence in the radial-drift flow of these particles - this dynamic is known as the streaming instability (Youdin & Goodman 2005

  12. A 1.3 cm line survey toward Orion KL

    NASA Astrophysics Data System (ADS)

    Gong, Y.; Henkel, C.; Thorwirth, S.; Spezzano, S.; Menten, K. M.; Walmsley, C. M.; Wyrowski, F.; Mao, R. Q.; Klein, B.

    2015-09-01

    Context. The nearby Orion Kleinmann-Low nebula is one of the most prolific sources of molecular line emission. It has served as a benchmark for spectral line searches throughout the (sub)millimeter regime. Aims: The main goal is to systematically study the spectral characteristics of Orion KL in the λ ~ 1.3 cm band. Methods: We carried out a spectral line survey with the Effelsberg-100 m telescope toward Orion KL. It covers the frequency range between 17.9 GHz and 26.2 GHz, i.e., the radio "K band". We also examined ALMA maps to address the spatial origin of molecules detected by our 1.3 cm line survey. Results: In Orion KL, we find 261 spectral lines, yielding an average line density of about 32 spectral features per GHz above 3σ (a typical value of 3σ is 15 mJy). The identified lines include 164 radio recombination lines (RRLs) and 97 molecular lines. The RRLs, from hydrogen, helium, and carbon, stem from the ionized material of the Orion Nebula, part of which is covered by our beam. The molecular lines are assigned to 13 different molecular species including rare isotopologues. A total of 23 molecular transitions from species known to exist in Orion KL are detected for the first time in the interstellar medium. Non-metastable (J>K) 15NH3 transitions are detected in Orion KL for the first time. Based on the velocity information of detected lines and the ALMA images, the spatial origins of molecular emission are constrained and discussed. A narrow feature is found in SO2 (81,7 - 72,6), but not in other SO2 transitions, possibly suggesting the presence of a maser line. Column densities and fractional abundances relative to H2 are estimated for 12 molecules with local thermodynamic equilibrium (LTE) methods. Rotational diagrams of non-metastable 14NH3 transitions with J = K + 1 to J = K + 4 yield different results; metastable (J = K) 15NH3 is found to have a higher excitation temperature than non-metastable 15NH3, also indicating that they may trace different

  13. Draft Genome Sequences of Acinetobacter parvus CM11, Acinetobacter radioresistens CM38, and Stenotrophomonas maltophilia BR12, Isolated from Murine Proximal Colonic Tissue

    PubMed Central

    Saffarian, Azadeh; Mulet, Céline; Naito, Tomoaki; Bouchier, Christiane; Tichit, Magali; Ma, Laurence; Grompone, Gianfranco

    2015-01-01

    Here, we report three genome sequences of bacteria isolated from murine proximal colonic tissue and identified as Acinetobacter parvus CM11, Acinetobacter radioresistens CM38, and Stenotrophomonas maltophilia BR12. PMID:26472823

  14. Draft Genome Sequences of Acinetobacter parvus CM11, Acinetobacter radioresistens CM38, and Stenotrophomonas maltophilia BR12, Isolated from Murine Proximal Colonic Tissue.

    PubMed

    Saffarian, Azadeh; Mulet, Céline; Naito, Tomoaki; Bouchier, Christiane; Tichit, Magali; Ma, Laurence; Grompone, Gianfranco; Sansonetti, Philippe J; Pédron, Thierry

    2015-01-01

    Here, we report three genome sequences of bacteria isolated from murine proximal colonic tissue and identified as Acinetobacter parvus CM11, Acinetobacter radioresistens CM38, and Stenotrophomonas maltophilia BR12. PMID:26472823

  15. soil organic matter fractionation

    NASA Astrophysics Data System (ADS)

    Osat, Maryam; Heidari, Ahmad

    2010-05-01

    Carbon is essential for plant growth, due to its effects on other soil properties like aggregation. Knowledge of dynamics of organic matter in different locations in the soil matrix can provide valuable information which affects carbon sequestration and soil the other soil properties. Extraction of soil organic matter (SOM) fractions has been a long standing approach to elucidating the roles of soil organic matter in soil processes. Several kind fractionation methods are used and all provide information on soil organic matter function. Physical fractionation capture the effects on SOM dynamics of the spatial arrangement of primary and secondary organomineral particles in soil while chemical fractionation can not consider the spatial arrangement but their organic fractions are suitable for advanced chemical characterization. Three method of physical separation of soil have been used, sieving, sedimentation and densitometry. The distribution of organic matter within physical fractions of the soil can be assessed by sieving. Sieving separates soil particles based strictly on size. The study area is located on north central Iran, between 35° 41'- 36° 01' N and 50° 42'- 51° 14' E. Mean annual precipitation about 243.8 mm and mean annual air temperature is about 14.95 °C. The soil moisture and temperature regime vary between aridic-thermic in lower altitudes to xeric-mesic in upper altitudes. More than 36 surface soil samples (0-20 cm) were collected according to land-use map units. After preliminary analyzing of samples 10 samples were selected for further analyses in five size fractions and three different time intervals in September, January and April 2008. Fractionation carried out by dry sieving in five classes, 1-2 mm, 0.5-1 mm, 270 μm-0.5mm, 53-270 μm and <53 μm. Organic matter and C/N ratio were determined for all fractions at different time intervals. Chemical fractionation of organic matter also carried out according to Tan (2003), also Mineralogical

  16. Pyromineralization of soil phosphorus in savanna ecosystems

    NASA Astrophysics Data System (ADS)

    Hartshorn, A.; Coetsee, C.; Chadwick, O.

    2007-12-01

    The weathering of rock supplies phosphorus (P) to ecosystems. Phosphorus limitation of ecosystems can be severe in thicker or older soils, where soil production rates from rock and therefore release of P is slower than in thinner or younger soils. Limitation may be especially pronounced in drier ecosystems that are experiencing increasing N deposition. Our savanna field sites in Kruger National Park, South Africa meet all three of these criteria: soil residence times average 250 ky, the climate is semiarid, and N inputs average 20 kg ha-1 y-1. Not all soil P is plant-available, and because our field sites experience occasional fires, our objectives were to quantify the importance of pyromineralization of soil P, the transfer by fire of soil P from recalcitrant to labile (HCO3- extractable) pools. We quantified these soil P pools using a modified Hedley scheme (an array of chemical extractants). Three sets of soils were fractionated: 1. soils from 10 profiles along an intensively studied hillslope, bracketing a pronounced structural and functional ecotone; 2. surface soils from these 10 profiles after a simulated burn; and 3. surface soils from the Shabeni Experimental Plots, where 4 fire treatments have been maintained for decades: no fire, annual fire in the dry season, triennial fire in the dry season, and triennial fire in the wet season. Total P for hillslope soils ranged from 45 to 135 g m-2 (to 50 cm depth) and from 8 to 15 g m-2 (to 5 cm depth). Total soil P was lowest in midslope soils, where upslope sandy soils dominated by broad-leafed vegetation shift abruptly to downslope clayey soils with fine-leafed vegetation. Simulated fire for the hillslope soils reduced total P slightly, but boosted labile P by 1.7 g m-2 (to 5 cm), representing 17% of total P in the surface 5 cm. This pyromineralization effect was not uniform across the hillslope: downslope soils gained about 50% more labile P than midslope soils with simulated burning. With a fire return interval

  17. Impact of alpine meadow degradation on soil hydraulic properties over the Qinghai-Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zeng, Chen; Zhang, Fan

    2015-04-01

    Alpine meadow is one of widespread vegetation types of the Qinghai-Tibetan Plateau. It is undergoing degradation under the background of global climate change, human activities and overgrazing. Soil moisture is important to alpine meadow ecology for its water and energy transfer processes, therefore soil hydraulic properties become key parameters for local eco-hydrological processes studies. However, little research focus on the changes and it's mechanisms of soil hydraulic properties during the degradation processes. In this study, soil basic and hydraulic properties at 0-10 cm and 40-50 cm soil layer depths under different degraded alpine meadow were analyzed. Pearson correlations were adopted to study the relationships among the investigated factors and principal component analysis was performed to identify the dominant factor. Results show that with increasing degree of degradation, soil sand content increased while soil saturated hydraulic conductivity (Ks) as well as soil clay content, soil porosity decreased in the 0-10 cm soil layers, and organic matter and root gravimetric density decreased in both the 0-10 cm and 40-50 cm soil layers. For soil unsaturated hydraulic conductivity, it reduced more slowly with decreasing pressure head under degraded conditions than non-degraded conditions. However, soil moisture showed no significant changes with increasing degradation. Soil Ks was significantly correlated (P = 0.01) with bulk density, soil porosity, soil organic matter and root gravimetric density. Among these, soil porosity is the dominant factor explaining about 90% of the variability in total infiltration flow. Under non-degraded conditions, the infiltration flow principally depended on the presence of macropores. With increasing degree of degradation, soil macropores quickly changed to mesopores or micropores. The proportion of total infiltration flow through macropores and mesopores significantly decreased with the most substantial decrease observed for

  18. Radar reflectivity of bare and vegetation-covered soil

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dobson, M. C.; Bradley, G. A.

    1981-01-01

    Radar sensitivity to soil moisture content has been investigated experimentally for bare and vegetation-covered soil using detailed spectral measurements obtained by a truck-mounted radar spectrometer in the 1-8 GHz band and by airborne scatterometer observations at 1.6, 4.75, and 13.3 GHz. It is shown that radar can provide quantitative information on the soil moisture content of both bare and vegetation-covered soil. The observed soil moisture is in the form of the soil matric potential or a related quantity such as the percent of field capacity. The depth of the monitored layer varies from 1 cm for very wet soil to about 15 cm for very dry soil.

  19. [Characteristics of soil pH and exchangeable acidity in red soil profile under different vegetation types].

    PubMed

    Ji, Gang; Xu, Ming-gang; Wen, Shi-lin; Wang, Bo-ren; Zhang, Lu; Liu, Li-sheng

    2015-09-01

    The characteristics of soil pH and exchangeable acidity in soil profile under different vegetation types were studied in hilly red soil regions of southern Hunan Province, China. The soil samples from red soil profiles within 0-100 cm depth at fertilized plots and unfertilized plots were collected and analyzed to understand the profile distribution of soil pH and exchangeable acidity. The results showed that, pH in 0-60 cm soil from the fertilized plots decreased as the following sequence: citrus orchard > Arachis hypogaea field > tea garden. As for exchangeable acidity content, the sequence was A. hypogaea field ≤ citrus orchard < tea garden. After tea tree and A. hypogaea were planted for long time, acidification occurred in surface soil (0-40 cm), compared with the deep soil (60-100 cm), and soil pH decreased by 0.55 and 0.17 respectively, but such changes did not occur in citrus orchard. Soil pH in 0-40 cm soil from the natural recovery vegetation unfertilized plots decreased as the following sequence: Imperata cylindrica land > Castanea mollissima garden > Pinus elliottii forest ≥ Loropetalum chinensis forest. As for exchangeable acidity content, the sequence was L cylindrica land < C. mollissima garden < L. chinensis forest ≤ P. elliottii forest. Soil pH in surface soil (0-20 cm) from natural forest plots, secondary forest and Camellia oleifera forest were significantly lower than that from P. massoniana forest, decreased by 0.34 and 0.20 respectively. For exchangeable acidity content in 0-20 cm soil from natural forest plot, P. massoniana forest and secondary forest were significantly lower than C. oleifera forest. Compared with bare land, surface soil acidification in unfertilized plots except I. cylindrica land had been accelerated, and the natural secondary forest was the most serious among them, with surface soil pH decreasing by 0.52. However, the pH increased in deep soils from unfertilized plots except natural secondary forest, and I. cylindrica

  20. Key soil functional properties affected by soil organic matter - evidence from published literature

    NASA Astrophysics Data System (ADS)

    Murphy, Brian

    2015-07-01

    The effect of varying the amount of soil organic matter on a range of individual soil properties was investigated using a literature search of published information largely from Australia, but also included relevant information from overseas. Based on published pedotransfer functions, soil organic matter was shown to increase plant available water by 2 to 3 mm per 10 cm for each 1% increase in soil organic carbon, with the largest increases being associated with sandy soils. Aggregate stability increased with increasing soil organic carbon, with aggregate stability decreasing rapidly when soil organic carbon fell below 1.2 to 1.5 5%. Soil compactibility, friability and soil erodibility were favourably improved by increasing the levels of soil organic carbon. Nutrient cycling was a major function of soil organic matter. Substantial amounts of N, P and S become available to plants when the soil organic matter is mineralised. Soil organic matter also provides a food source for the microorganisms involved in the nutrient cycling of N, P, S and K. In soils with lower clay contents, and less active clays such as kaolinites, soil organic matter can supply a significant amount of the cation exchange capacity and buffering capacity against acidification. Soil organic matter can have a cation exchange capacity of 172 to 297 cmol(+)/kg. As the cation exchange capacity of soil organic matter varies with pH, the effectiveness of soil organic matter to contribute to cation exchange capacity below pH 5.5 is often minimal. Overall soil organic matter has the potential to affect a range of functional soil properties.

  1. Integrating soil conservation practices and glyphosate-resistant crops: impacts on soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    From an environmental perspective, conservation management (CM) practices such as reduced tillage help improve soil conditions. Literature concerning effects of CM on the environment is building, and many of those studies include glyphosate resistant crops (GRC) or glyphosate as a management compon...

  2. ICD-9-CM and ICD-10-CM mapping of the AAST Emergency General Surgery disease severity grading systems: Conceptual approach, limitations, and recommendations for the future.

    PubMed

    Utter, Garth H; Miller, Preston R; Mowery, Nathan T; Tominaga, Gail T; Gunter, Oliver; Osler, Turner M; Ciesla, David J; Agarwal, Suresh K; Inaba, Kenji; Aboutanos, Michel B; Brown, Carlos V R; Ross, Steven E; Crandall, Marie L; Shafi, Shahid

    2015-05-01

    The American Association for the Surgery of Trauma (AAST) recently established a grading system for uniform reporting of anatomic severity of several emergency general surgery (EGS) diseases. There are five grades of severity for each disease, ranging from I (lowest severity) to V (highest severity). However, the grading process requires manual chart review. We sought to evaluate whether International Classification of Diseases, 9th and 10th Revisions, Clinical Modification (ICD-9-CM, ICD-10-CM) codes might allow estimation of AAST grades for EGS diseases. The Patient Assessment and Outcomes Committee of the AAST reviewed all available ICD-9-CM and ICD-10-CM diagnosis codes relevant to 16 EGS diseases with available AAST grades. We then matched grades for each EGS disease with one or more ICD codes. We used the Official Coding Guidelines for ICD-9-CM and ICD-10-CM and the American Hospital Association's "Coding Clinic for ICD-9-CM" for coding guidance. The ICD codes did not allow for matching all five AAST grades of severity for each of the 16 diseases. With ICD-9-CM, six diseases mapped into four categories of severity (instead of five), another six diseases into three categories of severity, and four diseases into only two categories of severity. With ICD-10-CM, five diseases mapped into four categories of severity, seven diseases into three categories, and four diseases into two categories. Two diseases mapped into discontinuous categories of grades (two in ICD-9-CM and one in ICD-10-CM). Although resolution is limited, ICD-9-CM and ICD-10-CM diagnosis codes might have some utility in roughly approximating the severity of the AAST grades in the absence of more precise information. These ICD mappings should be validated and refined before widespread use to characterize EGS disease severity. In the long-term, it may be desirable to develop alternatives to ICD-9-CM and ICD-10-CM codes for routine collection of disease severity characteristics. PMID:25909431

  3. Soil CO2 emissions in terms of irrigation management in an agricultural soil

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Acosta, José A.; María de la Rosa, José; Faz, Ángel; Domingo, Rafael; Pérez-Pastor, Alejandro; Ángeles Muñoz, María

    2014-05-01

    distributed in blocks. Each repetition had 15 rows with 15 trees per row. Soil CO2 emissions, moisture and temperature were monitored every 15 days. A soil sampling (0-30 cm) was carried out every three months, to determine the evolution of organic carbon, recalcitrant carbon, labile and soluble carbon, inorganic carbon, microbial biomass carbon, β-glucosidase and arylesterase enzyme activities, and organic functional groups measured by Fourier transform infrared spectroscopy (FTIR). A soil fractionation was carried out in all samples (<50, 50-250, 250-850, >2000 µm) to assess the weight and carbon content of each particles fraction in terms of irrigation treatments. Results showed that the application of deficit caused a significant decrease in CO2 emission rates, mainly in DI2, with rates 10 µg CO2-C m-2 s-1 lower than CT during this deficit period. When cumulative CO2-C released during one year was estimated, it was verified that water deficit contributed to decreases in the release of CO2, with a total release of 410 g CO2-C m-2 in CT, 355 g CO2-C m-2 in DI1, and 251 g CO2-C m-2 in DI2. This last treatment has supposed an annual reduction of 159 g CO2-C m-2 regarding CT. Soil properties, contrarily, showed no significant differences among treatments, with similar values in the C fractions and organic carbon quality, with an average organic C content of 4.5 kg m-2, 30 kg m-2 of inorganic C, a recalcitrance index of 57%, 1.40% of organic compounds solubility index and 160 g m-2 of microbial biomass C. There were no differences among particle sizes weigh and organic or inorganic carbon contents either. Thus, since no differences in quantity and quality of organic carbon was assess in soil with regard to irrigation treatment, it seems that longer periods are needed to assess shifts in soil properties related to carbon sequestration. Key words: carbon sequestration, CO2 emissions, organic carbon quality, irrigation

  4. Dust emissions of organic soils observed in the field and laboratory

    Technology Transfer Automated Retrieval System (TEKTRAN)

    According to the U.S. Soil Taxonomy, Histosols (also known as organic soils) are soils that are dominated by organic matter (>20% organic matter) in half or more of the upper 80 cm. These soils, when intensively cropped, are subject to wind erosion resulting in loss in crop productivity and degradat...

  5. Technogenic contaminations of the soil-plant cover in the Primorsky Krai, Russia

    NASA Astrophysics Data System (ADS)

    Molchanova, Inna; Pozolotina, Vera; Mikhailovskaya, Ludmila; Antonova, Elena; Zhuravlev, Yury; Timofeeva, Yana; Burdukovsky, Maxim

    2013-04-01

    All economical development of the countries carries out monitoring as with the aim to estimate impact of the industrial enterprises and nuclear-energetic complexes as consequences of the nuclear accidents. The investigation the region of the Far East due to proximity to epicentre of accident on Fukushima-1 NPP is of a great interest. The aim of this work are radioecological investigations and estimate technogenic load on the ecosystems of tightly populated plots of the shore zone of the Vladivostok region. Eight plots were located on the investigated territory. The tree fall, forest litters and soils were sampling from the profile cuts of layer by layer, up to 20 cm. The artificial radionuclides (Sr-90 and Cs-134,137), as heavy metals and microelements (Co, Cu, Zn, Pb and Mn) content in the prepared samples was determined. The stock of Sr-90 fluctuates from 0.3 to 1.3 kBq/m2 and Cs-137 was from 0.4 to 3.0 kBq/m2 in the examined soils. On the whole, the level of the radionuclides content in the soil cover is within the limits of the background that was formed in the belt between 50° and 60° of northern latitude. The presence in investigated samples of Cs-134 indicates to contribution of accidental fallout of Fukushima-1 into contamination of the components of the natural ecosystems. In a year's time after the accident the stock of this isotope in the soils was 0.01-0.20 kBq/m^2. It is by factor of 10-100 lower than the stock of Cs-137. Taking into account that the ratio Cs-134/Cs-137 on the moment of accident was equal to unity (1:1). It can be estimated the quantity of Cs-137 entering into environment during post - accident period. This quantity was an average 0.03-0.30 kBq/m2 (with correction on radionuclides decay). The observation for the state of the soil cover includes the estimate of the level and peculiarities of distribution in the soils of heavy metals and microelements. Their content in the soils is formed from Clarke number and additional industrial

  6. Effect of soil coarseness on soil base cations and available micronutrients in a semi-arid sandy grassland

    NASA Astrophysics Data System (ADS)

    Lü, Linyou; Wang, Ruzhen; Liu, Heyong; Yin, Jinfei; Xiao, Jiangtao; Wang, Zhengwen; Zhao, Yan; Yu, Guoqing; Han, Xingguo; Jiang, Yong

    2016-04-01

    Soil coarseness is the main process decreasing soil organic matter and threatening the productivity of sandy grasslands. Previous studies demonstrated negative effect of soil coarseness on soil carbon storage, but less is known about how soil base cations (exchangeable Ca, Mg, K, and Na) and available micronutrients (available Fe, Mn, Cu, and Zn) response to soil coarseness. In a semi-arid grassland of Northern China, a field experiment was initiated in 2011 to mimic the effect of soil coarseness on soil base cations and available micronutrients by mixing soil with different mass proportions of sand: 0 % coarse elements (C0), 10 % (C10), 30 % (C30), 50 % (C50), and 70 % (C70). Soil coarseness significantly increased soil pH in three soil depths of 0-10, 10-20 and 20-40 cm with the highest pH values detected in C50 and C70 treatments. Soil fine particles (smaller than 0.25 mm) significantly decreased with the degree of soil coarseness. Exchangeable Ca and Mg concentrations significantly decreased with soil coarseness degree by up to 29.8 % (in C70) and 47.5 % (in C70), respectively, across three soil depths. Soil available Fe, Mn, and Cu significantly decreased with soil coarseness degree by 62.5, 45.4, and 44.4 %, respectively. As affected by soil coarseness, the increase of soil pH, decrease of soil fine particles (including clay), and decline in soil organic matter were the main driving factors for the decrease of exchangeable base cations (except K) and available micronutrients (except Zn) through soil profile. Developed under soil coarseness, the loss and redistribution of base cations and available micronutrients along soil depths might pose a threat to ecosystem productivity of this sandy grassland.

  7. Root Patterns in Heterogeneous Soils

    NASA Astrophysics Data System (ADS)

    Dara, A.; Moradi, A. B.; Carminati, A.; Oswald, S. E.

    2010-12-01

    Heterogeneous water availability is a typical characteristic of soils in which plant roots grow. Despite the intrinsic heterogeneity of soil-plant water relations, we know little about the ways how plants respond to local environmental quality. Furthermore, increasing use of soil amendments as partial water reservoirs in agriculture calls for a better understanding of plant response to soil heterogeneity. Neutron radiography is a non-invasive imaging that is highly sensitive to water and root distribution and that has high capability for monitoring spatial and temporal soil-plant water relations in heterogeneous systems. Maize plants were grown in 25 x 30 x 1 cm aluminum slabs filled with sandy soil. On the right side of the compartments a commercial water absorbent (Geohumus) was mixed with the soil. Geohumus was distributed with two patterns: mixed homogeneously with the soil, and arranged as 1-cm diameter aggregates (Fig. 1). Two irrigation treatments were applied: sufficient water irrigation and moderate water stress. Neutron radiography started 10 days after planting and has been performed twice a day for one week. At the end of the experiment, the containers were opened, the root were removed and dry root weight in different soil segments were measured. Neutron radiography showed root growth tendency towards Geohumus treated parts and preferential water uptake from Geohumus aggregates. Number and length of fine lateral roots were lower in treated areas compared to the non-treated zone and to control soil. Although corn plants showed an overall high proliferation towards the soil water sources, they decreased production of branches and fine root when water was more available near the main root parts. However there was 50% higher C allocation in roots grown in Geohumus compartments, as derived by the relative dry weight of root. The preferential C allocation in treated regions was higher when plants grew under water stress. We conclude that in addition to the

  8. Landscape level differences in soil carbon and nitrogen: implications for soil carbon sequestration

    SciTech Connect

    Garten Jr, Charles T; Ashwood, Tom L

    2002-12-01

    The objective of this research was to understand how land cover and topography act, independently or together, as determinants of soil carbon and nitrogen storage over a complex terrain. Such information could help to direct land management for the purpose of carbon sequestration. Soils were sampled under different land covers and at different topographic positions on the mostly forested 14,000 ha Oak Ridge Reservation in Tennessee, USA. Most of the soil carbon stock, to a 40-cm soil depth, was found to reside in the surface 20 cm of mineral soil. Surface soil carbon and nitrogen stocks were partitioned into particulate ({ge}53 {micro}m) and mineral-associated organic matter (<53 {micro}m). Generally, soils under pasture had greater nitrogen availability, greater carbon and nitrogen stocks, and lower C:N ratios than soils under transitional vegetation and forests. The effects of topography were usually secondary to those of land cover. Because of greater soil carbon stocks, and greater allocation of soil carbon to mineral-associated organic matter (a long-term pool), we conclude that soil carbon sequestration, but not necessarily total ecosystem carbon storage, is greater under pastures than under forests. The implications of landscape-level variation in soil carbon and nitrogen for carbon sequestration are discussed at several different levels: (1) nitrogen limitations to soil carbon storage; (2) controls on soil carbon turnover as a result of litter chemistry and soil carbon partitioning; (3) residual effects of past land use history; and (4) statistical limitations to the quantification of soil carbon stocks.

  9. Using 137 Cs measurements to investigate the influence of erosion and soil redistribution on soil properties.

    PubMed

    Du, P; Walling, D E

    2011-05-01

    Information on the interaction between soil erosion and soil properties is an important requirement for sustainable management of the soil resource. The relationship between soil properties and the soil redistribution rate, reflecting both erosion and deposition, is an important indicator of this interaction. This relationship is difficult to investigate using traditional approaches to documenting soil redistribution rates involving erosion plots and predictive models. However, the use of the fallout radionuclide (137)Cs to document medium-term soil redistribution rates offers a means of overcoming many of the limitations associated with traditional approaches. The study reported sought to demonstrate the potential for using (137)Cs measurements to assess the influence of soil erosion and redistribution on soil properties (particle size composition, total C, macronutrients N, P, K and Mg, micronutrients Mn, Mo, Fe, Cu and Zn and other elements, including Ti and As). (137)Cs measurements undertaken on 52 soil cores collected within a 7 ha cultivated field located near Colebrooke in Devon, UK were used to establish the magnitude and spatial pattern of medium-term soil redistribution rates within the field. The soil redistribution rates documented for the individual sampling points within the field ranged from an erosion rate of -12.9 t ha(-1) yr(-1) to a deposition rate of 19.2 t ha(-1) yr(-1). Composite samples of surface soil (0-5 cm) were collected immediately adjacent to each coring point and these samples were analysed for a range of soil properties. Individual soil properties associated with these samples showed significant variability, with CV values generally lying in the range 10-30%. The relationships between the surface soil properties and the soil redistribution rate were analysed. This analysis demonstrated statistically significant relationships between some soil properties (total phosphorus, % clay, Ti and As) and the soil redistribution rate, but for

  10. Changes in soil carbon stocks in Brazil due to land use: paired site comparisons and a regional pasture soil survey

    NASA Astrophysics Data System (ADS)

    Assad, E. D.; Pinto, H. S.; Martins, S. C.; Groppo, J. D.; Salgado, P. R.; Evangelista, B.; Vasconcellos, E.; Sano, E. E.; Pavão, E.; Luna, R.; Camargo, P. B.; Martinelli, L. A.

    2013-03-01

    In this paper we calculated soil carbon stocks in Brazil using 17 paired sites where soil stocks were determined in native vegetation, pastures and crop-livestock systems (CPS), and in other regional samplings encompassing more than 100 pasture soils, from 6.58° S to 31.53° S, involving three major Brazilian biomes: Cerrado, Atlantic Forest, and the Pampa. The average native vegetation soil carbon stocks at 10 and 30 cm soil depth were equal to approximately 33 and 65 Mg ha-1, respectively. In the paired sites, carbon losses of 7.5 Mg ha-1 and 11.9 Mg ha-1 in CPS systems were observed at 10 cm and 30 cm soil depth averages, respectively. In pasture soils, carbon losses were similar and equal to 8.3 Mg ha-1 and 12.2 Mg ha-1 at 10 cm and 30 cm soil depths, respectively. The average soil δ13C under native vegetation at 10 and 30 cm depth were equal to -25.4‰ and -24.0‰, increasing to -19.6 ‰ and -17.7‰ in CPS, and to -18.9‰, and -18.3‰ in pasture soils, respectively; indicating an increasing contribution of C4 carbon in these agrosystems. In the regional survey of pasture soils, the soil carbon stock at 30 cm was equal to approximately 51 Mg ha-1, with an average δ13C value of -19.6‰. Key controllers of soil carbon stock at pasture sites were sand content and mean annual temperature. Collectively, both could explain approximately half of the variance of soil carbon stocks. When pasture soil carbon stocks were compared with the average soil carbon stocks of native vegetation estimated for Brazilian biomes and soil types by Bernoux et al. (2002) there was a carbon gain of 6.7 Mg ha-1, which is equivalent to a carbon gain of 15% compared to the carbon soil stock of the native vegetation. The findings of this study are consistent with differences found between regional comparisons like our pasture sites and local paired study sites in estimating soil carbon stocks changes due to land use changes.

  11. Application of Data Assimilation with the Root Zone Water Quality Model for Soil Moisture Profile Estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Ensemble Kalman Filter (EnKF), a popular data assimilation technique for non-linear systems was applied to the Root Zone Water Quality Model. Measured soil moisture data at four different depths (5cm, 20cm, 40cm and 60cm) from two agricultural fields (AS1 and AS2) in northeastern Indiana were us...

  12. Effect of soil structure on the growth of bacteria in soil quantified using CARD-FISH

    NASA Astrophysics Data System (ADS)

    Juyal, Archana; Eickhorst, Thilo; Falconer, Ruth; Otten, Wilfred

    2014-05-01

    It has been reported that compaction of soil due to use of heavy machinery has resulted in the reduction of crop yield. Compaction affects the physical properties of soil such as bulk density, soil strength and porosity. This causes an alteration in the soil structure which limits the mobility of nutrients, water and air infiltration and root penetration in soil. Several studies have been conducted to explore the effect of soil compaction on plant growth and development. However, there is scant information on the effect of soil compaction on the microbial community and its activities in soil. Understanding the effect of soil compaction on microbial community is essential as microbial activities are very sensitive to abrupt environmental changes in soil. Therefore, the aim of this work was to investigate the effect of soil structure on growth of bacteria in soil. The bulk density of soil was used as a soil physical parameter to quantify the effect of soil compaction. To detect and quantify bacteria in soil the method of catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH) was used. This technique results in high intensity fluorescent signals which make it easy to quantify bacteria against high levels of autofluorescence emitted by soil particles and organic matter. In this study, bacterial strains Pseudomonas fluorescens SBW25 and Bacillus subtilis DSM10 were used. Soils of aggregate size 2-1mm were packed at five different bulk densities in polyethylene rings (4.25 cm3).The soil rings were sampled at four different days. Results showed that the total number of bacteria counts was reduced significantly (P

  13. Comparison of electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil.

    PubMed

    Ottosen, Lisbeth M; Lepkova, Katarina; Kubal, Martin

    2006-09-01

    Electrokinetic remediation methods for removal of heavy metals from polluted soils have been subjected for quite intense research during the past years since these methods are well suitable for fine-grained soils where other remediation methods fail. Electrodialytic remediation is an electrokinetic remediation method which is based on applying an electric dc field and the use of ion exchange membranes that ensures the main transport of heavy metals to be out of the pollutes soil. An experimental investigation was made with electrodialytic removal of Cu from spiked kaolinite, spiked soil and industrially polluted soil under the same operational conditions (constant current density 0.2 mA/cm(2) and duration 28 days). The results of the present paper show that caution must be taken when generalising results obtained in spiked kaolinite to remediation of industrially polluted soils, as it was shown that the removal rate was higher in kaolinite than in both spiked soil and industrial polluted soil. The duration of spiking was found to be an important factor too, when attempting to relate remediation of spiked soil or kaolinite to remediation of industrially polluted soils. Spiking for 2 days was too short. However, spiking for 30 days resulted in a pattern that was more similar to that of industrially polluted soils with similar compositions both regarding sequential extraction and electrodialytic remediation result, though the remediation still progressed slightly faster in the spiked soil. Generalisation of remediation results to a variety of soil types must on the other hand be done with caution since the remediation results of different industrially polluted soils were very different. In one soil a total of 76% Cu was removed and in another soil no Cu was removed only redistributed within the soil. The factor with the highest influence on removal success was soil pH, which must be low in order to mobilize Cu, and thus the buffering capacity against acidification was

  14. Suppression of Rotylenchulus reniformis 122-cm Deep Endorses Resistance Introgression in Gossypium

    PubMed Central

    Robinson, A. F.; Akridge, J. R.; Bradford, J. M.; Cook, C. G.; Gazaway, W. S.; McGawley, E. C.; Starr, J. L.; Young, L. D.

    2006-01-01

    Nine sources of resistance to Rotylenchulus reniformis in Gossypium (cotton) were tested by measuring population density (Pf) and root-length density 0 to 122 cm deep. A Pf in the plow layer less than the autumn sample treatment threshold used by consultants was considered the minimum criterion for acceptable resistance, regardless of population density at planting (Pi). Other criteria were ample roots and a Pf lower than on the susceptible control, as in pot studies. In a Texas field in 2001 and 2002, no resistant accessions had Pf less than the control but all did in microplots into which nematodes from Louisiana were introduced. An environmental chamber experiment ruled out nematode genetic variance and implicated unknown soil factors. Pf in field experiments in Louisiana, Mississippi, and Alabama were below threshold for zero, six and four of the accessions and above threshold in the control. Gossypium arboreum A2–87 and G. barbadense GB-713 were the most resistant accessions. Results indicate that cultivars developed from these sources will suppress R. reniformis populations but less than in pots in a single season. PMID:19259448

  15. (Contaminated soil)

    SciTech Connect

    Siegrist, R.L.

    1991-01-08

    The traveler attended the Third International Conference on Contaminated Soil, held in Karlsruhe, Germany. The Conference was a status conference for worldwide research and practice in contaminated soil assessment and environmental restoration, with more than 1500 attendees representing over 26 countries. The traveler made an oral presentation and presented a poster. At the Federal Institute for Water, Soil and Air Hygiene, the traveler met with Dr. Z. Filip, Director and Professor, and Dr. R. Smed-Hildmann, Research Scientist. Detailed discussions were held regarding the results and conclusions of a collaborative experiment concerning humic substance formation in waste-amended soils.

  16. Tillage Effects on Soil Properties & Respiration

    NASA Astrophysics Data System (ADS)

    Rusu, Teodor; Bogdan, Ileana; Moraru, Paula; Pop, Adrian; Duda, Bogdan; Cacovean, Horea; Coste, Camelia

    2015-04-01

    Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and soil structural condition. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1) to assess the effects of tillage systems (Conventional System-CS, Minimum Tillage-MT, No-Tillage-NT) on soil compaction, soil temperature, soil moisture and soil respiration and 2) to establish the relationship that exists in changing soil properties. Three treatments were installed: CS-plough + disc; MT-paraplow + rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this, soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15 cm of soil depth and increased the soil temperature by 0.5-2.20C. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the two conservation tillage measures decreased soil respiration, with the best effects of no-tillage. An exceeding amount of CO2 produced in the soil and released into the atmosphere, resulting from aerobic processes of mineralization of organic matter (excessive loosening) is considered to be not only a way of increasing the CO2 in the atmosphere, but also a loss of

  17. Tracing metal pollution sources of plants and soils in Güzelhisar Basin of Aegean Region, Turkey

    NASA Astrophysics Data System (ADS)

    Czarnecki, Sezin; Görsch, Carolin; Colak Esetlili, Bihter; Esetlili, Tolga; Tepecik, Mahmut; Kurucu, Yusuf; Anac, Dilek; Düring, Rolf-Alexander

    2016-04-01

    The study area Güzelhisar Basin is 6 km far from the city Aliaga, Aegean Region in the west part of Turkey which represents a rather industrialized area having five large iron and steel mills, but also areas of agriculture. A grid system of 2.5 km to the east and 2.5 km to the west of the Güzelhisar Stream was studied. The area was grouped into three main areas as West, Middle, and East region. Every 500 meters soil samples were taken after the rainfall (April-May) in 2014 from the GPS determined points at 0-30 and 30-60 cm depth. Soil reaction of the study area was determined within the range from 5.87 to 6.61. Even though, the West and the Middle regions had weak carbonate concentrations, the East region was poor in carbonates and relatively high electrical conductivity was measured. Topsoil contamination was examined by all investigated elements with the exception of Cd. An increase in pseudo total metal contents of Cr, Cu, Mn, Ni, and Zn was observed with the increasing distance from the coast with a simultaneous decrease in pH. Moreover, high plant metal concentrations [mg kg‑¹, ± sd] were detected for B [20.7 ± 23.9], Cu [7.99 ± 5.17], Mn (79.3 ± 89.2), Ni (3.50 ± 3.48), and Zn (25.5 ± 20.1). Transfer of the elements from soil to plants increased in the following order: Co < As < Cr < Pb < Mn < Ni < Cu < Zn < Cd << B.

  18. [Construction effect of fertile cultivated layer in black soil].

    PubMed

    Han, Xiao-zeng; Zou, We