Science.gov

Sample records for 0-10 cm soil

  1. 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...

  2. Poliovirus retention in 75-cm soil cores after sewage and rainwater application

    SciTech Connect

    Landry, E.F.; Vaughn, J.M.; Penello, W.F.

    1980-12-01

    The adsorption rate of a guanidine-resistant strain of poliovirus LSc 2ab was measured in Long Island soils with in situ field cores (10.1 by 75 cm). The test virus was chosen because it exhibited soil adsorption and elution characteristics of a number of non-polioviruses. After the inoculation of cores with seeded sewage effluent at a 1-cm/h infiltration rate, cores were extracted, fractionated, and analyzed for total plaque-forming units per each 5-cm fraction. The results showed that 77% of the viruses were adsorbed in the first 5 cm of soil. An additional 11% were found in the 5- to 10-cm fraction, and a total of 96% of the viruses were adsorbed by 25 cm. The remaining 4% were uniformly distributed over the next 50 cm of soil, with a minimum of 0.23% in each soil section. Few viruses (< 0.22%) were observed in core filtrates. Analysis of the viral distribution pattern in seeded cores, after an application of a single rinse of either sewage effluent or rainwater, indicated that large-scale viral mobilization was absent. However, localized areas of viral movement were noted in both of the rinsed cores, with the rainwater rinsed cores exhibiting more extensive movement. All mobilized viruses were resorbed at lower core depths.

  3. 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.

  4. Assessing soil hydrological variability at the cm- to dm-scale using air permeameter measurements

    NASA Astrophysics Data System (ADS)

    Beerten, K.; Vandersmissen, N.; Rogiers, B.; Mallants, D.

    2012-04-01

    Soils and surficial sediments are crucial elements in the hydrological cycle since they are the medium through which infiltrating precipitation percolates to the aquifer. At the same time, soil horizons and shallow stratigraphy may act as hydraulic barriers that can promote runoff or interflow and hamper deep infiltration. For most catchments little is known about the small-scale horizontal and vertical variability of soil hydrological properties. Such information is however required to calculate detailed soil water flow paths and estimate small scale spatial variability in recharge and run-off. We present the results from field air permeameter measurements to assess the small-scale variability of saturated hydraulic conductivity in heterogeneous 2-D soil profiles. To this end, several outcrops in the unsaturated zone (sandy soils with podzolisation) of an interfluve in the Kleine Nete river catchment (Campine area, Northern Belgium) were investigated using a hand-held permeameter. Measurements were done each 10 cm on ~ 2 x 1 m or ~ 2 x 0.5 m grids. The initial results of the measurements (air permeability Kair; millidarcy) are recalculated to saturated hydraulic conductivity (Ks; m/s) using specific transfer functions (Loll et al., 1999; Iversen et al., 2003). Validation of the results is done with independent lab-based constant head Ks measurements. The results show that field based Ks values generally range between 10-3 m/s and 10-7 m/s within one profile, but extremely high values (up to 10-1 m/s) have been measured as well. The lowest values are found in the organic- and silt-rich Bh horizon of podzol soils observed within the profiles (~ 10-6-10-7m/s), while the highest values are observed in overlying dune sands less than 40 cm deep (up to 10-3 m/s with outliers to 10-1 m/s). Comparison of field and laboratory based Ks data reveals there is fair agreement between both methods, apart from several outliers. Scatter plots indicate that almost all points

  5. Thermal emission measurements 2000-400/cm (5-25 micrometers) of Hawaiian palagonitic soils and their implications for Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bell, James F., III

    1995-01-01

    The thermal emision of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 micrometers (2000 to 400/cm) for several partical size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approximately 20% in the short wavelength region (5 to 6.5 mirometers, 2000 to 1500/cm), and is more subdued, less than 4%, at longer wavelengths. The strengths of features present in the infrared spectra of Mars cannot be solely provided by emissivity variations of palagonite; some other material or mechanism must provide additional absorptions(s).

  6. 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.

  7. Diagnosing the strength of soil temperature in the land atmosphere interactions over Asia based on RegCM4 model

    NASA Astrophysics Data System (ADS)

    Liu, Di; Yu, Zhongbo; Zhang, Jianyun

    2015-07-01

    This study aims to investigate the soil temperature atmosphere (ST Atm) coupling strength and their influence on the subsequent climate anomalies over Asia based on a regional climate model RegCM4 with both statistical analysis method and numerical experiments. The major findings are as follows: (1) The soil temperature precipitation (ST P) coupling is quite weak and spatially scattered from both RegCM4 output and GLDAS data in each season with the only obvious signals existing over the north India region in summer season according to the RegCM4 output; the soil temperature 2m air temperature (ST T2m) coupling is strong and spatially continuous with the India (in spring, summer and autumn seasons), South Indochina (in spring and summer seasons) and part of North China (in summer season) standing out as hotspots. (2) The soil temperature evapotranspiration (ST ET) and soil temperature evaporative fraction (ST EF) coupling almost resembles the same spatial patterns and magnitude in each season. Both the ET and EF play an important role in linking ST P coupling in each season, but not in the ST T2m coupling. The hotspots of ST T2m coupling outweigh the areas with strong ST ET and ST EF coupling. Only the India and Indochina in each season are recognized by the RegCM4 while the Indochina and west Asia in spring, north India, Indochina and part of mid-high latitudes in summer season pinpointed by GLDAS data show consistent strong ST T2m coupling with significant ST ET and ST EF coupling. This finding demonstrates the complicated ST Atm coupling. (3) The ST anomalies prescribed at the first step of each season can only persist a short time (within 5 days) over most part of the study area while the fixed one-month anomalies can last longer (approximately 2 months with colder anomalies and 45 days with warmer anomalies in tropical regions). (4) The impact of ST anomalies on subsequent precipitation is quite weak and can be ignored over most part of the study area, while

  8. Thermal emission measurements 2000-400 cm(exp -1) (5-25 microns) of Hawaiian palagonitic soils and their implications for Mars

    NASA Technical Reports Server (NTRS)

    Roush, Ted L.; Bell, James F., III

    1995-01-01

    The thermal emission of two palagonitic soils, common visible and near infrared spectral analogs for bright soils on Mars, was measured over the wavelength range of 5 to 25 microns (2000 to 400 cm(exp -1) for several particle size separates. All spectra exhibit emissivity features due to vibrations associated with H2O and SiO. The maximum variability of emissivity is approx. = 20% in the short wavelength region (5 to 6.5 microns, 2000 to 1500 cm(exp -1)), and is more subdued, < 4%, at longer wavelengths. The strengths of features present in infrared spectra of Mars cannot be solely provided by emissivity variations of palagonite; some other material or mechanism must provide additional absorption(s).

  9. 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

  10. Responses of soil microbial communities to experimental warming in alpine grasslands on the qinghai-tibet plateau.

    PubMed

    Zhang, Bin; Chen, Shengyun; He, Xingyuan; Liu, Wenjie; Zhao, Qian; Zhao, Lin; Tian, Chunjie

    2014-01-01

    Global surface temperature is predicted to increase by at least 1.5°C by the end of this century. However, the response of soil microbial communities to global warming is still poorly understood, especially in high-elevation grasslands. We therefore conducted an experiment on three types of alpine grasslands on the Qinghai-Tibet Plateau to study the effect of experimental warming on abundance and composition of soil microbial communities at 0-10 and 10-20 cm depths. Plots were passively warmed for 3 years using open-top chambers and compared to adjacent control plots at ambient temperature. Soil microbial communities were assessed using phospholipid fatty acid (PLFA) analysis. We found that 3 years of experimental warming consistently and significantly increased microbial biomass at the 0-10 cm soil depth of alpine swamp meadow (ASM) and alpine steppe (AS) grasslands, and at both the 0-10 and 10-20 cm soil depths of alpine meadow (AM) grasslands, due primarily to the changes in soil temperature, moisture, and plant coverage. Soil microbial community composition was also significantly affected by warming at the 0-10 cm soil depth of ASM and AM and at the 10-20 cm soil depth of AM. Warming significantly decreased the ratio of fungi to bacteria and thus induced a community shift towards bacteria at the 0-10 cm soil depth of ASM and AM. While the ratio of arbuscular mycorrhizal fungi to saprotrophic fungi (AMF/SF) was significantly decreased by warming at the 0-10 cm soil depth of ASM, it was increased at the 0-10 cm soil depth of AM. These results indicate that warming had a strong influence on soil microbial communities in the studied high-elevation grasslands and that the effect was dependent on grassland type.

  11. Phylogenetic changes in soil bacterial communities as CRP land is converted back to cropland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We assessed the impacts of conversion of Conservation Reserve Program (CRP) land to continuous cropland on soil bacterial communities. Soil samples (0-10cm and 10-30cm) were collected from 3 long-term (>20 y) CRP fields and 3 fields recently (within 1-2 y in 2012) converted from CRP (>20 y) to dryla...

  12. CORRELATIONS BETWEEN PESTICIDE TRANSFORMATION RATE AND MICROBIAL RESPIRATION ACTIVITY IN SOIL OF DIFFERENT ECOSYSTEMS

    EPA Science Inventory

    Cecil sandy loam soils (ultisol) from forest (coniferous and deciduous), pasture, and arable ecosystems were sampled (0-10 cm) in the vicinity of Athens, GA, USA. Soil from each site was subdivided into three portions, consisting of untreated soil (control) as well as live and s...

  13. Variations in Soil Microbial Biomass Carbon and Soil Dissolved Organic Carbon in the Re-Vegetation of Hilly Slopes with Purple Soil.

    PubMed

    Yang, Ning; Zou, Dongsheng; Yang, Manyuan; Lin, Zhonggui

    2016-01-01

    Crust restoration is increasingly being done but we lack quantitative information on soil improvements. The study aimed to elucidate the dynamics involving soil microbial biomass carbon and soil dissolved organic carbon in the re-vegetation chronosequences of a hillslope land with purple soil in Hengyang, Hunan Province. The soil can cause serious disasters with both soil erosion and seasonal drought, and also becomes a typical representative of ecological disaster area in South China. Using the space-for-time method, we selected six typical sampling plots, designated as follows: grassplot community, meadow thicket community, frutex community, frutex and arbor community, arbor community, and top-level vegetation community. These plots were established to analyze the changes in soil microbial biomass carbon, soil microbial quotien, dissolved organic carbon, dissolved organic carbon/soil organic carbon, and soil basal respiration in 0-10, 10-20, and 20-40 cm soil layers. The relationships of these parameters with soils physic-chemical properties were also determined. The ecological environment of the 6 plant communities is similar and typical; they denoted six different successive stages of restoration on hillslopes with purple soils in Hengyang, Hunan Province. The soil microbial biomass carbon and soil basal respiration contents decreased with increasing soil depth but increased with re-vegetation. By contrast, soil microbial quotient increased with increasing soil depth and re-vegetation. From 0-10 cm soil layer to 20-40 cm soil layer, the dissolved organic carbon content decreased in different re-vegetation stages. In the process of re-vegetation, the dissolved organic carbon content increased in the 0-10 and 10-20 cm soil layers, whereas the dissolved organic carbon content decreased after an initial increase in the 20-40 cm soil layers. Meanwhile, dissolved organic carbon/soil organic carbon increased with increasing soil depth but decreased with re

  14. 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.

  15. Effects of tillage on the Fe oxides activation in soil

    NASA Astrophysics Data System (ADS)

    Chi, Guangyu; Chen, Xin; Shi, Yi; Wang, Jun; Zheng, Taihui

    2009-07-01

    Since mid-1950s, the wetland ecosystems in Sanjiang Plain of Northeast China have been experiencing greater changes in land use, which had negative effects on the soil environments. This study assessed the effects of soil tillage on the activation of soil Fe in the region. The test ecosystems included natural wetland, paddy field and upland field converted from wetland. Soil samples at the depths of 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, 40-60 cm, 60-90 cm and 90-120 cm were collected from each of the ecosystems for the analysis of vertical distribution of soil pH, organic carbon, chelate Fe oxides and Fe(II). The results showed that the conversion of wetland into paddy field and upland field induced a decrease of organic carbon content in 0-10 cm soil layer by 61.8% (P <0.05) and 70.0% (P < 0.05), respectively. The correlations among iron forms and soil organic carbon showed that chelate Fe oxides and Fe(II) was correlated positively with soil organic carbon and chelate ratio had a more positive relationship with organic carbon than chelate Fe oxides and Fe(II). The results of chelate Fe oxides, Fe(II) and chelate ratio of Fe suggested that reclamation could prevent the Fe activation and organic matter is credited for having an important influence on the process of Fe activation.

  16. Soil bacterial and fungal community responses across a conservation reserve program chronosequence in Texas high plains region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We investigated changes in soil bacterial and fungal communities with increasing restoration time across a Conservation Reserve Program chronosequence (CRP) on fine sandy loam soils in the Texas high plains region. Soil samples (0-10cm) were collected in 2012 and 2014 from seven dryland croplands (0...

  17. Pyrogenic carbon in Australian soils.

    PubMed

    Qi, Fangjie; Naidu, Ravi; Bolan, Nanthi S; Dong, Zhaomin; Yan, Yubo; Lamb, Dane; Bucheli, Thomas D; Choppala, Girish; Duan, Luchun; Semple, Kirk T

    2017-02-16

    Pyrogenic carbon (PyC), the combustion residues of fossil fuel and biomass, is a versatile soil fraction active in biogeochemical processes. In this study, the chemo-thermal oxidation method (CTO-375) was applied to investigate the content and distribution of PyC in 30 Australian agricultural, pastoral, bushland and parkland soil with various soil types. Soils were sampled incrementally to 50cm in 6 locations and at another 7 locations at 0-10cm. Results showed that PyC in Australian soils typically ranged from 0.27-5.62mg/g, with three Dermosol soils ranging within 2.58-5.62mg/g. Soil PyC contributed 2.0-11% (N=29) to the total organic carbon (TOC), with one Ferrosol as high as 26%. PyC was concentrated either in the top (0-10cm) or bottom (30-50cm) soil layers, with the highest PyC:TOC ratio in the bottom (30-50cm) soil horizon in all soils. Principal component analysis - multiple linear regression (PCA-MLR) suggested the silt-associated organic C factor accounted for 38.5% of the variation in PyC. Our findings suggest that PyC is an important fraction of the TOC (2.0-11%, N=18) and chemically recalcitrant organic C (ROC) obtained by chemical C fractionation method accounts for a significant proportion of soil TOC (47.3-84.9%, N=18). This is the first study comparing these two methods, and it indicates both CTO-375 and C speciation methods can determine a fraction of recalcitrant organic C. However, estimated chemically recalcitrant organic carbon pool (ROC) was approximately an order of magnitude greater than that of thermally stable organic carbon (PyC).

  18. 28 CFR 0.10 - Attorney General's Advisory Committee of U.S. Attorneys.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... the Associate Attorney General in formulating new programs for improvement of the criminal justice... U.S. Attorneys. 0.10 Section 0.10 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Office of the Attorney General § 0.10 Attorney General's Advisory Committee of...

  19. 28 CFR 0.10 - Attorney General's Advisory Committee of U.S. Attorneys.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... the Associate Attorney General in formulating new programs for improvement of the criminal justice... U.S. Attorneys. 0.10 Section 0.10 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Office of the Attorney General § 0.10 Attorney General's Advisory Committee of...

  20. 28 CFR 0.10 - Attorney General's Advisory Committee of U.S. Attorneys.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... the Associate Attorney General in formulating new programs for improvement of the criminal justice... U.S. Attorneys. 0.10 Section 0.10 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Office of the Attorney General § 0.10 Attorney General's Advisory Committee of...

  1. 28 CFR 0.10 - Attorney General's Advisory Committee of U.S. Attorneys.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... the Associate Attorney General in formulating new programs for improvement of the criminal justice... U.S. Attorneys. 0.10 Section 0.10 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Office of the Attorney General § 0.10 Attorney General's Advisory Committee of...

  2. 28 CFR 0.10 - Attorney General's Advisory Committee of U.S. Attorneys.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... the Associate Attorney General in formulating new programs for improvement of the criminal justice... U.S. Attorneys. 0.10 Section 0.10 Judicial Administration DEPARTMENT OF JUSTICE ORGANIZATION OF THE DEPARTMENT OF JUSTICE Office of the Attorney General § 0.10 Attorney General's Advisory Committee of...

  3. Shallow (0-10) seismic investigation of a distressed earthen levee, New Orleans, USA

    NASA Astrophysics Data System (ADS)

    Lorenzo, J. M.; Hicks, J.; Vera, E. E.

    2009-12-01

    Both deep- and near-surface hydrogeologic processes can contribute to the structural failure of artificial earthen levees. Recently, seismic geophysical methods have attempted to develop a proxy for engineering shear strength, by mapping changes in the transmission velocity of shear waves. High fluid content may indicate both weak, under-compacted materials and/or organic-rich sediments. In the absence of electromagnetic methods, Vp/Vs ratios can be used as good indicators of variations in the fluid (water, and air or gas) saturation. Cone penetration borehole tests measure the resistance of soils to penetration of the cone tip and its frictional sliding that can be correlated to sediment types and their physical properties. A distressed section of an artificial earthen levee, suitable for seismic investigation, lies ~15 km S of the city of New Orleans, Louisiana, USA. Open curvilinear fissures, 10 cm wide, 30 cm deep, and up to 100 m in length, exist along the crest at two sites. Between September 2007 and February 2008 we collect horizontally (SH) polarized shear and compressional wave (P) data in pseudo-walkaway tests for the upper 100 m of the subsurface along the protected (west) side of the earthen levee, within 30 m of its crest. One profile lies parallel and adjacent to the damaged levee crest and, for reference, two profiles lie nearby adjacent to undamaged portions of the artificial earthen levee. In the first ~30 m of sediment below the lower delta plain of the Greater New Orleans area, a complex and dynamic interaction of freshwater and marine sedimentary environments juxtaposes a diverse set of facies. We combine of Vp and Vs velocity maps, sedimentary environment interpretations, and cone-penetration-derived sediment/soil and laboratory-derived physical properties to locate possible zones of high fluid concentration, (and perhaps seepage), weak engineering materials, and natural foundation soil shear strength. Under the distressed portion of the

  4. 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.

  5. Cooperative effects of field traffic and organic matter treatments on some compaction-related soil properties

    NASA Astrophysics Data System (ADS)

    Mujdeci, Metin; Isildar, Ahmet Ali; Uygur, Veli; Alaboz, Pelin; Unlu, Husnu; Senol, Huseyin

    2017-02-01

    Soil compaction is a common problem of mineral soils under conventional tillage practices. Organic matter addition is an efficient way of reducing the effects of field traffic in soil compaction. The aim of this study was to investigate the effects of number of tractor passes (one, three, and five) on depth-dependent (0-10 and 10-20 cm) penetration resistance, bulk density, and porosity of clay-textured soil (Typic Xerofluvent) under organic vegetable cultivation practices in the 2010-2013 growing seasons. Fields were treated with farmyard manure (FYM, 35 t ha-1), green manure (GM; common vetch, Vicia sativa L.), and conventional tillage (CT). The number of tractor passes resulted in increases in bulk density and penetration resistance (CT > GM > FYM), whereas the volume of total and macropores decreased. The maximum penetration resistance (3.60 MPa) was recorded in the CT treatment with five passes at 0-10 cm depth, whereas the minimum (1.64 MPa) was observed for the FYM treatment with one pass at 10-20 cm depth. The highest bulk density was determined as 1.61 g cm-3 for the CT treatment with five passes at 10-20 cm depth; the smallest value was 1.25 g cm-3 in the FYM treatment with only one pass at 0-10 cm depth. The highest total and macropore volumes were determined as 0.53 and 0.16 cm3 cm-3 respectively at 0-10 cm depth for the FYM treatment with one pass. The volume of micropores (0.38 cm3 cm-3) was higher at 0-10 cm depth for the FYM treatment with three passes. It can be concluded that organic pre-composted organic amendment rather than green manure is likely to be more efficient in mitigating compaction problems in soil.

  6. Retention of tannin-C is associated with decreased soluble-N and increased cation exchange capacity in a broad range of soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phenolic plant compounds, called tannins, can be retained by soil and affect nutrient cycling but have been studied in only a few soils. Soils (0-10 cm) from locations across the United States and Canada were treated with water (Control) or solutions containing procyanidin, catechin, tannic acid, ß-...

  7. Urbanization in China drives soil acidification of Pinus massoniana forests.

    PubMed

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-09-24

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10 cm (for ammonium N(NH4+(-N)), P < 0.05; for nitrate N(NO3-(-N)), P < 0.01) and 10-20 cm (for NO3-(-N), P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0-10 cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment.

  8. Urbanization in China drives soil acidification of Pinus massoniana forests

    NASA Astrophysics Data System (ADS)

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-09-01

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10cm (for ammonium N (-N), P < 0.05 for nitrate N (-N), P < 0.01) and 10-20 cm (for -N, P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0-10cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment.

  9. Soil Microbial Communities associated to Plant Rhizospheres in an Organic Farming System in Alabama

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbial communities under different organic crop rhizospheres (0-10 and 10-20 cm) were characterized using fatty acid methyl ester (FAME) and pyrosequencing techniques. The soil was a silt loam (12.8% clay, 71.8% silt and15.4% sand). Soils at this site are characterized as having pH of ~6.53,...

  10. Soil microbial communities associated to plant rhizospheres in an organic farming system in Alabama

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbial communities under different organic crop rhizospheres (0-10 and 10-20 cm) were characterized using fatty acid methyl ester (FAME) and pyrosequencing techniques. The soil was a silt loam (12.8% clay, 71.8% silt and15.4% sand). Soils at this site are characterized as having pH of ~6.53, ...

  11. [Effects of nitrogen addition on soil physico-chemical properties and enzyme activities in desertified steppe].

    PubMed

    Su, Jie-Qiong; Li, Xin-Rong; Bao, Jing-Ting

    2014-03-01

    To investigate the impacts of nitrogen (N) enrichment on soil physico-chemical property and soil enzyme activities in desert ecosystems, a field experiment by adding N at 0, 1.75, 3.5, 7, or 14 g N x m(-2) a(-1) was conducted in a temperate desert steppe in the southeastern fringe of the Tengger Desert. The results showed that N addition led to accumulations of total N, NO(3-)-N, NH(4+)-N, and available N in the upper soil (0-10 cm) and subsoil (10-20 cm), however, reductions in soil pH were observed, causing soil acidification to some extent. N addition pronouncedly inhibited soil enzyme activities, which were different among N addition levels, soil depths, and years, respectively. Soil enzyme activities were significantly correlated with the soil N level, soil pH, and soil moisture content, respectively.

  12. 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.

  13. Freeze-Thaw Cycles Effects on Soil Compaction in a Clay Loam

    NASA Astrophysics Data System (ADS)

    Jabro, J.; Evans, R.; Iversen, W.

    2012-04-01

    Inappropriate soil management practices and heavier farm machinery and equipment have led to an increase in soil compaction in the last two decades prompting increased global concern regarding the impact of soil compaction on crop production and soil quality in modern mechanized agriculture. A 3-yr comprehensive study was established to evaluate the dynamic of freeze-thaw cycles on soil compaction in a clay loam soil. Plots of frozen soils were compared with plots where soils were prevented from freezing with electrically heated blankets commonly used on concrete. Results showed that frequent freeze-thaw cycles over the winter alleviated a majority of soil compaction at the 0 - 20 cm depth. Soil penetration resistance in compacted soils was reduced by 73 and 68% over the winter at the 0 - 10 and 10 - 20 cm depths, respectively, due to dynamic effects of freeze-thaw cycles on soil structure and particles configuration. In unfrozen compacted soils, the penetration resistance was also reduced by 50 and 60% over winter at the 0 - 10 and 10 - 20 cm depths, respectively, due to the biology of soil, microbial activity, and disruptive effects of shrink-swell cycles. These results have demonstrated of how repeated freeze-thaw cycles can alleviate soil compaction, alter soil physical quality and create optimal soil conditions required for profitable growth of agricultural crops. The results from this study will save growers considerable time, money and energy currently required to alleviate soil compaction using other methods such as sub-soiling and deep tillage. We believe that Mother Nature provides ways to reverse soil compaction and improve soil structure and aggregation through the dynamic of freeze-thaw cycles that soils in Montana and other parts of the country go through each year. We concluded that the Mother Nature is the most effective and cheapest way to alleviate soil compaction.

  14. Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska.

    PubMed

    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

    2014-08-01

    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 (NH4+ and NO3-). 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.

  15. [Profile distribution and storage of soil organic carbon in a black soil as affected by land use types].

    PubMed

    Hao, Xiang-xiang; Han, Xiao-zeng; Li, Lu-jun; Zou, Wen-xiu; Lu, Xin-chun; Qiao, Yun-fa

    2015-04-01

    Taking soils in a long-term experimental field over 29 years with different land uses types, including arable land, bare land, grassland and larch forest land as test materials, the distribution and storage of soil organic carbon (SOC) in the profile (0-200 cm) in typical black soil (Mollisol) region of China were investigated. The results showed that the most significant differences in SOC content occurred in the 0-10 cm surface soil layer among all soils with the order of grassland > arable land > larch forest land > bare land. SOC contents at 10-120 cm depth were lower in arable land as compared with the other land use types. Compared with arable land, grassland could improve SOC content obviously. SOC content down to a depth of 60 cm in grassland was significantly higher than that in arable land. The content of SOC at 0-10 cm in bare land was significantly lower than that in arable land. Although there were no significant differences in SOC content at 0-20 cm depth between larch forestland and arable land, the SOC contents at 20-140 cm depth were generally higher in larch forestland than that in arable land. In general, SOC content showed a significantly negative relationship with soil pH, bulk density, silt and clay content and an even stronger significantly positive relationship with soil total N content and sand content. The SOC storage in arable land at 0-200 cm depth was significantly lower than that in the other three land use types, which was 13.6%, 11.4% and 10.9% lower than in grassland, bare land and larch forest land, respectively. Therefore, the arable land of black soil has a great potential for sequestering C in soil and improving environmental quality.

  16. The accumulation of organic carbon in mineral soils by afforestation of abandoned farmland.

    PubMed

    Wei, Xiaorong; Qiu, Liping; Shao, Mingan; Zhang, Xingchang; Gale, William J

    2012-01-01

    The afforestation of abandoned farmland significantly influences soil organic carbon (OC). However, the dynamics between OC inputs after afforestation and the original OC are not well understood. To learn more about soil OC dynamics after afforestation of farmland, we measured the soil OC content in paired forest and farmland plots in Shaanxi Province, China. The forest plots had been established on farmland 18, 24, 48, 100, and 200 yr previously. The natural (13)C abundance of soil organic matter was also analyzed to distinguish between crop- and forest-derived C in the afforested soils. We observed a nonlinear accumulation of total OC in the 0-80 cm depth of the mineral soil across time. Total soil OC accumulated more rapidly under forest stands aged 18 to 48 yr than under forest stands aged 100 or 200 yrs. The rate of OC accumulation was also greater in the 0-10 cm depth than in the 10-80 cm depth. Forest-derived OC in afforested soils also accumulated nonlinearly across time, with the greatest increase in the 0-20 cm depth. Forest-derived OC in afforest soils accounted for 52-86% of the total OC in the 0-10 cm depth, 36-61% of the total OC in the 10-20 cm depth, and 11-50% of the total OC in the 20-80 cm depth. Crop-derived OC concentrations in the 0-20 cm depth decreased slightly after afforestation, but there was no change in crop-derived OC concentrations in the 20-80 cm depth. The results of our study support the claim that afforestation of farmland can sequester atmospheric CO(2) by increasing soil OC stocks. Changes in the OC stocks of mineral soils after afforestation appear to be influenced mainly by the input of forest-derived C rather than by the loss of original OC.

  17. [Effects of land use and abandonment on soil labile organic carbon in the Karst region of southwest China].

    PubMed

    Liao, Hong-Kai; Li, Juan; Long, Jian; Zhang, Wen-Juan; Liu, Ling-Fei

    2014-01-01

    Effects of land use and land abandonment on labile organic carbon (LOC) in whole soils and different aggregate sizes were studied by sampling analysis of the soils in some typical land uses of the Karst region, southwest China. Results showed that the content and degree of dispersion of labile organic carbon decreased with soil depth, and the content of LOC was highly significant (P < 0.01) in 0-10 cm than in 10-20 cm and 20-30 cm. In the 0-10 cm soil layer, the content of LOC distribution in different aggregates was higher in the < 0.25 mm size, while no obvious changes of LOC among aggregates were found in the 10-20 cm and 20-30 cm depths. In different land use patterns, the LOC was the highest in paddy whether in whole soils or aggregates, followed by shrub, and the lowest in abandoned 3 years grassland. Within-between principal component analysis showed that the accumulation characters between land use and LOC were in the order of paddy > shrub > abandoned 15 years grassland = dry land > abandoned 3 years grassland, the content of LOC increased by 20.3% as compared to dryland, and had reached 80% of the content of shrub in abandoned 15 years grassland at the 0-10 cm depth, indicating that at the early stage of land abandonment, the natural recovery of carbon is relatively slow, while with the abandonment time increase, the carbon sink effect gradually appear.

  18. 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

  19. Room Temperature Antiferromagnetic Ordering of Nanocrystalline Tb1.90Ni0.10O3

    NASA Astrophysics Data System (ADS)

    Mandal, J.; Dalal, M.; Sarkar, B. J.; Chakrabarti, P. K.

    2017-02-01

    Nanocrystalline Ni-doped terbium oxide (Tb1.90Ni0.10O3) has been synthesized by the co-precipitation method followed by annealing at 700°C for 6 h in vacuum. The crystallographic phase and the substitution of Ni2+ ions in the lattice of Tb2O3 are confirmed by Rietveld analysis of the x-ray diffraction pattern using the software MAUD. High-resolution transmission electron microscopy is also carried out to study the morphology of the sample. Magnetic measurements are carried out at different temperatures from 5 K to 300 K using a superconducting quantum interference device (SQUID) magnetometer. The dependence of the magnetization of Tb1.90Ni0.10O3 as a function of temperature ( M- T) and magnetic field ( M- H) suggests the presence of both paramagnetic and antiferromagnetic phase at room temperature, but antiferromagnetic phase dominates below ˜120 K. The lack of saturation in the M- H curve and good fitting of the M- T curve by the Johnston formula also indicate the presence of both paramagnetic and antiferromagnetic phase at room temperature. Interestingly, an antiferromagnetic to ferromagnetic phase transition is observed below ˜40 K. The result also shows a high value of magnetization at 5 K.

  20. 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

  1. Quantitative and qualitative responses of soil organic carbon to six years of extreme soil warming in a subarctic grassland in Iceland

    NASA Astrophysics Data System (ADS)

    Poeplau, Christopher; Leblans, Niki I. W.; Sigurdsson, Bjarni D.; Kätterer, Thomas

    2016-04-01

    Terrestrial carbon cycle feedbacks to global warming are expected, but constitute a major uncertainty in climate models. Soils in northern latitudes store a large proportion of the total global biosphere carbon stock and might thus become a strong source of CO2 when warmed. Long-term in situ observations of warming effects on soil organic carbon (SOC) dynamics are indispensable for an in depth understanding of the involved processes. We investigated the effect of six years of soil warming on SOC quantity and quality in a geothermally heated grassland soil in Iceland. We isolated five fractions of SOC along an extreme soil warming gradient of +0 to +40°C. Those fractions vary conceptually in turnover time from active to passive in the following order: particulate organic matter (POM), dissolved organic carbon (DOC), SOC in sand and stable aggregates (SA), SOC in silt and clay (SC-rSOC) and resistant SOC (rSOC). Soil warming of 1°C increased bulk SOC by 22% (0-10 cm) and 27% (20-30 cm), while further warming led to exponential SOC depletion of up to 79% (0-10 cm) and 74% (20-30) in the most heated plots (~ +40°C). Only the SA fraction was more sensitive than the bulk soil, with 93% (0-10 cm) and 86% (20-30 cm) losses and with the highest relative enrichment in 13C (+1.6‰ in 0-10 cm and +1.3‰ in 20-30 cm). In addition, the mass of the SA fraction did significantly decline along the warming gradient, which we explained by devitalization of aggregate binding mechanisms. As a consequence, the fine SC fraction mass increased with warming which explained the relative enrichment of presumably more slow-cycling SOC (R2=0.61 in 0-10 cm and R2=0.92 in 20-30 cm). Unexpectedly, no difference was observed between the responses of SC-rSOC (slow-cycling) and rSOC (passive) to warming. Furthermore, the 13C enrichment by trophic fractionation in the passive rSOC fraction was equal to this in the bulk soil. We therefore conclude that the sensitivity of SOC to warming was not a

  2. [Study on soil enzyme activities and microbial biomass carbon in greenland irrigated with reclaimed water].

    PubMed

    Pan, Neng; Hou, Zhen-An; Chen, Wei-Ping; Jiao, Wen-Tao; Peng, Chi; Liu, Wen

    2012-12-01

    The physicochemical properties of soils might be changed under the long-term reclaimed water irrigation. Its effects on soil biological activities have received great attentions. We collected surface soil samples from urban green spaces and suburban farmlands of Beijing. Soil microbial biomass carbon (SMBC), five types of soil enzyme activities (urease, alkaline phosphatase, invertase, dehydrogenase and catalase) and physicochemical indicators in soils were measured subsequently. SMBC and enzyme activities from green land soils irrigated with reclaimed water were higher than that of control treatments using drinking water, but the difference is not significant in farmland. The SMBC increased by 60.1% and 14.2% than those control treatments in 0-20 cm soil layer of green land and farmland, respectively. Compared with their respective controls, the activities of enzymes in 0-20 cm soil layer of green land and farmland were enhanced by an average of 36.7% and 7.4%, respectively. Investigation of SMBC and enzyme activities decreased with increasing of soil depth. Significantly difference was found between 0-10 cm and 10-20 cm soil layer in green land. Soil biological activities were improved with long-term reclaimed water irrigation in Beijing.

  3. Rovibrational bound states of SO2 isotopologues. I: Total angular momentum J = 0-10

    NASA Astrophysics Data System (ADS)

    Kumar, Praveen; Ellis, Joseph; Poirier, Bill

    2015-04-01

    Isotopic variation of the rovibrational bound states of SO2 for the four stable sulfur isotopes 32-34,36S is investigated in comprehensive detail. In a two-part series, we compute the low-lying energy levels for all values of total angular momentum in the range J = 0-20. All rovibrational levels are computed, to an extremely high level of numerical convergence. The calculations have been carried out using the ScalIT suite of parallel codes. The present study (Paper I) examines the J = 0-10 rovibrational levels, providing unambiguous symmetry and rovibrational label assignments for each computed state. The calculated vibrational energy levels exhibit very good agreement with previously reported experimental and theoretical data. Rovibrational energy levels, calculated without any Coriolis approximations, are reported here for the first time. Among other potential ramifications, this data will facilitate understanding of the origin of mass-independent fractionation of sulfur isotopes in the Archean rock record-of great relevance for understanding the "oxygen revolution".

  4. Dissolved organic C and N pools in soils amended with composted and thermally-dried sludge as affected by soil tillage systems and sampling depth

    NASA Astrophysics Data System (ADS)

    García-Gil, Juan Carlos; Soler-Rovira, Pedro Angel; García López de Sa, Esther; Polo, Alfredo

    2013-04-01

    Soil tillage practices exert a significant influence on the dynamic of soluble organic C and N pools, affecting nutrient cycling in agricultural systems by enhancing its mineralization through microbial activities or stabilization in soil microaggregates, which contribute to mitigate greenhouse gases emissions. The objective of the present research was to determine the influence of three different soil management systems (moldboard plowing, chisel and no-tillage) and the application of composted sludge (CS) and thermally-dried sewage sludge (TSS) obtained from wastewater treatment processes on dissolved organic C (water-soluble organic C -WSOC-, carbohydrates, phenolic compounds) and soluble N (total-N, NH4+, NO3-) pools in a long-term field experiment (27 years) conducted on a sandy-loam soil at the experimental station "La Higueruela" (40° 03'N, 4° 24'W) under semi-arid conditions. Both organic amendments were applied at a rate of 30 tonnes per hectare prior to tillage practices. Unamended soils were used as control for each tillage system. Soil sampling was performed two months after tillage practices at the following depths for each treatment: 0-10 cm, 10-20 cm and 20-30 cm. Results obtained for unamended soils showed that no-tillage management increased total-N, NH4+ and NO3- contents at the 0-10 cm depth samples, meanwhile WSC and carbohydrates contents were larger at 20-30 cm depth samples in both moldboard and no-tillage plots. CS and TSS-amended soils presented a general increase in soluble C and N compounds, being significantly higher in TSS-amended soils, as TSS contains a great amount of labile organic C and N substrates due to the lack of stabilization treatment. TSS-amended soils under no-tillage and chisel plowing showed larger N, NH4+ and NO3- content at the 0-10 cm samples, meanwhile moldboard management exhibited larger NH4+ and NO3- content at 10-20 and 20-30 cm samples, possibly due to the incorporation of TSS at deeper depths (20-40 cm). CS

  5. Spatial Distribution Of Cs-137 In Surface Soils On Some Central Rhodopes Regions

    SciTech Connect

    Hristov, Hr. G.; Srentz, A. K.; Balabanov, N. P.

    2007-04-23

    The subject of investigation are soils from region around village Kiselchovo, town Smolyan, villages Narechen, Bachkovo, Laki, Kosovo, Dobralak, Central Rhodopes region. The samples have been collected from natural soils at a depth of 0-10 cm. The samples have been analyzed for the content of technogenical radionuclide Cs-137. The measurements were taken by precise gamma ray spectrometer. Based on the conducted research an inference can be made that there are radioactive contamination (up to 30 times over the background level)

  6. Spatial Distribution Of Cs-137 In Surface Soils On Some Central Rhodopes Regions

    NASA Astrophysics Data System (ADS)

    Hristov, Hr. G.; Srentz, A. K.; Balabanov, N. P.

    2007-04-01

    The subject of investigation are soils from region around village Kiselchovo, town Smolyan, villages Narechen, Bachkovo, Laki, Kosovo, Dobralak, Central Rhodopes region. The samples have been collected from natural soils at a depth of 0-10 cm. The samples have been analyzed for the content of technogenical radionuclide Cs-137. The measurements were taken by precise gamma ray spectrometer. Based on the conducted research an inference can be made that there are radioactive contamination (up to 30 times over the background level).

  7. 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

  8. [Transportation and risk assessment of heavy metal pollution in water-soil from the Riparian Zone of Daye Lake, China].

    PubMed

    Zhang, Jia-quan; Li, Xiu; Zhang, Quan-fa; Li, Qiong; Xiao, Wen-sheng; Wang, Yong-kui; Zhang, Jian-chun; Gai, Xi-guang

    2015-01-01

    Each 20 water samples and soil samples (0-10 cm, 10-20 cm) were collected from the riparian zone of Daye Lake in dry season during March 2013. Heavy metals (Cu, Ph, Cd, Zn) have been detected by flame atomic absorption spectrometric (FAAS). The results showed that the average concentrations of Cu, Pb, Cd, Zn in the water were 7.14, 25.94, 15.72 and 37.58 microg x L(-1), respectively. The concentration of Cu was higher than the five degree of the surface water environment quality standard. The average concentrations of Cu, Pb, Cd, Zn in soil(0-10 cm) were 108.38, 53.92, 3.55, 139.26 mg x kg(-1) in soil (10-20 cm) were 93.00, 51.72, 2.08, 171.00 mg x kg(-1), respectively. The Cd concentrations were higher than the three grade value of the national soil environment quality standard. The transportation of Pb from soil to water was relatively stable, and Zn was greatly influenced by soil property and the surrounding environment from soil to water. The transformation of heavy metal in west riparian zone was higher than that of east riparian zone. The potential environmental risk was relatively high. Cu, Pb, Cd, Zn were dominated by residue fraction of the modified BCR sequential extraction method. The overall migration order of heavy metal element was: Pb > Cu > Cd > Zn. There were stronger transformation and higher environmental pollution risk of Cu, Pb. The index of assessment and potential ecological risk coefficient indicated that heavy metal pollution in soil (0-10 cm) was higher than the soil (10-20 cm), Cd was particularly serious.

  9. 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].

  10. 17 CFR 240.0-10 - Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act. 240.0-10 Section 240.0-10 Commodity... Regulatory Flexibility Act. For purposes of Commission rulemaking in accordance with the provisions...

  11. 17 CFR 240.0-10 - Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act. 240.0-10 Section 240.0-10 Commodity... Regulatory Flexibility Act. For purposes of Commission rulemaking in accordance with the provisions...

  12. 17 CFR 270.0-10 - Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act. 270.0-10 Section 270.0-10 Commodity... Regulatory Flexibility Act. (a) General. For purposes of Commission rulemaking in accordance with...

  13. 17 CFR 270.0-10 - Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act. 270.0-10 Section 270.0-10 Commodity... Regulatory Flexibility Act. (a) General. For purposes of Commission rulemaking in accordance with...

  14. 17 CFR 240.0-10 - Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act. 240.0-10 Section 240.0-10 Commodity... Regulatory Flexibility Act. For purposes of Commission rulemaking in accordance with the provisions...

  15. 17 CFR 270.0-10 - Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act. 270.0-10 Section 270.0-10 Commodity... Regulatory Flexibility Act. (a) General. For purposes of Commission rulemaking in accordance with...

  16. 17 CFR 240.0-10 - Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act. 240.0-10 Section 240.0-10 Commodity... Regulatory Flexibility Act. For purposes of Commission rulemaking in accordance with the provisions...

  17. 17 CFR 270.0-10 - Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act. 270.0-10 Section 270.0-10 Commodity... Regulatory Flexibility Act. (a) General. For purposes of Commission rulemaking in accordance with...

  18. 17 CFR 270.0-10 - Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Small entities under the Investment Company Act for purposes of the Regulatory Flexibility Act. 270.0-10 Section 270.0-10 Commodity... Regulatory Flexibility Act. (a) General. For purposes of Commission rulemaking in accordance with...

  19. EVALUATION OF THE EFFECTIVENESS OF RIPARIAN ZONE RESTORATION IN THE SOUTHERN APPALACHIANS BY ASSESSING SOIL MICROBIAL POPULATIONS

    EPA Science Inventory

    Microbial biomass, nitrifiers and denitrifiers in surface soil (0?10 cm) were quantified in a riparian zone restoration project at Coweeta, North Carolina, USA. Four treatments are included in this study: (1) a degraded (+N) riparian zone with continued compaction, vegetation rem...

  20. 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.

  1. [Effects of Slope Position and Soil Horizon on Soil Microbial Biomass and Abundance in Karst Primary Forest of Southwest China].

    PubMed

    Feng, Shu-zhen; Su, Yi-rong; Zhang, Wei; Chen, Xiang-bi; He, Xun-yang

    2015-10-01

    To explore the effects of slope position and soil horizon on soil microbial biomass and abundance, chloroform fumigation extraction methods and real-time fluorescence-based quantitative PCR (Real-time PCR) were adopted to quantify the changes of soil microbial biomass C, N and abundance of bacteria and fungi, respectively. Soil samples were harvested from three horizons along profile, i. e., leaching horizon (A, 0-10 cm), transitional horizon (AB, 30-50 cm) and alluvial horizon (B, 70-100 cm), which were collected from the upper, middle and lower slope positions of a karst primary forest ecosystem. The results showed that slope position, soil horizon and their interaction significantly influenced the soil microbial biomass and abundance (P < 0.05). Different from A horizon, where SMBC was greater in lower than in upper slope position (P < 0.05), SMBC in AB and B horizons were highest in middle slope position. Similarly, SMBN was greater in lower than in upper slope position for A, AB and B horizons. Besides soil bacterial abundance in B horizon and fungal abundance in AB layer, the middle slope position had the highest value for all the three soil horizons (P < 0.05). Stepwise regression analysis showed that soil organic carbon, available nitrogen and pH were the key factors responsible for SMBC and SMBN variation, respectively, while the important factors responsible for the variation of bacteria abundance were available nitrogen and available phosphorus, and that for fungi abundance variation were available potassium.

  2. [Soil sandy desertification and salinization and their interrelationships in Yanghuang irrigated area of Hongsipu, Ningxia of northwest China].

    PubMed

    Yang, Xin-guo; Song, Nai-ping

    2011-09-01

    By the methods of controlled and typical sampling, this paper analyzed the texture, salinization characteristics, cation exchange capacity (CEC), and their correlations in the 0-40 cm soil profiles of corn land, medlar land, and non-utilized land in Yanghuang irrigated area of Hongsipu, Northwest China. Under controlled sampling, the salt content in the soil profiles was 0.69-1.30 g x kg(-1) (except in non-utilized land where the 0-10 cm soil salt content was up to 1.74 g x kg(-1)), with no obvious salinization. The sodium adsorption ratio and exchangeable sodium percentage in the 20-40 cm soil layer of medlar land were 12.18 and 14.1%, respectively, and the total content of clay and silt in the 0-40 cm soil profile of medlar land was up to 37.3% whereas that in the 0-20 cm soil layer of corn land was only 13.5%. In the 20-40 cm soil layer of corn land, the indices of sandy desertification and salinization had significant correlations under controlled sampling but no correlations under typical sampling, while the CEC and the sandy desertification and salinization indices had significant correlations under typical sampling. In different land use types in the study area, soil sandy desertification and salinization had complicated interrelationships, and CEC could be used as the indicator for the changes in soil environmental quality.

  3. Effects of switchgrass cultivars and intraspecific differences in root structure on soil carbon inputs and accumulation

    SciTech Connect

    Adkins, Jaron; Jastrow, Julie D.; Morris, Geoffrey P.; Six, Johan; de Graaff, Marie-Anne

    2016-01-01

    Switchgrass (Panicum virgatum L), a cellulosic biofuel feedstock, may promote soil C 21 accumulation compared to annual cropping systems by increasing the amount and retention of 22 root-derived soil C inputs. The aim of this study was to assess how different switchgrass 23 cultivars impact soil C inputs and retention, whether these impacts vary with depth, and whether 24 specific root length (SRL) explains these impacts. We collected soil to a depth of 30 cm from six 25 switchgrass cultivars with root systems ranging from high to low SRL. The cultivars (C4 species) 26 were grown for 27 months on soils previously dominated by C3 plants, allowing us to use the 27 natural difference in 13C isotopic signatures between C3 soils and C4 plants to quantify 28 switchgrass-derived C accumulation. The soil was fractionated into coarse particulate organic 29 matter (CPOM), fine particulate organic matter (FPOM), silt, and clay-sized fractions. We 30 measured total C and plant-derived C in all soil fractions across all depths. The study led to two main results: (1) bulk soil C concentrations beneath switchgrass cultivars varied by 40% in the 0-32 10 cm soil depth and by 70% in the 10-20 cm soil depth, and cultivars with high bulk soil C 33 concentrations tended to have relatively high C concentrations in the mineral soil fractions and 34 relatively low C concentrations in the POM fractions; (2) there were significant differences in 35 switchgrass-derived soil C between cultivars at the 0-10 cm depth, where soil C inputs ranged 36 from 1.2 to 3.2 mg C g-1 dry soil. There was also evidence of a positive correlation between SRL 37 and switchgrass-derived C inputs when one outlier data point was removed. These results 38 indicate that switchgrass cultivars differentially impact mechanisms contributing to soil C accumulation.

  4. Sensitivity of soil carbon fractions and their specific stabilization mechanisms to extreme soil warming in a subarctic grassland.

    PubMed

    Poeplau, Christopher; Kätterer, Thomas; Leblans, Niki I W; Sigurdsson, Bjarni D

    2017-03-01

    Terrestrial carbon cycle feedbacks to global warming are major uncertainties in climate models. For in-depth understanding of changes in soil organic carbon (SOC) after soil warming, long-term responses of SOC stabilization mechanisms such as aggregation, organo-mineral interactions and chemical recalcitrance need to be addressed. This study investigated the effect of 6 years of geothermal soil warming on different SOC fractions in an unmanaged grassland in Iceland. Along an extreme warming gradient of +0 to ~+40 °C, we isolated five fractions of SOC that varied conceptually in turnover rate from active to passive in the following order: particulate organic matter (POM), dissolved organic carbon (DOC), SOC in sand and stable aggregates (SA), SOC in silt and clay (SC-rSOC) and resistant SOC (rSOC). Soil warming of 0.6 °C increased bulk SOC by 22 ± 43% (0-10 cm soil layer) and 27 ± 54% (20-30 cm), while further warming led to exponential SOC depletion of up to 79 ± 14% (0-10 cm) and 74 ± 8% (20-30) in the most warmed plots (~+40 °C). Only the SA fraction was more sensitive than the bulk soil, with 93 ± 6% (0-10 cm) and 86 ± 13% (20-30 cm) SOC losses and the highest relative enrichment in (13) C as an indicator for the degree of decomposition (+1.6 ± 1.5‰ in 0-10 cm and +1.3 ± 0.8‰ in 20-30 cm). The SA fraction mass also declined along the warming gradient, while the SC fraction mass increased. This was explained by deactivation of aggregate-binding mechanisms. There was no difference between the responses of SC-rSOC (slow-cycling) and rSOC (passive) to warming, and (13) C enrichment in rSOC was equal to that in bulk soil. We concluded that the sensitivity of SOC to warming was not a function of age or chemical recalcitrance, but triggered by changes in biophysical stabilization mechanisms, such as aggregation.

  5. Soil organic carbon beneath croplands and re-established grasslands in the North Dakota Prairie Pothole Region.

    PubMed

    Phillips, Rebecca L; Eken, Mikki R; West, Mark S

    2015-05-01

    Grassland ecosystems established under the conservation reserve program (CRP) in the Prairie Pothole Region (PPR) currently provide soil conservation and wildlife habitat services. We aimed to determine if these lands also sequester soil organic carbon (SOC), as compared with neighboring croplands across multiple farms in the North Dakota PPR. We sampled soil from small plots at 17 private farms in the central North Dakota PPR, where long-term (≥15 years) grasslands managed under the CRP were paired with neighboring annual croplands. Cores were collected to 100 cm and split into 0-10, 10-20, 20-30, 30-40, 40-70, and 70-100 cm soil depth layers. We hypothesized the effect of land use on soil organic carbon (SOC), root carbon (C), and bulk density would be greatest near the surface. For 0-10 and 10-20 cm layers, grasslands managed under the CRP were lower in bulk density and higher in SOC. From 0 to 70 cm, grasslands managed under the CRP were higher in root C. Average (±standard error) SOC for re-established grasslands and croplands was 25.39 (0.91) and 21.90 (1.02), respectively, for the 0-10 cm soil layer and 19.88 (0.86) and 18.31 (0.82), respectively, for the 10-20 soil layer. Compared to croplands, re-established grasslands sampled in the North Dakota PPR were 3-13 % lower in bulk density and 9-16 % higher in SOC from 0 to 20 cm, while root C was 2-6 times greater from 0 to 70 cm.

  6. Soil Organic Carbon Beneath Croplands and Re-established Grasslands in the North Dakota Prairie Pothole Region

    NASA Astrophysics Data System (ADS)

    Phillips, Rebecca L.; Eken, Mikki R.; West, Mark S.

    2015-05-01

    Grassland ecosystems established under the conservation reserve program (CRP) in the Prairie Pothole Region (PPR) currently provide soil conservation and wildlife habitat services. We aimed to determine if these lands also sequester soil organic carbon (SOC), as compared with neighboring croplands across multiple farms in the North Dakota PPR. We sampled soil from small plots at 17 private farms in the central North Dakota PPR, where long-term (≥15 years) grasslands managed under the CRP were paired with neighboring annual croplands. Cores were collected to 100 cm and split into 0-10, 10-20, 20-30, 30-40, 40-70, and 70-100 cm soil depth layers. We hypothesized the effect of land use on soil organic carbon (SOC), root carbon (C), and bulk density would be greatest near the surface. For 0-10 and 10-20 cm layers, grasslands managed under the CRP were lower in bulk density and higher in SOC. From 0 to 70 cm, grasslands managed under the CRP were higher in root C. Average (±standard error) SOC for re-established grasslands and croplands was 25.39 (0.91) and 21.90 (1.02), respectively, for the 0-10 cm soil layer and 19.88 (0.86) and 18.31 (0.82), respectively, for the 10-20 soil layer. Compared to croplands, re-established grasslands sampled in the North Dakota PPR were 3-13 % lower in bulk density and 9-16 % higher in SOC from 0 to 20 cm, while root C was 2-6 times greater from 0 to 70 cm.

  7. [Dynamics of unprotected soil organic carbon with the restoration process of Pinus massoniana plantation in red soil erosion area].

    PubMed

    Lü, Mao-Kui; Xie, Jin-Sheng; Zhou, Yan-Xiang; Zeng, Hong-Da; Jiang, Jun; Chen, Xi-Xiang; Xu, Chao; Chen, Tan; Fu, Lin-Chi

    2014-01-01

    By the method of spatiotemporal substitution and taking the bare land and secondary forest as the control, we measured light fraction and particulate organic carbon in the topsoil under the Pinus massoniana woodlands of different ages with similar management histories in a red soil erosion area, to determine their dynamics and evaluate the conversion processes from unprotected to protected organic carbon. The results showed that the content and storage of soil organic carbon increased significantly along with ages in the process of vegetation restoration (P < 0.01). The unprotected soil organic carbon content and distribution proportion to the total soil organic carbon increased significantly (P < 0.05) after 7-11 years' restoration but stabilized after 27 and 30 years of restoration. It suggested that soil organic carbon mostly accumulated in the form of unprotected soil organic carbon during the initial restoration period, and reached a stable level after long-term vegetation restoration. Positive correlations were found between restoration years and the rate constant for C transferring from the unprotected to the protected soil pool (k) in 0-10 cm and 10-20 cm soil layers, which demonstrated that the unprotected soil organic carbon gradually transferred to the protected soil organic carbon in the process of vegetation restoration.

  8. [Vertical distribution and possible sources of polycyclic aromatic hydrocarbon in sewage area soil].

    PubMed

    Yao, Lin-Lin; Zhang, Cai-Xiang; Li, Jia-Le; Liao, Xiao-Ping; Wang, Yan-Xin

    2013-04-01

    Nine profile soil samples were collected from Xiaodian sewage irrigation area, Taiyuan city, China. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) were analyzed by gas chromatography equipped with a mass spectrometry detector (GC/ MS). The rank order of the average concentrations of PAHs in the 0-10 cm upper soil layer was background area < swamp area < groundwater irrigation area < sewage irrigation area. The concentrations of PAHs in most profile soils decreased with the increase of depth, and the PAHs were mainly accumulated in the surface soil layer (0-40 cm). 4-6 rings of PAHs were mainly accumulated in the 0-50 cm soil layer, and the accumulation capacity in groundwater-irrigation area was better than that in sewage irrigation area. The correlation between different rings of PAHs and TOC was positive (r(max) = 0.791, P = 0), and the same situation was found for PAHs and sand (r(max) = 0. 882, P = 0). The correlation between PAHs and pH was negative (r(min) = -0.1, P = 0.702). The main source of PAHs in the surface soil layer (0-40 cm) of study area was coal combustion. There were two pollution ways of PAHs in soil, one was settled into soil directly, the other was first settled into water and absorbed on the surface of solid particles, and then got enrichment in soil as irrigation water flew.

  9. Structural, electrical and magnetic properties of Bi{sub 0.90}La{sub 0.10}Fe{sub 0.90}Co{sub 0.10}O{sub 3} ceramics

    SciTech Connect

    Muneeswaran, M.; Giridharan, N. V.; Bhuvaneswari, S.; Senguttuvan, G.

    2014-04-24

    Multiferroic Bi{sub 0.90}La{sub 0.10}Fe{sub 0.90}Co{sub 0.10}O{sub 3} ceramics have been synthesized via soft chemical co-precipitation method. From the X-ray diffraction analysis, ceramic powder sintered at 600°C was found to be single phase belonging to the rhombohedral structure with R3c space group confirmed by Rietveld analysis. Further, dielectric, Leakage and magnetic studies were performed at room temperature.

  10. Effects of Heavy, Tracked-Vehicle Disturbance on Forest Soil Properties at Fort Benning, Georgia

    SciTech Connect

    Garten, C.T.,JR.

    2004-05-20

    The purpose of this report is to describe the effects of heavy, tracked-vehicle disturbance on various measures of soil quality in training compartment K-11 at Fort Benning, Georgia. Predisturbance soil sampling in April and October of 2002 indicated statistically significant differences in soil properties between upland and riparian sites. Soil density was less at riparian sites, but riparian soils had significantly greater C and N concentrations and stocks than upland soils. Most of the C stock in riparian soils was associated with mineral-associated organic matter (i.e., the silt + clay fraction physically separated from whole mineral soil). Topographic differences in soil N availability were highly dependent on the time of sampling. Riparian soils had higher concentrations of extractable inorganic N than upland soils and also exhibited significantly greater soil N availability during the spring sampling. The disturbance experiment was performed in May 2003 by driving a D7 bulldozer through the mixed pine/hardwood forest. Post-disturbance sampling was limited to upland sites because training with heavy, tracked vehicles at Fort Benning is generally confined to upland soils. Soil sampling approximately one month after the experiment indicated that effects of the bulldozer were limited primarily to the forest floor (O-horizon) and the surface (0-10 cm) mineral soil. O-horizon dry mass and C stocks were significantly reduced, relative to undisturbed sites, and there was an indication of reduced mineral soil C stocks in the disturbance zone. Differences in the surface (0-10 cm) mineral soil also indicated a significant increase in soil density as a result of disturbance by the bulldozer. Although there was some tendency for greater soil N availability in disturbed soils, the changes were not significantly different from undisturbed controls. It is expected that repeated soil disturbance over time, which will normally occur in a military training area, would simply

  11. Stratification and Storage of Soil Organic Carbon and Nitrogen as Affected by Tillage Practices in the North China Plain.

    PubMed

    Zhao, Xin; Xue, Jian-Fu; Zhang, Xiang-Qian; Kong, Fan-Lei; Chen, Fu; Lal, Rattan; Zhang, Hai-Lin

    2015-01-01

    Tillage practices can redistribute the soil profiles, and thus affects soil organic carbon (SOC), and its storage. The stratification ratio (SR) can be an indicator of soil quality. This study was conducted to determine tillage effects on the profile distribution of certain soil properties in winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) systems in the North China Plain (NCP). Three tillage treatments, including no till (NT), rotary tillage (RT), and plow tillage (PT), were established in 2001 in Luancheng County, Hebei Province. The concentration, storage, and SR of SOC and soil total nitrogen (TN) were assessed in both the wheat and maize seasons. Compared with RT and PT, the mean SRs for all depth ratios of SOC under NT increased by 7.85% and 30.61% during the maize season, and by 14.67% and 30.91% during the wheat season, respectively. The SR of TN for 0-5:30-50 cm increased by 140%, 161%, and 161% in the maize season, and 266%, 154%, and 122% in the wheat season compared to the SR for 0-5:5-10 cm under NT, RT and PT, respectively. The data indicated that SOC and TN were both concentrated in the surface-soil layers (0-10 cm) under NT but were distributed relatively evenly through the soil profile under PT. Meanwhile, the storage of SOC and TN was higher under NT for the surface soil (0-10 cm) but was higher under PT for the deeper soil (30-50 cm). Furthermore, the storage of SOC and TN was significantly related to SR of SOC and TN along the whole soil profile (P<0.0001). Therefore, SR could be used to explain and indicate the changes in the storage of SOC and TN. Further, NT stratifies SOC and TN, enhances the topsoil SOC storage, and helps to improve SOC sequestration and soil quality.

  12. Investigation of Soil Erosion and Phosphorus Transport within an Agricultural Watershed

    NASA Astrophysics Data System (ADS)

    Klik, A.; Jester, W.; Muhar, A.; Peinsitt, A.; Rampazzo, N.; Mentler, A.; Staudinger, B.; Eder, M.

    2003-04-01

    In a 40 ha agricultural used watershed in Austria, surface runoff, soil erosion and nutrient losses are measured spatially distributed with 12 small erosion plots. Crops during growing season 2002 are canola, corn, sunflower, winter wheat, winter barley, rye, sugar beets, and pasture. Canopy height and canopy cover are observed in 14-day intervals. Four times per year soil water content, shear stress and random roughness of the surface are measured in a 25 x 25 m grid (140 points). The same raster is sampled for soil texture analyses and content of different phosphorus fractions in the 0-10 cm soil depth. Spatially distributed data are used for geostatistical analysis. Along three transects hydrologic conditions of the hillslope position (top, middle, foot) are investigated by measuring soil water content and soil matrix potential. After erosive events erosion features (rills, deposition, ...) are mapped using GPS. All measured data will be used as input parameters for the Limburg Soil Erosion Model (LISEM).

  13. Hydraulic and mechanical properties of soil aggregates under organic and conventional soil management

    NASA Astrophysics Data System (ADS)

    Wójciga, A.; Kuś, J.; Turski, M.; Lipiec, J.

    2009-04-01

    Variation in hydraulic and mechanical properties of soil aggregates is an important factor affecting water storage and infiltration because the large inter-aggregate pores are dewatered first and the transport of water and solutes is influenced by the properties of the individual aggregates and contacts between them. A high mechanical stability of soil aggregates is fundamental for the maintenance of proper tilth and provides stable traction for farm implements, but limit root growth inside aggregates. The aggregate properties are largely influenced by soil management practices. Our objective was to compare the effects of organic and conventional soil management on hydraulic and mechanical properties of soil aggregates. Experimental fields subjected to long-term organic (14 years) and conventional managements were located on loamy soil at the Institute of Soil Science and Plant Cultivation - National Research Institute in Pulawy, Poland. Soil samples were collected from two soil depths (0-10 cm and 10-20 cm). After air-drying, two size fractions of soil aggregates (15-20 and 30-35 mm) were manually selected and kept in the dried state in a dessicator in order to provide the same boundary conditions. Following properties of the aggregates were determined: porosity (%) using standard wax method, cumulative infiltration Q (mm3 s-1) and sorptivity S (mm s -1/2) of water and ethanol using a tube with a sponge inserted at the tip, wettability (by comparison of sorptivity of water and ethanol) using repellency index R, crushing strength q (MPa) using strength testing device (Zwick/Roell) and calculated by Dexter's formula. All properties were determined in 15 replicates for each treatment, aggregates size and depth. Organic management decreased porosity of soil aggregates and ethanol infiltration. All aggregates revealed rather limited wettability (high repellency index). In most cases the aggregate wettability was lower under conventional than organic soil management

  14. [Effects of fertilization on the P accumulation and leaching in vegetable greenhouse soil].

    PubMed

    Zhao, Ya-jie; Zhao, Mu-qiu; Lu, Cai-yan; Shi, Yi; Chen, Xin

    2015-02-01

    A packed soil column experiment was conducted to investigate the effect of different fertilization practices on phosphorus (P) accumulation and leaching potential in a vegetable greenhouse soil with different fertility levels. The results showed that the leaching loss of total P in the leachates elevated with the increment of leaching time while the accumulative leaching loss of total P was relatively low, indicating P was mainly accumulated in the soil instead of in the leachate. At the end of the leaching experiment, soil fertility and fertilization treatment affected the content of total phosphorus and Olsen-P significantly. Compared with the low-level-fertility soil, the contents of total P and Olsen-P increased by 14.3% and 12.2% in the medium-level-fertility soil, 33.3% and 37.7% in the high-level-fertility soil. Total P in the combined application of poultry manure and chemical fertilizer (M+NPK) was elevated by 5.7% and 4.3%, compared with the NPK and M treatment. Compared with NPK treatment, Olsen-P in M and M + NPK treatments augmented by 13.0% and 3.1%, respectively. Soil total P and Olsen-P mainly accumulated in the 0-10 cm and 10-20 cm soil layers, and much less in the 20-40 cm soil layer.

  15. Changes of soil organic matter and microbial activity in irrigated and non irrigated olive groves

    NASA Astrophysics Data System (ADS)

    Kavvadias, Victor; Papadopoulou, Maria; Theocharopoulos, Sideris; Vavoulidou, Evagelia; Doula, Maria; Reppas, Spiros

    2014-05-01

    The implementation of olive cultivation techniques in Greece has not been systematically tested under the prevailing Mediterranean conditions. A LIFE+ project was initiated (oLIVE-CLIMA; LIFE 11/ENV/000942) aiming to introduce new management practices in olive tree crops that lead to increased carbon dioxide uptake by plants as well as carbon sequestration from the atmosphere and reverse the trend of soil organic matter decline, erosion and desertification. This paper presents data on soil organic matter and microbial activity from a soil campaign in a pilot region in Greece, and particularly in the area of Chora, prefecture of Messinia, South west Peloponnese. The soil campaign took place during the period December 2012-February 2013. Twelve soil parcels of olive groves were selected (6 irrigated and 6 rainfed) and in each soil parcel six composite soil samples were taken from 0-10 cm depth at equal intervals along a straight line of the trunk of the tree to the middle of the distance from the nearest tree of the next tree series. The first three samples were under olive tree canopy. An additional composite sample was taken at depth of 10-40 cm. Soil samples were analyzed for soil physicochemical and biological properties. In this study results for total organic carbon (TOC), soil basal microbial respiration (BR), microbial biomass C (MB-C) from the region of Messinia, are presented. Organic matter was determined by dichromate oxidation. The microbial activity was measured by the amount of CO2 evolution, while microbial biomass C was determined by substrate-induced respiration, after the addition of glucose. The results showed considerable differences in TOC, BR and MB-C associated with the sampling position and soil depth. The higher TOC, BR and MB-C values, in most cases, were determined in samples taken from points under the canopy, but not close to the tree trunk compared to the sampling points outside the canopy. This indicates the positive effect of

  16. Physical and chemical properties of feedlot pen surfaces located on moderately coarse- and moderately fine-textured soils in southern Alberta.

    PubMed

    Miller, Jim J; Curtis, Tony; Larney, Francis J; McAllister, Tim A; Olson, Barry M

    2008-01-01

    Southern Alberta has the highest density of feedlot cattle in Canada, and there is a concern that leaching of water and contaminants may be greater for feedlots located on coarser-textured than finer-textured soils. Our objective was to determine if infiltration and leaching were greater for a 4-yr-old feedlot located on a moderately coarse-textured (MC) soil compared with two feedlots located on moderately fine-textured (MF) soils (5- and 52-yr-old pens). Various soil physical properties of feedlot pen surfaces were measured, including field-saturated hydraulic conductivity (K(fs)) and near-saturated hydraulic conductivity at -0.9 and -3.9 cm water potential. Selected chemical properties of feedlot soil layers were measured, as well as the chloride content of the soil profile (0-100 cm). Mean K(fs), K(-0.9), and K(-3.9) values were not significantly (P > 0.10) greater at the MC site than the two MF sites, indicating no evidence of greater infiltration on coarser-textured soils. In addition, mean K(fs), K(-0.9), and K(-3.9) values of soils within feedlot pens at all three sites were significantly (P < or = 0.10) reduced by 46 to 78% compared with soil outside the pens. Depth of chloride accumulation was greatest at the 52-yr-old feedlot on MF soil (60-70 cm), followed by 4-yr-old feedlot on MC soil (40-50 cm) and 5-yr-old feedlot on MF soil (30-40 cm). Visual inspection determined that the black interface layer formed within 2 mo of cattle stocking at all three sites.

  17. 17 CFR 240.0-10 - Small entities under the Securities Exchange Act for purposes of the Regulatory Flexibility Act.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... purposes of a particular rulemaking proceeding, the term small business or small organization shall: (a... “issuer” or “person” that, on the last day of its most recent fiscal year, had total assets of $5 million... the meaning ascribed to those terms by § 270.0-10 of this chapter; (c) When used with reference to...

  18. Soil physical and hydrological properties under three biofuel crops in Ohio

    SciTech Connect

    Bonin, Catherine; Lal, Dr. Rattan; Schmitz, Matthias

    2012-01-01

    While biofuel crops are widely studied and compared for their energy and carbon footprints, less is known about their effects on other soil properties, particularly hydrologic characteristics. Soils under three biofuel crops, corn (Zea mays), switchgrass (Panicum virgatum), and willow (Salix spp.), were analyzed seven years after establishment to assess the effects on soil bulk density ({rho}{sub b}), penetration resistance (PR), water-holding capacity, and infiltration characteristics. The PR was the highest under corn, along with the lowest associated water content, while PR was 50-60% lower under switchgrass. In accordance with PR data, surface (0-10 cm) bulk density also tended to be lower under switchgrass. Both water infiltration rates and cumulative infiltration amounts varied widely among and within the three crops. Because the Philip model did not fit the data, results were analyzed using the Kostiakov model instead. Switchgrass plots had an average cumulative infiltration of 69 cm over 3 hours with a constant infiltration rate of 0.28 cm min{sup -1}, compared with 37 cm and 0.11 cm min{sup -1} for corn, and 26 cm and 0.06 cm min{sup -1} for willow, respectively. Results suggest that significant changes in soil physical and hydrologic properties may require more time to develop. Soils under switchgrass may have lower surface bulk density, higher field water capacity, and a more rapid water infiltration rate than those under corn or willow.

  19. Catalytic behaviour and copper leaching of Cu0.10Zn0.90Al1.90Fe0.10O4 spinel for catalytic wet air oxidation of phenol.

    PubMed

    Xu, Aihua; Sun, Chenglin

    2012-06-01

    A Cu0.10Zn0.90Al1.90Fe0.10O4 spinel catalyst prepared by the sol-gel method was tested for catalytic wet air oxidation (CWAO) of phenol. The catalyst showed high activity for phenol degradation. During successive test at 170 degrees C, 100% phenol conversion and 95% chemical oxygen demand (COD) removal were observed. Results from scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) indicated that the catalyst structure remained unchanged during reaction. From the analysis of temperature programmed reduction (TPR), diffuse reflectance UV-Vis spectra (DR UV-Vis) and activity assay at basic solution pH, it can be suggested that the highly dispersed copper ions on the catalyst surface were almost completely dissolved into the reaction solution, whereas the tetra-coordinated copper ions were not only stable against leaching but also active towards phenol degradation.

  20. Photoluminescence properties of Y0.75-xGdxAl0.10BO3:Eu3+0.10, 0.05R3+ (R = Sc, Bi) (0.00 <= x <= 0.45)

    NASA Astrophysics Data System (ADS)

    Li, Jie; Wang, Yu-Hua; Dong, Qi-Zheng; Liu, Ji-Di

    2010-06-01

    Y0.75-xGdxAl0.10BO3:Eu3+0.10, 0.05R3+ (R = Sc, Bi) (0.00 <= x <= 0.45) powder samples are prepared by solid-state reaction and their luminescence properties are investigated. With the replacement of Y3+ ions by Sc3+ (or Bi3+) and Gd3+ ions in (Y,Al)BO3:Eu, the intensities of emission at 254 and 147 nm are remarkably improved, because Sc3+ ions can absorb UV light and transfer the energy to Eu3+ ions efficiently. Moreover, Gd3+ and Bi3+ ions act as an intermediate “bridge" between the sensitizer and the activator (Eu3+) in energy transfer to produce light in the (Y, Gd)BO3:Bi3+, Eu3+ system more effectively. After doping an appropriate concentration of Gd3+ into Y0.50Gd0.25Al0.10BO3:Eu3+0.01, Bi3+0.05, the emission intensity reaches its maximum, which is nearly 110% compared with the red commercial phosphor (Y,Gd)BO3:Eu and better chromaticity coordinates (0.650, 0.350) are obtained.

  1. Floodplain biogeochemical mosaics: A multidimensional view of alluvial soils

    NASA Astrophysics Data System (ADS)

    Appling, Alison P.; Bernhardt, Emily S.; Stanford, Jack A.

    2014-08-01

    The alluvial floodplains of large rivers are exceptionally productive and dynamic ecosystems, characterized by a complex mosaic of vegetation at different successional stages overlying soils sorted by historic floods. Natural floodplains are widely credited with efficiently removing nitrogen from surface waters and accumulating carbon in biomass, yet very little floodplain research has examined carbon and nitrogen cycling below surficial soils. We evaluated the extent to which vegetation cover could be used to predict subsurface carbon and nitrogen dynamics and to estimate whole-floodplain carbon storage and denitrification rates. We dug soil pits under three dominant vegetation communities on a gravel-bedded floodplain in northwest Montana to the depth of the permanent water table (1-3 m). We compared depth profiles of total and dissolved carbon (C) and nitrogen (N), denitrification potentials (DEAs), organic particulates, moisture, and pH across vegetation types. Near-surface soils (0-10 cm) of forests had larger C and N pools and DEAs than grasslands or gravel bars, but such vegetation effects dissipated within the upper ~50 cm of soil. At depth, spatial heterogeneity in carbon and nitrogen pools and fluxes depended instead on soil texture, and relatively high rates of DEA and carbon storage were measured in zones of buried organic debris. Although C storage and denitrification potential are generally low in subsurface soils, these deep soils might nonetheless contribute substantially to whole-floodplain C storage and denitrification because of their large volume, high hydrologic connectivity, and heterogeneous biogeochemistry.

  2. Leaf nitrogen and phosphorus of temperate desert plants in response to climate and soil nutrient availability.

    PubMed

    He, Mingzhu; Dijkstra, Feike A; Zhang, Ke; Li, Xinrong; Tan, Huijuan; Gao, Yanhong; Li, Gang

    2014-11-06

    In desert ecosystems, plant growth and nutrient uptake are restricted by availability of soil nitrogen (N) and phosphorus (P). The effects of both climate and soil nutrient conditions on N and P concentrations among desert plant life forms (annual, perennial and shrub) remain unclear. We assessed leaf N and P levels of 54 desert plants and measured the corresponding soil N and P in shallow (0-10cm), middle (10-40 cm) and deep soil layers (40-100 cm), at 52 sites in a temperate desert of northwest China. Leaf P and N:P ratios varied markedly among life forms. Leaf P was higher in annuals and perennials than in shrubs. Leaf N and P showed a negative relationship with mean annual temperature (MAT) and no relationship with mean annual precipitation (MAP), but a positive relationship with soil P. Leaf P of shrubs was positively related to soil P in the deep soil. Our study indicated that leaf N and P across the three life forms were influenced by soil P. Deep-rooted plants may enhance the availability of P in the surface soil facilitating growth of shallow-rooted life forms in this N and P limited system, but further research is warranted on this aspect.

  3. [Impact of different tillage practices on soil organic carbon and water use efficiency under continuous wheat-maize binary cropping system].

    PubMed

    Ji, Qiang; Sun, Han-Yin; Taraqqi, A K; Wang, Xu-Dong

    2014-04-01

    Base on an 8-year field experiment, the effects of tillage practices coupled with or without straw return on the soil organic carbon (SOC) and water use efficiency (WUE) were investigated in Guanzhong Plain during the growing seasons from 2008 to 2009. The results showed that conservation tillage practices (sub-soiling, SS; rotary tillage, RT; no-till, NT) improved the SOC, WUE and crop yield compared with conventional tillage (CT), among which, SS coupled with straw return had the highest increment, with increase in SOC content of the 0-30 cm soil layer, WUE and crop yield by 19.5%, 16.9% and 20.5%, respectively. The NT practice effectively increased the SOC content of the 0-10 cm soil layer. Conclusively, under the current soil and climatic conditions in Guanzhong Plain, sub-soiling coupled with straw return is the most efficient tillage practice for promoting SOC accumulation, increasing water-use efficiency and yield.

  4. Study I: effects of 0.06% and 0.10% blood alcohol concentration on human postural control.

    PubMed

    Modig, F; Patel, M; Magnusson, M; Fransson, P A

    2012-03-01

    Alcohol intoxication causes many accidental falls presented at emergency departments, with the injury severity often related to level of blood alcohol concentration (BAC). One way to evaluate the decline in postural control and the fall risk is to assess standing stability when challenged. The study objective was to comprehensively investigate alcohol-related impairments on postural control and adaptive motor learning at specific BAC levels. Effects of alcohol intoxication at 0.06% and 0.10% BAC were examined with posturography when unperturbed or perturbed by calf vibration. Twenty-five participants (mean age 25.1 years) were investigated standing with either eyes open or closed. Our results revealed several significant findings: (1) stability declined much faster from alcohol intoxication between 0.06% and 0.10% BAC (60-140%) compared with between 0.0% and 0.06% BAC (30%); (2) sustained exposure to repeated balance perturbations augmented the alcohol-related destabilization; (3) there were stronger effects of alcohol intoxication on stability in lateral direction than in anteroposterior direction; and (4) there was a gradual degradation of postural control particularly in lateral direction when the balance perturbations were repeated at 0.06% and 0.10% BAC, indicating adaptation deficits when intoxicated. To summarize, alcohol has profound deteriorating effects on human postural control, which are dose dependent, time dependent and direction specific. The maximal effects of alcohol intoxication on physiological performance might not be evident initially, but may be revealed first when under sustained sensory-motor challenges.

  5. Soil organic phosphorus in soils under different land use systems in northeast Germany

    NASA Astrophysics Data System (ADS)

    Slazak, Anna; Freese, Dirk; Hüttl, Reinhard F.

    2010-05-01

    Phosphorus (P) is commonly known as a major plant nutrient, which can act as a limiting factor for plant growth in many ecosystems, including different land use systems. Organic P (Po), transformations in soil are important in determining the overall biological availability of P and additionally Po depletion is caused by land cultivation. It is expected that changes of land use modifies the distribution of soil P among the various P-pools (Ptotal, Plabile, Po), where the Plabile forms are considered to be readily available to plants and Po plays an important role with P nutrition supply for plants. The aim of the study was to measure the different soil P pools under different land use systems. The study was carried out in northeast of Brandenburg in Germany. Different land use systems were studied: i) different in age pine-oak mixed forest stands, ii) silvopastoral land, iii) arable lands. Samples were taken from two mineral soil layers: 0-10 and 10-20 cm. Recently, a variety of analytical methods are available to determine specific Po compounds in soils. The different P forms in the soil were obtained by a sequential P fractionation by using acid and alkaline extractants, which mean that single samples were subjected to increasingly stronger extractants, consequently separating the soil P into fractions based on P solubility. The soil Ptotal for the forest stands ranged from 100 to 183 mg kg -1 whereas Po from 77 to 148 mg kg -1. The Po and Plabile in both soil layers increased significantly with increase of age-old oak trees. The most available-P fraction was Plabile predominate in the oldest pine-oak forest stand, accounting for 29% of soil Ptotal. For the silvopasture and arable study sites the Ptotal content was comparable. However, the highest value of Ptotal was measured in the 30 years old silvopastoral system with 685 mg kg-1 and 728 mg kg-1 at 0-10 cm and 10-20 cm depth, respectively than in arable lands. The results have shown that the 30 years old

  6. Effect of land use on microbial biomass and enzyme activities in tropical soil

    NASA Astrophysics Data System (ADS)

    Maharjan, Menuka; Sanaullah, Muhammad; Kuzyakov, Yakov

    2016-04-01

    Land use change especially from forest to intensive agriculture for sustaining livelihood causing severe consequence on soil quality. Soil microbial biomass and enzyme activities are very sensitive to change in environment. The objective was to assess effects of three land uses i.e. forest, organic and conventional farming on microbial biomass C and N and enzymes involved in C-cycle (β-glucosidase), N-cycle (leucine-aminopeptidase), P-cycle (Phosphatase) and S-cycle (Sulphatase) at different depth (0-100 cm with 10 cm in interval) of soil in Chitwan, Nepal. The result showed that both carbon and nitrogen content (%) was significantly higher in organic farming than conventional farming and forest. However, the trend decreased in lower depth. Significantly high microbial biomass C and N (μg C and N g-1 soil) were found in organic farming than conventional farming and forest at 0-10 cm but the trend was inconsistent in lower depth. β-glucosidase, leucine-aminopeptidase and sulphatase (nmol g-1 soil) activities were higher in organic and conventional farming compared to forest at 0-20 cm. Phosphatase activity was higher in conventional farming than forest and organic farming at 0-20cm. The activities were inconsistent below 20 cm. Application of farmyard manure and organic matter from the vegetation contributes the higher microbial biomass and enzyme activities in organic farming.

  7. Organic and inorganic carbon in paddy soil as evaluated by mid-infrared photoacoustic spectroscopy.

    PubMed

    Changwen, Du; Jianmin, Zhou; Goyne, Keith W

    2012-01-01

    Paddy soils are classified as wetlands which play a vital role in climatic change and food production. Soil carbon (C), especially soil organic C (SOC), in paddy soils has been received considerable attention as of recent. However, considerably less attention has been given to soil inorganic carbon (SIC) in paddy soils and the relationship between SOC and SIC at interface between soil and the atmosphere. The objective of this research was to investigate the utility of applying Fourier transform mid-infrared photoacoustic spectroscopy (FTIR-PAS) to explore SOC and SIC present near the surface (0-10 µm) of paddy soils. The FTIR-PAS spectra revealed an unique absorption region in the wavenumber range of 1,350-1,500 cm(-1) that was dominated by C-O (carbonate) and C-H bending vibrations (organic materials), and these vibrations were used to represented SIC and SOC, respectively. A circular distribution between SIC and SOC on the surface of paddy soils was determined using principal component analysis (PCA), and the distribution showed no significant relationship with the age of paddy soil. However, SIC and SOC were negatively correlated, and higher SIC content was observed near the soil surface. This relationship suggests that SIC in soil surface plays important roles in the soil C dynamics.

  8. Climate response of the soil nitrogen cycle in three forest types of a headwater Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Lupon, Anna; Gerber, Stefan; Sabater, Francesc; Bernal, Susana

    2015-05-01

    Future changes in climate may affect soil nitrogen (N) transformations, and consequently, plant nutrition and N losses from terrestrial to stream ecosystems. We investigated the response of soil N cycling to changes in soil moisture, soil temperature, and precipitation across three Mediterranean forest types (evergreen oak, beech, and riparian) by fusing a simple process-based model (which included climate modifiers for key soil N processes) with measurements of soil organic N content, mineralization, nitrification, and concentration of ammonium and nitrate. The model describes sources (atmospheric deposition and net N mineralization) and sinks (plant uptake and hydrological losses) of inorganic N from and to the 0-10 cm soil pool as well as net nitrification. For the three forest types, the model successfully recreated the magnitude and temporal pattern of soil N processes and N concentrations (Nash-Sutcliffe coefficient = 0.49-0.96). Changes in soil water availability drove net N mineralization and net nitrification at the oak and beech forests, while temperature and precipitation were the strongest climatic factors for riparian soil N processes. In most cases, net N mineralization and net nitrification showed a different sensitivity to climatic drivers (temperature, soil moisture, and precipitation). Our model suggests that future climate change may have a minimal effect on the soil N cycle of these forests (<10% change in mean annual rates) because positive warming and negative drying effects on the soil N cycle may counterbalance each other.

  9. [Spatial pattern of soil moisture at the cropland-grassland boundary in agro-pastoral transitional zone of North China].

    PubMed

    Wang, Hong-Mei; Wang, Kun; Mi, Jia; Xie, Ying-Zhong

    2010-03-01

    By the methods of classic statistics and geostatistics, this paper analyzed the spatial heterogeneity of soil moisture at 0-50 cm depth in different sampling grain sizes (1 m x 1 m and 2 m x 2 m) at the cropland-grassland boundary in agro-pastoral transitional zone of North China. In study area, the soil moisture at 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and 40-50 cm depths of cropland, grassland, and cropland-grassland boundary presented moderate variance, and the coefficient of variation (CV) of grassland was higher than that of cropland. The CV increased with soil depth, and a significant linear regression relation (P < 0.05) was observed between them in sampling grain size 1 m x 1 m. In sampling grain size 1 m x 1 m, the spatial heterogeneity of soil moisture at different depths was obviously higher at cropland-grassland boundary than in cropland and grassland, which had a moderate to strong spatial dependency, and the range (A0) was 7.65-30.99 m; whereas in sampling grain size 2 m x 2 m, the spatial distribution of soil moisture at cropland-grassland boundary had both the moderate to strong spatial dependency and the pure nugget effect, and the A0 was 4.16-18.86 m, suggesting that there existed ecological edge effect of soil moisture at cropland-grassland boundary.

  10. [Effects of the different land use on soil labile organic matter and carbon management index in Junyun Mountain].

    PubMed

    Xu, Peng; Jiang, Chang-Sheng; Hao, Qing-Ju; Zhu, Tao

    2013-10-01

    The impacts of different land use on soil organic matter (SOM), soil labile organic matter (SLOM) and their efficiency ratios (ER), and soil carbon management index (CMI) were studied in this study. Subtropical evergreen broad-leaved forest (abbreviation: forest) , sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm were sampled in the spring of 2011 to determine the contents of soil organic matter and labile organic matter. The results showed that the contents of soil organic matter and soil labile organic matter both decreased with the increase of soil depth under all four land use types; however, forest and orchard enriched SOM and SLOM contents in the 0-10 cm and 0-20 cm soil layers, respectively, while the contents of SOM and SLOM decreased evenly in sloping farmland and abandoned land. In the whole soil layer (0-60 cm) , the order of SOM and SLOM contents was abandoned land > forest > orchard > sloping farmland, indicating that at the conversion from forest into orchard or sloping farmland, SOM was reduced by 21.56% (P >0.05) and 55.90% (P <0.05), respectively, and at the conversion from sloping farmland into abandoned land, the low SLOM, middle SLOM and high SLOM increased by 144.2% (P<0.05) , 153.3% (P <0.05) and 242.7% (P <0.05), respectively. There was no significant difference in low ER, middle ER and high ER among the four land uses as suggested by ANOVA which showed that SRs were not sensible to the change of land use. All three CMis were in the order of abandoned land > forest > orchard > sloping farmland, revealing that forest reclamation resulted in the reduction of soil organic carbon storage and the decline of soil quality, and the abandonment of sloping farmland would increase soil carbon sink and improve soil quality. Three kinds of SLOM were all positively correlated with soil total nitrogen, available phosphorus and available potassium, while negatively correlated

  11. Simulation of Soil Water Content Variability in a Heavy Clay Soil under Contrasting Soil Managements

    NASA Astrophysics Data System (ADS)

    Pedrera, A.; Vanderlinden, K.; Martínez, G.; Espejo, A. J.; Giráldez, J. V.

    2012-04-01

    Soil water content (SWC) is a key variable for numerous physical, chemical and biological processes that take place at or near the soil surface. Understanding the spatial and temporal variability of SWC at the field scale is of prime importance for implementing efficient measurement strategies in applications. The aim of this study was to characterize the spatial and temporal variation of gravimetric SWC in a heavy clay soil, in a wheat-sunflower-legume rotation under conventional (CT) and no-till (NT) using a simple water balance model. An experimental field in SW Spain, where conventional (CT) and no-till (NT) management of a heavy clay soil are being compared since 1983, was sampled for gravimetric SWC on 38 occasions during 2008 and 2009. Topsoil clay content across the six plots was on average 55%, with a standard deviation of 2.7%. The soil profile was sampled at 54 locations, evenly distributed over the three CT and NT plots, at depths of 0-10, 25-35, and 55-65 cm. Topsoil water retention curves (SWRC) were determined in the laboratory on undisturbed soil samples from each of the 54 locations. A weather station recorded daily precipitation and evapotranspiration, as calculated by the Penman-Monteith FAO equation. The water balance was calculated using the Thornthwaite-Mather model with a daily time step. Three parameters, water holding capacity, and water evaporation corrector coefficients for each of the two years, were inversely estimated at the 54 SWC observation points and probability density functions were identified. Spatial variability of SWC was estimated using a Monte Carlo approach, and simulated and observed variability were compared. This Monte Carlo scheme, using a simple water balance model with only three parameters, was found to be useful for evaluating the influence of soil management on the variability of SWC in heavy clay soils.

  12. The Effects of Different Tillage Systems on Soil Hydrology and Erosion in Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Bertolino, A. V. F. A.; Fernandes, N. F.; Souza, A. P.; Miranda, J. P.; Rocha, M. L.

    2009-04-01

    plot. Based on previous studies in this area, suggesting that the plough pan develop at about 20cm depth, the soil water potential (SWP) sensors were installed, in each nest, at 15, 30 and 80 cm depths. Continuously readings in the 30 SWP sensors were made both at a daily and event basis (during some rainfall events) for 25 months. Rainfall was continuously measured in the area by an automatic rain-gauge (tipping bucket) installed close to the plots. In order to characterize changes is soil porosity, both total pore space and pore inter-connections, undisturbed soil blocks were collected for micromorphological analyses (0-10cm, 12-22cm and 25-35cm depths) at small trenches located at the upper parts of each plot. The results attested that soil under CT developed a plough pan layer at about 20 cm depth, showing a 44% decrease in total pore space from 0-10cm to 12-22cm depths, with a predominant network of isolated pores. In the MT plot, soil porosity is more homogeneous with depth, with a predominant network of larger and better connected pores. The results related to soil hydrology show that in many moments, both CT and MT, stay very close to saturation, both at 15 and 30 cm depth. Above the plough pan under CT, soils tend to saturate faster and to have a slower drainage rate than the ones under MT. Detailed SWP analyses made during rain events suggest that CT may favors lateral flows while soils under MT are draining. Soil erosion rates measured for individual events at CT are about four times greater than the ones observed at MT. The results observed in this study attest that conventional tillage (CT) in this area imposed important changes in soil structure, pore-size distribution and connectivity, as well as in soil infiltration, drainage and erosion.

  13. Miscanthus-derived SOC: numerically declining over soil depths

    NASA Astrophysics Data System (ADS)

    Hu, Yaxian; Schäfer, Gerhard; Duplay, Joëlle; Kuhn, Nikolaus J.

    2016-04-01

    Miscanthus is one of the most efficient perennial bioenergy crops for wide establishment and distribution. Most of the previous reports had shown the benefits of Miscanthus cultivation in soil organic carbon (SOC) sequestration and greenhouse gas emissions (GHG) mitigation. However, some other papers pointed out that the Miscanthus-derived SOC is mainly of particulate organic matter and the labile quality of particulate organic matter may bear great uncertainties in GHGs emissions. This urges the necessity to investigate the quality and mineralization potential of Miscanthus-derived SOC. This study investigated soil profiles deep to 1 m from 20 yr Miscanthus fields in France and Switzerland. Soil organic carbon (SOC) concentration and δ13C compositions of all the soil layers (0-10, 10-40, 40-70 and 70-100 cm) were determined. Our results show that: 1) Miscanthus cultivation can in general increase the SOC stocks compared to the Grassland, while the benefits of SOC sequestration may only constrain to the surface soil. Isotopically, the Miscanthus-derived SOC ranged from 69% the top 10 cm soil down to only 7% in the 70 to 100 cm layer, cautioning the use of SOC stocks on the surface soil to estimate the total net benefits of Miscanthus cultivation in terms of sequestrating atmospheric CO2. 2) Compared to the Grassland soils, the surface soils on the Miscanthus fields tended to have a risk of acidification (pH values down to 6) and exceeded contents of P and K, adding another precaution to the environmental impacts of Miscanthus cultivation in the entire Upper Rhine Region. Overall, changes of soil characteristics must be included into Life Cycle Assessment to fully evaluate the environmental impacts of long-term Miscanthus cultivation.

  14. Assessing Impacts of 20 yr Old Miscanthus on Soil Organic Carbon Quality

    NASA Astrophysics Data System (ADS)

    Hu, Yaxian; Schäfer, Gerhard; Kuhn, Nikolaus

    2015-04-01

    The use of biomass as a renewable energy source has become increasingly popular in Upper Rhine Region to meet the demand for renewable energy. Miscanthus is one of the most favorite biofuel crops, due to its long life and large yields, as well as low energy and fertilizer inputs. However, current research on Miscanthus is mostly focused on the techniques and economics to produce biofuel or the impacts of side products such as ash and sulfur emissions to human health. Research on the potential impacts of Miscanthus onto soil quality, especially carbon quality after long-term adoption, is very limited. Some positive benefits, such as sequestrating organic carbon, have been repeatedly reported in previous research. Yet the quality of newly sequestrated organic carbon and its potential impacts onto global carbon cycling remain unclear. To fully account for the risks and benefits of Miscanthus, it is required to investigate the quality as well as the potential CO2 emissions of soil organic carbon on Miscanthus fields. As a part of the Interreg Project to assess the environmental impacts of biomass production in the Upper Rhine Region, this study aims to evaluate the carbon quality and the potential CO2 emissions after long-term Miscanthus adoption. Soils were sampled at 0-10, 10-40, 40-70, and 70-100 cm depths on three Miscanthus fields with up to 20 years of cultivation in Ammerzwiller France, Münchenstein Switzerland, and Farnsburg Switzerland. Soil texture, pH, organic carbon and nitrogen content were measured for each sampled layer. Topsoils of 0-10 cm and subsoils of 10-40 cm were also incubated for 40 days to determine the mineralization potential of the soil organic matter. Our results show that: 1) only in top soils of 0-10 cm, the 20 year old Miscanthus field has significantly higher soil organic carbon concentrations, than the control site. No significant differences were observed in deeper soil layers. Similar tendencies were also observed for organic

  15. Rock fragments induce patchy distribution of soil water repellency in burned soils

    NASA Astrophysics Data System (ADS)

    Gordillo-Rivero, Ángel; García-Moreno, Jorge; Bárcenas-Moreno, Gema; Jiménez-Morillo, Nicasio T.; Mataix-Solera, Jorge; Jordán, Antonio; Zavala, Lorena M.

    2013-04-01

    %). Soil WR was assessed in soil samples (0-10 cm) collected monthly during 6 monhts after burning. In the second case, a fire-affected forest soil from Calañas (Huelva, southweastern Spain) was studied. Soil plots under different fire severities (low, medium and high severity burning) and rock fragment cover classes (20-40 and 60-80%) were analyzed. Soil WR was assessed in the soil surface immediately under the vertical projection of randomly selected stones and in the middle point between these and the nearest stones. Unburned adjacent soils under similar rock fragment cover classes were used as control. All soil WR assessments were carried out using the WDPT method. RESULTS In both cases, soil WR was induced in the soil surface contacting rock fragments after burning. Severity of WR ranged between subcritical or slight (low severity burning) and strong (high severity burning). Soil WR was also found to increase with rock fragment cover, especially after moderate or high severity burning, both under and between rock fragments. It is suggested that high density of rock fragments on the soil surface create a continuous surface of high residence of temperature peaks (in agreement with García-Moreno et al., 2013). Combustion of plant residues in oxygen depletion conditions between adjacent nearby rock fragments contributes to heat transfer to the soil surface and consequent enhanced soil WR. REFERENCES García-Moreno, J., Gordillo-Rivero, A.J., Gil, J., Jiménez-Morillo, N.T., Mataix-Solera, J., González-Peñaloza, F.A., Granged, A.J.P., Bárcenas-Moreno, G., Jiménez-Pinilla, P., Lozano, E., Jordán, A., Zavala, L.M. 2013. Do stones modify the spatial distribution of fire-induced soil water repellency? Preliminary data. Flamma, 4:76-80.

  16. 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...

  17. 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

  18. [Vertical distribution patterns of nitrogen, phosphorus, and potassium in Chinese pine forest soils developed from different parent materials in Songshan Mountain Nature Reserve, Beijing of China].

    PubMed

    Gou, Li-hui; Sun, Zhao-di; Nie, Li-shui; Luo, Pan-pan; Wu, Ji-Gui; Xu, Wu-de

    2013-04-01

    Taking the soils developed from two kinds of parent materials (granite and limestone) under Pinus tabulaeformis forest at the same altitude in Songshan Mountain Nature Reserve of Beijing as test objects, this paper studied the vertical distribution patterns of soil total nitrogen, available phosphorus, and available potassium. The soil developed from granite had the total nitrogen, available phosphorus, and available potassium contents being 1.61-2. 35 g kg-1, 5. 84-10.74 mg kg- 1, and 39.33-93.66 mg kg-1, while that developed from limestone had the total nitrogen, available phosphorus, and available potassium contents being 1. 69 -2. 36 g kg-1, 4.45-8.57 mg . kg-1, and 60.66-124.00 mg kg-1, respectively. The total nitrogen, available phosphorus, and available potassium contents in the two soils were the highest in 0-10 cm layer, decreased with increasing depth, and had significant differences between different layers, showing that the soil total nitrogen, available phosphorus, and available potassium had a strong tendency to accumulate in surface layer. Such a tendency was more obvious for the soil developed from limestone. The paired t-test for the two soils indicated that the total nitrogen content in different layers had no significant difference, whereas the available phosphorus content in 0-10 cm layer and the available potassium content in 10-20 cm layer differed significantly.

  19. [Effects of different straw recycling and tillage methods on soil respiration and microbial activity].

    PubMed

    Li, Xiao-sha; Wu, Ning; Liu, Ling; Feng, Yu-peng; Xu, Xu; Han, Hui-fang; Ning, Tang-yuan; Li, Zeng-jia

    2015-06-01

    To explore the effects of different tillage methods and straw recycling on soil respiration and microbial activity in summer maize field during the winter wheat and summer maize double cropping system, substrate induced respiration method and CO2 release method were used to determine soil microbial biomass carbon, microbial activity, soil respiration, and microbial respiratory quotient. The experiment included 3 tillage methods during the winter wheat growing season, i.e., no-tillage, subsoiling and conventional tillage. Each tillage method was companied with 2 straw management patterns, i.e., straw recycling and no straw. The results indicated that the conservation tillage methods and straw recycling mainly affected 0-10 cm soil layer. Straw recycling could significantly improve the microbial biomass carbon and microbial activity, while decrease microbial respiratory quotient. Straw recycling could improve the soil respiration at both seedling stage and anthesis, however, it could reduce the soil respiration at filling stage, wax ripeness, and harvest stage. Under the same straw application, compared with conventional tillage, the soil respiration and microbial respiratory quotient in both subsoiling and no-tillage were reduced, while the microbial biomass carbon and microbial activity were increased. During the summer maize growing season, soil microbial biomass carbon and microbial activity were increased in straw returning with conservation tillage, while the respiratory quotient was reduced. In 0-10 cm soil layer, compared with conventional tillage, straw recycling with subsoiling and no-tillage significantly increased soil microbial biomass carbon by 95.8% and 74.3%, and increased soil microbial activity by 97.1% and 74.2%, respectively.

  20. 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.

  1. Effect of forest and soil type on microbial biomass carbon and respiration

    NASA Astrophysics Data System (ADS)

    Habashi, Hashem

    2016-09-01

    The aim of study was to evaluate the variation of soil microbial biomass carbon (Cmic) and microbial respiration (MR) in three types soil (Chromic Cambisols, Chromic Luvisols and Eutric Leptosols) of mixed beech forest (Beech- Hornbeam and Beech- Maple). Soil was randomly sampled from 0-10 cm layer (plant litter removed), 90 soil samples were taken. Cmic determined by the fumigation-extraction method and MR by closed bottle method. Soil Corg, Ntot and pH were measured. There are significant differences between the soil types concerning the Cmic content and MR. These parameters were highest in Chromic Cambisols following Chromic Luvisols, while the lowest were in Eutric Leptosols. A similar trend of Corg and Ntot was observed in studied soils. Two-way ANOVA indicated that soil type and forest type have significantly effect on the most soil characteristics. Chromic Cambisols shows a productive soil due to have the maximum Cmic, MR, Corg and Ntot. In Cambisols under Beech- Maple forest the Cmic value and soil C/N ratio were higher compared to Beech-Hornbeam (19.5 and 4.1 mg C g-1, and 16.3 and 3.3, respectively). This fact might be indicated that Maple litter had more easy decomposable organic compounds than Hornbeam. According to regression analysis, 89 and 68 percentage of Cmic variability could explain by soil Corg and Ntot respectively.

  2. [Heavy Metals Accmultio in the Caofeidian Reclamation Soils: Indicated by Soil Magnetic Susceptibility].

    PubMed

    Xue, Yong; Zhou, Qian; Li, Yuan; Zhang, Hai-bo; Hu, Xue-feng; Luo, Yong-ming

    2016-04-15

    The environmental magnetism method has been widely applied to identify soil heavy metal pollution, which is characterized by simplicity, efficiency, non-destructivity and sensitivity. The present study used magnetic susceptibility to assess the accumulation of heavy metals in soils of the Caofeidian industrial zone which is a typical reclamation area in northern China. The study area was divided into three sub-zones based on the function, including industrial zone, living zone, natural tidal flat and wetland. A total of 35 topsoil samples (0-10 cm) and 3 soil profiles were collected from the three sub-zones. Magnetic susceptibility (X(lf)), iron oxide (Fe2O3) contents and heavy metals contents (Cr, Ni, Cu, Zn, As, Pb, Mn and V) of the samples were analyzed. The results showed that X(lf) values and heavy metals contents exhibited higher spatial variability in the top soil of the industrial zone, indicating the severe impacts of industrial activities. In the soil profiles of the industrial and living zones, all heavy metals were enriched to different degrees in the upper layer (0-20 cm). However, there was no significant change of heavy metal contents in the soil profiles of tidal flat which was far from the industrial area. The X(lf) value was significantly (P < 0.01) positively correlated with the contents of Fe2O3, Ni, Cu, As and V in the industrial top soil. This indicated that X(lf) could be used as an indicator for heavy metal accumulation in the industrial zone. However, the X(lf) value was not suitable to be an indicator to show the heavy metal accumulation in the soils of living zone and natural tidal flat. This might be associated with the different sources of magnetic materials among the different sub-zones and the special characteristics of the soils in the tidal flat and wetland.

  3. Preparation of UC0.07-0.10N0.90-0.93 spheres for TRISO coated fuel particles

    SciTech Connect

    Collins, Jack Lee; Hunt, Rodney Dale; Johnson, Jared A; Silva, Chinthaka M; Lindemer, Terrence

    2014-01-01

    The U.S. Department of Energy is considering a new nuclear fuel, which should be much more impervious during a loss of coolant accident. The fuel would consist of tristructural isotropic coated particles with dense uranium nitride (UN) kernels. The objectives of this effort are to make uranium oxide microspheres with adequately dispersed carbon nanoparticles and to convert these microspheres into UN kernels. Recent improvements to internal gelation process were successfully applied to the production of uranium gel spheres with different concentrations of carbon black. After the spheres were washed, a simple, two-step heat profile was used to produce kernels with a chemical composition of UC0.07 0.10N0.90 0.93. The first step involved heating the microspheres to 2023 K in a vacuum, and in the second step, the microspheres were held at 1873 K for 6 hrs in nitrogen.

  4. Changes to soil bacterial profiles as a result of Sus scrofa domesticus decomposition.

    PubMed

    Olakanye, Ayodeji O; Thompson, Tim; Komang Ralebitso-Senior, T

    2014-12-01

    The importance of cadaver decomposition knowledge for clandestine grave location cannot be over emphasised. Notwithstanding this, only a limited understanding is available on the resulting soil microbial community dynamics. To address this paucity, a pig leg (Sus scrofa domesticus; 5kg) was buried in freshly weighed (20kg) sandy loamy soil in a sealed microcosm (40cm height) in parallel with a soil only control. Both microcosms were perforated nine times at equal distances and maintained outside. Soil samples were collected through these perforations from the top (0-10cm), middle (10-20cm) and bottom (20-30cm) segments every three days for the first two weeks, and then weekly up to 14 weeks. PCR-DGGE gels quantified by 1D Phoretix showed increases in the cumulative soil community richness values of 43, 66 and 106 for the top, middle and bottom segments, respectively, in the presence of Sus scrofa domesticus. Shannon-Wiener's (H') and Simpon's (D) indices confirmed corresponding species diversity increases in the middle (H'=1.58-2.33; D=0.79-0.91) and bottom (H'=2.48-3.16; D=0.85-0.95) depths between days 10 and 71 compared with the control. In contrast, similar evenness was recorded for all segments in both the Sus scrofa domesticus and control soils.

  5. Linking hydraulic properties of fire-affected soils to infiltration and water repellency

    USGS Publications Warehouse

    Moody, J.A.; Kinner, D.A.; Ubeda, X.

    2009-01-01

    Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, S(??i), as a function of initial soil moisture content, ??i, ranging from extremely dry conditions (??i < 0.02 cm3 cm-3) to near saturation. In the field and in the laboratory replicate measurements were made of ash, reference soils, soils unaffected by fire, and fire-affected soils. Each has a different degrees of water repellency that influences Kf and S(??i). Values of Kf ranged from 4.5 ?? 10-3 to 53 ?? 10-3 cm s-1 for ash; from 0.93 ?? 10-3 to 130 ?? 10-3 cm s-1 for reference soils; and from 0.86 ?? 10-3 to 3.0 ?? 10-3 cm s-1, for soil unaffected by fire, which had the lowest values of Kf. Measurements indicated that S(??i) could be represented by an empirical non-linear function of ??i with a sorptivity maximum of 0.18-0.20 cm s-0.5, between 0.03 and 0.08 cm3 cm-3. This functional form differs from the monotonically decreasing non-linear functions often used to represent S(??i) for rainfall-runoff modeling. The sorptivity maximum may represent the combined effects of gravity, capillarity, and adsorption in a transitional domain corresponding to extremely dry soil, and moreover, it may explain the observed non-linear behavior, and the critical soil-moisture threshold of water repellent soils. Laboratory measurements of Kf and S(??i) are the first for ash and fire-affected soil, but additional measurements are needed of these hydraulic properties for in situ fire-affected soils. They provide insight into water repellency behavior and infiltration under extremely dry conditions. Most importantly, they indicate how existing rainfall-runoff models can be modified to

  6. Soil Respiration Responses to Variation in Temperature Treatment and Vegetation Type

    NASA Astrophysics Data System (ADS)

    Liu, S.; Pavao-zuckerman, M.

    2013-12-01

    Complex linkages exist between terrestrial vegetation, soil moisture, soil organic matter (SOM), local climate, and soil microorganisms. Thus, large-scale changes in vegetation, such as the woody plant encroachment observed in many historically semiarid and arid grasslands worldwide, could potentially alter the flux of carbon from soil reserves to the atmosphere. Mathematical models that attempt to project the long-term impact of vegetative shifts on soil fluxes largely rely on assumptions such as first-order donor control rather than incorporate the biological aspects of soil respiration such as microbial activity. To examine the impact of vegetation type on soil physicochemical properties and soil microbial respiration and provide experimental data to refine existing predictive models, we compared soil (ground basalt from northern Arizona) in mesocosms established with no vegetation, velvet mesquites (Prosopis velutina; woody shrub), or sideoats gramas (Bouteloua curtipendula; grass) for 2 years, The temperature sensitivity of soil respiration was examined by incubating soil (0-10 and 10-30 cm depth fractions) from each vegetation treatment at 10, 20, 30, and 40 °C for 24 hours. Vegetated soils contained more SOM (~0.1% for mesquite and grass mesocosms) than non-vegetated soils (~0.02%). Respiration rates were generally highest from grass-established soils, intermediate from mesquite-established soils, and lowest from non-vegetated soils. Respiration rates of samples incubated without the addition of substrate peaked at approximately 30 °C, whereas respiration rates of samples incubated with dextrose were highest at 40 °C. Further, the respiration assays suggest that while respiration rates are overall higher in grass-established soils, mesquite-established soils are more temperature sensitive which may have significant implications in the context of global warming and current fire management practices.

  7. Determination of the 243 Cm/244 Cm ratio alpha spectrometry and spectral deconvolution in environmental samples exposed to discharges from the nuclear fuel cycle.

    PubMed

    Mitchell, P I; Holm, E; León Vintró, L; Condren, O M; Roos, P

    1998-01-01

    The presence of curium nuclides in irradiated nuclear fuel is well known, as is their occurrence in environmental materials exposed to liquid waste discharges from reprocessing plants and to fallout following the Chernobyl accident. Knowledge of the 242 Cm/244 Cm and 243 Cm/244 Cm atom ratios can be a useful tool for characterizing a source-term and assessing the burn-up history of nuclear fuel. Here, a practical technique, based on high-resolution alpha spectrometry and spectral deconvolution, is described by which the 243, 244 Cm multiplet can be resolved at the low activities typical of most environmental samples. The resulting 243 Cm/244 Cm ratio is then used to correct for any interference by 243 Cm in the 242 Cm window. The technique has been applied to the determination of the 243 Cm/244 Cm ratio in samples of seabed sediment collected near the Sellafield outfall, riverine sediment sampled downstream of the Mayak reprocessing plant and soil and lichen from within the Chernobyl exclusion zone. Near Sellafield, the 243 Cm/244 Cm ratio was found to be < 2%, while near Mayak and Chernobyl it was considerably higher, being approximately 6-8%.

  8. Persistence of polycyclic aromatic hydrocarbons (PAHs) in biochar-amended soil.

    PubMed

    Kuśmierz, Marcin; Oleszczuk, Patryk; Kraska, Piotr; Pałys, Edward; Andruszczak, Sylwia

    2016-03-01

    In the present study the persistence of polycyclic aromatic hydrocarbons (PAHs) applied with biochar to acidic soil (loamy sand) was studied in two and half year field experiment. An experiment was carried out in three experimental plots (15 m(2) each). The biochar was introduced in the following doses: soil without fertilization - control (C-BC00), soil with 30 t ha(-1) (B-BC30) and soil with 45 t ha(-1) (A-BC45) of biochar. Biochar addition to soils resulted in an increase in the PAHs content from 0.239 μg g(-1) in control soil to 0.526 μg g(-1) and 1.310 μg g(-1) in 30 and 45 t ha(-1) biochar-amended soil respectively. However during the experimental period the PAHs content decreased to a level characteristic for the control soil. The highest losses of PAHs were observed during the first 105 days of the experiment. Three and four rings PAHs were the most susceptible for degradation and leaching. Migration of PAHs from 0-10 cm to 10-20 cm soil horizon was also observed.

  9. Dynamics of soil organic carbon and microbial activity in treated wastewater irrigated agricultural soils along soil profiles

    NASA Astrophysics Data System (ADS)

    Jüschke, Elisabeth; Marschner, Bernd; Chen, Yona; Tarchitzky, Jorge

    2010-05-01

    Treated wastewater (TWW) is an important source for irrigation water in arid and semiarid regions and already serves as an important water source in Jordan, the Palestinian Territories and Israel. Reclaimed water still contains organic matter (OM) and various compounds that may effect microbial activity and soil quality (Feigin et al. 1991). Natural soil organic carbon (SOC) may be altered by interactions between these compounds and the soil microorganisms. This study evaluates the effects of TWW irrigation on the quality, dynamics and microbial transformations of natural SOC. Priming effects (PE) and SOC mineralization were determined to estimate the influence of TWW irrigation on SOC along soil profiles of agricultural soils in Israel and the Westbank. The used soil material derived from three different sampling sites allocated in Israel and The Palestinian Authority. Soil samples were taken always from TWW irrigated sites and control fields from 6 different depths (0-10, 10-20, 20-30, 30-50, 50-70, 70-100 cm). Soil carbon content and microbiological parameters (microbial biomass, microbial activities and enzyme activities) were investigated. In several sites, subsoils (50-160 cm) from TWW irrigated plots were depleted in soil organic matter with the largest differences occurring in sites with the longest TWW irrigation history. Laboratory incubation experiments with additions of 14C-labelled compounds to the soils showed that microbial activity in freshwater irrigated soils was much more stimulated by sugars or amino acids than in TWW irrigated soils. The lack of such "priming effects" (Hamer & Marschner 2005) in the TWW irrigated soils indicates that here the microorganisms are already operating at their optimal metabolic activity due to the continuous substrate inputs with soluble organic compounds from the TWW. The fact that PE are triggered continuously due to TWW irrigation may result in a decrease of SOC over long term irrigation. Already now this could be

  10. Validation of Noah-simulated Soil Temperature in the North American Land Data Assimilation System Phase 2

    SciTech Connect

    Xia, Youlong; Ek, Michael; Sheffield, Justin; Livneh, Ben; Huang, Maoyi; Wei, Helin; Song, Feng; Luo, Lifeng; Meng, Jesse; Wood, Eric

    2013-02-25

    Soil temperature can exhibit considerable memory from weather and climate signals and is among the most important initial conditions in numerical weather and climate models. Consequently, a more accurate long-term land surface soil temperature dataset is needed to improve weather and climate simulation and prediction, and is also important for the simulation of agricultural crop yield and ecological processes. The North-American Land Data Assimilation (NLDAS) Phase 2 (NLDAS-2) has generated 31-years (1979-2009) of simulated hourly soil temperature data with a spatial resolution of 1/8o. This dataset has not been comprehensively evaluated to date. Thus, the ultimate purpose of the present work is to assess Noah-simulated soil temperature for different soil depths and timescales. We used long-term (1979-2001) observed monthly mean soil temperatures from 137 cooperative stations over the United States to evaluate simulated soil temperature for three soil layers (0-10 cm, 10-40 cm, 40-100 cm) for annual and monthly timescales. We used short-term (1997-1999) observed soil temperature from 72 Oklahoma Mesonet stations to validate simulated soil temperatures for three soil layers and for daily and hourly timescales. The results showed that the Noah land surface model (Noah LSM) generally matches observed soil temperature well for different soil layers and timescales. At greater depths, the simulation skill (anomaly correlation) decreased for all time scales. The monthly mean diurnal cycle difference between simulated and observed soil temperature revealed large midnight biases in the cold season due to small downward longwave radiation and issues related to model parameters.

  11. [Impact of land use change and cultivation measures on soil organic carbon (SOC) and its 13C values].

    PubMed

    Meng, Fan-qiao; Kuang, Xing; Du, Zhang-liu; Wu, Wen-liang; Guo, Yan-bin

    2010-08-01

    In Quzhou County, Hebei Province where now intensive farming system is operated, original grassland and farming land under different tillage, crop straw return and fertilization measures were studied using isotope carbon for the analysis of the impact on soil organic carbon (SOC) properties. The research indicated that after change into farmland (34 years), SOC is significantly reduced and for 1 m of soil layer, the scope of reduction is from 13.3%-35% and this decrease happens in 0-40 cm of soil layer. After 8 years of fertilization, SOC can be increased at 0.83 g x kg(-1). No-tillage can significantly increase the SOC especially in 0-10 cm but plough will increase the SOC at 10-15 cm and 15-20 cm. Change of delta13 C of SOC due to land use change mainly happens in 0-20 cm, where input of organic materials from maize stored. In soil layer of 0-5 cm, only maximum 18% of SOC is from crop residues and in 15-20 cm, this percentage is about 5%.

  12. Magnetic phase transition of nanocrystalline Fe-doped samarium oxide (Sm1.90Fe0.10O3)

    NASA Astrophysics Data System (ADS)

    Mandal, J.; Sarkar, B. J.; Deb, A. K.; Chakrabarti, P. K.

    2014-12-01

    Nanocrystalline Fe3+ doped samarium oxide (Sm1.90Fe0.10O3) has been prepared by the co-precipitation method. The as prepared sample has been annealed at 700 °C for 6 h in an argon atmosphere. The pure crystallographic phase as well as the substitution of Fe3+ ions in the lattice of Sm2O3 is confirmed by Rietveld analysis of the X-ray diffraction patterns. The variation of magnetic susceptibility (χ) with temperature (T) is recorded by a Faraday Magnetometer in the temperature range of 300-14 K. The variation of χ vs. T down to ~50 K was successfully fitted by the Curie-Weiss law and below this temperature, susceptibility increases very rapidly, which suggests the presence of ordering at low temperature. To explore this, magnetic measurements are also carried out at different temperatures down to 2 K by using a SQUID Magnetometer. No hysteretic behavior is observed down to 50 K, but a feeble ferromagnetic behavior is observed in the magnetization vs. field curve recorded at ~30 K. A clear hysteresis loop is observed at 2 K with a comparatively high value of maximum magnetization (~3.32 emu/gm). The observed magnetic phase transition is analyzed by using the dipole-dipole interaction among the magnetic nanoparticles at low temperature.

  13. Preparation of UC0.07-0.10N0.90-0.93 spheres for TRISO coated fuel particles

    NASA Astrophysics Data System (ADS)

    Hunt, R. D.; Silva, C. M.; Lindemer, T. B.; Johnson, J. A.; Collins, J. L.

    2014-05-01

    The US Department of Energy is considering a new nuclear fuel that would be less susceptible to ruptures during a loss-of-coolant accident. The fuel would consist of tristructural isotropic coated particles with dense uranium nitride (UN) kernels with diameters of 650 or 800 μm. The objectives of this effort are to make uranium oxide microspheres with adequately dispersed carbon nanoparticles and to convert these microspheres into UN spheres, which could be then sintered into kernels. Recent improvements to the internal gelation process were successfully applied to the production of uranium gel spheres with different concentrations of carbon black. After the spheres were washed and dried, a simple two-step heat profile was used to produce porous microspheres with a chemical composition of UC0.07-0.10N0.90-0.93. The first step involved heating the microspheres to 2023 K in a vacuum, and in the second step, the microspheres were held at 1873 K for 6 h in flowing nitrogen.

  14. [Characteristics of soil denitrifying enzyme activity in riparian zones with different land use types in Chongming Island, Shanghai of China].

    PubMed

    Chen, Gang-Liang; Li, Jian-Hua; Yang, Chang-Ming

    2013-10-01

    By using acetylene inhibition method, this paper studied the soil denitrifying enzyme activity (DEA) and its affecting factors in the riparian zone with different land use types (cropland riparian, forested riparian, and grassy riparian zones) in Chongming Island, Shanghai of China. The riparian soil DEA was (0.69 +/- 0.11)--(134.93 +/- 33.72) microg N x kg(-1) x h(-1), which differed obviously among different land types, with a decreasing trend of forested riparian zone > cropland riparian zone > grassy riparian zone. The soil DEA was significantly (P < 0.05) higher in 0-10 cm in 10-30, 30-50, and 50-70 cm layers. There were significant positive relationships between soil DEA and soil TOC, TN, and NO(3-)-N (P < 0.01). Land use change mainly altered the soil natural structure and soil physical and chemical properties, decreased the accumulation of soil organic carbon, and affected the soil nitrogen transformation, and thus, inhibited the occurrence of riparian soil denitrification.

  15. Parallel processing: The Cm/sup */ experience

    SciTech Connect

    Siewiorek, D.; Gehringer, E.; Segall, Z.

    1986-01-01

    This book describes the parallel-processing research with CM/sup */ at Carnegie-Mellon University. Cm/sup */ is a tightly coupled 50-processor multiprocessing system that has been in operation since 1977. Two complete operating systems-StarOS and Medusa-are part of its development along with a number of applications.

  16. [Effects of grazing disturbance on soil active organic carbon in mountain forest-arid valley ecotone in the upper reaches of Minjiang River].

    PubMed

    Liu, Shan-Shan; Zhang, Xing-Hua; Gong, Yuan-Bo; Li, Yuan; Wang, Yan; Yin, Yan-Jie; Ma, Jin-Song; Guo, Ting

    2014-02-01

    Effects of grazing disturbance on the soil carbon contents and active components in the four vegetations, i.e., artificial Robinia pseudoacacia plantation, artificial poplar plantation, Berberis aggregate shrubland and grassland, were studied in the mountain forest-arid valley ecotone in the upper Minjiang River. Soil organic carbon and active component contents in 0-10 cm soil layer were greater than in 10-20 cm soil layer at each level of grazing disturbance. With increasing the grazing intensity, the total organic carbon (TOC), light fraction organic carbon (LFOC), particulate organic carbon (POC) and easily oxidized carbon (LOC) contents in 0-10 cm soil layer decreased gradually in the artificial R. pseudoacacia plantation. The LFOC content decreased, the POC content increased, and the TOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the artificial poplar plantation. The POC content decreased, and the TOC, LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the B. aggregate shrubland. The POC and TOC contents decreased, and the LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the grassland. The decreasing ranges of LOC, LFOC and POC contents were 0.1-7.9 times more than that of TOC content. There were significant positive relationships between TOC and LOC, LFOC and POC, suggesting that the active organic carbon components could reflect the change of soil total carbon content.

  17. Conductivity and transit time estimates of a soil liner

    USGS Publications Warehouse

    Krapac, I.G.; Cartwright, K.; Panno, S.V.; Hensel, B.R.; Rehfeldt, K.H.; Herzog, B.L.

    1990-01-01

    A field-scale soil linear was built to assess the feasibilty of constructing a liner to meet the saturated hydraulic conductivity requirement of the U.S. EPA (i.e., less than 1 ?? 10-7 cm/s), and to determine the breakthrough and transit times of water and tracers through the liner. The liner, 8 ?? 15 ?? 0.9 m, was constructed in 15-cm compacted lifts using a 20,037-kg pad-foot compactor and standard engineering practices. Estimated saturated hydraulic conductivities were 2.4 ?? 10-9 cm/s, based on data from large-ring infiltrometers; 4.0 ?? 10-8 cm/s from small-ring infiltrometers; and 5.0 ?? 10-8 cm/s from a water-balance analysis. These estimates were derived from 1 year of monitoring water infiltration into the linear. Breakthrough of tracers at the base of the liner was estimated to be between 2 and 13 years, depending on the method of calculation and the assumptions used in the calculation.

  18. Soil nematode communities are ecologically more mature beneath late- than early-successional stage biological soil crusts

    USGS Publications Warehouse

    Darby, B.J.; Neher, D.A.; Belnap, J.

    2007-01-01

    Biological soil crusts are key mediators of carbon and nitrogen inputs for arid land soils and often represent a dominant portion of the soil surface cover in arid lands. Free-living soil nematode communities reflect their environment and have been used as biological indicators of soil condition. In this study, we test the hypothesis that nematode communities are successionally more mature beneath well-developed, late-successional stage crusts than immature, early-successional stage crusts. We identified and enumerated nematodes by genus from beneath early- and late-stage crusts from both the Colorado Plateau, Utah (cool, winter rain desert) and Chihuahuan Desert, New Mexico (hot, summer rain desert) at 0-10 and 10-30 cm depths. As hypothesized, nematode abundance, richness, diversity, and successional maturity were greater beneath well-developed crusts than immature crusts. The mechanism of this aboveground-belowground link between biological soil crusts and nematode community composition is likely the increased food, habitat, nutrient inputs, moisture retention, and/or environmental stability provided by late-successional crusts. Canonical correspondence analysis of nematode genera demonstrated that nematode community composition differed greatly between geographic locations that contrast in temperature, precipitation, and soil texture. We found unique assemblages of genera among combinations of location and crust type that reveal a gap in scientific knowledge regarding empirically derived characterization of dominant nematode genera in deserts soils and their functional role in a crust-associated food web. ?? 2006 Elsevier B.V. All rights reserved.

  19. Stable and radioactive carbon in forest soils of Chhattisgarh, Central India: Implications for tropical soil carbon dynamics and stable carbon isotope evolution

    NASA Astrophysics Data System (ADS)

    Laskar, A. H.; Yadava, M. G.; Ramesh, R.

    2016-06-01

    Soils from two sites viz. Kotumsar and Tirathgarh, located ∼5 km apart in a tropical reserve forest (18°52‧N, 81°56‧E) in central India, have been explored for soil organic carbon (SOC) content, its mean residence time (MRT) and the evolution of stable carbon isotopic composition (δ13C). SOC stocks in the upper 30 cm of soil layers are ∼5.3 kg/m2 and ∼3.0 kg/m2; in the upper 110 m are ∼10.7 kg/m2 and ∼7.8 kg/m2 at Kotumsar and Tirathgarh, respectively. SOC decreases with increasing depth. Bomb carbon signature is observed in the upper ∼10 cm. Organic matters in the top soil layers (0-10 cm) have MRTs of the order of a century which increases gradually with depths, reaching 3500-5000 yrs at ∼100 cm. δ13C values of SOC increase with depth, the carbon isotopic fractionation is obtained to be -1.2‰ and -3‰ for soils at Kotumsar and Tirathgarh, respectively, confirmed using Rayleigh isotopic fractionation model. The evolution of δ13C in soils was also studied using a modified Rayleigh fractionation model incorporating a continuous input into the reservoir: the depth profiles of δ13C for SOC show that the input organic matter from surface into the deeper soil layers is either insignificant or highly labile and decomposes quite fast in the top layers, thus making little contribution to the residual biomasses of the deeper layers. This is an attempt to understand the distillation processes that take place in SOC, assess the extent of decomposition by microbes and effect of percolation of fresh organic matter into dipper soil layers which are important for stable isotope based paleoclimate and paleovegetation reconstruction and understanding the dynamics of organic carbon in soils.

  20. Soil Organic Carbon and Nutrient Dynamics in Reclaimed Appalachian Mine Soil

    NASA Astrophysics Data System (ADS)

    Acton, P.; Fox, J.; Campbell, J. E.; Rowe, H. D.; Jones, A.

    2011-12-01

    Past research has shown that drastically disturbed and degraded soils can offer a high potential for soil organic carbon and aboveground carbon sequestration. Little work has been done on both the functioning of soil carbon accumulation and turnover in reclaimed surface mining soils. Reclamation practices of surface coal mine soils in the Southern Appalachian forest region of the United States emphasizes heavy compaction of surface material to provide slope stability and reduce surface erosion, and topsoil is not typically added. An analysis of the previously collected data has provided a 14 year chronosequence of SOC uptake and development in the soil column and revealed that these soils are sequestering carbon at a rate of 1.3 MgC ha-1 yr-1, which is 1.6 to 3 times less than mining soils reported for other regions. Results of bulk density analysis indicate a contrast between 0 - 10 cm (1.51 g cm-3) and 10 - 50 cm (2.04 g cm-3) depth intervals. Aggregate stability was also quantified as well as dynamic soil texture measurements. With this analysis, it has been established that these soils are well below their potential in terms of the ability to store and cycle carbon and other nutrients as well their ability to sustain a fully-functioning forested ecosystem typical for the region. We are taking an integrated approach that relies on ecological observations for present conditions combined with computational modeling to understand long-term soil organic carbon (SOC) accumulation and turnover in regards to SOC sequestration potential and quantification of specific processes by which these soils develop. A dual-isotope end-member model, utilizing the carbon 13 and nitrogen 15 stable isotopes, is being developed to provide greater input into the mathematical separation of organic carbon derived from new soil inputs and existing coal carbon. Soils from the study sites have been isolated into three distinct size pools, and elemental and isotopic analysis of these samples

  1. [Latitudinal Changes in Plant Stoichiometric and Soil C, N, P Stoichiometry in Loess Plateau].

    PubMed

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

    2015-08-01

    Field investigations and sampling were conducted in Loess Plateau, including Fu County, Ganquan County, Ansai County, Jingbian County and Hengshan County and Yuyang District. Our objective was to examine changes of leaf and soil stoichiometry characteristics along latitudinal gradient in Loess Plateau, and to provide references for the prediction of soil nutrient status of the ecosystem and constraints of plant nutrition elements in Loess Plateau. The results showed that (1) Across the 35.95 degrees-38.36 degrees N latitude gradient, leaf C, N and P stoichiometry were ranging from 336.95 to 477.38 mg x g(-1) for C, from 18.09 to 33.173 mg x g(-1) for N and from 1.07 to 1.73 mg x g(-1) for P, the arithmetic means were 442.9 mg x g(-1), 25.79 mg x g(-1) and 1.37 mg x g(-1), separately, the variation coefficients were 11.9%, 17.4% and 13.3%. There were obvious correlation between leaf C, N, P and latitude, leaf C, C : N ratio and C: P ratio significantly decreased with the increasing latitude, while leaf N and P significantly increased with the increasing latitude. The relationship between N: P ratio and latitude was not significant. (2) The content of soil organic C and soil total N decreased with increasing latitude and soil layer. In contrast, with the increase of latitude, soil P increased and then decreased. In the 0-10 cm, 10-20 cm soil layers, soil C: N ratio did not change significantly with latitude, while in the 20-40 cm layer, C: N ratio decreased obviously, but soil C: P and N: P ratios decreased with the increasing latitude in all soil layers. (3) Leaf C, C: N and C: P ratios were correlated to soil organic C, soil total N and soil total P in all soil layers, leaf N and P were correlated to soil organic C and soil total N, while leaf N: P ratio was not correlated to soil organic C, soil total N and soil total P. There was a certain correlation between the leaf C, N, P and latitude, however, the correlations between leaf and soil C, N, P were inconsistent

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

    PubMed

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

    2015-08-01

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

  3. [Effects of litter and mineral nitrogen input on soil organic carbon decomposition in subtropical mixed forest in Dinghu Mountain, South China].

    PubMed

    Sun, Li-Juan; Zeng, Hui; Guo, Da-Li

    2011-12-01

    In July-December 2010, a complete factor-controlled experiment was conducted to study the effects of litter and mineral nitrogen addition on soil organic matter decomposition (soil respiration) at the depths of 0-10 cm and 20-30 cm in Dinghu Mountain National Reserve. Coniferous needle litter and broadleaved litter were added, respectively, and 70 g N x m(-2) x yr(-1) of NH4 NO3 was applied to simulate soil nitrogen saturation whereas soil mineral nitrogen was removed by ion-exchange membrane to simulate the decreased nitrogen absorption by root. The addition of both needle litter and broadleaved litter increased the respiration rate of soil-litter system significantly from July to November, but this effect disappeared in December. Both mineral nitrogen application and soil mineral nitrogen removal increased the soil-litter respiration significantly. These results suggest that litter decomposed completely in a short period therefor had limited effects on soil organic matter decomposition and accumulation, and thus, foliar litters could be not the major source of soil organic matter, whereas soil mineral nitrogen removal could obviously promote the soil organic matter decomposition in the system.

  4. Impact of different tillage treatments on soil respiration and microbial activity for different agricultural used soils in Austria

    NASA Astrophysics Data System (ADS)

    Klik, Andreas; Scholl, Gerlinde; Baatar, Undrakh-Od

    2015-04-01

    Soils can act as a net sink for sequestering carbon and thus attenuating the increase in atmospheric carbon dioxide if appropriate soil and crop management is applied. Adapted soil management strategies like less intensive or even no tillage treatments may result in slower mineralization of soil organic carbon and enhanced carbon sequestration. In order to assess the impact of different soil tillage systems on carbon dioxide emissions due to soil respiration and on soil biological activity parameters, a field study of three years duration (2007-2010)has been performed at different sites in Austria. Following tillage treatments were compared: 1) conventional tillage (CT) with plough with and without cover crop during winter period, 2) reduced tillage (RT) with cultivator with cover crop, and 3) no-till (NT) with cover crop. Each treatment was replicated three times. At two sites with similar climatic conditions but different soil textures soil CO2 efflux was measured during the growing seasons in intervals of one to two weeks using a portable soil respiration system consisting of a soil respiration chamber attached to an infrared gas analyzer. Additionally, concurrent soil temperature and soil water contents of the top layer (0-5 cm)were measured. For these and additional three other sites with different soil and climatic conditions soil samples were taken to assess the impact of tillage treatment on soil biological activity parameters. In spring, summer and autumn samples were taken from each plot at the soil depth of 0-10, 10-20, and 20-30 cm to analyze soil microbial respiration (MR), substrate induced respiration (SIR), beta-glucasidase activity (GLU) and dehydrogenase (BHY). Samples were sieved (2 mm) and stored at 4 °C in a refrigerator. Analyses of were performed within one month after sampling. The measurements show a high spatial variability of soil respiration data even within one plot. Nevertheless, the level of soil carbon dioxide efflux was similar for

  5. [Soil salinity in greenland irrigated with reclaimed water and risk assessment].

    PubMed

    Pan, Neng; Chen, Wei-Ping; Jiao, Wen-Tao; Zhao, Zhong-Ming; Hou, Zhen-An

    2012-12-01

    Compared to drinking water or groundwater, reclaimed water contains more salts. Therefore, the effects of application of reclaimed water on the soil salinity have received great attentions. To evaluate the potential risks posed by long-term reclaimed water irrigation, we collected surface soil samples from urban green lands and suburban farmlands of Beijing represented different irrigation durations. The electrical conductivity (EC) and sodium adsorption ratio (SAR) in soils were measured subsequently. Both EC1:5 and SAR1.5 from the green land and farmland soils irrigated with reclaimed water were significantly higher than those of control treatments (drinking water or groundwater irrigation). The EC1:5 values increased by 12.4% and 84.2% than control treatments in the greenland and farmland, respectively. The SAR1:5 values increased by 64.5% and 145.8% than control treatments, respectively. No significant differences of both EC1:5 and SAR1:5 were found between of 0-10 cm and 10-20 cm soil layer. A slight decrease of soil porosity was observed. The field investigation suggested there was a high potential of soil salinization under long-term reclaimed water irrigation. Proper management practices should be implemented to minimize the soil salinity accumulation risk when using reclaimed water for irrigation in Beijing.

  6. [Soil microbial community structure of two types of forests in the mid-subtropics of China].

    PubMed

    Han, Shi-zhong; Gao, Ren; Li, Ai-ping; Ma, Hong-liang; Yin, Yun-feng; Si, You-tao; Chen, Shi-dong; Zheng, Qun-rui

    2015-07-01

    Soil microbial community structures were analyzed by biomarker method of phospholipid fatty acid (PLFA) for a natural forest dominated by Castanopsis fabri (CF) and an adjacent plantation of Cunninghamia lanceolata (CL) in the mid-subtropics of China. The results showed that the amounts of total PLFAs, bacterial PLFAs, fungal PLFAs, gram-positive bacterial PLFAs and gramnegative bacterial PLFAs in the 0-10 cm soil layer were higher than in the 10-20 cm soil layer, and each type of PLFAs in CF were higher than in CL. In either soil layer of the two forest types, the contents of bacterial PLFAs were significantly higher than those of fungal PLFAs. In the two forests, the contents of bacterial PLFAs accounted for 44%-52% of total PLFAs, while the contents of fungal PLFAs just accounted for 6%-8%, indicating the bacteria were dominant in the soils of the two vegetation types. Principal component analysis showed that the influence of vegetation types was greater than soil depth on the microbial community structures. Correlation analysis showed that gram-negative bacterial PLFAs, gram-positive bacterial PLFAs and bacterial PLFAs were significantly negatively correlated with pH, positively with water content, and the PLFAs of main soil microorganism groups were significantly positively correlated with soil total nitrogen, organic carbon, C/N and ammonium.

  7. Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

    PubMed

    Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

    2011-09-01

    Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

  8. [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.

  9. 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.

  10. Cost of owning and operating a 9-32-0/10-34-0 facility. [Ammonium polyphosphate base suspension

    SciTech Connect

    Williams, R.J.

    1984-04-01

    This analysis specifies the relative economics of a 20-ton per hour combination 9-32-0/10-34-0 plant for a midwest location. The major points are: (A) Initial investment in on-site plant and equipment ranges from $192,000 to $242,000 (excluding storage costs) depending on use of fluid clay or dry clay respectively. Storage costs are a major cost outlay depending on scheduling of raw materials and final products. When storage and off-site costs such as truck scales, office building, and spare parts inventory were added, initial investment was from $356,000 (using fluid clay) to $406,000 (using dry clay). Since storage costs may be conservative, a total investment of $450,000 to $500,000 appears reasonable for planning purposes. (B) Annualized costs show raw materials as the predominant cost factor. For a 20-ton per hour plant, operated between 5000 tpy and 11,000 tpy, raw materials cost account for 81 to 89 percent of total annual costs. (C) Expected delivered phosphoric acid prices (1984) used in the analysis were $3.65 per unit (Ortho) and $4.56 per unit (Super). With a 60/40 annual production ratio in producing 10-34-0/9-32-0, the weighted break-even price ranged from $202 per ton for a 5000 tpy volume to $184 per ton for an 11,000 tpy volume. When revenues for the final product were set at $210 per ton for 10-34-0 and $183 per ton for 9-32-0, the breakeven volume was between 5000 and 6000 tons per year. As price estimates for the final products go down, this break-even volume will increase if everything else remains the same. (D) Although these estimates suggest economic feasibility for volumes above the breakeven point, this feasibility is highly sensitive to raw material cost and final product prices. Thus, quotes on prices and tonnages should not be divorced from assumptions on raw materials and revenues. 1 reference, 2 figures, 6 tables.

  11. Conducting Retrospective Ontological Clinical Trials in ICD-9-CM in the Age of ICD-10-CM

    PubMed Central

    Venepalli, Neeta K; Shergill, Ardaman; Dorestani, Parvaneh; Boyd, Andrew D

    2014-01-01

    OBJECTIVE To quantify the impact of International Classification of Disease 10th Revision Clinical Modification (ICD-10-CM) transition in cancer clinical trials by comparing coding accuracy and data discontinuity in backward ICD-10-CM to ICD-9-CM mapping via two tools, and to develop a standard ICD-9-CM and ICD-10-CM bridging methodology for retrospective analyses. BACKGROUND While the transition to ICD-10-CM has been delayed until October 2015, its impact on cancer-related studies utilizing ICD-9-CM diagnoses has been inadequately explored. MATERIALS AND METHODS Three high impact journals with broad national and international readerships were reviewed for cancer-related studies utilizing ICD-9-CM diagnoses codes in study design, methods, or results. Forward ICD-9-CM to ICD-10-CM mapping was performing using a translational methodology with the Motif web portal ICD-9-CM conversion tool. Backward mapping from ICD-10-CM to ICD-9-CM was performed using both Centers for Medicare and Medicaid Services (CMS) general equivalence mappings (GEMs) files and the Motif web portal tool. Generated ICD-9-CM codes were compared with the original ICD-9-CM codes to assess data accuracy and discontinuity. RESULTS While both methods yielded additional ICD-9-CM codes, the CMS GEMs method provided incomplete coverage with 16 of the original ICD-9-CM codes missing, whereas the Motif web portal method provided complete coverage. Of these 16 codes, 12 ICD-9-CM codes were present in 2010 Illinois Medicaid data, and accounted for 0.52% of patient encounters and 0.35% of total Medicaid reimbursements. Extraneous ICD-9-CM codes from both methods (Centers for Medicare and Medicaid Services general equivalent mapping [CMS GEMs, n = 161; Motif web portal, n = 246]) in excess of original ICD-9-CM codes accounted for 2.1% and 2.3% of total patient encounters and 3.4% and 4.1% of total Medicaid reimbursements from the 2010 Illinois Medicare database. DISCUSSION Longitudinal data analyses post-ICD-10

  12. Small-scale variability in solute transport processes in a homogeneous clay loam soil

    SciTech Connect

    Garrido, F.; Ghodrati, M.; Chendorain, M.; Campbell, C.G.

    1999-12-01

    Small-scale variations in transport parameters may have a profound influence on larger scale flow processes. Fiber-optic miniprobes (FOMPs) provide the opportunity to continuously measure solute resident concentration in small soil volumes. A 20-channel multi-plexed-FOMP system was used in repeated miscible displacements in a repacked clay loam soil column to examine small-scale, point-to-point variability in convective-dispersive transport processes. Transport parameters, measured 10 cm below the surface, were compared at two drip irrigation point densities and two fluxes. Irrigation densities of one irrigation drip point per 4 cm{sup 2} and 11 cm{sup 2} of column surface area produced similar results. The breakthrough curves measured at 0.10 cm h{sup {minus}1} had a larger immobile phase than at a flux of 1.07 cm h{sup {minus}1}. In the clay loam soil the mobile-immobile model fit the breakthrough curves better than the convective-dispersive equation (CDE), with r{sup 2} values of 99.6 and 97.1, respectively. This analysis demonstrated that dispersion and mass recovery were much more variable than pore water velocity in this repacked clay loam soil. However, even in the most variable transport conditions encountered, only 17 sampling points were necessary to describe the column average transport parameters within 20% of the mean.

  13. Carbon mineralization in surface and subsurface soils in a subtropical mixed forest in central China

    NASA Astrophysics Data System (ADS)

    Liu, F.; Tian, Q.

    2014-12-01

    About a half of soil carbon is stored in subsurface soil horizons, their dynamics have the potential to significantly affect carbon balancing in terrestrial ecosystems. However, the main factors regulating subsurface soil carbon mineralization are poorly understood. As affected by mountain humid monsoon, the subtropical mountains in central China has an annual precipitation of about 2000 mm, which causes strong leaching of ions and nutrition. The objectives of this study were to monitor subsurface soil carbon mineralization and to determine if it is affected by nutrient limitation. We collected soil samples (up to 1 m deep) at three locations in a small watershed with three soil layers (0-10 cm, 10-30 cm, below 30 cm). For the three layers, soil organic carbon (SOC) ranged from 35.8 to 94.4 mg g-1, total nitrogen ranged from 3.51 to 8.03 mg g-1, microbial biomass carbon (MBC) ranged from 170.6 to 718.4 μg g-1 soil. We measured carbon mineralization with the addition of N (100 μg N/g soil), P (50 μg P/g soil), and liable carbon (glucose labeled by 5 atom% 13C, at five levels: control, 10% MBC, 50% MBC, 100% MBC, 200% MBC). The addition of N and P had negligible effects on CO2 production in surface soil layers; in the deepest soil layer, the addition of N and P decreased CO2 production from 4.32 to 3.20 μg C g-1 soil carbon h-1. Glucose addition stimulated both surface and subsurface microbial mineralization of SOC, causing priming effects. With the increase of glucose addition rate from 10% to 200% MBC, the primed mineralization rate increased from 0.19 to 3.20 μg C g-1 soil carbon h-1 (fifth day of glucose addition). The magnitude of priming effect increased from 28% to 120% as soil layers go deep compare to the basal CO2 production (fifth day of 200% MBC glucose addition, basal CO2 production rate for the surface and the deepest soil was 11.17 and 2.88 μg C g-1 soil carbon h-1). These results suggested that the mineralization of subsurface carbon is more

  14. Long term impact of different tillage practices on soil C sequestration potential

    NASA Astrophysics Data System (ADS)

    Valboa, Giuseppe; Lagomarsino, Alessandra; Papini, Rossella; Brandi, Giorgio; Elio Agnelli, Alessandro; Simoncini, Stefania; Vignozzi, Nadia; Pellegrini, Sergio

    2013-04-01

    Long-term experiments provide important information on the impact of agricultural management practices on soil quality. In 1994, a trial was started to investigate the effects of four different tillage systems on organic carbon and physical properties of a Calcari Fluvic Cambisol loam soil under continuous maize. The tillage practices compared were: conventional tillage by mould-board ploughing to 40 cm depth (DP); ripper sub-soiling to 40-45 cm (RS); shallow tillage by mould-board ploughing to 20 cm depth (SP); minimum tillage by disk harrowing to 10-15 cm (DH). Soil carbon pool, bulk density, macroporosity and aggregate stability were studied at different depth increments (0-10, 10-20, 20-30 and 30-40 cm) and by two repeated samplings (in 1999 and 2011), in order to evaluate their temporal evolution under the different tillage systems. For a better understanding of mechanisms leading to C sequestration, a qualitative characterization of soil organic matter (OM) was performed by acid hydrolysis (HCl 6N), in order to separate the labile and the recalcitrant fractions. After 18 years of treatments we hypothesized changes in OM content and quality, as well as in its vertical distribution, due to tillage practices. At the end of the trial, soil total organic carbon (TOC) stock increased in the surface layers under DH (to 10 cm depth), RS (to 20 cm depth) and SP (to 10 cm depth), while it was unchanged under DP. When considering the whole 0-40 cm layer, all tillage treatments resulted in no significant variation in TOC stock. OM quality and its evolution over time showed well defined differences among treatments: the OM recalcitrant fraction increased under RS (up to 30 cm depth), decreased under DP (up to 40 cm depth) and showed no significant changes under DH and SP. The negative impact of DP on C stabilization was confirmed by a significant decrease of the recalcitrant to TOC ratio in the whole sampled layer. In conclusion, DP showed the worst impact on C storage

  15. [Effects of long-term tillage and rice straw returning on soil nutrient pools and Cd concentration].

    PubMed

    Tang, Wen-guang; Xiao, Xiao-ping; Tang, Hai-ming; Zhang, Hai-lin; Chen, Fu; Chen, Zhong-du; Xue, Jian-fu; Yang, Guang-li

    2015-01-01

    The objective of this study was to assess the effects of tillage and straw returning on soil nutrient and its pools, and soil Cd concentration, and to identify the strategies for rational tillage and remediation of Cd contaminated paddy fields. The experiment was established with no-tillage with straw retention (NTS) , rotary tillage with straw incorporation (RTS) , conventional plow tillage with straw incorporation (CTS), conventional plow tillage with straw removed ( CT) from 2005 to 2013. The results indicated that tillage and rice straw retention had a great impact on soil properties at 0-10 cm soil depth. The soil aeration, and concentrations of soil nutrient and soil Cd increased under CTS, CT, and RTS. Due to the shallow plow layers, soil nutrient pools and the Cd concentration in rice shoot decreased in long-term tilled soil. Under long-term no-tillage, the soil bulk, soil nutrient pools and Cd concentration in rice shoot increased, but concentrations of soil nutrients decreased. In addition, rice straw returning significantly increased the soil nutrient concentrations, cation exchange capacity, depth of plow layer, and soil nutrient pools. However, the Cd in the rice straw was also returned to the soil by rice straw returning, which would not benefit the remediation of soil Cd. Therefore, it is necessary to improve tillage and straw retention practices due to the disadvantages of long-term continuous single tillage method and rice straw returning practices. Some recommended managements (e.g., rotational tillage or subsoiling, reducing straw returning amount, and rotational straw returning) could be good options in enhancing soil fertility and remedying soil pollution.

  16. [Effects of nitrogen addition on available nitrogen content and acidification in cold-temperate coniferous forest soil in the growing season].

    PubMed

    Chen, Gao-Qi; Fu, Wa-Li; Luo, Ya-Chen; Gao, Wen-Long; Li, Sheng-Gong; Yang, Hao

    2014-12-01

    Based on a low-level and multi-form N addition control experiment, this study took cold-temperate coniferous forest in Daxing'an Ling as the research object. After long-term and continuous nitrogen addition in situ, the available nitrogen (NH4(+) -N & NO3(-) -N) contents and pH values of the soil (0-10 cm) were measured in the early growing season (May) and the peak growing season (August) in 2010, 2012 and 2013. The results showed that, the available nitrogen in the early and peak growing seasons was mainly NH4(+) -N which accounted for over 96% of the inorganic nitrogen content, while the content of NO3(-) -N was very low. With the time extension of nitrogen addition, the effects of nitrogen addition on the NH4(+) -N content in 0-10 cm soil were more obvious in the early growing season than that in the peak growing season, and the NH4(+) -N content was mainly affected by the type of nitrogen addition. On the contrary, the NO3(-) -N content in 0-10 cm soil was higher in the peak growing season than that in the early growing season. The effect of N input was obvious on NO3(-) -N content in both early and peak growing seasons, and low nitrogen treatment tended to promote the enrichment of NO3(-) -N. As time went on, the response of NH4(+) -N and NO3(-) -N content to N addition was changed from insignificant in the early stage to significant in the late stage. N addition had a significant impact on the pH value of the 0-10 cm soil in the early and peak growing seasons. The pH values of the soil with low nitrogen treatment and the soil in the peak growing season were relatively lower. With the extension of the nitrogen addition time, the response of pH value also turned from insignificant in the early stage to significant in the late stage. Because of the long-term and continuous nitrogen addition, the 0 - 10 cm soil in this cold-temperate coniferous forest was obviously acidified.

  17. Spatio-temporal dynamics of arbuscular mycorrhizal fungi associated with glomalin-related soil protein and soil enzymes in different managed semiarid steppes.

    PubMed

    Wang, Qi; Bao, Yuying; Liu, Xiaowei; Du, Guoxin

    2014-10-01

    Temporal and spatial patterns of arbuscular mycorrhizal fungi (AMF) and glomalin and soil enzyme activities were investigated in different managed semiarid steppes located in Inner Mongolia, North China. Soils were sampled in a depth up to 30 cm from non-grazed, overgrazed, and naturally restored steppes from June to September. Roots of Leymus chinense (Trin.) Tzvel. and Stipagrandis P. Smirn. were also collected over the same period. Results showed that overgrazing significantly decreased the total mycorrhizal colonization of S. grandis; total colonization of L. chinensis roots was not significantly different in the three managed steppes. Nineteen AMF species belonging to six genera were isolated. Funneliformis and Glomus were dominant genera in all three steppes. Spore density and species richness were mainly influenced by an interaction between plant growth stage and management system (P < 0.001). Spore densities were higher in 0-10-cm soil depth. AMF species richness was significantly positively correlated with soil acid phosphatase activity, alkaline phosphatase activity, and two Bradford-reactive soil protein (BRSP) fractions (P < 0.01). It is concluded that the dynamics of AMF have highly temporal and spatial patterns that are related to soil glomalin and phosphatase activity in different managed semiarid steppes. Based on these observations, AMF communities could be useful indicators for evaluating soil quality and function of semiarid grassland ecosystems.

  18. Detections of 2 cm formaldehyde emissions towards Galactic star-forming regions with 6 cm counterpart

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Shen, Zhi-Qiang; Li, Xiao-Qiong; Yang, Kai; Li, Juan; Wang, Jun-Zhi; Wu, Ya-Jun; Zhao, Rong-Bin; Wang, Jin-Qing; Dong, Jian; Jiang, Dong-Rong; Li, Bin

    2017-01-01

    We report the detections of H2CO emission at the 2 cm transition towards Galactic star-forming regions with known 6 cm counterpart using the Shanghai Tianma Radio Telescope (TMRT). One significant detection (in NGC7538) and two possible detections (in G23.01-0.41 and G29.96-0.02) were made. Comparing with previous observations, we found that there is a time lag of appearance of 2 cm and 6 cm emissions detected in NGC7538, contradicting with the prediction of radiative pumping via radio continuum radiation. Combinations of the variability of 6 cm masers in NGC7538 suggest that collisional pumping via high-velocity shocks could better explain the 6 cm H2CO maser emission. Under this scheme, excitation of the 2 cm maser may require a higher collision energy compared to the 6 cm transition.

  19. Vertical distribution and migration of global fallout Pu in forest soils in southwestern China.

    PubMed

    Bu, Wenting; Zheng, Jian; Guo, Qiuju; Uchida, Shigeo

    2014-10-01

    Soil samples collected in southwestern China were analyzed for Pu isotopes. The (240)Pu/(239)Pu atom ratios were around 0.18, which indicated the dominant source of global fallout. Consistent sub-surface maximums followed by exponential decline of (239+240)Pu activities in the soil cores were observed. Most of the Pu has still remained in the 0-10 cm layers since its deposition. Convection velocities and dispersion coefficients for Pu migration in the soils were estimated by the convection-dispersion equation (CDE) model. The effective convection velocities and effective dispersion coefficients ranged from 0.05 to 0.11 cm/y and from 0.06 to 0.29 cm(2)/y, respectively. Other factors that control the vertical migration of Pu in soil besides precipitation, soil particle size distribution and organic matter were suggested. Long-term migration behaviors of Pu in the soils were simulated. The results provide the Pu background baseline for further environmental monitoring and source identification of non-global fallout Pu inputs in the future.

  20. [Microbial community abundance and diversity in typical karst ecosystem to indicate soil carbon cycle].

    PubMed

    Jin, Zhen-Jiang; Tang, Hua-Feng; Li, Min; Huang, Bing-Fu; Li, Qiang; Zhang, Jia-Yu; Li, Gui-Wen

    2014-11-01

    The soil microbial characteristics were detected to clarify their indications in organic carbon cycle in karst system. Soil samples from three karst types (saddle, depression and slop) at 0-10 cm, 10-20 cm and 20-30 cm layers were collected in the Yaji Karst Experimental Site, a typical karst ecosystem. The microbial diversity and abundance were assayed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and fluorescence quantitative PCR. The data showed that the highest abundance of 16S rRNA and 18S rRNA were in depression with 1.32 x 10(11) copies x g(-1) and in saddle with 1.12 x 10(10) copies x g(-1), respectively. The abundance of 16S rRNA in saddle and depression decreased from top to bottom, while that of 18S rRNA in three karst forms decreased, which showed that the abundance changed consistently with soil organic carbon (SOC). The 3 diversity indices of 16S rRNA and 6 diversity indices of 18S rRNA increased from top to bottom in soil profiles of three karst forms. These results showed that microbial diversity changed conversely with the abundance and SOC in soil profile. It can be concluded that the abundance was more important than the diversity index for soil carbon cycle in karst system.

  1. 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.

  2. Soil Fertility Gradient in the Restinga Ecosystem

    NASA Astrophysics Data System (ADS)

    América Castelar da Cunha, Joana; Casagrande, José Carlos; Soares, Marcio Roberto; Martins Bonilha, Rodolfo

    2013-04-01

    The restinga ecosystem (coastal plain vegetation) can be termed as a set of plant communities that suffer strong influenced by fluvial and marine factors and is characterized as an ecosystem of great biological diversity, therefore, represents areas of great importance in the context of ecological preservation. The degradation processes from many forms of anthropogenic disturbances that has taken place since the colonization of the country, made studies on the characterization and dynamics of soil fertility of these areas even more important in relation to the maintenance of its biodiversity and conservation. The sites studied were the Cardoso Island and Comprida Island, and in these, we analyzed four physiognomies, restinga, low restinga, dune and antedune (from continent to ocean). Chemical analyses were performed and soil salinity in these areas in depths 0-5; 0-10; 0-20; 20-40; 40-60 cm. In all soils the cationic exchange capacity was intimately associated with the concentration of soil organic matter, which makes this parameter essential to the maintenance of soil fertility of these areas; in more superficial layers (0-20 cm) there was an increase of pH and base saturation and decline of organic matter, aluminum saturation and cationic exchange capacity in the nearby sea, physiognomies what determines the existence of fertility gradient towards the continent-coast; restinga forests showed a chemical standard that is heavily marked by sandy texture, high degree of leaching, nutrient poverty, low base saturation, high saturation by aluminum and acidity, opposite conditions to soils of the dunes and antedunes, with the exception of sandy texture; despite the existence of a chemical gradient of fertility among the physiognomies studied it is possible to determine the soil acts more strongly as a physical support than as provider of fertility; as for salinity, soil collected in Cardoso Island did not present salinity in any depth, a fact which can be explained due

  3. Soil microbial diversity in the vicinity of desert shrubs.

    PubMed

    Saul-Tcherkas, Vered; Unc, Adrian; Steinberger, Yosef

    2013-04-01

    Water and nutrient availability are the major limiting factors of biological activity in arid and semiarid ecosystems. Therefore, perennial plants have developed different ecophysiological adaptations to cope with harsh conditions. The chemical profile of the root exudates varies among plant species and this can induce variability in associated microbial populations. We examined the influence of two shrubs species, Artemisia sieberi and Noaea mucronata, on soil microbial diversity. Soil samples were collected monthly, from December 2006 to November 2007, near canopies of both shrubs (0-10-cm depth). Samples were used for abiotic tests and determination of soil bacterial diversity. No significant differences were found in the abiotic variables (soil moisture, total organic matter, and total soluble nitrogen (TSN)) between soil samples collected from under the two shrubs during the study period. No obvious differences in the Shannon-Weaver index, evenness values, or total phylogenetic distances were found for the soil microbial communities. However, detailed denaturing gradient gel electrophoresis (DGGE) clustering as well as taxonomic diversity analyses indicated clear shifts in the soil microbial community composition. These shifts were governed by seasonal variability in water availability and, significantly, by plant species type.

  4. 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.

  5. Impact of orchard and tillage management practices on soil leaching of atrazine, potassium, magnesium, manganese, iron, ammonium, nitrates and phosphates

    NASA Astrophysics Data System (ADS)

    Szajdak, L.; Lipiec, J.; Siczek, A.; Kotowska, U.; Nosalewicz, A.

    2009-04-01

    The experiments were carried out on an Orthic Luvisol developed from loess, over limestone, at the experimental field of Lublin Agricultural University in Felin (51o15'N, 22o35'E), Poland. The investigation deals with the problems of leaching's rate of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,2,3-triazine), potassium, magnesium, manganese, iron, ammonium, nitrates and phosphates from two management systems of soil: (i) conventionally tilled field with main tillage operations including stubble cultivator (10 cm) + harrowing followed by mouldboard ploughing to 20 cm depth, and crop rotation including selected cereals, root crops and papillionaceous crops, (ii) 35-year-old apple orchard field (100x200m) with a permanent sward that was mown in the inter-rows during the growing season. The conventionally tilled plot was under the current management practice for approximately 30 years. Field sites were close to each other (about 150 m). Core samples of 100 cm3 volume and 5 cm diameter were taken from two depths 0-10 cm and 10-20 cm, and were used to determine the soil water characteristic curve. It was observed that management practices impacted on the physic-chemical properties of soils. pH (in H2O) in tilled soil ranged from 5.80 to 5.91. However soil of orchard soil revealed higher values of pH than tilled soil and ranged from 6.36 to 6.40. The content of organic carbon for tilled soil ranged from 1.13 to 1.17%, but in orchard soil from 1.59 to 1.77%. Tillled soil showed broader range of bulk density 1.38-1.62 mg m-3, than orchard soil 1.33-134 mg m-3. The first-order kinetic reaction model was fitted to the experimental atrazine, potassium, magnesium, manganese, iron, nitrates, ammonium and phosphates leaching vs. time data. The concentrations of leached chemical compounds revealed linear curves. The correlation coefficients ranged from -0.873 to -0.993. The first-order reaction constants measured for the orchard soils were from 3.8 to 19 times higher than

  6. 21 CM searches for DIM galaxies

    NASA Astrophysics Data System (ADS)

    Disney, Mike; Banks, Gareth

    1997-04-01

    We review very strong selection effects which operate against the detection of dim (i.e. low surface brightness) galaxies. The Parkes multibeam instrument offers a wonderful opportunity to turn up new populations of such galaxies. However, to explore the newly accessible parameter space, it will be necessary to survey both a very deep patch (105 s/pointing, limiting N hi ˜ 1018 cm-2) and a deep patch (104 s/pointing, limiting N hi ˜ 3 × 1018 cm-2) in carefully selected areas, and we outline the case to do this.

  7. A novel lead compound CM-118

    PubMed Central

    Meng, Lanfang; Shu, Mengjun; Chen, Yaqing; Yang, Dexiao; He, Qun; Zhao, Hui; Feng, Zhiyong; Liang, Chris; Yu, Ker

    2014-01-01

    The anaplastic lymphoma kinase (ALK) and the c-Met receptor tyrosine kinase play essential roles in the pathogenesis in multiple human cancers and present emerging targets for cancer treatment. Here, we describe CM-118, a novel lead compound displaying low nanomolar biochemical potency against both ALK and c-Met with selectivity over >90 human kinases. CM-118 potently abrogated hepatocyte growth factor (HGF)-induced c-Met phosphorylation and cell migration, phosphorylation of ALK, EML4-ALK, and ALK resistance mutants in transfected cells. CM-118 inhibited proliferation and/or induced apoptosis in multiple c-Met- and ALK-addicted cancer lines with dose response profile correlating target blockade. We show that the CM-118-induced apoptosis in c-Met-amplified H1993 NSCLC cells involved a rapid suppression of c-Met activity and c-Met-to-EGFR cross-talk, and was profoundly potentiated by EGFR inhibitors as shown by the increased levels of apoptotic proteins cleaved-PARP and Bim as well as reduction of the survival protein Mcl-1. Bim-knockdown or Mcl-1 overexpression each significantly attenuated apoptosis. We also revealed a key role by mTOR in mediating CM-118 action against the EML4-ALK-dependent NSCLC cells. Abrogation of EML4-ALK in H2228 cells profoundly reduced signaling capacity of the rapamycin-sensitive mTOR pathway leading to G1 cell cycle arrest and mitochondrial hyperpolarization, a metabolic perturbation linked to mTOR inhibition. Depletion of mTOR or mTORC1 inhibited H2228 cell growth, and mTOR inhibitors potentiated CM-118’s antitumor activity in vitro and in vivo. Oral administration of CM-118 at a wide range of well tolerated dosages diminished c-Met- and ALK phosphorylation in vivo, and caused tumor regression or growth inhibition in multiple c-Met- and ALK-dependent tumor xenografts in mice. CM-118 exhibits favorable pharmacokinetic and drug metabolism properties hence presents a candidate for clinical evaluation. PMID:24618813

  8. Stratification of carbon fractions and carbon management index in deep soil affected by the Grain-to-Green Program in China.

    PubMed

    Zhao, Fazhu; Yang, Gaihe; Han, Xinhui; Feng, Yongzhong; Ren, Guangxin

    2014-01-01

    Conversion of slope cropland to perennial vegetation has a significant impact on soil organic carbon (SOC) stock in A horizon. However, the impact on SOC and its fraction stratification is still poorly understood in deep soil in Loess Hilly Region (LHR) of China. Samples were collected from three typical conversion lands, Robinia psendoacacia (RP), Caragana Korshinskii Kom (CK), and abandoned land (AB), which have been converted from slope croplands (SC) for 30 years in LHR. Contents of SOC, total nitrogen (TN), particulate organic carbon (POC), and labile organic carbon (LOC), and their stratification ratios (SR) and carbon management indexes (CMI) were determined on soil profiles from 0 to 200 cm. Results showed that the SOC, TN, POC and LOC stocks of RP were significantly higher than that of SC in soil layers of 0-10, 10-40, 40-100 and 100-200 cm (P<0.05). Soil layer of 100-200 cm accounted for 27.38-36.62%, 25.10-32.91%, 21.59-31.69% and 21.08-26.83% to SOC, TN, POC and LOC stocks in lands of RP, CK and AB. SR values were >2.0 in most cases of RP, CK and AB. Moreover, CMI values of RP, CK, and AB increased by 11.61-61.53% in soil layer of 100-200 cm compared with SC. Significant positive correlations between SOC stocks and CMI or SR values of both surface soil and deep soil layers indicated that they were suitable indicators for soil quality and carbon changes evaluation. The Grain-to-Green Program (GTGP) had strong influence on improving quantity and activity of SOC pool through all soil layers of converted lands, and deep soil organic carbon should be considered in C cycle induced by GTGP. It was concluded that converting slope croplands to RP forestlands was the most efficient way for sequestering C in LHR soils.

  9. Rapid response of soil fungal communities to low and high intensity fire

    NASA Astrophysics Data System (ADS)

    Smith, Jane E.; Cowan, Ariel D.; Reazin, Chris; Jumpponen, Ari

    2016-04-01

    Contemporary fires have created high-severity burn areas exceeding historical distributions in forests in the western United States. Until recently, the response of soil ecosystems to high intensity burns has been largely unknown. In complementary studies, we investigated the environmental effect of extreme soil heating, such that occurs with the complete combustion of large down wood during wildfires, on soil fungi and nutrients. We used TRFLP and next generation sequencing (Illumina MiSeq) to investigate the fungal communities. During the burning of large down wood, temperatures lethal to fungi were detected at 0-cm, 5-cm, and 10-cm depths in soils compared to 0-cm depth in soils receiving low intensity broadcast burns. We compared the soil fungal diversity in ten high intensity burned plots paired with adjacent low intensity burned plots before and one week after at 0-10 cm soil depth. Nonmetric Multidimensional Scaling (NMS) ordinations and analyses of taxon frequencies reveal a substantial community turnover and corresponding near complete replacement of the dominant basidiomycetes by ascomycetes in high intensity burns. These coarse-level taxonomic responses were primarily attributable to a few fire-responsive (phoenicoid) fungi, particularly Pyronema sp. and Morchella sp., whose frequencies increased more than 100-fold following high intensity burns. Pinus ponderosa seedlings planted one week post-burn were harvested after four months for EMF root tip analysis. We found: a) greater differences in soil properties and nutrients in high intensity burned soils compared to low intensity burned and unburned soils; b) no differences in EMF richness and diversity; and c) weak differences in community composition based on relative abundance between unburned and either burn treatments. These results confirm the combustion of large downed wood can alter the soil environment directly beneath it. However, an EMF community similar to low burned soils recolonized high

  10. Heavy metal pattern and solute concentration in soils along the oldest highway of the world--the AVUS Autobahn.

    PubMed

    Kluge, Björn; Wessolek, Gerd

    2012-11-01

    Highways and main roads are a potential source of contamination for the surrounding environment. High traffic rates result in elevated heavy metal concentrations in road runoff, soil and water seepage, which has attracted much attention in the recent past. Nonetheless, investigations of pollutants in roadside soils are still a subject of major interest due to the rapid development of traffic systems and increasing traffic all over the world. The accumulation of the heavy metals Pb, Cd, Cu and Zn in soils along the oldest federal highway of the world has been studied by sampling a roadside transect of 125 by 10 m. In addition, heavy metal concentrations of Pb, Cd, Zn, Cu, Ni and Cr in soil solutions from different distances (2.5, 5 and 10 m) from the hard shoulder of the highway and from three soil depths (10, 30, and 50 cm) were investigated. The results show that heavy metal concentrations are up to 20 times increased compared to the geochemical background levels and a reference site of 800-m distance from the roadside. Soil matrix concentrations in the topsoil (0-10 cm) mostly exceeded the precautionary values of the German Federal Soil Protection and Contamination Ordinance (BBodSchV). The concentrations of Cd, Pb and Zn in the soil matrix tended to decrease with distance from the roadside edge, whereas the concentrations in the soil solution increased at a distance of 10 m onwards due to a lower soil pH. Because of both high pH values and a high sorption capacity of the soils, soil solution concentrations seldom exceeded the trigger values of the German Federal Soil Protection and Contamination Ordinance (BBodSchV) for transferring soil solution to groundwater.

  11. Heavy metals in garden soils along roads in Szeged, Hungary

    NASA Astrophysics Data System (ADS)

    Szolnoki, Zsuzsanna; Farsang, Andrea

    2010-05-01

    The soils of the urban environment, owing to the various anthropogenic activities, can be contaminated by heavy metals. The traffic is well-known for more decades to be main source of heavy metals mostly in cities. The accumulation of these elements can have different effects, either directly endangering the natural soil functions, or indirectly endangering the biosphere by bio-accumulation and inclusion in the food chain. The hobby gardens and the vegetable gardens directly along roads can be potential risky for people since unknown amount of heavy metals can be accumulated into organization of local residents due to consumption of vegetables and fruits grown in their own garden. The aim of this study was to determine the heavy metal content of garden soils directly along roads with heavy traffic in order to assess possible risk for human health. The total content and the mobile content of Cd, Co, Cr, Cu, Ni, Pb and Zn have been determined in samples from garden soils along 5 busy roads of Szeged, South Hungary. Enrichment factor has been calculated with the help of control soil samples far from roads. The soil properties basically influencing on metal mobility have also been examined. Finally, the human health risk of these garden soils has been modelled by determination of health risk quotient (HRQ). As a result of our investigations, it can be claimed that mostly Cu, Zn and to a lesser degree the Ni, Cr and Pb accumulated in garden soils along roads depending on the traffic density. In general, the topsoils (0-10 cm) had higher amount of these metals rather than the subsoils (40-50 cm). Ni of these metals has approached; Cu has exceeded limit value while Pb is under it. Cd is very high in both soils along roads and control ones far from roads. Garden soils along the roads have such basic soil parameters (pH, mechanical soil type, humus content) that prove fairly high metal-binding capacity for these soils. Total risk of usage of these gardens (ingestion of soil

  12. The nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their amorphous thin films

    NASA Astrophysics Data System (ADS)

    Karatay, Ahmet; Aksoy, Çagla; Gul Yaglioglu, H.; Elmali, Ayhan; Kürüm, Ulaş; Ateş, Aytunç; Gasanly, Nizami

    2011-07-01

    We investigated the nonlinear and saturable absorption characteristics of Ga0.90In0.10Se and Ga0.85In0.15Se semiconductor crystals and their very thin amorphous films by open aperture (OA) Z-scan and pump-probe techniques. The linear absorption spectra indicated a blue shift in energy with increasing film thickness. This can be attributed to the quantum confinement effect. For both 4 ns and 65 ps pulse durations the two photon absorption coefficients of Ga0.90In0.10Se and Ga0.85In0.15Se crystals increased with increasing input intensities. The life time of the localized defect states was measured as 3 ns for both Ga0.90In0.10Se and Ga0.85In0.15Se films while it was around 10 ns for GaSe and InSe films. Open aperture Z-scan experiments with a 4 ns pulse duration did not exhibit any saturable absorption behavior for thin films since the life time of localized defect states was not long enough to saturate these films. Thinner films exhibited saturable absorption and thicker films exhibited nonlinear absorption for a 65 ps pulse duration. This behavior was attributed to increasing localized defect states with increasing film thickness. The experimental curves were fitted to the theory of the open aperture Gaussian-beam Z-scan based on the Adomian decomposition method incorporating one photon, two photon, and free carrier absorptions and their saturations. The lowest saturation intensity threshold for the Ga0.90In0.10Se film was found to be 1.38 × 102 MW cm - 2 for 43 nm film thickness.

  13. [Spatial variation characteristics of surface soil water content, bulk density and saturated hydraulic conductivity on Karst slopes].

    PubMed

    Zhang, Chuan; Chen, Hong-Song; Zhang, Wei; Nie, Yun-Peng; Ye, Ying-Ying; Wang, Ke-Lin

    2014-06-01

    Surface soil water-physical properties play a decisive role in the dynamics of deep soil water. Knowledge of their spatial variation is helpful in understanding the processes of rainfall infiltration and runoff generation, which will contribute to the reasonable utilization of soil water resources in mountainous areas. Based on a grid sampling scheme (10 m x 10 m) and geostatistical methods, this paper aimed to study the spatial variability of surface (0-10 cm) soil water content, soil bulk density and saturated hydraulic conductivity on a typical shrub slope (90 m x 120 m, projected length) in Karst area of northwest Guangxi, southwest China. The results showed that the surface soil water content, bulk density and saturated hydraulic conductivity had different spatial dependence and spatial structure. Sample variogram of the soil water content was fitted well by Gaussian models with the nugget effect, while soil bulk density and saturated hydraulic conductivity were fitted well by exponential models with the nugget effect. Variability of soil water content showed strong spatial dependence, while the soil bulk density and saturated hydraulic conductivity showed moderate spatial dependence. The spatial ranges of the soil water content and saturated hydraulic conductivity were small, while that of the soil bulk density was much bigger. In general, the soil water content increased with the increase of altitude while it was opposite for the soil bulk densi- ty. However, the soil saturated hydraulic conductivity had a random distribution of large amounts of small patches, showing high spatial heterogeneity. Soil water content negatively (P < 0.01) correlated with the bulk density and saturated hydraulic conductivity, while there was no significant correlation between the soil bulk density and saturated hydraulic conductivity.

  14. [Distribution characteristics of soil organic carbon under different forest restoration modes on opencast coal mine dump].

    PubMed

    Wen, Yue-rong; Dang, Ting-hui; Tang, Jun; Li, Jun-chao

    2016-01-01

    The content and storage of soil organic carbon (SOC) were compared in six wood restoration modes and adjacent abandoned land on opencast coal mine dump, and the mechanisms behind the differences and their influencing factors were analyzed. Results showed that the contents of SOC in six wood lands were significantly higher (23.8%-53.2%) than that of abandoned land (1.92 g · kg⁻¹) at 0-10 cm soil depth, the index were significantly higher (5.8%-70.4%) at 10-20 cm soil depth than the abandoned land (1.39 g · kg⁻¹), and then the difference of the contents of SOC in the deep soil (20-100 cm) were not significant. The contents of SOC decreased with increase of soil depth, but the decreasing magnitude of the topsoil (0-20 cm) was higher than that of the deep soil (20-100 cm). Compared with the deep soil, the topsoil significant higer storage of SOC in different woods, the SOC storage decreased with the soil depth. Along the 0-100 cm soil layer, the storage of SOC in six wood lands higher (18.1%-42.4%) than that of the abandoned land (17.52 t · hm⁻²). The SOC storage of Amorpha fruticosa land (24.95 t · hm⁻²) was obviously higher than that in the other wood lands. The SOC storage in the shrub lands was 12.4% higher than that of the arbor woods. There were significantly positive correlations among forest litter, fine root biomass, soil water content and SOC on the dump. Consequently, different plantation restorations significantly improved the SOC level on the dump in 0-100 cm soil, especially the topsoil. But there was still a big gap about SOC level between the wood restoration lands and the original landform. To improve the SOC on opencast coal mine dump, A. fruticosa could be selected as the main wood vegetation.

  15. Water movement through an experimental soil liner

    USGS Publications Warehouse

    Krapac, I.G.; Cartwright, K.; Panno, S.V.; Hensel, B.R.; Rehfeldt, K.R.; Herzog, B.L.

    1991-01-01

    break through at the base of the liner occurs. Estimated saturated hydraulic conductivities were 2.5 ?? 10-9, 4.0 ?? 10-8, and 5.0 ?? 10-8 cm s-1 based on measurements of water infiltration into the liner by large- and small-ring infiltrometers and a water balance analysis, respectively. Also investigated in this research was the variability of the liner's hydraulic properties and estimates of the transit times for water and tracers. Small variances exhibited by small-ring flux data suggested that the liner was homogeneous with respect to infiltration fluxes. The predictions of water and tracer breakthrough at the base of the liner ranged from 2.4-12.6 y, depending on the method of calculation and assumptions made. The liner appeared to be saturated to a depth between 18 and 33 cm at the end of the first year of monitoring. Transit time calculations cannot be verified yet, since breakthrough has not occurred. The work conducted so far indicates that compacted soil barriers can be constructed to meet the saturated hydraulic conductivity requirement established by the U.S. EPA.

  16. [Cutaneous Melanoma (CM): Current Diagnosis and Treatment].

    PubMed

    Gallegos Hernández, José Francisco; Nieweg, Omgo E

    2014-12-01

    Cutaneous melanoma (CM) is the third most common cancer of the skin, but it is the neoplasia with the greatest impact on mortality. Its etiology is multifactorial and it has been reported that its prevalence has increased in the last two decades. In Mexico, CM ranks seventh in frequency among all malignancies and 80% of cases are in locally advanced stages. The prognosis depends on the stage. The prognostic factors with greatest impact in survival are nodal status, tumor thickness or Breslow depth, ulceration, and in thin melanomas (< 1 mm thickness, without ulceration and Clarck level III), the mitotic index. The diagnostic approach is of great importance to achieve adequate treatment. Adherence to global guidelines of treatment allows us to obtain the best rates of locoregional control, which is the first target to be achieved in patients with CM. The goal of this manuscript is to provide a synthesis of the most important aspects in the diagnosis and treatment of CM, based on current evidence obtained in the literature.

  17. Neutron Resonance Parameters for Cm-242 (Curium)

    NASA Astrophysics Data System (ADS)

    Sukhoruchkin, S. I.; Soroko, Z. N.

    This document is part of the Supplement containing the complete sets of data of Volume 24 `Neutron Resonance Parameters' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It provides the neutron resonance parameters for the isotope Cm-242 (Curium).

  18. Applied K fertilizer use efficiency in pineapples grown on a tropical peat soil under residues removal.

    PubMed

    Ahmed, Osumanu H; Ahmad, Husni M H; Musa, Hanafi M; Rahim, Anuar A; Rastan, Syed Omar S

    2005-01-21

    In Malaysia, pineapples are grown on peat soils, but most K fertilizer recommendations do not take into account K loss through leaching. The objective of this study was to determine applied K use efficiency under a conventionally recommended fertilization regime in pineapple cultivation with residues removal. Results showed that K recovery from applied K fertilizer in pineapple cultivation on tropical peat soil was low, estimated at 28%. At a depth of 0-10 cm, there was a sharp decrease of soil total K, exchangeable K, and soil solution K days after planting (DAP) for plots with K fertilizer. This decline continued until the end of the study. Soil total, exchangeable, and solution K at the end of the study were generally lower than prior values before the study. There was no significant accumulation of K at depths of 10-25 and 25-45 cm. However, K concentrations throughout the study period were generally lower or equal to their initial status in the soil indicating leaching of the applied K and partly explained the low K recovery. Potassium losses through leaching in pineapple cultivation on tropical peat soils need to be considered in fertilizer recommendations for efficient recovery of applied K.

  19. Metals distribution in soils around the cement factory in southern Jordan.

    PubMed

    Al-Khashman, Omar A; Shawabkeh, Reyad A

    2006-04-01

    Thirty one soil samples were collected from south Jordan around the cement factory in Qadissiya area. The samples were obtained at two depths, 0-10 cm and 10-20 cm and were analyzed by atomic absorption spectrophotometery for Pb, Zn, Cd, Fe, Cu and Cr. Physicochemical factors believed to affect their mobility of metals in soil of the study area were examined such as; pH, TOM, CaCO3, CEC and conductivity. The relatively high concentrations of lead, zinc and cadmium in the soil samples of the investigated area were related to anthropogenic sources such as cement industry, agriculture activities and traffic emissions. It was found that the lead, zinc and cadmium have the highest level in area close to the cement factory, while the concentration of chromium was low. This study indicate that all of the metals are concentrated on the surface soil, and decreased in the lower part of the soil, this due to reflects their mobility and physical properties of soil and its alkaline pH values. The use of factor analysis showed that anthropogenic activities seem to be the responsible source of pollution for metals in urban soils.

  20. Anomalous RR Lyrae stars(?): CM Leonis

    NASA Astrophysics Data System (ADS)

    Di Fabrizio, L.; Clementini, G.; Marconi, M.; Carretta, E.; Ivans, I. I.; Bragaglia, A.; Di Tomaso, S.; Merighi, R.; Smith, H. A.; Sneden, C.; Tosi, M.

    2002-11-01

    Time-series of B, V, I CCD photometry and radial velocity measurements from high-resolution spectroscopy (R= 30 000) covering the full pulsation cycle are presented for the field RR Lyrae star CM Leonis. The photometric data span a 6-yr interval from 1994 to 1999, and allow us to firmly establish the pulsation mode and periodicity of the variable. The derived period P= 0.361 699 d (+/-0.000001) is very close to the value published in the Fourth Edition of the General Catalogue of Variable Stars (P= 0.361 732 d). However, contrary to what was previously found, the amplitude and shape of the light curve qualify CM Leo as a very regular first overtone pulsator with a prominent hump on the rising branch of its multicolour light curves. According to an abundace analysis performed on three spectra taken near minimum light (0.42 < φ < 0.61), CM Leo is a metal-poor star with metal abundance [Fe/H]=-1.93 +/- 0.20. The photometric and radial velocity curves of CM Leo have been compared with the predictions of suitable pulsational models to infer tight constraints on the stellar mass, effective temperature, and distance modulus of the star. We derive a true distance modulus of CM Leo of μ0= 13.11 +/- 0.02 mag and a corresponding absolute magnitude of MV= 0.47 +/- 0.04. This absolute magnitude, once corrected for evolutionary and metallicity effects, leads to a true distance modulus of the Large Magellanic Cloud of μ0= 18.43 +/- 0.06 mag, in better agreement with the long astronomical distance scale.

  1. Towards the 1-cm SARAL orbit

    NASA Astrophysics Data System (ADS)

    Zelensky, Nikita P.; Lemoine, Frank G.; Chinn, Douglas S.; Beckley, Brian D.; Bordyugov, Oleg; Yang, Xu; Wimert, Jesse; Pavlis, Despina

    2016-12-01

    We have investigated the quality of precise orbits for the SARAL altimeter satellite using Satellite Laser Ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) data from March 14, 2013 to August 10, 2014. We have identified a 4.31 ± 0.14 cm error in the Z (cross-track) direction that defines the center-of-mass of the SARAL satellite in the spacecraft coordinate system, and we have tuned the SLR and DORIS tracking point offsets. After these changes, we reduce the average RMS of the SLR residuals for seven-day arcs from 1.85 to 1.38 cm. We tuned the non-conservative force model for SARAL, reducing the amplitude of the daily adjusted empirical accelerations by eight percent. We find that the best dynamic orbits show altimeter crossover residuals of 5.524 cm over cycles 7-15. Our analysis offers a unique illustration that high-elevation SLR residuals will not necessarily provide an accurate estimate of radial error at the 1-cm level, and that other supporting orbit tests are necessary for a better estimate. Through the application of improved models for handling time-variable gravity, the use of reduced-dynamic orbits, and through an arc-by-arc estimation of the C22 and S22 coefficients, we find from analysis of independent SLR residuals and other tests that we achieve 1.1-1.2 cm radial orbit accuracies for SARAL. The limiting errors stem from the inadequacy of the DPOD2008 and SLRF2008 station complements, and inadequacies in radiation force modeling, especially with respect to spacecraft self-shadowing and modeling of thermal variations due to eclipses.

  2. 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.

  3. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    NASA Astrophysics Data System (ADS)

    Golos, Peter

    2016-04-01

    collected at >10 cm depth than the control. Mean soil pH at 0-10 cm was higher (>7.2) at all sites treated with lime compared to uncontaminated soil (5.5). At depths greater than 10 cm soil pH was <4.6. Soil copper was >16 mg/kg in all contaminated soil samples compared to 0.5 mg/kg in control. High seedling mortality in contaminated site is attributed to low soil pH and elevated soil copper levels which inhibited plant root growth and hence access to soil water. While surface liming of soil increased soil pH ameliorating the effect of elevated soil copper, this was only effective in the top 10 cm due to low solubility of hydrated lime. To improve seedling survival lime will need to be incorporated into the contaminated soil profile to allow plants to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context. To improve the success of vegetation restoration of sites contaminated with acidic copper solution, lime needs to be incorporated into the contaminated soil profile to allow plant roots to access soil water at depth. This study highlights the importance of the need to assess the phytotoxic effects of soil contamination and the effectiveness of amelioration treatments and with proper reference to its ecological context.

  4. Measurements of Output Factors For Small Photon Fields Up to 10 cm x 10 cm

    NASA Astrophysics Data System (ADS)

    Bacala, Angelina

    Field output factors (OF) for photon beams from a 6 MV medical accelerator were measured using five different detectors in a scanning water phantom. The measurements were taken for square field sizes of integral widths ranging from 1 cm to 10 cm for two reference source-to-surface distances (SSD) and depths in water. For the diode detectors, square field widths as small as 2.5 mm were also studied. The photon beams were collimated by using either the jaws or the multileaf collimators. Measured OFs are found to depend upon the field size, SSD, depth and also upon the type of beam collimation, size and type of detector used. For field sizes larger than 3 cm x 3 cm, the OF measurements agree to within 1% or less. The largest variation in OF occurs for jawsshaped field of size 1 cm x 1cm, where a difference of more than 18% is observed.

  5. Geostatistical analysis of soil moisture distribution in a part of Solani River catchment

    NASA Astrophysics Data System (ADS)

    Kumar, Kamal; Arora, M. K.; Hariprasad, K. S.

    2016-03-01

    The aim of this paper is to estimate soil moisture at spatial level by applying geostatistical techniques on the point observations of soil moisture in parts of Solani River catchment in Haridwar district of India. Undisturbed soil samples were collected at 69 locations with soil core sampler at a depth of 0-10 cm from the soil surface. Out of these, discrete soil moisture observations at 49 locations were used to generate a spatial soil moisture distribution map of the region. Two geostatistical techniques, namely, moving average and kriging, were adopted. Root mean square error (RMSE) between observed and estimated soil moisture at remaining 20 locations was determined to assess the accuracy of the estimated soil moisture. Both techniques resulted in low RMSE at small limiting distance, which increased with the increase in the limiting distance. The root mean square error varied from 7.42 to 9.77 in moving average method, while in case of kriging it varied from 7.33 to 9.99 indicating similar performance of the two techniques.

  6. Design of a soil cutting resistance sensor for application in site-specific tillage.

    PubMed

    Agüera, Juan; Carballido, Jacob; Gil, Jesús; Gliever, Chris J; Perez-Ruiz, Manuel

    2013-05-10

    One objective of precision agriculture is to provide accurate information about soil and crop properties to optimize the management of agricultural inputs to meet site-specific needs. This paper describes the development of a sensor equipped with RTK-GPS technology that continuously and efficiently measures soil cutting resistance at various depths while traversing the field. Laboratory and preliminary field tests verified the accuracy of this prototype soil strength sensor. The data obtained using a hand-operated soil cone penetrometer was used to evaluate this field soil compaction depth profile sensor. To date, this sensor has only been tested in one field under one gravimetric water content condition. This field test revealed that the relationships between the soil strength profile sensor (SSPS) cutting force and soil cone index values are assumed to be quadratic for the various depths considered: 0-10, 10-20 and 20-30 cm (r2 = 0.58, 0.45 and 0.54, respectively). Soil resistance contour maps illustrated its practical value. The developed sensor provides accurate, timely and affordable information on soil properties to optimize resources and improve agricultural economy.

  7. Interpreting Sky-Averaged 21-cm Measurements

    NASA Astrophysics Data System (ADS)

    Mirocha, Jordan

    2015-01-01

    Within the first ~billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this epoch of reionization -- the emergence of the first stars, black holes (BHs), and full-fledged galaxies -- are expected to manifest themselves as extrema in sky-averaged ("global") measurements of the redshifted 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) modeling required to make robust predictions.I have developed numerical models that efficiently solve the frequency-dependent radiative transfer equation, which has led to two advances in studies of the global 21-cm signal. First, frequency-dependent solutions facilitate studies of how the global 21-cm signal may be used to constrain the detailed spectral properties of the first stars, BHs, and galaxies, rather than just the timing of their formation. And second, the speed of these calculations allows one to search vast expanses of a currently unconstrained parameter space, while simultaneously characterizing the degeneracies between parameters of interest. I find principally that (1) physical properties of the IGM, such as its temperature and ionization state, can be constrained robustly from observations of the global 21-cm signal without invoking models for the astrophysical sources themselves, (2) translating IGM properties to galaxy properties is challenging, in large part due to frequency-dependent effects. For instance, evolution in the characteristic spectrum of accreting BHs can modify the 21-cm absorption signal at levels accessible to first generation instruments, but could easily be confused with evolution in the X-ray luminosity star-formation rate relation. Finally, (3) the independent constraints most likely to aide in the interpretation

  8. Data Simulation for 21 cm Cosmology Experiments

    NASA Astrophysics Data System (ADS)

    Pober, Jonathan

    2017-01-01

    21 cm cosmologists seek a measurement of the hyperfine line of neutral hydrogen from very high redshifts. While this signal has the potential to provide an unprecedented view into the early universe, it is also buried under exceedingly bright foreground emission. Over the last several years, 21 cm cosmology research has led to an improved understanding of how low frequency radio interferometers will affect the separation of cosmological signal from foregrounds. This talk will describe new efforts to incorporate this understanding into simulations of the most realistic data sets for the Precision Array for Probing the Epoch of Reionization (PAPER), the Murchison Widefield Array (MWA), and the Hydrogen Epoch of Reionization Array (HERA). These high fidelity simulations are essential for robust algorithm design and validation of early results from these experiments.

  9. Extended Performance 8-cm Mercury Ion Thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.

    1981-01-01

    A slightly modified 8-cm Hg ion thruster demonstrated significant increase in performance. Thrust was increased by almost a factor of five over that of the baseline thruster. Thruster operation with various three grid ion optics configurations; thruster performance as a function of accelerator grid open area, cathode baffle, and cathode orifice size; and a life test of 614 hours at a beam current of 250 mA (17.5 mN thrust) are discussed. Highest thruster efficiency was obtained with the smallest open area accelerator grid. The benefits in efficiency from the low neutral loss grids were mitigated, however, by the limitation such grids place on attainable ion beam current densities. The thruster components suffered negligible weight losses during a life test, which indicated that operation of the 8-cm thruster at extended levels of thrust and power is possible with no significant loss of lifetime.

  10. 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.

  11. 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.

  12. 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.

  13. Soil Physical Characteristics and Biological Indicators of Soil Quality Under Different Biodegradable Mulches

    NASA Astrophysics Data System (ADS)

    Schaeffer, S. M.; Flury, M.; Sintim, H.; Bandopadhyay, S.; Ghimire, S.; Bary, A.; DeBruyn, J.

    2015-12-01

    Application of conventional polyethylene (PE) mulch in crop production offers benefits of increased water use efficiency, weed control, management of certain plant diseases, and maintenance of a micro-climate conducive for plant growth. These factors improve crop yield and quality, but PE must be retrieved and safely disposed of after usage. Substituting PE with biodegradable plastic mulches (BDM) would alleviate disposal needs, and is potentially a more sustainable practice. However, knowledge of potential impacts of BDMs on agricultural soil ecosystems is needed to evaluate sustainability. We (a) monitored soil moisture and temperature dynamics, and (b) assessed soil quality upon usage of different mulches, with pie pumpkin (Cucurbita pepo) as the test crop. Experimental field trials are ongoing at two sites, one at Northwestern Washington Research and Extension Center, Mount Vernon, WA, and the other at East Tennessee Research and Education Center, Knoxville, TN. The treatments constitute four different commercial BDM products, one experimental BDM; no mulch and PE served as the controls. Soil quality parameters being examined include: organic matter content, aggregate stability, water infiltration rate, CO2 flux, pH, and extracellular enzyme activity. In addition, lysimeters were installed to examine the soil water and heat flow dynamics. We present baseline and the first field season results from this study. Mulch cover appeared to moderate soil temperatures, but biodegradable mulches also appeared to lose water more quickly than PE. All mulch types, with the exception of cellulose, reduced the diurnal fluctuations in soil temperature at 10cm depth from 1 to 4ºC. However, volumetric water content ranged from 0.10 to 0.22 m3 m-3 under the five biodegradable mulches compared to 0.22 to 0.28 m3 m-3 under conventional PE. Results from the study will be useful for management practices by providing knowledge on how different mulches impact soil physical and

  14. Impacts of land use changes on physical and chemical soil properties in the Central Pyrenees

    NASA Astrophysics Data System (ADS)

    Nadal Romero, Estela; Hoitinga, Leo; Valdivielso, Sergio; Pérez Cardiel, Estela; Serrano Muela, Pili; Lasanta, Teodoro; Cammeraat, Erik

    2015-04-01

    Soils and vegetation tend to evolve jointly in relation to climate evolution and the impacts of human activity. Afforestation has been one of the main policies for environmental management of forest landscapes in Mediterranean areas. Afforestation has been based mainly on conifers because they are fast-growing species, and also because it was believed that this would lead to rapid restoration of soil properties and hydrological processes, and the formation of protective vegetation cover. This study analyses the effects of afforestation on physical and chemical soil properties. Specifically, we addressed this research question: (i) How do soil properties change after land abandonment? The 11 microsites considered were: Afforestation Pinus sylvestris (escarpment, terrace and close to the stem), Afforestation Pinus nigra (escarpment, terrace and close to the stem), natural shrubland, grasslands, bare lands, and undisturbed forest site (pine cover and close to the stem). An extensive single sampling was carried out in September 2014. We systematically collected 5 top soil samples (0-10 cm) and 3 deep soil samples (10-20 cm) per microsite (88 composite samples in total). These properties were analysed: (i) soil texture, (ii) bulk density, (iii) pH and electrical conductivity, (iv) total SOC, (v) Total Nitrogen, (vi) organic matter, (vii) CaCO3 and (viii) aggregate stability. Statistical tests have been applied to determine relationships between the different soil properties and are used to assess differences between different soil samples, land use areas and soil depths. Implications of reafforestation for soil development and environmental response are discussed. Acknowledgments This research was supported by a Marie Curie Intra-European Fellowship in the project "MED-AFFOREST" (PIEF-GA-2013-624974).

  15. Does distance from the sea affect a soil microarthropod community?

    NASA Astrophysics Data System (ADS)

    Wasserstrom, Haggai; Steinberger, Yosef

    2016-10-01

    Coastal sand dunes are dynamic ecosystems characterized by strong abiotic gradients from the seashore inland. Due to significant differences in the abiotic parameters in such an environment, there is great interest in biotic adaptation in these habitats. The aim of the present study, which was conducted in the northern Sharon sand-dune area of Israel, was to illustrate the spatial changes of a soil microarthropod community along a gradient from the seashore inland. Soil samples were collected from the 0-10 cm depth at five locations at different distances, from the seashore inland. Samples were taken from the bare open spaces during the wet winter and dry summer seasons. The soil microarthropod community exhibited dependence both on seasonality and sampling location across the gradient. The community was more abundant during the wet winter seasons, with an increasing trend from the shore inland, while during the dry summers, such a trend was not observed and community density was lower. The dominant groups within soil Acari were Prostigmata and Endeostigmata, groups known to have many representatives with adaptation to xeric or psammic environments. In addition, mite diversity tended to be higher at the more distant locations from the seashore, and lower at the closer locations, a trend that appeared only during the wet winters. This study demonstrated the heterogeneity of a soil microarthropod community in a coastal dune field in a Mediterranean ecosystem, indicating that the gradient abiotic parameters also affect the abundance and composition of a soil microarthropod community in sand dunes.

  16. [Application of ICP-MS in evaluating element contamination in soils].

    PubMed

    Wu, Ying-juan; Chen, Yong-heng; Yang, Chun-xia; Chang, Xiang-yang

    2008-12-01

    The Yunfu pyrite was the second biggest pyrite bed in the world. Plants using industrial ore of the Yunfu pyrite are distributed in many sections across the country. In the present paper, elements V, Cr, Co, Cu, Zn, Mo, Cd, Sb, Rb and Cs in soil profiles in slag disposing area of a sulfuric acid plant using industrial ore of theYunfu pyrite were studied. A method for simultaneously determination of metals and some reference elements in soils by ICP-MS was developed. The correlations between the metals and their reference elements were fast found. Enrichment factors were applied for evaluating the degree of soil contamination, and the problem about choosing contamination elements background values was pointed out. The results indicated that element V showed apparent and serious pollution, The Co showed middle degree pollution, and there has been a trend of apparent pollution. The Cr, Mo and Cd showed pollution between light degree and middle degree. The Zn and Sb showed light degree pollution, and there was a latent trend of middle degree pollution. The Cu showed light degree pollution. The high enrichment points of the V and the Cr were observed in the upper part (4.0-10.5 cm) and deep part of soil profiles (44.0-75.5 cm). Those of Co and Mo were found in the surface of soil profiles (0-5.0 cm), middle-upper part (9.5-10.5 cm) and middle part (29.5-46.0 cm), while those of Cd and Cu occurred just in the middle of soil profiles (29.5-46.0 cm). The formation of highly enrichment points of contamination elements in the soil profiles was the result of leaching and accumulating effect of the metals released from slag and the residual metals of highly weathered red soils. Most of pollution of V in the soil was contributed by the V in soil bed. Part of the V pollution in the soil was supplied by leaching and accumulating effect of the V which came from catalyst with lost activity in sulfuric acid production volatilizing into slag.

  17. 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

  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.

  19. Agricultural use of soil, consequences in soil organic matter and hydraulic conductivity compared with natural vegetation in central Spain

    NASA Astrophysics Data System (ADS)

    Vega, Verónica; Carral, Pilar; Alvarez, Ana Maria; Marques, Maria Jose

    2014-05-01

    When ecosystems are under pressure due to high temperatures and water scarcity, the use of land for agriculture can be a handicap for soil and water conservation. The interactions between plants and soils are site-specific. This study provides information about the influence of the preence vs. The absence of vegetation on soil in a semi-arid area of the sout-east of Madrid (Spain, in the Tagus River basin. In this area soil materials are developed over a calcareous-evaporitic lithology. Soils can be classified as Calcisols, having horizons of accumulation with powdered limestone and irregular nodules of calcium carbonate. They can be defined as Haplic Cambisols and Leptic Calcisols (WRB 2006-FAO). The area is mainly used for rainfed agriculture, olive groves, vineyards and cereals. There are some patches of bushes (Quercus sp.) and grasses (Stipa tenacissima L.) although only found on the top of the hills. This study analyses the differences found in soils having three different covers: Quercus coccifera, Stipa tenacissima and lack of vegetation. This last condition was found in the areas between cultivated olive trees. Soil organic matter, porosity and hydraulic conductivity are key properties of soil to understand its ability to adapt to climate or land use changes. In order to measure the influence of different soil covers, four replicates of soil were sampled in each condition at two soil depth, (0-10 cm and 10-20 cm). Hydraulic conductivity was measured in each soil condition and replicate using a Mini-disk® infiltrometer. There were no differences between the two depths sampled. Similarly, there were no changes in electric conductivity (average 0.1±0.03 dS m-1); pH (8.7±0.2) or calcium carbonate content (43±20 %). Nevertheless, significant differences (p>0.001) were found in soil organic matter. The maximum was found in soils under Quercus (4.7±0.5 %), followed by Stipa (2.2±1.1 %). The soil without vegetation in the areas between olive trees had only 0

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Carbon amendment and soil depth affect the distribution and abundance of denitrifiers in agricultural soils.

    PubMed

    Barrett, M; Khalil, M I; Jahangir, M M R; Lee, C; Cardenas, L M; Collins, G; Richards, K G; O'Flaherty, V

    2016-04-01

    The nitrite reductase (nirS and nirK) and nitrous oxide reductase-encoding (nosZ) genes of denitrifying populations present in an agricultural grassland soil were quantified using real-time polymerase chain reaction (PCR) assays. Samples from three separate pedological depths at the chosen site were investigated: horizon A (0-10 cm), horizon B (45-55 cm), and horizon C (120-130 cm). The effect of carbon addition (treatment 1, control; treatment 2, glucose-C; treatment 3, dissolved organic carbon (DOC)) on denitrifier gene abundance and N2O and N2 fluxes was determined. In general, denitrifier abundance correlated well with flux measurements; nirS was positively correlated with N2O, and nosZ was positively correlated with N2 (P < 0.03). Denitrifier gene copy concentrations per gram of soil (GCC) varied in response to carbon type amendment (P < 0.01). Denitrifier GCCs were high (ca. 10(7)) and the bac:nirK, bac:nirS, bac:nir (T) , and bac:nosZ ratios were low (ca. 10(-1)/10) in horizon A in all three respective treatments. Glucose-C amendment favored partial denitrification, resulting in higher nir abundance and higher N2O fluxes compared to the control. DOC amendment, by contrast, resulted in relatively higher nosZ abundance and N2 emissions, thus favoring complete denitrification. We also noted soil depth directly affected bacterial, archaeal, and denitrifier abundance, possibly due to changes in soil carbon availability with depth.

  8. Design study of large area 8 cm x 8 cm wrapthrough cells for space station

    NASA Technical Reports Server (NTRS)

    Garlick, George F. J.; Lillington, David R.

    1987-01-01

    The design of large area silicon solar cells for the projected NASA space station is discussed. It is based on the NASA specification for the cells which calls for an 8 cm by 8 cm cell of wrapthrough type with gridded back contacts. The beginning of life (BOL) power must be 1.039 watts per cell or larger and maximum end of life (EOL) after 10 years in the prescribed orbit under an equivalent 1MeV electron radiation damage fluence of 5 times 10 to the 13th power e/square cm. On orbit efficiency is to be optimized by a low thermal absorptance goal (thermal alpha) of .63.

  9. Aliphatic Amines in Antarctic CR2, CM2, and CM1/2 Carbonaceous Chondrites

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

    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 delta13C 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 delta13C 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 delta13C values of methylamine in CR2 chondrites ranged from -1 to +10per mille, while in CM2 and CM1/2 chondrites the delta13C values of methylamine ranged from +41 to +59per mille. 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 delta13C 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.

  10. 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.

  11. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil.

    PubMed

    Banning, Natasha C; Maccarone, Linda D; Fisk, Louise M; Murphy, Daniel V

    2015-06-08

    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

  12. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil

    NASA Astrophysics Data System (ADS)

    Banning, Natasha C.; Maccarone, Linda D.; Fisk, Louise M.; Murphy, Daniel V.

    2015-06-01

    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

  13. Mapping physical properties of Swiss forest soils by robust external-drift kriging from legacy soil data

    NASA Astrophysics Data System (ADS)

    Papritz, Andreas; Ramirez Lopez, Leo; Baltensweiler, Andri; Walthert, Lorenz

    2015-04-01

    Climate change scenario predict for Switzerland increasing summer temperature and decreasing precipitation. In coming decades forests will therefore likely experience more often drought. However, it is not clear to what extent these changes will occur and where in Switzerland they will be most pronounced. Soil-Vegetation-Atmosphere-Transfer (SVAT) models allow to explore likely changes in the water regime of forest under changing climate. Such process models require information of soil physical properties that largely control water storage in forest soils. Spatial information on physical properties of forest soils is currently lacking in Switzerland. Therefore one objective of the project "Soils and water regime of Swiss forests and forest sites under present and future climate BOWA-CH" (http://www.wsl.ch/fe/boden/projekte/bowa_ch/index_EN) was to predict basic physical properties of forest soils at high spatial resolution for the whole Swiss territory. Based on legacy data of about 2000 forest soil profiles, we mapped particle size composition, volumetric content of rock fragments, soil organic carbon (SOC) content and soil density for fixed-depth soil layers (0-10, 10-30, 30-60, ..., 120-150 cm) by robust external drift kriging (Nussbaum et al., 2014). Comprehensive, digitally available information on climate, topography, vegetation and geology were used as covariates for statistical modelling. Preliminary sets of covariates were chosen by LASSO, and the selection was refined by cross-validating the model for the external drift. External validation with 20 % of the data revealed that clay and sand content, soil density and SOC could be predicted with acceptable precision. Predictions of rock fragment content and silt content were less precise, and the developed model failed to spatially predict soil depth. This is unfortunate because soil depth and rock fragment content largely control water storage in soils. Nussbaum, M., Papritz, A., Baltensweiler, A

  14. Phosphorus in Soils of a Cool-desert Ecosystem: Dust Inputs and Land-use Effects on Erosion, Colorado Plateau, USA.

    NASA Astrophysics Data System (ADS)

    Sanford, R. L.; Reheis, M.; Hanson-Gonzalez, K.; Reynolds, R.

    2001-12-01

    Phosphorus (P) contents indicate that aeolian dust is supplying P to soils and vegetation in the Colorado Plateau. We determined P fractions for dust inputs, surface soils, and bedrock at Canyonlands N.P., Utah. Measurement sites were chosen on the basis of livestock grazing history; one site has never been grazed, another site had grazing until 30 years ago, and a third site is grazed currently. Using a modified Hedley sequential fractionation, we partitioned dust, soils, and bedrock into biological and geochemical pools, as well as labile and refractory pools. At the never-grazed site, total P in surface soil (0-10 cm) is half that of dust, whereas total P in bedrock samples is only one third that of dust. The contrast is more striking for labile P and biological P; modern dust samples have 6x and 9x more, respectively, than soil samples. Resin extractable P as a proportion of labile P in dust may be a useful indicator of grazing perturbance. Dust from the currently grazed site has most total P (1551 ugP/g soil), followed by dust from the previously grazed site (1120 ugP/g soil), and by dust from the never-grazed site (737 ugP/g soil), suggesting wind erosion of P. Slope transects on grazed vs. ungrazed surfaces suggest that P and other plant nutrients have been eroded from grazed upper slopes, because near-surface samples (0-10 cm depth) show increases in these elements downslope, whereas deeper samples (30-50 cm) show little change.

  15. Winter effect on soil microorganisms under different tillage and phosphorus management practices in eastern Canada.

    PubMed

    Shi, Yichao; Lalande, Roger; Hamel, Chantal; Ziadi, Noura

    2015-05-01

    Determining how soil microorganisms respond to crop management systems during winter could further our understanding of soil phosphorus (P) transformations. This study assessed the effects of tillage (moldboard plowing or no-till) and P fertilization (0, 17.5, or 35 kg P·ha(-1)) on soil microbial biomass, enzymatic activity, and microbial community structure in winter, in a long-term (18 years) corn (Zea mays L.) and soybean (Glycine max L.) rotation established in 1992 in the province of Quebec, Canada. Soil samples were collected at 2 depths (0-10 and 10-20 cm) in February 2010 and 2011 after the soybean and the corn growing seasons, respectively. Winter conditions increased the amounts of soil microbial biomasses but reduced the overall enzymatic activity of the soil, as compared with fall levels after corn. P fertilization had a quadratic effect on the amounts of total, bacterial, arbuscular mycorrhizal fungi phospholipid fatty acid markers after corn but not after soybean. The soil microbial community following the soybean and the corn crops in winter had a different structure. These findings suggest that winter conditions and crop-year could be important factors affecting the characteristics of the soil microbial community under different tillage and mineral P fertilization.

  16. The effects of the Qinghai-Tibet railway on heavy metals enrichment in soils.

    PubMed

    Zhang, Hua; Wang, Zhaofeng; Zhang, Yili; Hu, Zhongjun

    2012-11-15

    The impact of land transportation on local soil environments is an important topic in environmental and ecological sciences. The rapid development of transportation infrastructure lends increasing importance to studies that identify and evaluate related heavy metal pollution. This paper discusses the effects of railways on soil heavy metal enrichments in the Tibetan plateau. At a representative area along the Haergai-Delingha railway, lead, cadmium, copper, zinc, chromium, nickel, cobalt, and vanadium were measured in 127 topsoil samples (0-10 cm depth). The results indicate that railway transport has a significant effect on the concentration of Zn, Cd and Pb in the soil, with levels of enrichment ranging from no pollution to significant pollution. The affected area was within 20 m of the railway. The soil at Delingha was the most contaminated soil with heavy metals, and the enrichment level of Cd in the soil was the highest along the Qinghai-Tibet railway. The horizontal distributions of the three heavy metals present different characteristics at different sampling sites, which may be due to discrepancies in terrain and vegetation types. Alkaline soils and guardrails along the railway might reduce the effect of soil pollution on local people and animals.

  17. Tillage system affects microbiological properties of soil

    NASA Astrophysics Data System (ADS)

    Delgado, A.; de Santiago, A.; Avilés, M.; Perea, F.

    2012-04-01

    Shannon (H') and Gini (1-G) diversity index of microbial communities were determined in soil samples (0-10 cm depth) taken in autumn 2009. All the enzymatic activities and the biomass estimated by viable cell counting were significantly higher under no-till than under conventional tillage. However, only fluorescents pseudomonas population was increased under no-till, meanwhile oligotrophic bacteria and actinomycetes populations were higher with conventional tillage than with no-till. Overall, there was a higher use all the group of carbon sources used in the BiologR test with conventional tillage than with no-till, by except amines and phenols which showed non-significant differences. This reveals different physiological profiles in the microbial communities under both tillage systems. The Gini diversity was significantly lower with no-till than with conventional tillage. It can be concluded that no-till increases microbial biomass in soil and subsequently enzymatic activities likely ascribed to an increased organic matter content. Under low availability of hydrocarbon sources in soil due to conventional tillage, which promotes a decrease in the organic matter content of the soil, populations of oligotrophods and the diversity of microbial communities are increased. Under these conditions, there must not be dominant carbon sources promoting the selection of microorganisms with a given physiological profile. The reduced hydrocarbon availability and the higher diversity contribute to explain the increased use of carbon sources used in Biolog with conventional tillage than with no-till.

  18. [Effects of different straw-returning regimes on soil organic carbon and carbon pool management index in Guanzhong Plain, Northwest China].

    PubMed

    Li, Shuo; Li, You-bing; Wang, Shu-juan; Shi, Jiang-lan; Tian, Xiao-hong

    2015-04-01

    A four-year (2008-2012) field experiment was conducted to investigate the effects of different straw-returning regimes on soil total organic carbon (TOC), labile organic carbon (LOC) and the ratio of LOC to TOC (LOC/TOC) as well as TOC stock (SCS) and soil carbon pool management index (CPMI) in a farmland with maize-wheat double cropping system in Guanzhong Plain area, Shaanxi Province, China. The results indicated that soil TOC and LOC contents and SCS were significantly increased when wheat or maize straw was returned to field, and the increasing extent showed the rising order as follows: double straw-returning > single straw-returning > no straw-returning. Compared to no straw returning, a significant increase of TOC and LOC contents and SCS was found in the treatment of wheat straw chopping retention combined with maize straw chopping subsoiling retention (WC-MM), and CPMI of WC-MM was significantly higher than in the other treatments in 0-20 cm soil layer. Compared to no wheat straw returning, soil CPMIs in 0-10 cm and 10-20 cm soil layer increased by 19.1% and 67.9% for the wheat straw chopping returning treatment, and by 22.6% and 32.4% for the maize straw chopping subsoiling treatment, respectively. Correlation analysis showed that soil CPMI was a more effective index reflecting the sequestration of soil organic carbon in 0-30 cm soil layer than the ratio of LOC to TOC. This study thus suggested that WC-MM regime is the best straw-returning regime for soil organic carbon sequestration.

  19. How deep does disturbance go? The long-term effects of canopy disturbance on tropical forest soil biogeochemistry

    NASA Astrophysics Data System (ADS)

    Gutiérrez del Arroyo, O.; Silver, W. L.

    2015-12-01

    We used the Canopy Trimming Experiment (CTE), an ongoing ecosystem manipulation study in the Luquillo Experimental Forest (LEF), Puerto Rico to determine the decadal-scale effects of canopy disturbance and debris deposition on biogeochemistry throughout the soil profile of a wet tropical forest. These manipulations represent the most significant effects of hurricanes, which may increase in frequency or intensity with warming, strengthening their ecosystem-level effects on carbon (C) and nutrient cycling. Four replicated treatments were applied in 2005 using a complete randomized block design: canopy trimming + debris deposition, canopy trimming only, debris deposition only, and untreated control. In 2015, we sampled soils at 10 cm intervals to 1 m depth in each of 12 plots (3 per treatment). We measured gravimetric moisture content, pH, HCl and citrate-ascorbate (CA) extractable iron (Fe) species, organic (Po) and inorganic fractions of NaHCO3 and NaOH phosphorus (P), as well as total C and nitrogen (N). Soil moisture decreased markedly with depth up to ~60-70 cm, and then stabilized at ~33% down to 1 m. Across all treatments, pH increased significantly with depth, ranging from 4.6 in surface soils (0-10 cm) of trimmed plots to 5.2 in deep soils (80-90 cm) of control plots. Canopy trimming decreased pH significantly, possibly due to increased root activity in surface soils as vegetation recovered. Both HCl and CA extractable Fe showed strong depth dependance, decreasing linearly to 50 cm, and stabilizing at very low concentrations (<0.2 mg/g) down to 1 m. Inorganic P concentrations were low and did not vary significantly with depth. The majority of P was associated with organic matter, with significantly higher values in the upper soil profile (<50 cm). Debris deposition significantly increased Po, revealing the role of hurricanes in subsidizing the available soil P pool in these highly productive, low-P wet tropical forests. Debris deposition also increased soil C

  20. 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.

  1. High temperature x-ray diffraction studies on antiferroelectric and ferroelectric phase transitions in (Pb1-xBax)ZrO3 (x=0.05,0.10)

    NASA Astrophysics Data System (ADS)

    Pokharel, Bhadra P.; Pandey, Dhananjai

    2001-09-01

    We have carried out high temperature x-ray diffraction studies on (Pb1-xBax)ZrO3(PBZ) to correlate the large thermal hysteresis (˜100 °C for x=0.05) and irreversibility (for x=0.10) of the antiferroelectric (AFE)-ferroelectric (FE) phase transition observed in dielectric measurements with structural changes. It is shown that for both the compositions, the sequence of phase transitions during heating is orthorhombic antiferroelectric (AO) to rhombohedral ferroelectric (FR) and then to cubic paraelectric (PC). The wide phase coexistence region (˜80 °C for x=0.05 and ˜160 °C for x=0.10) and the arrest of the FR to AO transition for x=0.10 during cooling strongly indicate first order character of the AO-FR transition. It is shown that the transformation strains associated with the AO to FR transition increases with Ba2+ concentration from a value of 0.6% for x=0 to 0.9% for 0.10. Similarities of the AO-FR transition in PBZ with nonthermoelastic martensitic transformations are pointed out. The FR to PC transition is also shown to be first order but with a small thermal hysteresis (˜10 °C) and a small discontinuous change in the cell volume (˜0.5%).

  2. 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

  3. Cycling Stability Performance of La0.75Mg0.25Ni3.5Si0.10 Hydrogen Storage Alloy in Discharge-Charge System

    NASA Astrophysics Data System (ADS)

    Liu, Zhaojiang; Huang, Lei; Wan, Qi; Li, Xu; Guang, Ma; Li, Ping

    2014-12-01

    La0.75Mg0.25Ni3.5Si0.10 hydrogen storage alloy was prepared by vacuum induction melting furnace and subsequently heated treatment at 940°C for 8 h and cooled to room temperature in the oven. The electrochemical properties of La0.75Mg0.25Ni3.5Si0.10 compound were measured by LAND CT2001A battery test system. The morphologies of the samples were characterized by scanning electron microscopy (SEM). The surface state of samples was analyzed by X-ray photoelectron spectroscopy (XPS). It was found that the charge-discharge rate plays the key impact on the cycling stability of the alloy. During the cycle test, the prepared La0.75Mg0.25Ni3.5Si0.10 compound presented an excellent capacity retention at the charge-discharge of 1 C while the capacity of sample declined rapidly at 0.2 C. The excellent cycling stability performance of La0.75Mg0.25Ni3.5Si0.10 electrode at 1 C could be attributed to the less powder and less oxidation of surface effective active elements. The pulverization inevitably leads to the separation of the part of the cracking alloy and the electrode, resulting in reduction of the effective active substance and increasing attenuation of the capacity per cycle. In addition, on the analysis of the different cut-off potential effects on the electrode, it was found that the La0.75Mg0.25Ni3.5Si0.10 electrode shows good comprehensive electrochemical properties at 1 C cut-off 0.6-0.7 V. During charging, heavy overcharge will not be conducive to cycling stability performance during the charging test.

  4. Nano-hydroxyapatite alleviates the detrimental effects of heavy metals on plant growth and soil microbes in e-waste-contaminated soil.

    PubMed

    Wei, Liu; Wang, Shutao; Zuo, Qingqing; Liang, Shuxuan; Shen, Shigang; Zhao, Chunxia

    2016-06-15

    The crude recycling activities of e-waste have led to the severe and complex contamination of e-waste workshop topsoil (0-10 cm) by heavy metals. After nano-hydroxyapatite (NHAp) application in June 2013, plant and soil samples were obtained in November 2013, December 2013, March 2014 and June 2014. The results showed that NHAp effectively reduced the concentration of CaCl2-extractable Pb, Cu, Cd, and Zn in the topsoil and significantly reduced the metal content in ryegrass and also increased the plant biomass compared with that of the control. Moreover, the concentrations of CaCl2-extractable metals in the soil decreased with increasing NHAp. NHAp application also increased the activities of soil urease, phosphatase and dehydrogenase. Moreover, the soil bacterial diversity and community structure were also altered after NHAp application. Particularly, Stenotrophomonas sp. and Bacteroides percentages were increased. Our work proves that NHAp application can alleviate the detrimental effects of heavy metals on plants grown in e-waste-contaminated soil and soil enzyme activities, as well as soil microbial diversity.

  5. Disruption of the naturally evolved N conservation strategy in soil under grassland at a sports field in York, UK.

    PubMed

    Bhatti, Ambreen; Cresser, Malcolm S

    2014-11-01

    Water- and KCl-extractable ammonium-N and nitrate-N concentrations have been monitored at approximately monthly intervals over a year in soils from 0-10 and 10-20 cm depths under permanent grass at a sports field in York, UK. Measurements were made on both fresh, field-moist soils and after the same soils had been incubated for 7 days at ambient outdoor temperatures, to assess seasonal changes in the capacity of the soils to produce mineral-N species in the absence of plant uptake and other effects. Water extracts allowed potential mobility of N species to be assessed. Comparison of seasonal trends in mineral-N species concentrations in pre- and post-incubation soils confirmed depletion of exchangeable ammonium-N from the winter to summer. Mineral-N in fresh and incubated soils displayed summer minima and also low production in winter, associated with the effects of low temperature on nitrate production and probably microbial immobilization of nitrate produced by residual senescent plant litter with a higher C:N ratio from the previous autumn. The results support the concept that plant/soil systems co-evolved under more pristine conditions to conserve soil N by matching the dynamics of soil mineral N production and plant N uptake, but now N pollution has resulted in a dynamic mismatch.

  6. Age of respired carbon in differently managed grassland and forest soils

    NASA Astrophysics Data System (ADS)

    Schoening, Ingo; Trumbore, Susan; Solly, Emily; Muhr, Jan; Schrumpf, Marion

    2013-04-01

    Grassland management (fertilization, grazing, mowing) and forest management (harvesting, thinning) directly affect biomass production and related leaf and root litter input to the soil. Understanding effects of land management on soil carbon fluxes is therefore critical. We examined the effect of land use and management on soil respiration and the age of respired soil carbon. Soil samples originated from grassland and forest plots in three different German regions. Sieved surface soil samples (0-10 cm) were incubated (20°C, 60% WHC) for 14 days. The respired CO2 was collected and 14C contents in the CO2 of 150 incubated samples were determined with accelerator mass spectrometry (AMS). Large changes recorded in 14C in the atmosphere since atmospheric weapons testing in the 1960s allow precise determination of the mean age of emitted soil carbon. In our study, the rate of respiration was higher in grassland soils (33 ± 10 µg C-CO2 per g dry soil per day) compared to forest soils (14 ± 7 µg C-CO2 per g dry soil per day). Results indicate a strong relation between respiration rates and grassland management with lower soil respiration in more fertilized plots. This relation was not found at sites where degraded peatlands were used as grasslands. At those sites, respiration rates were mainly driven by the soil organic carbon concentration. In forest soils, we did not find any relation between soil respiration and forest management. The 14C contents of the respired CO2 were lower in grassland soils (Percentage Modern carbon content: 104±2%) compared to forest soils (Percentage Modern Carbon content: 108±5%). This indicates that the carbon respired in forests is generally several years to more than a decade older than the carbon respired in grasslands. In grasslands, the 14C is positively related to the respiration rate and negatively related to fertilization. Again, degraded peat soils, where old carbon is released during incubation, were the exception to this

  7. [Effects of different re-vegetation patterns on soil organic carbon and total nitrogen in the wind-water erosion crisscross region, China].

    PubMed

    Liu, Xue-tong; Wei, Yan-chun; Yang, Xian-long; Hao, Ming-de; Wei, Xiao-rong

    2016-01-01

    This study was conducted to analyze the responses of soil organic carbon (SOC) and total nitrogen (TN) to three typical re-vegetation patterns, i.e., grassland, alfalfa land and peashrub land on the Loess Plateau of China, and also to assess the dynamics of SOC and TN with re-vegetation age. The results showed that all the three re-vegetation practices increased the concentrations of SOC and TN in the 0-10 cm soil layer, but their effects differed with re-vegetation age. Compared with adjacent croplands, the concentrations of SOC and TN in the 0-10 cm soil layer in grassland did not change within 10 years of succession, but increased after 20 years of succession. In alfalfa land, the concentrations of SOC and TN increased by 51.6%-82.9% and 43.4%-67.0% in the 0-10 cm soil layer, with the increasing rates of stocks of SOC and TN being 0.17-0.46 and 0.015-0.043 t · hm⁻² · a⁻¹, respectively. However, SOC and TN were not affected by re-vegetation age in alfalfa land. The increases of concentrations of SOC and TN remained high in the first 20 years after conversion of cropland to peashrub land, but decreased after 40 years of conversion. In conclusion, the conversion of croplands to peashrub or alfalfa land could be better in contributing to high stocks of SOC and TN than natural succession of grassland. However, their positive effects on the enrichment of SOC and TN may not be sustainable due to the scarcity of soil moisture and high water consumption of these two re-vegetation plants.

  8. 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.

  9. 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.

  10. Temporal changes in chlorantraniliprole and indoxacarb in four midwestern soils and bioefficacy against the eastern subterranean termite (Isoptera: Rhinotermitidae).

    PubMed

    Spomer, Neil A; Kamble, Shripat T

    2011-06-01

    Temporal changes in indoxacarb and chlorantraniliprole were determined in four midwestern soils by simulating commercial field applications of termiticides. Indoxacarb (0.0625 and 0.125%) and chlorantraniliprole (0.05 and 0.10%) were applied to each soil type in a rotating cement mixer to ensure uniform distribution of active ingredient (AI). Temporal and spatial changes in termiticide concentrations were determined by sampling soil cores subdivided at different depths (0-20, 20-40, and 40-61 cm) at various intervals up to 705 d after application. Percentage loss of indoxacarb was initially greater (0-180 d) than losses after 180 d. The lowest indoxacarb extractable concentrations were detected in soils closest to the surface. Chlorantraniliprole losses with time from all soils were slower than indoxacarb, with no differences observed with soil type or depth. Bioefficacy was evaluated in laboratory glass tube bioassays that monitored the distance of termite penetration into treated soils and resulting eastern subterranean termite, Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae), worker mortality. Bioassay data revealed that R. flavipes termites were unable to completely penetrate 50 mm of indoxacarb- and chlorantraniliprole treated soils at 0 d after treatment; however, termites were not deterred from foraging in these soils indicating no repellency to these termiticides. Termites completely penetrated (50 mm) soils treated with indoxacarb (0.0625%) by 360 d and complete penetration occurred in all soils treated with indoxacarb (0.0625 and 0.125%) by 705 d. Termites were unable to completely penetrate chlorantraniliprole-treated soils at 705 d. Mortality of termite workers was high in all chlorantraniliprole-treated soils at all sampling intervals. These data confirm that vertical differences in termiticide persistence occur in various soils.

  11. Permafrost Thaw, Soil Moisture and Plant Community Change Alter Organic Matter Decomposition in Alaskan Tundra

    NASA Astrophysics Data System (ADS)

    Natali, S.; Mauritz, M.; Pegoraro, E.; Schuur, E.

    2015-12-01

    Climate warming in arctic tundra has been associated with increased plant productivity and a shift in plant community composition, specifically an increase in shrub cover, which can impact soil organic matter through changes in the size and composition of the leaf litter pool. Shifts in litter quantity and quality will in turn interact with changes in the soil environment as the climate continues to warm. We examined the effects of permafrost thaw, soil moisture changes, and plant community composition on leaf litter decomposition in an upland tundra ecosystem in Interior Alaska. We present warming and drying effects on decomposition rates of graminoid-dominated and shrub-dominated leaf litter mixtures over three years (2 cm depth), and annual decomposition of a common cellulose substrate (0-10 cm and 10-20 cm) over five years at a permafrost thaw and soil drying experiment. We expected that warming and drying would increase decomposition, and that decomposition would be greater in the shrub litter than in the graminoid litter mix. Decomposition of Betula nana, the dominant shrub, was 50% greater in the shrub-dominated litter mix compared to the graminoid-dominated litter. Surprisingly, there was no significant difference in total litter mass loss between graminoid and shrub litter mixtures, despite significant differences in decomposition rates of the dominant plant species when decomposed alone and in community mixtures. Drying decreased decomposition of B. nana and of the shrub community litter overall, but after two years there was no detected warming effect on shrub-community decomposition. In contrast to leaf litter decomposition, both warming and drying increased decomposition of the common substrate. Warming caused an almost twofold increase in cellulose decomposition in surface soil (0-10cm), and drying caused a twofold increase in cellulose decomposition from deeper organic layer soils (10-20cm). These results demonstrate the importance of interactions

  12. Measuring and modeling ammonium adsorption by calcareous soils.

    PubMed

    Ranjbar, F; Jalali, M

    2013-04-01

    The aim of this study was assessment of ammonium (NH 4(+) ) adsorption isotherms in some agricultural calcareous soils and modeling of that by using the mechanistic exchange model. Ten surface soils (0-30 cm) were collected from areas covered with different land uses in Hamedan, western Iran. Isotherm experiments were carried out by concentrations of NH 4(+) prepared from NH4Cl salt (0, 10, 20, 30, 40, 50, 100, and 150 mg NH 4(+)  l(-1)) in presence of 0.01 M CaCl2 solution. The empirical models including simple adsorption isotherm and Freundlich equations were fitted well to the experimental data. The average amounts of adsorbed NH 4(+) in studied soils varied from 8.95 to 35.23 %. Adsorption percentage indicated positive correlation with pH, cation-exchange capacity (CEC), equivalent calcium carbonate, and clay content and had negative correlation with sand content. In order to predict and model NH 4(+) adsorption, cation-exchange model in PHREEQC program was used. The model could simulate the NH 4(+) adsorption very well in all studied soils. The values of CEC played the major role in modeling of NH 4(+) adsorption in this study indicating that cation-exchange process was the major mechanism controlling NH 4(+) adsorption in studied soils.

  13. Research on the infiltration processes of lawn soils of the Babao River in the Qilian Mountain.

    PubMed

    Li, GuangWen; Feng, Qi; Zhang, FuPing; Cheng, AiFang

    2014-01-01

    Using a Guelph Permeameter, the soil water infiltration processes were analyzed in the Babao River of the Qilian Mountain in China. The results showed that the average soil initial infiltration and the steady infiltration rates in the upstream reaches of the Babao River are 1.93 and 0.99 cm/min, whereas those of the middle area are 0.48 cm/min and 0.21 cm/min, respectively. The infiltration processes can be divided into three stages: the rapidly changing stage (0-10 min), the slowly changing stage (10-30 min) and the stabilization stage (after 30 min). We used field data collected from lawn soils and evaluated the performances of the infiltration models of Philip, Kostiakov and Horton with the sum of squared error, the root mean square error, the coefficient of determination, the mean error, the model efficiency and Willmott's index of agreement. The results indicated that the Kostiakov model was most suitable for studying the infiltration process in the alpine lawn soils.

  14. Vertical distribution of nitrite-dependent anaerobic methane-oxidising bacteria in natural freshwater wetland soils.

    PubMed

    Shen, Li-dong; Huang, Qian; He, Zhan-fei; Lian, Xu; Liu, Shuai; He, Yun-feng; Lou, Li-ping; Xu, Xiang-yang; Zheng, Ping; Hu, Bao-lan

    2015-01-01

    Nitrite-dependent anaerobic methane oxidation (n-damo) is a recently discovered process that is catalysed by "Candidatus Methylomirabilis oxyfera". In the present study, the vertical distribution (0-10, 20-30, 50-60 and 90-100 cm) of M. oxyfera-like bacteria was investigated in Xiazhuhu wetland, the largest natural wetland on the southern Yangtze River (China). Phylogenetic analyses showed that group A of M. oxyfera-like bacteria and pmoA genes occurred primarily at depths of 50-60 and 90-100 cm. Quantitative PCR further confirmed the presence of M. oxyfera-like bacteria in soil cores from different depths, with the highest abundance of 5.1 × 10(7) copies g(-1) dry soil at depth of 50-60 cm. Stable isotope experiments demonstrated that the n-damo process occurred primarily at depths of 50-60 and 90-100 cm, with the potential rates ranging from 0.2 to 14.5 nmol CO2 g(-1) dry soil d(-1). It was estimated that the methane flux may increase by approximately 2.7-4.3% in the examined wetland in the absence of n-damo. This study shows that the deep wetland soils (50-60 and 90-100 cm) are the preferred habitats for M. oxyfera-like bacteria. The study also highlights the potential importance of these bacteria in the methane and nitrogen cycles in deep wetland soils.

  15. Pressure distributions obtained on a 0.10-scale model of the space shuttle Orbiter's forebody in the AEDC 16T propulsion wind tunnel

    NASA Technical Reports Server (NTRS)

    Siemers, P. M., III; Henry, M. W.

    1986-01-01

    Pressure distribution test data obtained on a 0.10-scale model of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests were completed in the AEDC 16T Propulsion Wind Tunnel. The 0.10-scale model was tested at angles of attack from -2 deg to 18 deg and angles of side slip from -6 to 6 deg at Mach numbers from 0.25 to 1/5 deg. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS orifices, the wind-tunnel model was also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations that existed on the Space Shuttle Orbiter Columbia (OV-102) during the Orbiter Flight Test program. This DFI simulation has provided a means of comparisons between reentry flight pressure data and wind-tunnel and computational data.

  16. [Characteristics of the wetland soil iron under different ages of reclamation].

    PubMed

    Zou, Yuan-Chun; Lü, Xian-Guo; Jiang, Ming

    2008-03-01

    The temporal-spatial trends of soil total iron concentration (Fet), free degree (Fed/Fet), activation degree (Feo/Fed) and complex degree (Fep/Fed) of soil iron oxides after reclamation were studied in Sanjiang Plain Wetlands. The result suggests that Fet in the upper tillage layers (0 - 20 cm) are influenced by reclamation more significantly than that in the lower ones (20 - 100 cm), and so does the early ages (0 - 1 years) than the late ages (1 - 25 years). Fet is negatively correlated with organic matter extremely significantly (R = - 0.62), while that with total phosphorus and pH are not significant. Fet of soil layer I (0 - 10 cm) increases obviously during the first 7 years after reclamation, and tends to become stable after 13 years, while those ages of soil layer II (10 - 20 cm) are 8 years and 15 years respectively. Soil layer I shows shorter responding time and better regularity than layer II. Fed/Fet increases rapidly after reclamation, decreases later and then increases again. Feo/Fed indicates exponential decrease with the reclamation ages as well as Fep/Fed. Feo/Fed of layer I decreases radically during the first 4 years after reclamation and tends to become stable after 13 years, while that of layer II decreases dramatically within the first year and keeps stable henceforth. The counterparts of Fep/Fed are 6 years, 14 years, and 2 years respectively. With the fitted experimental equations of Fet, Feo/Fed, and Fep/Fed, the ages of reclamation can be deduced reversely, which indicates the implication of iron on the shifts of soil environment.

  17. Sorption of acetochlor, S-metolachlor, and atrazine in surface and subsurface soil horizons of Argentina.

    PubMed

    Bedmar, Francisco; Daniel, Peter E; Costa, José L; Giménez, Daniel

    2011-09-01

    Understanding herbicide sorption within soil profiles is the first step to predicting their behavior and leaching potential. Laboratory studies were conducted to determine the influence of surface and subsurface soil properties on acetochlor, atrazine, and S-metolachlor sorption. Soil samples were taken from horizons A, B, and C of two loamy soils of the humid pampas of Argentina under no-till management; horizon A was divided into two layers, A(0) (0-5 cm) and A(1) (5 cm to the full thickness of an A horizon). Sorption isotherms were determined from each sampled horizon using the batch equilibrium method and seven concentrations (0, 0.1, 0.5, 2.0, 5.0, 10.0, and 20.0 mg L(-1)). Sorption affinity of herbicides was approximated by the Freundlich equation. The sorption strength K(f) (mg(1 - 1/n) kg(-1) L(1/n) ) over the soils and horizons studied followed the order S-metolachlor (16.51-29.19) > atrazine (4.85-12.34) ≥ acetochlor (5.17-11.97), which was closely related to the hydrophobicity of herbicides expressed as octanol-water partition coefficient (K(OW) ). The K(f) values of the three herbicides were positively correlated with soil organic carbon, with a significance of p < 0.01. Values of K(f) for the three herbicides decreased with depth in the two soils, indicating greater sorption onto surficial soil horizons and possibly a delayed transport toward subsurface soils and subsequent pollution of groundwater.

  18. Particulate Organic Matter Responses to Perennial Grass Production in Midwestern Soil

    NASA Astrophysics Data System (ADS)

    Kantola, I. B.; Masters, M. D.; DeLucia, E. H.

    2015-12-01

    Terrestrial carbon sequestration is essential to mitigating atmospheric carbon dioxide levels. While annual row crop agriculture contributes to soil carbon loss in the Midwest, the establishment of perennial crops has the potential to increase soil carbon stocks through increased organic inputs and changes soil carbon pools and fluxes. Perennial grasses eliminate the need for tillage and increase belowground biomass, both critical to the conservation of soil organic matter and soil carbon sequestration. The effect of C4 perennial grasses on particulate organic matter (POM) was evaluated in Illinois, where native switchgrass and a sterile hybrid of the Asian grass Miscanthus were planted at the University of Illinois Energy Farm in 2008. During 6 years after establishment of perennial crops, POM was compared with plots growing a corn-corn-soy rotation typical of the area and a 26-species restored prairie. POM concentrations increased for all crops between 67 and 79% over 6 years, with the greatest increases in prairie and miscanthus soils. POM concentrations were highest at the 0-10 cm depth, however POM accrued faster in the 10-30 cm depth. Isotopic analyses of POM material showed that after 6 years, POM carbon consisted of 22-33% C4 material under perennial monoculture crops, indicating the incorporation of newly-established plant material to the POM fraction. As POM carbon is primarily plant-derived, increases in POM reflect increases in organic matter inputs as well as the cessation of tillage. While increases in POM under annual row crops reflect the incorporation of aboveground organic matter by tillage, POM increases in untilled perennial crops mirror increases in belowground biomass and the formation large soil aggregates, structures which protect POM carbon from microbial degradation and result in longer residence times for soil carbon. Therefore untilled soils under long-term perennial crop production provide an important environment for the storage and

  19. Ecosystem development after mangrove wetland creation: plant-soil change across a 20-year chronosequence

    USGS Publications Warehouse

    Osland, Michael J.; Spivak, Amanda C.; Nestlerode, Janet A.; Lessmann, Jeannine M.; Almario, Alejandro E.; Heitmuller, Paul T.; Russell, Marc J.; Krauss, Ken W.; Alvarez, Federico; Dantin, Darrin D.; Harvey, James E.; From, Andrew S.; Cormier, Nicole; Stagg, Camille L.

    2012-01-01

    Mangrove wetland restoration and creation efforts are increasingly proposed as mechanisms to compensate for mangrove wetland losses. However, ecosystem development and functional equivalence in restored and created mangrove wetlands are poorly understood. We compared a 20-year chronosequence of created tidal wetland sites in Tampa Bay, Florida (USA) to natural reference mangrove wetlands. Across the chronosequence, our sites represent the succession from salt marsh to mangrove forest communities. Our results identify important soil and plant structural differences between the created and natural reference wetland sites; however, they also depict a positive developmental trajectory for the created wetland sites that reflects tightly coupled plant-soil development. Because upland soils and/or dredge spoils were used to create the new mangrove habitats, the soils at younger created sites and at lower depths (10-30 cm) had higher bulk densities, higher sand content, lower soil organic matter (SOM), lower total carbon (TC), and lower total nitrogen (TN) than did natural reference wetland soils. However, in the upper soil layer (0-10 cm), SOM, TC, and TN increased with created wetland site age simultaneously with mangrove forest growth. The rate of created wetland soil C accumulation was comparable to literature values for natural mangrove wetlands. Notably, the time to equivalence for the upper soil layer of created mangrove wetlands appears to be faster than for many other wetland ecosystem types. Collectively, our findings characterize the rate and trajectory of above- and below-ground changes associated with ecosystem development in created mangrove wetlands; this is valuable information for environmental managers planning to sustain existing mangrove wetlands or mitigate for mangrove wetland losses.

  20. Accuracy of free energies of hydration using CM1 and CM3 atomic charges.

    PubMed

    Udier-Blagović, Marina; Morales De Tirado, Patricia; Pearlman, Shoshannah A; Jorgensen, William L

    2004-08-01

    Absolute free energies of hydration (DeltaGhyd) have been computed for 25 diverse organic molecules using partial atomic charges derived from AM1 and PM3 wave functions via the CM1 and CM3 procedures of Cramer, Truhlar, and coworkers. Comparisons are made with results using charges fit to the electrostatic potential surface (EPS) from ab initio 6-31G* wave functions and from the OPLS-AA force field. OPLS Lennard-Jones parameters for the organic molecules were used together with the TIP4P water model in Monte Carlo simulations with free energy perturbation theory. Absolute free energies of hydration were computed for OPLS united-atom and all-atom methane by annihilating the solutes in water and in the gas phase, and absolute DeltaGhyd values for all other molecules were computed via transformation to one of these references. Optimal charge scaling factors were determined by minimizing the unsigned average error between experimental and calculated hydration free energies. The PM3-based charge models do not lead to lower average errors than obtained with the EPS charges for the subset of 13 molecules in the original study. However, improvement is obtained by scaling the CM1A partial charges by 1.14 and the CM3A charges by 1.15, which leads to average errors of 1.0 and 1.1 kcal/mol for the full set of 25 molecules. The scaled CM1A charges also yield the best results for the hydration of amides including the E/Z free-energy difference for N-methylacetamide in water.

  1. Parameters of microbial respiration in soils of the impact zone of a mineral fertilizer factory

    NASA Astrophysics Data System (ADS)

    Zhukova, A. D.; Khomyakov, D. M.

    2015-08-01

    The carbon content in the microbial biomass and the microbial production of CO2 (the biological component of soil respiration) were determined in the upper layer (0-10 cm) of soils in the impact zone of the OJSC Voskresensk Mineral Fertilizers, one of the largest factories manufacturing mineral fertilizers in Russia. Statistical characteristics and schematic distribution of the biological parameters in the soil cover of the impact zone were analyzed. The degree of disturbance of microbial communities in the studied objects varied from weak to medium. The maximum value (0.44) was observed on the sampling plot 4 km away from the factory and 0.5 km away from the place of waste (phosphogypsum) storage. Significantly lower carbon content in the microbial biomass and its specific respiration were recorded in the agrosoddy-podzolic soil as compared with the alluvial soil sampled at the same distance from the plant. The effects of potential soil pollutants (fluorine, sulfur, cadmium, and stable strontium) on the characteristics of soil microbial communities were described with reliable regression equations.

  2. Human Health Risk Assessment of 16 Priority Polycyclic Aromatic Hydrocarbons in Soils of Chattanooga, Tennessee, USA

    PubMed Central

    Hussar, Erika; Richards, Sean; Lin, Zhi-Qing; Dixon, Robert P.; Johnson, Kevin A.

    2012-01-01

    South Chattanooga has been home to foundries, coke furnaces, chemical, wood preserving, tanning and textile plants for over 100 years. Most of the industries were in place before any significant development of residential property in the area. During the 1950s and 1960s, however, the government purchased inexpensive property and constructed public housing projects in South Chattanooga. Many neighborhoods that surround the Chattanooga Creek were previous dumping grounds for industry. Polycyclic aromatic hydrocarbons (PAHs) comprised the largest component of the dumping and airborne industrial emissions. To address the human exposure to these PAHs, a broad study of South Chattanooga soil contaminant concentrations was conducted on 20 sites across the city. Sixteen priority pollutant PAHs were quantified at two depths (0-10cm and 10-20cm) and compared against reference site soils, as well as to soils from industrially-impacted areas in Germany, China, and the US. From these data, the probability that people would encounter levels exceeding EPA Residential Preliminary Remediation Goals (PRG) was calculated. Results indicate that South Chattanooga soils have relatively high concentrations of total PAHs, specifically Benzo[a]pyrene (B[a]P). These high concentrations of B[a]P were somewhat ubiquitous in South Chattanooga. Indeed, there is a high probability (88%) of encountering soil in South Chattanooga that exceeds the EPA PRG for B[a]P. However, there is a low probability (15%) of encountering a site with ∑PAHs exceeding EPA PRG guidelines. PMID:23243323

  3. Environmental radioactivity study of Austrian and Bavarian forest ecosystems: Long- term behaviour of contamination of soil, vegetation and wild boar and its radioecological coherences.

    PubMed

    Kocadag, Maria; Exler, Veronika; Christopher, Burger-Scheidlin; Baumgartner, Andreas; Stietka, Michael; Landstetter, Claudia; Korner, Martin; Maringer, Franz Josef

    2017-03-18

    (137)Cs and (40)K in soil, vegetation and flesh of wild boar samples from Austrian and Bavarian regions were investigated by gamma-ray spectrometry and (90)Sr in bones of wild boar with Liquid Scintillation Counting (LSC) after radiochemical separation. The soil core profiles revealed that 70-97% of the soil caesium content is still accumulated in the 0-10cm soil depth. From all vegetation samples the mushrooms, particularly the bay boletus showed the highest (137)Cs contamination. The activity concentration of (137)Cs in muscle tissue of boar ranged from 14.9±1.5Bq/kg (Bavaria) to 4711±377Bq/kg (Lower Austria). In the bones of wild boars, (90)Sr activity concentration ranged from 1.4±0.2Bq/kg (Bavaria) to 70.3±10.5Bq/kg (Upper Austria).

  4. Spatial analysis of soil organic carbon in Zhifanggou catchment of the Loess Plateau.

    PubMed

    Li, Mingming; Zhang, Xingchang; Zhen, Qing; Han, Fengpeng

    2013-01-01

    Soil organic carbon (SOC) reflects soil quality and plays a critical role in soil protection, food safety, and global climate changes. This study involved grid sampling at different depths (6 layers) between 0 and 100 cm in a catchment. A total of 1282 soil samples were collected from 215 plots over 8.27 km(2). A combination of conventional analytical methods and geostatistical methods were used to analyze the data for spatial variability and soil carbon content patterns. The mean SOC content in the 1282 samples from the study field was 3.08 g · kg(-1). The SOC content of each layer decreased with increasing soil depth by a power function relationship. The SOC content of each layer was moderately variable and followed a lognormal distribution. The semi-variograms of the SOC contents of the six different layers were fit with the following models: exponential, spherical, exponential, Gaussian, exponential, and exponential, respectively. A moderate spatial dependence was observed in the 0-10 and 10-20 cm layers, which resulted from stochastic and structural factors. The spatial distribution of SOC content in the four layers between 20 and 100 cm exhibit were mainly restricted by structural factors. Correlations within each layer were observed between 234 and 562 m. A classical Kriging interpolation was used to directly visualize the spatial distribution of SOC in the catchment. The variability in spatial distribution was related to topography, land use type, and human activity. Finally, the vertical distribution of SOC decreased. Our results suggest that the ordinary Kriging interpolation can directly reveal the spatial distribution of SOC and the sample distance about this study is sufficient for interpolation or plotting. More research is needed, however, to clarify the spatial variability on the bigger scale and better understand the factors controlling spatial variability of soil carbon in the Loess Plateau region.

  5. Application of atomic force microscopy to the study of natural and model soil particles.

    PubMed

    Cheng, S; Bryant, R; Doerr, S H; Rhodri Williams, P; Wright, C J

    2008-09-01

    The structure and surface chemistry of soil particles has extensive impact on many bulk scale properties and processes of soil systems and consequently the environments that they support. There are a number of physiochemical mechanisms that operate at the nanoscale which affect the soil's capability to maintain native vegetation and crops; this includes soil hydrophobicity and the soil's capacity to hold water and nutrients. The present study used atomic force microscopy in a novel approach to provide unique insight into the nanoscale properties of natural soil particles that control the physiochemical interaction of material within the soil column. There have been few atomic force microscopy studies of soil, perhaps a reflection of the heterogeneous nature of the system. The present study adopted an imaging and force measurement research strategy that accounted for the heterogeneity and used model systems to aid interpretation. The surface roughness of natural soil particles increased with depth in the soil column a consequence of the attachment of organic material within the crevices of the soil particles. The roughness root mean square calculated from ten 25 microm(2) images for five different soil particles from a Netherlands soil was 53.0 nm, 68.0 nm, 92.2 nm and 106.4 nm for the respective soil depths of 0-10 cm, 10-20 cm, 20-30 cm and 30-40 cm. A novel analysis method of atomic force microscopy phase images based on phase angle distribution across a surface was used to interpret the nanoscale distribution of organic material attached to natural and model soil particles. Phase angle distributions obtained from phase images of model surfaces were found to be bimodal, indicating multiple layers of material, which changed with the concentration of adsorbed humic acid. Phase angle distributions obtained from phase images of natural soil particles indicated a trend of decreasing surface coverage with increasing depth in the soil column. This was consistent with

  6. New λ6 cm and λ11 cm observations of the supernova remnant CTA 1

    NASA Astrophysics Data System (ADS)

    Sun, X. H.; Reich, W.; Wang, C.; Han, J. L.; Reich, P.

    2011-11-01

    Aims: We attempt to study spatial variations in the spectrum and rotation measures (RMs) of the large-diameter, high-latitude supernova remnant (SNR) CTA 1. Methods: We conducted new λ6 cm and λ11 cm observations of CTA 1 using the Urumqi 25-m and Effelsberg 100-m telescopes. Data at other wavelengths were included to investigate the spectrum and polarisation properties. Results: We obtained new total intensity and polarisation maps at λ6 cm and λ11 cm with angular resolutions of 9'.5and 4'.4, respectively. We derived a spectral index of α = -0.63 ± 0.05 (Sν ∝ να) based on the integrated flux densities at 408 MHz, 1420 MHz, 2639 MHz, and 4800 MHz. The spectral index map calculated from data at the four frequencies shows a clear steepening of the spectrum from the strong shell emission towards the north-western breakout region with weak diffuse emission. The decrease of the spectral index is up to about Δα = 0.3. The RM map derived from polarisation data at λ6 cm and λ11 cm shows a sharp transition between positive RMs in the north-eastern and negative RMs in the south-western part of the SNR. We note a corresponding RM pattern of extragalactic sources and propose the existence of a large-diameter Faraday screen in front of CTA 1, which covers the north-eastern part of the SNR. The RM of the Faraday screen is estimated to be about +45 rad m-2. A RM structure function of CTA 1 indicates a very regular magnetic field within the Faraday screen, which is stronger than about 2.7 μG for a distance of 500 pc. Conclusions: CTA 1 is a large-diameter shell-type SNR located out of the Galactic plane, which makes it an ideal object to study its properties without suffering confusion. The previous detection of the rare breakout phenomenon in CTA 1 is confirmed. We identify a Faraday screen partly covering CTA 1 with a regular magnetic field in the opposite direction to the interstellar magnetic field. The detection of Faraday screens in the Galactic plane is

  7. Multi-Seasonal Nitrogen Recoveries from Crop Residue in Soil and Crop in a Temperate Agro-Ecosystem.

    PubMed

    Hu, Guoqing; Liu, Xiao; He, Hongbo; Zhang, Wei; Xie, Hongtu; Wu, Yeye; Cui, Jiehua; Sun, Ci; Zhang, Xudong

    2015-01-01

    In conservation tillage systems, at least 30% of the soil surface was covered by crop residues which generally contain significant amounts of nitrogen (N). However, little is known about the multi-seasonal recoveries of the N derived from these crop residues in soil-crop systems, notably in northeastern China. In a temperate agro-ecosystem, 15N-labeled maize residue was applied to field surfaces in the 1st year (2009). From the 2nd to 4th year (2010-2012), one treatment halted the application of maize residue, whereas the soil in the second treatment was re-applied with unlabeled maize residue. Crop and soil samples were collected after each harvest, and their 15N enrichments were determined on an isotope ratio mass spectrometer to trace the allocation of N derived from the initially applied maize residue in the soil-crop systems. On average, 8.4% of the maize residue N was recovered in the soil-crop in the 1st year, and the vast majority (61.9%-91.9%) was recovered during subsequent years. Throughout the experiment, the cumulative recovery of the residue N in the crop increased gradually (18.2%-20.9%), but most of the residue N was retained in the soil, notably in the 0-10 cm soil layer. Compared to the single application, the sequential residue application significantly increased the recovery of the residue N in the soil profile (73.8% vs. 40.9%) and remarkably decreased the total and the initially applied residue derived mineral N along the soil profile. Our results suggested that the residue N was actively involved in N cycling, and its release and recovery in crop and soil profile were controlled by the decomposition process. Sequential residue application significantly enhanced the retention and stabilization of the initially applied residue N in the soil and retarded its translocation along the soil profile.

  8. Multi-Seasonal Nitrogen Recoveries from Crop Residue in Soil and Crop in a Temperate Agro-Ecosystem

    PubMed Central

    Hu, Guoqing; Liu, Xiao; He, Hongbo; Zhang, Wei; Xie, Hongtu; Wu, Yeye; Cui, Jiehua; Sun, Ci; Zhang, Xudong

    2015-01-01

    In conservation tillage systems, at least 30% of the soil surface was covered by crop residues which generally contain significant amounts of nitrogen (N). However, little is known about the multi-seasonal recoveries of the N derived from these crop residues in soil-crop systems, notably in northeastern China. In a temperate agro-ecosystem, 15N-labeled maize residue was applied to field surfaces in the 1st year (2009). From the 2nd to 4th year (2010-2012), one treatment halted the application of maize residue, whereas the soil in the second treatment was re-applied with unlabeled maize residue. Crop and soil samples were collected after each harvest, and their 15N enrichments were determined on an isotope ratio mass spectrometer to trace the allocation of N derived from the initially applied maize residue in the soil-crop systems. On average, 8.4% of the maize residue N was recovered in the soil-crop in the 1st year, and the vast majority (61.9%-91.9%) was recovered during subsequent years. Throughout the experiment, the cumulative recovery of the residue N in the crop increased gradually (18.2%-20.9%), but most of the residue N was retained in the soil, notably in the 0-10 cm soil layer. Compared to the single application, the sequential residue application significantly increased the recovery of the residue N in the soil profile (73.8% vs. 40.9%) and remarkably decreased the total and the initially applied residue derived mineral N along the soil profile. Our results suggested that the residue N was actively involved in N cycling, and its release and recovery in crop and soil profile were controlled by the decomposition process. Sequential residue application significantly enhanced the retention and stabilization of the initially applied residue N in the soil and retarded its translocation along the soil profile. PMID:26192436

  9. Linking temperature sensitivity of soil CO2 release to substrate, environmental, and microbial properties across alpine ecosystems

    NASA Astrophysics Data System (ADS)

    Ding, Jinzhi; Chen, Leiyi; Zhang, Beibei; Liu, Li; Yang, Guibiao; Fang, Kai; Chen, Yongliang; Li, Fei; Kou, Dan; Ji, Chengjun; Luo, Yiqi; Yang, Yuanhe

    2016-09-01

    Our knowledge of fundamental drivers of the temperature sensitivity (Q10) of soil carbon dioxide (CO2) release is crucial for improving the predictability of soil carbon dynamics in Earth System Models. However, patterns and determinants of Q10 over a broad geographic scale are not fully understood, especially in alpine ecosystems. Here we addressed this issue by incubating surface soils (0-10 cm) obtained from 156 sites across Tibetan alpine grasslands. Q10 was estimated from the dynamics of the soil CO2 release rate under varying temperatures of 5-25°C. Structure equation modeling was performed to evaluate the relative importance of substrate, environmental, and microbial properties in regulating the soil CO2 release rate and Q10. Our results indicated that steppe soils had significantly lower CO2 release rates but higher Q10 than meadow soils. The combination of substrate properties and environmental variables could predict 52% of the variation in soil CO2 release rate across all grassland sites and explained 37% and 58% of the variation in Q10 across the steppe and meadow sites, respectively. Of these, precipitation was the best predictor of soil CO2 release rate. Basal microbial respiration rate (B) was the most important predictor of Q10 in steppe soils, whereas soil pH outweighed B as the major regulator in meadow soils. These results demonstrate that carbon quality and environmental variables coregulate Q10 across alpine ecosystems, implying that modelers can rely on the "carbon-quality temperature" hypothesis for estimating apparent temperature sensitivities, but relevant environmental factors, especially soil pH, should be considered in higher-productivity alpine regions.

  10. Spatial variability and stocks of soil organic carbon in the Gobi desert of Northwestern China.

    PubMed

    Zhang, Pingping; Shao, Ming'an

    2014-01-01

    Soil organic carbon (SOC) plays an important role in improving soil properties and the C global cycle. Limited attention, though, has been given to assessing the spatial patterns and stocks of SOC in desert ecosystems. In this study, we quantitatively evaluated the spatial variability of SOC and its influencing factors and estimated SOC storage in a region (40 km2) of the Gobi desert. SOC exhibited a log-normal depth distribution with means of 1.6, 1.5, 1.4, and 1.4 g kg(-1) for the 0-10, 10-20, 20-30, and 30-40 cm layers, respectively, and was moderately variable according to the coefficients of variation (37-42%). Variability of SOC increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. Significant correlations were detected between SOC and soil physical properties, i.e. stone, sand, silt, and clay contents and soil bulk density. The relatively coarse fractions, i.e. sand, silt, and stone contents, had the largest effects on SOC variability. Experimental semivariograms of SOC were best fitted by exponential models. Nugget-to-sill ratios indicated a strong spatial dependence for SOC concentrations at all depths in the study area. The surface layer (0-10 cm) had the largest spatial dependency compared with the other layers. The mapping revealed a decreasing trend of SOC concentrations from south to north across this region of the Gobi desert, with higher levels close to an oasis and lower levels surrounded by mountains and near the desert. SOC density to depths of 20 and 40 cm for this 40 km2 area was estimated at 0.42 and 0.68 kg C m(-2), respectively. This study provides an important contribution to understanding the role of the Gobi desert in the global carbon cycle.

  11. [Soil organic carbon and nitrogen mineralization along a forest successional gradient in Southern China].

    PubMed

    Ouyang, Xue-Jun; Zhou, Guo-Yi; Wei, Shi-Guang; Huang, Zhong-Liang; Li, Jiong; Zhang, De-Qiang

    2007-08-01

    With incubation test, this paper studied the characteristics of organic C and N mineralization in 0-10 cm soil layer under three forest types, i. e., pine (Pinus massoniana) forest (PMF), pine and broad-leaved mixed forest (PBMF) and monsoon evergreen broad-leaved forest (MEBF), which were in a successional series in Dinghushan Mountain of Southern China. The results showed that after incubation for 52 weeks, the cumulative emission of CO2-C from PMF, PBMF and MEBF soil was 30.66 +/- 3.36, 58.17 +/- 7.25 and 59.31 +/- 13.58 mg x kg(-1), respectively, and 64.12%, 64.41% and 65.12% of which were released in the first 9 weeks. The cumulative emission of CO2-C was always significantly smaller from PMF soil than from PBMF and MEBF soils, and its change pattern over time fitted well with a two-pool kinetic model. The parameters based on the model implicated that the mineralization rates of soil labile and recalcitrant organic carbon tended to decrease with the forest type changing from PMF to PBMF and MEBF. The cumulative amount of CH4 after 52 weeks incubation and the net production of available N and nitrate after 20 weeks incubation were significantly higher in MEBF soil than in PBMF soil, and also, in PBMF soil than in PMF soil. NO3(-) -N was the dominant form in net available N production. The change in soil organic carbon mineralization rate caused by forest type change was an inherent way to affect soil organic carbon content.

  12. The influence of organic amendments on soil aggregate stability from semiarid sites

    NASA Astrophysics Data System (ADS)

    Hueso Gonzalez, Paloma; Francisco Martinez Murillo, Juan; Damian Ruiz Sinoga, Jose

    2016-04-01

    Restoring the native vegetation is the most effective way to regenerate soil health. Under these conditions, vegetation cover in areas having degraded soils may be better sustained if the soil is amended with an external source of organic matter. The addition of organic materials to soils also increases infiltration rates and reduces erosion rates; these factors contribute to an available water increment and a successful and sustainable land management. The goal of this study was to analyze the effect of various organic amendments on the aggregate stability of soils in afforested plots. An experimental paired-plot layout was established in southern of Spain (homogeneous slope gradient: 7.5%; aspect: N170). Five amendments were applied in an experimental set of plots: straw mulching; mulch with chipped branches of Aleppo Pine (Pinus halepensis L.); TerraCotten hydroabsobent polymers; sewage sludge; sheep manure and control. Plots were afforested following the same spatial pattern, and amendments were mixed with the soil at the rate 10 Mg ha-1. The vegetation was planted in a grid pattern with 0.5 m between plants in each plot. During the afforestation process the soil was tilled to 25 cm depth from the surface. Soil from the afforested plots was sampled in: i) 6 months post-afforestation; ii) 12 months post-afforestation; iii) 18 months post-afforestation; and iv) 24 months post-afforestation. The sampling strategy for each plot involved collection of 4 disturbed soil samples taken from the surface (0-10 cm depth). The stability of aggregates was measured by wet-sieving. Regarding to soil aggregate stability, the percentage of stable aggregates has increased slightly in all the treatments in relation to control. Specifically, the differences were recorded in the fraction of macroaggregates (≥ 0.250 mm). The largest increases have been associated with straw mulch, pinus mulch and sludge. Similar results have been registered for the soil organic carbon content

  13. 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.

  14. Priming effects and enzymatic activity in Israeli soils under treated wastewater and freshwater irrigation

    NASA Astrophysics Data System (ADS)

    Anissimova, Marina; Heinze, Stefanie; Chen, Yona; Tarchitzky, Jorge; Marschner, Bernd

    2014-05-01

    Irrigation of soils with treated wastewater (TWW) directly influences microbial processes of soil. TWW contains easily decomposable organic material, which can stimulate the activity of soil microorganisms and, as a result, lead to the excessive consumption of soil organic carbon pool. We investigated the effects of irrigation with TWW relative to those of irrigation with freshwater (FW) on the microbial parameters in soils with low (7%) and medium (13%) clay content in a lysimeter experiment. The objectives of our study were to (i) determine the impact of water quality on soil respiration and enzymatic activity influenced by clay content and depth, and (ii) work out the changes in the turnover of soil organic matter (PE, priming effects). Samples were taken from three soil depths (0-10, 10-20, and 40-60 cm). Soil respiration and PE were determined in a 21-days incubation experiment after addition of uniformly 14C-labeled fructose. Activity of 10 extracellular enzymes (EEA, from C-, N-, P-, and S-cycle), phenol oxidase and peroxidase activity (PO+PE), and dehydrogenase activity (DHA) were assayed. Microbial Community-Level Physiological Profiles (CLPP) using four substrates, and microbial biomass were determined. The results showed that the clay content acted as the main determinative factor. In the soil with low clay content the water quality had a greater impact: the highest PE (56%) was observed in the upper layer (0-10cm) under FW irrigation; EEA of C-, P-, and S-cycles was significantly higher in the upper soil layer under TWW irrigation. Microbial biomass was higher in the soil under TWW irrigation and decreased with increasing of depth (50 μg/g soil in the upper layer, 15 μg/g soil in the lowest layer). This tendency was also observed for DHA. Contrary to the low clay content, in the soil with medium clay content both irrigation types caused the highest PE in the lowest layer (65% under FW irrigation, 48% under TWW irrigation); the higher substrate

  15. Effects of Straw Return in Deep Soils with Urea Addition on the Soil Organic Carbon Fractions in a Semi-Arid Temperate Cornfield.

    PubMed

    Zou, Hongtao; Ye, Xuhong; Li, Jiaqi; Lu, Jia; Fan, Qingfeng; Yu, Na; Zhang, Yuling; Dang, Xiuli; Zhang, Yulong

    2016-01-01

    Returning straw to deep soil layers by using a deep-ditching-ridge-ploughing method is an innovative management practice that improves soil quality by increasing the soil organic carbon (SOC) content. However, the optimum quantity of straw return has not been determined. To solve this practical production problem, the following treatments with different amounts of corn straw were investigated: no straw return, CK; 400 kg ha-1 straw, S400; 800 kg ha-1 straw, S800; 1200 kg ha-1 straw, S1200; and 1600 kg ha-1 straw, S1600. After straw was returned to the soil for two years, the microbial biomass C (MBC), easily oxidized organic C (EOC), dissolved organic C (DOC) and light fraction organic C (LFOC) content were measured at three soil depths (0-10, 10-20, and 20-40 cm). The results showed that the combined application of 800 kg ha-1 straw significantly increased the EOC, MBC, and LFOC contents and was a suitable agricultural practice for this region. Moreover, our results demonstrated that returning straw to deep soil layers was effective for increasing the SOC content.

  16. 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.

  17. Potential for Carbon Sequestration using Organic Amendments on Rangeland Soils

    NASA Astrophysics Data System (ADS)

    Ryals, R.; Silver, W. L.

    2009-12-01

    Managed rangelands represent a geographically large land-use footprint and thus have considerable potential to sequester carbon (C) in soil through changes in management practices. Organic amendments are frequently added to agricultural and rangeland soils in an effort to improve fertility and yield, yet little is known about their impact on greenhouse gas dynamics and soil biogeochemical dynamics, especially in rangeland soils. This research aims to explore the effects of organic amendments on soil chemical and physical properties, plant inputs, and soil C and N dynamics in managed rangeland ecosystems. Our research uses field manipulations at two Mediterranean grassland ecosystems replicated within and across bioclimatic zones: the Sierra Foothills Research and Extension Center (SFREC) in Browns Valley, CA and the Nicasio Native Grass Ranch in Nicasio, CA. Both sites are dominated by annual grasses and are moderately grazed by cattle. Three replicate blocks at each site contain 60m x 25m treatment plots (organic amendments and control) with 5m buffer strips. Organic amendments were applied at a level of 14 MgC/ha (equivalent to a 1.27cm surface dressing) at the beginning of the wet season (December 2008). During the wet season (October through June), carbon dioxide (CO2) flux was measured weekly using a LI-8100, while fluxes of methane (CH4) and nitrous oxide (N2O) were measured biweekly using static flux chambers. During the dry season (June through September), fluxes were measured biweekly and monthly, respectively. Soil organic C (SOC) and nitrogen (N) were measured prior to treatment and seven months following treatment at 0-10, 10-30, 30-50, and 50-100 cm depths. Soil moisture and temperature were measured continuously. Changes in oxidative and hydrolytic extracellular enzyme activities are also being explored. After the first year of management, both sites responded similarly to treatments in both trend and magnitude. For example, at SFREC, total soil

  18. Ozone concentration and pulmonary response relationships for 6. 6-hour exposures with five hours of moderate exercise to 0. 08, 0. 10, and 0. 12 ppm

    SciTech Connect

    Horstman, D.H.; Folinsbee, L.J.; Ives, P.J.; Abdul-Salaam, S.; McDonnell, W.F. )

    1990-11-01

    The magnitudes of pulmonary responses we previously observed (1) following 6.6-h exposures to 0.12 ppm ozone (O3) suggested that responses would also occur with similar exposures at lower O3 concentrations. The objective of this study was to determine the extent of pulmonary function decrements, respiratory discomfort, and increased airway reactivity to methacholine induced by exposure to O3 below 0.12 ppm. Separate 6.6-h chamber exposures to 0.00, 0.08, 0.10, and 0.12 ppm O3 included six 50-min periods of moderate exercise (VE approximately equal to 39 L/min, HR approximately equal to 115 bpm, and VO2 approximately equal to 1.5 L/min). Each exercise period was followed by 10 min of rest. A 35-min lunch break was included midway through the exposure. Although not intended as an exact simulation, the overall duration, intensity, and metabolic requirements of the exercise performed were representative of a day of moderate to heavy work or play. Preexposure FEV1 averaged 4.39 L, and essentially no change (+0.03 L) occurred with exposure to 0.00 ppm O3. Significant decreases (p less than 0.01) of -0.31, -0.30, and -0.54 L were observed with exposures to 0.08, 0.10, and 0.12 ppm, respectively. The provocative dose of methacholine required to increase airway resistance by 100% (PD100) was 58 cumulative inhalation units (CIU) following exposure to 0.00 ppm and was significantly reduced (p less than 0.01) to 37 CIU at 0.08, 31 CIU at 0.10, and 26 CIU at 0.12 ppm O3; reductions in PD100 are considered indicative of increases in nonspecific airway responsiveness.

  19. Effects of poultry manure, compost, and biochar amendments on soil nitrogen dynamics in maize production systems

    NASA Astrophysics Data System (ADS)

    Ryals, R.; Tang, J.; Hastings, M. G.; Dell, C. J.; Sims, T.

    2013-12-01

    Intensification of animal agriculture has profound impacts on the global and local biogeochemistry of nitrogen (N), resulting in consequences to environmental and human health. In the Chesapeake Bay watershed, intensive agriculture is the primary contributor to N pollution, with animal manure comprising more than half of N from agriculture. Management interventions may play an important role in mitigating reactive N pollution in the Bay watershed. The objective of our research was to test management strategies that maximize benefits of poultry manure as an agricultural resource while minimizing it as a source of reactive nitrogen to the atmosphere and ground and surface waters. We conducted field experiments in two agricultural regions of the Chesapeake Bay watershed (Georgetown, Delaware and State College, Pennsylvania) to explore the effects of poultry manure amendments on gaseous N losses and soil N transformations. Treatments were applied at rates needed to meet the plant N demand at each site and included unfertilized controls, fertilizer N (urea), and raw, composted, or and biocharred poultry manure. The fate of the N from all sources was followed throughout the growing season. Global greenhouse gases emitted from soil (nitrous oxide [N2O] and carbon dioxide [CO2]) and regional air pollutants (nitrogen oxides [NOx] and ammonia [NH3]) were measured. Gas measurements were coupled with data on treatment effects on temperature, moisture, and concentrations of nitrate (NO3¬-) and ammonium (NH4+) in surface soils (0-10 cm). Soil NO3- and NH4+ were also measured approximately monthly in the soil profile (0-10, 10-30, 30-50, 50-70, and 70-100 cm) as an index of leaching potential. Plant N uptake and grain production were also quantified to quantify crop N use efficiency and compare measured N losses for each N source. Our results suggest that the form of poultry manure amendments can affect the magnitude of reactive N losses to the environment.

  20. Aggregate and soil organic carbon dynamics in South Chilean Andisols

    NASA Astrophysics Data System (ADS)

    Huygens, D.; Boeckx, P.; Van Cleemput, O.; Oyarzún, C.; Godoy, R.

    2005-06-01

    Extreme sensitivity of soil organic carbon (SOC) to climate and land use change warrants further research in different terrestrial ecosystems. The aim of this study was to investigate the link between aggregate and SOC dynamics in a chronosequence of three different land uses of a south Chilean Andisol: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata plantation (PINUS). Total carbon content of the 0-10cm soil layer was higher for GRASS (6.7 kg C m-2) than for PINUS (4.3 kg C m-2, while TC content of SGFOR (5.8 kg C m-2) was not significantly different from either one. High extractable oxalate and pyrophosphate Al concentrations (varying from 20.3-24.4 g kg-1, and 3.9-11.1 g kg-1, respectively) were found in all sites. In this study, SOC and aggregate dynamics were studied using size and density fractionation experiments of the SOC, δ13C and total carbon analysis of the different SOC fractions, and C mineralization experiments. The results showed that electrostatic sorption between and among amorphous Al components and clay minerals is mainly responsible for the formation of metal-humus-clay complexes and the stabilization of soil aggregates. The process of ligand exchange between SOC and Al would be of minor importance resulting in the absence of aggregate hierarchy in this soil type. Whole soil C mineralization rate constants were highest for SGFOR and PINUS, followed by GRASS (respectively 0.495, 0.266 and 0.196 g CO2-Cm-2d-1 for the top soil layer). In contrast, incubation experiments of isolated macro organic matter fractions gave opposite results, showing that the recalcitrance of the SOC decreased in another order: PINUS>SGFOR>GRASS. We deduced that electrostatic sorption processes and physical protection of SOC in soil aggregates were the main processes determining SOC stabilization. As a result, high aggregate carbon concentrations, varying from 148 till 48 g kg-1, were encountered for all land use sites. Al

  1. Paddy-field contamination with 134Cs and 137Cs due to Fukushima Dai-ichi Nuclear Power Plant accident and soil-to-rice transfer coefficients.

    PubMed

    Endo, Satoru; Kajimoto, Tsuyoshi; Shizuma, Kiyoshi

    2013-02-01

    The transfer coefficient (TF) from soil to rice plants of (134)Cs and (137)Cs in the form of radioactive deposition from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011 was investigated in three rice paddy fields in Minami-Soma City. Rice crops were planted in the following May and harvested at the end of September. Soil cores of 30-cm depth were sampled from rice-planted paddy fields to measure (134)Cs and (137)Cs radioactivity at 5-cm intervals. (134)Cs and (137)Cs radioactivity was also measured in rice ears (rice with chaff), straws and roots. The rice ears were subdivided into chaff, brown rice, polished rice and rice bran, and the (134)Cs and (137)Cs radioactivity concentration of each plant part was measured to calculate the respective TF from the soil. The TF of roots was highest at 0.48 ± 0.10 in the field where the (40)K concentration in the soil core was relatively low, in comparison with TF values of 0.31 and 0.38 in other fields. Similar trends could be found for the TF of whole rice plants, excluding roots. The TF of rice ears was relatively low at 0.019-0.026. The TF of chaff, rice bran, brown rice and polished rice was estimated to be 0.049, 0.10-0.16, 0.013-0.017 and 0.005-0.013, respectively.

  2. Micro and macroscopic investigation to quantify tillage impact on soil hydrodynamic behaviour

    NASA Astrophysics Data System (ADS)

    Beckers, E.; Roisin, C.; Plougonven, E.; Deraedt, D.; Léonard, A.; Degré, A.

    2012-04-01

    Nowadays, tillage simplification is an increasing practice. Many advantages are cited in the literature, such as energy saving, soil conservation etc. Agricultural management practices influence soil structure, but consequent changes in soil hydrodynamic behaviour at the field scale are still not well understood. Many studies focus only on macroscopic measurements which do not provide mechanistic explanations. Moreover, research shows divergent conclusions over structure modification. The aim of this work is to fill this gap by quantifying soil structure modification depending on tillage intensity through both macroscopic and microscopic measurements, the latter improving our comprehension of the fundamental mechanisms involved. Our experiment takes place in Gentinnes (Walloon Brabant, Belgium), on a field organized in a Latin square scheme. Since 2004, plots have been cultivated in conventional tillage (CT) or in reduced tillage (RT). The latter consists in sowing after stubble ploughing of about 10cm. The crop rotation is sugar beet followed by winter wheat. The soil is mainly composed of silt loam and can be classified as a Luvisol. Macroscopic investigations consist in establishing pF and K(h) curves and 3D soil strength profiles. At the microscale, 3D morphologic parameters are measured using X-ray microtomography. Because of the variation of working depth between management practices (10cm for RT vs. 25cm for CT), two horizons were investigated: H1 between 0-10cm and H2 between 12-25cm. 3D soil strength profiles were established thanks to a fully automated penetrometer (30° angle cone with a base area of 10mm2) which covered a 160 × 80cm2 area with 5cm spacing between neighbouring points. At each node, penetration was performed and soil strength measurements were collected every 1cm from 5 to 55cm depth. K(h) curves were provided by 20cm diameter tension-infiltrometer measurements (Eijkelkamp Agrisearch Equipment). Undisturbed soil samples were removed from

  3. Comparison of wheat and safflower cultivation areas in terms of total carbon and some soil properties under semi-arid climate conditions

    NASA Astrophysics Data System (ADS)

    Turgut, B.

    2015-03-01

    The aim of this study was to compare the soils of the wheat cultivation area (WCA) and the safflower cultivation area (SCA) within semi-arid climate zones in terms of their total carbon, nitrogen, sulphur contents, particle size distribution, aggregate stability, organic matter content, and pH values. This study presents the results from the analyses of 140 soil samples taken at two soil layers (0-10 and 10-20 cm) in the cultivation areas. At the end of the study, it has been established that there were significant differences between the cultivation areas in terms of soil physical properties such as total carbon (TC), total nitrogen (TN), total sulphur (TS) contents and pH, while only the TN content resulted in significantly different between the two soil layers. Moreover significant differences were identified in the cultivation areas in terms of soil physical properties including clay and sand contents, aggregate stability and organic matter content, whereas the only significant difference found among the soil layers was that of their silt content. Since safflower contains higher amounts of biomass than wheat, we found higher amounts of organic matter content and, therefore, higher amounts of TN and TS content in the soils of the SCA. In addition, due to the fact that wheat contains more cellulose - which takes longer to decompose - the TC content of the soil in the WCA were found to be higher than that of the SCA. The results also revealed that the WCA had a higher carbon storage capacity.

  4. Comparison of wheat and safflower cultivation areas in terms of total carbon and some soil properties under semi-arid climate conditions

    NASA Astrophysics Data System (ADS)

    Turgut, B.

    2015-06-01

    The aim of this study was to compare the soils of the wheat cultivation area (WCA) and the safflower cultivation area (SCA) within semi-arid climate zones in terms of their total carbon, nitrogen, and sulphur contents, particle size distribution, aggregate stability, organic matter content, and pH values. This study presents the results from the analyses of 140 soil samples taken at two soil layers (0-10 and 10-20 cm) in the cultivation areas. At the end of the study, it was established that there were significant differences between the cultivation areas in terms of soil physical properties such as total carbon (TC), total nitrogen (TN), total sulphur (TS) contents and pH, while only the TN content was significantly different between the two soil layers. Moreover, significant differences were identified between the cultivation areas in terms of soil physical properties including clay and sand contents, aggregate stability, and organic matter content, whereas the only significant difference found among the soil layers was that of their silt content. Since safflower contains higher amounts of biomass than wheat, we found higher amounts of organic matter content and, therefore, higher amounts of TN and TS content in the soils of the SCA. In addition, due to the fact that wheat contains more cellulose - which takes longer to decompose - the TC content of the soil in the WCA was found to be higher than that in the SCA. The results also revealed that the WCA had a higher carbon storage capacity.

  5. Soil microbial responses to nitrogen addition in arid ecosystems.

    PubMed

    Sinsabaugh, Robert L; Belnap, Jayne; Rudgers, Jennifer; Kuske, Cheryl R; Martinez, Noelle; Sandquist, Darren

    2015-01-01

    The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH, and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts). We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg N ha(-1) y(-1) from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm) and bulk soils (0-10 cm) were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities and rates of N transformation. By most measures, nutrient availability, microbial biomass, and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N amendment that included data from 14 other studies. Effect sizes were calculated for biomass and metabolic responses. Regressions of effect sizes, calculated for biomass, and metabolic responses, showed similar trends in relation to N application rate and N load (rate × duration). The critical points separating positive from negative treatment effects were 88 kg ha(-1) y(-1) and 159 kg ha(-1), respectively, for biomass, and 70 kg ha(-1) y(-1) and 114 kg ha(-1), respectively, for metabolism. These critical values are comparable to those for microbial biomass, decomposition rates and respiration reported in broader meta-analyses of N amendment effects in mesic ecosystems. However, large effect sizes at low N

  6. Microbial physiology and soil CO2 efflux after 9 years of soil warming in a temperate forest - no indications for thermal adaptations.

    PubMed

    Schindlbacher, Andreas; Schnecker, Jörg; Takriti, Mounir; Borken, Werner; Wanek, Wolfgang

    2015-11-01

    Thermal adaptations of soil microorganisms could mitigate or facilitate global warming effects on soil organic matter (SOM) decomposition and soil CO2 efflux. We incubated soil from warmed and control subplots of a forest soil warming experiment to assess whether 9 years of soil warming affected the rates and the temperature sensitivity of the soil CO2 efflux, extracellular enzyme activities, microbial efficiency, and gross N mineralization. Mineral soil (0-10 cm depth) was incubated at temperatures ranging from 3 to 23 °C. No adaptations to long-term warming were observed regarding the heterotrophic soil CO2 efflux (R10 warmed: 2.31 ± 0.15 μmol m(-2)  s(-1) , control: 2.34 ± 0.29 μmol m(-2)  s(-1) ; Q10 warmed: 2.45 ± 0.06, control: 2.45 ± 0.04). Potential enzyme activities increased with incubation temperature, but the temperature sensitivity of the enzymes did not differ between the warmed and the control soils. The ratio of C : N acquiring enzyme activities was significantly higher in the warmed soil. Microbial biomass-specific respiration rates increased with incubation temperature, but the rates and the temperature sensitivity (Q10 warmed: 2.54 ± 0.23, control 2.75 ± 0.17) did not differ between warmed and control soils. Microbial substrate use efficiency (SUE) declined with increasing incubation temperature in both, warmed and control, soils. SUE and its temperature sensitivity (Q10 warmed: 0.84 ± 0.03, control: 0.88 ± 0.01) did not differ between warmed and control soils either. Gross N mineralization was invariant to incubation temperature and was not affected by long-term soil warming. Our results indicate that thermal adaptations of the microbial decomposer community are unlikely to occur in C-rich calcareous temperate forest soils.

  7. Responses of soil nutrient concentrations and stoichiometry to different human land uses in a subtropical tidal wetland

    PubMed Central

    Wang, W.; Sardans, J.; Zeng, C.; Zhong, C.; Li, Y.; Peñuelas, J.

    2015-01-01

    We studied the impacts of anthropogenic changes in land use on the stoichiometric imbalance of soil carbon (C), nitrogen (N), phosphorus (P) and potassium (K) in Phragmites australis wetlands in the Minjiang River estuary. We compared five areas with different land uses: P. australis wetland (control), grassland, a mudskipper breeding flat, pond aquaculture and rice cropland. Human activity has affected the elemental and stoichiometric compositions of soils through changes in land use. In general, soil C and N concentrations were lower and total soil K concentrations were higher at the sites under human land uses relative to the control site, and total soil P concentrations were generally not significantly different. The close relationship between total soil C and N concentrations in all cases, including fertilization with N, suggested that N was the most limiting nutrient in these wetlands. Lower soil N concentrations and similar soil P concentrations and higher soil K concentrations under human land-use activities suggest that human activity has increased the role of N limitation in these wetlands. Only grassland use increases soil N contents (only in the 0-10 cm of soil). Despite N fertilization, lower soil N concentrations were also observed in the rice cropland, indicating the difficulty of avoiding N limitation in these wetlands. The observed lower soil N:P ratio, together with higher soil P and K availabilities in rice croplands, is consistent with the tendency of human activity to change the competitive relationships of plants, in this case favoring species adapted to high rates of growth (low N:P ratio) and/or favoring plants with high demands for P and K. Both, soil C storage and respiration were higher in grasslands, likely due to the introduction of grasses, which led to a high density of plants, increased grazing activity and soil compaction. Soil C storage and respiration were lower under human land uses, except in the rice cropland, with respect to

  8. Development of indices to predict phosphorus release from wetland soils.

    PubMed

    Mukherjee, A; Nair, V D; Clark, M W; Reddy, K R

    2009-01-01

    The U.S. Environmental Protection Agency created the Clean Water Action Plan to develop nutrient criteria for four water body types: lakes and reservoirs, rivers and streams, estuaries, and wetlands. Significant progress has been made in open water systems. However, only areas in and around the Florida Everglades have had numeric nutrient criteria set, due to the complexity, heterogeneity, and limited information available for wetlands. Our objective was to evaluate various soil tests to predict significant P release potential of soil in wetlands. A total of 630 surface soil samples (0-10 cm) were collected for this study from four southeastern states: Florida, Alabama, Georgia, and South Carolina. Soil samples were collected from the center of wetlands, the edge of the wetlands, and from adjacent uplands. The phosphorus saturation ratios (PSR), calculated using P, Fe, and Al molar concentrations from Mehlich 1 (M1-PSR), Mehlich 3 (M3-PSR), and oxalate (Ox-PSR) extractions and the amount of P extracted by different extractants were used to predict P loss potential from a soil. Total phosphorus (TP) concentration in wetland soils, estimated as the 75th percentile of the distribution of least impacted wetland soils as an example, was approximately 550 mg kg(-1). Based on this reference background condition, procedures for obtaining threshold values for P release to the surrounding water bodies were developed and threshold values calculated: M1-P = 24 mg kg(-1), M3-P = 44 mg kg(-1), Ox-PSR = 0.079, M1-PSR = 0.101, and M3-PSR = 0.067.

  9. Effect of different crops on soil organic matter and biological activity in Oxisols under three different crops

    NASA Astrophysics Data System (ADS)

    Toledo, Diana Marcela; Arzuaga, Silvia; Dalurzo, Humberto; Zornoza, Raúl; Vazquez, Sara

    2015-04-01

    The objective of this work was to evaluate changes in soil organic matter in Oxisols under different crops compared to native rainforest, and to assess if acid phosphatase activity (APA) could be a good indicator for SOC changes and soil quality. The experimental design consisted of four completely randomized blocks with four treatments: subtropical rainforest (F); yerba mate crop (I) (Ilex paraguariensis SH.); citrus crop (C) (Citrus unshiu Marc); and tobacco crop (T) (Nicotiana tabacum L.). Soil samples were taken at 0-10; 10-20 and 20-30 cm depths. The variables measured were soil organic carbon (SOC), APA, clay content, pH, total nitrogen (Nt), available phosphorus (P) and CO2 emissions. All data were analyzed by ANOVA to assess the effects of land-use changes. The treatment means were compared through Duncan's multiple range tests (p<0.05). The relationship between variables was determined with a simple correlation analysis and with a multiple linear regression analysis through the stepwise method. These soils showed an acid reaction and their clay content was over 650 g kg-1 for the three depths. SOC and N contents were higher in native soils, intermediate for the citrus crop, and lower under both tobacco and yerba mate crops. CO2 emissions were higher in the rainforest (47.32 kg ha-1 of CO2) than in cultivated soils, which indicates that biological activity is enhanced in rainforest soils where substrates for soil biota and fauna are more readily available. The variability of 76% in APA was explained by total nitrogen, which is closely related to soil organic matter, and by available P. Conversion of subtropical rainforests into agricultural lands reduced SOC content and acid phosphatase activity, thereby lowering soil quality. In this study, acid phosphatase activity proved to be a sensitive indicator to detect changes from pristine to cropped soils, but it failed to distinguish differences among crop systems.

  10. Altered precipitation regime affects the function and composition of soil microbial communities on multiple time scales.

    PubMed

    Zeglin, L H; Bottomley, P J; Jumpponen, A; Rice, C W; Arango, M; Lindsley, A; McGowan, A; Mfombep, P; Myrold, D D

    2013-10-01

    Climate change models predict that future precipitation patterns will entail lower-frequency but larger rainfall events, increasing the duration of dry soil conditions. Resulting shifts in microbial C cycling activity could affect soil C storage. Further, microbial response to rainfall events may be constrained by the physiological or nutrient limitation stress of extended drought periods; thus seasonal or multiannual precipitation regimes may influence microbial activity following soil wet-up. We quantified rainfall-driven dynamics of microbial processes that affect soil C loss and retention, and microbial community composition, in soils from a long-term (14-year) field experiment contrasting "Ambient" and "Altered" (extended intervals between rainfalls) precipitation regimes. We collected soil before, the day following, and five days following 2.5-cm rainfall events during both moist and dry periods (June and September 2011; soil water potential = -0.01 and -0.83 MPa, respectively), and measured microbial respiration, microbial biomass, organic matter decomposition potential (extracellular enzyme activities), and microbial community composition (phospholipid fatty acids). The equivalent rainfall events caused equivalent microbial respiration responses in both treatments. In contrast, microbial biomass was higher and increased after rainfall in the Altered treatment soils only, thus microbial C use efficiency (CUE) was higher in Altered than Ambient treatments (0.70 +/- 0.03 > 0.46 +/- 0.10). CUE was also higher in dry (September) soils. C-acquiring enzyme activities (beta-glucosidase, cellobiohydrolase, and phenol oxidase) increased after rainfall in moist (June), but not dry (September) soils. Both microbial biomass C:N ratios and fungal:bacterial ratios were higher at lower soil water contents, suggesting a functional and/or population-level shift in the microbiota at low soil water contents, and microbial community composition also differed following wet

  11. VLA Images of Venus at 1.3 CM and 2 CM Wavelengths

    NASA Astrophysics Data System (ADS)

    Suleiman, S. H.; Kolodner, M. A.; Butler, B. J.; Steffes, P. G.

    1996-09-01

    On April 5, 1996, we performed an observation of Venus using the Very Large Array (VLA) at 15 GHz (2 cm) and 22 GHz (1.3 cm) simultaneously. High resolution continuum images for Venus were obtained at both frequencies. These images show significant polar darkening at latitudes above 60(deg) which is consistent with the results obtained by the Pioneer Venus Orbiter Infrared Radiometer (OIR) experiment (Taylor et al., J. Geophys. Res. 85, 7963-8006, 1980). These images are currently being used to detect potential spatial (longitudinal and latitudinal) variations in the abundances of gaseous sulfur dioxide (SO_2) and gaseous sulfuric acid (H_2SO_4) across the disk of Venus. Our new radiative transfer model (RTM) has shown that the emission spectrum is especially sensitive to the abundances of these constituents at these wavelengths. The detection of these constituents is being accomplished by matching the computed emission from our RTM to the measured emission of Venus by the VLA. Our RTM incorporates the newly developed Ben Reuven formalism which provides a more accurate characterization of the microwave absorption of gaseous SO_2 (Suleiman et al., J. Geophys. Res. 101, 4623-4635, 1996). A description of the observation, visibility data, and images are presented. This work was supported by the NASA Planetary Atmospheres Program under grant NAGW-533.

  12. Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 2. Paddy soil.

    PubMed

    Dittmar, Jessica; Voegelin, Andreas; Roberts, Linda C; Hug, Stephan J; Saha, Ganesh C; Ali, M Ashraf; Badruzzaman, A Borhan M; Kretzschmar, Ruben

    2007-09-01

    Arsenic-rich groundwater from shallow tube wells is widely used for the irrigation of boro rice in Bangladesh and West Bengal. In the long term this may lead to the accumulation of As in paddy soils and potentially have adverse effects on rice yield and quality. In the companion article in this issue, we have shown that As input into paddy fields with irrigation water is laterally heterogeneous. To assess the potential for As accumulation in soil, we investigated the lateral and vertical distribution of As in rice field soils near Sreenagar (Munshiganj, Bangladesh) and its changes over a 1 year cycle of irrigation and monsoon flooding. At the study site, 18 paddy fields are irrigated with water from a shallow tube well containing 397 +/- 7 microg L(-1) As. The analysis of soil samples collected before irrigation in December 2004 showed that soil As concentrations in paddy fields did not depend on the length of the irrigation channel between well and field inlet. Within individual fields, however, soil As contents decreased with increasing distance to the water inlet, leading to highly variable topsoil As contents (11-35 mg kg(-1), 0-10 cm). Soil As contents after irrigation (May 2005) showed that most As input occurred close to the water inlet and that most As was retained in the top few centimeters of soil. After monsoon flooding (December 2005), topsoil As contents were again close to levels measured before irrigation. Thus, As input during irrigation was at least partly counteracted by As mobilization during monsoon flooding. However, the persisting lateral As distribution suggests net arsenic accumulation over the past 15 years. More pronounced As accumulation may occur in regions with several rice crops per year, less intense monsoon flooding, or different irrigation schemes. The high lateral and vertical heterogeneity of soil As contents must be taken into account in future studies related to As accumulation in paddy soils and potential As transfer into rice.

  13. Polycyclic aromatic hydrocarbons, black carbon, and molecular markers in soils of Switzerland.

    PubMed

    Bucheli, Thomas D; Blum, Franziska; Desaules, André; Gustafsson, Orjan

    2004-09-01

    Polycyclic aromatic hydrocarbons (PAH) were analysed in 23 soil samples (0-10 cm layer) from the Swiss soil monitoring network (NABO) together with total organic carbon (TOC) and black carbon (BC) concentration, as well as some PAH source diagnostic ratios and molecular markers. The concentrations of the sum of 16 EPA priority PAHs ranged from 50 to 619 microg/kg dw. Concentrations increased from arable, permanent and pasture grassland, forest, to urban soils and were 21-89% lower than median numbers reported in the literature for similar Swiss and European soils. NABO soils contained BC in concentrations from 0.4 to 1.8 mg/g dw, except for two sites with markedly higher levels. These numbers corresponded to 1-6% of TOC and were comparable to the limited published BC data in soil and sediments obtained with comparable analytical methods. The various PAH ratios and molecular markers pointed to a domination of pyrogenically formed PAHs in Swiss soils. In concert, the gathered data suggest the following major findings: (1) gas phase PAHs (naphthalene to fluorene) were long-range transported, cold-condensated at higher altitudes, and approaching equilibrium with soil organic matter (OM); (2) (partially) particle-bound PAHs (phenanthrene to benzo[ghi]perylene) were mostly deposited regionally in urban areas, and not equilibrated with soil OM; (3) Diesel combustion appeared to be a major emission source of PAH and BC in urban areas; and (4) wood combustion might have contributed significantly to PAH burdens in some soils of remote/alpine (forest) sites.

  14. Fate of atrazine in a soil under different agronomic management practices.

    PubMed

    Prado, B; Fuentes, M; Verhulst, N; Govaerts, B; De León, F; Zamora, O

    2014-01-01

    Agricultural management affects the movement of atrazine in soil and leaching to groundwater. The objective of this study was to determine atrazine adsorption in a soil after 20 years of atrazine application under agronomic management practices differing in tillage practice (conventional and zero tillage), residue management (with and without residue retention) and crop rotation (wheat-maize rotation and maize monoculture). Atrazine sorption was determined using batch and column experiments. In the batch experiment, the highest distribution coefficient Kd (1.1 L kg(-1)) at 0-10 cm soil depth was observed under zero tillage, crop rotation and residue retention (conservation agriculture). The key factor in adsorption was soil organic matter content and type. This was confirmed in the column experiment, in which the highest Kd values were observed in treatments with residue retention, under either zero or conventional tillage (0.81 and 0.68 L kg(-1), respectively). Under zero tillage, the fact that there was no soil movement helped to increase the Kd. The increased soil organic matter content with conservation agriculture may be more important than preferential flow due to higher pore connectivity in the same system. The soil's capacity to adsorb 2-hydroxyatrazine (HA), an important atrazine metabolite, was more important than its capacity to adsorb atrazine, and was similar under all four management practices (Kd ranged from 30 to 40 L kg(-1)). The HA adsorption was attributed to the type and amount of clay in the soil, which is unaffected by agronomic management. Soils under conservation agriculture had higher atrazine retention potential than soils under conventional tillage, the system that predominates in the study area.

  15. [Topsoil phosphorus forms and availability of different soil and water conservation plantations in typical black soil region, northeast China].

    PubMed

    Yang, Xiao-Yan; Fan, Rui-Ying; Wang, En-Heng; Xia, Xiang-You; Chen, Xiang-Wei

    2014-06-01

    Aiming to understand soil phosphorus status of plantations in typical black soil region of Northeast China, the topsoil (0-10 cm) phosphorus fractionations and its availability were examined in four soil and water conservation plantations dominantly composed of Larix gmelini, Fraxinus mandshurica, Pinus sylvestris var. mongolica and Populus nigra var. italica x P. cathayan, respectively. The results showed that total P, Olsen-P and the concentration of different P fractionations in F. mandshurica and P. nigra var. italica x P. cathayan plantations were significantly higher than that of the other two coniferous plantations. Organic P was the major fractionation in the four plantations' topsoil, and sodium hydroxide extractable organic P (NaOH-Po ) representing moderately labile organic phosphorus was predominant, which accounted for 58.9% of total P. The contents of H2O-Pi and NaHCO3-P which were more labile to plant were lower, only accounting for 1.2% and 6.6% of total P, respectively. Except for NaHCO3-Po, all the other P fractions of four plantations correlated with each other, and they also had significant correlations with soil organic matter, total P, Olsen-P. Compared with the coniferous plantations, the broadleaf plantations presented higher availability of phosphorus.

  16. Distribution of phthalate esters in agricultural soil with plastic film mulching in Shandong Peninsula, East China.

    PubMed

    Li, Kankan; Ma, Dong; Wu, Juan; Chai, Chao; Shi, Yanxi

    2016-12-01

    The content of phthalate esters (PAEs) was investigated in 36 vegetable fields with plastic film mulching in Shandong Peninsula, East China. Soils at depths of 0-10 cm, 10-20 cm, and 20-40 cm were collected, and 16 PAEs were analyzed by gas chromatography-mass spectrometry. PAEs were detected in all the analyzed samples. The total contents of the 16 PAEs (Σ16PAEs) ranged from 1.374 to 18.810 mg/kg, with an average of 6.470 mg/kg. Among the four areas of Shandong Peninsula, including Qingdao, Weihai, Weifang, and Yantai, the highest Σ16PAE in the soil was observed in Weifang district (9.786 mg/kg), which is famous for large-scale vegetable production. Despite the significant differences among the Σ16PAEs, the PAE compositions in soils with plastic film mulching in Shandong Peninsula were comparable. Diethyl phthalate (DEP), diisobutyl phthalate, and di(4-methyl-2-pentyl) phthalate were present in all the samples, whereas di-n-hexyl phthalate was detected only in Qingdao (∼1%) and dicyclohexyl phthalate was observed only in Weifang (5.7-8.2%) in low proportions. The ratios of dimethyl phthalate, DEP, and di-n-butyl phthalate, which exceeded allowable concentrations, were 63.9-100% at different soil depths, indicating high PAE pollution. The concentration of butyl benzyl phthalate detected only in Weifang exceeded the recommended allowable soil concentration. Overall, the high PAE content in the soil with plastic film mulching in Shandong Peninsula is an issue of concern because of the large amounts of plastic film used.

  17. Assessment of heavy metal pollution in urban soils of Havana city, Cuba.

    PubMed

    Rizo, O Díaz; Castillo, F Echeverría; López, J O Arado; Merlo, M Hernández

    2011-10-01

    Concentrations of Co, Ni, Cu, Zn, Pb and Fe in the top-soils (0-10 cm) from urbanized and un-urbanized areas of Havana city were measured by X-ray fluorescence analysis. The mean Co, Ni, Cu, Zn and Pb contents in the urban topsoil samples (13.9 ± 4.1, 66 ± 26, 101 ± 51, 240 ± 132 and 101 ± 161 mg kg(-1), respectively) were compared with mean concentrations for other cities around the world. The results revealed the highest concentrations of metals in topsoil samples from industrial sites. Lowest metal contents were determined in the un-urbanized areas. The comparison with Dutch soil quality guidelines showed a slight contamination with Co, Ni Cu and Zn in all studied sites and with Pb in industrial soils. On the other hand, the metal-to-iron normalisation using Earth crust contents as background showed that soils from urbanized areas in Havana city (industrial sites, parks and school grounds) are moderately enriched with zinc, moderately to severe enriched (city parks and school grounds) and severe enriched (industrial sites) with lead. The values of integrated pollution index (IPI) indicated that industrial soils are middle and high contaminated by heavy metals (1.19 ≤ IPI ≤ 7.54), but enrichment index values (EI) shows that metal concentrations on the studied locations are not above the permissible levels for urban agriculture, except soils from power and metallurgical plants surroundings.

  18. Release of aged 14C-atrazine residues from soil facilitated by dry-wet cycles

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Yu, K.; Koeppchen, S.; Burauel, P.

    2012-04-01

    Intermittent dry-wet cycles may have an important effect on soil structure and aged pesticide residues release (1). A laboratory study was conducted to assess the maximum potential of water extractable aged atrazine residues influenced by soil drying and wetting. The used soil was obtained from an outdoor lysimeter (gleyic cambisol; Corg: 1.45%), containing environmentally aged (22 years) 14C-atrazine residues. For the experiment, soil from 0-10 cm depth was used since most residual 14C activity was previously found in this layer (2,3). Triplicate soil samples with a residual water content of approx. 8% were either dried (45° C) prior water addition or directly mixed with distilled water (soil+water: 1+2, w:w). The samples were shaken (150 rmp, 60 min, at 21° C), centrifuged (approx. 2000 g), and the supernatants were filtered. Water-extracted residual 14C activity was detected via liquid scintillation counter. The total water-extracted 14C activity (the amount of residual 14C activity in a sample equals 100%) was significantly higher (p

  19. The effect of compost on carbon cycling and the active soil microbiota

    SciTech Connect

    Singer, Esther; Woyke, Tanja; Ryals, Rebecca; Silver, Whendee

    2014-09-02

    Rangelands cover an estimated 40-70percent of global landmass, approximately one-third of the landmass of the United States and half of California. The soils of this vast land area has high carbon (C) storage capacity, which makes it an important target ecosystem for the mitigation of greenhouse gas emission and effects on climate change, in particular under land management techniques that favor increased C sequestration rates. While microbial communities are key players in the processes responsible for C storage and loss in soils, we have barely shed light on these highly complex processes in part due to the tremendous and seemingly intractable diversity of microbes, largely uncultured, that inhabit soil ecosystems. In our study, we compare Mediterranean grassland soil plots that were amended with greenwaste compost in a single event 6 years ago. Subsampling of control and amended plots was performed in depth increments of 0-10 cm. We present data on greenhouse gas emissions and budgets of carbon, nitrogen, phosphorus, and micronutrients in dependence of compost amendment. Changes in the active members of the soil microbial community were assessed using a novel approach combining flow cytometry and 16S tag sequencing disclosing who is active. This is the first study revealing the nature of actively metabolizing microbial community members linked to the geochemical characteristics of compost-amended soil.

  20. Leaching of oryzalin and diuron through undisturbed vineyard soil columns under outdoor conditions.

    PubMed

    Landry, David; Dousset, Sylvie; Andreux, Francis

    2006-03-01

    Field studies monitoring herbicide pollution in the vineyards of Burgundy (France) have revealed that drinking water reservoirs are contaminated with several pre-emergence herbicides. An assessment of the leaching of two such herbicides, diuron and oryzalin, was therefore performed using lysimeters, under outdoor conditions, from May 2001 to May 2002. Four vineyard soils from Vosne-Romanée (Burgundy) were chosen along a topolithosequence: a rendosol and three calcosols. After 673 mm of rainfall, greater amounts of diuron than oryzalin were measured in percolates: respectively 0.10-0.84% and 0.02-0.43% of applied herbicide, depending on soils. Measurements for diuron metabolites detected greater amounts of DCPMU than DCPU in the percolates: respectively 0.05-0.13% and 0-0.04% of the applied diuron. At the end of the monitoring period, more residues of diuron than oryzalin were recovered in the soil profiles: respectively 4.6-9% and 1.4-4.4%. The oryzalin residues were found mainly in the upper 10 cm of soil columns, whereas diuron residues were present in the whole core. The mobility of both oryzalin and diuron seems fairly well-related to soil organic carbon content; the mobility of diuron is also related to soil texture (sand and coarse material contents). Under such experimental conditions, this study confirms that diuron leaching, and therefore potential groundwater contamination, is greater than that of oryzalin.

  1. [Effects of soil thickness on spatiotemporal pattern of soil moisture in catchment level].

    PubMed

    Chen, Jia; Shi, Zhi-Hua; Li, Lu; Luo, Xuan

    2009-07-01

    Based on the fixed-spot observation, this paper analyzed the effects of soil thicknesses on the spatiotemporal pattern of soil moisture in the Wulongchi catchment of Danjiangkou, China. The soil moisture content increased soon after precipitation events, followed by a decline as the soil dried down, whilst its spatial heterogeneity exhibited an opposite pattern. The profile-averaged soil moisture content differed significantly with soil thickness. The soil with a thickness of 20 cm had lower profile-averaged moisture content whose variation trend was similar to that of precipitation and varied obviously among seasons; medium thickness (20-40 cm) soil had medium level of profile-averaged moisture content whose seasonal variation was moderately and affected by the characteristics of precipitation; while the soil with a thicknesses of > 40 cm had higher profile-averaged moisture content whose seasonal variation was relatively small. The profile distribution pattern of soil moisture was determined by the integrated effects of precipitation, evapotranspiration, and leakage, exhibiting increasing-type at semi-humid stage, waving-type at humid stage, and both of the two types at arid stage. There was a significant positive correlation between profile-averaged soil moisture content and soil thickness, and the correlation coefficient was 0.630-0.855. The moisture content in 0-15 cm soil layer had less correlation with soil thickness, but the moisture content in 20-55 cm soil layer was significantly correlated with soil thickness.

  2. Is tree species diversity or tree species identity the most important driver of European forest soil carbon stocks?

    NASA Astrophysics Data System (ADS)

    Vesterdal, Lars; Muhie Dawud, Seid; Raulund-Rasmussen, Karsten; Finér, Leena; Domisch, Timo

    2016-04-01

    Land management includes the selection of specific tree species and tree species mixtures for European forests. Studies of functional species diversity effects have reported positive effects for aboveground carbon (C) sequestration, but the question remains whether higher soil C stocks could also result from belowground niche differentiation including more efficient root exploitation of soils. We studied topsoil C stocks in tree species diversity gradients established within the FunDivEurope project to explore biodiversity-ecosystem functioning relationships in six European forest types in Finland, Poland, Germany, Romania, Spain and Italy. In the Polish forest type we extended the sampling to also include subsoils. We found consistent but modest effects of species diversity on total soil C stocks (forest floor and 0-20 cm) across the six European forest types. Carbon stocks in the forest floor alone and in the combined forest floor and mineral soil layers increased with increasing tree species diversity. In contrast, there was a strong effect of species identity (broadleaf vs. conifer) and its interaction with site-related factors. Within the Polish forest type we sampled soils down to 40 cm and found that species identity was again the main factor explaining total soil C stock. However, species diversity increased soil C stocks in deeper soil layers (20-40 cm), while species identity influenced C stocks significantly within forest floors and the 0-10 cm layer. Root biomass increased with diversity in 30-40 cm depth, and a positive relationship between C stocks and root biomass in the 30-40 cm layer suggested that belowground niche complementarity could be a driving mechanism for higher root carbon input and in turn a deeper distribution of C in diverse forests. We conclude that total C stocks are mainly driven by tree species identity. However, modest positive diversity effects were detected at the European scale, and stronger positive effects on subsoil C stocks

  3. Spatiotemporal variability of soil hydrological properties and its implication on small catchments hydrology

    NASA Astrophysics Data System (ADS)

    Ferreira, C. S. S.; Steenhuis, T. S.; Soares, D.; Ferreira, A. J. D.; Coelho, C. O. A.; Walsh, R. P. D.

    2012-04-01

    The increasing population pressure on the environment implies changes to land use and to landscape patterns within catchments, with impacts on hydrological processes. Some of the changes are linked to soil properties modification, directly disturbing water infiltration and runoff generation processes, which affects local and regional water resources. Although there has been considerable research on soil properties, few studies focused its spatial and temporal variability at the catchment scale and how they affect hydrology. In this paper, we aim to assess the spatial and temporal variability of water repellence, soil moisture and water infiltration, in a small catchment under Mediterranean climate. The study was carried out at Ribeira dos Covões, a small catchment (620ha) located in central Portugal. This is a partly urbanizing catchment, where the urban landuse covers 32% of the area, while the forest represent 48% and farmland 20%. The catchment has a sub-humid Mediterranean climate, with long dry summers. The soil is deep overlaying sandstone and limestone lithology. Thirty one representative sites were monitored within the catchment. Each site has two replicated experiments for water infiltration (performed during 30 minutes, through minidisk tension infiltrometer at the soil surface), soil moisture content (at 0-5cm depth, by gravimetric method) and soil water repellence (assessed at 0cm, 2cm and 5cm depth through ethanol percentage test). These experiments were carried out along one entire year, during nine monitoring campaigns performed in dry and wet periods, mainly immediately after different rainfall events and long dry spells. During one of the monitoring campaigns, undisturbed soil samples were collected (0-10cm depth) in all the location sites for bulk density and stone content analyses. Composite samples were also collected from the top soil layer (0-5cm and 5-10cm) for organic content (by measuring carbon dioxide emission after combustion at 1200

  4. 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.

  5. Chrysanthemum CmNAR2 interacts with CmNRT2 in the control of nitrate uptake

    PubMed Central

    Gu, Chunsun; Zhang, Xiaoxue; Jiang, Jiafu; Guan, Zhiyong; Zhao, Shuang; Fang, Weimin; Liao, Yuan; Chen, Sumei; Chen, Fadi

    2014-01-01

    Nitrate transporters are an important component of plant growth and development. Chrysanthemum morifolium is an important ornamental species, for which a sufficient supply of nitrogenous fertilizer is required to maintain economic yields. In this study, the full-length cDNA of the nitrate transporter genes CmNRT2 and CmNAR2 were isolated. CmNRT2 transcript accumulation was inducible by both nitrate and ammonium, but the latter ion down-regulated the transcript accumulation of CmNAR2. CmNRT2 might be a plasma membrane localized protein, while CmNAR2 was distributed throughout the cell. CmNAR2 was shown to interact with CmNRT2 by in vitro and in vivo assays. Arabidopsis thaliana plants heterologously expressing CmNRT2 showed an increased rate of nitrate influx, while this trait was unaltered in plants expressing CmNAR2. Double transformants (CmNRT2 plus CmNAR2) exhibited an enhanced rate of nitrate influx into the root. Our data indicated that the interaction of CmNAR2 with CmNRT2 contributed to the uptake of nitrate. PMID:25060485

  6. Surface photovoltage investigations of Cd 1-xMn xTe for x = 0.01 and 0.10

    NASA Astrophysics Data System (ADS)

    Kuźmiński, S.; Szaynok, A. T.

    1988-07-01

    Surface photovoltage investigations of Cd 1- xMn xTe monocrystals for x = 0.01 and 0.10 were performed in the temperature range between 100 and 300 K with a modified Kelvin method at a pressure of 10 -5 Pa. The surfaces with orientation (110) were ground, polished with "Gamal", and rinsed in acetone and alcohol. Three types of effects were observed on the surface spectroscopy curves: A sharp increase in photovoltage, connected with the electron band-to-band transitions for a photon energy equal to the energy gap. Photovoltage quenching attributed to the existence of surface states with energy just above the edge of the valence band. Increase in photovoltage in the range between 0.9 and 1.0 eV resulting from electron transitions between the valence band and energy states connected with manganese ions.

  7. Investigation of dielectric and electrical behaviour of nanocrystalline Zn1-xMnxO (x=0 to 0.10) semiconductors synthesized by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Choudhury, S.; Sain, S.; Mandal, M. K.; Pradhan, S. K.; Meikap, A. K.

    2016-07-01

    The results on the measurement of electric and dielectric behaviour and capacitance-voltage characteristics of Zn1-xMnxO (x=0 to 0.10) nanocrystalline semiconductors are reported. Direct current conductivity increases with the increase Mn concentration and its thermal behavior can be explained by adiabatic polaronic hopping model. The alternating current conductivity obeys a power law of temperature and frequency. The temperature exponent p strongly depends on Mn concentration. The temperature dependence of frequency exponent s suggests that the overlapping large polaron conduction model is the appropriate conduction mechanism for the investigated samples. The interfacial boundaries and grain contribution to the dielectric properties can be identified by the analysis of complex impedance. Relaxation behaviour of the samples can be explained from the analysis of the electric modulus. Formation of Schottky diode can be described from capacitance-voltage characteristic of the samples and different diode parameters can be extracted from it.

  8. Influence of sodium doping on the electrical and magnetic properties of La0.90Li0.10MnO3 manganites

    NASA Astrophysics Data System (ADS)

    Mohamed, H. F.

    2017-02-01

    Monovalent perovskite manganites La0.90Li0.10-xNaxMnO3 were synthesized by using the solid-state reaction method. The crystal structure analysis presented that the samples are a single-phase rhombohedral (R 3 bar c) structure with no detectable impurity phases. Magnetic measurement showed a cusp at a certain temperature TC/F that gradually disappeared with adding the Na content. The samples undergo ferromagnetic-paramagnetic transition, accompanying the metal-semiconductor transition at Tms. There is irreversible on low field M (T)ZFC and M (T)FC curves which gradual decrease with increasing the Na doping. The resistivity values decreased and the Tms increased as doping of sodium increased. In addition, two-transition temperature Tms appeared just by adding the sodium. In short, the influence of partial substitution of lithium by sodium at A-site cation of lanthanum manganite on its physical properties was studied.

  9. Reactions in 1,1,1-trifluoroacetone triggered by low energy electrons (0-10 eV): from simple bond cleavages to complex unimolecular reactions.

    PubMed

    Illenberger, Eugen; Meinke, Martina C

    2014-08-21

    The impact of low energy electrons (0-10 eV) to 1,1,1-trifluoroacetone yields a variety of fragment anions which are formed via dissociative electron attachment (DEA) through three pronounced resonances located at 0.8 eV, near 4 eV, and in the energy range 8-9 eV. The fragment ions arise from different reactions ranging from the direct cleavage of one single or double bond (formation of F(-), CF3(-), O(-), (M-H)(-), and M-F)(-)) to remarkably complex unimolecular reactions associated with substantial geometric and electronic rearrangement in the transitory intermediate (formation of OH(-), FHF(-), (M-HF)(-), CCH(-), and HCCO(-). The ion CCH(-), for example, is formed by an excision of unit from the target molecule through the concerted cleavage of four bonds and recombination to H2O within the neutral component of the reaction.

  10. Ozone-concentration and pulmonary-response relationships for 6. 6-hour exposures with five hours of moderate exercise to 0. 08, 0. 10, and 0. 12 ppm

    SciTech Connect

    Horstman, D.H.; Folinsbee, L.J.; Ives, P.J.; Salaam, S.A.; McDonnell, W.F.

    1990-01-01

    The magnitudes of pulmonary responses the authors previously observed (1) following 6.6-h exposure to 0.12 ppm ozone (O{sub 3}) suggested that responses would also occur with similar exposures at lower O{sub 3} concentrations. The objective of the study was to determine the extent of pulmonary function decrements, respiratory discomfort, and increased airway reactivity to methacholine induced by exposure to O{sub 3} below 0.12 ppm. Separate 6.6-h chamber exposures to 0.00, 0.08, 0.10, and 0.12 ppm O3 included six 50-min periods of moderate exercise (VE = 39 L/min, HR = 115 bpm, and VO2 = 1.5 L/min). Each exercise period was followed by 10 min of rest. A 35-min lunch break was included midway through the exposure. Although not intended as an exact simulation, the overall duration, intensity, and metabolic requirements of the exercise performed were representative of a day of moderate to heavy work or play. Preexposure FEV, averaged 4.39 L, and essentially no change (+0.03 L) occurred with exposure to 0.00 ppm O{sub 3}. Significant decreases (p<0.01) of -0.31, -0.30, and -0.54 L were observed with exposures to 0.08, 0.10, and 0.12 ppm, respectively. The study concludes that exposure to O{sub 3} at levels often found in ambient air while engaged in activity representative of a typical day of moderate to heavy work or play induced clinically meaningful pulmonary responses.

  11. C and N content in density fractions of whole soil and soil size fraction under cacao agroforestry systems and natural forest in Bahia, Brazil.

    PubMed

    Rita, Joice Cleide O; Gama-Rodrigues, Emanuela Forestieri; Gama-Rodrigues, Antonio Carlos; Polidoro, Jose Carlos; Machado, Regina Cele R; Baligar, Virupax C

    2011-07-01

    Agroforestry systems (AFSs) have an important role in capturing above and below ground soil carbon and play a dominant role in mitigation of atmospheric CO(2). Attempts has been made here to identify soil organic matter fractions in the cacao-AFSs that have different susceptibility to microbial decomposition and further represent the basis of understanding soil C dynamics. The objective of this study was to characterize the organic matter density fractions and soil size fractions in soils of two types of cacao agroforestry systems and to compare with an adjacent natural forest in Bahia, Brazil. The land-use systems studied were: (1) a 30-year-old stand of natural forest with cacao (cacao cabruca), (2) a 30-year-old stand of cacao with Erythrina glauca as shade trees (cacao + erythrina), and (3) an adjacent natural forest without cacao. Soil samples were collected from 0-10 cm depth layer in reddish-yellow Oxisols. Soil samples was separated by wet sieving into five fraction-size classes (>2000 μm, 1000-2000 μm, 250-1000 μm, 53-250 μm, and <53 μm). C and N accumulated in to the light (free- and intra-aggregate density fractions) and heavy fractions of whole soil and soil size fraction were determined. Soil size fraction obtained in cacao AFS soils consisted mainly (65 %) of mega-aggregates (>2000 μm) mixed with macroaggregates (32-34%), and microaggregates (1-1.3%). Soil organic carbon (SOC) and total N content increased with increasing soil size fraction in all land-use systems. Organic C-to-total N ratio was higher in the macroaggregate than in the microaggregate. In general, in natural forest and cacao cabruca the contribution of C and N in the light and heavy fractions was similar. However, in cacao + erythrina the heavy fraction was the most common and contributed 67% of C and 63% of N. Finding of this study shows that the majority of C and N in all three systems studied are found in macroaggregates, particularly in the 250-1000 μm size

  12. C and N Content in Density Fractions of Whole Soil and Soil Size Fraction Under Cacao Agroforestry Systems and Natural Forest in Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    Rita, Joice Cleide O.; Gama-Rodrigues, Emanuela Forestieri; Gama-Rodrigues, Antonio Carlos; Polidoro, Jose Carlos; Machado, Regina Cele R.; Baligar, Virupax C.

    2011-07-01

    Agroforestry systems (AFSs) have an important role in capturing above and below ground soil carbon and play a dominant role in mitigation of atmospheric CO2. Attempts has been made here to identify soil organic matter fractions in the cacao-AFSs that have different susceptibility to microbial decomposition and further represent the basis of understanding soil C dynamics. The objective of this study was to characterize the organic matter density fractions and soil size fractions in soils of two types of cacao agroforestry systems and to compare with an adjacent natural forest in Bahia, Brazil. The land-use systems studied were: (1) a 30-year-old stand of natural forest with cacao (cacao cabruca), (2) a 30-year-old stand of cacao with Erythrina glauca as shade trees (cacao + erythrina), and (3) an adjacent natural forest without cacao. Soil samples were collected from 0-10 cm depth layer in reddish-yellow Oxisols. Soil samples was separated by wet sieving into five fraction-size classes (>2000 μm, 1000-2000 μm, 250-1000 μm, 53-250 μm, and <53 μm). C and N accumulated in to the light (free- and intra-aggregate density fractions) and heavy fractions of whole soil and soil size fraction were determined. Soil size fraction obtained in cacao AFS soils consisted mainly (65 %) of mega-aggregates (>2000 μm) mixed with macroaggregates (32-34%), and microaggregates (1-1.3%). Soil organic carbon (SOC) and total N content increased with increasing soil size fraction in all land-use systems. Organic C-to-total N ratio was higher in the macroaggregate than in the microaggregate. In general, in natural forest and cacao cabruca the contribution of C and N in the light and heavy fractions was similar. However, in cacao + erythrina the heavy fraction was the most common and contributed 67% of C and 63% of N. Finding of this study shows that the majority of C and N in all three systems studied are found in macroaggregates, particularly in the 250-1000 μm size aggregate class

  13. Arbuscular mycorrhizal fungi associated with vegetation and soil parameters under rest grazing management in a desert steppe ecosystem.

    PubMed

    Bai, Gegenbaoleer; Bao, Yuying; Du, Guoxin; Qi, Yunlong

    2013-05-01

    The impact of rest grazing on arbuscular mycorrhizal fungi (AMF) and the interactions of AMF with vegetation and soil parameters under rest grazing condition were investigated between spring and late summer in a desert steppe ecosystem with different grazing managements (rest grazing with different lengths of resting period, banned or continuous grazing) in Inner Mongolia, China. AMF diversity and colonization, vegetation biomass, soil properties and soil phosphatase activity were examined. In rest grazing areas of 60 days, AMF spore number and diversity index at a 0-10 cm soil depth as well as vesicular and hyphal colonization rates were higher compared with other grazing treatments. In addition, soil organic matter and total N contents were highest and soil alkaline phosphatase was most active under 60-day rest grazing. In August and September, these areas also had the highest amount of aboveground vegetation. The results indicated that resting grazing for an appropriate period of time in spring has a positive effect on AMF sporulation, colonization and diversity, and that under rest grazing conditions, AMF parameters are positively correlated with some soil characteristics.

  14. High charge-discharge performance of Pb0.98La0.02(Zr0.35Sn0.55Ti0.10)0.995O3 antiferroelectric ceramics

    NASA Astrophysics Data System (ADS)

    Xu, Chenhong; Liu, Zhen; Chen, Xuefeng; Yan, Shiguang; Cao, Fei; Dong, Xianlin; Wang, Genshui

    2016-08-01

    The energy storage performance and charge-discharge properties of Pb0.98La0.02(Zr0.35Sn0.55Ti0.10)0.995O3 (PLZST) antiferroelectric ceramics were investigated through directly measuring the hysteresis loops and pulse discharge current-time curves. The energy density only varies 0.2% per degree from 25 °C to 85 °C, and the energy efficiency maintains at about 90%. Furthermore, an approximate calculating model of maximum power density pmax was established for the discharge process. Under a relatively high working electric field (8.2 kV/mm), this ceramics possess a greatly enhanced power density of 18 MW/cm3. Moreover, the pulse power properties did not show degradation until 1500 times of charge-discharge cycling. The large released energy density, high energy efficiency, good temperature stability, greatly enhanced power density, and excellent fatigue endurance combined together make this PLZST ceramics an ideal candidate for pulse power applications.

  15. Carbon storage potential in size-density fractions from semi-natural grassland ecosystems with different productivities over varying soil depths.

    PubMed

    Breulmann, Marc; Boettger, Tatjana; Buscot, François; Gruendling, Ralf; Schulz, Elke

    2016-03-01

    Researchers have increasingly recognised a profound need for more information on SOC stocks in the soil and the factors governing their stability and dynamics. Many questions still remain unanswered about the interplay between changes in plant communities and the extent to which changes in aboveground productivity affect the carbon dynamics in soils through changes in its quantity and quality. Therefore, the main aim of this research was to examine the SOC accumulation potential of semi-natural grasslands of different productivities and determine the distribution of SOM fractions over varying soil depth intervals (0-10, 10-20, 20-30 30-50 50-80 and 80+cm). SOM fractionation was considered as a relative measure of stability to separate SOM associated with clay minerals from SOM of specific light densities less than 2 g cm(-3) (size-density fractionation). Two clay-associated fractions (CF1, <1 μm; and CF2, 1-2 μm) and two light fractions (LF1, <1.8 g cm(-3); and LF2, 1.8-2.0 g cm(-3)) were separated. The stability of these fractions was characterised by their carbon hot water extractability (CHWE) and stable carbon isotope composition. In the semi-natural grasslands studied, most OC was stored in the top 30 cm, where turnover is rapid. Effects of low productivity grasslands became only significantly apparent when fractional OC contributions of total SOM was considered (CF1 and LF1). In deeper soil depths OC was largely attributed to the CF1 fraction of low productivity grasslands. We suggest that the majority of OM in deeper soil depth intervals is microbially-derived, as evidenced by decreasing C/N ratios and decreasing δ(13)C values. The hot water extraction and natural δ(13)C abundance, employed here allowed the characterisation of SOM stabilisation properties, however how climatic changes affect the fate of OM within different soil depth intervals is still unknown.

  16. [Diversity of soil fauna in corn fields in Huang-Huai-Hai Plain of China under effects of conservation tillage].

    PubMed

    Zhu, Qiang-Gen; Zhu, An-Ning; Zhang, Jia-Bao; Zhang, Huan-Chao; Huang, Ping; Zhang, Cong-Zhi

    2009-10-01

    An investigation was made on the abundance and diversity of soil fauna in the corn fields under conventional and conservation tillage in Huang-Huai-Hai Plain of China. The abundance and diversity of soil fauna were higher at corn maturing (September) than at its jointing stage (July), and higher at jointing stage under conservation tillage than under conventional tillage. Soil fauna mainly distributed in surface soil layer (0-10 cm), but still had a larger number in 10-20 cm layer under conservation tillage. The individuals of acari, diptera, diplura, and microdrile oligochaetes, especially those of acari, were higher under conservation tillage than under conventional tillage. At maturing stage, an obvious effect of straw-returning under conservation tillage was observed, i. e., the more the straw returned, the higher the abundance of soil fauna, among which, the individuals of collembola, acari, coleopteran, and psocoptera, especially those of collembolan, increased significantly. The abundance of collembola at both jointing and maturing stages was significantly positively correlated with the quantity of straw returned, suggesting that collembola played an important role in straw decomposition and nutrient cycling.

  17. MCNP ESTIMATE OF THE SAMPLED VOLUME IN A NON-DESTRUCTIVE IN SITU SOIL CARBON ANALYSIS.

    SciTech Connect

    WIELOPOLSKI, L.; DIOSZEGI, I.; MITRA, S.

    2004-05-03

    Global warming, promoted by anthropogenic CO{sub 2} emission into the atmosphere, is partially mitigated by the photosynthesis processes of the terrestrial echo systems that act as atmospheric CO{sub 2} scrubbers and sequester carbon in soil. Switching from till to no till soils management practices in agriculture further augments this process. Carbon sequestration is also advanced by putting forward a carbon ''credit'' system whereby these can be traded between CO{sub 2} producers and sequesters. Implementation of carbon ''credit'' trade will be further promulgated by recent development of a non-destructive in situ carbon monitoring system based on inelastic neutron scattering (INS). Volumes and depth distributions defined by the 0.1, 1.0, 10, 50, and 90 percent neutron isofluxes, from a point source located at either 5 or 30 cm above the surface, were estimated using Monte Carlo calculations.

  18. [Effects of degraded sandy grassland afforestation on soil quality in semi-arid area of northern China].

    PubMed

    Hu, Ya-lin; Zeng, De-hui; Fan, Zhi-ping; Ai, Gui-yan

    2007-11-01

    By the methods of field survey and incubation test, this paper studied the effects of degraded sandy grassland afforestation with Mongolian pine on the soil physical, chemical and biological properties in 0-10 cm layer on Keerqin sandy land. The results showed that after 32 years afforestation, soil organic C, total N and total P decreased by 21%, 42% and 45%, respectively. In May and November, soil NH4+ -N content was significantly higher under Mongolian pine plantation than under grassland (P = 0.001; P = 0.019), but in May, August and November, soil NO3- -N content was in adverse (P < 0.001; P = 0.048; P = 0.031). In May, August and November, soil C mineralization rate was higher under Mongolian pine plantation than under grassland, but the difference in N mineralization rate was not significant (P > 0.05). In May and August, soil microbial biomass C under Mongolian pine plantation and grassland had little difference, but in November, it was significantly higher under Mongolian pine plantation than under grassland. Soil nutrients- and moisture contents were the important factors affecting soil microbial biomass C. Soil urease and invertase activities decreased but catalase activity increased under Mongolian pine plantation, compared with those under grassland. It was suggested that 32 years afforestation of degraded sandy grassland with Mongolian pine on Keerqin sandy land led to a definite degradation of soil quality. Owing to the changes of vegetation, the test indicators of soil quality had different seasonal dynamic characteristics under Mongolian pine plantation and grassland. As a means of degraded ecosystem restoration in semi-arid area of Northern China, afforestation had its definite limitations.

  19. CO(2) and N(2)O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica.

    PubMed

    Thomazini, A; Mendonça, E S; Teixeira, D B; Almeida, I C C; La Scala, N; Canellas, L P; Spokas, K A; Milori, D M B P; Turbay, C V G; Fernandes, R B A; Schaefer, C E G R

    2015-07-15

    Studies of C cycle alterations are extremely important to identify changes due to climate change, especially in the polar ecosystem. The objectives of this study were to (i) examine patterns of soil CO2-C and N2O-N emissions, and (ii) evaluate the quantity and quality of soil organic matter across a glacier retreat chronosequence in the Maritime Antarctica. Field measurements were carried out during January and February 2010 (summer season) along a retreating zone of the White Eagle Glacier, at King George Island, Maritime Antarctica. Soil samples (0-10cm) were collected along a 500-m transect at regular intervals to determine changes in soil organic matter. Field CO2-C emission measurements and soil temperature were carried out at regular intervals. In addition, greenhouse gas production potentials were assessed through 100days laboratory incubations. Soils exposed for a longer time tended to have greater concentrations of soluble salts and possess sandier textures. Total organic C (3.59gkg(-1)), total N (2.31gkg(-1)) and labile C (1.83gkg(-1)) tended to be lower near the glacier front compared with sites away from it, which is correlated with decreasing degree of humification of the soil organic matter with exposure time. Soil CO2-C emissions tended to increase with distance from the glacier front. On average, the presence of vegetation increased CO2-C emissions by 440%, or the equivalent of 0.633g of CO2-C m(-2)h(-1). Results suggest that newly exposed landsurfaces undergo soil formation with increasing labile C input from vegetation, accompanied by increasing soil CO2-C emissions. Despite the importance of exposure time on CO2-C production and emissions, there was no similar trend in soil N2O-N production potentials as a function of glacial retreat. For N2O, instead, the maximum production occurred in sites with the first stages of vegetation growth.

  20. The effects of extreme rainfall events on carbon release from Biological Soil Crusts covered soil in fixed sand dunes in the Tengger Desert, northern China

    NASA Astrophysics Data System (ADS)

    Zhao, Yang; Li, Xinrong; Pan, Yanxia; Hui, Rong

    2016-04-01

    How soil cover types and extreme rainfall event influence carbon (C) release in temperate desert ecosystems has largely been unexplored. We assessed the effects of extreme rainfall (quantity and intensity) events on the carbon release from soils covered by different types of biological soil crusts (BSCs) in fixed sand dunes in the Tengger Desert, Shapotou regionof northern China. We removed intact crusts down to 10 cm and measured them in PVC mesocosms. A Li-6400-09 Soil Chamber was used to measure the respiration rates of the BSCs immediately after the rainfall stopped, and continued until the respiration rates of the BSCs returned to the pre-rainfall basal rate. Our results showed that almost immediately after extreme rainfall events the respiration rates of algae crust and mixed crust were significantly inhibited, but moss crust was not significantly affected. The respiration rates of algae crust, mixed crust, and moss crust in extreme rainfall quantity and intensity events were, respectively, 0.12 and 0.41 μmolCO2/(m2•s), 0.10 and 0.45 μmolCO2/(m2•s), 0.83 and 1.69 μmolCO2/(m2•s). Our study indicated that moss crust in the advanced succession stage can well adapt to extreme rainfall events in the short term. Keywords: carbon release; extreme rainfall events; biological soil crust

  1. Evaluation of the Performance of HYDRUS-2D in Simulating Effects of Shading and Irrigation on Soil Water Content and Temperature

    NASA Astrophysics Data System (ADS)

    Fares, A.; Simunek, J.; Parsons, L. R.; van Genuchten, T. M.; Wheaton, T. A.; Morgan, K. T.

    2001-12-01

    Citrus root systems are exposed to different thermal and hydrologic conditions as a result of tree canopy shading and undertree microirrigation. Because microsprinklers wet only part of the soil surface and are located under the tree, roots under the canopy usually receive more water than those outside the tree canopy. The combined effects of different soil temperature and water input on water redistribution under field conditions have not been fully studied in Florida sandy soils. The objective of this study was to investigate shading and irrigation effects on spatial distribution of water content and soil temperature at different soil depths. Real-time capacitance probe systems (EnviroSCAN, SENTEK, Ltd. South Australia) and thermocouples were used to monitor soil water content and temperature at depths of 0, 10, 20, 40, 80 and 150 cm. Weather parameters were monitored simultaneously at the same location. HYDRUS-2D, a two dimensional computer package for simulating movement of water, heat, and multiple solutes in variably saturated media, was used to simulate water flow and heat transport under such conditions. The predicted water contents and soil temperatures compared favorably with their corresponding observed parameters. Shading substantially influenced hydraulic and thermal regimes of the system as shown by both predicted and measured water content and soil temperature. In addition to its accuracy in simulating this system, HYDRUS-2D helped to improve the analysis of this research project.

  2. 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.

  3. Towards a default soil carbon sequestration rate after cropland to Miscanthus conversion in Europe

    NASA Astrophysics Data System (ADS)

    Poeplau, Christopher; Don, Axel

    2013-04-01

    In Europe, an estimated 17-21 million hectares (Mha) of land will need to be converted to bioenergy crop production to meet the EU bioenergy targets for 2020. Conventional bioenergy crops, such as maize and oilseed rape, are known for high greenhouse gas emissions. Perennial grases, such as Miscanthus, are seen as sustainable alternative, due to low fertilizer demand, relatively high yields and the potential to sequester soil organic carbon (SOC). However, the variability of currently published SOC stock changes is huge, ranging from -6.8 to +7.7 Mg ha-1 yr-1, which we attribute to different organic manure applications and differences in the baseline SOC stocks between the sampled plots in the paired plot approach. The conversion from cropland to Miscanthus involves a C3-C4 vegetation change, which allows following the incorporation of C4 Miscanthus-derived carbon into the soil by measuring the abundance of the stable isotope 13C. This was done for six different Miscanthus plantations across Europe, which were older than ten years. C3 carbon decomposition was estimated using the carbon turnover model RothC. Both, C4 and C3 carbon dynamics were summed to obtain the vegetation change-induced SOC stock change. We subsequently applied this approach to all European sites, where C4 carbon dynamic after cropland to Miscanthus conversion has been investigated (n=14) and derived a temperature dependant SOC sequestration rate. We found a mean annual accumulation of 0.40±0.20 Mg C ha-1. Furthermore, we conducted a SOC fractionation to assess the incorporation of C4 carbon into different SOC fractions. After a mean time of 16 years, the particulate organic matter (POM) fraction consisted of 68% Miscanthus-derived carbon in 0-10 cm soil depth. The NaOCl resistant fraction, which is considered "inert", consisted of 12% Miscanthus-derived carbon in 0-10 cm soil depth.

  4. Structural and dynamic electromagnetic properties of Ni0.27 Cu0.10 Zn0.63 Alx Fe2-x O4

    NASA Astrophysics Data System (ADS)

    Hossen, M. Belal; Hossain, A. K. M. Akther

    2015-08-01

    The influence of Al substitution on the structural and electromagnetic properties of Ni0.27Cu0.10Zn0.63AlxFe2 - xO4; (where x = 0.0 to x = 0.16 with step = 0.02) prepared by the combustion technique, has been investigated. X-ray diffraction analysis confirms the presence of single phase cubic spinel structure without any secondary phase. The lattice constant, theoretical density, bulk density and average grain size decreases with increasing Al content. B-H loops have been traced for all the compositions and the various hysteresis parameters like saturation induction, coercivity, remanance, remanance ratio and power loss have been studied as a function of Al content. The saturation induction and the initial permeability increases with sintering temperature up to 1150 °C where the maximum bulk density is obtained, while for higher sintering temperature they decrease. The variation of complex initial permeability for Al substituted NiCuZn ferrites can be presented as a form of semicircle so called the Cole-Cole plot and the relaxation phenomena were explained with various shapes of the plots. The analysis of complex impedance spectra by an equivalent circuit model were used to separate the grain and grain boundary resistance of various Ni0.27 Cu0.10 Zn0.63 Alx Fe2 - x O4 . The impedance plot showed the first semicircle at high frequency which corresponds to grain effect and the second semicircle at lower frequency which corresponds to grain boundary (conduction phenomenon). Both grain and grain boundary resistance increases with increasing Al content and the relative increase of grain resistance is larger than the grain boundary resistance. The frequency dependent conductivity results support the double (Jonscher's modified) power law,σT (ω) = σ (o) +A1 ω n1 +A2 ω n2 , and the results showed evidence of three types of conduction process at room temperature: (i) low frequency conductivity is due to long-range ordering (frequency independent or its tendency

  5. Metal distribution in urban soil around steel industry beside Queen Alia Airport, Jordan.

    PubMed

    Al-Khashman, Omar A; Shawabkeh, Reyad A

    2009-12-01

    The objective of this study was to assess the extent and severity of metal contamination in urban soil around Queen Alia Airport, Jordan. Thirty-two soil samples were collected around steel manufacturing plants located in the Al-Jiza area, south Jordan, around the Queen Alia Airport. The samples were obtained at two depths, 0-10 and 10-20 cm, and were analyzed by atomic absorption spectrophotometry for lead (Pb), zinc (Zn), cadmium (Cd), iron (Fe), copper (Cu) and chromium (Cr) levels. The physicochemical factors believed to affect the mobility of metals in the soil of the study area were also examined, including pH, electrical conductivity, total organic matter, calcium carbonate (CaCO(3)) content and cation exchange capacity. The high concentrations of Pb, Zn and Cd in the soil samples were found to be related to anthropogenic sources, such as the steel manufacturing plants, agriculture and traffic emissions, with the highest concentrations of these metals close to the site of the steel plants; in contrast the concentration of Cr was low in the soil sampled close to the steel plants. The metals were concentrated in the surface soil, and concentrations decreased with increasing depth, reflecting the physical properties of the soil and its alkaline pH. The mineralogical composition of the topsoil, identified by X-ray diffraction, was predominantly quartz, calcite, dolomite and minor minerals, such as gypsum and clay minerals. Metal concentrations were compared using one-way analysis of variance (ANOVA) to compute the statistical significance of the mean. The results of the ANOVA showed significant differences between sites for Pb, Cd and Cu, but no significant differences for the remaining metals tested. Factor analysis revealed that polluted soil occurs predominantly at sites around the steel plants and that there is no significant variation in the characteristics of the unpolluted soil, which are uniform in the study area.

  6. Soil phosphorus mobility and solid-to-solution phase resupply studied by diffusive gradients in thin films: background soil properties driving their variation

    NASA Astrophysics Data System (ADS)

    Menezes-Blackburn, Daniel; Zhang, Hao; Giles, Courtney; George, Timothy; Shand, Charlie; Lumsdon, David; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Stutter, Marc; Blackwell, Martin; Darch, Tegan; Wearing, Catherine; Philip, Haygarth

    2015-04-01

    The mobility and resupply of inorganic phosphorus (P) from the solid phase was studied in 32 representative soils from the UK. The objective was to identify the background soil properties driving the variation of soil inorganic P desorption kinetics across different soil types. Diffusive gradients in thin films (DGT), diffusive equilibration in thin films (DET) and the DGT-induced fluxes in sediments model (DIFS) were used as tools for exploring solid-to-solution desorption kinetics. Previously characterized physicochemical properties of the same soils were used for correlation analysis. On average and across soil types, the inorganic P maximum distance of depletion was 0.42±0.10 cm, the equilibration time (Tc) was 3.63 h, the desorption rate constant (k-1) was 0.0046 h-1, and the desorption rate was 4.71 nmol l-1 s-1. The correlation between P in Olsen extractcs (POlsen) with PDGT, PDET and phosphorus effective concentration (PE) was enhanced when similar soils were isolated and used in the comparison, clearly showing that these parameters are affected differently by soil types. The PE was better correlated to Ptot, POlsen, PFeO, and PNaOH/EDTA than PDGT. This may indicate that PE is a better representation of P availability across soil types than PDGT. While the relative DGT-induced inorganic P flux in the first hour is mainly a function of soil wetting properties and % Corg, at longer times it is a function of the resupply capacity (R-Rdiff) of the soil solid phase. In general, resupply of P from the solid phase was less than that for other chemical elements, as shown by high Tc and low k-1 values. Desorption rates and resupply from the solid phase were fundamentally influenced by P saturation status, as reflected by their strong correlation with P concentration in water, FeO strips, Olsen and NaOH-EDTA extracts. Soil pH and particle size distribution had little or no effect on the evaluated parameters. The DGT and DET techniques, along with the DIFS model

  7. Pressure distributions obtained on a 0.10-scale model of the Space Shuttle Orbiter's forebody in the Ames Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Siemers, P. M., III; Henry, M. W.

    1986-01-01

    Pressure distribution test data obtained on a 0.10-scale model of the forward fuselage of the Space Shuttle Orbiter are presented without analysis. The tests were completed in the Ames Unitary Wind Tunnel (UPWT). The UPWT tests were conducted in two different test sections operating in the continuous mode, the 8 x 7 feet and 9 x 7 feet test sections. Each test section has its own Mach number range, 1.6 to 2.5 and 2.5 to 3.5 for the 9 x 7 feet and 8 x 7 feet test section, respectively. The test Reynolds number ranged from 1.6 to 2.5 x 10 to the 6th power ft and 0.6 to 2.0 x 10 to the 6th power ft, respectively. The tests were conducted in support of the development of the Shuttle Entry Air Data System (SEADS). In addition to modeling the 20 SEADS orifices, the wind-tunnel model was also instrumented with orifices to match Development Flight Instrumentation (DFI) port locations that existed on the Space Shuttle Columbia (OV-102) during the Orbiter Flight test program. This DFI simulation has provided a means for comparisons between reentry flight pressure data and wind-tunnel and computational data.

  8. Effect of yttrium on microstructure, dielectric, ferroelectric and optical properties of BaZr0.10Ti0.90O3 nanoceramics

    NASA Astrophysics Data System (ADS)

    Kumar Patel, Piyush; Yadav, K. L.

    2014-06-01

    Y3+ doped barium zirconium titanate Ba(1-3x/2)Yx(Zr0.10Ti0.90)O3 ceramics were synthesized by the sol-gel method. Single phase compounds were confirmed by X-ray diffraction. Morphological analysis shows that the addition of Y3+ content inhibits the grain growth and remarkably changes the dielectric and ferroelectric properties. The temperature dependence of dielectric constant shows a change due to the material's diffuse phase transition, with a shift of the Curie temperature towards room temperature. High dielectric constant (~7937) with low dielectric loss (~0.05) was found for x=0.01 composition at Curie temperature. The diffusivity parameter was calculated as a function of Y3+ content and diffuseness was found to increase with increasing Y3+ content. The remnant polarization shows a slight increase up to x=0.01 composition and then decreases with increasing Y3+ content. The UV-visible optical absorption spectra show that the band gap increases from 3.71 eV to 3.96 eV with increasing Y3+ content.

  9. Structural and dielectric studies of Bi (Ni0.45Ti0.45Fe0.10) O3 ceramics

    NASA Astrophysics Data System (ADS)

    Kumar, Nitin; Shukla, Alok; Choudhary, R. N. P.; Behera, C.

    2016-05-01

    In the present investigation, a solid solution of BiFeO3 and NiTiO3 i.e., Bi(Ni0.45Ti0.45Fe0.10)O3 (abbreviation is BNTF) have been synthesized using a solid-state reaction technique. Structural and dielectric properties of BNTF ceramics have been studied in details to understand their properties. Preliminary X-ray diffraction analysis confirm the formation of a new system, which is different from that of its parent compounds. Substitution of a small amount of NiTiO3 into BiFeO3 enhances dielectric and ferroelectric properties, and reduces electrical leakage current or tangent loss. It was shown by XRD that at room temperature structure of the compound is of single-phase with tetragonal symmetry. Some electrical characteristics (dielectric constant and loss) studied over a wide frequency (1 kHz-1 MHz) and temperature (25-400°C) ranges have provided many more interesting information useful for devices.

  10. Identifying the sources of ferromagnetism in sol-gel synthesized Zn1-xCoxO (0≤x≤0.10) nanoparticles

    NASA Astrophysics Data System (ADS)

    Beltrán, J. J.; Barrero, C. A.; Punnoose, A.

    2016-08-01

    We have carefully investigated the structural, optical and electronic properties and related them with changes in the magnetism of sol-gel synthesized Zn1-xCoxO (0≤x≤0.10) nanoparticles. Samples with x≤0.05 were free of spurious phases. Samples with x≤0.03 were found to be with only high spin Co2+ ions into ZnO structure, whereas sample with x=0.05, exhibited the presence of high spin Co2+ and low spin Co3+. We found that the intensity of the main EPR peak associated with Co2+ varies with the nominal Co content in a similar manner as the saturation magnetization and coercive field do. These results point out that the ferromagnetism in these samples should directly be correlated with the presence of divalent cobalt ions. Bound magnetic polaron (BMP) model and the charge transfer model are insufficient to explain the ferromagnetic properties of Zn1-xCoxO nanoparticles. The room temperature ferromagnetism (RTFM) may be originated from a combination of several factors such as the interaction of high spin Co2+ ions, perturbation/alteration and/or changes in the electronic structure of ZnO close to the valence band edge and grain boundary effects.

  11. Spatial Patterns and Topographic Controls of Post-settlement Deposition and Soil Organic Carbon Storage in Depressional Landscapes of Minnesota

    NASA Astrophysics Data System (ADS)

    Wu, A.; Bell, J.; Nater, E.

    2013-12-01

    Agriculture-enhanced erosion and deposition affect soil organic carbon (SOC) dynamics and storage on hillslopes. Because soil is the largest terrestrial C inventory, such SOC change can have significant impacts on global C cycling. The downslope deposition and burial of C-rich topsoils in depressional landscapes are likely to sequester SOC, but our understanding of the spatial patterns and mechanisms behind it is still limited. In this study, we aim to identify spatial distribution of post-settlement deposition and SOC and to understand its physical impact on soil C storage in depressional landscapes on the Des Moines Lobe in Minnesota. The specific objectives for this study are to: 1) understand the distribution and thickness of post-settlement deposition by building spatial soil-landscape models using local and upslope dependence area terrain attributes; 2) develop soil C models for various profile depths; and 3) identify the spatial relation between post-settlement deposition and SOC. Using a 1-m LiDAR-based digital elevation model, we apply upslope dependence (contributing areas) and local (3-by-3 cell window) terrain attributes in spatial modeling because topographic features are key factors controlling landscape-scale soil processes. Upslope dependence terrain drives the waterflow-relevant soil processes such as soil erosion production, and local terrain controls redeposition. We predict the spatially-explicit probability of post-settlement deposition presence using logistic regression, and employ multiple linear regressions for the prediction of its thickness. Because the depth distribution of SOC in soil is affected by biological activities and topographic controls, we interpolated and mapped the spatial distribution of SOC in five fixed-depth layers (0-10cm, 10-30cm, 30-60cm, 60-90cm, and 90-120cm) and reported full depth composite values after individual layer modeling. The resulting SOC (kg/m2) map will be overlayed with post-settlement deposition maps

  12. Throughfall-mediated alterations to soil microbial community structure in a forest plot of homogenous soil texture, litter, and plant species composition

    NASA Astrophysics Data System (ADS)

    Van Stan, John; Rosier, Carl; Moore, Leslie; Gay, Trent; Reichard, James; Wu, Tiehang; Kan, Jinjun

    2015-04-01

    Identifying spatiotemporal influences on soil microbial community (SMC) structure is critical to our understanding of patterns in biogeochemical cycling and related ecological services (e.g., plant community structure, water quality, response to environmental change). Since forest canopy structure alters the spatiotemporal patterning of precipitation water and solute supplies to soils (via "throughfall"), is it possible that changes in SMC structure could arise from modifications in canopy elements? Our study investigates this question by monitoring throughfall water and dissolved ion supply to soils beneath a continuum of canopy structure: from large gaps (0% cover), to bare Quercus virginiana Mill. (southern live oak) canopy (~50-70%), to heavy Tillandsia usneoides L. (Spanish moss) canopy (>90% cover). Throughfall water supply diminished with increasing canopy cover, yet increased washoff/leaching of Na+, Cl-, PO43-, and SO42- from the canopy to the soils. Presence of T. usneoides diminished throughfall NO3-, but enhanced NH4+, concentrations supplied to subcanopy soils. The mineral soil horizon (0-10 cm) sampled in triplicate from locations receiving throughfall water and solutes from canopy gaps, bare canopy, and T. usneoides-laden canopy significantly differed in soil chemistry parameters (pH, Ca2+, Mg2+, CEC). Polymerase Chain Reaction-Denaturant Gradient Gel Electrophoresis (PCR-DGGE) banding patterns beneath similar canopy covers (experiencing similar throughfall dynamics) also produced high similarities per ANalyses Of SIMilarity (ANO-SIM), and clustered together when analyzed by Nonmetric Multidimensional Scaling (NMDS). These results suggest that modifications of forest canopy structures are capable of affecting mineral-soil horizon SMC structure via throughfall when canopies' biomass distribution is highly heterogeneous. As SMC structure, in many instances, relates to functional diversity, we suggest that future research seek to identify functional

  13. Moisture and vegetation controls on decadal-scale accrual of soil organic carbon and total nitrogen in restored grasslands

    USGS Publications Warehouse

    O'Brien, S. L.; Jastrow, J.D.; Grimley, D.A.; Gonzalez-Meler, M. A.

    2010-01-01

    Revitalization of degraded landscapes may provide sinks for rising atmospheric CO2, especially in reconstructed prairies where substantial belowground productivity is coupled with large soil organic carbon (SOC) deficits after many decades of cultivation. The restoration process also provides opportunities to study the often-elusive factors that regulate soil processes. Although the precise mechanisms that govern the rate of SOC accrual are unclear, factors such as soil moisture or vegetation type may influence the net accrual rate by affecting the balance between organic matter inputs and decomposition. A resampling approach was used to assess the control that soil moisture and plant community type each exert on SOC and total nitrogen (TN) accumulation in restored grasslands. Five plots that varied in drainage were sampled at least four times over two decades to assess SOC, TN, and C4- and C3-derived C. We found that higher long-term soil moisture, characterized by low soil magnetic susceptibility, promoted SOC and TN accrual, with twice the SOC and three times the TN gain in seasonally saturated prairies compared with mesic prairies. Vegetation also influenced SOC and TN recovery, as accrual was faster in the prairies compared with C3-only grassland, and C4-derived C accrual correlated strongly to total SOC accrual but C3-C did not. High SOC accumulation at the surface (0-10 cm) combined with losses at depth (10-20 cm) suggested these soils are recovering the highly stratified profiles typical of remnant prairies. Our results suggest that local hydrology and plant community are critical drivers of SOC and TN recovery in restored grasslands. Because these factors and the way they affect SOC are susceptible to modification by climate change, we contend that predictions of the C-sequestration performance of restored grasslands must account for projected climatic changes on both soil moisture and the seasonal productivity of C4 and C3 plants. ?? 2009 Blackwell

  14. Is soil carbon storage underestimated?

    PubMed

    Díaz-Hernández, José Luis

    2010-06-01

    An accurate evaluation of the carbon stored in soils is essential to fully understand the role of soils as source or sink of atmospheric CO(2), as well as the feedback processes involved in soil-atmosphere CO(2) exchange. Depth and strategies of sampling have been, and still are, sources of uncertainties, because most current estimates of carbon storage in soils are based on conventional soil surveys and data sets compiled primarily for agricultural purposes. In a study of the Guadix-Baza basin, a semiarid area of southern Spain, sizeable amounts of carbon have been found stored in the subsoil. Total carbon estimated within 2-m was 141.3 kg Cm(-2) compared to 36.1 kg Cm(-2) if estimates were based solely on conventional soil depths (e.g. 40-cm in Regosols and 100-cm in Fluvisols). Thus, the insufficient sampling depth could lead to considerable underestimation of global soil carbon. In order to correctly evaluate the carbon content in world soils, more specific studies must be planned and carried out, especially in those soils where caliche and other carbonated cemented horizons are present.

  15. Spatial effects of aboveground biomass on soil ecological parameters and trace gas fluxes in a savannah ecosystem of Mount Kilimanjaro

    NASA Astrophysics Data System (ADS)

    Becker, Joscha; Gütlein, Adrian; Sierra Cornejo, Natalia; Kiese, Ralf; Hertel, Dietrich; Kuzyakov, Yakov

    2015-04-01

    The savannah biome is a hotspot for biodiversity and wildlife conservation in Africa and recently got in the focus of research on carbon sequestration. Savannah ecosystems are under strong pressure from climate and land-use change, especially around populous areas like the Mt. Kilimanjaro region. Savannah vegetation in this area consists of grassland with isolated trees and is therefore characterized by high spatial variation of canopy cover, aboveground biomass and root structure. Canopy structure is known to affect microclimate, throughfall and evapotranspiration and thereby controls soil moisture conditions. Consequently, the canopy structure is a major regulator for soil ecological parameters and soil-atmospheric trace gas exchange (CO2, N2O, CH4) in water limited environments. The spatial distribution of these parameters and the connection between above and belowground processes are important to understand and predict ecosystem changes and estimate its vulnerability. Our objective was to determine trends and changes of soil parameters and relate their spatial variability to the vegetation structure. We chose three trees from each of the two most dominant species (Acacia nilotica and Balanites aegyptiaca) in our research area. For each tree, we selected transects with nine sampling points of the same relative distances to the stem. Distances were calculated in relation to the crown radius. At these each sampling point a soil core was taken and separated in 0-10 cm and 10-30 cm depth. We measured soil carbon (C) and nitrogen (N) storage, microbial biomass carbon C and N, soil respiration as well as root biomass and -density, soil temperature and soil water content. Each tree was characterized by crown spread, leaf area index and basal area. Preliminary results show that C and N stocks decreased about 50% with depth independently of distance to the tree. Soil water content under the tree crown increased with depth while it decreased under grass cover. Microbial

  16. Soil and plant responses from land application of saline-sodic waters: Implications of management

    SciTech Connect

    Vance, G.F.; King, L.A.; Ganjegunte, G.K.

    2008-09-15

    Land application of co-produced waters from coalbed natural gas (CBNG) wells is one management option used in the Powder River Basin (PRB) of Wyoming and Montana. Unfortunately the co-produced CBNG waters may be saline and/or sodic. The objective of this study was to examine the effects of irrigation with CBNG waters on soils and plants in the PRB. Soil properties and vegetation responses resulting from 1 to 4 yr of saline sodic water (electrical conductivity (EC) 1.6-4.8 dS m{sup -1} sodium adsorption ratio (SAR), 17-57 mmol L- applications were studied during 2003 and 2004 field seasons on sites (Ustic Torriorthent Haplocambid, Haplargid and Paleargid) representing native range grasslands seeded grass hayfields and alfalfa hayfields. Parameters measured from each irrigated site were compared directly with representative non-irrigated sites. Soil chemical and physical parameters including pH, EC, SAR, exchangeable sodium percent, texture, bulk density, infiltration and Darcy flux rates, were measured at various depth intervals to 120 cm. Mulitple-year applications of saline sodic water produced consistent trends of increased soil EC AND SAR values to depths of 30 cm reduced surface infiltration rates and lowered Darcy flux rates to 120 cm. Significant differences (p {le} 0.05) were determined between irrigated and non-irrigated areas for EC, SAR infiltration rates and Darcy flux (p {le} 0.10) at most sites. Saline sodic CBNG water applications significantly increased native perennial grass biomass production and cover on irrigated as compared with non-irrigated sites; however overall species evenness decreased. Biological effects were variable and complex reflecting site-specific conditions and water and soil management strategies.

  17. Implications of inorganic fertilization of irrigated corn on soil properties: lessons learned after 50 years.

    PubMed

    Blanco-Canqui, Humberto; Schlegel, Alan J

    2013-01-01

    Inorganic fertilizers are widely used for crop production, but their long-term impacts on soil organic carbon (SOC) pools and soil physical attributes are not fully understood. We studied how half a century of N application at 0, 45, 90, 134, 179, and 224 kg ha and P application at 0, 20, and 40 kg ha (since 1992) affected SOC pools and soil structural and hydraulic parameters in irrigated continuous corn ( L.) under conventional till on an Aridic Haplustoll in the central Great Plains. Application of 45, 90, 134, 179, and 224 kg N ha increased the SOC pool by 4.6, 6.8, 7.6, 7.9, and 9.7 Mg ha, respectively, relative to nonfertilized plots in the 0- to 45-cm depth. Application of 20 kg P ha increased the SOC pool by 2.9 Mg ha in the 0- to 30-cm depth. The highest N rate increased the SOC pool by 195 kg ha yr. The C gains may be, however, offset by the C hidden costs of N fertilization. Application of >45 kg N ha reduced the proportion of soil macroaggregates (>0.25 mm) in the 7.5- to 30-cm depth. Fertilization did not affect hydraulic properties, but application of ≥90 kg N ha slightly increased aggregate water repellency. An increase in SOC concentration did not increase the mean weight diameter of wet aggregates ( = 0.1; > 0.10), but it slightly increased aggregate water repellency ( = 0.5; 0.005). Overall, long-term inorganic fertilization to irrigated corn can increase SOC pool, but it may reduce soil structural stability.

  18. Soil property effects on wind erosion of organic soils

    NASA Astrophysics Data System (ADS)

    Zobeck, Ted M.; Baddock, Matthew; Scott Van Pelt, R.; Tatarko, John; Acosta-Martinez, Veronica

    2013-09-01

    Histosols (also known as organic soils, mucks, or peats) are soils that are dominated by organic matter (OM > 20%) in half or more of the upper 80 cm. Forty two states have a total of 21 million ha of Histosols in the United States. These soils, when intensively cropped, are subject to wind erosion resulting in loss of crop productivity and degradation of soil, air, and water quality. Estimating wind erosion on Histosols has been determined by USDA-Natural Resources Conservation Service (NRCS) as a critical need for the Wind Erosion Prediction System (WEPS) model. WEPS has been developed to simulate wind erosion on agricultural land in the US, including soils with organic soil material surfaces. However, additional field measurements are needed to understand how soil properties vary among organic soils and to calibrate and validate estimates of wind erosion of organic soils using WEPS. Soil properties and sediment flux were measured in six soils with high organic contents located in Michigan and Florida, USA. Soil properties observed included organic matter content, particle density, dry mechanical stability, dry clod stability, wind erodible material, and geometric mean diameter of the surface aggregate distribution. A field portable wind tunnel was used to generate suspended sediment and dust from agricultural surfaces for soils ranging from 17% to 67% organic matter. The soils were tilled and rolled to provide a consolidated, friable surface. Dust emissions and saltation were measured using an isokinetic vertical slot sampler aspirated by a regulated suction source. Suspended dust was sampled using a Grimm optical particle size analyzer. Particle density of the saltation-sized material (>106 μm) was inversely related to OM content and varied from 2.41 g cm-3 for the soil with the lowest OM content to 1.61 g cm-3 for the soil with highest OM content. Wind erodible material and the geometric mean diameter of the surface soil were inversely related to dry clod

  19. 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.

  20. 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.

  1. Quantitative estimation of farmland soil loss by wind-erosion using improved particle-size distribution comparison method (IPSDC)

    NASA Astrophysics Data System (ADS)

    Rende, Wang; Zhongling, Guo; Chunping, Chang; Dengpan, Xiao; Hongjun, Jiang

    2015-12-01

    The rapid and accurate estimation of soil loss by wind erosion still remains challenge. This study presents an improved scheme for estimating the soil loss by wind erosion of farmland. The method estimates the soil loss by wind erosion based on a comparison of the relative contents of erodible and non-erodible particles between the surface and sub-surface layers of the farmland ploughed layer after wind erosion. It is based on the features that the soil particle-size distribution of the sampling soil layer (approximately 2 cm) is relatively uniform, and that on the surface layer, wind erosion causes the relative numbers of erodible and non-erodible particles to decrease and increase, respectively. Estimations were performed using this method for the wind erosion periods (WEP) from Oct. of 2012 to May of 2013 and from Oct. of 2013 to April of 2014 and a large wind-erosion event (WEE) on May 3, 2014 in the Bashang area of Hebei Province. The results showed that the average soil loss of farmland by wind erosion from Oct. of 2012 to May of 2013 was 2852.14 g/m2 with an average depth of 0.21 cm, while soil loss by wind from Oct. of 2013 to April of 2014 was 1199.17 g/m2 with a mean depth of 0.08 cm. During the severe WEE on May 3, 2014, the average soil loss of farmland by wind erosion was 1299.19 g/m2 with an average depth of 0.10 cm. The soil loss by wind erosion of ploughed and raked fields (PRF) was approximately twice as large as that of oat-stubble fields (OSF). The improved method of particle-size distribution comparison (IPSDC) has several advantages. It can not only calculate the wind erosion amount, but also the wind deposition amount. Slight changes in the sampling thickness and in the particle diameter range of the non-erodible particles will not obviously influence the results. Furthermore, the method is convenient, rapid, simple to implement. It is suitable for estimating the soil loss or deposition by wind erosion of farmland with flat surfaces and high

  2. [New index for soil moisture monitoring based on deltaT(s)-albedo spectral information].

    PubMed

    Yao, Yun-Jun; Qin, Qi-Ming; Zhao, Shao-Hua; Shen, Xin-Yi; Sui, Xin-Xin

    2011-06-01

    Monitoring soil moisture by remote sensing has been an important problem for both agricultural drought monitoring and water resources management. In the present paper, we acquire the land surface temperature difference (deltaT(s)) and broadband albedo using MODIS Terra reflectance and land surface temperature products to construct the deltaT(s)-albedo spectral feature space. According to the soil moisture variation in spectral feature space, we put forward a simple and practical temperature difference albedo drought index (TDADI) and validate it using ground-measured 0-10 cm averaged soil moisture of Ningxia plain The results show that the coefficient of determination (R2) of both them varies from 0.36 to 0.52, and TDADI has higher accuracy than temperature albedo drought index (TADI) for soil moisture retrieval. The good agreement of TDADI, Albedo/LST, LST/ NDVI and TVDI for analyzing the trends of soil moisture change supports the reliability of TDADI. However, TDADI has been designed only at Ningxia plain and still needs further validation in other regions.

  3. Increasing temperature reduces the coupling between available nitrogen and phosphorus in soils of Chinese grasslands.

    PubMed

    Geng, Yan; Baumann, Frank; Song, Chao; Zhang, Mi; Shi, Yue; Kühn, Peter; Scholten, Thomas; He, Jin-Sheng

    2017-03-07

    Changes in climatic conditions along geographical gradients greatly affect soil nutrient cycling processes. Yet how climate regimes such as changes in temperature influence soil nitrogen (N) and phosphorus (P) concentrations and their stoichiometry is not well understood. This study investigated the spatial pattern and variability of soil N and P availability as well as their coupling relationships at two soil layers (0-10 and 10-20 cm) along a 4000-km climate transect in two grassland biomes of China, the Inner Mongolian temperate grasslands and the Tibetan alpine grasslands. Our results found that in both grasslands, from cold to warm sites the amounts of soil total N, total P and available P all decreased. By contrast, the amount of available N was positively related to mean annual temperature in the Tibetan grasslands. Meanwhile, with increasing temperature ratio of available N to P significantly increased but the linear relationship between them was considerably reduced. Thus, increasing temperature may not only induce a stoichiometric shift but also loose the coupling between available N and P. This N-P decoupling under warmer conditions was more evident in the Tibetan alpine grasslands where P limitation might become more widespread relative to N as temperatures continue to rise.

  4. Effects of electron irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    One OHM-cm and 10 OHM-cm silicon solar cells were exposed to 1.0 MeV electrons at a fixed flux of 10 to the 11th power e/sq cm/sec and fluences of 10 to the 13th power, 10 to the 14th power and 10 to the 15th power e/sq.cm. 1-V curves of the cells were made at room temperature, - 63 C and + or - 143 C after each irradiation. A value of 139.5 mw/sq cm was used as AMO incident energy rate per unit area. The 10 OHM-cm cells appear more efficient than 1 OHM-cm cells after exposure to a fluence greater than 10 to the 14th power e/sq cm. The 1.0 MeV electron damage coefficients for both 1 OHM-cm and 10 OHM-cm cells are somewhat less than those for previously irradiated cells at room temperature. The values of the damage coefficients increase as the cell temperatures decrease. Efficiencies pertaining to maximum power output are about the same as those of n on p silicon cells evaluated previously.

  5. Abundance and stratification of soil macroarthropods in a Caatinga Forest in Northeast Brazil.

    PubMed

    Araújo, V F P; Bandeira, A G; Vasconcellos, A

    2010-10-01

    In arid and semiarid environments, seasonality usually exerts a strong influence on the composition and dynamics of the soil community. The soil macroarthropods were studied in a Caatinga forest located in the Reserva Particular do Patrimônio Natural (RPPN) Fazenda Almas, São José dos Cordeiros, Paraíba, Brazil. Samples were collected during the dry and rainy seasons following the method proposed by the Tropical Soil Biology and Fertility Program (TSBF), with minor modifications. At each station, 15 soil blocks (20 × 20 × 30 cm: 12 L) were extracted and divided into three layers: A (0-10 cm), B (10-20 cm), and C (20-30 cm). In the rainy and dry seasons 1,306 ± 543(se) and 458 ± 212 ind.m-2 macroarthropods were found, respectively, with 35 and 18 respective taxa recorded. The abundance of individuals and taxa were significantly higher in the rainy season. Isoptera (57.8%) was the most abundant taxon, followed by Hymenoptera: Formicidae (17.2%), Coleoptera larvae (7.3%), and Araneae (3.5%). In the rainy season, abundance in layer A (576 ± 138 ind.m-2) was significantly higher than that of layer C (117 ± 64 ind.m-2), but was not different from layer B (613 ± 480 ind.m-2). There was also no difference between the layer B and C abundances. In the dry season, abundance in layer B (232 ± 120 ind.m-2) was not significantly different compared to layer A (182 ± 129 ind.m-2), but was significantly higher than abundance in layer C (44 ± 35 ind.m-2). During the rainy season, layer A (34 taxa) was significantly richer in taxa than layers B (19 taxa) and C (11 taxa). On the other hand, during the dry season the richness of layers A (12 taxa) and B (12 taxa) was equal, but significantly higher than that of layer C (6 taxa). Richness of taxa and abundance were positively correlated with soil organic matter and negatively correlated with soil temperature. The community of soil macroarthropods in the area of Caatinga studied has taxonomic and functional structures that

  6. Long-term variation in above and belowground plant inputs alters soil organic matter biogeochemistry at the molecular-level

    NASA Astrophysics Data System (ADS)

    Simpson, M. J.; Pisani, O.; Lin, L.; Lun, O.; Simpson, A.; Lajtha, K.; Nadelhoffer, K. J.

    2015-12-01

    The long-term fate of soil carbon reserves with global environmental change remains uncertain. Shifts in moisture, altered nutrient cycles, species composition, or rising temperatures may alter the proportions of above and belowground biomass entering soil. However, it is unclear how long-term changes in plant inputs may alter the composition of soil organic matter (SOM) and soil carbon storage. Advanced molecular techniques were used to assess SOM composition in mineral soil horizons (0-10 cm) after 20 years of Detrital Input and Removal Treatment (DIRT) at the Harvard Forest. SOM biomarkers (solvent extraction, base hydrolysis and cupric (II) oxide oxidation) and both solid-state and solution-state nuclear magnetic resonance (NMR) spectroscopy were used to identify changes in SOM composition and stage of degradation. Microbial activity and community composition were assessed using phospholipid fatty acid (PLFA) analysis. Doubling aboveground litter inputs decreased soil carbon content, increased the degradation of labile SOM and enhanced the sequestration of aliphatic compounds in soil. The exclusion of belowground inputs (No roots and No inputs) resulted in a decrease in root-derived components and enhanced the degradation of leaf-derived aliphatic structures (cutin). Cutin-derived SOM has been hypothesized to be recalcitrant but our results show that even this complex biopolymer is susceptible to degradation when inputs entering soil are altered. The PLFA data indicate that changes in soil microbial community structure favored the accelerated processing of specific SOM components with littler manipulation. These results collectively reveal that the quantity and quality of plant litter inputs alters the molecular-level composition of SOM and in some cases, enhances the degradation of recalcitrant SOM. Our study also suggests that increased litterfall is unlikely to enhance soil carbon storage over the long-term in temperate forests.

  7. Soil-vegetation relationships on a banded ironstone 'island', Carajás Plateau, Brazilian Eastern Amazonia.

    PubMed

    Nunes, Jaquelina A; Schaefer, Carlos E G R; Ferreira Júnior, Walnir G; Neri, Andreza V; Correa, Guilherme R; Enright, Neal J

    2015-01-01

    Vegetation and soil properties of an iron-rich canga (laterite) island on the largest outcrop of banded-iron formation in Serra de Carajás (eastern Amazonia, Brazil) were studied along a topographic gradient (738-762 m asl), and analyzed to test the hypothesis that soil chemical and physical attributes play a key role in the structure and floristic composition of these plant communities. Soil and vegetation were sampled in eight replicate plots within each of the four vegetation types. Surface (0-10 cm) soil samples from each plot were analyzed for basic cations, N, P and plant species density for all species was recorded. CCA ordination analysis showed a strong separation between forest and non-forest sites on the first axis, and between herbaceous and shrubby campo rupestre on the second axis. The four vegetation types shared few plant species, which was attributed to their distinctive soil environments and filtering of their constituent species by chemical, physical and hydrological constraints. Thus, we can infer that Edaphic (pedological) factors are crucial in explaining the types and distributions of campo rupestre vegetation associated with ferruginous ironstone uplands (Canga) in Carajás, eastern Amazonia, therefore the soil properties are the main drivers of vegetation composition and structure on these ironstone islands.

  8. The early stage of soil formation and weathering of mantle loam components under impact of forest and meadow communities

    NASA Astrophysics Data System (ADS)

    Chizhikova, Nataliya; Verkhovets, Irina

    2013-04-01

    Mineralogical composition of clay fraction from the less developed soils of the model large lysimeters have been studied after 30-year period of soil formation. The parent material for experiment is mantle non-calcareous silty clay loams that are widespread in the center of the Russian Plain. X-ray diffraction and term gravimetric methods for determination clay minerals and organic matter are used. The mineralogical composition of clay fraction sampled from mantle loams is represented the paragenetic association of follow minerals: smectite phase (40-60%), hydromicas (30-50%), kaolinite, chlorite (sum 7-16%) and traces of clay-sized quartz. The smectite phase consist of complex irregular interstratified mica-smectite with high and low contents of the smectite layers, chlorite-smectite with different ratios between chlorite and smectite layers, chlorite-vermiculite and individual smectites. The hydromicas comprises tri- and dioctahedral subgroups. At the early stage of soil formation during 30-year period, the accumulation of humus and the weakly pronounced eluvial-illuvial redistribution of clay fraction appears in the upper 0-10 cm layer. There is a trend of partially destruction of smectite phase, and relative accumulation of hydromicas and kaolinite in the upper layer. Intensity of soil profile differentiation depends on plant community. Spruce stands produce acid reaction of soil solution, therefore podzolic process starts. Mixed oak and maple stands don't change reaction of soil solution and promote the depletion of smectite phase from the upper horizons due to lessivage.

  9. 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.

  10. Landslide-induced changes in soil phosphorus speciation and availability in Xitou, Central Taiwan

    NASA Astrophysics Data System (ADS)

    Cheng, Chih-Hsin; Hsiao, Sheng-Che; Huang, Yu-Sheng; Chen, Chiu-Ping; Menyailo, Oleg

    2016-04-01

    Phosphorus is an important nutrient in forest ecosystem. In tropical/subtropical areas, phosphorus is generally limited because of strong soil weathering but its speciation and availability can be changed by disturbances, such as the geological landslide events. In this study, we evaluated the changes in soil P speciation and availability after landslide in a mountainous forest ecosystem in Xitou, central Taiwan. Five soil pedons along a landslide/nonlanslide affected sequence from deep landslide deposit to nonlandslide were collected. The Hedley's sequential extraction procedure and synchrotron-based phosphorus x-ray adsorption near edge structure (XANES) spectroscopy were applied for the surface 0-10 cm and 10-20 cm soils to provide information concerning chemical and structural composition of phosphorus. The results indicated that plant available P (Resin-P + NaHCO3 extract P) and total P were reduced after landslide, from 150 and 500 mg kg-1, respectively, at nonlandsliding sites to 50 and 350 mg kg-1 at landsliding sites. However, the apatite-type P was significantly increased after landslide, from about 70 mg kg-1 at nonlandsliding sites to around 200 mg kg-1 at landsliding sites. Similar trend of enhanced apatite-type P after landslide was also observed in the XANES spectra. The ryegrass pot experiment confirmed that the landsliding soils were less fertile and had less growth rate. However, both nitrogen and phosphorus nutrients were limited at landsliding sites. The results demonstrated that soil P speciation and availability were significantly altered after landslide; these resultant changes are expected to influence functions in forest ecosystems.

  11. 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.

  12. Effects of proton irradiation and temperature on 1 ohm-cm and 10 ohm-cm silicon solar cells

    NASA Technical Reports Server (NTRS)

    Nicoletta, C. A.

    1973-01-01

    The 1 ohm-cm and 10 ohm-cm silicon solar cells were exposed to 1.0 MeV protons at a fixed flux of 10 to the 9th power P/sq cm-sec and fluences of 10 to the 10th power, 10 to the 11th power, 10 to the 12th power and 3 X 10 to the 12th power P/sq cm. I-V curves of the cells were made at room temperature, 65 C and 165 C after each irradiation. A value of 139.5 mw/sq cm was taken as AMO incident energy rate per unit area. Degradation occurred for both uncovered 1 ohm-cm and 10 ohm-cm cells. Efficiencies are generally higher than those of comparable U.S. cells tested earlier. Damage (loss in maximum power efficiency) with proton fluence is somewhat higher for 10 ohm-cm cells, measured at the three temperatures, for fluences above 2 X 10 to the 11th power P/sq cm. Cell efficiency, as expected, changes drastically with temperature.

  13. Fast neutron induced fission cross sections of {sup 242m}Am, {sup 245}Cm, {sup 247}Cm

    SciTech Connect

    Fursov, B.I.; Samylin, B.F.; Smirenkin, G.N.; Polynov, V.N.

    1994-12-31

    The experimental data on {sup 242m}Am, {sup 245}Cm and {sup 247}Cm fission cross sections in the 0.13-7.2 Mev neutron energy range are presented. The measurements were made at Van-de-Graaf accelerators with monoenergetic neutron sources. The total data errors are 3.8% for {sup 242m}Am, 3.5% for {sup 245}Cm and 4.5% for {sup 247}Cm. The results given in this paper are preliminary ones.

  14. Development of ferroelectric correlations in the quantum paraelectric and antiferrodistortive regimes in BaxSr1-xTiO3 (x ≤ 0.10)

    NASA Astrophysics Data System (ADS)

    Hassnain Jaffari, G.; Mehmood, Zahid; Iqbal, Asad M.; Hasanain, S. K.; Ismat Shah, S.

    2014-08-01

    The dielectric response ɛ ( T ) of BaxSr1-xTiO3 (x ≤ 0.1) for compositions at and below the critical composition for the ferroelectric transition has been studied. With progressive Ba substitution, the growth of ferroelectric correlations and the weakening of the Antiferrodistortive (AFD) and the quantum paraelectric (QPE) effects have been studied by monitoring the changes in both the in and out of phase parts of the dielectric response. For the compositions close to pure SrTiO3 (x = 0 and x = 0.02), the temperature dependence exhibits a continuous rise in the in-phase part and no ferroelectric peak, consistent with the QPE behavior. With increasing Ba substitution, the low temperature behavior of the in phase part ɛ ' progressively changes from a continuous rise to exhibit a weak maximum and finally to a well developed cusp. For higher Ba concentrations, the low temperature peak (T ˜ 50K), which corresponds to ferroelectric correlations, becomes increasingly sharper until at the critical composition, x = 0.10, the system shows a single well defined ferroelectric peak. However, the out of phase response of the x = 0.1 composition exhibited a succession of three BaTiO3 type ferroelectric transitions. For x ≤ 0.04, the out of phase part shows evidence of an ordering around T ˜ 100K, which is the expected AFD ordering temperature. The deviations of the ɛ ' ( T ) data from the Curie-Weiss law have been analyzed within the frame work of two different theoretical models. It was determined that the dielectric behavior for lower concentrations of Ba (up to x ≤ 0.08) was explainable in terms of a model of non-interacting regions which are themselves homogeneously polarized and undergo a second order phase transition. For the phase boundary composition, i.e., x = 0.1, on the other hand, the data are explainable in terms of the Sherrington and Kirkpatrick model which includes the effects of weak correlations between the polar regions characterized by a glassy

  15. Heavy metal concentrations in soils and vegetation in urban areas of Quezon City, Philippines.

    PubMed

    Navarrete, Ian A; Gabiana, Christella C; Dumo, Joan Ruby E; Salmo, Severino G; Guzman, Maria Aileen Leah G; Valera, Nestor S; Espiritu, Emilyn Q

    2017-04-01

    Limited data have been published on the chemistry of urban soils and vegetation in the Philippines. The aim of this study is to quantify the concentrations of heavy metals (i.e., Cr, Ni, Cu, Zn, and Pb) in soils and vegetation in the urban landscape of Quezon City, Philippines, and to elucidate the relationships between soil properties and the concentration of heavy metals pertaining to different land uses [i.e., protected forest (LM), park and wildlife area (PA), landfill (PL), urban poor residential and industrial areas (RA), and commercial areas (CA)]. Soil (0-15 cm) and senescent plant leaves were collected and were analyzed for soil properties and heavy metal concentrations. Results revealed that the concentrations of heavy metals (i.e., Cr, Ni, Cu, Zn, and Pb) in urban soils were higher in areas where anthropogenic activities or disturbance (PL, RA, and CA) were dominant as compared to the less disturbed areas (LM and PA). Organic matter and available phosphorous were strongly correlated with heavy metal concentrations, suggesting that heavy metal concentrations were primarily controlled by these soil properties. The average foliar heavy metal concentrations varied, ranging from 0 to 0.4 mg/kg for Cd, 0-10 mg/kg for Cr, 2-22 mg/kg for Cu, 0-5 mg/kg for Pb, and 11-250 mg/kg for Zn. The concentrations of Cd and Cr exceeded the critical threshold concentrations in some plants. Leaves of plants growing in PL (i.e., landfill) showed the highest levels of heavy metal contamination. Our results revealed that anthropogenic activities and disturbance caused by the rapid urbanization of the city are major contributors to the heavy metal accumulation and persistence in the soils in these areas.

  16. Characterizing Soil Organic Carbon Recalcitrance in Longleaf Pine (Pinus palustris Mill) Stands

    NASA Astrophysics Data System (ADS)

    Butnor, J. R.; Samuelson, L. J.; Anderson, P. H.; Gonzalez-Benecke, C. A.; Boot, C. M.; Cotrufo, M. F.; Heckman, K. A.; Jackson, J. A.; Johnsen, K. H.; Stokes, T.; Swanston, C.

    2015-12-01

    Historically, longleaf pine (LLP) stands in the southeastern US experienced frequent fires. Today managed LLP stands are burned at 2-5 year intervals to reduce fuels and hardwood competition and manage for biodiversity. These are not stand replacing fires, though considerable amounts of biomass are burned and the conversion rate to biochemically stabilized black carbon (BC) is unknown. The primary mechanisms for long-term carbon sequestration in soil are mineral association, biochemical transformation (e.g. pyrogenesis) and physical protection. We quantified the recalcitrance of soil organic carbon (SOC) and its oxidation resistant fraction (SOCR; defined as residual SOC following H2O2 treatment and dilute HNO3 digestion) using radiocarbon dating (SOC and SOCR) and benzene polycarboxylic acids (BPCA) as molecular markers for polyaromatic C associated with BC. Mineral stabilized C is largely represented by SOCR contents and BC by total BPCA contents. Soils were collected by depth (0-10, 10-20, 20-50, 50-100 cm) at 14 managed LLP stands in Louisiana (LA), Georgia (GA) and North Carolina (NC) burned every two to five years. Across all sites, SOC and SOCR contents declined with soil depth, though SOCR:SOC increased with depth (0.13, 0.15, 0.22, 0.31). SOCR was more 14C depleted than SOC and Δ14C values became more negative with soil depth (SOCR: -195, -318, -458, -553 vs. SOC 23, -39, -156, -334), indicating that SOCR had a much longer mean residence time. The Δ14C values correspond to mean ages of SOCR ranging from 1777 to 6969 years and of SOC from 84 to 3319 years. We obtained very low BPCA yield from SOCR, and it is unclear whether BC was absent or not accessible with the BPCA method. Preliminary analysis of total BPCA (bulk soil) indicates interactions between soil series and depth. Total BPCA concentration of SOC in the upper 10 cm was 136 g kg-1 C in LA and more than six times the concentration in GA and NC. On deep sands in NC, the highest BPCA concentration

  17. 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...

  18. Room temperature long range ferromagnetic ordering in Ni{sub 0.58}Zn{sub 0.42}Co{sub 0.10}Cu{sub 0.10}Fe{sub 1.8}O{sub 4} nano magnetic system

    SciTech Connect

    Sarveena, Chand, Jagdish; Verma, S.; Singh, M.; Kotnala, R. K.; Batoo, K. M.

    2015-06-24

    The structural and magnetic behavior of sol-gel autocombustion synthesized nanocrystalline Ni{sub 0.58}Zn{sub 0.42}Co{sub 0.10}Cu{sub 0.10}Fe{sub 1.8}O{sub 4} have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy and vibrating sample magnetometer(VSM). Sample of high purity and high homogeneity was obtained by calcination at low temperature (500°C) resulting in nanoparticles of average diameter ∼15nm as determined by XRD and further confirmed by TEM. X-ray diffraction (XRD) and selective area diffraction (SAED) confirmed the single phase of the sample. Mössbauer results are supported by magnetization data. Well defined sextets and appearance of hysteresis at room temperature indicate the existence of ferromagnetic coupling at room temperature finding material utility in magnetic storage data. The existence of iron in ferric state confirmed by isomer shift is a clear evidence of improved magnetic properties of the present system.

  19. Physical and chemical properties of young soils of the Icelandic highlands

    NASA Astrophysics Data System (ADS)

    Gísladóttir, Guðrún; Mankasingh, Utra

    2015-04-01

    Most of the Icelandic soils are of volcanic origin, classified as andisols (carbon content 1-12%), many of which are strongly affected by erosion and so, formation of new soils is of great interest. The effect of land cover type on the weathering patterns and the formation of new soils are of interest. The southern Icelandic highlands are characterised by harsh climate, shallow soils and limited vegetation cover. We hypothesise that in the highland regions of Iceland the progression of land cover from unvegetated to vegetated sites will impact soil development. This study describes the physical and chemical properties of highland soils in Iceland. Soil samples were collected from 12 sites in September 2013, nine sites were fully vegetated and three unvegetated: grassland (G1-G8), with moss, Carex Bigelowii and dwarf shrubs, sandy fluvial wetland (S) and unvegetated gravels (M1-M3). All soils with vegetative cover were characterized by weak or structureless soil ranging in texture from loamy sand to silty clay loam, while at unvegetated sites soil texture was structureless and sandy. On average, the bulk density of soils (range 0.53 - 1.16 g cm-3) were lower at vegetated sites than unvegetated sites. The soil depth is greater in the vegetated sites, indicating greater soil development. The average % carbon (%C), % nitrogen (%N), overall % soil organic matter (%SOM), of vegetated sites were higher than for unvegetated sites, indicating the difference in soil development: vegetated sites (mean), 1.60%C, 0.10%N, 4.9%SOM; unvegetated sites (mean), 0.27%C, 0.02%N, 1.81%SOM. All soils had significant amounts of amorphous clay minerals such as allophone, imogolite, ferrihydrite or aluminium-humus complexes and also high aluminium and iron percentages, and high phosphate retention. All of which are characteristic for andisols. There were strong associations between Fe and Al and the soil C, which are indicative of Al and Fe complexed with humus or allophane and ferrihydrite

  20. 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.

  1. Prediction of soil organic carbon concentration and soil bulk density of mineral soils for soil organic carbon stock estimation

    NASA Astrophysics Data System (ADS)

    Putku, Elsa; Astover, Alar; Ritz, Christian

    2016-04-01

    Soil monitoring networks provide a powerful base for estimating and predicting nation's soil status in many aspects. The datasets of soil monitoring are often hierarchically structured demanding sophisticated data analyzing methods. The National Soil Monitoring of Estonia was based on a hierarchical data sampling scheme as each of the monitoring site was divided into four transects with 10 sampling points on each transect. We hypothesized that the hierarchical structure in Estonian Soil Monitoring network data requires a multi-level mixed model approach to achieve good prediction accuracy of soil properties. We used this database to predict soil bulk density and soil organic carbon concentration of mineral soils in arable land using different statistical methods: median approach, linear regression and mixed model; additionally, random forests for SOC concentration. We compared the prediction results and selected the model with the best prediction accuracy to estimate soil organic carbon stock. The mixed model approach achieved the best prediction accuracy in both soil organic carbon (RMSE 0.22%) and bulk density (RMSE 0.09 g cm-3) prediction. Other considered methods under- or overestimated higher and lower values of soil parameters. Thus, using these predictions we calculated the soil organic carbon stock of mineral arable soils and applied the model to a specific case of Tartu County in Estonia. Average estimated SOC stock of Tartu County is 54.8 t C ha-1 and total topsoil SOC stock 1.8 Tg in humus horizon.

  2. Assessing the Utility of 3-km Land Information System Soil Moisture Data for Drought Monitoring and Hydrologic Applications

    NASA Technical Reports Server (NTRS)

    White, Kristopher D.; Case, Jonathan L.

    2014-01-01

    The NASA Short term Prediction Research and Transition (SPoRT) Center in Huntsville, AL has been running a real-time configuration of the Noah land surface model within the NASA Land Information System (LIS) since June 2010. The SPoRT LIS version is run as a stand-alone land surface model over a Southeast Continental U.S. domain with 3-km grid spacing. The LIS contains output variables including soil moisture and temperature at various depths, skin temperature, surface heat fluxes, storm surface runoff, and green vegetation fraction (GVF). The GVF represents another real-time SPoRT product, which is derived from the Moderate Resolution Imaging Spectroradiometer instrument aboard NASA's Aqua and Terra satellites. These data have demonstrated operational utility for drought monitoring and hydrologic applications at the National Weather Service (NWS) office in Huntsville, AL since early 2011. The most relevant data for these applications have proven to be the moisture availability (%) in the 0-10 cm and 0-200 cm layers, and the volumetric soil moisture (%) in the 0-10 cm layer. In an effort to better understand their applicability among locations with different terrain, soil and vegetation types, SPoRT is conducting the first formal assessment of these data at NWS offices in Houston, TX, Huntsville, AL and Raleigh, NC during summer 2014. The goal of this assessment is to evaluate the LIS output in the context of assessing flood risk and determining drought designations for the U.S. Drought Monitor. Forecasters will provide formal feedback via a survey question web portal, in addition to the NASA SPoRT blog. In this presentation, the SPoRT LIS and its applications at NWS offices will be presented, along with information about the summer assessment, including training module development and preliminary results.

  3. Visualizing the Stability of Char: Molecular- to Micron-scale Observations of Char Incubated in a Tropical Soil

    NASA Astrophysics Data System (ADS)

    Heckman, K. A.; Ramon, C.; Weber, P. K.; Torn, M. S.; Pett-Ridge, J.; Nico, P. S.

    2014-12-01

    The persistence of pyrogenic materials (hereafter referred to as char) in terrestrial ecosystems is of interest both from a carbon cycle modelling perspective and a climate change mitigation standpoint. However, the fate of newly introduced char in soils remains unclear. Recent reviews attempting to summarize trends in char decomposition have come to differing conclusions, further stressing the complexity of factors dictating char stability in soils. The current dataset specifically addresses the stability of char additions to a tropical clay-rich soil, possible priming effects, and interactions among char, microbial communities and the mineral matrix. 13C- and 15N-labeled Acer rubrum(red maple) wood was combusted at 400°C and added to surface (0-10 cm) and subsurface (20-30 cm) soils from the Luquillo Experimental Forest, Puerto Rico. Soils were incubated for 13 and 345 days at 26°C. Following incubation, intact microaggregates were frozen and cryosectioned into thin sections of approximately 5 μm thickness and mounted on gold-coated quartz slides. Thin sections were examined by synchrotron-based Fourier transform infrared spectroscopy (SR-FTIR), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and high resolution secondary ion mass spectrometry (nanoSIMS). The combination of these μm to nm scale techniques allowed us to create corresponding spatial maps of native organic matter, char, and mineral phase distribution, track spatial variability in organic matter molecular structure, and dispersion of 13C and 15N isotopic labels. We present preliminary results indicating a high degree of stability of char in these wet tropical soils throughout the incubation period, suggesting that applied char may persist for long periods of time in similar soils.

  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. Alteration and formation of rims on the CM parent body

    NASA Astrophysics Data System (ADS)

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

    1994-03-01

    All types of coarse-grained components in CM chondrites are surrounded by fine-grained dust coatings, but the origin of these rims is not yet clear. Although a strictly nebular origin seems likely for rims in the relatively unaltered type 3 chondrites, the rims in CM chondrites are dominated by secondary alteration phases. It has been argued that either the coarse-grained cores accreted altered rim materials while still in the nebula or that alteration of primary rim phases occurred on the CM parent body. To constrain the origin of alteration phases in rim material, we have analyzed the textures and mineral associations from 10 CM chondritic falls by optical and scanning electron microscopy. Our results indicate that the secondary phases in CM chondritic rims were produced by parent body fluid-rock interactions which redefined some primary rim textures and may have produced, in some cases, both coarse-grained components and the rims that surround them. Textural features demonstrate the interactive exchange of alteration fluids between rims, matrix, and chondrules on the CM parent body. For example, most matrix-rim contacts are gradational, suggesting the synchronous alteration of both components. Several observations suggest the possibility of in situ rim production. For example, tochilinite and phyllosilicates commonly form rims around matrix carbonates, which are generally believed to have precipitated from alteration fluids on the CM parent body. This suggests that the rims surrounding matrix carbonates may also have been produced by alteration processes. Partially replaced chondrule olivines bear a striking resemblance to many rimmed olivines in the matrix which suggests, by analogy, that site-specific precipitation of S-bearing phases may also be responsible for the occurrence of many tochilinite-rich rims around isolated matrix olivines. Non-silicate rims precipitate around olivines of any composition, but the process is most effective for fayalitic olivines

  7. 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

  8. 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…

  9. 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.…

  10. Changes in soil phosphorus fractions following woody plant invasion of grassland

    NASA Astrophysics Data System (ADS)

    Kantola, I. B.; Boutton, T. W.; Filley, T. R.; Hallmark, C. T.

    2010-12-01

    Many grass-dominated ecosystems around the world have experienced woody plant encroachment over the last century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands and altered the biogeochemistry of this region. The purpose of this study was to assess the impact of this grassland-to-woodland transition on the size, distribution, and availability of soil P pools. A modified Hedley method was employed to fractionate soil P into pools based on organic and inorganic forms and relative plant-availability. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 14 to 86 years in a subtropical savanna parkland in southern Texas. Soil P was fractionated into resin-extractable inorganic P, bicarbonate-extractable organic and inorganic P, hydroxide-extractable organic and inorganic P, acid-extractable inorganic P, and residual inorganic P forms. P concentrations in these fractions were determined by colorimetry, and soil total P was determined by lithium fusion. Organic P was calculated from the difference between total and inorganic P. Total P in whole soils increased dramatically from 102 mg P/kg soil in remnant grasslands to 166 mg P/kg soil in the oldest woody plant stands (70-85 years). P concentrations in all pools increased linearly with increasing woody plant stand age except acid-extractable phosphorus. The most dramatic increases were observed in the resin-extractable fraction (plant-available P), which increased from 3 to 13 mg P/kg soil, and in hydroxide-extractable P (the majority of the organic P in the system), which increased from 15 mg P/kg soil in grasslands to 26 mg P/kg soil in the wooded clusters. Although the exact mechanisms by which soil P increases following woody invasion remain unknown, we suggest that the

  11. Changes in Soil Phosphorus Fractions Following Woody Plant Invasion of Grassland

    NASA Astrophysics Data System (ADS)

    Boutton, T. W.; Kantola, I. B.; Filley, T. R.

    2012-12-01

    Many grass-dominated ecosystems around the world have experienced woody plant encroachment over the last century due to livestock grazing, fire suppression, and/or changes in climate and atmospheric chemistry. In the Rio Grande Plains of Texas, subtropical thorn woodlands dominated by N-fixing tree legumes have largely replaced grasslands and altered the biogeochemistry of this region. The purpose of this study was to assess the impact of this grassland-to-woodland transition on the size, distribution, and availability of soil P pools. A modified Hedley method was employed to fractionate soil P into pools based on organic and inorganic forms and relative plant-availability. Soil samples (0-10 cm) were collected in remnant grasslands and near the centers of woody plant clusters ranging in age from 14 to 86 yrs in a subtropical savanna parkland in southern Texas. Soil P was fractionated into resin-extractable inorganic P, bicarbonate-extractable organic and inorganic P, hydroxide-extractable organic and inorganic P, acid-extractable inorganic P, and residual inorganic P forms. P concentrations in these fractions were determined by colorimetry, and soil total P was determined by lithium fusion. Organic P was calculated from the difference between total and inorganic P. Total P in whole soils increased dramatically from 98 mg P kg-1 soil in remnant grasslands to 168 mg P kg-1 soil in the oldest woody plant stands (70-85 yrs). P concentrations in all pools increased linearly with increasing woody plant stand age except acid-extractable phosphorus. The most dramatic increases were observed in the resin-extractable fraction (plant-available P), which increased from 3 to 13 mg P kg-1 soil, and in hydroxide-extractable P (the majority of the organic P in the system), which increased from 15 mg P kg-1 soil in grasslands to 26 mg P kg-1 soil in the wooded clusters. Although the exact mechanisms by which soil P increases following woody invasion remain unknown, we suggest that

  12. The Bio-accessibility of Synthetic Fe-Organo Complexes in Subsurface Soil with Elevated Temperature: a Proxy for the Vulnerability of Mineral Associated Carbon to Warming Rachel C. Porras, Peter S. Nico, and Margaret Torn Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA

    NASA Astrophysics Data System (ADS)

    Porras, R. C.; Hicks Pries, C.

    2015-12-01

    Globally, subsurface soils (>30 cm) represent an important reservoir of soil organic carbon (SOC). However, the vulnerability of this deep SOC and, in particular mineral-associated SOC, to warming, and its potential to amplify the effects of climate change is highly uncertain. To gain insight into the bio-accessibility and temperature sensitivity of mineral-associated organic C, we conducted a series of incubations using soils collected from three depths (0-10, 50-60, and 80-90 cm) under coniferous forest. The soils are moderately acidic (mean pH=6.5) sandy, mixed, mesic Ultic Haploxeralfs. To understand how mechanisms controlling SOC bio-accessibilty or temperature sensitivity differ with depth and with the properties of Fe-organo complexes (i.e.,degree of crystallinity, amount of reactive surface area, or surface saturation), we used a 13C labeled glucose substrate to prepare synthetic Fe-organo complexes spanning a range of crystallinity and mineral surface saturation. The synthetic Fe-organo complexes were then added to soil from three depths. The soils containing the 13C labeled Fe-organo adduct were incubated at two temperatures (ambient and +4°C) and respired 13CO2 was measured and used to estimate flux rates. Differences in measured 13CO2 fluxes as a function of depth, surface loading, and mineral properties are discussed in terms of their implications for the temperature sensitivity of mineral protected organic carbon in subsurface soils.

  13. 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.

  14. The 21-cm Signal from the cosmological epoch of recombination

    SciTech Connect

    Fialkov, A.; Loeb, A. E-mail: aloeb@cfa.harvard.edu

    2013-11-01

    The redshifted 21-cm emission by neutral hydrogen offers a unique tool for mapping structure formation in the early universe in three dimensions. Here we provide the first detailed calculation of the 21-cm emission signal during and after the epoch of hydrogen recombination in the redshift range of z ∼ 500–1,100, corresponding to observed wavelengths of 100–230 meters. The 21-cm line deviates from thermal equilibrium with the cosmic microwave background (CMB) due to the excess Lyα radiation from hydrogen and helium recombinations. The resulting 21-cm signal reaches a brightness temperature of a milli-Kelvin, orders of magnitude larger than previously estimated. Its detection by a future lunar or space-based observatory could improve dramatically the statistical constraints on the cosmological initial conditions compared to existing two-dimensional maps of the CMB anisotropies.

  15. CM Process Improvement and the International Space Station Program (ISSP)

    NASA Technical Reports Server (NTRS)

    Stephenson, Ginny

    2007-01-01

    This viewgraph presentation reviews the Configuration Management (CM) process improvements planned and undertaken for the International Space Station Program (ISSP). It reviews the 2004 findings and recommendations and the progress towards their implementation.

  16. 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.

  17. Soils and the soil cover of the Valley of Geysers

    NASA Astrophysics Data System (ADS)

    Kostyuk, D. N.; Gennadiev, A. N.

    2014-06-01

    The results of field studies of the soil cover within the tourist part of the Valley of Geysers in Kamchatka performed in 2010 and 2011 are discussed. The morphology of soils, their genesis, and their dependence on the degree of hydrothermal impact are characterized; the soil cover patterns developing in the valley are analyzed. On the basis of the materials provided by the Kronotskii Biospheric Reserve and original field data, the soil map of the valley has been developed. The maps of vegetation conditions, soil temperature at the depth of 15 cm, and slopes of the surface have been used for this purpose together with satellite imagery and field descriptions of reference soil profiles. The legend to the soil map includes nine soil units and seven units of parent materials and their textures. Soil names are given according to the classification developed by I.L. Goldfarb (2005) for the soils of hydrothermal fields. The designation of soil horizons follows the new Classification and Diagnostic System of Russian Soils (2004). It is suggested that a new horizon—a thermometamorphic horizon TRM—can be introduced into this system by analogy with other metamorphic (transformed in situ) horizons distinguished in this system. This horizon is typical of the soils partly or completely transformed by hydrothermal impacts.

  18. Risk of Malignancy in Thyroid Nodules 4 cm or Larger

    PubMed Central

    2017-01-01

    Background Several authors have questioned the accuracy of fine-needle aspiration cytology (FNAC) in large nodules. Some surgeons recommend thyroidectomy for nodules ≥4 cm even in the setting of benign FNAC, due to increased risk of malignancy and increased false negative rates in large thyroid nodules. The goal of our study was to evaluate if thyroid nodule size is associated with risk of malignancy, and to evaluate the false negative rate of FNAC for thyroid nodules ≥4 cm in our patient population. Methods This is a retrospective study of 85 patients with 101 thyroid nodules, who underwent thyroidectomy for thyroid nodules measuring ≥4 cm. Results The overall risk of malignancy in nodules ≥4 cm was 9.9%. Nodule size was not associated with risk of malignancy (odds ratio, 1.02) after adjusting for nodule consistency, age, and sex (P=0.6). The false negative rate for FNAC was 0%. Conclusion Nodule size was not associated with risk of malignancy in nodules ≥4 cm in our patient population. FNAC had a false negative rate of 0. Patients with thyroid nodules ≥4 cm and benign cytology should not automatically undergo thyroidectomy. PMID:28181427

  19. How to map soil carbon stocks in highly urbanized regions?

    NASA Astrophysics Data System (ADS)

    Vasenev, V. I.; Stoorvogel, J. J.

    2012-04-01

    -use types (3 non-urban and 3 urban) was organized in Moscow region in 2010-2011 (n=242). Both topsoil (0-10 cm) and subsoil (10-150 cm) were included.SOC content for each point was analyzed and this data was incorporated with the information on climatic (annual temperature and precipitation), elevation, land-use, soil (dominating type and soil complexes) factors. The validation of the SOC map, created using regression kriging, demonstrated low accuracy, caused by principal differences in SOC spatial distribution between non-urban and urban areas. Extremely high variability in very short distances (30-50 m) shown for the latter was obviously not possible to interpolate for the whole region territory. In order to consider this internal variability urban areas was described from the total dataset and the heterogeneity index, based on the ratio of functional zones, sealed and open areas and cut-off profiles, was estimated per settlement and district. Thus, the regional SOC map was combined from traditional regression kriging outcome for agricultural areas and aggregated internal variability estimation results for urban ones.

  20. Acidification of soil-water in low base-saturated sand soils of the superior uplands under acid and normal precipitation.

    PubMed

    Harris, A R

    1989-04-01

    Lakes and streams are acidified by direct precipitation and water channeled through nearby soils, but water in low base-saturation soils can produce highly acidic percolate after prolonged contact and subsequent degassing in surface waters. Theories advanced by Reuss (1983), Reuss and Johnson (1985), and Seip and Rustad (1984) suggest that soils with less than 15% base saturation are susceptible to soil-water pH depression of up to 0.4 unit, which is sufficient to cause negative alkalinity in soil solutions. High concentrations of mobile anions (notably sulfate) are responsible for the negative alkalinity and these solutions on CO2 degassing in surface waters can retain acidities equivalent to a pH value of 5.0 or less. This mechanism purports to explain why some lakes acidify when they are surrounded by acid soils and cation leaching is not required.Ambient precipitation set to pH 5.4 and pH 4.2 was applied to columns of low base-saturated, sand, soils, starting in 1985. The columns (15 cm diameter and 150 cm long) were collected from soils with base saturations falling into one of three groups (0-10, 10-20, and 20-40%) from national forests in the Superior Uplands area (includes Boundary Waters Canoe Area, Rainbow Lakes, Sylvania, Moquah Barrens, and other Wilderness and Natural areas). The soils were Haplorthods and Udipsamments mainly from outwash plains.The soil columns were instrumented and reburied around a subterranean structure used to collect leachate water and to maintain natural temperature, air, and light conditions. Three humus treatments were applied to soil column (none, northern hardwood, and jack pine) to measure the effect of natural acidification compared to acidification by acid precipitation. The cores were treated with precipitation buffered to pH 5.4 to simulate natural rain and pH 4.2 to simulate acid rain.Columns were treated in 1985 and 1986 with approximately 200 cm of buffered precipitation each year over the frost-free season. Data is

  1. Occurrence and fate of the norsesquiterpene glucoside ptaquiloside (PTA) in soils

    NASA Astrophysics Data System (ADS)

    Zaccone, Claudio; Cavoski, Ivana; Costi, Roberta; Sarais, Giorgia; Caboni, Pierluigi; Miano, Teodoro M.; Lattanzio, Vincenzo

    2014-05-01

    The bracken fern Pteridium aquilinum (L.) Kuhn, one of the most common plant species on Earth, produces a wide range of secondary metabolites including the norsesquiterpene glucoside ptaquiloside (PTA). This bracken constituent causes acute poisoning, blindness and cancer in animals, and can be transferred to man when bracken is utilized as food. Also milk from cows eating bracken is thought to be the vector for the transfer of PTA to humans, as well as PTA-contaminated drinking waters. Although some studies on the effect of growth conditions and soil properties on the production and mobility of PTA have been carried out (mainly in the North of Europe), results are sometimes conflicting and further investigations are needed. The aim of the present work is to study the occurrence and the fate of PTA in soils showing different physico-chemical features, collected in different pedoclimatic areas (from the South of Italy), but having the extensive ("wild") livestock farming as common denominator. The PTA content was determined in both soil and fern samples by GC-MS; both the extraction protocol and recovery were previously tested through incubation studies. Soils samples were also characterizes from the physical and chemical point of view (pH, EC, texture, total carbonates, cation exchange capacity, organic C, total N, available nutrients and heavy metal concentration) in order to correlate the possible influence of soil parameters on PTA production, occurrence and mobility. PTA concentration in soil samples was always soil organic matter content (ranging from 3.4 to 22.8%), iii) the soil pH (ranging from 5.9 to 6.6), iv) the soil texture, v) the depth (0-10 cm; 10-20 cm), and vi) precipitations (ranging from 780 to 960 mm/a). This seems to suggest the degradation of the PTA by indigenous microbial community

  2. The role of tree uprooting dynamics on the dynamics of Fe (Mn, Al and Si) forms in different forest soils

    NASA Astrophysics Data System (ADS)

    Tejnecký, V.; Samonil, P.; Boruvka, L.; Nikodem, A.; Drabek, O.; Valtera, M.

    2013-12-01

    Tree uprooting dynamics plays an important role in the development of forest ecosystems. This process causes bioturbation of soils and creates new microenvironments which consist of pits and mounds. These microtopographical forms could persist for some thousands of years. Pits and mounds undergo different pedogenesis in comparison to adjacent undisturbed soils. The stage of pedogenesis can be assessed according to the results of fractionation of Fe and also partially Mn, Al and Si. The main aim of this contribution is to assess the fractionation of Fe, Mn, Al and Si for three different soil regions. Soil samples were collected at three localities occurred along hypothetical gradient of soil weathering and leaching processes: The first was a (spruce)-fir-beech natural forest in the Razula region. The second location is the same type of natural forest in Zofin; however it has contrasting lithology. Both these natural forests are located in the Czech Republic (CZ). The third forest was a northern hardwood forest in Upper Peninsula, Michigan, USA. The prevailing soil types - Haplic Cambisols have formed on flysch parent materials in the Razula reserve; Entic Podzols have developed on granite residuum at the Zofin reserve, and Albic Podzols occurred in outwash parent materials at the Michigan sites (Šamonil et al., in press). In total 790 soil samples were analysed. These samples were collected from 5 depths (0-10, 15, 30, 50 and 100 cm) within the pit, mound and control, currently undisturbed position. For each sample, content of Fe (and Mn, Al, Si) forms: exchangeable, crystalline, and amorphous together with organically complexed Fe were determined. We generally observed an increased content of Fe soil forms in the pits of studied treethrows. The content of Fe forms increased along depth gradient at the disturbed sites. However, exchangeable Fe was most abundant in the 0-10cm layer which corresponds to the A horizon. Naturally, if present, the E horizon exhibited

  3. Variations in Soil Microbial Biomass Carbon and Soil Dissolved Organic Carbon in the Re-Vegetation of Hilly Slopes with Purple Soil

    PubMed Central

    Yang, Ning; Zou, Dongsheng; Yang, Manyuan; Lin, Zhonggui

    2016-01-01

    Crust restoration is increasingly being done but we lack quantitative information on soil improvements. The study aimed to elucidate the dynamics involving soil microbial biomass carbon and soil dissolved organic carbon in the re-vegetation chronosequences of a hillslope land with purple soil in Hengyang, Hunan Province. The soil can cause serious disasters with both soil erosion and seasonal drought, and also becomes a typical representative of ecological disaster area in South China. Using the space-for-time method, we selected six typical sampling plots, designated as follows: grassplot community, meadow thicket community, frutex community, frutex and arbor community, arbor community, and top-level vegetation community. These plots were established to analyze the changes in soil microbial biomass carbon, soil microbial quotien, dissolved organic carbon, dissolved organic carbon/soil organic carbon, and soil basal respiration in 0–10, 10–20, and 20–40 cm soil layers. The relationships of these parameters with soils physic-chemical properties were also determined. The ecological environment of the 6 plant communities is similar and typical; they denoted six different successive stages of restoration on hillslopes with purple soils in Hengyang, Hunan Province. The soil microbial biomass carbon and soil basal respiration contents decreased with increasing soil depth but increased with re-vegetation. By contrast, soil microbial quotient increased with increasing soil depth and re-vegetation. From 0–10 cm soil layer to 20–40 cm soil layer, the dissolved organic carbon content decreased in different re-vegetation stages. In the process of re-vegetation, the dissolved organic carbon content increased in the 0–10 and 10–20 cm soil layers, whereas the dissolved organic carbon content decreased after an initial increase in the 20–40 cm soil layers. Meanwhile, dissolved organic carbon/soil organic carbon increased with increasing soil depth but decreased

  4. The Effects of Vegetation Succession and Landscape on the Evolution of Soil Properties: A Chronosequence Study Along the Proglacial Area of Skaftafellsjökull Glacier, SE Iceland

    NASA Astrophysics Data System (ADS)

    Vilmundardóttir, O. K.; Gísladóttir, G.; Lal, R.

    2014-12-01

    On young soils developing along the recessional path left by the Skaftafellsjökull glacier, SE-Iceland, we investigated the soil development, vegetation succession and landscape representing an age chronosequence of 120 years. In total, 54 sampling sites were distributed along three moraines representing surfaces exposed for 8, 65 and 120 years. For comparison, soil samples were collected from nearby birch woodlands, representing soils in a mature ecosystem likely to establish on the moraines in the future. The youngest moraines were sparsely vegetated with only 10% cover of mosses and grasses. The plant cover increased to 67% after 120 years, and was characterized by mosses (38%), dwarf shrubs (20%) and low growing birch (3.5%). Consequently, the soil formed over 120 years contained 1.1 kg C m-2 in the surface layer (0-10 cm), or about one third of the 3.2 kg C m-2 in soil under the woodlands. The N stock was estimated at 0.06 kg N m-2after 120 yrs, almost one fourth of that under the woodlands. The data suggest that landscape affects vegetation establishment and in turn, both landscape and vegetation affect soil development. Thus, concentrations of soil organic carbon (SOC), N and noncrystalline oxalate extractable Al and Fe were higher within depressions than on ridges and slopes. The comparison of SOC stock in the moraine-derived soils with that under the birch woodlands showed that the young proglacial soils still have a large potential to accrete SOC within the developing pedosphere. With the observed accrual rate of 9.1 g C m-2 yr-1in the top 10 cm, it may take the moraine soils an additional 220 yrs to accrue SOC stocks comparable with those under the birch forest. Given the fact that all Icelandic glaciers are receding, assessing SOC sequestration in new soil formation may be important to off-setting some of anthropogenic emissions. The research is funded by the University of Iceland Doctoral Fund, the University of Iceland Trust Fund, the Landsvirkjun

  5. Evaluating management-induced soil salinization in golf courses in semi-arid landscapes

    NASA Astrophysics Data System (ADS)

    Young, J.; Udeigwe, T. K.; Weindorf, D. C.; Kandakji, T.; Gautam, P.; Mahmoud, M. A.

    2015-04-01

    Site-specific information on land management practices are often desired to make better assessments of their environmental impacts. A study was conducted in Lubbock, Texas, in the Southern High Plains of the United States, an area characterized by semi-arid climatic conditions, to (1) examine the potential management-induced alterations in soil salinity indicators in golf course facilities and (2) develop predictive relationships for a more rapid soil salinity examination within these urban landscape soils using findings from a portable X-ray fluorescence (PXRF) spectrometer. Soil samples were collected from managed (well irrigated) and non-managed (non-irrigated) areas of seven golf course facilities at 0-10, 10-20, and 20-30 cm depths and analyzed for a suite of chemical properties. Among the extractable cations, sodium (Na) was significantly (p < 0.05) higher in the managed zones of all the golf facilities. Soil electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), parameters often used in characterizing soil salinity and sodicity, were for the most part significantly (p < 0.05) higher in the managed areas. Water quality reports collected over a 22-year period (1991-2013, all years not available) indicated a gradual increase in pH, EC, SAR, total alkalinity, and extractable ions, thus supporting the former findings. Findings from the PXRF suggested possible differences in chemical species and sources that contribute to salinity between the managed and non-managed zones. PXRF-quantified Cl and S, and to a lesser extent Ca, individually and collectively explained 23-85% of the variability associated with soil salinity at these facilities.

  6. Evaluating management-induced soil salinization in golf courses in semi-arid landscapes

    NASA Astrophysics Data System (ADS)

    Young, J.; Udeigwe, T. K.; Weindorf, D. C.; Kandakji, T.; Gautam, P.; Mahmoud, M. M. A.

    2015-01-01

    Site-specific information on land management practices are often desired to make better assertions of their environmental impacts. A study was conducted in Lubbock, TX, in the Southern High Plains of the United States, an area characterized by semi-arid climatic conditions, to (1) examine the potential management-induced alteration in soil salinity indicators in golf course facilities and (2) develop predictive relationships for a more rapid soil salinity examination within these urban landscape soils using findings from portable x-ray fluorescence (PXRF) spectrometer. Soil samples were collected from the managed (well irrigated) and non-managed (non irrigated) areas of seven golf course facilities at 0-10, 10-20, and 20-30 cm depths, and analyzed for a suite of chemical properties. Among the extractable cations, sodium (Na) was significantly (p < 0.05) higher in the managed zones of all the golf facilities. Soil electrical conductivity (EC), exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), parameters often used in characterizing soil salinity and sodicity, were in most part significantly (p < 0.05) higher in the managed areas. Water quality report collected over a 22-year period (1991-2013, all years not available) indicated a gradual increase in pH, EC, SAR, total alkalinity, and extractable ions, thus, supporting the former findings. Findings from the PXRF suggested possible differences in chemical species and sources that contribute to salinity between the managed and non-managed zones. PXRF quantified Cl and S, and to a lesser extent Ca, individually and collectively explained 23-85% of the variability associated with soil salinity at these facilities.

  7. Cosmic Ray Neutron Probe Soil Water Measurements over Complex Terrain in Austria

    NASA Astrophysics Data System (ADS)

    Vreugdenhil, Mariette; Weltin, Georg; Kheng Heng, Lee; Wahbi, Ammar; Oismueller, Markus; Dercon, Gerd

    2014-05-01

    The importance of surface soil water (rooting zone) has become evident with climate change affecting rainfall patterns and crop production. The use of Cosmic Ray Neutron Probe (CRNP) for measuring surface soil water has become increasingly popular. The advantage of CRNP is that it is a non-invasive technique for measuring soil water content at an area-wide scale, in contrast to more conventional, techniques which measure mainly at field scale (point level). The CRNP integrates over a circular area of ca. 600 meters in diameter, to a depth of 70 cm, giving an average value for soil water content. Cosmic radiation interacting with the Earth's atmosphere continuously generates neutrons. At Earth's surface, these neutrons interact with surface water, and are slowed down. At sub-micrometer geometrics, these neutrons affect semiconductor devices, so they can be counted, slow and fast ones separately. From the difference in numbers between fast and slow neutrons, soil water content is calculated. As first in Austria, a CRNP (CRS 1000/B model) consisting of two neutron counters (one tuned for slow, the other one for fast neutrons), data logger and an Iridium modem, has been installed at Petzenkirchen research station of the Doctoral Programme for Water Resource Systems (TU Vienna) at 48.14 latitude and 15.17 longitude, 100 km west of Vienna, in late autumn 2013. The research station is located in an undulating agricultural landscape, characterized by heavy Cambisols and Planosols, and winter wheat and barley as main crops in winter, and maize and sunflower in summer. In addition, an in-situ soil moisture network consisting of 32 stations of Time Domain Transmissivity (TDT) sensors measuring soil water at 4 depths (0.05, 0.10,0.20 and 0.50 m) over an area of 64 ha has been established. This TDT network is currently being used to validate the use of the innovative CRNP technique. First results will be shown at the EGU 2014.

  8. Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA.

    PubMed

    Deverel, Steven J; Ingrum, Timothy; Leighton, David

    Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr(-1). Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr(-1) where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from <0.3 to >1.8 cm yr(-1). The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr(-1). These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr(-1).

  9. Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA

    NASA Astrophysics Data System (ADS)

    Deverel, Steven J.; Ingrum, Timothy; Leighton, David

    2016-05-01

    Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr-1. Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr-1 where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from <0.3 to >1.8 cm yr-1. The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr-1. These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr-1.

  10. 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

  11. 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.

  12. Influence of urban land development and subsequent soil rehabilitation on soil aggregates, carbon, and hydraulic conductivity.

    PubMed

    Chen, Yujuan; Day, Susan D; Wick, Abbey F; McGuire, Kevin J

    2014-10-01

    Urban land use change is associated with decreased soil-mediated ecosystem services, including stormwater runoff mitigation and carbon (C) sequestration. To better understand soil structure formation over time and the effects of land use change on surface and subsurface hydrology, we quantified the effects of urban land development and subsequent soil rehabilitation on soil aggregate size distribution and aggregate-associated C and their links to soil hydraulic conductivity. Four treatments [typical practice (A horizon removed, subsoil compacted, A horizon partially replaced), enhanced topsoil (same as typical practice plus tillage), post-development rehabilitated soils (compost incorporation to 60-cm depth in subsoil; A horizon partially replaced plus tillage), and pre-development (undisturbed) soils] were applied to 24 plots in Virginia, USA. All plots were planted with five tree species. After five years, undisturbed surface soils had 26 to 48% higher levels of macroaggregation and 12 to 62% greater macroaggregate-associated C pools than those disturbed by urban land development regardless of whether they were stockpiled and replaced, or tilled. Little difference in aggregate size distribution was observed among treatments in subsurface soils, although rehabilitated soils had the greatest macroaggregate-associated C concentrations and pool sizes. Rehabilitated soils had 48 to 171% greater macroaggregate-associated C pool than the other three treatments. Surface hydraulic conductivity was not affected by soil treatment (ranging from 0.4 to 2.3 cm h(-1)). In deeper regions, post-development rehabilitated soils had about twice the saturated hydraulic conductivity (14.8 and 6.3 cm h(-1) at 10-25 cm and 25-40 cm, respectively) of undisturbed soils and approximately 6-11 times that of soils subjected to typical land development practices. Despite limited effects on soil aggregation, rehabilitation that includes deep compost incorporation and breaking of compacted

  13. An investigation into the occurrence and distribution of polycyclic aromatic hydrocarbons in two soil size fractions at a former industrial site in NE England, UK using in situ PFE-GC-MS.

    PubMed

    Lorenzi, Damien; Cave, Mark; Dean, John R

    2010-12-01

    Polycyclic aromatic hydrocarbon (PAH) concentrations were determined in 16 topsoils (0-10 cm) collected across the site of a former tar works in NE England. The soils were prepared in the laboratory to two different particle size fractions: <250 μm (fraction A) and >250 μm to <2 mm (fraction B). Sixteen priority PAHs were analysed in the soils using in situ pressurised fluid extraction (PFE) followed by gas chromatography-mass spectrometry (GC-MS). The average total PAH concentration in the soils ranged from 9.0 to 1,404 mg/kg (soil fraction A) and from 6.6 to 872 mg/kg (soil fraction B). These concentrations are high compared with other industrially contaminated soils reported in the international literature, indicating that the tar works warrants further investigation/remediation. A predominance of higher-molecular-weight compounds was determined in the samples, suggesting that the PAHs were of pyrogenic (anthropogenic) origin. Statistical comparison (t-test) of the mean total PAH concentrations in soil fractions A and B indicated that there was a significant difference (95% confidence interval) between the fractions in all but two of the soil samples. Additionally, comparisons of the distributions of individual PAHs (i.e. 16 PAHs × 16 soil samples) in soil fractions A and B demonstrated generally higher PAH concentrations in fraction A (i.e. 65.8% of all individual PAH concentrations were higher in soil fraction A). This is important because fraction A corresponds to the particle size thought to be most important in terms of human contact with soils and potential threats to human health.

  14. Characterization and risk assessment of polychlorinated biphenyls in city park soils of Xi'an, China.

    PubMed

    Lu, Hongxuan; Liu, Weiguo

    2015-03-01

    Polychlorinated biphenyl (PCB) concentrations in surface soil samples (0-10 cm) from 23 city parks (8 urban and 15 suburban) from Xi'an, China were presented. The average concentration of Σ7 PCBs among all the sites was 1.68 ng g(-1) dry weight. High detection frequency (100 %) of PCB 28 and PCB 52 suggested wide occurrence of PCB contaminations in Xi'an. Among these PCBs, PCB 28, 52 and 153 were the most dominant compounds (14.9 %, 39.3 % and 9.5 % of the Σ7 PCBs on average, respectively). "Urban fractionation effect" was found in Xi'An. In other words, PCB concentrations were higher in the urban city park soils than those in suburban park soils. The PCB contamination in Xi'an city park soils were at a low level based on the Dutch guideline. However, dioxin-like PCB congeners were detected from 12 parks, which indicated further investigation was urgently required in future. Furthermore, total PCB concentrations were used to evaluate the cancer risk via ingestion, dermal and inhalation and the results showed that the total cancer risk was at the very low level in this area.

  15. [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.

  16. In vitro methane removal by volcanic pumice soil biofilter columns over one year.

    PubMed

    Pratt, Chris; Walcroft, Adrian S; Tate, Kevin R; Ross, Des J; Roy, Réal; Reid, Melissa Hills; Veiga, Patricia W

    2012-01-01

    Soil methane (CH(4)) biofilters, containing CH(4)-oxidizing bacteria (methanotrophs), are a promising technology for mitigating greenhouse gas emissions. However, little is known about long-term biofilter performance. In this study, volcanic pumice topsoils (0-10 cm) and subsoils (10-50 cm) were tested for their ability to oxidize a range of CH(4) fluxes over 1 yr. The soils were sampled from an 8-yr-old and a 2-yr-old grassed landfill cover and from a nearby undisturbed pasture away from the influence of CH(4) generated by the decomposing refuse. Methane was passed through the soils in laboratory chambers with fluxes ranging from 0.5 g to 24 g CH(4) m(-3) h(-1). All topsoils efficiently oxidized CH(4). The undisturbed pasture topsoil exhibited the highest removal efficiency (24 g CH(4) m(-3) h(-1)), indicating rapid activation of the methanotroph population to the high CH(4) fluxes. The subsoils were less efficient at oxidizing CH(4) than the topsoils, achieving a maximum rate oxidation rate of 7 g CH(4) m(-3) h(-1). The topsoils exhibited higher porosities; moisture contents; surface areas; and total C, N, and available-P concentrations than the subsoils, suggesting that these characteristics strongly influence growth and activity of the CH(4)-oxidizing bacteria. Soil pH values and available-P levels gradually declined during the trial, indicating a need to monitor chemical parameters closely so that adjustments can be made when necessary. However, other key soil physicochemical parameters (moisture, total C, total N) increased over the course of the trial. This study showed that the selected topsoils were capable of continually sustaining high CH(4) removal rates over 1 yr, which is encouraging for the development of biofilters as a low-maintenance greenhouse gas mitigation technology.

  17. 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.

  18. Assimilation of Global Radar Backscatter and Radiometer Brightness Temperature Observations to Improve Soil Moisture and Land Evaporation Estimates

    NASA Technical Reports Server (NTRS)

    Lievens, H.; Martens, B.; Verhoest, N. E. C.; Hahn, S.; Reichle, R. H.; Miralles, D. G.

    2017-01-01

    Active radar backscatter (s?) observations from the Advanced Scatterometer (ASCAT) and passive radiometer brightness temperature (TB) observations from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated either individually or jointly into the Global Land Evaporation Amsterdam Model (GLEAM) to improve its simulations of soil moisture and land evaporation. To enable s? and TB assimilation, GLEAM is coupled to the Water Cloud Model and the L-band Microwave Emission from the Biosphere (L-MEB) model. The innovations, i.e. differences between observations and simulations, are mapped onto the model soil moisture states through an Ensemble Kalman Filter. The validation of surface (0-10 cm) soil moisture simulations over the period 2010-2014 against in situ measurements from the International Soil Moisture Network (ISMN) shows that assimilating s? or TB alone improves the average correlation of seasonal anomalies (Ran) from 0.514 to 0.547 and 0.548, respectively. The joint assimilation further improves Ran to 0.559. Associated enhancements in daily evaporative flux simulations by GLEAM are validated based on measurements from 22 FLUXNET stations. Again, the singular assimilation improves Ran from 0.502 to 0.536 and 0.533, respectively for s? and TB, whereas the best performance is observed for the joint assimilation (Ran = 0.546). These results demonstrate the complementary value of assimilating radar backscatter observations together with brightness temperatures for improving estimates of hydrological variables, as their joint assimilation outperforms the assimilation of each observation type separately.

  19. Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400-1400 cm-1

    NASA Astrophysics Data System (ADS)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Jeys, T. H.

    2016-02-01

    Raman spectra of ammonia (NH3), chlorine (Cl2), hydrogen sulfide (H2S), phosgene (COCl2), and sulfur dioxide (SO2) toxic gases have been measured in the fingerprint region 400-1400 cm-1. A relatively compact (<2'x2'x2'), sensitive, 532 nm 10 W CW Raman system with double-pass laser and double-sided collection was used for these measurements. Two Raman modes are observed at 934 and 967 cm-1 in NH3. Three Raman modes are observed in Cl2 at 554, 547, and 539 cm-1, which are due to the 35/35 35/37, and 37/37 Cl isotopes, respectively. Raman modes are observed at 870, 570, and 1151 cm-1 in H2S, COCl2, and SO2, respectively. Values of 3.68 ± 0.26x10-32 cm2/sr (3.68 ± 0.26x10-36 m2/sr), 1.37 ± 0.10x10-30 cm2/sr (1.37 ± 0.10x10-34 m2/sr), 3.25 ± 0.23x10-31 cm2/sr (3.25 ± 0.23x10-35 m2/sr), 1.63 ± 0.14x10-30 cm2/sr (1.63 ± 0.14x10-34 m2/sr), and 3.08 ± 0.22x10-30 cm2/sr (and 3.08 ± 0.22x10-34 m2/sr) were determined for the differential Raman cross section of the 967 cm-1 mode of NH3, sum of the 554, 547, and 539 cm-1 modes of Cl2, 870 cm-1 mode of H2S, 570 cm-1 mode of COCl2, and 1151 cm-1 mode of SO2, respectively, using the differential Raman cross section of 3.56 ± 0.14x10-31 cm2/sr (3.56 ± 0.14x10-35 m2/sr) for the 1285 cm-1 mode of CO2 as the reference.

  20. Self-irradiation effect on thermal conductivity of Zr0.70Pu0.25Cm0.05N solid solution

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Hayashi, Hirokazu; Sato, Takumi; Takano, Masahide

    2017-04-01

    This study evaluated the dependence of the thermal conductivity of Zr0.70Pu0.25Cm0.05N on storage time and temperature. The authors prepared sintered samples of Zr0.70Pu0.25Cm0.05N solid solution and measured thermal diffusivity at storage times of 0, 24, 72, 144, 240, 408, 552, 816, 1,680, and 2064 h, from which it was determined that the thermal conductivity decreased exponentially with increasing storage time. This result suggests that the decrease of the thermal conductivity could be attributed to the accumulation of lattice defects from self-irradiation. To confirm the thermal recovery behavior of Zr0.70Pu0.25Cm0.05N under annealing, thermal diffusivity was also measured just after annealing. The thermal conductivity of Zr0.70Pu0.25Cm0.05N was determined to be larger than that of Zr0.58Pu0.21Cm0.21N but smaller than that of Zr0.80Pu0.10Cm0.10N.

  1. Soil organic carbon covariance with soil water content; a geostatistical analysis in cropland fields

    NASA Astrophysics Data System (ADS)

    Manns, H. R.; Berg, A. A.; von Bertoldi, P.

    2013-12-01

    Soil texture has traditionally represented the rate of soil water drainage influencing soil water content (WC) in the soil characteristic curves, hydrological models and remote sensing field studies. Although soil organic carbon (OC) has been shown to significantly increase the water holding capacity of soil in individual field studies, evidence is required to consider soil OC as a significant factor in soil WC variability at the scale of a remote sensing footprint (25 km2). The relationship of soil OC to soil WC was evaluated over 50 fields during the Soil Moisture Active Passive (SMAP) soil WC field sampling campaign over southern Manitoba, Canada. On each field, soil WC was measured at 16 sample points, at 100 m spacing to 5 cm depth with Stevens hydra probe sensors on 16 sampling dates from June 7 to July 19, 2012. Soil cores were also taken at sampling sites on each field, each sampling day, to determine gravimetric moisture, bulk density and particle size distribution. On 4 of the sampling dates, soil OC was also determined by loss on ignition on the dried soil samples from all fields. Semivariograms were created from the field mean soil OC and field mean surface soil WC sampled at midrow, over all cropland fields and averaged over all sampling dates. The semivariogram models explained a distinct relationship of both soil OC and WC within the soil over a range of 5 km with a Gaussian curve. The variance in soil that soil OC and WC have in common was a similar Gaussian curve in the cross variogram. Following spatial interpolation with Kriging, the spatial maps of soil OC and WC were also very similar with high covariance over the majority of the sampling area. The close correlation between soil OC and WC suggests they are structurally related in the soil. Soil carbon could thus assist in improving downscaling methods for remotely sensed soil WC and act as a surrogate for interpolation of soil WC.

  2. Soil Quality of Restinga Forest: Organic Matter and Aluminum Saturation

    NASA Astrophysics Data System (ADS)

    Rodrigues Almeida Filho, Jasse; Casagrande, José Carlos; Martins Bonilha, Rodolfo; Soares, Marcio Roberto; Silva, Luiz Gabriel; Colato, Alexandre

    2013-04-01

    The restinga vegetation (sand coastal plain vegetation) consists of a mosaic of plant communities, which are defined by the characteristics of the substrates, resulting from the type and age of the depositional processes. This mosaic complex of vegetation types comprises restinga forest in advanced (high restinga) and medium regeneration stages (low restinga), each with particular differentiating vegetation characteristics. Of all ecosystems of the Atlantic Forest, restinga is the most fragile and susceptible to anthropic disturbances. The purpose of this study was evaluating the organic matter and aluminum saturation effects on soil quality index (SQI). Two locations were studied: State Park of the Serra do Mar, Picinguaba, in the city of Ubatuba (23°20' e 23°22' S / 44°48' e 44°52' W), and State Park of Cardoso Island in the city of Cananéia (25°03'05" e 25°18'18" S / 47°53'48" e 48° 05'42" W). The soil samples were collect at a depth of 0-10 cm, where concentrate 70% of vegetation root system. Was studied an additive model to evaluate soil quality index. The shallow root system development occurs due to low calcium levels, whose disability limits their development, but also can reflect on delay, restriction or even in the failure of the development vegetation. The organic matter is kept in the soil restinga ecosystem by high acidity, which reduces the decomposition of soil organic matter, which is very poor in nutrients. The base saturation, less than 10, was low due to low amounts of Na, K, Ca and Mg, indicating low nutritional reserve into the soil, due to very high rainfall and sandy texture, resulting in high saturation values for aluminum. Considering the critical threshold to 3% organic matter and for aluminum saturation to 40%, the IQS ranged from 0.95 to 0.1 as increased aluminum saturation and decreased the soil organic matter, indicating the main limitation to the growth of plants in this type of soil, when deforested.

  3. Soil organic carbon distribution in roadside soils of Singapore.

    PubMed

    Ghosh, Subhadip; Scharenbroch, Bryant C; Ow, Lai Fern

    2016-12-01

    Soil is the largest pool of organic carbon in terrestrial systems and plays a key role in carbon cycle. Global population living in urban areas are increasing substantially; however, the effects of urbanization on soil carbon storage and distribution are largely unknown. Here, we characterized the soil organic carbon (SOC) in roadside soils across the city-state of Singapore. We tested three hypotheses that SOC contents (concentration and density) in Singapore would be positively related to aboveground tree biomass, soil microbial biomass and land-use patterns. Overall mean SOC concentrations and densities (0-100 cm) of Singapore's roadside soils were 29 g kg(-1) (4-106 g kg(-1)) and 11 kg m(-2) (1.1-42.5 kg m(-2)) with median values of 26 g kg(-1) and 10 kg m(-2), respectively. There was significantly higher concentration of organic carbon (10.3 g kg(-1)) in the top 0-30 cm soil depth compared to the deeper (30-50 cm, and 50-100 cm) soil depths. Singapore's roadside soils represent 4% of Singapore's land, but store 2.9 million Mg C (estimated range of 0.3-11 million Mg C). This amount of SOC is equivalent to 25% of annual anthropogenic C emissions in Singapore. Soil organic C contents in Singapore's soils were not related to aboveground vegetation or soil microbial biomass, whereas land-use patterns to best explain variance in SOC in Singapore's roadside soils. We found SOC in Singapore's roadside soils to be inversely related to urbanization. We conclude that high SOC in Singapore roadside soils are probably due to management, such as specifications of high quality top-soil, high use of irrigation and fertilization and also due to an optimal climate promoting rapid growth and biological activity.

  4. Carbon and Nitrogen Storage in Glomalin-Related Soil Protein During Grassland-to- Woodland Succession

    NASA Astrophysics Data System (ADS)

    Ariza, M. C.; Boutton, T. W.; Gonzalez-Chavez, M. C.; Filley, T. R.

    2008-12-01

    Glomalin is a hyphal glycoprotein produced by arbuscular mycorrhizal fungi that has been found to make a significant contribution to soil organic matter and to play a key role in the process of soil aggregation. However, little is known regarding the effects of land cover changes on glomalin storage in soil. To evaluate this, we quantified glomalin in soils along a grassland-to-woodland chronosequence in a subtropical mesquite savanna located in southern Texas. Soil cores (0-10 cm) were collected from remnant grasslands (age 0) and from adjacent woody plant stands (ages 14 to 86 yr). Glomalin-related soil protein (GRSP), operationally defined as Bradford reactive soil protein was extracted from soil as easily extractable glomalin (EE-GRSP) and as total glomalin (T-GRSP). EE-GRSP was extracted from 1 g soil with 8 ml of 20 mM citrate-buffer, pH 7.0 at 121 °C for 30 minutes. T-GRSP was extracted from 1 g soil with 8 ml of 50 mM citrate-buffer, pH 8.0 at 121 °C for 60 minutes; extractions were repeated up to 4 times. Extracts were purified by precipitation at pH 2.5, reconstituted in 0.1 NaOH, dialyzed against dH2O, freeze-dried, and analyzed for %C and N. EE-GRSP concentrations ranged from 1.0-1.4 mg/g in remnant grasslands, and from 1.7-2.3 mg/g in wooded areas. Similarly, T-GRSP concentrations ranged from 1.2-2.6 mg/g in remnant grasslands, and from 2.8-4.3 mg/g. Both GRSP fractions increased linearly during the first 40 years of woody plant encroachment, and then remained relatively constant at approximately 4 mg/g in woody clusters ranging in age from 50-90 years. Carbon and nitrogen concentrations in T-GRSP (C = 10-25%; N = 1-3%) were similar in both remnant grasslands and woody plant stands. C and N in T-GRSP accounted for 6% of total soil organic carbon (SOC) and 5% of soil total N in remnant grasslands, and 4% of both SOC and total N in wooded areas. Our results show that woody plant cover significantly affects GRSP concentrations, likely due to increased

  5. [Effects of variable temperature on organic carbon mineralization in typical limestone soils].

    PubMed

    Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti

    2014-11-01

    Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P < 0.05). While the cumulative mineralization (169.46 mg x kg(-1)) of organic carbon in the limestone soil from forest land (SL) under the variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P < 0.01) positively correlated with daily mineralization of soil organic carbon in both temperature treatments, which implied that

  6. Why is SMOS Drier than the South Fork In-situ Soil Moisture Network?

    NASA Astrophysics Data System (ADS)

    Walker, V. A.; Hornbuckle, B. K.; Cosh, M. H.

    2014-12-01

    Global maps of near-surface soil moisture are currently being produced by the European Space Agency's Soil Moisture and Ocean Salinity (SMOS) satellite mission at 40 km. Within the next few months NASA's Soil Moisture Active Passive (SMAP) satellite mission will begin producing observations of near-surface soil moisture at 10 km. Near-surface soil moisture is the water content of the first 3 to 5 cm of the soil. Observations of near-surface soil moisture are expected to improve weather and climate forecasts. These satellite observations must be validated. We define validation as determining the space/time statistical characteristics of the uncertainty. A standard that has been used for satellite validation is in-situ measurements of near-surface soil moisture made with a network of sensors spanning the extent of a satellite footprint. Such a network of sensors has been established in the South Fork of the Iowa River in Central Iowa by the USDA ARS. Our analysis of data in 2013 indicates that SMOS has a dry bias: SMOS near-surface soil moisture is between 0.05 to 0.10 m^3m^{-3} lower than what is observed by the South Fork network. A dry bias in SMOS observations has also been observed in other regions of North America. There are many possible explanations for this difference: underestimation of vegetation, or soil surface roughness; undetected radio frequency interference (RFI); a retrieval model that is not appropriate for agricultural areas; or the use of an incorrect surface temperature in the retrieval process. We will begin our investigation by testing this last possibility: that SMOS is using a surface temperature that is too low which results in a drier soil moisture that compensates for this error. We will present a comparison of surface temperatures from the European Center for Medium-range Weather Forecasting (ECMWF) used to retrieve near-surface soil moisture from SMOS measurements of brightness temperature, and surface temperatures in the South Fork

  7. The GLOBE Soil Moisture Campaign's Light Bulb Oven

    NASA Astrophysics Data System (ADS)

    Whitaker, M. P.; Tietema, D.; Ferre, T. P.; Nijssen, B.; Washburne, J.

    2003-12-01

    The GLOBE Soil Moisture Campaign (SMC) (www.hwr.arizona.edu/globe/sci/SM/SMC) has developed a light bulb oven to provide a low budget, low-technology method for drying soil samples. Three different soils were used to compare the ability of the light bulb oven to dry soils against a standard laboratory convection oven. The soils were: 1) a very fine sandy loam (the "Gila" soil); 2) a silty clay (the "Pima" soil); and 3) a sandy soil (the "Sonoran" soil). A large batch of each soil was wetted uniformly in the laboratory. Twelve samples of each soil were placed in the light bulb oven and twelve samples were placed in the standard oven. The average gravimetric soil moisture of the Gila soil was 0.214 g/cm3 for both ovens; the average Pima soil moisture was 0.332 g/cm3 and 0.331 g/cm3 for the traditional and light bulb ovens, respectively; and the Sonoran soil moisture was 0.077 g/cm3 for both ovens. These results demonstrate that the low technology light-bulb oven was able to dry the soil samples as well as a standard laboratory oven, offering the ability to make gravimetric water content measurements when a relatively expensive drying oven is not available.

  8. Spatiotemporal characteristics of soil temperature memory in China from observation

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Zhang, Jingyong

    2016-11-01

    Similar to soil moisture, soil temperature has a memory of atmospheric anomalies. However, soil temperature memory over China is still largely unclear, especially in observation. In this study, we investigate the spatiotemporal characteristics of soil temperature memory over China using subsurface (10-80 cm) and deep (160-320 cm) soil temperature data for 626 stations during the period of 1981 to 2005. The red noise method is adopted to estimate soil temperature memory. Results show that the soil temperature memory differs spatially and varies with soil depth and season. Influenced by climate regimes, soil temperature memory at all six layers (with depths of 10, 20, 40, 80, 160, and 320 cm) shows a similar spatial pattern dominated by a northwest to southeast gradient, with relatively high values over arid and semiarid areas of northwestern part of China and relatively low values over humid and semihumid areas of southeastern part of China. During all four seasons, memory lengths increase with soil depth. The average memory of subsurface soil over China can last several months, and for soil at 320 cm, it can be 1 year or more. We also find that seasonal and regional differences of soil temperature memory are stronger in deep soil layers than those in subsurface soil layers. Our findings suggest that soil temperature memory can offer potential for improving seasonal climate prediction over northwestern China. In the meanwhile, the limitations of the methods used in this study should be recognized.

  9. 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.

  10. 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.

  11. 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.

  12. High-resolution comparative modeling with RosettaCM.

    PubMed

    Song, Yifan; DiMaio, Frank; Wang, Ray Yu-Ruei; Kim, David; Miles, Chris; Brunette, Tj; Thompson, James; Baker, David

    2013-10-08

    We describe an improved method for comparative modeling, RosettaCM, which optimizes a physically realistic all-atom energy function over the conformational space defined by homologous structures. Given a set of sequence alignments, RosettaCM assembles topologies by recombining aligned segments in Cartesian space and building unaligned regions de novo in torsion space. The junctions between segments are regularized using a loop closure method combining fragment superposition with gradient-based minimization. The energies of the resulting models are optimized by all-atom refinement, and the most representative low-energy model is selected. The CASP10 experiment suggests that RosettaCM yields models with more accurate side-chain and backbone conformations than other methods when the sequence identity to the templates is greater than ∼15%.

  13. Influence of forest stands on soil and ecosystem carbon stocks in the conditions of the European part of Russia

    NASA Astrophysics Data System (ADS)

    Kaganov, Vladimir

    2016-04-01

    carbon stocks were higher for the forestry vegetation than for the reference plots for all studied sites. Maximal values of carbon stocks (779±2 t C ha-1) were observed in forest sites of the forest-steppe zone (Voronezh region). These values decreased while moving both north and south and amounted for 236±1 t C ha-1 in south taiga (Novgorod region) and 104,5±7,4 t C ha-1 in semi-desert areas (Astrakhan region). The stock of total soil carbon significantly increased in 0-10 cm soil layer and decreased in 50-100 cm layer in the forest stands compared to the grass vegetation (T-test at significance level of 0.05). However, when considering the entire 100-cm layer of soil, there is no statistically significant difference in total carbon stock between forest and grass vegetation.

  14. 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. This paper presents the cycle life test results and also 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.

  15. 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.

  16. 21 cm radiation: A new probe of fundamental physics

    NASA Astrophysics Data System (ADS)

    Khatri, Rishi; Wandelt, Benjamin D.

    2010-11-01

    New low frequency radio telescopes currently being built open up the possibility of observing the 21 cm radiation from redshifts 200 > z > 30, also known as the dark ages, see Furlanetto, Oh, & Briggs(2006) for a review. At these high redshifts, Cosmic Microwave Background (CMB) radiation is absorbed by neutral hydrogen at its 21 cm hyperfine transition. This redshifted 21 cm signal thus carries information about the state of the early Universe and can be used to test fundamental physics. The 21 cm radiation probes a volume of the early Universe on kpc scales in contrast with CMB which probes a surface (of some finite thickness) on Mpc scales. Thus there is many orders of more information available, in principle, from the 21 cm observations of dark ages. We have studied the constraints these observations can put on the variation of fundamental constants (Khatri & Wandelt(2007)). Since the 21 cm signal depends on atomic physics it is very sensitive to the variations in the fine structure constant and can place constraints comparable to or better than the other astrophysical experiments (Δα/α= < 10-5) as shown in Figure 1. Making such observations will require radio telescopes of collecting area 10 - 106 km2 compared to ~ 1 km2 of current telescopes, for example LOFAR. We should also expect similar sensitivity to the electron to proton mass ratio. One of the challenges in observing this 21 cm cosmological signal is the presence of the synchrotron foregrounds which is many orders of magnitude larger than the cosmological signal but the two can be separated because of their different statistical nature (Zaldarriaga, Furlanetto, & Hernquist(2004)). Terrestrial EM interference from radio/TV etc. and Earth's ionosphere poses problems for telescopes on ground which may be solved by going to the Moon and there are proposals for doing so, one of which is the Dark Ages Lunar Interferometer (DALI). In conclusion 21 cm cosmology promises a large wealth of data and provides

  17. WSRC Am/Cm Stabilization Program - Cylindrical Induction Melter Studies

    SciTech Connect

    Henderson, W.A.

    1999-02-17

    1.1.1 Kilogram quantities of Americium and Curium isotopes (Am/Cm) have been produced at the U.S. Department of Energy (DOE), Savannah River Site (SRS), Aiken, South Carolina. These highly radioactive isotopes have both government and commercial value and are currently stored as a nitric acid solution at the Savannah River Site. The material represents the largest source term in the F canyon at SRS. It is proposed that the Am/Cm material be vitrified to stabilize the material for long term, recoverable storage. This paper reviews the progress made during the process development phase of this program using the Cylindrical Induction Melter.

  18. 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.

  19. Increased capabilities of the 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Rawlin, V. K.; Hawkins, C. E.

    1979-01-01

    Some space flight missions require advanced ion thrusters which operate at conditions much different than those for which the baseline 30-cm Hg thruster was developed. Results of initial tests of a 30-cm Hg thruster with two and three grid ion accelerating systems, operated at higher values of both thrust and power and over a greater range of specific impulse than the baseline conditions are presented. Thruster lifetime at increased input power was evaluated both by extended tests and real time spectroscopic measurements.

  20. Inert gas test of two 12-cm magnetostatic thrusters

    NASA Technical Reports Server (NTRS)

    Ramsey, W. D.

    1982-01-01

    Comparative performance tests were conducted with 12 cm line and ring magnetic cusp thrusters. Shell anode and magnetoelectrostatic containment boundary anode configurations were evaluated with each magnet array. The best performance was achieved with the 12-cm ring cusp-shell anode configuration. Argon operation of this configuration produced 65-81 percent mass utilization efficiency at 170-208 watts/single-charged-equivalent (SCE) ampere beam. Xenon test results showed 75-95 percent utilization at 162-188 watts/SCE ampere beam.

  1. Passive microwave soil moisture research

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Oneill, P. E.; Wang, J. R.

    1985-01-01

    The AgRISTARS Soil Moisture Project has made significant progress in the quantification of microwave sensor capabilities for soil moisture remote sensing. The 21-cm wavelength has been verified to be the best single channel for radiometric observations of soil moisture. It has also been found that other remote sensing approaches used in conjunction with L-band passive data are more successful than multiple wavelength microwave radiometry in this application. AgRISTARS studies have also improved current understanding of noise factors affecting the interpretability of microwave emission data. The absorption of soil emission by vegetation has been quantified, although this effect is less important than absorption effects for microwave radiometry.

  2. 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.

  3. Local root abscisic acid (ABA) accumulation depends on the spatial distribution of soil moisture in potato: implications for ABA signalling under heterogeneous soil drying.

    PubMed

    Puértolas, Jaime; Conesa, María R; Ballester, Carlos; Dodd, Ian C

    2015-04-01

    Patterns of root abscisic acid (ABA) accumulation ([ABA]root), root water potential (Ψroot), and root water uptake (RWU), and their impact on xylem sap ABA concentration ([X-ABA]) were measured under vertical partial root-zone drying (VPRD, upper compartment dry, lower compartment wet) and horizontal partial root-zone drying (HPRD, two lateral compartments: one dry, the other wet) of potato (Solanum tuberosum L.). When water was withheld from the dry compartment for 0-10 d, RWU and Ψroot were similarly lower in the dry compartment when soil volumetric water content dropped below 0.22cm(3) cm(-3) for both spatial distributions of soil moisture. However, [ABA]root increased in response to decreasing Ψroot in the dry compartment only for HPRD, resulting in much higher ABA accumulation than in VPRD. The position of the sampled roots (~4cm closer to the surface in the dry compartment of VPRD than in HPRD) might account for this difference, since older (upper) roots may accumulate less ABA in response to decreased Ψroot than younger (deeper) roots. This would explain differences in root ABA accumulation patterns under vertical and horizontal soil moisture gradients reported in the literature. In our experiment, these differences in root ABA accumulation did not influence [X-ABA], since the RWU fraction (and thus ABA export to shoots) from the dry compartment dramatically decreased simultaneously with any increase in [ABA]root. Thus, HPRD might better trigger a long-distance ABA signal than VPRD under conditions allowing simultaneous high [ABA]root and relatively high RWU fraction.

  4. 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

  5. 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.

  6. A study of Cs-137 spatial distribution in soil thin sections by digital autoradiography

    NASA Astrophysics Data System (ADS)

    Korobova, Elena; Dogadkin, Nikolay; Shiryaev, Andrey; Kolotov, Vladimir; Turkov, Victor

    2013-04-01

    Recent studies have proved autoradiography to have high potential in detection of radiation in particles including geological objects [1-3]. We applied digital autoradiography based on usage of image plates to study Cs-137 microdistribution in thin sections of the podzolic sandy soil typical for the Chernobyl remote impact zone 25 years after the accident. The zone is noted for contamination of the so-called condensation type where the contribution of the "hot" fuel particles has been comparatively low. The initial 137Cs contamination level of the study plot approximated 40 Ci/km2. According to the soil core data twenty five years after the accident the main portion of cesium radioisotopes is still concentrated in the 10-20 cm thick surface layer. Thin sections have been prepared from the top 0-10 cm soil layer of the soil profile located on the shoulder of the relatively steep northern slope of the forested hill formed on the Iput river terrace ca 20 km to the east of the town of Novozybkov, Bryansk region. Undisturbed soil sample was impregnated with epoxy resin, then dissected in vertical triplicates and polished to obtain open surface. Autoradiography of the thin sections has clearly shown different patterns of Cs-137 distribution related to its concentration in organic material and on the surface of soil particles. High sensitivity and resolution of the applied technique enables to reveal concentration and dispersion zones on microscale level. Soil micro-morphology has shown to be helpful in deciphering soil components and properties responsible for Cs-137 retention in the soil top layer. References 1. Mihoko Hareyama, Noriyoshi Tsuchiya, Masahiro Takebe and Tadashi Chida. Two-dimensional measurement of natural radioactivity of granitic rocks by photostimulated luminescence technique Geochemical Journal, 2000, 34, 1- 9. 2. Zeissler C. J., R. M. Lindstrom, J. P. McKinley. Radioactive particle analysis by digital autoradiography. Journal of Radioanalytical and

  7. 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 ...

  8. Nitrogen fertilizer increases nitrous oxide, but not dinitrogen, emissions from moist tropical forest soils in Puerto Rico

    NASA Astrophysics Data System (ADS)

    Almaraz, M.; Porder, S.; Groffman, P. M.

    2015-12-01

    Nitrogen (N) deposition in tropical forests may increase substantially in coming decades, stimulating a concomitant increase of soil N gas emissions (dinitrogen (N2), nitrous (N2O) and nitric oxides). How N deposition might alter the relative emissions of these gases is unclear, and has ramifications for the global climate since N2O is a potent greenhouse gas. We used a small-scale fertilization study in the Luquillo Experimental Forest (LEF) of Puerto Rico to simulate the effects of N deposition on N gas emissions. Fertilizer was applied by placing mesh bags filled with ammonium saturated weak cation exchange resin directly on the mineral soil for two months. At that time, intact soil cores (0-10cm) were taken from below the bags. The cores were shipped to the Cary Institute of Ecosystem Studies, where they were incubated in a helium headspace with either 0 or 20% oxygen (O2), and analyzed for N2 and N2O emissions. N fertilization increased N2O emissions fourfold (p=0.03). N2O production was positively correlated with field soil moisture (r=0.45, p=0.002), and was higher under 20% than 0% atmospheric O2 (p=0.003). With the exception of a handful of samples, we detected no measureable N2 production from these soils, and fertilization did not influence N2 production. This may have been because our experiment occurred during a drought that reduced soil moisture in the field by ˜20%. We have found that N2 emissions correlate with soil moisture elsewhere in the LEF. While we conclude that N deposition may not influence the N2O:N2 of soil emissions under such conditions, it is still unclear whether this result would hold under higher rainfall.

  9. Soil temperature prediction from air temperature for alluvial soils in lower Indo-Gangetic plain

    NASA Astrophysics Data System (ADS)

    Barman, D.; Kundu, D. K.; Pal, Soumen; Pal, Susanto; Chakraborty, A. K.; Jha, A. K.; Mazumdar, S. P.; Saha, R.; Bhattacharyya, P.

    2017-01-01

    Soil temperature is an important factor in biogeochemical processes. On-site monitoring of soil temperature is limited in spatiotemporal scale as compared to air temperature data inventories due to various management difficulties. Therefore, empirical models were developed by taking 30-year long-term (1985-2014) air and soil temperature data for prediction of soil temperatures at three depths (5, 15, 30 cm) in morning (0636 Indian standard time) and afternoon (1336 Indian standard time) for alluvial soils in lower Indo-Gangetic plain. At 5 cm depth, power and exponential regression models were best fitted for daily data in morning and afternoon, respectively, but it was reverse at 15 cm. However, at 30 cm, exponential models were best fitted for both the times. Regression analysis revealed that in morning for all three depths and in afternoon for 30 cm depth, soil temperatures (daily, weekly, and monthly) could be predicted more efficiently with the help of corresponding mean air temperature than that of maximum and minimum. However, in afternoon, prediction of soil temperature at 5 and 15 cm depths were more precised for all the time intervals when maximum air temperature was used, except for weekly soil temperature at 15 cm, where the use of mean air temperature gave better prediction.

  10. Sayama CM2 Chondrite: Fresh but Heavily Altered

    NASA Technical Reports Server (NTRS)

    Takaoka, N.; Nakamura, T.; Noguchi, T.; Tonui, E.; Gounelle, M.; Zolensky, M. E.; Ebisawa, N.; Osawa, T.; Okazaki, R.; Nagao, K.; Yoneda, S.

    2001-01-01

    Noble gas composition and mineralogy of Sayama meteorite, that fell in Japan and recently identified as a CM2 chondrite, revealed many unique features, indicating that it experienced extensive aqueous alteration under highly oxidized condition compared with typical CMs. Additional information is contained in the original extended abstract.

  11. 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.

  12. Organic Matter Inclusions in CM2 Chondrite Murchison

    NASA Astrophysics Data System (ADS)

    Peeters, Z.; Liebig, B.; Lee, T.

    2015-07-01

    Large (~10 μm) inclusions of pure organic carbon exist in carbonaceous chondrites. We extracted organic inclusions from Murchison, a CM2, and analyzed the sections using XANES, TEM, and nanoSIMS. The results are compared to previous results of CRs.

  13. 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.

  14. 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.

  15. 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…

  16. Case study: developing product lines using ICD-9-CM codes.

    PubMed

    Benz, P D; Burnham, J

    1985-12-01

    In this marketing case study, Thomas Jefferson University Hospital used a product line approach to maximize the use of its resources. The method used, based on ICD-9-CM codes, fulfilled the demands of increased efficiency by encouraging customer-oriented thinking, enhancing communication with physicians and patients, and helping the institution to compete more effectively.

  17. Oxygen isotope constraints on the alteration temperatures of CM chondrites

    NASA Astrophysics Data System (ADS)

    Verdier-Paoletti, Maximilien J.; Marrocchi, Yves; Avice, Guillaume; Roskosz, Mathieu; Gurenko, Andrey; Gounelle, Matthieu

    2017-01-01

    We report a systematic oxygen isotopic survey of Ca-carbonates in nine different CM chondrites characterized by different degrees of alteration, from the least altered known to date (Paris, 2.7-2.8) to the most altered (ALH 88045, CM1). Our data define a continuous trend that crosses the Terrestrial Fractionation Line (TFL), with a general relationship that is indistinguishable within errors from the trend defined by both matrix phyllosilicates and bulk O-isotopic compositions of CM chondrites. This bulk-matrix-carbonate (BMC) trend does not correspond to a mass-dependent fractionation (i.e., slope 0.52) as it would be expected during fluid circulation along a temperature gradient. It is instead a direct proxy of the degree of O-isotopic equilibration between 17,18O-rich fluids and 16O-rich anhydrous minerals. Our O-isotopic survey revealed that, for a given CM, no carbonate is in O-isotopic equilibrium with its respective surrounding matrix. This precludes direct calculation of the temperature of carbonate precipitation. However, the O-isotopic compositions of alteration water in different CMs (inferred from isotopic mass-balance calculation and direct measurements) define another trend (CMW for CM Water), parallel to BMC but with a different intercept. The distance between the BMC and CMW trends is directly related to the temperature of CM alteration and corresponds to average carbonates and serpentine formation temperatures of 110 °C and 75 °C, respectively. However, carbonate O-isotopic variations around the BMC trend indicate that they formed at various temperatures ranging between 50 and 300 °C, with 50% of the carbonates studied here showing precipitation temperature higher than 100 °C. The average Δ17O and the average carbonate precipitation temperature per chondrite are correlated, revealing that all CMs underwent similar maximum temperature peaks, but that altered CMs experienced protracted carbonate precipitation event(s) at lower temperatures than

  18. 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.

  19. Fallow Effects on Improving Soil Properties and Decreasing Erosion: Atlantic Forest, Southeastern Brazil

    NASA Astrophysics Data System (ADS)

    Miranda, J. P.; Silva, L. M.; Lima, R. L.; Donagemma, G. K.; Bertolino, A. V. A.; Fernandes, N. F.; Correa, F. M.; Polidoro, J. C.; Tato, G.

    2009-04-01

    fallow) and forest. For each case, 12 soil samples were collected at 4 depths: 0-5, 5-10, 10-20 and 20-30cm, with 3 repetitions, leading to a total of 60 soil samples, where the following properties were characterized: porosity (micro, macro and total), bulk density and aggregate stability. Besides, in situ measurements of saturated hydraulic conductivity were conducted with a Guelph permeameter. The results obtained in this study attested that all the soil properties analyzed were affected by soil usage, especially at shallow depths, in particular macroporosity and total porosity, which have major influences on infiltration rates, runoff and soil erosion. Besides, the results suggested that the 5-year fallow (F5) was able to recover from 72% to 100% of total porosity for the 0-10cm depth layer (considering forest values as reference), while in the 2-year fallow (F2) this recovery was lower, ranging from 66 to 80%. A similar trend was observed for macroporosity, showing recovering values from 60% to 90% and from 50% to 76%, for F5 and F2, respectively. However, aggregate stability values did not show significant variations between the two fallows. Saturated hydraulic conductivity, on the other hand, presented the lowest recovering values for all the studied properties: between 13% and 58% for F5 and between 6% and 33% for F2. Comparing to the natural forest (reference value), the coffee plantations presented the worst soil conditions in terms of soil hydrology and erosion. The results presented here attested important improvements in soil physical and hydrological properties after a 5-year fallow, leading to decrease in surface runoff and soil erosion in the area.

  20. Tests of the Tully-Fisher relation. 1: Scatter in infrared magnitude versus 21 cm width

    NASA Technical Reports Server (NTRS)

    Bernstein, Gary M.; Guhathakurta, Puragra; Raychaudhury, Somak; Giovanelli, Riccardo; Haynes, Martha P.; Herter, Terry; Vogt, Nicole P.

    1994-01-01

    We examine the precision of the Tully-Fisher relation (TFR) using a sample of galaxies in the Coma region of the sky, and find that it is good to 5% or better in measuring relative distances. Total magnitudes and disk axis ratios are derived from H and I band surface photometry, and Arecibo 21 cm profiles define the rotation speeds of the galaxies. Using 25 galaxies for which the disk inclination and 21 cm width are well defined, we find an rms deviation of 0.10 mag from a linear TFR with dI/d(log W(sub c)) = -5.6. Each galaxy is assumed to be at a distance proportional to its redshift, and an extinction correction of 1.4(1-b/a) mag is applied to the total I magnitude. The measured scatter is less than 0.15 mag using milder extinction laws from the literature. The I band TFR scatter is consistent with measurement error, and the 95% CL limits on the intrinsic scatter are 0-0.10 mag. The rms scatter using H band magnitudes is 0.20 mag (N = 17). The low width galaxies have scatter in H significantly in excess of known measurement error, but the higher width half of the galaxies have scatter consistent with measurement error. The H band TFR slope may be as steep as the I band slope. As the first applications of this tight correlation, we note the following: (1) the data for the particular spirals commonly used to define the TFR distance to the Coma cluster are inconsistent with being at a common distance and are in fact in free Hubble expansion, with an upper limit of 300 km/s on the rms peculiar line-of-sight velocity of these gas-rich spirals; and (2) the gravitational potential in the disks of these galaxies has typical ellipticity less than 5%. The published data for three nearby spiral galaxies with Cepheid distance determinations are inconsistent with our Coma TFR, suggesting that these local calibrators are either ill-measured or peculiar relative to the Coma Supercluster spirals, or that the TFR has a varying form in different locales.

  1. Bells and Essebi: To Be or Not To Be (CM)

    NASA Astrophysics Data System (ADS)

    Kallemeyn, G. W.

    1995-09-01

    The Bells and Essebi carbonaceous chondrites have long been associated with the CM group, although petrographic and isotopic observations have questioned that relationship. Samples of Bells and Essebi were obtained for bulk compositional study by neutron activation analysis (INAA) in an attempt to further fuel the debate on this issue. The current INAA work for Bells is complete, but analysis of Essebi is ongoing, and therefore the data is preliminary. Although CM chondrites typically contain <3 wt% magnetite, Bells and Essebi contain approximately 16 wt% and 11 wt% magnetite, respectively [1]. Both Bells and Essebi seem to have suffered more intense aqueous alteration than typical CM chondrites [2]. Bells has a phyllosilicate matrix composition closer to CI chondrites than CM chondrites [3]. The delta 15N value for Bells is much higher than any of the established carbonaceous chondrite groups[4]. Carbonate material in Essebi has delta 13C compositions (+62 per mil to +80 per mil) higher than the CM mode of +40 per mil to +50 per mil [5]. Both Bells and Essebi have whole rock O-isotope compositions in the CM chondrite range, but Essebi has separated matrix and magnetite values similar to whole rock and magnetite values in CI chondrites [6]. Samples of Bells were from two different stones collected after the fall. One stone was collected the day after the fall, the other was collected several days later after a hurricane went through the area. The samples will be referred to as 'normal' Bells and 'weathered' Bells, respectively. The 'normal' and 'weathered' Bells samples are very similar in composition with a few notable exceptions. The Mg-normalized abundances of Na, K and Br in 'weathered' Bells are markedly depleted relative to 'normal' Bells. The abundance of Ca is also lower to a smaller extent. One must be cautious of compositional studies of late-collected Bells specimens as they may have been altered by the affects of rainwater. Refractory lithophile

  2. Soil warming alters microbial substrate use in alpine soils.

    PubMed

    Streit, Kathrin; Hagedorn, Frank; Hiltbrunner, David; Portmann, Magdalena; Saurer, Matthias; Buchmann, Nina; Wild, Birgit; Richter, Andreas; Wipf, Sonja; Siegwolf, Rolf T W

    2014-04-01

    Will warming lead to an increased use of older soil organic carbon (SOC) by microbial communities, thereby inducing C losses from C-rich alpine soils? We studied soil microbial community composition, activity, and substrate use after 3 and 4 years of soil warming (+4 °C, 2007-2010) at the alpine treeline in Switzerland. The warming experiment was nested in a free air CO2 enrichment experiment using depleted (13)CO2 (δ(13)C = -30‰, 2001-2009). We traced this depleted (13)C label in phospholipid fatty acids (PLFA) of the organic layer (0-5 cm soil depth) and in C mineralized from root-free soils to distinguish substrate ages used by soil microorganisms: fixed before 2001 ('old'), from 2001 to 2009 ('new') or in 2010 ('recent'). Warming induced a sustained stimulation of soil respiration (+38%) without decline in mineralizable SOC. PLFA concentrations did not reveal changes in microbial community composition due to soil warming, but soil microbial metabolic activity was stimulated (+66%). Warming decreased the amount of new and recent C in the fungal biomarker 18:2ω6,9 and the amount of new C mineralized from root-free soils, implying a shift in microbial substrate use toward a greater use of old SOC. This shift in substrate use could indicate an imbalance between C inputs and outputs, which could eventually decrease SOC storage in this alpine ecosystem.

  3. Responses of fine roots and soil N availability to short-term nitrogen fertilization in a broad-leaved Korean pine mixed forest in northeastern China.

    PubMed

    Wang, Cunguo; Han, Shijie; Zhou, Yumei; Yan, Caifeng; Cheng, Xubing; Zheng, Xingbo; Li, Mai-He

    2012-01-01

    Knowledge of the responses of soil nitrogen (N) availability, fine root mass, production and turnover rates to atmospheric N deposition is crucial for understanding fine root dynamics and functioning in forest ecosystems. Fine root biomass and necromass, production and turnover rates, and soil nitrate-N and ammonium-N in relation to N fertilization (50 kg N ha(-1) year(-1)) were investigated in a temperate forest over the growing season of 2010, using sequential soil cores and ingrowth cores methods. N fertilization increased soil nitrate-N by 16% (P<0.001) and ammonium-N by 6% (P<0.01) compared to control plots. Fine root biomass and necromass in 0-20 cm soil were 13% (4.61 vs. 5.23 Mg ha(-1), P<0.001) and 34% (1.39 vs. 1.86 Mg ha(-1), P<0.001) less in N fertilization plots than those in control plots. The fine root mass was significantly negatively correlated with soil N availability and nitrate-N contents, especially in 0-10 cm soil layer. Both fine root production and turnover rates increased with N fertilization, indicating a rapid underground carbon cycling in environment with high nitrogen levels. Although high N supply has been widely recognized to promote aboveground growth rates, the present study suggests that high levels of nitrogen supply may reduce the pool size of the underground carbon. Hence, we conclude that high levels of atmospheric N deposition will stimulate the belowground carbon cycling, leading to changes in the carbon balance between aboveground and underground storage. The implications of the present study suggest that carbon model and prediction need to take the effects of nitrogen deposition on underground system into account.

  4. Fine root dynamics for forests on contrasting soils in the Colombian Amazon

    NASA Astrophysics Data System (ADS)

    Jiménez, E. M.; Moreno, F. H.; Peñuela, M. C.; Patiño, S.; Lloyd, J.

    2009-12-01

    It has been hypothesized that as soil fertility increases, the amount of carbon allocated to below-ground production (fine roots) should decrease. To evaluate this hypothesis, we measured the standing crop fine root mass and the production of fine roots (<2 mm) by two methods: (1) ingrowth cores and, (2) sequential soil coring, during 2.2 years in two lowland forests growing on different soils types in the Colombian Amazon. Differences of soil resources were defined by the type and physical and chemical properties of soil: a forest on clay loam soil (Endostagnic Plinthosol) at the Amacayacu National Natural Park and, the other on white sand (Ortseinc Podzol) at the Zafire Biological Station, located in the Forest Reservation of the Calderón River. We found that the standing crop fine root mass and the production was significantly different between soil depths (0-10 and 10-20 cm) and also between forests. The loamy sand forest allocated more carbon to fine roots than the clay loam forest with the production in loamy sand forest twice (mean±standard error=2.98±0.36 and 3.33±0.69 Mg C ha-1 yr-1, method 1 and 2, respectively) as much as for the more fertile loamy soil forest (1.51±0.14, method 1, and from 1.03±0.31 to 1.36±0.23 Mg C ha-1 yr-1, method 2). Similarly, the average of standing crop fine root mass was higher in the white-sands forest (10.94±0.33 Mg C ha-1) as compared to the forest on the more fertile soil (from 3.04±0.15 to 3.64±0.18 Mg C ha-1). The standing crop fine root mass also showed a temporal pattern related to rainfall, with the production of fine roots decreasing substantially in the dry period of the year 2005. These results suggest that soil resources may play an important role in patterns of carbon allocation to the production of fine roots in these forests as the proportion of carbon allocated to above- and below-ground organs is different between forest types. Thus, a trade-off between above- and below-ground growth seems to exist

  5. Estimating toxic damage to soil ecosystems from soil organic matter profiles

    USGS Publications Warehouse

    Beyer, W.N.

    2001-01-01

    Concentrations of particulate and total organic matter were measured in upper soil profiles at 26 sites as a potential means to identify toxic damage to soil ecosystems. Because soil organic matter plays a role in cycling nutrients, aerating soil, retaining water, and maintaining tilth, a significant reduction in organic matter content in a soil profile is not just evidence of a change in ecosystem function, but of damage to that soil ecosystem. Reference sites were selected for comparison to contaminated sites, and additional sites were selected to illustrate how variables other than environmental contaminants might affect the Soil organic matter profile. The survey was undertaken on the supposition that environmental contaminants and other stressors reduce the activity of earthworms and other macrofauna, inhibiting the incorporation of organic matter into the soil profile. The profiles of the unstressed soils showed a continuous decrease in organic matter content from the uppermost mineral soil layer (0-2.5 cm) down to 15 cm. Stressed soils showed an abrupt decrease in soil organic matter content below a depth of 2.5 cm. The 2.5-5.0 cm layer of stressed soils--such as found in a pine barren, an orchard, sites contaminated with zinc, and a site with compacted soil--had less than 4% total organic matter and less than 1% particulate organic matter. However, damaged soil ecosystems were best identified by comparison of their profiles to the profiles of closely matched reference soils, rather than by comparison to these absolute values. The presence or absence of earthworms offered a partial explanation of observed differences in soil organic matter profiles.

  6. 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.

  7. Initialization of a Numerical Mesoscale Model with ALEXI-derived Volumetric Soil Moisture: Case Results and Validation

    NASA Astrophysics Data System (ADS)

    Mecikalski, J. R.; Hain, C. R.; Anderson, M. C.

    2006-05-01

    Soil moisture plays a vital role in the portioning of sensible and latent heat fluxes in the surface energy budget, although high spatial-resolution observations of it are quite rare. The ALEXI model contains the two-source land-surface representation of Norman et al. (1995), which partitions surface fluxes and radiometric temperature into canopy and soil contributions based on the fraction of vegetation cover within the scene. Anderson et al. (1997) and Mecikalski (1999) detail the implementation of ALEXI as a regional-scale application over the continental United States. This model relies on remote sensing data to operate, including GOES-derived surface brightness temperature changes, AVHRR-derived land cover properties, as well as synoptic weather data to operate (Mecikalski, 1999). This version of the ALEXI algorithm has been run daily on a 10 km resolution grid from the years 2002 to present. ALEXI diagnoses a fraction of potential evapotranspiration (fPET) for both the surface layer (0-5 cm) and root-zone (5-200 cm), given a calculation of the potential ET for each pixel. In current mesoscale modeling the fraction of potential ET can be directly related to a fraction of available water, which in turn can be used to calculate volumetric soil moisture for a given soil texture. Soil moisture conditions of the surface and root-zone yield a distinctive thermal signature, where moisture deficiency will lead to surfaces warming more quickly. Current land-surface models (LDAS, NLDAS) such as those used in the North American Mesoscale Model (NAM) use antecedent precipitation as the primary component to the calculation of volumetric soil moisture. These models use four layers in their soil model (0-10, 10-40, 40-100, and 100-200 cm), while ALEXI provides derived volumetric soil moisture for only two layers within the 0-200 cm depth. This discrepancy can be solved with a blending of the two layers from ALEXI to provide a reasonable representation of the observed

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

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

    DOE PAGES

    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

  14. 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.

  15. Soil Temperature Reemergence in Permafrost

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Schaefer, K.

    2007-12-01

    Soil temperature reemergence is the disappearance and subsequent reappearance of near surface soil temperature anomalies, driven by soil freeze-thaw processes. Reemergence of past soil temperature anomalies is a new class of time-delayed, land-atmosphere feedbacks influencing surface fluxes of latent and sensible heat. Anomalous energy is stored, isolated from diffusion processes, as variations in latent heat of fusion. Schaefer et al. [2007] found that past soil temperature anomalies in seasonally frozen soils are stored as variations in the amount of ground ice and can reemerge at the surface after soil thaw in spring. Schaefer et al. [2007] also hypothesized that temperature anomalies in permafrost would be stored as variations in the active layer depth, reappearing after the soil column completely freezes in winter. Essentially, a warm summer produces a deeper active layer, which requires more energy to freeze in autumn, resulting in warmer soils in winter. Here, we explore this hypothesis using statistical analysis of long-term, in situ soil temperature measurements at 37 permafrost hydro-meteorological stations across Siberia. The observations span 30-40 years at depths of 2-320 cm. We also use a simple soil thermodynamic model with phase changes to explore the detailed thermodynamic processes driving temperature reemergence in permafrost.

  16. How accurately can 21cm tomography constrain cosmology?

    NASA Astrophysics Data System (ADS)

    Mao, Yi; Tegmark, Max; McQuinn, Matthew; Zaldarriaga, Matias; Zahn, Oliver

    2008-07-01

    There is growing interest in using 3-dimensional neutral hydrogen mapping with the redshifted 21 cm line as a cosmological probe. However, its utility depends on many assumptions. To aid experimental planning and design, we quantify how the precision with which cosmological parameters can be measured depends on a broad range of assumptions, focusing on the 21 cm signal from 6cm tomography measured the matter power spectrum directly. A future square kilometer array optimized for 21 cm tomography could improve the sensitivity to spatial curvature and neutrino masses by up to 2 orders of magnitude, to ΔΩk≈0.0002 and Δmν≈0.007eV, and give a 4σ detection of the spectral index running predicted by the simplest inflation models.

  17. The future of primordial features with 21 cm tomography

    NASA Astrophysics Data System (ADS)

    Chen, Xingang; Meerburg, P. Daniel; Münchmeyer, Moritz

    2016-09-01

    Detecting a deviation from a featureless primordial power spectrum of fluctuations would give profound insight into the physics of the primordial Universe. Depending on their nature, primordial features can either provide direct evidence for the inflation scenario or pin down details of the inflation model. Thus far, using the cosmic microwave background (CMB) we have only been able to put stringent constraints on the amplitude of features, but no significant evidence has been found for such signals. Here we explore the limit of the experimental reach in constraining such features using 21 cm tomography at high redshift. A measurement of the 21 cm power spectrum from the Dark Ages is generally considered as the ideal experiment for early Universe physics, with potentially access to a large number of modes. We consider three different categories of theoretically motivated models: the sharp feature models, resonance models, and standard clock models. We study the improvements on bounds on features as a function of the total number of observed modes and identify parameter degeneracies. The detectability depends critically on the amplitude, frequency and scale-location of the features, as well as the angular and redshift resolution of the experiment. We quantify these effects by considering different fiducial models. Our forecast shows that a cosmic variance limited 21 cm experiment measuring fluctuations in the redshift range 30 <= z <= 100 with a 0.01-MHz bandwidth and sub-arcminute angular resolution could potentially improve bounds by several orders of magnitude for most features compared to current Planck bounds. At the same time, 21 cm tomography also opens up a unique window into features that are located on very small scales.

  18. 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.

  19. OH 18 cm TRANSITION AS A THERMOMETER FOR MOLECULAR CLOUDS

    SciTech Connect

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

    2015-12-10

    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 H{sub 2} densities (10{sup 2}–10{sup 7} cm{sup −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 H{sub 2} 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. 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.

  1. 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.

  2. 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.

  3. Am/Cm Vitrification Process: Vitrification Material Balance Calculations

    SciTech Connect

    Smith, F.G.

    2000-08-15

    This report documents material balance calculations for the Americium/Curium vitrification process and describes the basis used to make the calculations. The material balance calculations reported here start with the solution produced by the Am/Cm pretreatment process as described in ``Material Balance Calculations for Am/Cm Pretreatment Process (U)'', SRT-AMC-99-0178 [1]. Following pretreatment, small batches of the product will be further treated with an additional oxalic acid precipitation and washing. The precipitate from each batch will then be charged to the Am/Cm melter with glass cullet and vitrified to produce the final product. The material balance calculations in this report are designed to provide projected compositions of the melter glass and off-gas streams. Except for decanted supernate collected from precipitation and precipitate washing, the flowsheet neglects side streams such as acid washes of empty tanks that would go directly to waste. Complete listings of the results of the material balance calculations are provided in the Appendices to this report.

  4. 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

    carbon content of the topsoil (averaged on the first 50 cm of soil depth) with the table published by Stone and Hilborn (2012). The slope-length and slope gradient (LS) factors were derived from the Digital Terrain Model of Sicily (20 x 20 m) using the formulas proposed by Wischmeier and Smith (1978), and revised by McCool et al. (1987 and 1989). The C factor were applied according previous studies in the same area and ranged among 0.22 and 0.12 and less than 0.10 using permanent species able to reduce erosion rate up to 90% (Gristina et al., 2006; Novara et al. 2011). The scenario analysis of the soil erosion reduction after the adoption of AEM could be used by policy makers as a base for the evaluation of the Payment for Ecosystem Service (PES) to be paid to farmers through the future Agro-Ecosystem measures incentives. Gristina, L., Bagarello, V., Ferro, V., Poma, I., 2006. Cover and management factor for Sicilian vineyard systems. In: 14th International Soil conservation Organization Conference—Water Management and Soil Conservation in Semi-arid Environments, 14-19 May 2006, Marrakech, Marocco (ISCO2006), pp. 1-4. A Novara, L Gristina, SS Saladino, A Santoro, A Cerda 2011 Soil erosion assessment on tillage and alternative soil managements in a Sicilian vineyard. Soil and Tillage Research 117, 140-147

  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. Organic Matter as an Indicator of Soil Degradation

    NASA Astrophysics Data System (ADS)

    Romero Diaz, Asuncion; Damian Ruiz Sinoga, Jose

    2010-05-01

    Numerous and expensive physical-chemical tests are often carried out to determine the level of soil degration. This study was to find one property, as Organic Matter, which is usually analyzed for determine the soil degradation status. To do this 19 areas in the south and southeast of the Iberian Peninsula (provinces of Málaga, Granada, Almería y Murcia) were selected and a wide sampling process was carried out. Sampling points were spread over a wide pluviometric gradient (from 1100 mm/yr to 232 mm/yr) covering the range from Mediterranean wet to dry. 554 soil surface samples were taken from soil (0-10 cm) and the following properties were analyzed: Texture, Organic Matter (OM), Electric Conductivity (EC), Aggregate Stability (AE) y Cation Exchange Capacity (CEC). These properties were intercorrelated and also with rainfall and the K factor of soil erosion, calculated for each sampling point. Los results obtained by applying the Pearson correlation coefficient to the database shows how as rainfall increases so does OM content (0,97) and la CEC (0,89), but K factor (-0,80) reacts inversely. The content of OM in the soil is related to its biological activity and this in turn is the result of available wáter within the system and, consequently, rainfall. This is specially important in fragile and complex ecogeomorphological systems as is the case of the Mediterranean, where greater or lesser rainfall is similarly reflected in the levels of increase or decrease of soil organic matter. This affirmation is reinforced by linking the organic matter of the soil with other indicative properties such as CEC and erosion, as has been shown by various authors (Imeson y Vis, 1984; De Ploey & Poesen, 1985; Le Bissonnais, 1996; Boix-Fayos et al., 2001; Cammeraat y Imeson, 1998; Cerdá, 1998). As has been stated, there is a direct relationship between rainfall, organic matter content, cation exchange capacity, structural stability, and the resistence to soil erosion factor

  7. Land management effects on soil carbon in olive groves of Mediterranean areas

    NASA Astrophysics Data System (ADS)

    Fernández-Romero, Maria Luisa; Parras-Alcántara, Luis; Lozano-García, Beatriz; Clark, Joanna; Collins, Chris

    2015-04-01

    The study analysed soil organic carbon (SOC) and hot-water extractable carbon (HWC) in an agricultural Mediterranean area of Southern Spain under different land management: Conventional tillage (CT); Conventional tillage with the addition of oil mill waste, also known as alperujo (A); Conventional tillage with the addition of oil mill waste olive leaves (L); No tillage with chipped pruned branches (NT1); and No tillage with chipped pruned branches and weeds (NT2). SOC values in CT, A, NT1 and NT2 decreased with depth. In L, SOC also decreased with depth, although there was an increase of 89% from the first (0-10 cm) to the second horizon (10-16 cm). Total SOC stock (considering the entire soil profile) was very similar under A (101.9 Mg ha-1), CT (101.7 Mg ha-1), NT1 (105.8 Mg ha-1) and NT2 (111.3 Mg ha-1). However, SOC under L was significantly higher (p

  8. Herbicide sorption coefficients in relation to soil properties and terrain attributes on a cultivated prairie

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sorption of the herbicides 2,4-D and glyphosate in soil was quantified for 286 surface soil samples (0-15 cm) collected in a 10 m X 10 m grid across a heavily-eroded undulating calcareous prairie landscape. At each sampling point soil organic carbon content, soil carbonate content, soil pH, till...

  9. Concentration of cadmium in cacao beans and its relationship with soil cadmium in southern Ecuador.

    PubMed

    Chavez, E; He, Z L; Stoffella, P J; Mylavarapu, R S; Li, Y C; Moyano, B; Baligar, V C

    2015-11-15

    Cadmium (Cd) content in cacao beans above a critical level (0.6 mg kg(-1)) has raised concerns in the consumption of cacao-based chocolate. Little is available regarding Cd concentration in soil and cacao in Ecuador. The aim of this study was to determine the status of Cd in both, soils and cacao plants, in southern Ecuador. Soil samples were collected from 19 farms at 0-5, 5-15, 15-30, and 30-50 cm depths, whereas plant samples were taken from four nearby trees. Total recoverable and extractable Cd were measured at the different soil depths. Total recoverable Cd ranged from 0.88 to 2.45 and 0.06 to 2.59, averaged 1.54 and 0.85 mg kg(-1), respectively in the surface and subsurface soils whereas the corresponding values for M3-extractable Cd were 0.08 to 1.27 and 0.02 to 0.33 with mean values of 0.40 and 0.10 mg kg(-1). Surface soil in all sampling sites had total recoverable Cd above the USEPA critical level for agricultural soils (0.43 mg kg(-1)), indicating that Cd pollution occurs. Since both total recoverable and M3-extractable Cd significantly decreased depth wise, anthropogenic activities are more likely the source of contamination. Cadmium in cacao tissues decreased in the order of beans>shell>leaves. Cadmium content in cacao beans ranged from 0.02 to 3.00, averaged 0.94 mg kg(-1), and 12 out of 19 sites had bean Cd content above the critical level. Bean Cd concentration was highly correlated with M3- or HCl-extractable Cd at both the 0-5 and 5-15 cm depths (r=0.80 and 0.82 for M3, and r=0.78 and 0.82 for HCl; P<0.01). These results indicate that accumulation of Cd in surface layers results in excessive Cd in cacao beans and M3- or HCl-extractable Cd are suitable methods for predicting available Cd in the studied soils.

  10. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    NASA Astrophysics Data System (ADS)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    (about 10 mm in size) selected per treatment (mulched or conventional tillage) and crop (apricot, citrus and wheat). In this case, every set of aggregates was randomly divided in three groups (n = 30) for assessing stability to slaking, WR and OC, respectively. OC content in the fine earth fraction of soils under different crops did not show important variations, although it increased significantly from conventionally tilled to mulched soils. The distribution of OC content in aggregates with different size varied among soils under different crops, generally increasing with decreasing size. At the intra-aggregate level, OC concentrated preferably in the exterior layer of differently sized aggregates and of aggregate coatings and interior from conventionally tilled soils, probably because of recent organic inputs or leachates. In the case of mulched soils, higher concentrations were observed, but no significant differences among aggregate regions were found. The intensity of water repellency, determined by the ethanol method, did not show great variations among differently sized aggregates under different crops in the 0-10 cm layer, but increased significantly from conventionally tilled to mulched soils. Coarser aggregates were generally wettable, while finer aggregates showed slight water repellency. Regardless of variations in the distribution of OC in different laye