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Sample records for air dried soil

  1. Effects of Soil and Air Drying Methods on Soil Plasticity of Different Cities of Pakistan

    Directory of Open Access Journals (Sweden)

    Aashan Ijaz

    2014-12-01

    Full Text Available Atterberg Limits were initially defined in 1911, by Albert Atterberg, a Swedish scientist. Their purposes are to classifying cohesive soils and determine engineering properties of soils. According to ASTM, all the soils tested by Atterberg limits should be oven dried, it is because drying the soils in different degree will alter their properties significantly. Some of the physical properties of soils will undergo changes that appear to be permanent. Therefore, the soil samples should be in natural or air-dried form. However, in reality, due to time constraint and other factors, many will run the tests by using soil samples that are prepared by oven drying method. They assumed that there is no difference between the results of two types of drying method. However, in reality, the properties of soil will be affected and thus give a misleading result. The objective of this study is to determine the effect of two drying methods, air-drying method and oven drying method, on the soil plasticity. Six soil samples from different cities were tested. These tests include sieve analysis, specific gravity test, hydrometer analysis, Plastic limit and liquid limit test. Conclusively, the oven drying method could not replace the air-drying method in soil preparation for both Atterberg limits tests.

  2. Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area

    International Nuclear Information System (INIS)

    Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle + gas) Σ41-PCB concentrations were higher in summer (3370 ± 1617 pg m-3, average + SD) than in winter (1164 ± 618 pg m-3), probably due to increased volatilization with temperature. Average particulate Σ41-PCBs dry deposition fluxes were 349 ± 183 and 469 ± 328 ng m-2 day-1 in summer and winter, respectively. Overall average particulate deposition velocity was 5.5 ± 3.5 cm s-1. The spatial distribution of Σ41-PCB soil concentrations (n = 48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga. - Determined fluxes indicated that dry deposition and air-soil exchange are equally important mechanisms for movement of PCBs between air and soil in the study area

  3. On the use of a freeze-dried versus an air-dried soil humic acid as a surrogate of soil organic matter for contaminant sorption

    International Nuclear Information System (INIS)

    The sorption of phenanthrene (PHN) to relatively pure soil humic acids (HAs) was investigated to assess the suitability of the soil HA as a surrogate sorbent for the soil organic matter (SOM). The HAs were prepared in both freeze-dried and air-dried forms. The two forms of HAs from the same source are similar in composition but the freeze-dried HAs exhibit a significantly higher initial surface area (SA) (3.86–4.59 m2/g); the SAs of air-dried HAs are below 0.1 m2/g. However, the SAs of freeze-dried HAs are not stable upon contact with water; the samples lose practically all the SA after 4 days of immersion in water. The PHN sorption to both forms of HAs is practically linear, whether a co-solute is present or not. The sorption linearity observed with the present freeze-dried HAs is in sharp contrast with the allegedly nonlinear PHN sorption on similar freeze-dried HAs as presented by others. - Highlights: ► In contrast to the alleged nonlinear sorption of a nonpolar organic pollutant to a freeze-dried humic acid (HA) from water. ► This study shows no evidence for such nonlinearity. ► The initially prepared freeze-dried HA exhibits a significant surface area. ► This artificially created surface area is however unstable upon contact with water. - This study shows no alleged nonlinear sorption of a nonpolar organic pollutant from water to solid humic acids extracted from soils.

  4. Leaching heavy metals from the surface soil of reclaimed tidal flat by alternating seawater inundation and air drying.

    Science.gov (United States)

    Guo, Shi-Hong; Liu, Zhen-Ling; Li, Qu-Sheng; Yang, Ping; Wang, Li-Li; He, Bao-Yan; Xu, Zhi-Min; Ye, Jin-Shao; Zeng, Eddy Y

    2016-08-01

    Leaching experiments were conducted in a greenhouse to simulate seawater leaching combined with alternating seawater inundation and air drying. We investigated the heavy metal release of soils caused by changes associated with seawater inundation/air drying cycles in the reclaimed soils. After the treatment, the contents of all heavy metals (Cd, Pb, Cr, and Cu), except Zn, in surface soil significantly decreased (P carbonate, reducible, and oxidizable fractions also significantly decreased (P carbon decreased the amount of heavy metals in the oxidizable fraction. Furthermore, complexation of chloride ions and competition of cations during seawater inundation and/or leaching decreased the levels of heavy metals in the exchangeable fraction. By contrast, air drying significantly enhanced the concentration of heavy metals in the exchangeable fraction. Therefore, the removal of heavy metals in the exchangeable fraction can be enhanced during subsequent leaching with seawater. PMID:27236846

  5. Persistence of Denitrifying Enzyme Activity in Dried Soils

    OpenAIRE

    Smith, M. Scott; Parsons, Laura L.

    1985-01-01

    The effects of air drying soil on denitrifying enzyme activity, denitrifier numbers, and rates of N gas loss from soil cores were measured. Only 29 and 16% of the initial denitrifying enzyme activity in fresh, near field capacity samples of Maury and Donerail soils, respectively, were lost after 7 days of air drying. The denitrifying activity of bacteria added to soil and activity recently formed in situ were not stable during drying. When dried and moist soil cores were irrigated, evolution ...

  6. The pollution exchange between soil and the near-surface air layer through turbulent transfer, resuspension and dry deposition

    International Nuclear Information System (INIS)

    The exchange of pollutants between the soil and the near-surface boundary layer is considered taking into account the effects of dry deposition, sedimentation and resuspension. The time taken to reach steady-state conditions has been evaluated. The exact solutions of conventional vertical turbulent diffusion with a given lower boundary condition have been derived and analysed. (author)

  7. Drying of a model soil

    Science.gov (United States)

    Faure, P.; Coussot, P.

    2010-09-01

    Drying experiments have been carried out with model soils made of different pastes filling granular packings. A detailed information concerning the time evolution of the water saturation distribution inside the sample was obtained from magnetic resonance imaging measurements. This study makes it possible to understand the physical origin of the drying characteristics of these materials. The drying curves exhibit a constant-rate period (CRP) and a falling-rate period (FRP) but the relative durations of these periods depend on the paste structure. With a kaolin suspension the CRP lasts down to very low water densities and is associated with a homogeneous drying of the paste throughout the sample. With a bentonite suspension the CRP is shorter and the drying in the FRP results from a complex process involving fractures progressing downward through the pasty matrix. With a gel the CRP period is even shorter and the drying in the FRP results from the progression of a dry front through the packing as a result of the shrinkage of the gel matrix. This provides an overview of the main possible processes at work when drying a soil as a function of its components along with some practical means for slowing down drying from soils.

  8. The Relationship Between Soil Air Filled Porosity and Soil Methane Oxidation is Almost Identical in Both Dry and Wet Temperate Eucalypt Forests

    Science.gov (United States)

    Fest, B. J.; Wardlaw, T.; Hinko-Najera, N.; Arndt, S. K.

    2015-12-01

    In order to gain a better understanding of the temporal variation in soil methane (CH4) exchange in temperate evergreen eucalypt forests in south-eastern Australia we measured soil CH4 exchange in high temporal resolution (every 2 hours or less) over two consecutive years (Wombat State Forest, Victoria, AUS) and over one year (Warra, Tasmania, AUS) in two temperate Eucalyptus obliqua (L. Her) forests with contrasting annual precipitation (Wombat State Forest = 870 mm yr-1, Warra = 1700 mm yr-1). Both forests were continuous CH4 sinks with the Victorian site having a sink strength of -1.79 kg CH4 ha-1 yr-1 and the Tasmanian site having a sink strength of -3.83 kg CH4 ha-1 yr-1. Our results show that CH4 uptake was strongly controlled by soil moisture at both sites and explained up to 90% of the temporal variability in CH4 uptake. Furthermore, when soil moisture was expressed as soil air filled porosity (AFP) we were able to predict the CH4 uptake of one site by the linear regression between AFP and CH4 uptake from the other site. Soil temperature only had an apparent control over seasonal variation in CH4 uptake during periods when soil moisture and soil temperature were closely correlated. The fluctuation of the generally low soil nitrogen levels did not influence soil CH4 uptake at either site.

  9. Hot Air Drying of Green Table Olives

    OpenAIRE

    ÖNGEN, Gaye; Sargin, Sayit; Tetik, Derya; Köse, Timur

    2005-01-01

    The characteristics of hot air-drying of green table olives (Domat variety) by using a tray dryer were studied. Air temperature varied from 40 to 70 °C with an air velocity of 1 m/s. Drying rate curves were determined and quality of dried green olives was evaluated by instrumental analysis (bulk density, particle density, porosity, shrinkage, moisture content, water activity, colour value, protein content, oil content, peroxide value and acidity). Consumers’ acceptance test and microbiologica...

  10. Soil methane oxidation in both dry and wet temperate eucalypt forests show near identical relationship with soil air-filled porosity

    OpenAIRE

    Fest, Benedikt J.; Hinko-Najera, Nina; Wardlaw, Tim; Griffith, David W. T.; Livesley, Stephen J.; Arndt, Stefan K.

    2016-01-01

    Well-drained, aerated soils are important sinks for atmospheric methane (CH4) via the process of CH4 oxidation by methane oxidising bacteria (MOB). This terrestrial CH4 sink may contribute towards climate change mitigation, but the impact of changing soil moisture and temperature regimes on CH4 uptake is not well understood in all ecosystems. Temperate eucalypt forests in south-eastern Australia are predicted to experience rapid and extreme changes in rainfall patterns, temperatures and wild ...

  11. Convective Air Drying Characteristics for Thin Layer Carrots

    Directory of Open Access Journals (Sweden)

    Ionut Dumitru Velescu

    2013-11-01

    Full Text Available Introduction: Carrot is one of the most commonly used vegetables for human nutrition due to high vitamin and fibre content. Drying is one of the oldest methods of food preservation, and it represents a very important aspect of food processing. Sun drying is the most common method used to preserve agricultural products in most tropical countries; this technique is extremely weather dependent, and has the problems of contamination with dust, soil, sand particles and insects. Also, the required drying time can be quite long. Therefore, using solar and hot-air dryers, which are far more rapid, providing uniformity and hygiene are inevitable for industrial food drying processes. Aim: This paper presents a kinetic study of convective drying without pre-treatment of carrot. The effects of the temperature of the drying agent, the speed of the drying agent and the thickness of the kinetics of drying the sample of carrots were investigated. Materials and methods: The experiments were carried out with the aid of an installation for drying food products, that is capable of ensuring the temperature of the drying agent (air in the range of +25 ... +125 °C. The drying process was conducted at temperature of 45 °C in first hour of process, 2 hours at 55 °C, and 3 hours at 60 °C. The air velocity was setup  at 1.0 - 2.5 m/s. Carrots were divided into segments of a thickness of 0.4 cm. Two mathematical models available in the literature were fitted to the experimental data. Results: The drying rate increases with temperature and decreases with the sample diameter. The Page model is given better prediction than the Henderson and Pabis model and satisfactorily described drying characteristics of carrot slices. Conclusions: The most important characteristics of carrot required for simulation and optimization of the drying were studied. The values of calculated effective diffusivity for drying at 45, 55 and 60oC of air temperature and 1.0, 1.5, 2.0 and 2.5 m

  12. High strength air-dried aerogels

    Science.gov (United States)

    Coronado, Paul R.; Satcher, Jr., Joe H.

    2012-11-06

    A method for the preparation of high strength air-dried organic aerogels. The method involves the sol-gel polymerization of organic gel precursors, such as resorcinol with formaldehyde (RF) in aqueous solvents with R/C ratios greater than about 1000 and R/F ratios less than about 1:2.1. Using a procedure analogous to the preparation of resorcinol-formaldehyde (RF) aerogels, this approach generates wet gels that can be air dried at ambient temperatures and pressures. The method significantly reduces the time and/or energy required to produce a dried aerogel compared to conventional methods using either supercritical solvent extraction. The air dried gel exhibits typically less than 5% shrinkage.

  13. Effect of air drying on speciation of heavy metals in flooded rice paddies

    Institute of Scientific and Technical Information of China (English)

    Bao Wang; Biao Huang; Yan Bing Qi; Wen You Hu; Wei Xia Sun

    2012-01-01

    Flooded soil samples were collected in the typical area of the Yangtze Delta Region; fractions of heavy metals in flooded and air dried samples were measured with BCR sequential extraction method and atomic absorption spectrometry.In flooded soils,fractions of heavy metals increased in the order of acid soluble < oxidizable < reducible < residual.The acid soluble and reducible fractions significantly decreased but residual fraction significantly increased when the samples were air dried.The data obtained from air dried soil samples could not accurately represent the speciation of heavy metals in flooded field conditions.

  14. Design of dry barriers for containment of contaminants in unsaturated soils

    Energy Technology Data Exchange (ETDEWEB)

    Morris, C.E. [Univ. of Wollongong (Australia); Thomson, B.M.; Stormont, J.C. [Univ. of New Mexico, Albuquerque, NM (United States)

    1997-12-31

    A dry barrier is a region of very dry conditions in unsaturated soil that prevents vertical migration of water created by circulating dry air through the formation. Dry soil creates a barrier to vertical water movement by decreasing the soil`s hydraulic conductivity, a concept also used in capillary barriers. A dry barrier may be a viable method for providing containment of a contaminant plume in a setting with a thick unsaturated zone and dry climate. The principal factors which determine the feasibility of a dry barrier include: (1) an and environment, (2) thick vadose zone, and (3) the ability to circulate air through the vadose zone. This study investigated the technical and economic considerations associated with creating a dry barrier to provide containment of a hypothetical 1 ha aqueous contaminant plume. The concept appears to be competitive with other interim containment methods such as ground freezing.

  15. Air impingement drying of Spirulina Platensis

    Directory of Open Access Journals (Sweden)

    Ram Yamsaengsung

    2010-03-01

    Full Text Available Spirulina is a cyanobacteria filled with therapeutic and nutritive properties that can be easily digested. It contains71% protein by weight and a higher percentage of GLA (Gamma-Linolenic Acid than any other plant. GLA has contributingproperties of reducing blood pressure and blood cholesterol. After harvesting, the Spirulina is drained, sun-dried and driedin a convective oven. During the prolonged rainy season in Southern Thailand, convective drying alone can be very slowand energy consuming. Thus, this research investigated the effect of air-impingement technique on thin-layer drying ofSpirulina. First, the effects of temperature (40, 50, and 60°C and film thickness (2 and 4 mm on the drying rate wereobtained using a lab-scale dryer with a product capacity of 600 g. For an air velocity of 1 m/s, an increase in temperature up to 60°C resulted in an increase of the drying rate, while increasing the film thickness to 4 mm increased the drying time by 50%. In the second part of the study, a pilot-scale impingement dryer (1.2 m x 1.2 m x 1 m was designed and constructed. The dryer consisted of 3 levels and can handle up 2.8 kg of fresh Spirulina per batch when arranged in a 2 mm layer film. The temperature distribution inside the dryer and the effect of air velocity (1.3 and 2.6 m/s on the drying rate were investigated. From thermocouple measurements, the temperature deviation was less than 10% from top level to bottom level when compared to the average value. Moreover, using the specific moisture evaporation rate as the performance indicator, it was found that an air velocity of 2.6 m/s was more efficient than one of 1.3 m/s.

  16. Jambu drying with cold air circulation

    Directory of Open Access Journals (Sweden)

    Alan Franco Barbosa

    2015-06-01

    Full Text Available The purpose of this study was to evaluate the drying process of jambu using cold air which is a technology that can add value to the horticultural food, improve the production rates and help in waste reduction. Initially, the vegetable is washed in water in order to remove residual impurities. Then, the roots are removed. The raw material is sanitized with 200 ppm (mg.L-1 of sodium hypochlorite (10 minutes. Therefore, the final rinse is carried out with a 5 ppm sodium hypochlorite bath for 10 minutes with the subsequent drainage of this water. The cold air-drying of jambu is performed under temperatures around 25 °C using an air conditioning system. A dehumidifier is used in order to reduce the product's relative humidity (54.6 ± 2.87. The process takes place in a room with an area of 4 square meters that remains shut during the process, which lasts a total time of 44 hours. Later, the product is stored in a high protective package to avoid moisture. Jambu centrifugation is not performed because its leaves are fragile. The cold air-dried jambu is in accordance with the current legislation regarding microbiological aspects. Also, it is well accepted by consumers and its centesimal composition is similar to fresh jambu. Other drying techniques can also be applied, such as hot air and ultrasound. Thus, considering sanitary and sensory aspects and chemical composition, the commercialization of dried jambu is feasible in terms of transport and handling.

  17. Design of dry barriers for containment of contaminants in unsaturated soils

    International Nuclear Information System (INIS)

    A dry barrier is a region of very dry conditions in unsaturated soil that prevents vertical migration of water created by circulating dry air through the formation. Dry soil creates a barrier to vertical water movement by decreasing the soil's hydraulic conductivity, a concept also used in capillary barriers. A dry barrier may be a viable method for providing containment of a contaminant plume in a setting with a thick unsaturated zone and dry climate. The principal factors which determine the feasibility of a dry barrier include: (1) an and environment, (2) thick vadose zone, and (3) the ability to circulate air through the vadose zone. This study investigated the technical and economic considerations associated with creating a dry barrier to provide containment of a hypothetical 1 ha aqueous contaminant plume. The concept appears to be competitive with other interim containment methods such as ground freezing

  18. Drier for air-drying coatings

    OpenAIRE

    Micciche, F.; Oostveen, E.A.; Linde, van der, S.J.; Haveren, van, J.

    2003-01-01

    The invention pertains to a drier composition for air-drying alkyd-based coatings, inks, or floor coverings, comprising a combination of the following components: a) a transition metal salt with the formula: (Me )( X )m in which Me is the transition metal; X represents a coordinating ligand; and k- is the valence state of the transition metal and m is the number of ligands X. b) a reducing biomolecule. The reducing biomolecule is in particular ascorbic acid or a derivative thereof, including ...

  19. Dry Air Entrainment into Hurricane Earl

    Science.gov (United States)

    Guillory, Anthony R.; Jedlovec, Gary J.; Atkinson, Robert J.; Hood, Robbie E.; LaFontaine, Frank J.

    2000-01-01

    Hurricane Earl formed in the Gulf of Mexico in September 1998. It quickly was upgraded from a tropical disturbance to tropical storm status and then to a hurricane. Earl possessed hybrid (tropical and extratropical) characteristics throughout its lifetime. The system maintained and erratic track, which led to wide variability in the operational track forecasts. It eventually made landfall on the Florida panhandle on 2 September and raced northeastward. During August and September 1998, NASA conducted the third Convection and Moisture Experiment (CAMEX-3). The experiment was focused on studying hurricanes with an emphasis toward developing a better understanding of their intensification and motion. Earl provides a unique opportunity to utilize high spatial and temporal resolution data collected from the DC-8 and high altitude ER-2 NASA platforms, which flew over Earl as it made landfall. These data can also be put into broader view provided by other instruments from the Geosychronous Operational Environmental Satellites (GOES) and the Tropical Rainfall Measuring Mission (TRMM) satellites. Hurricane Earl was affected by entrainment of dry air from the northwest. Hurricane Isis was intensifying and approaching the Mexican Pacific coast with its associated outflow potentially affecting the inflow into Earl as the storm neared Florida. In addition, a longwave synoptic trough circulation was present over the eastern U.S. Either or both of these could be responsible for the dry air into the system. This paper will focus on identifying the source of the dry by using upper-level wind and moisture fields derived from the GOES 6.7 um water vapor imagery. We will attempt to relate the large-scale observations to those from the NASA aircraft. An infrared instrument onboard the ER-2 also has a similar wavelength and may be able to confirm some of the GOES findings. In addition, a microwave radiometer with 4 channels focused on measuring precipitation and its associated ice

  20. Modelling of air resistance during drying of wood-chips

    OpenAIRE

    Karaj, S.; Barfuss, Isabel; Schalk, J.; Reisinger, G.; Pude, R.; Müller, Joachim

    2011-01-01

    The objective of this study was to investigate the parameters that affect the drying process of wood chips at low air flow conditions. This objective was determined by measuring the air pressure resistance being produced by wood chips by examining different variables such as: air flow rate, air velocity, wood chip size, bulk density, bulk height and porosity. The air flow resistance was measured inside a 3 meter high cylindrical air duct constructed at University of Hohenheim. Physical proper...

  1. Application of Dry Air Drying Techniques on West-East Gas Pipeline Project

    Institute of Scientific and Technical Information of China (English)

    GaoJianguo; XieLigong; DaiZongyu

    2004-01-01

    Based on the pre-eommissioning requirements of gas pipeline, the basic principles and influential factors of dry air drying adopted in long distance gas pipelines, and states in detail the technological flow and the equipment required, etc. are introduced, which will have practical significance in drying operation on gas pipeline.

  2. Drying kinetics and mathematical modeling of hot air drying of coconut coir pith

    OpenAIRE

    Fernando, J. A. K. M.; Amarasinghe, A. D. U. S.

    2016-01-01

    Drying kinetics of coir pith was studied and the properties of compressed coir pith discs were analyzed. Coir pith particles were oven dried in the range of temperatures from 100 to 240 °C and the rehydration ability of compressed coir pith was evaluated by finding the volume expansion. The optimum drying temperature was found to be 140 °C. Hot air drying was carried out to examine the drying kinetics by allowing the coir pith particles to fluidize and circulate inside the drying chamber. Par...

  3. Do we know how plants sense a drying soil?

    Directory of Open Access Journals (Sweden)

    Streck Nereu Augusto

    2004-01-01

    Full Text Available The reduction of crop growth and yield in dry areas is largely due to stomatal closure in response to dry soil, which decreases photosynthesis. However, the mechanism that causes stomatal closure in a drying soil is a controversial issue. Experienced and respected plant physiologists around the world have different views about the primary sensor of soil water shortage in plants. The goal of this review is to present a chronological synthesis about the evidence of the possible candidates for the mechanism by which plants sense a drying soil. Hydraulic signals in the leaves as the mechanism that causes stomatal closure dominated the view on how plants sense a drying soil during the 70?s and the early 80?s. In the middle 80?s, studies suggested that stomatal conductance is better correlated with soil and root water status than with leaf water status. Thus, chemical signals produced in the roots dominated the view on how plants sense a drying soil during the late 80?s and early 90?s. During the second half of the 90?s, however, studies provided evidence that hydraulic signals in the leaves are still better candidates for the mechanism by which plants sense a drying soil. After more than 60 years of studies in plant-water relations, the question raised in the title still has no unanimous answer. This controversial issue is a good research rationale for the current generation of plant physiologists.

  4. Air flow characteristics in an industrial wood pallet drying kiln

    OpenAIRE

    Tzempelikos, Dimitrios; Filios, Andronikos; Margaris, Dionisios

    2013-01-01

    The improvement and optimization of air-distribution systems in drying kilns contributes to the preservation of the quality, safety and shelf life of perishable products. The present study reports on the numerical solution of airflow within a two dimensional drying kiln enclosure loaded with wooden pallets. The performance of air flow field is examined with and without supply of wooden pallets. Different arrangements of the supplied wooden pallets are investigated as well as the use of a ...

  5. Gas Dispersion in Granular Porous Media under Air-Dry and Wet Conditions

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Hamamoto, S; Kawamoto, K;

    2012-01-01

    dispersion and soil physical characteristics. In this study, a series of advection–dispersion experiments was performed on granular porous media to identify the effects of soil column dimensions (length and diameter), particle size and shape, dry bulk density, and moisture content on the magnitude of gas...... dispersion. Glass beads and various sands of different shapes (angular and rounded) with mean particle diameters (d50) ranging from 0.19 to 1.51 mm at both air-dry and variable moisture contents were used as granular porous media. Gas dispersion coefficients and gas dispersivities (a = DH/v, where v is the...... pore-gas velocity) were determined by fitting the advection–dispersion equation to the measured breakthrough curves. For all test conditions, DH increased linearly with v. The test results showed that neither soil column length nor diameter had significant effect on gas dispersivity. Under air...

  6. Dynamics of convective hot air drying of filiform Lagenaria siceraria

    Directory of Open Access Journals (Sweden)

    Zhu Aishi

    2013-01-01

    Full Text Available In this study, a laboratory convective hot air dryer was used for the thin-layer drying of filiform Lagenaria siceraria and the influences of the drying temperature and air velocity on the drying process were investigated. The drying temperature and the air velocity were varied in the range of 60-80°C and 0.6-1.04 m•s-1, respectively. The experimental data of moisture ratio of filiform Lagenaria siceraria were used to fit the mathematical models, and the dynamics parameters such as convective heat transfer coefficient α and mass transfer coefficient kH were calculated. The results showed that the drying temperature and air velocity influenced the drying process significantly. The Logarithmic model showed the best fit to experimental drying data. It was also found that, the air velocity and the drying temperature influence notable on both of the convective heat transfer coefficient α and the mass transfer coefficient kH. With the increase of hot air velocity from 0.423 to 1.120 ms-1, the values of α varied from 111.3 to 157.7 W•m-2•K-1, the values of kH varied from 13.12 to 18.58 g•m-2• s-1•ΔH-1. With the increase of air temperature from 60 to 80°C, the values of α varied between 150.2 and 156.9 W•m-2•K-1, the values of kH varied between 18.26 and 18.75 g•m-2•s-1•ΔH-1.

  7. Machine Learning Assessments of Soil Drying

    Science.gov (United States)

    Coopersmith, E. J.; Minsker, B. S.; Wenzel, C.; Gilmore, B. J.

    2011-12-01

    Agricultural activities require the use of heavy equipment and vehicles on unpaved farmlands. When soil conditions are wet, equipment can cause substantial damage, leaving deep ruts. In extreme cases, implements can sink and become mired, causing considerable delays and expense to extricate the equipment. Farm managers, who are often located remotely, cannot assess sites before allocating equipment, causing considerable difficulty in reliably assessing conditions of countless sites with any reliability and frequency. For example, farmers often trace serpentine paths of over one hundred miles each day to assess the overall status of various tracts of land spanning thirty, forty, or fifty miles in each direction. One means of assessing the moisture content of a field lies in the strategic positioning of remotely-monitored in situ sensors. Unfortunately, land owners are often reluctant to place sensors across their properties due to the significant monetary cost and complexity. This work aspires to overcome these limitations by modeling the process of wetting and drying statistically - remotely assessing field readiness using only information that is publically accessible. Such data includes Nexrad radar and state climate network sensors, as well as Twitter-based reports of field conditions for validation. Three algorithms, classification trees, k-nearest-neighbors, and boosted perceptrons are deployed to deliver statistical field readiness assessments of an agricultural site located in Urbana, IL. Two of the three algorithms performed with 92-94% accuracy, with the majority of misclassifications falling within the calculated margins of error. This demonstrates the feasibility of using a machine learning framework with only public data, knowledge of system memory from previous conditions, and statistical tools to assess "readiness" without the need for real-time, on-site physical observation. Future efforts will produce a workflow assimilating Nexrad, climate network

  8. Influence of Dry Density on Soil-Water Retention Curve of Unsaturated Soils and Its Mechanism Based on Mercury Intrusion Porosimetry

    Institute of Scientific and Technical Information of China (English)

    李博; 陈宇龙

    2016-01-01

    The soil-water retention curve(SWRC)can be used to evaluate the ability of unsaturated soils to attract water at various water contents and suctions. In this study, drying SWRCs for a kind of sandy soil were obtained in the laboratory by using self-modified SWRC apparatus. In addition, the porosity and the pore size distribution of the samples were investigated by a mercury porosimetry test in order to analyze the effect of dry density. Results showed that the soil-water retention of the soil specimens was strongly dependent on the dry density. Under zero suction, soil specimens with a higher dry density exhibited lower initial volumetric water content. The higher the dry density of soil, the more slowly the volumetric water content decreased with the increase of suction. There was a general and consistent trend for a soil specimen to possess a larger air-entry value and residual suction, while smaller slope of SWRC when it had a higher density. This was probably attributed to the presence of smaller inter-connected pores in the soil specimen with a higher dry density. The proportion of large diameter pores decreased in comparison to pores with small diameters in the soil tested. The measured total pore volume of the soil specimen, which had a larger dry density, was lower than that of the relatively loose specimens.

  9. Mineralogy of Antarctica Dry Valley Soils: Implications for Pedogenic Processes on Mars

    Science.gov (United States)

    Quinn, J. E.; Ming, D. W.; Morris, R. V.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Tamppari, L, K.; Smith, P. H.; Zent, A. P.; Archer, P. D., Jr.

    2010-01-01

    The Antarctic Dry Valleys (ADVs) located in the Transantarctic Mountains are the coldest and driest locations on Earth. The mean annual air temperature is -20 C or less and the ADVs receive 100mm or less of precipitation annually in the form of snow. The cold and dry climate in the ADVs is one of the best terrestrial analogs for the climatic conditions on Mars [2]. The soils in the ADVs have been categorized into three soil moisture zones: subxerous, xerous and ultraxerous. The subxerous zone is a coastal region in which soils have ice-cemented permafrost relatively close to the surface. Moisture is available in relatively large amounts and soil temperatures are above freezing throughout the soil profile (above ice permafrost) in summer months. The xerous zone, the most widespread of the three zones, is an inland region with a climate midway between the subxerous and ultraxerous. The soils from this zone have dry permafrost at moderate depths (30-75cm) but have sufficient water in the upper soil horizons to allow leaching of soluble materials. The ultraxerous zone is a high elevation zone, where both temperature and precipitation amounts are very low resulting in dry permafrost throughout the soil profile. The three moisture regime regions are similar to the three microclimatic zones (coastal thaw, inland mixed, stable upland) defined by Marchant and Head.

  10. Cold Vacuum Drying Instrument Air System Design Description (SYS 12)

    Energy Technology Data Exchange (ETDEWEB)

    SHAPLEY, B.J.; TRAN, Y.S.

    2000-06-05

    This system design description (SDD) addresses the instrument air (IA) system of the spent nuclear fuel (SNF). This IA system provides instrument quality air to the Cold Vacuum Drying (CVD) Facility. The IA system is a general service system that supports the operation of the heating, ventilation, and air conditioning (HVAC) system, the process equipment skids, and process instruments in the CVD Facility. The following discussion is limited to the compressor, dryer, piping, and valving that provide the IA as shown in Drawings H-1-82222, Cold Vacuum Drying Facility Mechanical Utilities Compressed & Instrument Air P&ID, and H-1.82161, Cold Vacuum Drying Facility Process Equipment Skid P&ID MCO/Cusk Interface. Figure 1-1 shows the physical location of the 1A system in the CVD Facility.

  11. Cold Vacuum Drying Instrument Air System Design Description. System 12

    International Nuclear Information System (INIS)

    This system design description (SDD) addresses the instrument air (IA) system of the spent nuclear fuel (SNF). This IA system provides instrument quality air to the Cold Vacuum Drying (CVD) Facility. The IA system is a general service system that supports the operation of the heating, ventilation, and air conditioning (HVAC) system, the process equipment skids, and process instruments in the CVD Facility. The following discussion is limited to the compressor, dryer, piping, and valving that provide the IA as shown in Drawings H-1-82222, Cold Vacuum Drying Facility Mechanical Utilities Compressed and Instrument Air PandID, and H-1.82161, Cold Vacuum Drying Facility Process Equipment Skid PandID MCO/Cusk Interface. Figure 1-1 shows the physical location of the 1A system in the CVD Facility

  12. Convective Air Drying Characteristics for Thin Layer Carrots

    OpenAIRE

    Ionut Dumitru Velescu; Ioan Tenu; Petru Carlescu; Vasile Dobre

    2013-01-01

    Introduction: Carrot is one of the most commonly used vegetables for human nutrition due to high vitamin and fibre content. Drying is one of the oldest methods of food preservation, and it represents a very important aspect of food processing. Sun drying is the most common method used to preserve agricultural products in most tropical countries; this technique is extremely weather dependent, and has the problems of contamination with dust, soil, sand particles and insects. Also, the required ...

  13. Dry deposition of polycyclic aromatic hydrocarbons in ambient air

    International Nuclear Information System (INIS)

    Dry deposition and air sampling were undertaken, simultaneously, in the ambient air of an urban site and a petrochemical-industry (PCI) plant by using several dry deposition plates and PS-1 samplers from January to May 1994 in southern Taiwan. The dry deposition plate with a smooth surface was always pointed into the wind. Twenty-one polycyclic aromatic hydrocarbons (PAHs) were analyzed by a gas chromatography/mass spectrometer (GC/MSD). The dry deposition flux of total-PAHs in urban and PCI sites averaged 166 and 211 microg/m2·d, respectively. In general, the PAH dry deposition flux increased with increases in the PAH concentration in the ambient air. The PAH pattern of dry deposition flux in both urban and PCI sites were similar to the pattern measured by the filter of the PS-1 sampler and completely different from the PAH pattern in the gas phase. The higher molecular weight PAHs have higher dry deposition velocities. This is due to the fact that higher molecular weight PAHs primarily associated with the particle phase are deposited mostly by gravitational settling, while the gas phase PAHs were between 0.001 and 0.010 cm/s, only the lower molecular-weight PAHs--Nap and AcPy--had a significant fraction of dry deposition flux contributed by the gas phase. All the remaining higher molecular-weight PAHs had more than 94.5% of their dry deposition flux resulting from the particle phase. This is due to the fact that higher molecular weight PAHs have a greater fraction in the particle phase and the dry deposition velocities of particulates are much higher than those of the gas phase

  14. Determination of the most economical drying schedule and air velocity in softwood drying

    Energy Technology Data Exchange (ETDEWEB)

    Salin, J.G.

    2001-12-01

    Simulation models for conventional softwood drying have been available and have also been used by kiln operators for many years. For instance models for Scots pine and Norway spruce, dried at temperatures below about 80 deg C, are in use in Sweden, Finland and Norway. These models predict drying rates as a function of climate (schedule) and air velocity. The models thus give a direct basis for calculation of instantaneous energy demand for moisture evaporation and ventilation. There is further a direct relationship between the air velocity in the space between the board layers in the kiln stack and the electrical power demand by the circulation fans. Finally, the smaller energy consumption associated with heat losses through kiln walls and the accumulated heat in timber etc. can be estimated with sufficient accuracy. Instantaneous energy costs can thus be calculated for each part of a drying schedule. Capital costs associated with kiln investment and maintenance, personnel, insurance etc can be accounted for as an hourly cost, which is basically independent of whether timber is dried fast or slowly. A slow drying process thus accumulates more capital costs per m 3 timber. In this way it is possible to calculate the total instantaneous drying cost (Euro/m{sup 3}/h or Euro/m3/MC%) and the overall total cost (Euro or Euro/m{sup 3}). Some results obtained with a simulation model equipped with such a cost calculation are presented in the paper. A rapidly increasing drying cost is seen when the final MC is lowered. By minimising the instantaneous cost, an optimal drying schedule can be determined for a given fixed air velocity. Finally an optimal air velocity - constant or varying - can be found in the same way.

  15. Enhancing The Food Product Drying with Air Dehumidified by Zeolite

    OpenAIRE

    M. Djaeni; D. Anggoro; G.W. Santoso; D. Agustina; N. Asiah; Hii, C.L.

    2014-01-01

    The demand of powdered food products such as soups, sauces, dried yeasts and herbal medicine is increasing for consumer convenience. Mostly, these products have been produced with drying process either, direct sunlight, conventional, or modern dryer. The direct sunlight dryer depends on the daily weather both in the product quality and process continuity. Meanwhile, conventional dryer results high energy consumption as well as low product quality due to the introduction of hot air. In additio...

  16. Drying kinetics, rehydration and colour characteristics of convective hot-air drying of carrot slices

    Science.gov (United States)

    Doymaz, İbrahim

    2016-03-01

    The effects of air drying temperature, slice thickness and pre-treatment application on the drying kinetics of carrot slices during convective drying in the range 50-70 °C were investigated. Results indicated that drying time, rehydration ratio and colour characteristics of carrot slices were more affected by drying air temperature, followed by pre-treatment applications. Five thin-layer drying models were applied to describe the drying kinetics. Midilli et al. model was the best model to characterize the drying kinetics of carrot slices. The moisture effective diffusivity calculated from the second Fick's law of diffusion ranged from 3.46 × 10-10 to 1.02 × 10-9 m2/s. The values of activation energy determined from the slope of the Arrhenius plot, ln(D eff ) versus 1/(T + 273.15), were 35.53, 43.42, and 37.75 kJ/mol for blanch, potas and control samples, respectively.

  17. Osmo-air drying of aloe vera gel cubes.

    Science.gov (United States)

    Pisalkar, P S; Jain, N K; Jain, S K

    2011-04-01

    Aloe vera (Aloe barbadensis Miller) cubes of 12.5 × 12.5 × 12.5 mm thick were osmosed for 4 h in sugar syrup of 30, 40 and 50°Brix concentration and temperatures of 30 and 50°C at constant syrup to fruit ratio of 5:1. Osmosed and unosmosed aloe vera samples were hot air dried at 50, 60, 70 and 80°C with constant air velocity of 1.5 m/s. The water loss, solid gain and convective drying behaviour were recorded during experiments. It was observed that water loss and solid gain ranged from 39.2 to 71.3 and 2.7 to 6.3%, respectively during osmo-drying. The moisture diffusivity varied from 2.9 to 8.0 × 10(-9) m²/s and 2.7 to 4.6 × 10(-9) m²/s during air drying of osmosed and unosmosed aloe vera samples, respectively. Drying air temperature and osmosis as pre-treatment affected the water loss, solid gain, diffusivity at -p ≤ 0.01. PMID:21350589

  18. Treatment of air dried archaeological wool textiles from waterlogged environment

    DEFF Research Database (Denmark)

    Scharff, Annemette Bruselius

    2014-01-01

    Air-dried, wet archaeological wool textiles can be flat and stiff with brittle fibers, but is this a permanent collapse or can they regain their size in water? Iron Age textiles were tested comparing the width of dry fibers with the width of fibers treated in water or 70% ethanol. Both liquids...... expanded the fibers and the yarn increased in size, resulting in more flexible and less brittle textiles. This property was kept when the textiles were dried by stepwise dehydration in ethanol, acetone, and white spirit with a final treatment in 5% lanolin. Preliminary tests on brittle textiles can be...

  19. Drying kinetics and mathematical modeling of hot air drying of coconut coir pith.

    Science.gov (United States)

    Fernando, J A K M; Amarasinghe, A D U S

    2016-01-01

    Drying kinetics of coir pith was studied and the properties of compressed coir pith discs were analyzed. Coir pith particles were oven dried in the range of temperatures from 100 to 240 °C and the rehydration ability of compressed coir pith was evaluated by finding the volume expansion. The optimum drying temperature was found to be 140 °C. Hot air drying was carried out to examine the drying kinetics by allowing the coir pith particles to fluidize and circulate inside the drying chamber. Particle motion within the drying chamber closely resembled the particle motion in a flash dryer. The effective moisture diffusivity was found to increase from 1.18 × 10(-8) to 1.37 × 10(-8) m(2)/s with the increase of air velocity from 1.4 to 2.5 m/s respectively. Correlation analysis and residual plots were used to determine the adequacy of existing mathematical models for describing the drying behavior of coir pith. The empirical models, Wang and Singh model and Linear model, were found to be adequate for accurate prediction of drying behavior of coir pith. A new model was proposed by modifying the Wang and Singh model and considering the effect of air velocity. It gave the best correlation between observed and predicted moisture ratio with high value of coefficient of determination (R(2)) and lower values of root mean square error, reduced Chi square (χ(2)) and mean relative deviation (E%). PMID:27390647

  20. The changes of soil physical and chemical properties of Andisols as affected by drying and rewetting processes

    Directory of Open Access Journals (Sweden)

    A. Rahayu

    2015-10-01

    Full Text Available Soils from a toposequence in northern slope of Mt. Kawi, Malang were sampled to study the effect of amorphous content on the irreversible drying properties of the soils. Water, clay, organic-C, and available P contents were measured at field capacity (KL, after air-drying for 2 days (K2 , air-drying for 4 days (K4, oven-drying at 40 °C for 1 day (Ko, as well as after rewetting K2 (KL2; K4 (KL4, and Ko (KLo. The results showed that water, clay, organic-C, and available P contents changed after drying and rewetting processes. Drying process decreased clay content but increased available P content. Clay and water content of the rewetted samples, especially after oven-drying (KLo were lower than at initial field capacity (KL, as indication of irreversible properties. In contrast, available P and organic-C content were higher after drying-rewetting processes. Variation of water, clay, organic-C, and available P contents after drying-rewetting processes were significantly affected by respected properties at initial field capacity. These properties tended to change in accordance to Alo+½Feo content. The effect of Alo+½Feo content, however was statisticaly detected only on the water content at KLo (rewetted after oven-dried and on organic C content at KL2 and KL4 (rewetted after air-dried for 2 and 4 days.

  1. Preparation of Natural Zeolite for Air Dehumidification in Food Drying

    Directory of Open Access Journals (Sweden)

    Mohamad Djaeni

    2015-03-01

    Full Text Available Drying with air dehumidification with solid adsorbent improves the quality of food product as well as energy efficiency. The natural zeolite is one of adsorbent having potential to adsorb the water.  Normally, the material was activated to open the pore, remove the organic impurities, and increase Si/Al rate. Hence, it can enhance the adsorbing capacity. This research studied the activation of natural zeolite mined from Klaten, Indonesia as air dehumidification for food drying. Two different methods were used involving activation by heat and NaOH introduction.  As indicators, the porosity and water loaded were evaluated. Results showed both methods improved the adsorbing capacity significantly. With NaOH, the adsorbing capacity was higher. The simple test in onion and corn drying showed the presence of activated natural zeolite can speed up water evaporation positively. This performance was also comparable with Zeolite 3A

  2. Predicting the water-drop energy required to breakdown dry soil aggregates

    International Nuclear Information System (INIS)

    The raindrop energy required to breakdown dry soil aggregates is an index of structural stability which has been found very useful in modelling soil erosion process and in evaluating the suitability of tillage implements for different soils. The aim of this research was to develop and validate a model for predicting the specific water-drop energy required to breakdown aggregates (D) as influenced by soil properties. Air-dry aggregates (2-4 mm in diameter), collected from 15 surface (0-20 cm) soils in north central Italy were used for this study. The actual and natural log-transformed D values were regressed on the soil properties. Clay content, wilting point moisture content (WP) and percent water-stable aggregates (WSA) > 2.0 mm were good predictors of D. Empirical models developed from either clay content or WP predicted D in 70% of the test soils whereas the model developed from WSA > 2.0 mm predicted D in 90% of the test soils. The correlation coefficients (r) between measured and predicted D were 0.961, 0.963 and 0.997 respectively, for models developed from clay, WP and WSA > 2.0 mm. The validity of these models need to be tested on other soils with a wider variation in properties than those used to developed the models. (author). 42 refs, 5 tabs

  3. Dry coolers and air-condensing units (Review)

    Science.gov (United States)

    Milman, O. O.; Anan'ev, P. A.

    2016-03-01

    The analysis of factors affecting the growth of shortage of freshwater is performed. The state and dynamics of the global market of dry coolers used at electric power plants are investigated. Substantial increase in number and maximum capacity of air-cooled condensers, which have been put into operation in the world in recent years, are noted. The key reasons facilitating the choice of developers of the dry coolers, in particular the independence of the location of thermal power plant from water sources, are enumerated. The main steam turbine heat removal schemes using air cooling are considered, their comparison of thermal efficiency is assessed, and the change of three important parameters, such as surface area of heat transfer, condensate pump flow, and pressure losses in the steam exhaust system, are estimated. It is shown that the most effective is the scheme of direct steam condensation in the heat-exchange tubes, but other schemes also have certain advantages. The air-cooling efficiency may be enhanced much more by using an air-cooling hybrid system: a combination of dry and wet cooling. The basic applied constructive solutions are shown: the arrangement of heat-exchange modules and the types of fans. The optimal mounting design of a fully shopassembled cooling system for heat-exchange modules is represented. Different types of heat-exchange tubes ribbing that take into account the operational features of cooling systems are shown. Heat transfer coefficients of the plants from different manufacturers are compared, and the main reasons for its decline are named. When using evaporative air cooling, it is possible to improve the efficiency of air-cooling units. The factors affecting the faultless performance of dry coolers (DC) and air-condensing units (ACU) and the ways of their elimination are described. A high velocity wind forcing reduces the efficiency of cooling systems and creates preconditions for the development of wind-driven devices. It is noted that

  4. Drying Strategy of Shrimp using Hot Air Convection and Hybrid Infrared Radiation/Hot Air Convection

    Directory of Open Access Journals (Sweden)

    Supawan TIRAWANICHAKUL

    2008-01-01

    Full Text Available The main objective of the research was to study the effect of drying temperatures using infrared irradiation and electric heating convection on dehydration and was to investigate the effect of drying conditions on the quality of the shrimp. Two sizes of fresh shrimp (100 shrimp/kg and 200 shrimp/kg with initial moisture content of 270 - 350 % dry-basis were dried under various conditions while the final moisture content of dried shrimp was in ranges between 20 and 25 % dry-basis. Hot air flow rates of 1.0 -   1.2 m/s, drying temperatures of 40 - 90 °C and infrared intensities of 1,785.7 - 3,571.4 W/m2 were used in these experiments. The experimental results showed that the rate of moisture content transfer of both sizes of shrimps decreased exponentially with drying time while increasing drying temperature significantly affected to the drying kinetics and quality of the shrimps. Effective diffusion coefficients of both shrimps were determined by a diffusion model forming a finite cylindrical shape was in order of 10-7 m2/s and this effective diffusion coefficient value was relatively dependent on the drying temperature compared to the initial moisture content. The quality analysis of dried shrimp using an infrared source and electric heating source found that the redness value (Hunter a-value of dried samples using hybrid infrared radiation and electric heating had a higher colour uniformity than other drying methods. Additionally, shrinkage and rehydration properties were insignificantly different for all drying strategies (p < 0.05 and drying using infrared radiation had higher drying rates compared to electric heat convection, corresponding to relatively low drying times.

  5. Dry deposition modelling of air pollutants over urban areas

    Science.gov (United States)

    Cherin, N.; Roustan, Y.; Seigneur, C.; Musson Genon, L.

    2012-04-01

    More than one-half of the world's inhabitants lives in urban areas. Consequently, the evolution of pollutants inside these urban areas are problems of great concern in air quality studies. Though the dry deposition fluxes of air pollutants, which are known to be significant in the neighborhood of sources of pollution, like urban areas, have not been modeled precisely until recently within urban areas. By reviewing the physics of the processes leading to the dry deposition of air pollutants, it is clear that atmosphere turbulence is crucial for dry deposition. Urban areas, and particularly buildings, are known to significantly impact flow fields and then by extension the dry deposition fluxes. Numerous urban schemes have been developed in the past decades to approximate the effect of the local scale urban elements on drag, heat flux and radiative budget. The most recent urban canopy models are based on quite simple geometries, but sufficiently close to represent the aerodynamic and thermal characteristics of cities. These canopy models are generally intended to parameterize aerodynamic and thermal fields, but not dry deposition. For dry deposition, the current classical "roughness" approach, uses only two representative parameters, z0 and d, namely the roughness length and the zero-plane displacement height to represent urban areas. In this work, an innovative dry deposition model based on the urban canyon concept, is proposed. It considers a single road, bordered by two facing buildings, which are treated separately. It accounts for sub-grid effects of cities, especially a better parameterization of the turbulence scheme, through the use of local mixing length and a more detailled description of the urban area and key parameters within the urban canopy. Three different flow regimes are distinguished in the urban canyon according to the height-to-width ratio: isolated roughness flow, wake interference flow and skimming flow regime. The magnitude of differences in

  6. Insulation Technology in Dry Air and Vacuum for a 72kV Low Pressured Dry Air Insulated Switchgear

    Science.gov (United States)

    Yoshida, Tadahiro; Koga, Hiromi; Harada, Takakazu; Miki, Shinichi; Arioka, Masahiro; Sato, Shinji; Yoshida, Satoru; Inoue, Naoaki; Maruyama, Akihiko; Takeuchi, Toshie

    A new 72kV rated low pressured dry air insulated switchgear applying electromagnetic actuation and function that supports CBM has been developed. First, dielectric characteristics in dry air under lightning impulse application has been investigated at bare and insulator covered electrodes. Dependence of the breakdown electric field strength on the effective area has been clarified to apply the configuration design of the insulation mold for the vacuum interrupter. In addition, moisture volume dependence on surface resistance has been clarified to decide moisture volume in gas pressure tank. Next, a new vacuum circuit breaker (VCB) has been designed. To keep dimensions from former 72kV SF6 gas insulated switchgear, distance between contacts in vacuum interrupter is needed to be shorter than that of former switchgear. Voltage withstand capability between electrodes practically designed for vacuum interrupter has been investigated under dc voltage application simulated the small capacitive current breaking test. Gap configuration including contacts and slits has been optimized and distance has been shortened 11% from former switchgear. As a result, the new low pressured dry air insulated switchgear has been designed comparably in outer size to former SF6 gas insulated switchgear. Using dry air as an insulation medium with low pressure has been able to reduce the environmental burden.

  7. Experimental and theoretical analysis of cracking in drying soils

    OpenAIRE

    Lakshmikantha, M.R.

    2009-01-01

    The thesis focuses on the experimental and theoretical aspects of the process of cracking in drying soils. The results and conclusions were drawn from an exhaustive experimental campaign characterised by innovative multidisciplinary aspects incorporating Fracture Mechanics and classical Soil mechanics, aided with image analysis techniques. A detailed study of the previous works on the topic showed the absence of large scale fully monitored laboratory tests, while the existing studies were per...

  8. Cumulative ventilation air drying potential as an indication of dry mass content in wastewater sludge in a thin-layer solar drying facility

    Science.gov (United States)

    Krawczyk, Piotr

    2013-12-01

    Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

  9. The Impact of Dry Saharan Air on Tropical Cyclone Intensification

    Science.gov (United States)

    Braun, Scott A.

    2012-01-01

    The controversial role of the dry Saharan Air Layer (SAL) on tropical storm intensification in the Atlantic will be addressed. The SAL has been argued in previous studies to have potential positive influences on storm development, but most recent studies have argued for a strong suppressing influence on storm intensification as a result of dry air, high stability, increased vertical wind shear, and microphysical impacts of dust. Here, we focus on observations of Hurricane Helene (2006), which occurred during the NASA African Monsoon Multidisciplinary Activities (NAMMA) experiment. Satellite and airborne observations, combined with global meteorological analyses depict the initial environment of Helene as being dominated by the SAL, although with minimal evidence that the SAL air actually penetrated to the core of the disturbance. Over the next several days, the SAL air quickly moved westward and was gradually replaced by a very dry, dust-free layer associated with subsidence. Despite the wrapping of this very dry air around the storm, Helene intensified steadily to a Category 3 hurricane suggesting that the dry air was unable to significantly slow storm intensification. Several uncertainties remain about the role of the SAL in Helene (and in tropical cyclones in general). To better address these uncertainties, NASA will be conducting a three year airborne campaign called the Hurricane and Severe Storm Sentinel (HS3). The HS3 objectives are: To obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers (that help to isolate tropical disturbances from hostile environments). To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. The mission objectives will be achieved using

  10. Relationship soil-water-plant after the dry season in dry Mediterranean areas

    Science.gov (United States)

    Hueso-González, P.; Jiménez-Donaire, V.; Ruiz-Sinoga, J. D.

    2012-04-01

    Preliminary studies have determined the existence of a pluviometric gradient around Mediterranean system, which varies from 240 to 1 100 mm mean annual rainfall. This gradient has an incidence in the physical, chemical and hydrological properties in soils with the same litology. Empiric results conclude that humid eco-geomorphological systems are controlled by biotic processes, whereas in arid eco-geomorphological systems, are abiotic factors which have more importance in soil degradation processes. The study area of the present work is located in Málaga (Andalusia, Spain), in the southern part of the Natural Park "Sierra Tejeda, Almijara y Alhama". There, the mean annual temperature is around 18 °C and the mean rainfall is 650 mm. Predominant vegetation corresponds to the termomediterranean serie Smilaci Mauritanicae-Querceto Rotundifoliae Sigmetum, typical of basic soils. The aim of this study is to analyse the immediate hydrological response of the soil under different vegetation covers, through the analysis of certain properties, all this, under subhumid ombrotipe. A random choice of ten representative plants has been done. These plants, with different sizes, were located in the same Southern slope. The soil samples were taken right beside the plant log, and also within a distance of 0.4 to 1 metre from them, depending on the plant size. The sampling was carried out between the end of the dry season and the beginning of the wet one, after a 20% of the mean annual rainfall had rained. The physical, chemical and hydrological analyzes -both in the field and the laboratory- were: exchange-base, total carbon, cation exchange capacity, soil infiltration capacity, salt content, hydrophobia, organic matter, soil organic carbon, total nitrogen, wetting profile in bared soil, wetting profile under vegetation cover (shrubland), and p.H. Literature reveals that rainfall affects significantly the edafogenetic factors, regarding the pluviometric gradient level. In the

  11. Development of a distributed air pollutant dry deposition modeling framework

    International Nuclear Information System (INIS)

    A distributed air pollutant dry deposition modeling system was developed with a geographic information system (GIS) to enhance the functionality of i-Tree Eco (i-Tree, 2011). With the developed system, temperature, leaf area index (LAI) and air pollutant concentration in a spatially distributed form can be estimated, and based on these and other input variables, dry deposition of carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter less than 10 microns (PM10) to trees can be spatially quantified. Employing nationally available road network, traffic volume, air pollutant emission/measurement and meteorological data, the developed system provides a framework for the U.S. city managers to identify spatial patterns of urban forest and locate potential areas for future urban forest planting and protection to improve air quality. To exhibit the usability of the framework, a case study was performed for July and August of 2005 in Baltimore, MD. - Highlights: ► A distributed air pollutant dry deposition modeling system was developed. ► The developed system enhances the functionality of i-Tree Eco. ► The developed system employs nationally available input datasets. ► The developed system is transferable to any U.S. city. ► Future planting and protection spots were visually identified in a case study. - Employing nationally available datasets and a GIS, this study will provide urban forest managers in U.S. cities a framework to quantify and visualize urban forest structure and its air pollution removal effect.

  12. Soil N Fluxes in Three Contrasting Dry Tropical Forests

    OpenAIRE

    Naoko Tokuchi; Asami Nakanishi; Chongrak Wachirinrat; Hiroshi Takeda

    2001-01-01

    A comparative study of N fluxes in soil among a dry dipterocarp forest (DDF), a dry evergreen forest (DEF), and a hill evergreen forest (HEF) in Thailand was done. N fluxes in soil were estimated using an ion exchange resin core method and a buried bag method. Soil C and N pools were 38 C Mg/ha/30 cm and 2.5 N Mg/ha/30 cm in DDF, 82 C Mg/ha/30 cm and 6.2 N Mg/ha/30 cm in DEF, and 167 C Mg/ha/30 cm and 9.3 N Mg/ha/30 cm in HEF. Low C concentration in the DDF and DEF sites was compensated by hi...

  13. Combustion gas properties. 2: Natural gas fuel and dry air

    Science.gov (United States)

    Wear, J. D.; Jones, R. E.; Trout, A. M.; Mcbride, B. J.

    1985-01-01

    A series of computations has been made to produce the equilibrium temperature and gas composition for natural gas fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0. Only samples tables and figures are provided in this report. The complete set of tables and figures is provided on four microfiche films supplied with this report.

  14. Plutonium in soil and surface air in Thailand

    International Nuclear Information System (INIS)

    Plutonium in soil and surface air in the central part of Thailand have been underinvestigated. Dissolve the sample in potassium fluoride and pyrosulfate fusions, and precipitate barium sulfate. The plutonium is separated by solvent extraction with HDEHP from perchloric acid medium. Finally the plutonium is coprecipitated with 50 μg of cerium carrier. The precipitate is filtered on a 25 mm. glossy membrane filter with a 0.1 μm pore size, and analyzed with a 300 mm2 surface-barrier detector at about 20 percent counting efficiency. The range of Plutonium-239, 240 in soil were 0.002 to 0.157 pCi/g.dry. Plutonium-239, 240 in surface air in July 1981 were 7.7 +- 2.1 aCi/m3 and lower than the limit of detector from August to November 1981

  15. Anatomical response of olive roots to dry and irrigated soils

    OpenAIRE

    Fernández Luque, José Enrique; Moreno Lucas, Félix; Martín Aranda, José; Rapoport, Hava F.

    1994-01-01

    Root development was examined in roots of young olive trees (Olea europaea L., cv. Manzanillo) grown under wet and dry water regimes. Cross sections at sequential positions were observed along tbe roots axis from the apex up to 18 cm from the root tip at intervals of 3 cm. An index was established to facilitate development comparisons. Complete transition to secondary growth was found closer to the apex in the roots grown in dry soil (at 9 cm) than in the roots grown in watered so...

  16. Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview

    Directory of Open Access Journals (Sweden)

    Xixi Wang

    2015-08-01

    Full Text Available Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function in evaporation is still a challenging topic with significant remaining issues. Thus, an overview of the previous findings will be very beneficial for identifying further research needs that aim to advance our understanding of the vapor flow resistance (VFR effect on soil water evaporation as influenced by characteristics of the dry soil layer (DSL and evaporation zone (EZ. In this regard, six measurement and four modeling studies were overviewed. The results of these overviewed studies, along with the others, affirm the conceptual dynamics of DSL and EZ during drying or wetting processes (but not both within dry sandy soils. The VFR effect tends to linearly increase with DSL thickness (δ when δ < 5 cm and is likely to increase as a logarithmic function of δ when δ ≥ 5 cm. The vaporization-condensation-movement (VCM dynamics in a DSL depend on soil textures: sandy soils can form a thick (10 to 20 cm DSL while sandy clay soils may or may not have a clear DSL; regardless, a DSL can function as a transient EZ, a vapor condensation zone, and/or a vapor transport medium. Based on the overview, further studies will need to generate long-term continuous field data, develop hydraulic functions for very dry soils, and establish an approach to quantify the dynamics and VFR effects of DSLs during wetting-drying cycles as well as take into account such effects  when using conventional (e.g., Penman-Monteith evaporation models.

  17. Spatial variability of soils in a seasonally dry tropical forest

    Science.gov (United States)

    Pulla, Sandeep; Riotte, Jean; Suresh, Hebbalalu; Dattaraja, Handanakere; Sukumar, Raman

    2016-04-01

    Soil structures communities of plants and soil organisms in tropical forests. Understanding the controls of soil spatial variability can therefore potentially inform efforts towards forest restoration. We studied the relationship between soils and lithology, topography, vegetation and fire in a seasonally dry tropical forest in southern India. We extensively sampled soil (available nutrients, Al, pH, and moisture), rocks, relief, woody vegetation, and spatial variation in fire burn frequency in a permanent 50-ha plot. Lower elevation soils tended to be less moist and were depleted in several nutrients and clay. The availability of several nutrients was, in turn, linked to whole-rock chemical composition differences since some lithologies were associated with higher elevations, while the others tended to dominate lower elevations. We suggest that local-scale topography in this region has been shaped by the spatial distribution of lithologies, which differ in their susceptibility to weathering. Nitrogen availability was uncorrelated with the presence of trees belonging to Fabaceae, a family associated with N-fixing species. No effect of burning on soil parameters could be discerned at this scale.

  18. Dry storage of irradiated Magnox fuel in air

    International Nuclear Information System (INIS)

    A description is given of the large dry store for irradiated Magnox fuel at Wylfa. The storage is basically a concrete box 60 x 1 x 4.5m and 2m thick with a capacity of 350t uranium or 28992 fuel elements, and depending upon natural convection of air for cooling. Freshly irradiated fuel is first stored for 150 days in the original CO2 cooled dry stores to reduce irradiation to an acceptable level before being removed to a store skip. Details are given of the layout of the plant, method of transfer and the transfer machine, and the skips. Development work and automatic control of the transfer equipment are also discussed. (U.K.)

  19. DRY CLEANING OF COAL WITH AIR DENSE MEDIUM FLUIDIZED BED

    Institute of Scientific and Technical Information of China (English)

    陈清如; 杨毅; 余智敏; 李建明

    1990-01-01

    This paper deals with the experimental study of dry cleaning of coal with air dense medium fluidized bed. This technique opens up an efficient way of coal separation for vast areas in the country where water resources are in short supply or coals tend to slime seriously in wet process. Tests show that it can separate any kind of coal (6--50mm) efficiently. The probable error E, can reach 0.05--0.08. The separating density can be adjusted in the range of 1.0--2.0 g/cm3. This technique brings about enormous economic benifits.

  20. Application of 3-component model to removal of Cd and Se in continuous batch experiments and effect of soil-drying on mobility of Cd and Se in cultivated soil

    International Nuclear Information System (INIS)

    It is important to investigate the mobility of heavy metal in cultivated soil when soil contamination is considered. In this report cadmium and selenium were focused because they are toxic heavy metals. Cd mainly occurs as cation and Se mainly occurs as anion. Cd and Se were added to cultivated soil and continuous batch experiments were done to investigate their long-term mobility. By applying 3-component (easily soluble fraction, uneasily soluble fraction, and non-soluble fraction) model to the results, we concluded that 3-component model would be good to estimate the long-term mobility of Cd and Se in cultivated soil. After continuous batch experiments, the soil was air-dried or oven-dried to investigate the effect of soil drying and heating. It was revealed that dried and heated soil could release more Cd than wet one and oven-dried soil could release more Cd and Se than air-dried one. It is necessary to consider the effect of soil drying and heating when we investigate the mobility of heavy metal in soil. (author)

  1. Microwave Assisted Hot Air Convective Dehydration of Fish Slice: Drying Characteristics, Energy Aspects and Colour Assessment

    OpenAIRE

    Mohd Rozainee Taib; Pang Soon Ng

    2011-01-01

    Dried fish is commonly produced by convective hot air drying. Microwave technology was presented in this paper to improve both process and product quality. Catfish (order Siluriformes) slices were dehydrated in a microwave assisted hot air convective dehydration (MWHA) system to investigate the effects of microwave power and hot air temperature on drying time, dehydration behaviour, energy consumption and colour of dried fish. Three different microwave power outputs namely medium (373 W), med...

  2. Drying Characteristics and Model of Chinese Hawthorn Using Microwave Coupled with Hot Air

    OpenAIRE

    Hai-Ming Yu; Chun-Cheng Zuo; Qiu-Ju Xie

    2015-01-01

    Microwave coupled with hot air drying kinetics and characteristics of hawthorn slices at different drying hot air temperatures, hot air velocities, and microwave power densities was investigated. The research results showed that drying occurred mainly in the falling rate period and in the accelerating period. Twelve mathematical models were selected to describe and compare the drying kinetics of hawthorn slices. By comparing three criterions including correlation coefficient, chi-square, and ...

  3. Variability of soil moisture memory for wet and dry basins

    Science.gov (United States)

    Rahman, Mohammad Mahfuzur; Lu, Minjiao; Kyi, Khin Htay

    2015-04-01

    Soil moisture memory (SMM) is not only important for atmospheric weather/climate forecasting, but may also be useful in flood and drought prediction. Despite their importance, SMM studies are restricted in certain regions due to the scarcity of soil moisture data. To overcome this limitation, this study explains the variability of SMM in wet and dry basins, and shows an alternative way to predict the basin scale SMM using observed precipitation and potential evapotranspiration information only. This study presents the basin average SMM in the form of a timescale that indicates the duration of significant autocorrelations at 95% confidence intervals. The soil moisture autocorrelations were calculated using observed precipitation, potential evapotranspiration, streamflow and soil moisture data sets simulated using the XinAnJiang (XAJ) model, for 26 river basins across the USA. The XAJ model's capability to simulate seasonal cycles (temporal anomalies) of soil moisture was validated against cycles from the observed data set of the Spoon River basin of Illinois State, USA. Based on the validation experience, the XAJ model was thereafter used to simulate soil moisture data for the analysed basins. Basin scale SMM timescale ranges were computed from 11 to 133 days. The SMM timescale is highly influenced by precipitation variability and exhibits strong seasonality. Dry basins tend to show the highest memory during the winter months (December to February) and lowest in late spring (May). In contrast, wet basins have the lowest memory during winter and early spring (December to April) and highest in the late summer and early autumn (July to September). The SMM timescale displayed an exponential relationship with the basin aridity index, with an r2 value of 0.9. This relationship could be a cheap source of basin scale SMM prediction from widely available observed data sets (actual precipitation and potential evapotranspiration), and thus, could afford some knowledge of SMM

  4. Microwave Assisted Hot Air Convective Dehydration of Fish Slice: Drying Characteristics, Energy Aspects and Colour Assessment

    Directory of Open Access Journals (Sweden)

    Mohd Rozainee Taib

    2011-01-01

    Full Text Available Dried fish is commonly produced by convective hot air drying. Microwave technology was presented in this paper to improve both process and product quality. Catfish (order Siluriformes slices were dehydrated in a microwave assisted hot air convective dehydration (MWHA system to investigate the effects of microwave power and hot air temperature on drying time, dehydration behaviour, energy consumption and colour of dried fish. Three different microwave power outputs namely medium (373 W, medium low (217 W and low (91 W combined with convective hot air temperature of 40°C, 70°C and 130°C accordingly were employed in the drying experiments. Results show that microwave accelerates drying time up to 120 folds faster compared to drying with hot air convective alone. It was also noted that increasing the hot air temperature was not as significant as increasing the microwave power in reducing the drying time. Experiments show that drying time was reduced about 75 % when an increase of microwave power from low (91 W to medium mode (373 W combining with convective hot air. However, drying with microwave alone required longer drying time. Energy consumption analysis shows that microwave assisted drying process requires less energy usage. Drying fish with microwave assisted hot air dehydration treatment make the colour brighter, shifting towards red and yellow.

  5. Gaseous fuels production from dried sewage sludge via air gasification.

    Science.gov (United States)

    Werle, Sebastian; Dudziak, Mariusz

    2014-06-17

    Gasification is a perspective alternative method of dried sewage sludge thermal treatment. For the purpose of experimental investigations, a laboratory fixed-bed gasifier installation was designed and built. Two sewage sludge (SS) feedstocks, taken from two typical Polish wastewater treatment systems, were analysed: SS1, from a mechanical-biological wastewater treatment system with anaerobic stabilization (fermentation) and high temperature drying; and (SS2) from a mechanical-biological-chemical wastewater treatment system with fermentation and low temperature drying. The gasification results show that greater oxygen content in sewage sludge has a strong influence on the properties of the produced gas. Increasing the air flow caused a decrease in the heating value of the produced gas. Higher hydrogen content in the sewage sludge (from SS1) affected the produced gas composition, which was characterized by high concentrations of combustible components. In the case of the SS1 gasification, ash, charcoal, and tar were produced as byproducts. In the case of SS2 gasification, only ash and tar were produced. SS1 and solid byproducts from its gasification (ash and charcoal) were characterized by lower toxicity in comparison to SS2. However, in all analysed cases, tar samples were toxic. PMID:24938297

  6. Entrainment of Upper Level Dry Air into Hurricane Earl

    Science.gov (United States)

    Guillory, Anthony R.; Jedlovee, Gary J.; Hood, Robbie E.; Atkinson, Robert J.; LaFontaine, Frank J.

    2000-01-01

    Hurricane Earl developed from a tropical wave that moved into the Gulf of Mexico, which triggered abundant convection. On 1 Sept. 1998, the wave was upgraded directly to a tropical storm. Earl reached hurricane status the next morning. The system moved erratically as it interacted with an upper level short wave trough rotating around a long wave trough to the northeast. The storm made landfall near 0600 UTC on 3 September near Panama City, FL. During August and September 1998, NASA conducted the Third Convection and Moisture Experiment (CAMEX-3). It focused on studying the intensity, track, and impacts at landfall of hurricanes. On the afternoon of 2 September 1998, the NASA ER2 high-altitude aircraft flying at 65,000 feet in tandem with the NASA DC-8 flying at 35,000 feet flew over and through, respectively, the eastern rainbands of Earl near the Florida Panhandle as the storm neared landfall in the region. Two approaches to studying Earl are undertaken here: first, an examination of the source and height of the dry air region using GOES-8 water vapor data and, second, a look into the impact of the dry air entrainment on the system using aircraft remote sensing data.

  7. Effect of green roofs on air temperature; measurement study of well-watered and dry conditions

    Science.gov (United States)

    Solcerova, Anna; van de Ven, Frans; Wang, Mengyu; van de Giesen, Nick

    2016-04-01

    Rapid urbanization and increasing number and duration of heat waves poses a need for understanding urban climate and ways to mitigate extremely high temperatures. One of repeatedly suggested and often investigated methods to moderate the so called urban heat island are green roofs. This study investigates several extensive green roofs in Utrecht (NL) and their effect on air temperature right above the roof surface. Air temperature was measured 15 and 30 cm above the roof surface and also in the substrate. We show that under normal condition is air above green roof, compared to white gravel roof, colder at night and warmer during day. This suggest that green roofs might help decrease air temperatures at night, when the urban heat island is strongest, but possibly contribute to high temperatures during daytime. We also measured situation when the green roofs wilted and dried out. Under such conditions green roof exhibits more similar behavior to conventional white gravel roof. Interestingly, pattern of soil temperature remains almost the same for both dry and well-prospering green roof, colder during day and warmer at night. As such, green roof works as a buffer of diurnal temperature changes.

  8. Experimental Study on Hot-air Drying Process Parameters Optimization of Chinese Jujubes

    OpenAIRE

    Xiao Kang-Yi; Chuan Feng-Li; Shu Gang-Li; He Lei Cui; Wen Fu-Wu

    2013-01-01

    In this study, the drying characteristics of jujubes conducted in a convective dryer were investigated under different air temperatures, air velocities, specific surface areas and densities of arrangement which conducted in a convective dryer. Furthermore, an orthogonal experiment was developed under different air temperatures, air velocities, specific surface areas and densities of arrangement. Such a reduction on drying rate was observed by the drying process. ...

  9. Low Temperature Drying With Air Dehumidified by Zeolite for Food Products: Energy Efficiency Aspect Analysis

    OpenAIRE

    M. Djaeni; Asselt, van, R.; Bartels, P.V.; Sanders, J. P. M.; Straten, van, FE; Boxtel, van, C.

    2011-01-01

    Developments in low temperature drying of food products are still an interesting issue; especially with respect to the energy efficiency. This research studies the energy efficiency that can be achieved by a dryer using air which is dehumidified by zeolite. Experimental results are fitted to a dynamic model to find important variables for the drying operation. The results show that ambient air temperature as well as the ratio between air flow for drying and air flow for regeneration, affect t...

  10. Dry heat effects on survival of indigenous soil particle microflora and particle viability studies of Kennedy Space Center soil

    Science.gov (United States)

    Ruschmeyer, O. R.; Pflug, I. J.; Gove, R.; Heisserer, Y.

    1975-01-01

    Research efforts were concentrated on attempts to obtain data concerning the dry heat resistance of particle microflora in Kennedy Space Center soil samples. The in situ dry heat resistance profiles at selected temperatures for the aggregate microflora on soil particles of certain size ranges were determined. Viability profiles of older soil samples were compared with more recently stored soil samples. The effect of increased particle numbers on viability profiles after dry heat treatment was investigated. These soil particle viability data for various temperatures and times provide information on the soil microflora response to heat treatment and are useful in making selections for spacecraft sterilization cycles.

  11. The role of soil air composition for noble gas tracer applications in tropical groundwater

    Science.gov (United States)

    Mayer, Simon; Jenner, Florian; Aeschbach, Werner; Weissbach, Therese; Peregovich, Bernhard; Machado, Carlos

    2016-04-01

    Dissolved noble gases (NGs) in groundwater provide a well-established tool for paleo temperature reconstruction. However, reliable noble gas temperature (NGT) determination needs appropriate assumptions or rather an exact knowledge of soil air composition. Deviations of soil air NG partial pressures from atmospheric values have already been found in mid latitudes during summer time as a consequence of subsurface oxygen depletion. This effect depends on ambient temperature and humidity and is thus expected to be especially strong in humid tropical soils, which was not investigated so far. We therefore studied NGs in soil air and shallow groundwater near Santarém (Pará, Brazil) at the end of the rainy and dry seasons, respectively. Soil air data confirms a correlation between NG partial pressures, the sum value of O2+CO2 and soil moisture contents. During the rainy season, we find significant NG enhancements in soil air by up to 7% with respect to the atmosphere. This is twice as much as observed during the dry season. Groundwater samples show neon excess values between 15% and 120%. Nearly all wells show no seasonal variations of excess air, even though the local river level seasonally fluctuates by about 8 m. Assuming atmospheric NG contents in soil air, fitted NGTs underestimate the measured groundwater temperature by about 1-2° C. However, including enhanced soil air NG contents as observed during the rainy season, resulting NGTs are in good agreement with local groundwater temperatures. Our presented data allows for a better understanding of subsurface NG variations. This is essential with regard to NG tracer applications in humid tropical areas, for which reliable paleoclimate data is of major importance for modern climate research.

  12. Vapor Flow Resistance of Dry Soil Layer to Soil Water Evaporation in Arid Environment: An Overview

    OpenAIRE

    Xixi Wang

    2015-01-01

    Evaporation from bare sandy soils is the core component of the hydrologic cycle in arid environments, where vertical water movement dominates. Although extensive measurement and modeling studies have been conducted and reported in existing literature, the physics of dry soil and its function in evaporation is still a challenging topic with significant remaining issues. Thus, an overview of the previous findings will be very beneficial for identifying further research needs that aim to advance...

  13. A revised parameterization for gaseous dry deposition in air-quality models

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2003-01-01

    Full Text Available A parameterization scheme for calculating gaseous dry deposition velocities in air-quality models is revised based on recent study results on non-stomatal uptake of O3 and SO2 over 5 different vegetation types. Non-stomatal resistance, which includes in-canopy aerodynamic, soil and cuticle resistances, for SO2 and O3 is parameterized as a function of friction velocity, relative humidity, leaf area index, and canopy wetness. Non-stomatal resistance for other chemical species is scaled to those of SO2 and O3 based on their chemical and physical characteristics. Stomatal resistance is calculated using a two-big-leaf stomatal resistance sub-model for all gaseous species of interest. The improvements in the present model compared to its earlier version include a newly developed non-stomatal resistance formulation, a realistic treatment of cuticle and ground resistance in winter, and the handling of seasonally-dependent input parameters. Model evaluation shows that the revised parameterization can provide more realistic deposition velocities for both O3 and SO2, especially for wet canopies. Example model output shows that the parameterization provides reasonable estimates of dry deposition velocities for different gaseous species, land types and diurnal and seasonal variations. Maximum deposition velocities from model output are close to reported measurement values for different land types. The current parameterization can be easily adopted into different air-quality models that require inclusion of dry deposition processes.

  14. Reduced heat stress in offices in the tropics using solar powered drying of the supply air

    DEFF Research Database (Denmark)

    Gunnarsen, Lars; Santos, A M B

    2002-01-01

    Many solutions to indoor climate problems known from developed countries may have prohibitive installation and running costs in developing countries. The purpose was to develop a low-cost solution to heat stress in a hot and humid environment based on solar powered drying of supply air. Dry supply...... air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different...... content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1 degree C. The solar-powered system for supplying dry air...

  15. Tritium release experiment in France results concerning HT/HTO conversion in the air and soil

    International Nuclear Information System (INIS)

    A controlled release of 256 TBq of pure dry tritium through a 40-m high stack was performed in France, on October 15, 1986. Air measurements were assigned to the Health Physics Division (SPR) from the Centre of Bruyeres-le-Chatel and soil measurements in particular for deposition velocity and reemission rate, to the Division for Studies and Research on the Environment (SERE) of the Institute of Protection and Nuclear Safety (IPSN). The main conclusions were: concordance between code predictions and air measurements; HTO increase in the air originating from soil effects; HT deposition velocity: 1 → 5 E-4 ms/sup -1/, reemission rate: 5 % per hour

  16. A proposed compressed air drying method using pressurized liquid desiccant and experimental verification

    International Nuclear Information System (INIS)

    Highlights: • A novel compressed air drying method using pressurized liquid desiccant was proposed. • Experiments verified the method and get compressed air with the humidity of 0.9 g/kg. • Energy efficiency was analyzed to show the energy saving potential of the new method. - Abstract: A novel compressed air drying method using pressurized liquid desiccant is proposed in this paper. The compressed air drying system is consisted of a compressed air module, a pressurized liquid desiccant dehumidifier, a liquid desiccant regenerator working in an atmospheric pressure, and other auxiliary components. An experimental apparatus of the pressurized liquid desiccant dehumidifier associated with a compressed air module is established to verify the proposed air drying method experimentally. The results show that, under the pressure of 0.5 MPa, the moisture content in the outlet air can reach 0.9 g/kg. The moisture content of the outlet air reaches 1.4 g/kg under the pressure of 0.3 MPa, and the power consumption of the drying system is 6.17 kJ/g, which is 0.69 kJ/g and 10.1% lower than the conventional compressed air cooling drying system. The dehumidification efficiency is around 0.90, indicating the sufficiently mass transfer between compressed air and solution in pressurized dehumidifier. Besides, the proposed compressed air drying system can use the low-grade heat from the air compressor to regenerate the diluted desiccant solution. The novel air drying method is verified to offer very dry air for industrial application, and shows significant energy saving potential compared with the conventional compressed air cooling drying system

  17. Tunneling behavior of the formosan subterranean termite (isoptera: rhinotermitadae) in dry soil

    Science.gov (United States)

    This study examines the effect of dry soil on tunnel construction by the Formosan subterranean termite, Cptotermes formosanus. Termites did not construct tunnels in dry soil in any of the treatments. Termites only constructed tunnels in moist areas in treatments where the soil was partially moistene...

  18. Transcriptome data - Air-drying stress - DGBY | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available [ Credits ] BLAST Search Image Search Home About Archive Update History Contact us DGBY Tran...scriptome data - Air-drying stress Data detail Data name Transcriptome data - Air-drying stress Des...suggested that the genes involved in protein folding were transiently upregulated at early stages, and that ... License Update History of This Database Site Policy | Contact Us Transcriptome data - Air-drying stress - DGBY | LSDB Archive ...

  19. OPTIMIZATION OF MICROWAVE AND AIR DRYING CONDITIONS OF QUINCE (CYDONIA OBLONGA, MILLER) USING RESPONSE SURFACE METHODOLOGY

    OpenAIRE

    Cem Baltacioglu

    2015-01-01

    Effects of slice thickness of quince (Cydonia oblonga Miller) , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i) for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity) and 285 W and 6.85 mm thick (maximum total phenolic content), and ii) for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activit...

  20. Hot air injection for removal of dense, non-aqueous-phase liquid contaminants from low-permeability soils

    Energy Technology Data Exchange (ETDEWEB)

    Payne, F.C.

    1996-08-01

    The performance of soil vapor extraction systems for the recovery of volatile and semi-volatile organic compounds is potentially enhanced by the injection of heated air to increase soil temperatures. The soil temperature increase is expected to improve soil vapor extraction (SVE) performance by increasing target compound vapor pressures and by increasing soil permeability through drying. The vapor pressure increase due to temperature rise relieves the vapor pressure limit on the feasibility of soil vapor extraction. However, the system still requires an air flow through the soil system to deliver heat and to recover mobilized contaminants. Although the soil permeability can be increased through drying, very low permeability soils and low permeability soils adjacent to high permeability air flow pathways will be treated slowly, if at all. AR thermal enhancement methods face this limitation. Heated air injection offers advantages relative to other thermal techniques, including low capital and operation costs. Heated air injection is at a disadvantage relative to other thermal techniques due to the low heat capacity of air. To be effective, heated air injection requires that higher air flows be established than for steam injection or radio frequency heating. Heated air injection is not economically feasible for the stratified soil system developed as a standard test for this document. This is due to the inability to restrict heated air flow to the clay stratum when a low-resistance air flow pathway is available in the adjoining sand. However, the technology should be especially attractive, both technically and economically, for low-volatile contaminant recovery from relatively homogeneous soil formations. 16 refs., 2 tabs.

  1. Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil

    International Nuclear Information System (INIS)

    Highlights: → The effects of soil physical properties on gas transport parameters were investigated. → Higher values of Dp and ka exhibited in the '+gravel' than the '-gravel' fraction at same soil-air content (ε). → Recent power law models for Dp (WLR) and ka (RPL) were modified. → Model parameters were linearly related to easily measurable dry bulk density (ρb). - Abstract: Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, ρb, and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (Dp/Do, ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting ρb values ranging from 1.40 to 2.10 g cm-3. Results showed that Dp and ka values for the '+gravel' fraction (p and ka was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity Dp/Df, the ratio of measured Dp to Dp in total porosity (f), (ii) for air permeability ka/ka,pF4.1, the ratio of measured ka to ka at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content (ε) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for Dp(ε/f) and ka(ε/f) models were developed based on a single parameter (water blockage factor M for Dp and P for ka). The water blockage factors, M and P, were found to be linearly correlated to ρb values, and the effects of dry bulk density on Dp and ka for both '+gravel' and '-gravel' fractions were well accounted for by the new models.

  2. How does mid-tropospheric dry air affect the evolution of supercellular convection?

    Science.gov (United States)

    Honda, Takumi; Kawano, Tetsuya

    2015-04-01

    To investigate the influence of mid-tropospheric dry air on the evolution of supercell storms, idealized numerical experiments with several moisture profiles were performed. In an environment with (without) a mid-level dry layer, supercellular convection decays immediately (persists for a long period). A set of trajectory analyses revealed that two suppression processes contribute to the convection decay in the environment with the mid-tropospheric dry layer. One is the entrainment process within the mid-tropospheric dry layer, and the other is the dry-air penetration process. In the latter process, dry air penetrates into the low-level updraft region, so that the supply of warm, moist air for convection is reduced. Neither of the processes contributes effectively in an environment with a dry layer located at a higher altitude. The dependence of the results on the environmental shear profile, evaporation rate, and the amount of convective available potential energy (CAPE) was also examined by additional experiments.

  3. Redistributed water by saprotrophic fungi triggers carbon mineralization in dry soils

    Science.gov (United States)

    Guhr, Alexander; Borken, Werner; Matzner, Egbert

    2015-04-01

    Summer droughts are common in temperate forests and especially the upper soil horizons experience soil drought. Drought events can be accompanied by negative effects for forest ecosystems but many plants can reduce drought stress by hydraulic redistribution (HR). Similar processes were recently described for ectomycorrhizal networks but no information is available for mycelia networks of saprotrophic fungi. They strongly contribute to belowground nutrient cycling, C and N mineralization. We hypothesize that redistributed water by saprotrophic fungi triggers mineralization of organic matter in soils under drought conditions. The impact of HR by saprotrophic fungi on mineralization was determined using mesocosms comprising two chambers, separated by a 2 mm air gap to prevent bulk flow of water. After inoculation with fungal cultures and a growth phase, both chambers were desiccated. Subsequently, only chamber I was rewetted while chamber II was treated with 13C labelled plant material. CO2 samples were collected over 7 days after rewetting and analyzed for stable isotope ratio. In addition, enzymatic activity of chitinases and cellobiohydrolases in chamber II was determined after 7 days using the soil zymographie method with fluorogenic 4-Methylumbelliferyl-substrates. A negative control was provided by mesocosms in which hyphal connections between the chambers were severed before rewetting. Intact fungal connections between the chambers led to a strong increase in volumetric water content in chamber II after rewetting of chamber I and the CO2 had a higher enrichment in 13C than in the control mescosms with severed connections. Enrichment started 48 h after rewetting and continued for the rest of the experiment. This resulted in a more than two fold higher total carbon mineralization after 7 days in chamber II of mesocosms with intact hyphal connections. In addition, enzyme activities were also strongly increased compared to controls. In conclusion, mycelia networks

  4. The Sappanwood Extract Drying With Carrier Agent Under Air Dehumidification

    OpenAIRE

    Mohamad Djaeni; Meilya Suzan Triyastuti; Febiani Utari; Arianti Nuur Annisa; Dewi Ayu Novita

    2016-01-01

    The sappanwood extract enriched by brazilin can be used for natural colouring agent in food and beverages. The extract is produced in form of dry powder for consummer convenience as well as prolonging storage life. Currently, the sappanwood extract drying still deals with the product sticky that inhibit water transport in drying. As a result, the drying process needs long time to get moisture content below 10%. The extract drying with carrier agent is an option to break the product sticky and...

  5. Optimization of microwave-assisted hot air drying conditions of okra using response surface methodology.

    Science.gov (United States)

    Kumar, Deepak; Prasad, Suresh; Murthy, Ganti S

    2014-02-01

    Okra (Abelmoschus esculentus) was dried to a moisture level of 0.1 g water/g dry matter using a microwave-assisted hot air dryer. Response surface methodology was used to optimize the drying conditions based on specific energy consumption and quality of dried okra. The drying experiments were performed using a central composite rotatable design for three variables: air temperature (40-70 °C), air velocity (1-2 m/s) and microwave power level (0.5-2.5 W/g). The quality of dried okra was determined in terms of color change, rehydration ratio and hardness of texture. A second-order polynomial model was well fitted to all responses and high R(2) values (>0.8) were observed in all cases. The color change of dried okra was found higher at high microwave power and air temperatures. Rehydration properties were better for okra samples dried at higher microwave power levels. Specific energy consumption decreased with increase in microwave power due to decrease in drying time. The drying conditions of 1.51 m/s air velocity, 52.09 °C air temperature and 2.41 W/g microwave power were found optimum for product quality and minimum energy consumption for microwave-convective drying of okra. PMID:24493879

  6. Effects of dry bulk density and particle size fraction on gas transport parameters in variably saturated landfill cover soil.

    Science.gov (United States)

    Wickramarachchi, Praneeth; Kawamoto, Ken; Hamamoto, Shoichiro; Nagamori, Masanao; Moldrup, Per; Komatsu, Toshiko

    2011-12-01

    Landfill sites are emerging in climate change scenarios as a significant source of greenhouse gases. The compacted final soil cover at landfill sites plays a vital role for the emission, fate and transport of landfill gases. This study investigated the effects of dry bulk density, ρ(b), and particle size fraction on the main soil-gas transport parameters - soil-gas diffusivity (D(p)/D(o), ratio of gas diffusion coefficients in soil and free air) and air permeability (k(a)) - under variably-saturated moisture conditions. Soil samples were prepared by three different compaction methods (Standard and Modified Proctor compaction, and hand compaction) with resulting ρ(b) values ranging from 1.40 to 2.10 g cm(-3). Results showed that D(p) and k(a) values for the '+gravel' fraction (soil-air content (ε), likely due to enhanced gas diffusion and advection through less tortuous, large-pore networks. The effect of dry bulk density on D(p) and k(a) was most pronounced for the '+gravel' fraction. Normalized ratios were introduced for all soil-gas parameters: (i) for gas diffusivity D(p)/D(f), the ratio of measured D(p) to D(p) in total porosity (f), (ii) for air permeability k(a)/k(a)(,pF4.1), the ratio of measured k(a) to k(a) at 1235 kPa matric potential (=pF 4.1), and (iii) for soil-air content, the ratio of soil-air content (ε) to total porosity (f) (air saturation). Based on the normalized parameters, predictive power-law models for D(p)(ε/f) and k(a)(ε/f) models were developed based on a single parameter (water blockage factor M for D(p) and P for k(a)). The water blockage factors, M and P, were found to be linearly correlated to ρ(b) values, and the effects of dry bulk density on D(p) and k(a) for both '+gravel' and '-gravel' fractions were well accounted for by the new models. PMID:21813272

  7. Seismic Soil-Structure Interaction Analysis of a Consolidated Dry Storage Module for CANDU Spent Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Young Gon; Yoon, Jeong Hyoun; Cho, Chun Hyung; Lee, Heung Young [Korea Hydro and Nuclear Power Co., Ltd., Taejon (Korea, Republic of); Choi, Kyu Sup; Jeong, In Su; Kim, Jong Soo [KONES Co., Seoul (Korea, Republic of)

    2005-07-01

    The MACSTOR/KN-400 module has been developed as an effective alternative to the existing stand alone concrete canister for dry storage of CANDU spent fuel. The structure is a concrete monolith of 21.67 m long and 12.66 m wide and has a height equal to 7.518 m including the bottom slab. Inside of the concrete module are built 40 storage cylinders accommodating ten 60- bundle dry storage baskets, which are suspended from the top slab and eventually constrained at 10 cm above the bottom slab with horizontal seismic restraints. The main cooling process of the MACSTOR/KN-400 module is by air convection through air inlets and outlets. The civil design parameters, with respect to meteorological and seismic loads applied to the module are identical to those specified for the Wolsung CANDU 3 and 4 plants except for local geologic characteristics. As per USNRC SRP Section 3.7.2 and current US practices, Soil-Structure Interaction (SSI) effect shall be considered for all structures not supported by a rock or rock-like soil foundation materials. An SSI is a very complicated phenomenon of the structure coupled with the soil medium that is usually semi-infinite in extent and highly nonlinear in its behavior. And the effect of the SSI is noticeable especially for stiff and massive structures resting on relatively soft ground. Thus the SSI effect has to be considered in the seismic design of MACSTOR/KN-400 module resting on soil medium. The scope of the this paper is to carry out a seismic SSI analysis of the MACSTOR/KN-400 module, in order to show how much the SSI gives an effect on the structural responses by comparing with the fixed-base analysis.

  8. A minimal probabilistic model for soil moisture in seasonally dry climates

    Science.gov (United States)

    Dralle, David N.; Thompson, Sally E.

    2016-02-01

    In seasonally dry climates, a distinct rainy season is followed by a pronounced dry season during which rainfall often makes a negligible contribution to soil moisture. Using stochastic analytical models of soil moisture to represent the effects of this seasonal change has been hindered by the need to mathematically represent the stochastic influence of wet season climate on dry season soil water dynamics. This study presents a simple process-based stochastic model for soil moisture dynamics, which explicitly models interseasonal transient dynamics while accounting for carry over soil moisture storage between the wet and dry seasons, and allows a derivation of an analytical expression for the dry season mean first passage time below a soil moisture threshold. Such crossing times pose controls on both vegetation productivity and water stress during dry summers. The new model, along with an existing model that incorporates nonzero dry season rainfall but not variability in the soil moisture condition at the start of the dry season, are tested against data from the Tonzi Ranch Ameriflux site. Both models predict first passage times well for high soil moisture thresholds, but the new model improves prediction at lower thresholds. The annual soil moisture probability distribution function (PDF) from the new model also compares well with observations.

  9. Phenome data - Air-drying stress - DGBY | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available functions and in connection with vacuolar H + -ATPase, which plays a role in vacuolar acidification. To dete...rmine the role of vacuolar acidification in air-drying stress tolerance, we monit...ored intracellular pH. The results showed that intracellular acidification was induced during air-drying and that this acidification

  10. Effect of mechanical drying air conditions on quality of turmeric powder

    OpenAIRE

    Singh, Gursewak; Arora, Sadhna; Kumar, Satish

    2010-01-01

    Mother and finger rhizomes ‘PCT-8’ (‘Suvarna’) variety of turmeric (Curcuma longa L) were boiled separately in open pan for 45 min at 100°C. The rhizomes were then dried using tray drier at air temperatures of 45, 50, 55, 60 and 65°C and drying air velocities of 1, 2 and 3 m/sec. The rhizomes were dried to ∼10 % (wb) moisture content. The dried rhizomes were polished manually and powdered. The volume of fresh and dried turmeric was determined and shrinkage ratio calculated. The colour of fres...

  11. OPTIMIZATION OF MICROWAVE AND AIR DRYING CONDITIONS OF QUINCE (CYDONIA OBLONGA, MILLER USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    Cem Baltacioglu

    2015-03-01

    Full Text Available Effects of slice thickness of quince (Cydonia oblonga Miller , microwave incident power and air drying temperature on antioxidant activity and total phenolic content of quince were investigated during drying in microwave and air drying. Optimum conditions were found to be: i for microwave drying, 285 W and 4.14 mm thick (maximum antioxidant activity and 285 W and 6.85 mm thick (maximum total phenolic content, and ii for air drying, 75 ºC and 1.2 mm thick (both maximum antioxidant activity and total phenolic content. Drying conditions were optimized by using the response surface methodology. 13 experiments were carried out considering incident microwave powers from 285 to 795 W, air temperature from 46 to 74 ºC and slice thickness from 1.2 to 6.8 mm.

  12. High Temperature Convective Drying of a Packed Bed with Humid Air at Different Humidities

    Directory of Open Access Journals (Sweden)

    J. Sghaier

    2009-01-01

    Full Text Available Problem statement: Drying a packed bed of porous particle at high temperature with varying humidity of hot air is an attractive process. Despite, many researches on experimental and simulation on a fixed bed drying at low and average temperature are proposed. Few studies showed drying at high temperature with humid air or using superheated steam. The latest is compared to dry air. Approach: In this study, we show an experimental and numerical study of humid air drying of a fixed bed of moist porous alumina particles. The air velocity, the air temperature and the vapor pressure were varied from 1.7-2.3 m.sec-1, 120-160°C and 0.1-0.65 bar, respectively and the experiments were performed at atmospheric pressure. Then a mathematical describing heat and mass transfer during drying is developed. This model is based on the averaging volume approach using two scale changes. Results: From the experimental works, the solid temperature and the bed moisture content have been presented at different drying conditions. The previous results show that an increase in humidity leads to an increase of the wet bulb temperature and a decrease in the drying time. At the same drying temperature, the variation in the gas velocity affects also the drying time. In addition, we note that the drying time increases if the bed depth increases. The predicted results deduced from the developed model were compared with the experiment. Conclusion: The experimental and predicted results obtained from this study describing drying of a packed bed illustrate clearly the effect of the air humidity on the drying kinetics.

  13. Air-soil exchange of PCBs: levels and temporal variations at two sites in Turkey.

    Science.gov (United States)

    Yolsal, Didem; Salihoglu, Güray; Tasdemir, Yücel

    2014-03-01

    Seasonal distribution of polychlorinated biphenyls (PCBs) at the air-soil intersection was determined for two regions: one with urban characteristics where traffic is dense (BUTAL) and the other representing the coastal zone (Mudanya). Fifty-one air and soil samples were simultaneously collected. Total PCB (Σ82 PCB) levels in the soil samples collected during a 1-year period ranged between 105 and 7,060 pg/g dry matter (dm) (BUTAL) and 110 and 2,320 pg/g dm (Mudanya). Total PCB levels in the gaseous phase were measured to be between 100 and 910 pg/m(3) (BUTAL) and 75 and 1,025 pg/m(3) (Mudanya). Variations in the concentrations were observed depending on the season. Though the PCB concentrations measured in the atmospheres of both regions in the summer months were high, they were found to be lower in winter. However, while soil PCB levels were measured to be high at BUTAL during summer months, they were found to be high during winter months in Mudanya. The direction and amount of the PCB movement were determined by calculating the gaseous phase change fluxes at air-soil intersection. While a general PCB movement from soil to air was found for BUTAL, the PCB movement from air to soil was calculated for the Mudanya region in most of the sampling events. During the warmer seasons PCB movement towards the atmosphere was observed due to evaporation from the soil. With decreases in the temperature, both decreases in the number of PCB congeners occurring in the air and a change in the direction of some congeners were observed, possibly caused by deposition from the atmosphere to the soil. 3-CB and 4-CB congeners were found to be dominant in the atmosphere, and 4-, 5-, and 6-CBs were found to dominate in the surface soils. PMID:24293299

  14. Optimization of Microwave-Osmotic Pretreatment of Apples with Subsequent Air-Drying for Preparing High-Quality Dried Product

    Directory of Open Access Journals (Sweden)

    Elham Azarpazhooh

    2011-01-01

    Full Text Available Prepared apple (Red Gala cylinders were subjected to microwave-osmotic dehydration treatment under continuous flow medium spray (MWODS conditions and then air-dried to a final 20% moisture content. The dried samples were evaluated for color and textural properties, and rehydration capacity. The MWODS pretreatments were based on a central composite rotatable design and a response surface methodology using five levels of sucrose concentration, temperature, and contact time at a constant flow rate of 2800 mL/min. The air-drying was carried out at 60°C, 15±1% relative humidity, and 0.64±0.02 m/s air velocity. The results were compared to untreated air-dried (AD (worst-case scenario and freeze-dried (FD (best-case scenario apples without the MWODS treatment. Color properties were affected regardless of the type of treatment. Conventional AD apples were darker in color, whereas MWODS-treated samples were lighter with higher L∗ and b∗ values, higher Hue and Chroma values but lower a∗ value and ΔE. Further the color parameters of MWODS-treated samples were closer or equal to the FD apples. The texture properties were also affected by the osmotic variables with MWODS treatment resulting in softer and chewier products. The AD samples were hard, and FD apples were brittle.

  15. The inlfuence of soil drying- and tillage-induced penetration resistance on maize root growth in a clayey soil

    Institute of Scientific and Technical Information of China (English)

    LIN Li-rong; HE Yang-bo; CHEN Jia-zhou

    2016-01-01

    Soil drying may induce a number of stresses on crops. This paper investigated maize (Zea maysL.) root growth as affected by drought and soil penetration resistance (PR), which was caused by soil drying and tilage in a clayey red soil. Com-pared with conventional tilage (C) and deep tilage (D), soil compaction (P) and no-til (N) signiifcantly increased soil PR in the 0–15 cm layer. The PR increased dramaticaly as the soil drying increased, particularly in soil with a high bulk density. Increased soil PR reduced the maize root mass density distribution not only in the vertical proifle (0–20 cm) but also in the horizontal layer at the same distance (0–5, 5–10, 10–15 cm) from the maize plant. With an increase in soil PR in pots, the maize root length, root surface area and root volume signiifcantly decreased. Speciifcaly, the maize root length declined exponentialy from 309 to 64 cm per plant with an increase in soil PR from 491 to 3370 kPa; the roots almost stopped elon-gating when the soil PR was larger than 2200 kPa. It appeared that ifne roots (<2.5 mm in diameter) thickened when the soil PR increased, resulting in a larger average root diameter. The average root diameter increased linearly with soil PR, regardless of soil irrigation or drought. The results suggest that differences in soil PR caused by soil drying is most likely responsible for inconsistent root responses to water stress in different soils.

  16. Oxidation behaviour of U2Ti alloy in dry air

    International Nuclear Information System (INIS)

    U2Ti alloy is being considered as promising storage material for storage of hydrogen isotopes. However, the absorption capacity of this reactive alloy can be affected due to presence of oxygen in the process gas. Hence, it is necessary to know the kinetic of this alloy in presence of oxygen. In this study, U2Ti alloy was prepared by arc melting method followed by vacuum annealing. The alloy was characterized by XRD, SEM and EDX methods. The isothermal oxidation behaviour of U2Ti alloy was investigated in the temperature range of 548-623 K in dry air for 24 hours by using thermo gravimetric technique. The oxidation curves are shown. The oxidation curves were analysed using the rate equation: (Δm/a)n = kt, where, (Δm/a) is the mass gain per unit area, n is the power exponent, k is the rate constant and t is time in (seconds). Analysis of the results shows that the oxidation reaction follows linear rate law (n ~ 1). Using the linear rate law, the rate constant (k) of oxidation reaction was evaluated at each temperature in the range 548-623 K. The variation of (ln k) with reciprocal temperature is shown. The activation energy of this oxidation reaction in the temperature range 548-623 K was calculated using the Arrhenius equation and found to be 76 kJ/mol. The XRD analysis of the oxidation products was found to be U3O8 and TiO2. (author)

  17. Dynamics of air gap formation around roots with changing soil water content.

    Science.gov (United States)

    Vetterlein, D.; Carminati, A.; Weller, U.; Oswald, S.; Vogel, H.-J.

    2009-04-01

    Most models regarding uptake of water and nutrients from soil assume intimate contact between roots and soil. However, it is known for a long time that roots may shrink under drought conditions. Due to the opaque nature of soil this process could not be observed in situ until recently. Combining tomography of the entire sample (field of view of 16 x 16 cm, pixel side 0.32 mm) with local tomography of the soil region around roots (field of view of 5 x 5 cm, pixel side 0.09 mm), the high spatial resolution required to image root shrinkage and formation of air-filled gaps around roots could be achieved. Applying this technique and combining it with microtensiometer measurements, measurements of plant gas exchange and microscopic assessment of root anatomy, a more detailed study was conducted to elucidate at which soil matric potential roots start to shrink in a sandy soil and which are the consequences for plant water relations. For Lupinus albus grown in a sandy soil tomography of the entire root system and of the interface between taproot and soil was conducted from day 11 to day 31 covering two drying cycles. Soil matric potential decreased from -36 hPa at day 11 after planting to -72, -251, -429 hPa, on day 17, 19, 20 after planting. On day 20 an air gap started to occur around the tap root and extended further on day 21 with matric potential below -429 hPa (equivalent to 5 v/v % soil moisture). From day 11 to day 21 stomatal conductivity decreased from 467 to 84 mmol m-2 s-1, likewise transpiration rate decreased and plants showed strong wilting symptoms on day 21. Plants were watered by capillary rise on day 21 and recovered completely within a day with stomatal conductivity increasing to 647 mmol m-2 s-1. During a second drying cycle, which was shorter as plants continuously increased in size, air gap formed again at the same matric potential. Plant stomatal conductance and transpiration decreased in a similar fashion with decreasing matric potential and

  18. Fruits & Vegetables Drying Combining Hot Air, DIC Technology and Microwaves

    Czech Academy of Sciences Publication Activity Database

    Al Haddad, M.; Mounir, S.; Sobolík, Václav; Allaf, K.

    Hong Kong: World Scientific, 2008 - (Chen, G.), s. 1064-1069 ISBN 978-981-277-194-0. [Asia-Pacific Drying Conference /5./. Hong Kong (CN), 13.08.2007-15.08.2007] Institutional research plan: CEZ:AV0Z40720504 Keywords : drying * dic technology * microwaves Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  19. Air and Soil Water Vapour Density Variations in Akungba Akoko

    Directory of Open Access Journals (Sweden)

    Afolabi O.M

    2015-10-01

    Full Text Available – A temperature and humidity measuring equipment constructed with Silicon lab Si7015 integrated circuit sensor was used to monitor temperature and humidity, compute water saturation and vapour densities for air and soil and to interpret three days variations in Akungba Akoko. The sensors were inserted 5 cm into the soil and 2m away in the troposphere. Two hour records of both parameters were taken from 9 am to 5 pm for 3 days. Air and soil water saturation and vapour density data were computed from the 2 measured parameters by using the ITU-2003 formula. Interpretations of resulting curves showed that increase in vapour density in soil is more than that of air during rainfall and this increase with temperature. The average soil water saturation data and vapour density are also higher in soil. It is suggested that the soil water vapour density and water saturation interpretation should be done for areas with landslides and pollution tendencies

  20. Effects of Super Absorbent Resin on Soil Characteristics in Dry-land Wheat

    Directory of Open Access Journals (Sweden)

    Zhanli Hu

    2014-04-01

    Full Text Available In order to improve the water use efficiency of soil water in dry-land wheat, we carried out a research with a pot experiment. The pot experiment was conducted with the material of Jimai 22 to study the effects of different application amounts of Super Absorbent Resin (SAR on soil characteristics in dry-land wheat. The results indicated that the application of SAR could maintain the soil water content and decrease the soil water evapotranspiration in dry-land wheat. Among the five treatments, the application of T2 was the most reasonable to maintain the soil water content for dry-land wheat. What’s more, it had some effect on soil aggregate structure and soil pH in dry-land wheat. It not only had a certain role in promoting the formation of soil aggregate structure, but also it could reduce soil pH in dry-land wheat and made the pH value decrease into the suitable range for crop growth.

  1. Mathematical modelling of thin layer hot air drying of carrot pomace

    OpenAIRE

    Kumar, Navneet; Sarkar, B. C.; Sharma, H. K.

    2011-01-01

    Thin layer carrot pomace drying characteristics were evaluated in a laboratory scale hot air forced convective dryer. The drying experiments were carried out at 60, 65, 70 & 75 °C and at an air velocity of 0.7 m/s. Mathematical models were tested to fit drying data of carrot pomace. The whole drying process of carrot pomace took place in a falling rate period except a very short accelerating period at the beginning. The average values of effective diffusivity ranged from 2.74 × 10−9 to 4.64 ×...

  2. Performance of Silica Gel in the Role of Residual Air Drying

    Science.gov (United States)

    Jan, Darrell L.; Hogan, John A.; Koss, Brian; Palmer, Gary H.; Richardson, Justine; Linggi, Paul

    2014-01-01

    Removal of carbon dioxide (CO2) is a necessary step in air revitalization and is often accomplished with sorbent materials. Since moisture competes with CO2 in sorbent materials, it is necessary to remove the water first. This is typically accomplished in two stages: bulk removal and residual drying. Silica gel is used as the bulk drying material in the Carbon Dioxide Removal Assembly (CDRA) in operation on ISS. There has been some speculation that silica gel may also be capable of serving as the residual drying material. This paper will describe test apparatus and procedures for determining the performance of silica gel in residual air drying.

  3. Effects of Composted and Thermally Dried Sewage Sludges on Soil and Soil Humic Acid Properties

    Institute of Scientific and Technical Information of China (English)

    J.M.FERN(A)NDEZ; N.SENESI; C.PLAZA; G.BRUNETTI; A.POLO

    2009-01-01

    The effect of annual additions of composted sewage sludge (CS) and thermally dried sewage sludge (TS) at 80 t ha-1 on soil chemical properties was investigated for three years in a field experiment under semiarid conditions.Humie acids (HAs) isolated by conventional procedures from CS,TS,and unamended (SO) and sludge amended soils were analysed for elemental (C,H,N,S and O) and acidic functional groups (carboxylic and phenolic) and by ultraviolet-visible,Fourier transform infrared and fluorescence spectroscopies.With respect to CS,TS had similar pH and total P and K contents,larger dry matter,total organic C,total N.and C/N ratio and smaller ash content and electrical conductivity.Amendment with both CS and TS induced a number of modifications in soil properties,including an increase of pH,electrical conductivity,total organic C,total N,and available P.The CS-HA had greater O,total acidity,carboxyl,and phenolic OH group contents and smaller C and H contents than TS-HA.The CS-HA and TS-HA had larger N and S contents,smaller C,O and acidic functional group contents,and lower aromatic polycondensation and humification degrees than SO-HA.Amended soil-HAs showed C,H,N and S contents larger than SO-HA,suggesting that sludge HAs were partially incorporated into soil HAs.These effects were more evident with increasing number of sludge applications.

  4. Drying effects on selenium and copper in 0.01M calcium chloride soil extractions

    NARCIS (Netherlands)

    Supriatin, Supriatin; Terrones, Cristian Adolfo; Bussink, Wim; Weng, Liping

    2015-01-01

    The study aimed to understand the effects of drying and rewetting the soils on soluble selenium (Se) and copper (Cu) concentrations in 0.01M CaCl2 soil extraction, and the mechanisms leading to these changes. Soluble Se and Cu concentrations were measured in the extractions of 58 soil

  5. Hot air drying of apple slices: dehydration characteristics and quality assessment

    Science.gov (United States)

    Beigi, Mohsen

    2015-08-01

    The main objectives of the present study were to investigate the drying characteristics and quality attributes of apple slices. The samples were dried at different air temperature levels (50, 60 and 70 °C) and a constant air velocity (1.5 m s-1). It was observed that the drying air temperature affected the dehydration rate significantly. The usefulness of eight different mathematical models to simulate the experimental drying curves was evaluated and the Midilli model provided the best simulation of the samples drying kinetics. The effective moisture diffusivity was determined to be 7.03 × 10-10, 8.48 × 10-10 and 1.08 × 10-9 m2 s-1 for drying air temperatures of 50, 60 and 70 °C, respectively. The shrinkage values of the dried samples at air temperatures of 50, 60 and 70 °C were 74.70, 82.35 and 80.78 %, respectively. The maximum value of rehydration ratio (4.527) and also the minimum value of ∆E (11.27) were obtained for the slices dried at 70 °C.

  6. Reduced heat stress in offices in the tropics using solar powered drying of the supply air

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsen, L. [By og Byg. Statens Byggeforskningsinstitut, Hoersholm (Denmark); Santos, A.M.B. [Univ. of the Philippines, Diliman (Philippines)

    2002-07-01

    Many solutions to indoor climate problems known from developed countries may have prohibitive installation and running costs in developing countries. The purpose was to develop a low-cost solution to heat stress in a hot and humid environment based on solar powered drying of supply air. Dry supply air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different combinations of temperature and humidity and led to Personal Units for Ventilation and Cooling (PUVAC) in six cubicles simulating office workplaces. A total of 123 heat acclimatized subjects were exposed 45 min in each of the cubicles. A model for the combined effect of operative temperature of room, moisture content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1deg C. The solar-powered system for supplying dry air is a low-cost alternative to traditional air conditioning in hot and humid regions. (au)

  7. Reduced heat stress in offices in the tropics using solar powered drying of the supply air.

    Science.gov (United States)

    Gunnarsen, L; Santos, A M B

    2002-12-01

    Many solutions to indoor climate problems known from developed countries may have prohibitive installation and running costs in developing countries. The purpose was to develop a low-cost solution to heat stress in a hot and humid environment based on solar powered drying of supply air. Dry supply air may facilitate personal cooling by increased evaporation of sweat. Heat acclimatized people with efficient sweating may in particular benefit from this cooling. A prototype solar powered supply system for dried-only air was made. Air from the system was mixed with room air, heated to six different combinations of temperature and humidity and led to Personal Units for Ventilation and Cooling (PUVAC) in six cubicles simulating office workplaces. A total of 123 heat acclimatized subjects were exposed 45 min in each of the cubicles. A model for the combined effect of operative temperature of room, moisture content of room air, temperature of supply air and moisture content of supply air was developed based on the experiments. Reduction of moisture content in the supply air by 1.6 g/kg had the same effect as lowering the operative temperature by 1 degree C. The solar-powered system for supplying dry air is a low-cost alternative to traditional air conditioning in hot and humid regions. PMID:12532757

  8. Drying/rewetting cycles of the soil under alternate partial root-zone drying irrigation reduce carbon and nitrogen retention in the soil-plant systems of potato

    DEFF Research Database (Denmark)

    Sun, Yanqi; Yan, Fei; Liu, Fulai

    2013-01-01

    Dry/wet cycles of soil may stimulate mineralization of soil organic carbon (C) and nitrogen (N) leading to increased N bioavailability to plants but potentially also increased C and N losses. We investigated the effects of partial root-zone drying (PRD) and deficit irrigation (DI) on C and N......-fertilization rate but were unaffected by the irrigation treatment. As compared with DI, PRD significantly decreased soil C and N contents, which could have been due to an enhanced soil organic C and N mineralization. PRD did not influence plant C content but significantly increased plant N content in relation to DI...... PRD treatment stimulated the mineralization of soil organic C and N leading to greater C and N losses; thus PRD might not be a sustainable irrigation practice in terms of C and N sequestration in the soil–plant systems....

  9. Industrial drying of wooden pallets - CFD analysis of air flow

    OpenAIRE

    Ghiaus, Adrian; Filios, Andronikos; Margaris, Dionissios; Tzempelikos, Dimitrios

    2013-01-01

    This paper presents the results of the airflow 2D numerical simulation inside an industrial unit designed for drying of wooden pallets. The airflow field profile was examined in different operation conditions by plotting velocity vector distribution, path lines and pressure contours for both loaded with the wooden pallets and unloaded drying room. The analysis of the obtained results shows the presence of stagnation zones between and above the pallet columns and recirculation regions in diffe...

  10. Study of 222Rn variations in the soil air

    International Nuclear Information System (INIS)

    A significant source of radon in the indoor atmosphere is represented by 222Rn in the soil air, ie., by the fraction of radon atoms produced by alpha decay of 226Ra in soil grains that escaped into soil pores. In the paper the results are presented of a three year monitoring of radon in soil air, using a 125 ml Lucas type scintillation cell. Radon concentration depth profiles in the soil in various seasons of the year were also measured, and saturated concentration of radon in soil air was found at a depth of about 2 m. Monthly variations in the radon concentration were observed over several months and the possible causes of the variations are discussed. Daily courses of radon concentration were also measured and the results are presented. (A.K.)

  11. Microbial responses of forest soil to moderate anthropogenic air pollution - a large scale field survey

    International Nuclear Information System (INIS)

    There is a need to introduce soil microbiological methods into long term ecological monitoring programs. For this purpose we studied the impact of moderate anthropogenic air pollution in polluted and less polluted area districts, forest site types Calluna (CT), Vaccinium (VT) and Myrtillus (MT) and the amount of organic matter, measured as carbon content on the soil respiration activity and the ATP content. The main sources of local air pollutants (SO2 and NOx) in the polluted area district were from the capital region and an oil refinery. Humus (F/H-layer) and the underlying 0 to 5 cm mineral soil samples were collected from 193 study plots located in the 5300 km2 study area. We found that the soil respiration rate in humus layer samples was lower in the polluted area district compared to the less polluted one (16.0 and 19.5μL CO2 h-1g-1 dw, respectively), but the difference occurred only in the dry, coarse-textured CT forest site type. The mineral soil respiration rate and the mineral soil and humus layer ATP content were not affected by the air pollution. Most of the variations of the biological variables were explained primarily by the soil carbon content, secondly by the forest site type and thirdly by the area division. 38 refs., 1 fig., 6 tabs

  12. Anti-Browning of Mushroom (Agaricus bisporus Slices by Glutathione during Hot Air Drying

    Directory of Open Access Journals (Sweden)

    Zhenqiang Xia

    2013-08-01

    Full Text Available Browning of mushroom tends to occur during hot air drying due to Poly Phenol Oxidase (PPO, while glutathione is known for its ability to inhibit the activity of PPO and browning. In this study, the efficacy of glutathione in inhibiting browning on mushroom slices was estimated. Browning of mushroom slices treated with glutathione was monitored during hot air drying. PPO activity in mushroom was inhibited by 98.2 with 0.08% glutathione. Compared with the control, mushroom slices treated with glutathione showed no browning during hot air drying. These results indicate that application of glutathione is a promising method of Anti-browning of mushroom by glutathione during hot air drying.

  13. Comparison of the effects of gamma radiation on hydrated and air dried rye grass seeds

    International Nuclear Information System (INIS)

    This is a comparative study of the effects of gamma radiation on the growth of hydrated and air dried seeds during the first weeks of primary growth. Four groups of seeds were used in the study: 1) hydrated sweet corn, 2) air dried sweet corn, 3) hydrated rye grass, and 4) air dried rye grass. Each group was then further subdivided and exposed to various levels of gamma radiation using a Cobalt-60 irradiator, except for the control samples of the four groups which received no radiation above background level. All seeds samples were then planted, allowed to grow for approximately 12 days, and harvested. Growth of both shoot and root of each seed was recorded for data analysis according to specific groups. Analyses of data from this study shows that the mean growth of air dried seeds when exposed to gamma radiation prior to planting

  14. Solar-Supplemented, Natural Air Drying of Shelled Corn: The Economic Limitations

    OpenAIRE

    Heid, Walter G. Jr; Aldis, David F.

    1981-01-01

    It is not economically feasible to supplement natural air drying of high-moisture shelled corn by adding heat (solar and otherwise). In some cases, that drying method speeds product deterioration. A simulatiton analysis of the west central Great Plains determined that benefits from adding solar heat to batch-in-bin and layer~in-bin grain drying. methods failed to offset the solar heat installation costs and product deterioration losses. Findings also suggest that high-speed, high temperature ...

  15. Mass transfer characteristics of bisporus mushroom ( Agaricus bisporus) slices during convective hot air drying

    Science.gov (United States)

    Ghanbarian, Davoud; Baraani Dastjerdi, Mojtaba; Torki-Harchegani, Mehdi

    2016-05-01

    An accurate understanding of moisture transfer parameters, including moisture diffusivity and moisture transfer coefficient, is essential for efficient mass transfer analysis and to design new dryers or improve existing drying equipments. The main objective of the present study was to carry out an experimental and theoretical investigation of mushroom slices drying and determine the mass transfer characteristics of the samples dried under different conditions. The mushroom slices with two thicknesses of 3 and 5 mm were dried at air temperatures of 40, 50 and 60 °C and air flow rates of 1 and 1.5 m s-1. The Dincer and Dost model was used to determine the moisture transfer parameters and predict the drying curves. It was observed that the entire drying process took place in the falling drying rate period. The obtained lag factor and Biot number indicated that the moisture transfer in the samples was controlled by both internal and external resistance. The effective moisture diffusivity and the moisture transfer coefficient increased with increasing air temperature, air flow rate and samples thickness and varied in the ranges of 6.5175 × 10-10 to 1.6726 × 10-9 m2 s-1 and 2.7715 × 10-7 to 3.5512 × 10-7 m s-1, respectively. The validation of the Dincer and Dost model indicated a good capability of the model to describe the drying curves of the mushroom slices.

  16. Soil Air Regime of Corn Field Under Plastic Mulching

    Institute of Scientific and Technical Information of China (English)

    CHENYONG-XIANG; LIUXIAO-YI; 等

    1995-01-01

    The effects of plastic mulching on soil aeration at the soil depth of 0-100 cm were studied in a corn field.The results indicated that the CO2 concentration of unmulched soil in the 0-100 cm layer ranged from 0.001 to 0.016 m3/m3,and that of mulched oil 0.002 to 0.018m3/m3,about 32,39% higher than the former on the average.Such a CO2 concentration in the soil air is still sutiable for crop growth.The O2 concentration was inversely correlated with CO2 concentration in the soil air (unmulching r=-0.92,mulching r=-0.79*).O2 concentration raged from 0.11 to 0.17m3/m3 in the mulched soil and 0.13 to 0.18m3/m3 in the unmulched soil.By contrast,N2 concentration in soil air remained relatively steady,with no difference between the two treatments.The relationship between the soil respiratory intensity and the depth of a soil layer appeard to be a power function.At the layer of 0-20cm,the soil respiration intensity in the mulched soil was obviously higher than that in the unmulched.Plastic mulching could also affect soil structure.In comparison with the unmulched soil,the content of >0.25mm aggregate and 0.05-0.001mm microaggregate in the mulched soil was reduced by 82.1% and 35.8%,respectively;the soil total porotity,gaseous phase rate and aeration porosity in the depth of 10-20cm were reduced by 2.85%,19.89%and 26.54% respectively ,but contrary at the depth of 0-10cm.

  17. Degradation of Biochemical Activity in Soil Sterilized by Dry Heat and Gamma Radiation

    Science.gov (United States)

    Shih, K. L.; Souza, K. A.

    1978-01-01

    The effect of soil sterilization by dry heat (0.08% relative humidity), gamma radiation, or both on soil phosphatase, urease, and decarboxylase activity was studied. Soil sterilized by a long exposure to dry heat at relatively low temperatures (eight weeks at 100.5 C) retained higher activities than did soil exposed to a higher temperature (two weeks at 124.5 C), while all activity was destroyed by four days at 148.5 C. Sterilization with 7.5 Mrads destroyed less activity than did heat sterilization. The effect of several individually nonsterizing doses of heat radiation is described.

  18. Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and dry forest

    OpenAIRE

    Markesteijn, L.; Iraipi, J.; F. Bongers; Poorter, L.

    2010-01-01

    We determined seasonal variation in soil matric potentials (¿soil) along a topographical gradient and with soil depth in a Bolivian tropical dry (1160 mm y-1 rain) and moist forest (1580 mm y-1). In each forest we analysed the effect of drought on predawn leaf water potentials (¿pd) and drought response (midday leaf water potential at a standardized ¿pd of -0.98 MPa; ¿md) of saplings of three tree species, varying in shade-tolerance and leaf phenology. ¿soil changed during the dry season and ...

  19. Mathematical Modeling and Effect of Various Hot-Air Drying on Mushroom (Lentinus edodes)

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-hui; XIA Chun-yan; TAN Yu-rong; CHEN Long; MING Jian

    2014-01-01

    An experimental study was performed to determine the characteristics and drying process of mushroom (Lentinus edodes) by 6 different hot-air drying methods namely isothermal drying, uniform raise drying, non-uniform raise drying, uniform intermittent drying, non-uniform intermittent drying and combined drying. The chemical composition (dry matter, ash, crude protein, crude fat, total sugars, dietary ifber, and energy), color parameters (L, a*, b*, c*, and h0) and rehydration capacities were determined. Among all the experiments, non-uniform intermittent drying reached a better comprehensive results due to the higher chemical composition, better color quality associated with high bright (26.381±5.842), high color tone (73.670±2.975), low chroma (13.349±3.456) as well as the highest rehydration (453.76%weigh of dried body). Nine kinds of classical mathematical model were used to obtained moisture data and the Midili-kucuk model can be described by the drying process with the coefifcient (R2 ranged from 0.99790 to 0.99967), chi-square (χ2 ranged from 0.00003 to 0.00019) and root mean square error (RMSE ranged from 0.000486 to 0.0012367).

  20. Soil carbon sequestration in traditional farming in Sudanese dry lands

    OpenAIRE

    Ardo, J; Olsson, L.

    2004-01-01

    Do altered land management practices offer possibilities to sequester carbon in the soil and thereby mitigate increasing atmospheric CO2 as well as improve local soil fertility? This study investigates the impact of fallow periods on soil organic carbon in semiarid subsistence agroecosystems on sandy and poor soils in Kordofan, Sudan. The area is characterized by low-input cultivation of millet and sorghum in combination with livestock grazing. Recently, cultivation intensity has increased an...

  1. Polymer tensiometers to characterize unsaturated zone processes in dry soils

    OpenAIRE

    Ploeg, van der, D.T.E.

    2008-01-01

    More frequent and intense droughts due to global climate change, together with an increasing agricultural water use emphasize the importance of understanding root water uptake by plants under water-stressed conditions. Root water uptake is driven by potential gradients between water in the soil and in the root. In unsaturated soil, the soil water matric potential is often the largest component of the total soil water potential. Tensiometers are commonly used to measure the pressure-equivalent...

  2. Effect of microwave and air drying of parboiled rice on stabilization of rice bran oil

    OpenAIRE

    Rizk, Laila F.; Basyony, A. E.; Doss, Hanaa A.

    1995-01-01

    Two rice varieties, Giza 175 (short grain) and Giza 181 (long grain) were partDoiled by soaking the grains at room temperature for 20 hours and steaming for 15 min then dried either at room temperature or by microwave. The results indicated that air and microwave drying significantly increased oil extraction in both rice bran varieties. Parboiling followed by air or microwave drying produced a slight change on protein, fiber and ash content of rice bran and reduced the development of free fat...

  3. Patterns of cracking in soils due to drying and wetting cycles

    OpenAIRE

    Ledesma Villalba, Alberto; Cordero Arias, Josbel Andreina; Cuadrado Cabello, Agustín; Prat Catalán, Pere

    2014-01-01

    There is a well reported evidence of cracking in clayey or silty soils when drying. Shrinkage in the soil mass and also boundary conditions generate a nonhomogeneous stress state locally producing tensile stresses and eventually cracking. This process has been analysed in detail by several authors. However, the evolution of such cracks due to further relative humidity changes (i.e. wetting and drying again) has been rarely considered in the reported experiments. This paper describes a particu...

  4. Root water potential integrates discrete soil physical properties to influence ABA signalling during partial rootzone drying.

    Science.gov (United States)

    Dodd, Ian C; Egea, Gregorio; Watts, Chris W; Whalley, W Richard

    2010-08-01

    To investigate the influence of different growing substrates (two mineral, two organic) on root xylem ABA concentration ([ABA](root)) and the contribution of the drying root system to total sap flow during partial rootzone drying (PRD), sunflower (Helianthus annuus L.) shoots were grafted onto the root systems of two plants grown in separate pots. Sap flow through each hypocotyl was measured below the graft union when one pot ('wet') was watered and other ('dry') was not. Each substrate gave unique relationships between dry pot matric potential (Psi(soil)), volumetric water content ((v)) or penetrometer resistance (Q) and either the fraction of photoperiod sap flow from roots in drying soil or [ABA](root). However, decreased relative sap flow, and increased [ABA](root), from roots in drying soil varied with root water potential (Psi(root)) more similarly across a range of substrates. The gradient between Psi(soil) and Psi(root) was greater in substrates with high sand or peat proportions, which may have contributed to a more sensitive response of [ABA](root) to Psi(soil) in these substrates. Whole plant transpiration was most closely correlated with the mean Psi(soil) of both pots, and then with detached leaf xylem ABA concentration. Although Psi(root) best predicted decreased relative sap flow, and increased [ABA](root), from roots in drying soil across a range of substrates, the inaccessibility of this variable in field studies requires a better understanding of how measurable soil variables (Psi(soil), (v), Q) affect Psi(root). PMID:20591896

  5. The effect of air temperature on the sappan wood extract drying

    Science.gov (United States)

    Djaeni, M.; Triyastuti, M. S.; Asiah, N.; Annisa, A. N.; Novita, D. A.

    2015-12-01

    The sappan wood extract contain natural colour called brazilin that can be used as a food colouring and antioxidant. The product is commonly found as a dry extract powder for consummer convenience. The spray dryer with air dehumidification can be an option to retain the colour and antioxidant agent. This paper discusses the effect of air temperature on sappan wood extract drying that was mixed with maltodextrin. As responses, the particle size, final moisture content, and extract solubility degradation were observed. In all cases, the process conducted in temperature ranging 90 - 110°C can retain the brazilin quality as seen in solubility and particle size. In addition, the sappan wood extract can be fully dried with moisture content below 2%. Moreover, with the increase of air temperature, the particle size of dry extract can be smaller.

  6. Effect of hot-air drying on the physicochemical properties of kaffir lime leaves (Citrus hystrix)

    OpenAIRE

    Juhari, Nurul Hanisah Binti; Lasekan, Ola; Muhammad, Kharidah; Karim, Shahrim

    2013-01-01

    The effect of hot-air drying namely drying time (3-15 h), drying temperature (40-80°C) and loading capacity (0.5-2.0 kg/m2 ) on the physicochemical characteristics of kaffir lime leaves was optimized using Response Surface Methodology. Twenty treatments were assigned based on the second- order CCD including 6 center points, 6 axial points and 8 factorial points. The quality of dried kaffir lime leaves was evaluated by determining moisture content, water activity, texture (brittleness) and Hun...

  7. Mathematical modelling of thin layer hot air drying of carrot pomace.

    Science.gov (United States)

    Kumar, Navneet; Sarkar, B C; Sharma, H K

    2012-02-01

    Thin layer carrot pomace drying characteristics were evaluated in a laboratory scale hot air forced convective dryer. The drying experiments were carried out at 60, 65, 70 & 75 °C and at an air velocity of 0.7 m/s. Mathematical models were tested to fit drying data of carrot pomace. The whole drying process of carrot pomace took place in a falling rate period except a very short accelerating period at the beginning. The average values of effective diffusivity ranged from 2.74 × 10(-9) to 4.64 × 10(-9) m(2)/s for drying carrot pomace. The activation energy value was 23.05 kJ/mol for the whole falling rate period. PMID:23572823

  8. Persistent Soil Seed Banks for Natural Rehabilitation of Dry Tropical Forests in Northern Ethiopia

    OpenAIRE

    Gebrehiwot, K; HEYN, M; Reubens, B; Hermy, M.; Muys, B.

    2007-01-01

    Dry tropical forests are threatened world-wide by conversion to grazing land, secondary forest, savannah or arable land. In Ethiopia, natural dry forest cover has been decreasing at an alarming rate over the last decennia and has reached a critical level. Efforts like the rehabilitation of dry forests to curb this ecological degradation, need a stronger scientific basis than currently available. The aim of the present research was to test the hypothesis whether soil seed banks can contribute ...

  9. Analysis and Modeling of Wangqing Oil Shale Drying Characteristics in a Novel Fluidized Bed Dryer with Asynchronous Rotating Air Distributor

    Institute of Scientific and Technical Information of China (English)

    Yang Ning; Zhou Yunlong; Miao Yanan

    2016-01-01

    In order to replace the conventional distributor, a novel asynchronous rotating air distributor, which can optimize the drying ability of lfuidized bed and strengthen the drying performance of oil shale particles, is creatively designed in this study. The rotating speed of the asynchronous rotating air distributor with an embedded center disk and an encircling disk is regulated to achieve the different air supply conditions. The impacts of different drying conditions on the drying characteristic of Wangqing oil shale particles are studied with the help of electronic scales. The dynamics of experimental data is analyzed with 9 common drying models. The results indicate that the particles distribution in lfuidized bed can be improved and the drying time can be reduced by decreasing the rotating speed of the embedded center disk and increasing the rotating speed of the encircling disk. The drying process of oil shale particles involves a rising drying rate period, a constant drying rate period and a falling drying rate period. Regulating the air distributor rotating speed reasonably will accelerate the shift of particles from the rising drying rate period to the falling drying rate period directly. The two-term model ifts properly the oil shale particles drying simulation among 9 drying models at different air supply conditions. Yet the air absorbed in the particles’ pores is diffused along with the moisture evaporation, and a small amount of moisture remains on the wall of lfuidized bed in each experiment, thus, the values of drying simulation are less than the experimental values.

  10. Air pollution dry deposition: radioisotopes as particles and volatiles

    International Nuclear Information System (INIS)

    This study focuses on determining volcanic ash and ambient airborne solids concentrations at various sampling sites subsequent to the Mt. St. Helens' eruption in order to develop an experimental basis for models predicting removal of airborne particles and gases by dry deposition onto outdoor surfaces. In addition, deposition rates were determined using dual tracer techniques in the field and in a wind tunnel in the laboratory

  11. Air-soil exchange of mercury from background soils in the United States.

    Science.gov (United States)

    Ericksen, J A; Gustin, M S; Xin, M; Weisberg, P J; Fernandez, G C J

    2006-08-01

    The air-surface exchange of mercury (Hg) was measured, using a dynamic polycarbonate flux chamber, for soils with low or "background" Hg concentrations (pine forest ecosystems (n=1326 soil flux measurements at 46 individual sites). An overall soil Hg flux of 0.9+/-0.2 ng/m2/h for these background soils was obtained by averaging the means for the different locations. Soil Hg fluxes were significantly lower in dark conditions than in the light for all but the grassland sites. Mean inlet air Hg concentrations were 1.0+/-0.1 ng/m3 in the dark and 1.3+/-0.2 ng/m3 in the light. Soil temperature inside and outside of the chamber, air temperature, relative humidity, and irradiance were measured concurrently with soil Hg flux. Soil-air Hg exchange was weakly predicted by environmental variables (R2 from 0.07 to 0.52). For a single location, flux was better correlated with soil moisture than other measured environmental parameters, suggesting that soil moisture might be an important driver for Hg emissions from background soils. In addition, based on data collected we suggest some quality control measures for use of Tekran 2537A analyzers when measuring low mercury fluxes. Using basic scaling procedures, we roughly estimate that natural emissions from soils in the contiguous U.S. release approximately 100 Mg/yr of Hg to the atmosphere. PMID:16181661

  12. Soil concentrations, occurrence, sources and estimation of air-soil exchange of polychlorinated biphenyls in Indian cities.

    Science.gov (United States)

    Chakraborty, Paromita; Zhang, Gan; Li, Jun; Selvaraj, Sakthivel; Breivik, Knut; Jones, Kevin C

    2016-08-15

    Past studies have shown potentially increasing levels of polychlorinated biphenyls (PCBs) in the Indian environment. This is the first attempt to investigate the occurrence of PCBs in surface soil and estimate diffusive air-soil exchange, both on a regional scale as well as at local level within the metropolitan environment of India. From the north, New Delhi and Agra, east, Kolkata, west, Mumbai and Goa and Chennai and Bangalore in the southern India were selected for this study. 33 PCB congeners were quantified in surface soil and possible sources were derived using positive matrix factorization model. Net flux directions of PCBs were estimated in seven major metropolitan cities of India along urban-suburban-rural transects. Mean Σ33PCBs concentration in soil (12ng/g dry weight) was nearly twice the concentration found in global background soil, but in line with findings from Pakistan and urban sites of China. Higher abundance of the heavier congeners (6CB-8CB) was prevalent mostly in the urban centers. Cities like Chennai, Mumbai and Kolkata with evidence of ongoing PCB sources did not show significant correlation with soil organic carbon (SOC). This study provides evidence that soil is acting as sink for heavy weight PCB congeners and source for lighter congeners. Atmospheric transport is presumably a controlling factor for occurrence of PCBs in less polluted sites of India. PMID:27136304

  13. Dry storage systems with free convection air cooling

    International Nuclear Information System (INIS)

    Several design principles to remove heat from the spent fuel by free air convection are illustrated and described. The key safety considerations were felt to be: loss of coolant is impossible as the passive system uses air as a coolant; overheating is precluded because as the temperatures of the containers rises the coolant flow rate increases; mass of the storage building provides a large heat sink and therefore a rapid temperature rise is impossible; and lack of any active external support requirements makes the cooling process less likely to equipment or operator failures. An example of this type of storage already exists. The German HTGR is operated with spherical graphite fuel elements which are stored in canister and in storage cells. The concept is a double cooling system with free convection inside the cells and heat exchange via two side walls of the cell to the ambient air in the cooling ducts. Technical description of the TN 1300 cask is also presented

  14. Modelling pesticide volatilization after soil application using the mechanistic model Volt'Air

    Science.gov (United States)

    Bedos, Carole; Génermont, Sophie; Le Cadre, Edith; Garcia, Lucas; Barriuso, Enrique; Cellier, Pierre

    Volatilization of pesticides participates in atmospheric contamination and affects environmental ecosystems including human welfare. Modelling at relevant time and spatial scales is needed to better understand the complex processes involved in pesticide volatilization. Volt'Air-Pesticides has been developed following a two-step procedure to study pesticide volatilization at the field scale and at a quarter time step. Firstly, Volt'Air-NH 3 was adapted by extending the initial transfer of solutes to pesticides and by adding specific calculations for physico-chemical equilibriums as well as for the degradation of pesticides in soil. Secondly, the model was evaluated in terms of 3 pesticides applied on bare soil (atrazine, alachlor, and trifluralin) which display a wide range of volatilization rates. A sensitivity analysis confirmed the relevance of tuning to K h. Then, using Volt'Air-Pesticides, environmental conditions and emission fluxes of the pesticides were compared to fluxes measured under 2 environmental conditions. The model fairly well described water temporal dynamics, soil surface temperature, and energy budget. Overall, Volt'Air-Pesticides estimates of the order of magnitude of the volatilization flux of all three compounds were in good agreement with the field measurements. The model also satisfactorily simulated the decrease in the volatilization rate of the three pesticides during night-time as well as the decrease in the soil surface residue of trifluralin before and after incorporation. However, the timing of the maximum flux rate during the day was not correctly described, thought to be linked to an increased adsorption under dry soil conditions. Thanks to Volt'Air's capacity to deal with pedo-climatic conditions, several existing parameterizations describing adsorption as a function of soil water content could be tested. However, this point requires further investigation. Practically speaking, Volt'Air-Pesticides can be a useful tool to make

  15. Organochlorine pesticides in soils of Mexico and the potential for soil-air exchange

    International Nuclear Information System (INIS)

    The spatial distribution of organochlorine pesticides (OCs) in soils and their potential for soil-air exchange was examined. The most prominent OCs were the DDTs (Geometric Mean, GM = 1.6 ng g-1), endosulfans (0.16 ng g-1), and toxaphenes (0.64 ng g-1). DDTs in soils of southern Mexico showed fresher signatures with higher FDDTe = p,p'-DDT/(p,p'-DDT + p,p'-DDE) and more racemic o,p'-DDT, while the signatures in the central and northern part of Mexico were more indicative of aged residues. Soil-air fugacity fractions showed that some soils are net recipients of DDTs from the atmosphere, while other soils are net sources. Toxaphene profiles in soils and air showed depletion of Parlar 39 and 42 which suggests that soil is the source to the atmosphere. Endosulfan was undergoing net deposition at most sites as it is a currently used pesticide. Other OCs showed wide variability in fugacity, suggesting a mix of net deposition and volatilization. - Chemical profiles of residues and soil-air fugacities are used to assess the potential of soil as a source of organochlorine pesticides to the air of Mexico.

  16. Air and Soil Water Vapour Density Variations in Akungba Akoko

    OpenAIRE

    Afolabi O.M.

    2015-01-01

    – A temperature and humidity measuring equipment constructed with Silicon lab Si7015 integrated circuit sensor was used to monitor temperature and humidity, compute water saturation and vapour densities for air and soil and to interpret three days variations in Akungba Akoko. The sensors were inserted 5 cm into the soil and 2m away in the troposphere. Two hour records of both parameters were taken from 9 am to 5 pm for 3 days. Air and soil water saturation and vapour density data were compute...

  17. Soil Crust Changes due to Wetting and Drying Analyzed by Non-Invasive Images

    International Nuclear Information System (INIS)

    In this work a γ-ray computed tomography (CT) scanner was used to evaluate soil crust changes due to wetting and drying (W-D) cycles. Changes in soil porous system (SPS) due to W-D cycles of samples with crust have important practical consequences, because they can affect the soil water retention curve (SWRC) representativeness. CT data allowed detailed analyses of the soil bulk density (db) for thick layers, which cannot be achieved by traditional methods commonly used in soil physics. It was also possible to observe a decrease in db in the crust region. These results show that important changes can occur in SPS during SWRC evaluations.

  18. Effect of Drying on Heavy Metal Fraction Distribution in Rice Paddy Soil

    OpenAIRE

    Qi, Yanbing; Huang, Biao; Darilek, Jeremy Landon

    2014-01-01

    An understanding of how redox conditions affect soil heavy metal fractions in rice paddies is important due to its implications for heavy metal mobility and plant uptake. Rice paddy soil samples routinely undergo oxidation prior to heavy metal analysis. Fraction distribution of Cu, Pb, Ni, and Cd from paddy soil with a wide pH range was investigated. Samples were both dried according to standard protocols and also preserved under anaerobic conditions through the sampling and analysis process ...

  19. Crop soil air carbon dioxide concentration and sludge

    Energy Technology Data Exchange (ETDEWEB)

    Guiresse, M.; Gers, C.; Dourel, L.; Kaemmerer, M.; Revel, J.C. [Institut National Polytechnique de Toulouse, Toulouse (France). Ecole Nationale Superieure Agronomique de Toulouse

    1995-12-31

    The introduction of organic compounds into the soil may increase carbon dioxide emission and thus change the composition of the soil air and microfauna. These factors were studied in a field experiment in luvi-redoxisoils in the South West of France. The untreated liquid sludge from the wastewater treatment plant of Toulouse was tested. The first field plot was an unploughed plot, without any fertilizer and any sludge; the second was a control plot sown with Zea mays and a standard mineral fertilizer without any sludge; the third plot was sown with Zea mays and a normal amount of sludge; and the last plot was sown with Zea mays and a large amount of sludge. In these plots soil air dioxide carbon concentration during all the maize cultivation was measured using the Draeger field method twice a week. The results showed that burying degradable organic compounds increases soil air CO{sub 2}. 8 refs., 6 figs.

  20. Do drying and rewetting cycles modulate effects of sulfadiazine spiked manure in soil?

    Science.gov (United States)

    Jechalke, Sven; Radl, Viviane; Schloter, Michael; Heuer, Holger; Smalla, Kornelia

    2016-05-01

    Naturally occurring drying-rewetting events in soil have been shown to affect the dissipation of veterinary antibiotics entering soil by manure fertilization. However, knowledge of effects on the soil microbial community structure and resistome is scarce. Here, consequences of drying-rewetting cycles on effects of sulfadiazine (SDZ) in soil planted withDactylis glomerataL. were investigated in microcosms. Manure containing SDZ or not was applied to the pregrown grass and incubated for 56 days in a climate chamber. Water was either added daily or reduced during two drying events of 7 days, each followed by a recovery phase. Total community DNA was analyzed to reveal the effects on the bacterial community structure and on the abundance ofsul1,sul2,intI1,intI2,qacE+qacEΔ1,traNandkorBgenes relative to 16S rRNA genes. 16S rRNA gene-based DGGE fingerprints indicated that drying-rewetting cycles modulated the effects of SDZ on the bacterial community structure in the soil. Furthermore, the SDZ treatment increased the relative abundance of sulfonamide resistance and integrase genes compared to the control. However, this increase was not different between moisture regimes, indicating that drying-rewetting had only a negligible effect on the selection of the resistome by SDZ in the manured soil. PMID:27053757

  1. SOIL AIR CARBON DIOXIDE CONCENTRATIONS IN A NEW ENGLAND SPRUCE-FIR FORESTS

    Science.gov (United States)

    Research and modeling efforts to evaluate soil-soil solution chemical interactions must take into account solution equilibria with soil air CO2. Measurements of soil air CO2 and soil temperature were made in the major horizons of a forest soil in eastern Maine through the 1985 gr...

  2. Experimental investigation of infiltration in soil with occurrence of preferential flow and air trapping

    Science.gov (United States)

    Snehota, Michal; Jelinkova, Vladimira; Sacha, Jan; Cislerova, Milena

    2015-04-01

    Recently, a number of infiltration experiments have not proved the validity of standard Richards' theory of the flow in soils with wide pore size distribution. Water flow in such soils under near-saturated conditions often exhibits preferential flow and temporal instability of the saturated hydraulic conductivity. An intact sample of coarse sandy loam from Cambisol series containing naturally developed vertically connected macropore was investigated during recurrent ponding infiltration (RPI) experiments conducted during period of 30 hours. RPI experiment consisted of two ponded infiltration runs, each followed by free gravitational draining of the sample. Three-dimensional neutron tomography (NT) image of the dry sample was acquired before the infiltration begun. The dynamics of the wetting front advancement was investigated by a sequence of neutron radiography (NR) images. Analysis of NR showed that water front moved preferentially through the macropore at the approximate speed of 2 mm/sec, which was significantly faster pace than the 0.3 mm/sec wetting advancement in the surrounding soil matrix. After the water started to flow out of the sample, changes in the local water content distribution were evaluated quantitatively by subtracting the NT image of the dry sample from subsequent tomography images. As a next stage, the experiment was repeated on a composed sample packed of ceramic and coarse sand. Series of infiltration runs was conducted in the sample with different initial water contents. The neutron tomography data quantitatively showed that both in natural soil sample containing the macropore and in the composed sample air was gradually transported from the region of fine soil matrix to the macropores or to the coarser material. The accumulation of the air bubbles in the large pores affected the hydraulic conductivity of the sample reducing it up to 50% of the initial value. This supports the hypothesis on strong influence of entrapped air amount and

  3. Field evaluation of slot openers for minimum tillage (part 3- Dried soil cover on the slot -

    Directory of Open Access Journals (Sweden)

    Isara Chaorakam

    2009-03-01

    Full Text Available The direction and feature of slot opener can produce different amount of dried soil cover on the slot. Four different slot openers, namely of a bubble coulter, a V-shaped slot opener, a VRA-slot opener and a VRB-slot opener were tested in the rice field which was covered with chopped arable weed. The direction of these four slot openers was set following the direction of travel. Several field trials of all slot openers were carried out to validate their drill performance on sandy loam soil with four different levels of residual density (0, 2, 4, 6 t/ha and three levels of soil moisture content (31.67, 46.34, 49.07 %. Significant interactions among the major factors were discussed for each slot opener. High amounts of dried soil cover on the slot were discerned in the case of a VRA-slot opener, especially under lower levels of soil moisture content. Some amount of dried soil cover on the slots was observed for the VRB-slot opener. Generally, dried soil cover on the slot tended to decrease with the increase of residual density after the operation of the bubble coulter and the V-shaped slot opener, due partly to hairpinned residue in their slots.

  4. Soil Geochemical Control Over Nematode Populations in Bull Pass, McMurdo Dry Valleys, Antarctica

    Science.gov (United States)

    Poage, M. A.; Barrett, J. E.; Virginia, R. A.; Wall, D. H.

    2005-12-01

    The McMurdo Dry Valleys occupy the largest ice-free region of Antarctica and are characterized by climatic conditions among the most extreme on Earth. Despite the harsh environmental conditions, some soils of the dry valleys host simple low-diversity ecosystems dominated by microbes and several taxa of metazoans, predominantly nematodes. Distributions, abundance, and diversity of these biota appear to be related to the highly variable soil geochemistry (pH, conductivity, nitrate, sulfate, chloride) of the dry valleys. Bull Pass is a glacially carved valley within the dry valleys. An ancient lake margin near the valley floor creates a continuous gradient spanning the full range of geochemical parameters found across the entire McMurdo Dry Valleys system. This unique setting provides the opportunity to systematically investigate the soil geochemical control on local biodiversity and establish, on the spatial scale of hundreds of meters, correlations between nematode populations and individual geochemical parameters that have application at the regional scale. We measured soil geochemistry and nematode population data from a 1500-meter transect across this ancient lake margin. There were significant negative correlations between live nematode abundance and concentrations of soil nitrate, sulfate and chloride as well as total soil salinity, consistent with recent laboratory experiments showing strong salinity inhibition of nematode survival. A logistical regression analysis based on a compilation of published datasets from across the dry valleys was designed to calculate the probably of live nematode populations occurring given a particular soil chemistry, using the dataset from the Bull Pass transect as a case study to field-test the model. Small-scale chemical and biological gradients can provide insights on the distribution of soil biota at much larger regional scales.

  5. Microbial community dynamics induced by rewetting dry soil: summer precipitation matters

    Science.gov (United States)

    Barnard, Romain; Osborne, Catherine; Firestone, Mary

    2015-04-01

    The massive soil CO2 efflux associated with rewetting dry soils after the dry summer period significantly contributes to the annual carbon budget of Mediterranean grasslands. Rapid reactivation of soil heterotrophic activity and available carbon are both required to fuel the CO2 pulse. Better understanding of the effects of altered summer precipitation on the metabolic state of indigenous microorganisms may be important in predicting future changes in carbon cycling. We investigated the effects of a controlled rewetting event on the soil CO2 efflux pulse and on the present (DNA-based) and potentially active (rRNA-based) soil bacterial and fungal communities in intact soil cores previously subjected to three different precipitation patterns over four months (full summer dry season, extended wet season, and absent dry season). Phylogenetic marker genes for bacteria (16S) and fungi (28S) were sequenced before and after rewetting, and the abundance of these genes and transcripts was measured. Even after having experienced markedly different antecedent water conditions, the potentially active bacterial communities showed a consistent wet-up response, reflecting contrasting life-strategies for different groups. Moreover, we found a significant positive relation between the extent of change in the structure of the potentially active bacterial community and the magnitude of the CO2 pulse upon rewetting dry soils. We suggest that the duration of severe dry conditions (predicted to change under future climate) is important in conditioning the response potential of the soil bacterial community to wet-up as well as in framing the magnitude of the associated CO2 pulse.

  6. Gamma ray computed tomography to evaluate wetting/drying soil structure changes

    International Nuclear Information System (INIS)

    Wetting and drying (W-D) cycles can cause strong modifications of the structure of a soil, especially in pore distribution, which reflects the temporal and spatial distribution of soil water and, consequently, these processes can affect soil water and nutrient retention and movement. These alterations have important practical consequences when calculating soil water storages and matric potentials, widely used in irrigation management. The present paper has as objective to use gamma ray computed tomography (GCT) as a tool to investigate possible modifications in soil structure induced by W-D cycles and to analyze how these alterations can affect soil water retention. The GCT scanner used was a first generation system with a fixed source-detector arrangement, with a radioactive gamma ray source of 241Am. Soil samples were taken from profiles of three different soils characterized as Xanthic Ferralsol (Fx), Eutric Nitosol (Ne) and Rhodic Ferralsol (Fr). Eighteen samples (50 cm3), six from each soil, were submitted to none (T0), three (T1) and nine (T2) wetting/drying cycles. Based on image analysis it was possible to detect modifications in soil structure in all samples after wetting/drying cycles for all treatments. Tomographic unit profiles of the samples permitted to identify an increase on soil porosity with the increase in the number of wetting/drying cycles and it was also possible to quantify the average porosity values. The statistical test (Duncan test) indicates that there are significant differences between treatments for all samples at the 5% significance level

  7. Effects of Dry Air Intrusion on MJO Initiation during DYNAMO (Invited)

    Science.gov (United States)

    Chen, S. S.; Kerns, B. W.; Savarin, A.

    2013-12-01

    One of the challenging issues in MJO initiation over the equatorial Indian Ocean is interaction of convection and environmental moisture. It involves complex, multi-scale processes from entrainment/detrainment of cloud, convective downdraft and cold pools affecting the air-sea interface, to large-scale advection controlled by tropical and extratropical circulation. Observations from the DYNAMO field campaign in 2011 show that dry air intrusion into the equatorial Indian Ocean affects convection on both synoptic and MJO time scales. During mid-late November, a strong MJO event, refereed to as MJO2, developed over the DYNAMO array, which has the best coverage of the observational platforms including two aircraft, two research vessels, and island stations. This study focuses on two aspects of the dry air intrusion during MJO2: 1) convective cold pool structure and recovery related to convective-environmental moisture interaction, and 2) dry air intrusion and synoptic variability in convection/precipitation in MJO initiation. Convective downdraft can be affected by environmental water vapor due to entrainment by the convective clouds. Mid-level dry air observed during the convectively suppressed phase of MJO2 seems to enhance convective downdraft by increasing evaporation and, therefore, the strength of the downdraft and cold pools. We examine the convective cold pool structure and boundary layer recovery using the NOAA P-3 aircraft observations, include flight-level, Doppler radar, and GPS dropsonde data. The depth and strength of convective cold pools are defined by the negative buoyancy from the dropsonde data. Recovery of the cold pools in the boundary layer is determined by not only the strength and depth of the cold pools but also the air-sea heat and moisture fluxes. Given that the water vapor and surface winds are distinct for the convectively active and suppressed phases of MJO2, the aircraft data are stratified by the two different large-scale regimes of MJO2

  8. Estimation of whole lemon mass transfer parameters during hot air drying using different modelling methods

    Science.gov (United States)

    Torki-Harchegani, Mehdi; Ghanbarian, Davoud; Sadeghi, Morteza

    2015-08-01

    To design new dryers or improve existing drying equipments, accurate values of mass transfer parameters is of great importance. In this study, an experimental and theoretical investigation of drying whole lemons was carried out. The whole lemons were dried in a convective hot air dryer at different air temperatures (50, 60 and 75 °C) and a constant air velocity (1 m s-1). In theoretical consideration, three moisture transfer models including Dincer and Dost model, Bi- G correlation approach and conventional solution of Fick's second law of diffusion were used to determine moisture transfer parameters and predict dimensionless moisture content curves. The predicted results were then compared with the experimental data and the higher degree of prediction accuracy was achieved by the Dincer and Dost model.

  9. Effects of convective air drying temperature on nutritional quality and colour of watercress (Nasturtium officinale)

    OpenAIRE

    Pichmony, E. K.; Araújo, Ana C.; Oliveira, Sara M.; Ramos, Inês N.; Teresa R.S. Brandão; Silva, Cristina L. M.

    2015-01-01

    Watercress (Nasturtium officinale) is one of the most popular leafy vegetables consumed in the world, either fresh or cooked, presenting high contents of phytochemicals and bioactive compounds. However, due to its high moisture content (91% w.b.), this vegetable is easily perishable. To prolong shelf life and provide the convenient transportation, dried watercress might be a novel product for consumption in soups and other recipes. Convective air drying is an affordable process, b...

  10. Controls of Soil Spatial Variability in a Dry Tropical Forest

    OpenAIRE

    Pulla, Sandeep; Riotte, Jean; Suresh, HS; Dattaraja, HS; Sukumar, Raman

    2016-01-01

    We examined the roles of lithology, topography, vegetation and fire in generating local-scale (= 1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a perman...

  11. Microbial responses to carbon and nitrogen supplementation in an Antarctic dry valley soil

    DEFF Research Database (Denmark)

    Dennis, P. G.; Sparrow, A. D.; Gregorich, E. G.;

    2013-01-01

    organic carbon concentration, indicating efficient conversion of soil organic carbon into microbial biomass and rapid turnover of soil organic carbon. The ELFA concentrations increased significantly in response to carbon additions, indicating that carbon supply was the main constraint to microbial...... activity. The large ELFA concentrations relative to soil organic carbon and the increases in ELFA response to organic carbon addition are both interpreted as evidence for the soil microbial community containing organisms with efficient scavenging mechanisms for carbon. The diversity of the ELFA profiles......The soils of the McMurdo Dry Valleys are exposed to extremely dry and cold conditions. Nevertheless, they contain active biological communities that contribute to the biogeochemical processes. We have used ester-linked fatty acid (ELFA) analysis to investigate the effects of additions of carbon and...

  12. Numerical and Experimental Quantification of coupled water and water vapor fluxes in very dry soils.

    Science.gov (United States)

    Madi, Raneem; de Rooij, Gerrit

    2015-04-01

    In arid and semi-arid regions with deep groundwater and very dry soils, vapor movement in the vadose zone may be a major component in the total water flux. Therefore, the coupled movement of liquid water, water vapor and heat transport in the unsaturated zone should be explicitly considered to quantify subsurface water fluxes in such regions. Only few studies focused on the importance of vapor water diffusion in dry soils and in many water flow studies in soil it was neglected. We are interested in the importance of water vapor diffusion and condensation in very dry sand. A version of Hydrus-1D capable of solving the coupled water vapor and heat transport equations will be used to do the numerical modeling. The soil hydraulic properties will be experimentally determined. A soil column experiment was developed with negligible liquid flow in order to isolate vapor flux for testing. We have used different values of initial water contents trying to generate different scenarios to assess the role of the water vapor transport in arid and semi-arid soils and how it changes the soil water content using different soil hydraulic parametrization functions. In the session a preliminary experimental and modelling results of vapor and water fluxes will be presented.

  13. Effect of osmotic pretreatment on air drying characteristics and colour of pepper (Capsicum spp) cultivars

    OpenAIRE

    Falade, Kolawole Olumuyiwa; Oyedele, Olaniyi O.

    2010-01-01

    Air-drying characteristics of fresh and osmotically pretreated (40°B, 50°B and 60°B sucrose solutions for 9 h) four pepper cultivars namely, Rodo (Capsicum annuum), Shombo (Capsicum frutescens), Bawa (Capsicum frutenscens) and Tatashe (Capsicum annuum), and CIE L*a*b* parameters of air-dried (50, 60, 70 and 80 °C) peppers were investigated. Moisture diffusivity and activation energy (Ea) were calculated from Fick’s law and analogous Arrhenius equation, respectively. Colour difference, chroma ...

  14. Control of aromatic-waste air streams by soil bioreactors

    International Nuclear Information System (INIS)

    Contamination of groundwater resources is a serious environmental problem which is continuing to increase in occurrence in the United States. It has been reported that leaking underground gasoline storage tanks may pose the most serious threat of all sources of groundwater contamination. Gasolines are comprised of a variety of aliphatic and aromatic hydrocarbons. The aromatic portion consists primarily of benzene, toluene, ethylbenzene, and xylenes (BTEX compounds). BTEX compounds are also among the most frequency identified substances at Superfund sites. Pump and treat well systems are the most common and frequently used technique for aquifer restoration. Treatment is often in the form of air stripping to remove the volatile components from the contaminated water. Additionally, soil ventilation processes have been used to remove volatile components from the vadose zone. Both air stripping and soil ventilation produce a waste gas stream containing volatile compounds which is normally treated by carbon adsorption or incineration. Both treatment processes require a substantial capital investment and continual operation and maintenance expenditures. The objective of the study was to examine the potential of using soil bioreactors to treat a waste gas stream produced by air stripping or soil ventilation process. Previous studies have shown that various hydrocarbons can be successfully treated with soils. The study examined the removal of BTEX compounds within soil columns and the influence of soil type, inlet concentration, and inlet flow rate on the removal efficiency

  15. Mathematical Modeling on Combined Mid-infrared and Hot Air Drying of Beef Meat

    Directory of Open Access Journals (Sweden)

    Xiao-Lei Xie

    2015-05-01

    Full Text Available To investigate the drying models and characteristics of Combined Mid-Infrared and Hot Air (CMIHA drying BEEF MEAT (BM, a laboratory scale CMIHA dryer was applied to the treatment of BM samples in a temperature range from 40-70°C, with air velocity of 1m/s and mid-infrared of 2.8-3.1 m. Microsoft visual C sharp (C# was used to develop a Moisture Prediction System (MPS to digitize the prediction process. The results indicated that the Modified Henderson and Pabis model could present better predictions for the moisture transfer than others and the MPS could predict the moisture ratio through the whole drying process conveniently. Besides, higher temperature could accelerate effective diffusivities to increase drying rate, thus shorten the drying time. The activation energy of BM dried with CMIHA was 32.83 kJ/mol. All of these could be used in the design and operation of the combination drying beef meat.

  16. Dry air preservation and corrosion prevention using desiccant dehumidification

    International Nuclear Information System (INIS)

    The preservation and longevity of power station plants is a significant problem, particularly in cold shut down situations for prolonged periods of time, and also in storage of parts prior to installation. Power station protection and equipment preservation using the desiccant method is not new. For many years dehumidification machinery has been employed as a barrier to moisture related degradation. The first rotary desiccant dehumidifiers were installed within the power plant industry in the mid 1960s. Many of these first installations remain in operation today. In order to understand the functioning of a desiccant unit as compared with other air handling systems, it is essential to understand the fundamentals of a psychrometric chart. This article will attempt to give the reader an understanding of the subject. (author)

  17. Modelling gaseous dry deposition in AURAMS: a unified regional air-quality modelling system

    International Nuclear Information System (INIS)

    An upgraded parameterization scheme for gaseous dry-deposition velocities has been developed for a new regional air-quality model with a 91-species gas-phase chemistry mechanism, of which 48 species are ''transported'' species. The well-known resistance analogy to dry deposition is adopted in the present scheme, with both O3 and SO2 taken as base species. Stomatal resistances are calculated for all dry-depositing species using a ''sunlit/shaded big-leaf'' canopy stomatal resistance submodel. Dry-ground, wet-ground, dry-cuticle, and wet-cuticle resistances for O3 and SO2, and parameters for calculating canopy stomatal resistance and aerodynamic resistance for these two base species are given as input parameters for each of the 15 land-use categories and/or five seasonal categories considered by the scheme. Dry-ground, wet-ground, dry-cuticle, and wet-cuticle resistances for the other 29 model species for which dry deposition is considered to be a significant process are scaled to the resistances of O3 and SO2 based on published measurements of their dry deposition and/or their aqueous solubility and oxidizing capacity. Mesophyll resistances are treated as dependent only on chemical species. Field experimental data have then been used to evaluate the scheme's performance for O3 and SO2. Example sets of modelled dry-deposition velocities have also been calculated for all 31 dry-deposited species and 15 land-use categories for different environmental conditions. This new scheme incorporates updated information on dry-deposition measurements and is able to predict deposition velocities for 31 gaseous species for different land-use types, seasons, and meteorological conditions. (author)

  18. Soil water storage, rainfall and runoff relationships in a tropical dry forest catchment

    Science.gov (United States)

    Farrick, Kegan K.; Branfireun, Brian A.

    2014-12-01

    In forested catchments, the exceedance of rainfall and antecedent water storage thresholds is often required for runoff generation, yet to our knowledge these threshold relationships remain undescribed in tropical dry forest catchments. We, therefore, identified the controls of streamflow activation and the timing and magnitude of runoff in a tropical dry forest catchment near the Pacific coast of central Mexico. During a 52 day transition phase from the dry to wet season, soil water movement was dominated by vertical flow which continued until a threshold soil moisture content of 26% was reached at 100 cm below the surface. This satisfied a 162 mm storage deficit and activated streamflow, likely through lateral subsurface flow pathways. High antecedent soil water conditions were maintained during the wet phase but had a weak influence on stormflow. We identified a threshold value of 289 mm of summed rainfall and antecedent soil water needed to generate >4 mm of stormflow per event. Above this threshold, stormflow response and magnitude was almost entirely governed by rainfall event characteristics and not antecedent soil moisture conditions. Our results show that over the course of the wet season in tropical dry forests the dominant controls on runoff generation changed from antecedent soil water and storage to the depth of rainfall.

  19. Modeling Soil Water Retention Curves in the Dry Range Using the Hygroscopic Water Content

    DEFF Research Database (Denmark)

    Chen, Chong; Hu, Kelin; Arthur, Emmanuel;

    2014-01-01

    curves of soils and to predict SWRCs at the dry end using the hygroscopic water content at a relative humidity of 50% (θRH50). The Oswin model yielded satisfactory fits to dry-end SWRCs for soils dominated by both 2:1 and 1:1 clay minerals. Compared with the Oswin model, the Campbell and Shiozawa model......Accurate information on the dry end (matric potential less than −1500 kPa) of soil water retention curves (SWRCs) is crucial for studying water vapor transport and evaporation in soils. The objectives of this study were to assess the potential of the Oswin model for describing the water adsorption...... combined with the Kelvin equation (CS-K) produced better fits to dry-end SWRCs of soils dominated by 2:1 clays but provided poor fits for soils dominated by 1:1 clays. The shape parameter α of the Oswin model was dependent on clay mineral type, and approximate values of 0.29 and 0.57 were obtained for...

  20. Increasing thermal drying temperature of biosolids reduced nitrogen mineralisation and soil N2O emissions.

    Science.gov (United States)

    Case, Sean D C; Gómez-Muñoz, Beatriz; Magid, Jakob; Jensen, Lars Stoumann

    2016-07-01

    Previous studies found that thermally dried biosolids contained more mineralisable organic nitrogen (N) than the raw or anaerobically digested (AD) biosolids they were derived from. However, the effect of thermal drying temperature on biosolid N availability is not well understood. This will be of importance for the value of the biosolids when used to fertilise crops. We sourced AD biosolids from a Danish waste water treatment plant (WWTP) and dried it in the laboratory at 70, 130, 190 or 250 °C to >95 % dry matter content. Also, we sourced biosolids from the WWTP dried using its in-house thermal drying process (input temperature 95 °C, thermal fluid circuit temperature 200 °C, 95 % dry matter content). The drying process reduced the ammonium content of the biosolids and reduced it further at higher drying temperatures. These findings were attributed to ammonia volatilisation. The percentage of mineralisable organic N fraction (min-N) in the biosolids, and nitrous oxide (N2O) and carbon dioxide (CO2) production were analysed 120 days after addition to soil. When incubated at soil field capacity (pF 2), none of the dried biosolids had a greater min-N than the AD biosolids (46.4 %). Min-N was lowest in biosolids dried at higher temperatures (e.g. 19.3 % at 250 °C vs 35.4 % at 70 °C). Considering only the dried biosolids, min-N was greater in WWTP-dried biosolids (50.5 %) than all of the laboratory-dried biosolids with the exception of the 70 °C-dried biosolids. Biosolid carbon mineralisation (CO2 release) and N2O production was also the lowest in treatments of the highest drying temperature, suggesting that this material was more recalcitrant. Overall, thermal drying temperature had a significant influence on N availability from the AD biosolids, but drying did not improve the N availability of these biosolids in any case. PMID:27068895

  1. Effect of microwave and air drying of parboiled rice on stabilization of rice bran oil

    Directory of Open Access Journals (Sweden)

    Rizk, Laila F.

    1995-06-01

    Full Text Available Two rice varieties, Giza 175 (short grain and Giza 181 (long grain were partDoiled by soaking the grains at room temperature for 20 hours and steaming for 15 min then dried either at room temperature or by microwave. The results indicated that air and microwave drying significantly increased oil extraction in both rice bran varieties. Parboiling followed by air or microwave drying produced a slight change on protein, fiber and ash content of rice bran and reduced the development of free fatty acids (F.F.A. In oil bran. Microwave samples have less F.F.A. content than the corresponding samples air dried. Oils from the cold stored rice bran presented lower F.F.A. than the corresponding oil bran stored at room temperature. The ratio between total unsaturated fatty acids and total saturated ones (Tu/Ts decreased after air and microwave drying. Results also show that air drying increased the ratio of total hydrocarbons and total sterols (Tu/Ts in both varieties while microwave decreased it.

    Dos variedades de arroz, Giza 175 (grano corto y Giza 181 (grano largo se precocieron mediante la puesta en remojo de los granos a temperatura ambiente durante 20 horas y cocimiento al vapor durante 15 minutos, luego se secaron a temperatura ambiente o por microondas. Los resultados indicaron que el secado al aire y en microondas aumentó significativamente la extracción del aceite en ambas variedades de salvado de arroz. El precocido seguido del secado al aire o en microondas produjo un cambio pequeño en el contenido en proteína, fibra y ceniza y redujo el desarrollo de ácidos grasos libres (F.F.A. en el aceite de salvado. Las muestras secadas en microondas tuvieron un menor contenido en F.F.A. que las muestras correspondientes al secado en aire. Aceites de salvado de arroz almacenado en frió presentaron menor F.F.A. que los almacenados a temperatura ambiente. La relación entre ácidos grasos insaturados totales y los saturados totales (Tu/Ts disminuy

  2. Organochlorine pesticides in soils and air of southern Mexico: Chemical profiles and potential for soil emissions

    Science.gov (United States)

    Wong, Fiona; Alegria, Henry A.; Jantunen, Liisa M.; Bidleman, Terry F.; Salvador-Figueroa, Miguel; Gold-Bouchot, Gerardo; Ceja-Moreno, Victor; Waliszewski, Stefan M.; Infanzon, Raul

    The extent of organochlorine pesticides (OCs) contamination in southern Mexico was investigated in this study. Biweekly air samplings were carried out in two sites in the state of Chiapas (during 2002-2003), and one in each state of Veracruz and Tabasco (during 2003-2004). Corresponding to the air sampling locations, soil samples were also collected to gauge the soil-air exchange of OCs in the region. ∑DDTs in soils ranged from 0.057 to 360 ng g -1 whereas those in air ranged from 240 to 2400 pg m -3. DDT and metabolite DDE were expressed as fractional values, FDDTe = p, p'-DDT/( p, p'-DDT + p, p'-DDE) and FDDTo = p,p'-DDT/( p,p'-DDT + o,p'-DDT). FDDTe in soils ranged from 0.30 to 0.69 while those in air ranged from 0.45 to 0.84. FDDTe in air at a farm in Chiapas (0.84) was closer to that of technical DDT (0.95) which is suggestive of fresh DDT input. Enantiomer fractions (EF) of o,p'-DDT in air were racemic at all locations (0.500-0.504). However, nonracemic o,p'-DDT was seen in the soils (EFs = 0.456-0.647). Fugacities of OCs in soil ( fs) and air ( fa) were calculated, and the fugacity fraction, ff = fs/( fs + fa) of DDTs ranged from 0.013 to 0.97 which indicated a mix of net deposition ( ff 0.5) from soil among the sites. It is suggested that DDTs in Mexico air are due to a combination of ongoing regional usage and re-emission of old DDT residues from soils. Total toxaphene in soils ranged from 0.066 to 69 ng g -1 while levels in air ranged from 6.2 to 230 pg m -3. Chromatographic profiles of toxaphenes in both air and soil showed depletion of Parlar congeners 39 and 42. Fugacity fractions of toxaphene were within the equilibrium range or above the upper equilibrium threshold boundary. These findings suggested that soil emission of old residues is the main source of toxaphenes to the atmosphere. Results from this study provide baseline data for establishing a long-term OC monitoring program in Mexico.

  3. Hyperventilation with cold versus dry air in 2- to 5-year-old children with asthma

    DEFF Research Database (Denmark)

    Nielsen, Kim G; Bisgaard, Hans

    2005-01-01

    UNLABELLED: Cold air challenge (CACh) has been shown to discriminate between children with asthma and healthy young children. Hyperventilation with dry room-temperature air is a simplified alternative. We compared responsiveness in young children with asthma between two standardized, single-step ...... seemed to induce refractoriness in contrast to DACh, probably because of the additional stimulus from airway cooling. This finding suggests CACh as the preferred method of challenge....

  4. Transport parameters and breakdown voltage characteristics of the dry air and its constituents

    International Nuclear Information System (INIS)

    This paper contains measured breakdown voltage curves and calculated transport parameters for the dry air and gases included in the air composition. The breakdown voltage curves exhibit U-shaped form for the interelectrode separation of 100 μm and departure from the standard Paschen law for a few micrometers gap sizes. The results of calculations provide an insight into similarities and differences between the transport parameters for individual gases and the gas mixture.

  5. Air sparging in low permeability soils

    Energy Technology Data Exchange (ETDEWEB)

    Marley, M.C. [Envirogen, Inc., Canton, MA (United States)

    1996-08-01

    Sparging technology is rapidly growing as a preferred, low cost remediation technique of choice at sites across the United States. The technology is considered to be commercially available and relatively mature. However, the maturity is based on the number of applications of the technology as opposed to the degree of understanding of the mechanisms governing the sparging process. Few well documented case studies exist on the long term operation of the technology. Sparging has generally been applied using modified monitoring well designs in uniform, coarse grained soils. The applicability of sparging for the remediation of DNAPLs in low permeability media has not been significantly explored. Models for projecting the performance of sparging systems in either soils condition are generally simplistic but can be used to provide general insight into the effects of significant changes in soil and fluid properties. The most promising sparging approaches for the remediation of DNAPLs in low permeability media are variations or enhancements to the core technology. Recirculatory sparging systems, sparging/biosparging trenches or curtains and heating or induced fracturing techniques appear to be the most promising technology variants for this type of soil. 21 refs., 9 figs.

  6. SLOPE LITHOLOGIC PROPERTY, SOIL MOISTURE CONDITION AND REVEGETATION IN DRY-HOT VALLEY OF JINSHA RIVER

    Institute of Scientific and Technical Information of China (English)

    XIONG Dong-hong; ZHOU Hong-yi; YANG Zhong; ZHANG Xin-bao

    2005-01-01

    The dry-hot valley of the Jinsha River is one of the typical eco-fragile areas in Southwest China, as well as a focus ofrevegetation study in the upper and middle reaches of the Changjiang River. Due to its extremely dry and hot climate, severely degraded vegetation and the intense soil and water loss, there are extreme difficulties in vegetation restoration in this area and no great breakthrough has ever been achieved on studies of revegetation over the last several decades. Through over ten years' research conducted in the typical areas-the Yuanmou dry-hot valley, the authors found that the lithologic property is one of the crucial factors determining soil moisture conditions and vegetation types in the dry-hot valley, and the rainfall infiltration capability is also one of the key factors affecting the tree growth. Then the revegetation zoning based on different slopes was conducted and revegetation patterns for different zones were proposed.

  7. Weed emergence as influenced by soil moisture and air temperature

    OpenAIRE

    Calado, José; G. Basch; Carvalho, Mário

    2009-01-01

    Abstract Emergence of weed seedlings depends on soil environmental conditions; mainly temperature and moisture, with the latter being fundamental and particularly important in environments which are characterised by irregular amounts and distribution of rainfall throughout the year. Thus, this study looks at the influence of soil moisture and air temperature on the emergence of weed seedlings. The experiment was carried out under controlled environmental conditions, using rings filled with s...

  8. The Resilience of Microbial Community under Drying and Rewetting Cycles of Three Forest Soils

    Science.gov (United States)

    Zhou, Xue; Fornara, Dario; Ikenaga, Makoto; Akagi, Isao; Zhang, Ruifu; Jia, Zhongjun

    2016-01-01

    Forest soil ecosystems are associated with large pools and fluxes of carbon (C) and nitrogen (N), which could be strongly affected by variation in rainfall events under current climate change. Understanding how dry and wet cycle events might influence the metabolic state of indigenous soil microbes is crucial for predicting forest soil responses to environmental change. We used 454 pyrosequencing and quantitative PCR to address how present (DNA-based) and potentially active (RNA-based) soil bacterial communities might response to the changes in water availability across three different forest types located in two continents (Africa and Asia) under controlled drying and rewetting cycles. Sequencing of rRNA gene and transcript indicated that Proteobacteria, Actinobacteria, and Acidobacteria were the most responsive phyla to changes in water availability. We defined the ratio of rRNA transcript to rRNA gene abundance as a key indicator of potential microbial activity and we found that this ratio was increased following soil dry-down process whereas it decreased after soil rewetting. Following rewetting Crenarchaeota-like 16S rRNA gene transcript increased in some forest soils and this was linked to increases in soil nitrate levels suggesting greater nitrification rates under higher soil water availability. Changes in the relative abundance of (1) different microbial phyla and classes, and (2) 16S and amoA genes were found to be site- and taxa-specific and might have been driven by different life-strategies. Overall, we found that, after rewetting, the structure of the present and potentially active bacterial community structure as well as the abundance of bacterial (16S), archaeal (16S) and ammonia oxidizers (amoA), all returned to pre-dry-down levels. This suggests that microbial taxa have the ability to recover from desiccation, a critical response, which will contribute to maintaining microbial biodiversity in harsh ecosystems under environmental perturbations

  9. The Resilience of Microbial Community under Drying and Rewetting Cycles of Three Forest Soils.

    Science.gov (United States)

    Zhou, Xue; Fornara, Dario; Ikenaga, Makoto; Akagi, Isao; Zhang, Ruifu; Jia, Zhongjun

    2016-01-01

    Forest soil ecosystems are associated with large pools and fluxes of carbon (C) and nitrogen (N), which could be strongly affected by variation in rainfall events under current climate change. Understanding how dry and wet cycle events might influence the metabolic state of indigenous soil microbes is crucial for predicting forest soil responses to environmental change. We used 454 pyrosequencing and quantitative PCR to address how present (DNA-based) and potentially active (RNA-based) soil bacterial communities might response to the changes in water availability across three different forest types located in two continents (Africa and Asia) under controlled drying and rewetting cycles. Sequencing of rRNA gene and transcript indicated that Proteobacteria, Actinobacteria, and Acidobacteria were the most responsive phyla to changes in water availability. We defined the ratio of rRNA transcript to rRNA gene abundance as a key indicator of potential microbial activity and we found that this ratio was increased following soil dry-down process whereas it decreased after soil rewetting. Following rewetting Crenarchaeota-like 16S rRNA gene transcript increased in some forest soils and this was linked to increases in soil nitrate levels suggesting greater nitrification rates under higher soil water availability. Changes in the relative abundance of (1) different microbial phyla and classes, and (2) 16S and amoA genes were found to be site- and taxa-specific and might have been driven by different life-strategies. Overall, we found that, after rewetting, the structure of the present and potentially active bacterial community structure as well as the abundance of bacterial (16S), archaeal (16S) and ammonia oxidizers (amoA), all returned to pre-dry-down levels. This suggests that microbial taxa have the ability to recover from desiccation, a critical response, which will contribute to maintaining microbial biodiversity in harsh ecosystems under environmental perturbations

  10. Drying and wetting of Mediterranean soils stimulates decomposition and carbon dioxide emission: the "Birch effect".

    Science.gov (United States)

    Jarvis, Paul; Rey, Ana; Petsikos, Charalampos; Wingate, Lisa; Rayment, Mark; Pereira, João; Banza, João; David, Jorge; Miglietta, Franco; Borghetti, Marco; Manca, Giovanni; Valentini, Riccardo

    2007-07-01

    Observations on the net carbon exchange of forests in the European Mediterranean region, measured recently by the eddy covariance method, have revived interest in a phenomenon first characterized on agricultural and forest soils in East Africa in the 1950s and 1960s by H. F. Birch and now often referred to as the "Birch effect." When soils become dry during summer because of lack of rain, as is common in regions with Mediterranean climate, or are dried in the laboratory in controlled conditions, and are then rewetted by precipitation or irrigation, there is a burst of decomposition, mineralization and release of inorganic nitrogen and CO(2). In forests in Mediterranean climates in southern Europe, this effect has been observed with eddy covariance techniques and soil respiration chambers at the stand and small plot scales, respectively. Following the early work of Birch, laboratory incubations of soils at controlled temperatures and water contents have been used to characterize CO(2) release following the rewetting of dry soils. A simple empirical model based on laboratory incubations demonstrates that the amount of carbon mineralized over one year can be predicted from soil temperature and precipitation regime, provided that carbon lost as CO(2) is taken into account. We show that the amount of carbon returned to the atmosphere following soil rewetting can reduce significantly the annual net carbon gain by Mediterranean forests. PMID:17403645

  11. SOLAR DRYING KINETICS OF DATE PALM FRUITS ASSUMING A STEP-WISE AIR TEMPERATURE CHANGE

    Directory of Open Access Journals (Sweden)

    ABDELGHANI BOUBEKRI

    2009-09-01

    Full Text Available The effect of drying using a step-wise temperature change was studied considering the case of indirect solar drying of the date palm fruit (Phoenix dactylifera L.. The followed procedure consists of building drying kinetics by stages of temperatures resulting from drying, in constant conditions, of the same variety of dates from Algerian and Tunisian origin. A law of daily temperature variation prevailed by 60°C, was deduced from a statement of temperature collected on a laboratory solar dryer prototype. Two drying curve equation models were used and some comparisons were discussed. The results obtained for dates from the two origins highlighted different response times by changing the air temperature and showed the possibility of reaching a fruit with standard moisture content in only one day of drying on the basis of initial water contents ranging from 0.40 to 0.65. This moisture range is in practice allotted to rehydrated dates by water immersion in order to enhance their quality. Experiments conducted in a laboratory solar drier under temperatures oscillating around 50°C and 60°C led to the same end up regarding the drying time ensuring a visually appreciable fruit quality. Results obtained by a simple sensorial test revealed a better quality of date fruits treated by solar drying comparing to those issued from industrial heat treatment units.

  12. Controls of Soil Spatial Variability in a Dry Tropical Forest

    Science.gov (United States)

    Pulla, Sandeep; Riotte, Jean; Suresh, H. S.; Dattaraja, H. S.; Sukumar, Raman

    2016-01-01

    We examined the roles of lithology, topography, vegetation and fire in generating local-scale (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3−-N nor NH4+-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief. PMID:27100088

  13. Polymer tensiometers to characterize unsaturated zone processes in dry soils

    NARCIS (Netherlands)

    Ploeg, van der M.J.

    2008-01-01

    More frequent and intense droughts due to global climate change, together with an increasing agricultural water use emphasize the importance of understanding root water uptake by plants under water-stressed conditions. Root water uptake is driven by potential gradients between water in the soil and

  14. Controls of Soil Spatial Variability in a Dry Tropical Forest.

    Science.gov (United States)

    Pulla, Sandeep; Riotte, Jean; Suresh, H S; Dattaraja, H S; Sukumar, Raman

    2016-01-01

    We examined the roles of lithology, topography, vegetation and fire in generating local-scale (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO3(-)-N nor NH4(+)-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief. PMID:27100088

  15. Thin layer convective air drying of wild edible plant (Allium roseum) leaves: experimental kinetics, modeling and quality.

    Science.gov (United States)

    Ben Haj Said, Leila; Najjaa, Hanen; Farhat, Abdelhamid; Neffati, Mohamed; Bellagha, Sihem

    2015-06-01

    The present study deals with the valorization of an edible spontaneous plant of the Tunisian arid areas: Allium roseum. This plant is traditionally used for therapeutic and culinary uses. Thin-layer drying behavior of Allium roseum leaves was investigated at 40, 50 and 60 °C drying air temperatures and 1 and l.5 m/s air velocity, in a convective dryer. The increase in air temperature significantly affected the moisture loss and reduced the drying time while air velocity was an insignificant factor during drying of Allium roseum leaves. Five models selected from the literature were found to satisfactorily describe drying kinetics of Allium roseum leaves for all tested drying conditions. Drying data were analyzed to obtain moisture diffusivity values. During the falling rate-drying period, moisture transfer from Allium roseum leaves was described by applying the Fick's diffusion model. Moisture diffusivity varied from 2.55 × 10(-12) to 8.83 × 10(-12) m(2)/s and increased with air temperature. Activation energy during convective drying was calculated using an exponential expression based on Arrhenius equation and ranged between 46.80 and 52.68 kJ/mol. All sulfur compounds detected in the fresh leaves were detected in the dried leaves. Convective air drying preserved the sulfur compounds potential formation. PMID:26028758

  16. Air sparging and soil vapor extraction to remediate ground water

    International Nuclear Information System (INIS)

    An Air Sparging and Soil Vapor Extraction System was chosen to remediate petroleum impacted ground water over traditional remedial alternatives, such as ''pump and treat'', to expedite site closure. Field pilot testing, computer modeling and cost benefit analyses performed for several alternatives. Air Sparging and Soil Vapor Extraction pilot studies proved this technology to be the most effective with respect to remedial and economic concerns. Underground Storage Tanks (USTs) were closed at the facility located in North Eastern North Carolina in August of 1992. During UST closure, petroleum impacted ground water and soils were encountered. ATEC performed a Comprehensive Site assessment to delineate the impacted soil and ground water plume. Following completion of the site assessment, a Corrective Action Plan was prepared. As part of the Corrective Action Plan preparation, field pilot testing was performed to evaluate remedial alternatives and provide information for full scale design. The full scale treatment system was installed and started in January 1994. This effective Remedial System was selected over other options due to successful pilot testing results with site closure petitioning scheduled within 12 to 14 months after start up. The Air Sparging System, properly applied, is an effective and ''quick'' remedial option with no generation of ground water for disposal and permitting. This paper concentrates on the Air Sparging application applied at this North Carolina site. Although Vapor extraction was also implemented, this presentation does not elaborate on vapor extraction design or implementation and only discusses vapor extraction where it is directly related to the Air Sparging System

  17. Rapid monitoring of soil, water, and air dusts by direct large-area alpha spectrometry.

    Science.gov (United States)

    Sill, C W

    1995-07-01

    During retrieval and disposition of wastes containing transuranium elements, continuous monitoring of the air, water, and soil for alpha emitters was required to ensure that safety limits were not exceeded and that the waste itself was not disturbed unknowingly. Direct measurements by alpha spectrometry were particularly promising because of their potential speed, sensitivity, and their ability to identify transuranium radionuclides under field conditions. Soil samples or settled dusts were finely ground, suspended in 80% ethanol, sprayed onto circular stainless steel pans, and dried on a hotplate. Water samples were mounted directly by spraying. Air dusts were collected with a high-volume air sampler on 20- by 25-cm membrane filters. The samples were then analyzed directly in a large pressurized gridded ionization chamber without further sample preparation. The lower limits of detection for 10-min counting times were 1.5 Bq g-1 (40 pCi g-1) for 100-mg soil samples, and 4 x 10(-2) Bq m-3 (10(-12) microCi mL-1) for a 10-min air sample taken at 0.4 m3 min-1 (14 cubic feet per minute) and counted without waiting for decay of radon progeny. PMID:7790211

  18. Parametric study of a solar air heater with and without thermal storage for solar drying applications

    Energy Technology Data Exchange (ETDEWEB)

    Aboul-Enein, S.; El-Sebaii, A.A.; Ramadan, M.R.I.; El-Gohary, H.G. [Tanta Univ., Physics Dept., Tanta (Egypt)

    2000-12-01

    A transient analytical model is presented for a flat-plate solar air heater with and without thermal storage. The flowing air temperature is assumed to vary with time and space coordinates. Analytical expressions are obtained for various temperatures of the air heater elements as well as for the temperature of the storage material. The performance of the air heater is investigated by computer simulation using the climatic conditions of Tanta (Lat. 30deg 47' N, Egypt). Effects of design parameters of the air heater such as length (L), width (b), gap spacing between the absorber plate and glass cover (d{sub f}), mass flow rate (m) and thickness and type of the storage material (sand, granite and water) on the outlet and average temperatures of the flowing air are studied. It is found that as L and b increase the average temperatures of flowing air (T{sub fav}) increases up to typical values for these parameters. Typical values for L and b are obtained as 3 and 2 m, respectively. The outlet temperature (T{sub fo}) of flowing air is found to decrease with increasing gap spacing and mass flow rate of air. Improvements in the heater performance with storage have been achieved at the optimum thickness (0.12 m) of the storage material. Therefore, the air heater can be used as a heat source for drying agricultural products and the drying process will continue during night, instead of re-absorption of moisture from the surrounding air. Comparisons between experimental and theoretical results indicated that the proposed mathematical model can be used for estimating the thermal performance of flat-plate solar air heaters with reasonable accuracy. (Author)

  19. Combustion Gas Properties I-ASTM Jet a Fuel and Dry Air

    Science.gov (United States)

    Jones, R. E.; Trout, A. M.; Wear, J. D.; Mcbride, B. J.

    1984-01-01

    A series of computations was made to produce the equilibrium temperature and gas composition for ASTM jet A fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0.

  20. Combustion gas properties. Part 3: Hydrogen gas fuel and dry air

    Science.gov (United States)

    Wear, J. D.; Jones, R. E.; Mcbride, B. J.; Beyerle, R. A.

    1985-01-01

    A series of computations has been made to produce the equilibrium temperature and gas composition for hydrogen gas fuel and dry air. The computed tables and figures provide combustion gas property data for pressures from 0.5 to 50 atmospheres and equivalence ratios from 0 to 2.0. Only sample tables and figures are provided in this report.

  1. Humidifying system design of PEMFC test platform based on the mixture of dry and wet air

    Directory of Open Access Journals (Sweden)

    Tiancai Ma

    2015-01-01

    Full Text Available Based on the present humidifying system of PEMFC test platform, a novel design based on dry and wet air mixture is proposed. Key parameters are calculated, and test platform is built. Three experiments are implemented to test the performance of proposed design. Results show that the new design can meet the requirements, and realize the quick response and accurate control.

  2. Effect of heterogenous and homogenous air gaps on dry heat loss through the garment.

    Science.gov (United States)

    Mert, Emel; Psikuta, Agnes; Bueno, Marie-Ange; Rossi, René M

    2015-11-01

    In real life conditions, the trapped air between the human body and the garment has uneven shape and vary over the body parts as a consequence of the complex geometry of the human body. However, the existing clothing models assume uniform air layer between the human body and the garment or its full contact, which may cause large error in the output of simulations. Therefore, the aim of this study was to investigate the effect of a heterogeneous vertical air gap with different configuration of folds (size and frequency) on dry heat loss using a heated cylinder (Torso). It was found that the presence of folds in the garment led to an increased heat loss from the body in comparison to a homogeneous air gap of comparable size. Interestingly, the size of folds did not have an influence on the dry heat loss. Additionally, the effect of the contact area on dry heat loss became important when exceeding a threshold of about 42%. The results from this study are useful for modelling of a realistic dry heat loss through the clothing and contribute to the improvement of design of protective and active sport garments. PMID:25796204

  3. Coffee husk associated with firewood as fuel for indirect heating of drying air

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes, Edney Alves; Silva, Juarez de Sousa e; Silva, Jadir Nogueira da; Oliveira Filho, Delly [Universidade Federal de Vicosa (DEA/UFV), MG (Brazil). Dept. de Engenharia Agricola; Donzeles, Sergio Mauricio Lopes [Empresa de Pesquisa Agropecuaria de Minas Gerais (EPAMIG), Vicosa, MG (Brazil)

    2008-07-01

    The objective of this work was the performance analysis of a furnace, burning coffee husk associated with firewood to heat the drying air passing through a heat exchanger. For the analysis the temperature variation, the combustion quality, the heat losses and the furnace thermal efficiency were all monitored. Results showed that the furnace average efficiency was 58.3% and the heat losses in the exhaust were 24.3%. The presence of carbon monoxide in the exhaust gases (average 2982.8 ppm) had proven incomplete combustion, and suggesting that the combustion gases can not be used to directly drying of foods. Despite of indirect heating, the presented thermal efficiency indicates that the burning of coffee husks is one economic alternative for air heating in grain drying or in other agricultural processes. (author)

  4. Economical analysis of the spray drying process by pre-dehumidification of the inlet air

    Energy Technology Data Exchange (ETDEWEB)

    Madeira, A.N.; Camargo, J.R. [University of Taubate (UNITAU), SP (Brazil). Mechanical Engineering Dept.

    2009-07-01

    Spray drying is a dehumidification process by atomization in a closed chamber that aims to remove moisture of a product by heat and mass transfer from the product's contained water to the air that, in this process is previously heated. This paper presents a case study for an industry that produces food ingredients. The current process applied in the product to heat the air can uses one of these two systems: a direct heating process that burns liquid petroleum gas in contact with the inlet air or indirect heating that uses a heat exchanger which heat the air. This heating system consumes 90% of the total process energy. However, this inlet air can reach the dehumidifier with high moisture from the atmosphere condition requesting, in this case, more energy consumption according to the year's seasons. This paper promotes a utilization study of the current process through the installation of a pre-dehumidification device of the inlet air and shows a study to three different dehumidification systems that means by refrigeration, adsorption and actual comparing their performance in an energetic and economical point of view. The goals of this study are to analyze the capacity of moisture removing of each removing device, the influence of moisture variation of the inlet air in the process as well as the economic impact of each device in the global system. It concludes that the utilization of dehumidification devices can eliminate the heating system reducing this way the energy consumption. Moreover it promotes the increasing of moisture gradient between the inlet air and the product optimizing the drying process and increasing the global energy efficiency in the global system. Choosing the most appropriate system for the pre-dehumidification device depends on the desired initial and final moisture content of the product, but applying pre-dehumidifiers at the inlet air promotes an energetic optimization in the spray drying process. (author)

  5. Combined effects of precipitation and air temperature on soil moisture in different land covers in a humid basin

    Science.gov (United States)

    Feng, Huihui; Liu, Yuanbo

    2015-12-01

    Soil moisture is a key variable in hydrological processes. Although the combined effects of multiple climatic factors in different land cover conditions are highly valuable for water resource management, a complete understanding of these effects remains unclear. This study used a cluster analysis approach to investigate the combined effects of precipitation and air temperature, rather than a single factor, in different land covers for an area over the Poyang Lake Basin in China from 2003 to 2009. Specifically, monthly soil moisture was classified into eight clusters according to the change in precipitation and air temperature; the clusters describe a range of climates from the extreme of wet-hot to that of dry-cold. For an individual climate factor, our results showed that the contribution of air temperature to soil moisture is greater than that of precipitation, and the effect of air temperature is more sensitive in different land covers. When considering the combined effects of precipitation and air temperature, soil moisture varies with land cover; however, the variation in a normal climate cluster is greater than in an extreme climate cluster. This indicated that land cover is the dominant factor in soil moisture variation in normal climatic conditions, whereas climate is the dominant factor in extreme conditions. As climate shifts from the wet-hot to the dry-cold cluster, soil moisture decreases for all land covers, with the minimum rate occurring in forest conditions. Meanwhile, soil moisture deficit and saturation are more likely to occur in grassland and forest areas, indicating that forest cover might mitigate drought. The results of this study provide an effective approach to investigate the combined effects of climate factors on soil moisture for various land covers in humid areas. This study also supports the management of water resources in changing climates.

  6. Cold Vacuum Drying facility heating, ventilation, and Air Conditioning system design description

    International Nuclear Information System (INIS)

    This System Design Description (SDD) addresses the HVAC system for the CVDF. The CVDF HVAC system consists of five subsystems: (1) Administration building HVAC system; (2) Process bay recirculation HVAC system; (3) Process bay local exhaust HVAC and process vent system; (4) Process general supply/exhaust HVAC system; and (5) Reference air system. The HVAC and reference air systems interface with the following systems: the fire protection control system, Monitoring and Control System (MCS), electrical power distribution system (including standby power), compressed air system, Chilled Water (CHW) system, drainage system, and other Cold Vacuum Drying (CVD) control systems not addressed in this SDD

  7. Pathogen reduction effects of solar drying and soil application in sewage sludge

    OpenAIRE

    ÖĞLENİ, Nurtaç; ÖZDEMİR, Saim

    2010-01-01

    The responses of sludge faecal coliforms, Salmonella, and Ascaris lumbricoides to heat drying, solar dehydration, and inactivation in soil are examined in this study. The presence of Salmonella in raw sludge cake after treatment was low, and absent for most of the cases. Likewise, the viable Ascaris eggs were not determined because of absent or low prevalence. Faecal coliforms, on the other hand, drastically decreased from 4.2 × 107 MPN g-1 Dry Solid (DS) to absence by heat drying. Faecal col...

  8. Changes in the properties of solonetzic soil complexes in the dry steppe zone under anthropogenic impacts

    Science.gov (United States)

    Lyubimova, I. N.; Novikova, A. F.

    2016-05-01

    Long-term studies of changes in the properties of solonetzic soil complexes of the dry steppe zone under anthropogenic impacts (deep plowing, surface leveling, irrigation, and post-irrigation use) have been performed on the Privolzhskaya sand ridge and the Khvalyn and Ergeni plains. The natural morphology of solonetzic soils was strongly disturbed during their deep ameliorative plowing. At present, the soil cover consists of solonetzic agrozems (Sodic Protosalic Cambisols (Loamic, Aric, Protocalcic)), textural (clay-illuvial) calcareous agrozems (Eutric Cambisols (Loamic, Aric, Protocalcic)), agrosolonetzes (Endocalcaric Luvisols (Loamic, Aric, Cutanic, Protosodic), agrochestnut soils (Eutric Cambisols (Siltic, Aric)), and meadowchestnut soils (Haplic Kastanozems). No features attesting to the restoration of the initial profile of solonetzes have been found. The dynamics of soluble salts and exchangeable sodium differ in the agrosolonetzes and solonetzic agrozems. A rise in pH values takes place in the middle part of the soil profiles on the Khvalyn and Ergeni plains.

  9. Effect of additives and steaming on quality of air dried noodles.

    Science.gov (United States)

    Gatade, Abhijeet Arun; Sahoo, Akshaya Kumar

    2015-12-01

    Texture is the most important property for consumer acceptance in cooked noodles. The air dried noodles are known to have higher cooking loss and cooking time, to that of instant fried noodles. But the fat content of instant fried noodles is more. In the present work attempts were made to optimize the moisture content so as to obtain a smooth dough for extruded noodle preparation and develop air dried noodles of low fat content with lesser cooking loss and cooking time. To meet the objectives, the effect of various additives and steaming treatment on cooking quality, sensory attributes, textural properties and microstructure of noodles were studied. Dough prepared by addition of 40 ml water to 100 g flour resulted into formation of a soft dough, leading to production of noodles of improved surface smoothness and maximum yield. The use of additives (5 g oil, 0.2 g guar gum, 2 g gluten and 1 ml of 1 % kansui solution for 100 g of flour) and steaming treatment showed significant effect on noodles quality, with respect to cooking characteristics, sensory attributes and textural properties. The microstructure images justified the positive correlation between the effects of ingredients with steaming and quality parameters of noodles. Air dried noodles with reduced cooking loss (~50 % reduction) with marginal reduction in cooking time was developed, which were having similar characteristics to that of instant fried noodles. Compared to the instant fried noodle, the prepared air dried noodle was having substantially reduced fat content (~70 % reduction). Thus the present study will be useful for guiding extrusion processes for production of air dried noodles having less cooking time and low fat content. PMID:26604421

  10. Preliminary Design of KAIST Micro Modular Reactor with Dry Air Cooling

    Energy Technology Data Exchange (ETDEWEB)

    Baik, Seung Joon; Bae, Seong Jun; Kim, Seong Gu; Lee, Jeong Ik [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2014-05-15

    KAIST research team recently proposed a Micro Modular Reactor (MMR) concept which integrates power conversion unit (PCU) with the reactor core in a single module. Using supercritical CO{sub 2} as a working fluid of cycle can achieve physically compact size due to small turbomachinery and heat exchangers. The objective of this project is to develop a concept that can operate at isolated area. The design focuses especially on the operation in the inland area where cooling water is insufficient. Thus, in this paper the potential for dry air cooling of the proposed reactor will be examined by sizing the cooling system with preliminary approach. The KAIST MMR is a recently proposed concept of futuristic SMR. The MMR size is being determined to be transportable with land transportation. Special attention is given to the MMR design on the dry cooling, which the cooling system does not depend on water. With appropriately designed air cooling heat exchanger, the MMR can operate autonomously. Two types of air cooling methods are suggested. One is using fan and the other is utilizing cooling tower for the air flow. With fan type air cooling method it consumes about 0.6% of generated electricity from the nuclear reactor. Cooling tower occupies an area of 227 m{sup 2} and 59.6 m in height. This design is just a preliminary estimation of the dry cooling method, and therefore more detailed and optimal design will be followed in the next phase.

  11. Preliminary Design of KAIST Micro Modular Reactor with Dry Air Cooling

    International Nuclear Information System (INIS)

    KAIST research team recently proposed a Micro Modular Reactor (MMR) concept which integrates power conversion unit (PCU) with the reactor core in a single module. Using supercritical CO2 as a working fluid of cycle can achieve physically compact size due to small turbomachinery and heat exchangers. The objective of this project is to develop a concept that can operate at isolated area. The design focuses especially on the operation in the inland area where cooling water is insufficient. Thus, in this paper the potential for dry air cooling of the proposed reactor will be examined by sizing the cooling system with preliminary approach. The KAIST MMR is a recently proposed concept of futuristic SMR. The MMR size is being determined to be transportable with land transportation. Special attention is given to the MMR design on the dry cooling, which the cooling system does not depend on water. With appropriately designed air cooling heat exchanger, the MMR can operate autonomously. Two types of air cooling methods are suggested. One is using fan and the other is utilizing cooling tower for the air flow. With fan type air cooling method it consumes about 0.6% of generated electricity from the nuclear reactor. Cooling tower occupies an area of 227 m2 and 59.6 m in height. This design is just a preliminary estimation of the dry cooling method, and therefore more detailed and optimal design will be followed in the next phase

  12. Air permeability of powder: a potential tool for Dry Powder Inhaler formulation development.

    Science.gov (United States)

    Le, V N P; Robins, E; Flament, M P

    2010-11-01

    Dry Powder Inhalers have drawn great attention from pharmaceutical scientists in recent years in particular those consisting of low-dose micronized drug particles associated with larger carrier particles and called interactive mixtures. However, there is little understanding of the relation between bulk powder properties such as powder structure and its aerodynamic dispersion performance. The aim of this work was to develop a simple method to measure the air permeability of interactive mixtures used in Dry Powder Inhalers by using Blaine's apparatus--a compendial permeameter and to relate it to the aerodynamic behaviour. The study was done with fluticasone propionate and terbutaline sulphate as drug models that were blended with several lactoses having different particle size distribution thus containing different percentages of fine particle lactose. The quality of the blends was examined by analysing the drug content uniformity. Aerodynamic evaluation of fine particle fraction was obtained using a Twin Stage Impinger. A linear correlation between a bulk property--air permeability of packed powder bed--and the fine particle fraction of drug was observed for the tested drugs. The air permeability reflects the quantity of the free particle fraction in the interparticulate spaces of powder bed that leads to fine particle fraction during fluidization in air flow. A theoretical approach was developed in order to link the air permeability of powder bed and drag force acting on powders during aerosolization process. The permeability technique developed in this study provides a potential tool for screening Dry Powder Inhaler formulations at the development stage. PMID:20854906

  13. Sulfate Attack Resistance of Air-entrained Silica Fume Concrete under Dry-Wet Cycle Condition

    Institute of Scientific and Technical Information of China (English)

    YANG Jiansen; WANG Peiming; LI Haoxin; YANG Xu

    2016-01-01

    Based on the erosion resistant coefficient, the effects of water-cement ratio, air-entrained, silica fume content and sand ratio on the sulfate attack resistance of air-entrained silica fume concrete were studied by orthogonal experiments in order to explore its sulfate attack resistance under dry-wet condition. A more signiifcant model of concrete resistance to sulfate attack was also established, thus this work provided a strategy reference for quantitative design of sulfate attack resistant concrete. The experimental results show that dry-wet cycle deteriorates the concrete resistance to the sulfate attack, and leads to the remarkable declines of concrete strength and sulfate resistance. Air bubbles in the air-entrained silica fume concrete lower and delay the damage resulted from the crystallization sulfate salt. However this delay gradually disappears when most of the close bubbles are breached by the alternative running of the sulfate salt crystallization and the permeating pressure, and then the air bubbles are iflled with sulfate salt crystallization. The concrete is provided with the strongest sulfate resistance when it is prepared with the 0.47 water-binder ratio, 6.0% air-entrained, 5% silica fume and 30% sand ratio. The erosion resistant coefifcientsK80 andK150 of this concrete are increased by 9%, 7%, 9%, and 5% respectively as compared with those of concretes without silica fume and air entraining.

  14. Dry air effects on the copper oxides sensitive layers formation for ethanol vapor detection

    Energy Technology Data Exchange (ETDEWEB)

    Labidi, A., E-mail: Ahmed_laabidi@yahoo.fr [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia); Bejaoui, A.; Ouali, H. [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia); Akkari, F. Chaffar [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs, ENIT, Universite de Tunis el Manar, BP 37, Le belvedere 1002, Tunis (Tunisia); Hajjaji, A.; Gaidi, M. [Laboratoire de Photovoltaique, Centre de Recherches et de technologies de l' energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia); Kanzari, M. [Laboratoire de Photovoltaique et Materiaux Semi-conducteurs, ENIT, Universite de Tunis el Manar, BP 37, Le belvedere 1002, Tunis (Tunisia); Bessais, B. [Laboratoire de Photovoltaique, Centre de Recherches et de technologies de l' energie, Technopole de Borj-Cedria, BP 95, 2050 Hammam-Lif (Tunisia); Maaref, M. [URPSC (UR 99/13-18) Unite de Recherche de Physique des Semiconducteurs et Capteurs, IPEST, Universite de Carthage, BP 51, La Marsa 2070, Tunis (Tunisia)

    2011-09-15

    The copper oxide films have been deposited by thermal evaporation and annealed under ambient air and dry air respectively, at different temperatures. The structural characteristics of the films were investigated by X-ray diffraction. They showed the presences of two hydroxy-carbonate minerals of copper for annealing temperatures below 250 deg. C. Above this temperature the conductivity measurements during the annealing process, show a transition phase from metallic copper to copper oxides. The copper oxides sensitivity toward ethanol were performed using conductivity measurements at the working temperature of 200 deg. C. A decrease of conductivity was observed under ethanol vapor, showing the p-type semi-conducting characters of obtained copper oxide films. It was found that the sensing properties of copper oxide toward ethanol depend mainly on the annealing conditions. The best responses were obtained with copper layers annealed under dry air.

  15. Dry air effects on the copper oxides sensitive layers formation for ethanol vapor detection

    International Nuclear Information System (INIS)

    The copper oxide films have been deposited by thermal evaporation and annealed under ambient air and dry air respectively, at different temperatures. The structural characteristics of the films were investigated by X-ray diffraction. They showed the presences of two hydroxy-carbonate minerals of copper for annealing temperatures below 250 deg. C. Above this temperature the conductivity measurements during the annealing process, show a transition phase from metallic copper to copper oxides. The copper oxides sensitivity toward ethanol were performed using conductivity measurements at the working temperature of 200 deg. C. A decrease of conductivity was observed under ethanol vapor, showing the p-type semi-conducting characters of obtained copper oxide films. It was found that the sensing properties of copper oxide toward ethanol depend mainly on the annealing conditions. The best responses were obtained with copper layers annealed under dry air.

  16. Soil air CO2 concentration as an integrative parameter of soil structure

    Science.gov (United States)

    Ebeling, Corinna; Gaertig, Thorsten; Fründ, Heinz-Christian

    2015-04-01

    The assessment of soil structure is an important but difficult issue and normally takes place in the laboratory. Typical parameters are soil bulk density, porosity, water or air conductivity or gas diffusivity. All methods are time-consuming. The integrative parameter soil air CO2 concentration ([CO2]) can be used to assess soil structure in situ and in a short time. Several studies highlighted that independent of soil respiration, [CO2] in the soil air increases with decreasing soil aeration. Therefore, [CO2] is a useful indicator of soil aeration. Embedded in the German research project RÜWOLA, which focus on soil protection at forest sites, we investigated soil compaction and recovery of soil structure after harvesting. Therefore, we measured soil air CO2 concentrations continuously and in single measurements and compared the results with the measurements of bulk density, porosity and gas diffusivity. Two test areas were investigated: At test area 1 with high natural regeneration potential (clay content approx. 25 % and soil-pH between 5 and 7), solid-state CO2-sensors using NDIR technology were installed in the wheel track of different aged skidding tracks in 5 and 10 cm soil depths. At area 2 (acidic silty loam, soil-pH between 3.5 and 4), CO2-sensors and water-tension sensors (WatermarkR) were installed in 6 cm soil depth. The results show a low variance of [CO2] in the undisturbed soil with a long term mean from May to June 2014 between 0.2 and 0.5 % [CO2] in both areas. In the wheel tracks [CO2] was consistently higher. The long term mean [CO2] in the 8-year-old-wheel track in test area 1 is 5 times higher than in the reference soil and shows a high variation (mean=2.0 %). The 18-year-old wheel track shows a long-term mean of 1.2 % [CO2]. Furthermore, there were strong fluctuations of [CO2] in the wheel tracks corresponding to precipitation and humidity. Similar results were yielded with single measurements during the vegetation period using a portable

  17. Application of the biological forced air soil treatment (BIOFAST trademark) technology to diesel contaminated soil

    International Nuclear Information System (INIS)

    A subsurface Biological Forced Air Soil Treatment (BIOFAST trademark) system was constructed at the Yellow Freight System, Inc. (Yellow Freight) New Haven facility in Connecticut as a means of expediting the remediation of soils impacted by a diesel fuel release. Prior to beginning construction activities the soils were evaluated for the feasibility of bioremediation based on soil characteristics including contaminant degrading bacteria, moisture content, and pH. Based on results of stimulant tests with oxygen and nutrients, the addition of fertilizer during the construction of the cell was recommended. Following the removal of underground storage tanks, the bioremediation cell was constructed by lining the enlarged excavation with high density polyethylene (HDPE) and backfilling alternating layers of nutrient-laden soil and pea gravel. Passive and active soil vapor extraction (SVE) piping was included in the gravel layers and connected to a blower and vapor treatment unit, operated intermittently to supply oxygen to the subsurface cell. Operating data have indicated that the bacteria are generating elevated levels of CO2, and the SVE unit is evacuating the accumulated CO2 from the soils and replacing it with fresh air. These data suggest that the bioremediation process is active in the soils. Soil samples collected from within the soil pit subsequent to installation and again after 10 months of operation indicate that TPH concentrations have decreased by as much as 50%

  18. External exposure to radionuclides in air, water, and soil

    International Nuclear Information System (INIS)

    Federal Guidance Report No. 12 tabulates dose coefficients for external exposure to photons and electrons emitted by radionuclides distributed in air, water, and soil. The dose coefficients are intended for use by Federal Agencies in calculating the dose equivalent to organs and tissues of the body

  19. Radioecological investigations in the food-chain air-soil-vine-wine. Pt. 1

    International Nuclear Information System (INIS)

    In a field investigation (1983-1985) comprising 8 locations of the most important viticultural regions in Germany, the contents of H-3, C-14, Sr-90, and Cs-137 in air, soils, leaves of the vine, grapes and wine were measured and site-specific transfer factors were calculated. Data concerning soil parameters, climatic conditions, cultivation and vinification were collected. The T contents of all samples were 10 Bq/l water of combustion, independent of location and year. The specific activity of C-14 in the atmosphere and in biological material was 0.22 Bq/g C, independent of site and year. Sr-90 contents of soils fluctuated between 0.7 and 3.5 Bq/kg dry matter. The mean content of leaves was 2 Bq/kg fresh material, of grapes 0.035 Bq/kg and of wine 0.008 Bq/l. The Cs-137 level of soils fluctuated between 1.3 and 7.9 Bq/kg dry matter. The mean content of leaves was 0.098 Bq/kg fresh material, of grapes 0.021 Bq/kg and of wine 0.0085 Bq/l. A relation between transfer and soil parameters and between the contents of grapes and wine was not recognizeable. While cultivar-specific differences were not observed in grapes, red wines contained somewhat more Cs-137 than white wines. Transfer factors soil-grapes were 0.027 for Sr-90 and 0.0057 for Cs-137. Site-specific influences such as soil parameters, climate, cultivation, vinification and differences between years led to a small fluctuation of values. No influence of the Neckarwestheim reactor has been found in any of the radionuclides. (orig./HP)

  20. Influence of Various Air Temperature on Duration of Drying Pumpkin Seed with Higher Water Content After Washing (Cucurbita pepo L.

    Directory of Open Access Journals (Sweden)

    S. Sito

    1998-12-01

    The samples dried at air temperature of 80 and 100°C were partly roasted, the seeds were dark coloured (burned, inferior taste, and problematic storage quality. Consequently air temperature above 60°C could not be recommended for pumpkin seed drying.

  1. Microbial Biomass C,N and P in Disturbed Dry Tropical Forest Soils, India

    Institute of Scientific and Technical Information of China (English)

    J.S.SINGH; D.P.SINGH; A.K.KASHYAP

    2010-01-01

    Variations in microbial biomass C(MB-C),N(MB-N)and P(MB-P)along a gradient of different dominant vegetation covers(natural forest,mixed deciduous forest,disturbed savanna and grassland ecosystems)in dry tropical soils of Vindhyan Plateau,India were studied from January 2005 to December 2005.The water holding capacity,organic C,total N,total P and soil moisture content were comparatively higher in forest soils than in the savanna and grassland sites.Across different study sites the mean annual MB-C,MB-N and MB-P at 0-15 cm soil depth varied from 312.05 ± 4.22to 653.40 ± 3.17,32.16 ± 6.25 to 75.66 ± 7.21 and 18.94 ± 2.94 to 30.83 ± 23.08 μg g-1 dry soil,respectively.At all the investigated sites,the maximum MB-C,MB-N and MB-P occurred during the dry period(summer season)and the minimum in wet period(rainy season).In the present study,soil MB-C,MB-N and MB-P were higher at the forest sites compared to savanna and grassland sites.The differences in MB-C,MB-N and MB-P were significant(P mixed deciduous forest > savanna > grassland.The results suggested that deforestation and land use practices(conversion of forest into savanna and grassland)caused the alterations in soil properties,which as a consequence,led to reduction in soil nutrients and MB-C,MB-N and MB-P in the soil of disturbed sites(grassland and savanna)compared to undisturbed forest ecosystems.

  2. New species of ice nucleating fungi in soil and air

    Science.gov (United States)

    Fröhlich-Nowoisky, Janine; Hill, Thomas C. J.; Pummer, Bernhard G.; Franc, Gray D.; Pöschl, Ulrich

    2014-05-01

    Primary biological aerosol particles (PBAP) are ubiquitous in the atmosphere (1,2). Several types of PBAP have been identified as ice nuclei (IN) that can initiate the formation of ice at relatively high temperatures (3, 4). The best-known biological IN are common plant-associated bacteria. The IN activity of these bacteria is due to a surface protein on the outer cell membrane that catalyses ice formation, for which the corresponding gene has been identified and detected by DNA analysis (3). Fungal spores or hyphae can also act as IN, but the biological structures responsible for their IN activity have not yet been elucidated. Furthermore, the abundance, diversity, sources, seasonality, properties, and effects of fungal IN in the atmosphere have neither been characterized nor quantified. Recent studies have shown that airborne fungi are highly diverse (1), and that atmospheric transport leads to efficient exchange of species among different ecosystems (5, 6). The results presented in Fröhlich-Nowoisky et al. 2012 (7) clearly demonstrate the presence of geographic boundaries in the global distribution of microbial taxa in air, and indicate that regional differences may be important for the effects of microorganisms on climate and public health. DNA analyses of aerosol samples collected during rain events showed higher diversity and frequency of occurrence for fungi belonging to the Sordariomycetes, than samples that were collected under dry conditions (8). Sordariomycetes is the class that comprises known ice nucleation active species (Fusarium spp.). By determination of freezing ability of fungal colonies isolated from air samples two species of ice nucleation active fungi that were not previously known as biological ice nucleators were found. By DNA-analysis they were identified as Isaria farinosa and Acremonium implicatum. Both fungi belong to the phylum Ascomycota, produce fluorescent spores in the range of 1-4 µm in diameter, and induced freezing at -4 and

  3. Effects of Temperature and Drying and Wetting Alternation on Ammonium Fixation in Manured Loessial Soil

    Institute of Scientific and Technical Information of China (English)

    FANXIAOLIN; LILING; 等

    1996-01-01

    Effects of temperature and drying and wetting alternation (DWA) on ammonium fixation in manured loessial soil were studied by means of Batch Equilibrium with varying concentration solutions of ammonium chloride.ammonium fixation time,and soil clay contents.The purpose of the research was to find out the pattern of ammonium fixation affected by the varying factors.The results showed a remarkable variation in ammonium fixation.Fixed ammonium increased with temperature and treatments of DWA.The ammonium fixation in manured loessial soil was characterized by the effect of temperature and DWA.

  4. Effect of air velocity on kinetics of thin layer carrot pomace drying.

    Science.gov (United States)

    Kumar, N; Sarkar, B C; Sharma, H K

    2011-10-01

    Carrot pomace is a by-product obtained during carrot juice processing. Thin layer carrot pomace drying was performed in a laboratory scale hot air forced convective dryer. The drying experiments were carried out at the air velocity of 0.5, 0.7 and 1.0 m/s at air temperatures from 60 to 75 °C. It was observed that whole drying process of carrot pomace took place in a falling rate period except a very short accelerating period at the beginning. Mathematical models were tested to fit drying data of carrot pomace. The best fit model was observed on the basis of R², Chi-square and RMSE values. R² values for all the selected models were above 0.9783. The average values of effective diffusivity ranged from 2.61 × 10(-9) to 3.64 × 10(-9) m²/s. PMID:21954311

  5. Mathematical Modeling of Hot Air Drying Kinetics of Momordica Charantia Slices and Its Color Change

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2013-09-01

    Full Text Available This study presented the drying characteristics of fresh Momordica Charantia slices at different drying temperatures (50, 60, 70 and 80°C and different thicknesses (0.5, 0.75 and 1.0 cm. Three mathematical models including Page, Henderson and Pabis and Wang and Singh equations were compared and discussed. The results showed that the Page model provided the best correlation capacity with the decision coefficient R2 of 0.998. The color change of Momordica Charantia slices during hot air drying at different temperatures were also studied by the measuring of color parameters such as the values of Hunter L* (whiteness/darkness, a* (redness/greenness and b* (yellowness/blueness. The total color change (ΔE of the samples was observed to increase as drying temperature increased. The results show that the color ofMomordica Charantia slices changed sharply when temperature was higher than about 70°C. The study could provide theoretical bases of the equipment design and process optimization for hot air drying of Momordica Charantia

  6. Microbiological and sensory evaluation of Jambu (Acmella oleracea L. dried by cold air circulation

    Directory of Open Access Journals (Sweden)

    Alan Franco BARBOSA

    2016-01-01

    Full Text Available Abstract The aim of this study was to evaluate the microbiological and sensory quality of the Jambu (Acmella oleracea L. in natura and dried by cold air, and the determination of its drying curve. The microbiological analysis were performed to Salmonella spp, the coagulase-positive Staphylococcus, and coliforms in the both Jambu samples, at 45 °C. Tacacá, the typical food dish of Pará state, Brazil, has showed good consumer global acceptance in the sensory evaluation of Jambu in natura (score of 8.00 ± 1.46 and dried (score of 8.67 ± 0.66. Both samples, Jambu in natura and dried by cold air, were by the current legislation regarding the microbiological aspects, this is the absence of Salmonella spp, coagulase-positive Staphylococcus <1×101 CFU/g, and coliforms <3 MPN/g, at 45 °C. Thus, considering sensory and health aspects, the commercialization of dried Jambu becomes viable, facilitating its transportation and handling, as well as for reducing its vegetable mass.

  7. STATISTIC MODELING OF DRYING KINETHIC OF SPINACH LEAVES USING MICROWAVE AND HOT AIR METHODS

    OpenAIRE

    Mojtaba Nouri; Marzieh Vahdani; Shilan Rashidzadeh; Lukáš Hleba; Mohammad Ali Shariati

    2015-01-01

    The target of this study was to model of spinach leaves drying using microwave and hot air dryer. This test performed in combination treatment of temperatures (50°C, 60°C, and 70°C) and microwave (90, 180, 360, 600 and 900w) in 3 replications. Sample moisture measured within drying. All the results were fitted and analyzed with 8 mathematical models base on 3 parameters including determination (R2), Chi square(X2), root mean square errors(RSME). Results also revealed that temperature and micr...

  8. Mathematical Modeling of Hot Air Drying Kinetics of Momordica Charantia Slices and Its Color Change

    OpenAIRE

    Jie Chen; Ying Zhou; Sheng Fang; Yuecheng Meng; Xin Kang; Xuejiao Xu; Xiaobo Zuo

    2013-01-01

    This study presented the drying characteristics of fresh Momordica Charantia slices at different drying temperatures (50, 60, 70 and 80°C) and different thicknesses (0.5, 0.75 and 1.0 cm). Three mathematical models including Page, Henderson and Pabis and Wang and Singh equations were compared and discussed. The results showed that the Page model provided the best correlation capacity with the decision coefficient R2 of 0.998. The color change of Momordica Charantia slices during hot air dryin...

  9. A novel method for air drying aloe leaf slices by covering with filter papers as a shrink-proof layer.

    Science.gov (United States)

    Kim, S A; Baek, J H; Lee, S J; Choi, S Y; Hur, W; Lee, S Y

    2009-01-01

    To prevent the shrinkage of aloe vera slices during air drying, a method utilizing a shrink-proof layer was developed. The sample was configured of whole leaf aloe slices, where 1 side or both sides were covered with filter papers as shrink-proof layers. After air drying by varying the air temperature and the slice thickness, the drying characteristics, as well as several quality factors of the dried aloe vera leaf slices, were analyzed. In the simulation of the drying curves, the modified Page model showed the best fitness, representing a diffusion-controlled drying mechanism. Nonetheless, there was a trace of a constant-rate drying period in the samples dried by the method. Shrinkage was greatly reduced, and the rehydration ratios increased by approximately 50%. Scanning electron microscopic analysis revealed that the surface structure of original fibrous form was well sustained. FT-IR characteristics showed that the dried samples could sustain aloe polysaccharide acetylation. Furthermore, the functional properties of the dried slices including water holding capacity, swelling, and fat absorption capability were improved, and polysaccharide retention levels increased by 20% to 30%. Therefore, we concluded that application of shrink-proof layers on aloe slices provides a novel way to overcome the shrinkage problems commonly found in air drying, thereby improving their functional properties with less cost. Practical Application: This research article demonstrates a novel air drying method using shrink-proof layers to prevent the shrinkage of aloe slices. We analyzed extensively the characteristics of shrinkage mechanism and physical properties of aloe flesh gels in this drying system. We concluded that this method can be a beneficial means to retain the functional properties of dried aloe, and a potential alternative to freeze drying, which is still costly. PMID:20492108

  10. The effect of soil surface sealing on vegetation water uptake along a dry climatic gradient

    Science.gov (United States)

    Sela, Shai; Svoray, Tal; Assouline, Shmuel

    2015-09-01

    Soil surface sealing is a widespread natural process occurring frequently in bare soil areas between vegetation patches. The low hydraulic conductivity that characterizes the seal layer reduces both infiltration and evaporation fluxes from the soil, and thus has the potential to affect local vegetation water uptake (VWU). This effect is investigated here using experimental data, 2-D physically based modeling, and a long-term climatic data set from three dry sites presenting a climatic gradient in the Negev Desert, Israel. The Feddes VWU parameters for the dominant shrub at the study site (Sarcopoterium spinosum) were acquired using lysimeter experiments. The results indicate that during the season surface sealing could either increase or decrease VWU depending on initial soil water content, rainfall intensity, and the duration of the subsequent drying intervals. These factors have a marked effect on interannual variability of the seal layer effect on VWU, which on average was found to be 26% higher under sealed conditions than in the case of unsealed soil surfaces. The seal layer was found to reduce the period where the vegetation was under water stress by 31% compared with unsealed conditions. This effect was more pronounced for seasons with total rainfall depth higher than 10 cm/yr, and was affected by interseasonal climatic variability. These results shed light on the importance of surface sealing in dry environments and its contribution to the resilience of woody vegetation.

  11. Modeling Soil Water in the Caatinga Tropical Dry Forest of Northeastern Brazil

    Science.gov (United States)

    Wright, C.; Wilcox, B.; Souza, E.; Lima, J. R. D. S.; West, J. B.

    2015-12-01

    The Caatinga is a tropical dry forest unique to northeastern Brazil. It has a relatively high degree of endism and supports a population of about 20 million subsistence farmers. However, it is poorly understood, under-researched and often over-looked in regards to other Brazilian ecosystems. It is a highly perturbed system that suffers from deforestation, land use change, and may be threatened by climate change. How these perturbations affect hydrology is unknown, but may have implications for biodiversity and ecosystem services and resiliency. Therefore, understanding key hydrological processes is critical, particularly as related to deforestation. In this study, Hydrus 1D, which is based on van Genuchten parameters to describe the soil water curve and Richard's Equation to describe flow in the vadose zone, was used to model soil moisture in the Caatinga ecosystem. The aim was 1) to compare hydraulic characterization between a forested Caatinga site and a deforested pasture site, 2) to analyze inter-annual variability, and 3) to compare with observed soil moisture data. Hydraulic characterization included hydraulic conductivity, infiltration, water content and pressure head trends. Van Genuchten parameters were derived using the Beerkan method, which is based on soil texture, particle distribution, as well as in-situ small-scale infiltration experiments. Observational data included soil moisture and precipitation logged every half-hour from September 2013 to April 2014 to include the dry season and rainy season. It is expected that the forested Caatinga site will have a higher hydraulic conductivity as well as retain higher soil moisture values. These differences may be amplified during the dry season, as water resources become scarce. Deviations between modeled data and observed data will allow for further hypothesis to be proposed, especially those related to soil water repellency. Hence, these results may indicate difference in soil water dynamics between a

  12. Gas Transport Parameters for Landfill Final Cover Soil: Measurements and Model Modification by Dry Bulk Density

    Science.gov (United States)

    Wickramarachchi, P. N.; Kawamoto, K.; Hamamoto, S.; Nagamori, M.; Moldrup, P.; Komatsu, T.

    2011-12-01

    Landfill sites have been emerging in greenhouse warming scenarios as a significant source of atmospheric methane (CH4). Until recently, landfill management strategies have mainly addressed the problem of preventing groundwater contamination and reduction of leachate generation. Being one of the largest sources of anthropogenic CH4 emission, the final cover system should also be designed for minimizing the greenhouse gases migration into the atmosphere or the areas surrounding the landfill while securing the hydraulic performance. Compared to the intensive research efforts on hydraulic performances of landfill final cover soil, few studies about gas transport characteristics of landfill cover soils have been done. However, recent soil-gas studies implied that the effects of soil physical properties such as bulk density (i.e., compaction level), soil particle size are key parameters to understand landfill gaseous performance. The gas exchange through the final cover soils is controlled by advective and diffusive gas transport. Air permeability (ka) governs the advective gas transport while the soil-gas diffusion coefficient (Dp) governs diffusive gas transport. In this study, the effects of compaction level and particle size fraction effects on ka and Dp for landfill final cover soil was investigated. The disturbed soil samples were taken from landfill final cover in Japan. A compaction tests were performed for the soil samples with two different size fractions (landfill final cover soil.

  13. Impact of drying-rewetting events on the response of soil microbial functions to dairyfibre and Miscanthus biochars

    Science.gov (United States)

    Bonnett, Sam; Vink, Stefanie; Baker, Kate; Saghir, Muhammad; Hornung, Andreas

    2014-05-01

    Biochar application has been shown to positively affect soil microbial functions such as reducing greenhouse gas emissions, increasing water/nutrient availability and increasing crop yields in tropical regions (Lehmann & Joseph, 2009). Understanding the dynamics of biochar application to soil microbial processes is critical for ensuring that soil quality, integrity and sustainability of the soil sub-system are maintained for crop growth. The aim of this British Ecological Society (BES) funded study was to examine the effect of two types of biochar on soil physicochemistry, GHG production, soil enzyme activities and microbial biomass in typical agricultural soil types and whether the effects were altered by drying, rewetting and flooding events. Miscanthus and dairyfibre (a mixture of straw and manure) feedstocks from Harper Adams University were pyrolyzed by Aston University at 450 °C using 100 kg/hr pyroformer technology. Two sieved soil types (sandy loam and clay loam) were mixed with dry biochar to produce 2 and 10 % w/w treatments for comparison with controls and maintained at 15 °C in temperature controlled incubators. At 0, 22, 44, 80, 101, and 114 days, soil was collected for determination of heterotrophic respiration, and microbial biomass by substrate-induced respiration (SIR), by gas headspace incubation and analysis of carbon dioxide (CO2) and nitrous oxide (N2O) by gas chromatography. Soil was sampled for the determination of water-extractable carbon, pH, and extracellular enzyme activities. Soil samples were maintained at field gravimetric water content between 0 and 44 days; air dried between 44 and 80 days; rewetted between 80 and 101 days; and flooded between 101 to 114 days. Results showed that the impact of biochar on soil microbial processes was dependent on biochar type and soil type, the level of biochar application and changes in soil moisture. Biochar affected soil pH particularly within the dairyfibre treatments, potentially due to the

  14. Evaluation of background soil and air polychlorinated biphenyl (PCB) concentrations on a hill at the outskirts of a metropolitan city.

    Science.gov (United States)

    Kuzu, S Levent; Saral, Arslan; Güneş, Gülten; Karadeniz, Aykut

    2016-07-01

    Air and soil sampling was conducted inside a forested area for 22 months. The sampling location is situated to the north of a metropolitan city. Average atmospheric gas and particle concentrations were found to be 180 and 28 pg m(-3) respectively, while that of soil phase was detected to be 3.2 ng g(-1) on dry matter, The congener pairs of PCB#4-10 had the highest contribution to each medium. TEQ concentration was 0.10 pg m(-3), 0.07 pg m(-3), 21.92 pg g(-1), for gas, particle and soil phases, respectively. PCB#126 and PCB#169 contributed to over 99% of the entire TEQ concentrations for each medium. Local sources were investigated by conditional probability function (CPF) and soil/air fugacity. Landfilling area and medical waste incinerator, located to the 8 km northeast, contributed to ambient concentrations, especially in terms of dioxin-like congeners. The industrial settlement (called Dilovasi being to the east southeast of 60 km distant) contributed from southeast direction. Further sources were identified by potential source contribution function (PSCF). Sources at close proximity had high contribution. Air mass transportation from Aliaga industrial region (being to the southwest of 300 km distant) moderately contributed to ambient concentrations. Low molecular weight congeners were released from soil body. 5-CBs and 6-CBs were close to equilibrium state between soil/air interfaces. PCB#171 was close to equilibrium and PCB#180 was likely to evaporate from soil, which constitute 7-CBs. PCB#199, representing 8-CBs deposited to soil. 9-CB (PCB#207) was in equilibrium between soil and air phases. PMID:27038903

  15. Volume reduction of radiocesium-contaminated soil by air-lift washing process. Demonstration studies in Iitate and Kawauchi village

    International Nuclear Information System (INIS)

    A small system was developed for volume reduction of radiocesium-contaminated soils. Included in this system was a 100-L air-lift washing chamber, a coagulation tank, and a dewatering apparatus. Soil samples (137Cs 6.2 x 103 - 1.9 x 104 Bq/kg) collected from a parking area in Iitate village, Fukushima Prefecture were put through this soil washing chamber. Results showed that 14-17% (dry weight) of the soil particles were ideally recovered with 75-86% of 137Cs (3.0 x 104 - 7.4 x 104 Bq/kg). Soil samples collected from an area with bamboo bushes, showed that 53-55% of the soil particle's weight were recovered with 87-89% of 137Cs (3.0 x 104 - 7.4 x 104 Bq/kg). Soil samples collected from a farm load and ditch in Kawauchi village (1.0 x 103 - 7.3 x 103 Bq/kg) were treated by soil washing, coagulation, and dewatering in series. Results showed that 10-14% weight of the soil particles were recovered as dewatered cake (4.4 x 103 - 3.1 x 104 Bq/kg) with only 43-46% of 137Cs. These results confirm soil-characteristic-dependency from the volume reduction efficiency of radiocesium-contaminated soils. (author)

  16. Influence of Disturbance on Soil Respiration in Biologically Crusted Soil during the Dry Season

    Directory of Open Access Journals (Sweden)

    Wei Feng

    2013-01-01

    Full Text Available Soil respiration (Rs is a major pathway for carbon cycling and is a complex process involving abiotic and biotic factors. Biological soil crusts (BSCs are a key biotic component of desert ecosystems worldwide. In desert ecosystems, soils are protected from surface disturbance by BSCs, but it is unknown whether Rs is affected by disturbance of this crust layer. We measured Rs in three types of disturbed and undisturbed crusted soils (algae, lichen, and moss, as well as bare land from April to August, 2010, in Mu Us desert, northwest China. Rs was similar among undisturbed soils but increased significantly in disturbed moss and algae crusted soils. The variation of Rs in undisturbed and disturbed soil was related to soil bulk density. Disturbance also led to changes in soil organic carbon and fine particles contents, including declines of 60–70% in surface soil C and N, relative to predisturbance values. Once BSCs were disturbed, Q10 increased. Our findings indicate that a loss of BSCs cover will lead to greater soil C loss through respiration. Given these results, understanding the disturbance sensitivity impact on Rs could be helpful to modify soil management practices which promote carbon sequestration.

  17. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    Institute of Scientific and Technical Information of China (English)

    J.P.SARRETTE; O.EICHWALD; F.MARCHAL; O.DUCASSE; M.YOUSFI

    2016-01-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply.The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz.The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air).The simulation involves the electro-dynamics,chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation.Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond.The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO.After 5 ms,the time corresponding to the occurrence of 50 successive discharge/post-discharge phases,a higher NO removal rate and a lower ozone production rate are found in humid air.This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  18. Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges

    Science.gov (United States)

    P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.

    2016-05-01

    The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.

  19. Study on Longitudinal Gas Permeability of Air-dried Masson Pine Sapwood

    Institute of Scientific and Technical Information of China (English)

    HOU Zhuqiang; ZHANG Lifei; GUAN Ning; CHEN Guihua

    2006-01-01

    Measurement of the longitudinal gas permeability was made for air-dried sapwood specimens from Masson pine(Pinus massoniana).Results showed that air-dried Masson pine sapwood was one of the most permeable softwoods.The investigated specimens had an average longitudinal gas permeability of 4.60 ×10-13m3/m.and the permeability ranged from 1.06×10-13 to 1.12 ×10-12m3/m.The Kruskal-Wallis Test indicated that,generally,there was no correlation between the longitudinal gas permeability and the trees from which specimens were prepared,and tree height had no significant effect on the longitudinal gas permeability.

  20. Influence of Dry Soil on the Ability of Formosan Subterranean Termites, Coptotermes formosanus, to Locate Food Sources

    OpenAIRE

    Mary L. Cornelius; Weste L.A. Osbrink

    2011-01-01

    The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three—chambered apparatus were compared between treatments with dry soil in the center container and treatments where the soil in the center container was moist. When a wood block was located in the release container, termites fed significantly more on that b...

  1. Induction of Soil Suppressiveness Against Rhizoctonia solani by Incorporation of Dried Plant Residues into Soil.

    Science.gov (United States)

    Kasuya, Masahiro; Olivier, Andriantsoa R; Ota, Yoko; Tojo, Motoaki; Honjo, Hitoshi; Fukui, Ryo

    2006-12-01

    ABSTRACT Suppressive effects of soil amendment with residues of 12 cultivars of Brassica rapa on damping-off of sugar beet were evaluated in soils infested with Rhizoctonia solani. Residues of clover and peanut were tested as noncruciferous controls. The incidence of damping-off was significantly and consistently suppressed in the soils amended with residues of clover, peanut, and B. rapa subsp. rapifera 'Saori', but only the volatile substance produced from water-imbibed residue of cv. Saori exhibited a distinct inhibitory effect on mycelial growth of R. solani. Nonetheless, disease suppression in such residue-amended soils was diminished or nullified when antibacterial antibiotics were applied to the soils, suggesting that proliferation of antagonistic bacteria resident to the soils were responsible for disease suppression. When the seed (pericarps) colonized by R. solani in the infested soil without residues were replanted into the soils amended with such residues, damping-off was suppressed in all cases. In contrast, when seed that had been colonized by microorganisms in the soils containing the residues were replanted into the infested soil, damping-off was not suppressed. The evidence indicates that the laimosphere, but not the spermosphere, is the site for the antagonistic microbial interaction, which is the chief principle of soil suppressiveness against Rhizoctonia damping-off. PMID:18943670

  2. Influence of drying air parameters on mass transfer characteristics of apple slices

    Science.gov (United States)

    Beigi, Mohsen

    2015-12-01

    To efficiently design both new drying process and equipment and/or to improve the existing systems, accurate values of mass transfer characteristics are necessary. The present study aimed to investigate the influence of drying air parameters (i.e. temperature, velocity and relative humidity) on effective diffusivity and convective mass transfer coefficient of apple slices. The Dincer and Dost model was used to determine the mass transfer characteristics. The obtained Biot number indicated that the moisture transfer in the apple slices was controlled by both internal and external resistance. The effective diffusivity and mass transfer coefficient values obtained to be in the ranges of 7.13 × 10-11-7.66 × 10-10 and 1.46 × 10-7-3.39 × 10-7 m s-1, respectively and the both of them increased with increasing drying air temperature and velocity, and decreasing relative humidity. The validation of the model showed that the model predicted the experimental drying curves of the samples with a good accuracy.

  3. Carbon balance of surfaces vs. ecosystems: advantages of measuring eddy covariance and soil respiration simultaneously in dry grassland ecosystems

    Science.gov (United States)

    Nagy, Z.; Pintér, K.; Pavelka, M.; Darenová, E.; Balogh, J.

    2011-02-01

    An automated open system for measurement of soil CO2 efflux (Rsc) was developed and calibrated against known fluxes and tested in the field, while measuring soil respiration also by the gradient method (Rsg) at a dry sandy grassland (Bugac, Hungary). Ecosystem respiration (Reco) was measured by the eddy covariance technique. Small chamber size (5 cm in diameter) of the chamber system made it possible to use the chambers also in vegetation gaps, thereby avoiding the necessity of removing shoots, the disturbance of the spatial structure of vegetation and the upper soil layer. Low air flow rates associated with small chamber volume and chamber design allowed the overpressure range to stabilize between 0.05-0.12 Pa. While the correlation between ecosystem and soil CO2 efflux rates as measured by the independent methods was significant, Reco rates were similar or even lower than Rsc in the low flux (up to 2 μmol CO2 m-2 s-1) range, probably due to the larger than assumed storage flux. The gradient method showed both up and downward CO2 fluxes originating from the main rooting zone after rains. Downward fluxes within the soil profile amounted to 15% of the simultaneous upward fluxes and to ~ 7.6% of the total (upward) effluxes during the 3 months study. The upper 5 cm soil layer contributed to ~ 50% of the total soil CO2 efflux. The continuously operated automatic open chamber system and the gradient system makes possible the detection of situations when the eddy system underestimates Reco, gives the lower limit of underestimation (chamber system) and helps in quantifying the downward flux component of soil respiration (gradient method) between the soil layers. These latter (downward) fluxes are expected to seriously affect (1) the Reco vs. temperature response functions and (2) the net ecosystem exchange of CO2 (NEE) vs. photon flux density response functions, therefore potentially affecting also the gap filling procedures and to led to a situation (3) when the

  4. Chemistry and Mineralogy of Antarctica Dry Valley Soils: Implications for Mars

    Science.gov (United States)

    Quinn, J. E.; Golden, D. C.; Graff, T. G.; Ming, D. W.; Morris, R. V.; Douglas, S.; Kounaves, S. P.; McKay, C. P.; Tamppari, L, K.; Smith, P. H.; Zent, A. P.; Archer, P. D., Jr.

    2011-01-01

    The Antarctic Dry Valleys (ADV) comprise the largest ice-free region of Antarctica. Precipitation almost always occurs as snow, relative humidity is frequently low, and mean annual temperatures are about -20 C. The ADV soils have previously been categorized into three soil moisture regimes: subxerous, xerous and ultraxerous, based on elevation and climate influences. The subxerous regime is predominately a coastal zone soil, and has the highest average temperature and precipitation, while the ultraxerous regime occurs at high elevation (>1000 m) and have very low temperature and precipitation. The amounts and types of salts present in the soils vary between regions. The nature, origin and significance of salts in the ADV have been previously investigated. Substantial work has focused on soil formation in the ADVs, however, little work has focused on the mineralogy of secondary alteration phases. The dominant weathering process in the ADV region is physical weathering, however, chemical weathering has been well documented. The objective of this study was to characterize the chemistry and mineralogy, including the alteration mineralogy, of soils from two sites, a subxerous soil in Taylor Valley, and an ultraxerous soil in University Valley. The style of aqueous alteration in the ADVs may have implications for pedogenic processes on Mars.

  5. Using Artificial Soil and Dry-Column Flash Chromatography to Simulate Organic Substance Leaching Process: A Colorful Environmental Chemistry Experiment

    Science.gov (United States)

    de Avellar, Isa G. J.; Cotta, Tais A. P. G.; Neder, Amarilis de V. Finageiv

    2012-01-01

    Soil is an important and complex environmental compartment and soil contamination contributes to the pollution of aquifers and other water basins. A simple and low-cost experiment is described in which the mobility of three organic compounds in an artificial soil is examined using dry-column flash chromatography. The compounds were applied on top…

  6. A Numerical Assessment of the Air Flow Behaviour in a Conventional Compact Dry Kiln

    Directory of Open Access Journals (Sweden)

    Paulo Zdanski

    2015-01-01

    Full Text Available Convective drying is the most common drying strategy used in timber manufacturing industries in the developing world. In convective drying, the reduction rate of the moisture content is directly affected by the flow topology in the inlet and exit plenums and the air flow velocity in the channels formed by timber layers.Turbulence, boundary layer separation, vortex formation and recirculation regions are flow features that are intrinsically associated with the kiln geometry, which in turn dictate the flow velocity across the timber stack and, ultimately, the drying rate. Within this framework, this work presents a numerical study of the effects of the plenum width and inlet flow velocity in a compact dry kiln aiming to establish design recommendations to ensure the highest possible level of flow uniformity across the lumber stack. The numerical solution of the mathematical model is obtained through the finite-volume based Ansys CFX R flow solver. Validation of the numerical approximation is performed by comparing numerical and experimental flow velocities for a scale model of a kiln available in the literature.

  7. PAX8/PPARG and RET/PTC rearrangement detection is feasible in routine air dried fine needle aspiration (FNA) smears

    DEFF Research Database (Denmark)

    Ferraz, Carolina; Rehfeld, Christian; Krogdahl, Annelise;

    2012-01-01

    FNA smears could improve FNA diagnosis. To date, these rearrangements have never been analyzed in routine air-dried FNA smears, but only in frozen tissue, formalin-fixed paraffin-embedded (FFPE) tissue, and in fresh FNA material. Fixed routine air dried FNA samples have hitherto been judged as...... from routine air-dried FNA smears was established which allowed analysis for the presence of four variants of PAX8/PPARG and RET/PTC 1 and RET/PTC 3, which were analyzed in 106 routine FNA smears and the corresponding surgically obtained FFPE tissues using real time-qPCR (RT-qPCR). In order to assess...

  8. Atmospheric dry deposition in the vicinity of the Salton Sea, California - I: Air pollution and deposition in a desert environment

    Science.gov (United States)

    Alonso, R.; Bytnerowicz, A.; Boarman, W.I.

    2005-01-01

    Air pollutant concentrations and atmospheric dry deposition were monitored seasonally at the Salton Sea, southern California. Measurements of ozone (O 3), nitric acid vapor (HNO3), ammonia (NH3), nitric oxide (NO), nitrogen dioxide (NO2) and sulfur dioxide (SO 2) were performed using passive samplers. Deposition rates of NO 3-, NH4+, Cl-, SO 42-, Na+, K+ and Ca2+ to creosote bush branches and nylon filters as surrogate surfaces were determined for one-week long exposure periods. Maximum O3 values were recorded in spring with 24-h average values of 108.8 ??g m-3. Concentrations of NO and NO2 were low and within ranges of the non-urban areas in California (0.4-5.6 and 3.3-16.2 ??g m-3 ranges, respectively). Concentrations of HNO3 (2.0-6.7 ??g m-3) and NH 3 (6.4-15.7 ??g m-3) were elevated and above the levels typical for remote locations in California. Deposition rates of Cl-, SO42-, Na+, K+ and Ca2+ were related to the influence of sea spray or to suspended soil particles, and no strong enrichments caused by ions originated by human activities were detected. Dry deposition rates of NO3- and NH4+ were similar to values registered in areas where symptoms of nitrogen saturation and changes in species composition have been described. Deposition of nitrogenous compounds might be contributing to eutrophication processes at the Salton Sea. ?? 2005 Elsevier Ltd. All rights reserved.

  9. Influence of Air Temperature and Pretreatment Solutions on Drying Time, Energy Consumption and Organoleptic Properties of Sour Cherry

    Directory of Open Access Journals (Sweden)

    Hamid Reza Gazor

    2014-10-01

    Full Text Available The effects of pretreatment solution (no treatment, boiling water, salty boiling water, ethil oleat on drying time of sour cherry were studied experimentally. The thin layer drying of sour cherries was carried out at three air temperatures of 50, 60, 70°C and with constant airflow velocity of 1 m/s. Drying kinetic, energy consumption and organoleptic properties as taste, visual color and texture were evaluated in dried fruits. Results of experiments showed that pretreatment solutions and air temperatures had significant effect on drying time and organoleptic properties of dried sour cherry. Using of pretreatment solution is necessary before drying process. It reduced drying time up to 80% and energy saving was approximately 83% in comparison with no treatment samples. Results of this research indicated that using of salty boiling water as pretreatment and temperature of 50°C in sour cherry drying process cause the best result in drying time and organoleptic evaluation such as taste quality, visual color and texture suitability of dried fruit. In addition, energy consumption for drying reduced noticeably when sour cherry was pretreated with salty boiling water.

  10. Influence of Air Temperature and Pretreatment Solutions on Drying Time, Energy Consumption and Organoleptic Properties of Sour Cherry

    Directory of Open Access Journals (Sweden)

    Hamid Reza Gazor

    2014-09-01

    Full Text Available The effects of pretreatment solution (no treatment, boiling water, salty boiling water, ethil oleat on drying time of sour cherry were studied experimentally. The thin layer drying of sour cherries was carried out at three air temperatures of 50, 60, 70°C and with constant airflow velocity of 1 m/s. Drying kinetic, energy consumption and organoleptic properties as taste, visual color and texture were evaluated in dried fruits. Results of experiments showed that pretreatment solutions and air temperatures had significant effect on drying time and organoleptic properties of dried sour cherry. Using of pretreatment solution is necessary before drying process. It reduced drying time up to 80% and energy saving was approximately 83% in comparison with no treatment samples. Results of this research indicated that using of salty boiling water as pretreatment and temperature of 50°C in sour cherry drying process cause the best result in drying time and organoleptic evaluation such as taste quality, visual color and texture suitability of dried fruit. In addition, energy consumption for drying reduced noticeably when sour cherry was pretreated with salty boiling water.

  11. Morphological, sediment and soil chemical characteristics of dry tropical shallow reservoirs in the Southern Mexican Highlands

    Directory of Open Access Journals (Sweden)

    José Luis ARREDONDO-FIGUEROA

    2011-02-01

    Full Text Available The morphometry, sediment and soil chemical characteristics of eleven dry tropical shallow reservoirs situated in Southern Mexican Highlands were studied. The reservoirs are located at 1104 to 1183 meters above sea level in a sedimentary area. Seventeen morphometric and eight sediment and soil chemical parameters were measured. The results of the morphometric parameters showed that these reservoirs presented a soft and roughness bottom, with an ellipsoid form and a concave depression that permit the mix up of water and sediments, causing turbidity and broken thermal gradients; their slight slopes allowed the colonization of submerged macrophyte and halophyte plants and improved the incidence of sunlight on water surface increasing evaporation and primary productivity. Dry tropical shallow reservoirs have fluctuations in area, and volume according to the amount of rainfall, the effect of evaporation, temperature, lost volume for irrigation, and other causes. The sand-clay was the most important sediment texture and their values fluctuated with the flooded periods. The concentration-dilution cycle showed a direct relationship in the percentage of organic matter in the soil as well as with pH, soil nitrogen and phosphorus. El Tilzate, El Candelero and El Movil were related by the shore development and high concentrations of organic matter and nitrogen in the soil. Finally, we emphasize the importance of this study, in relation to possible future changes in morphometrical parameters as a consequence of human impact.

  12. GEMAS: Colours of dry and moist agricultural soil samples of Europe

    Science.gov (United States)

    Klug, Martin; Fabian, Karl; Reimann, Clemens

    2016-04-01

    High resolution HDR colour images of all Ap samples from the GEMAS survey were acquired using a GeoTek Linescan camera. Three measurements of dry and wet samples with increasing exposure time and increasing illumination settings produced a set of colour images at 50μm resolution. Automated image processing was used to calibrate the six images per sample with respect to the synchronously measured X-Rite colorchecker chart. The calibrated images were then fit to Munsell soil colours that were measured in the same way. The results provide overview maps of dry and moist European soil colours. Because colour is closely linked to iron mineralogy, carbonate, silicate and organic carbon content the results can be correlated to magnetic, mineralogical, and geochemical properties. In combination with the full GEMAS chemical and physical measurements, this yields a valuable data set for calibration and interpretation of visible satellite colour data with respect to chemical composition and geological background, soil moisture, and soil degradation. This data set will help to develop new methods for world-wide characterization and monitoring of agricultural soils which is essential for quantifying geologic and human impact on the critical zone environment. It furthermore enables the scientific community and governmental authorities to monitor consequences of climatic change, to plan and administrate economic and ecological land use, and to use the data set for forensic applications.

  13. Determination of Soil Water Content After Fallow, Winter and Spring Sown Lentil in Dry Farming Areas

    OpenAIRE

    ADAK, M. Sait

    2001-01-01

    This research was carried out from 1993 through 1995 for a two-year period in dry farming areas of Haymana/Ankara. The aim of the research was to determine the available water content of the 0-60 and 0-90 cm soil depth layers for wheat after fallow periods and after winter and spring crops of lentils under two different soil tillage treatments. According to the experimental results, the highest available water content was measured in fallow plots (28.6% (rototiller 0-60 cm) and 94.6% plough 0...

  14. Influence of material structure on air-borne ultrasonic application in drying.

    Science.gov (United States)

    Ozuna, César; Gómez Álvarez-Arenas, Tomás; Riera, Enrique; Cárcel, Juan A; Garcia-Perez, Jose V

    2014-05-01

    This work aims to contribute to the understanding of how the properties of the material being dried affect air-borne ultrasonic application. To this end, the experimental drying kinetics (40°C and 1m/s) of cassava (Manihot esculenta) and apple (Malus domestica var. Granny Smith) were carried out applying different ultrasonic powers (0, 6, 12, 19, 25 and 31 kW/m(3)). Furthermore, the power ultrasound-assisted drying kinetics of different fruits and vegetables (potato, eggplant, carrot, orange and lemon peel) already reported in previous studies were also analyzed. The structural, textural and acoustic properties of all these products were assessed, and the drying kinetics modeled by means of the diffusion theory. A significant linear correlation (r>0.95) was established between the identified effective diffusivity (DW) and the applied ultrasonic power for the different products. The slope of this relationship (SDUP) was used as an index of the effectiveness of the ultrasonic application; thus the higher the SDUP, the more effective the ultrasound application. SDUP was well correlated (r ⩾ 0.95) with the porosity and hardness. In addition, SDUP was largely affected by the acoustic impedance of the material being dried, showing a similar pattern with the impedance than the transmission coefficient of the acoustic energy on the interface. Thus, soft and open-porous product structures exhibited a better transmission of acoustic energy and were more prone to the mechanical effects of ultrasound. However, materials with a hard and closed-compact structure were less affected by acoustic energy due to the fact that the significant impedance differences between the product and the air cause high energy losses on the interface. PMID:24411471

  15. Relating trends in land surface-air temperature difference to soil moisture and evapotranspiration

    Science.gov (United States)

    Veal, Karen; Taylor, Chris; Gallego-Elvira, Belen; Ghent, Darren; Harris, Phil; Remedios, John

    2016-04-01

    Soil water is central to both physical and biogeochemical processes within the Earth System. Drying of soils leads to evapotranspiration (ET) becoming limited or "water-stressed" and is accompanied by rises in land surface temperature (LST), land surface-air temperature difference (delta T), and sensible heat flux. Climate models predict sizable changes to the global water cycle but there is variation between models in the time scale of ET decay during dry spells. The e-stress project is developing novel satellite-derived diagnostics to assess the ability of Earth System Models (ESMs) to capture behaviour that is due to soil moisture controls on ET. Satellite records of LST now extend 15 years or more. MODIS Terra LST is available from 2000 to the present and the Along-Track Scanning Radiometer (ATSR) LST record runs from 1995 to 2012. This paper presents results from an investigation into the variability and trends in delta T during the MODIS Terra mission. We use MODIS Terra and MODIS Aqua LST and ESA GlobTemperature ATSR LST with 2m air temperatures from reanalyses to calculate trends in delta T and "water-stressed" area. We investigate the variability of delta T in relation to soil moisture (ESA CCI Passive Daily Soil Moisture), vegetation (MODIS Monthly Normalized Difference Vegetation Index) and precipitation (TRMM Multi-satellite Monthly Precipitation) and compare the temporal and spatial variability of delta T with model evaporation data (GLEAM). Delta T anomalies show significant negative correlations with soil moisture, in different seasons, in several regions across the planet. Global mean delta T anomaly is small (magnitude mostly less than 0.2 K) between July 2002 and July 2008 and decreases to a minimum in early 2010. The reduction in delta T anomaly coincides with an increase in soil moisture anomaly and NDVI anomaly suggesting an increase in evapotranspiration and latent heat flux with reduced sensible heat flux. In conclusion there have been

  16. Zinc-phosphorus relationship in soils as measured by dry matter yield and plant analysis

    International Nuclear Information System (INIS)

    The effect of placement of P and Zn with seed on dry matter yield and absorption of these elements by barley was studied in three soils under controlled greenhouse conditions.Dry matter yield showed significant variation at 50 and 100 kg/ha levels of P but Zn effect was not significant. Total uptake of P and percent of P in plants derived from fertilizer did not significantly but utilization of fertilizer P and P content in plants differed significantly at two levels of P application. Uptake of Zn, percent Zn in plant derived from fertilizer and Zn content in plants differed significantly at 10 and 20 kg/ha levels of Zn application but utilization of fertilizer Zn did not differ. The placement of P and Zn together did not show any antagonism on their absorption by barley as well as on the A-values of soils. (author)

  17. Modeling evaporation processes in a saline soil from saturation to oven dry conditions

    Directory of Open Access Journals (Sweden)

    M. Gran

    2011-01-01

    Full Text Available Thermal, suction and osmotic gradients interact during evaporation from a salty soil. Vapor fluxes become the main water flow mechanism under very dry conditions. A coupled nonisothermal multiphase flow and a reactive transport model of a salty sand soil was developed to study such an intricate system. The model was calibrated with data from an evaporation experiment (volumetric water content, temperature and concentration. The retention curve and relative permeability functions were modified to simulate oven dry conditions. Experimental observations were satisfactorily reproduced, which suggests that the model can be used to assess the underlying processes. Results show that evaporation is controlled by heat, and limited by salinity and liquid and vapor fluxes. Below evaporation front vapor flows downwards controlled by temperature gradient and thus generates a dilution. Vapor diffusion and dilution are strongly influenced by heat boundary conditions. Gas diffusion plays a major role in the magnitude of vapor fluxes.

  18. Startup of air-cooled condensers and dry cooling towers at low temperatures of the cooling air

    Science.gov (United States)

    Milman, O. O.; Ptakhin, A. V.; Kondratev, A. V.; Shifrin, B. A.; Yankov, G. G.

    2016-05-01

    The problems of startup and performance of air-cooled condensers (ACC) and dry cooling towers (DCT) at low cooling air temperatures are considered. Effects of the startup of the ACC at sub-zero temperatures are described. Different options of the ACC heating up are analyzed, and examples of existing technologies are presented (electric heating, heating up with hot air or steam, and internal and external heating). The use of additional heat exchanging sections, steam tracers, in the DCT design is described. The need for high power in cases of electric heating and heating up with hot air is noted. An experimental stand for research and testing of the ACC startup at low temperatures is described. The design of the three-pass ACC unit is given, and its advantages over classical single-pass design at low temperatures are listed. The formation of ice plugs inside the heat exchanging tubes during the start-up of ACC and DCT at low cooling air temperatures is analyzed. Experimental data on the effect of the steam flow rate, steam nozzle distance from the heat-exchange surface, and their orientation in space on the metal temperature were collected, and test results are analyzed. It is noted that the surface temperature at the end of the heat up is almost independent from its initial temperature. Recommendations for the safe start-up of ACCs and DCTs are given. The heating flow necessary to sufficiently heat up heat-exchange surfaces of ACCs and DCTs for the safe startup is estimated. The technology and the process of the heat up of the ACC with the heating steam external supply are described by the example of the startup of the full-scale section of the ACC at sub-zero temperatures of the cooling air, and the advantages of the proposed start-up technology are confirmed.

  19. Absorbed dose rates in air due to U, Th and K in soils in parts of South-Western Nigeria

    International Nuclear Information System (INIS)

    The absorbed dose rates in air due to the presence of radioisotopes 40K, 238U and 252Th in soils in Ondo State, South Western Nigeria have been determined by first estimating the concentration of these radionuclides in the soils of the area. The concentrations of the radionuclide were measured using a multichannel pulse-height analyser connected to a 7.6 cm. x 7.6 cm. NaI(TI) detector and by the use of appropriate conversion factors, the absorbed dose rates in air, at a height of 1.0 m. above the ground were computed from the concentrations. The concentrations of the radioisotopes are expressed in BqKg1 of dry weight and the corresponding absorbed dose rates in air are expressed in nGyh-1 with mean of the acceptable International Commission on Radiological Protection (ICRP) dose limit

  20. Fire and soil temperatures during controlled burns in seasonally dry tropical forests of southern India

    OpenAIRE

    Mondal, Nandita; Sukumar, Raman

    2014-01-01

    Fire and soil temperatures were measured during controlled burns conducted by the Forest Department at two seasonally dry tropical forest sites in southern India, and their relationships with fuel load, fuel moisture and weather variables assessed using stepwise regression. Fire temperatures at the ground level varied between 79 degrees C and 760 degrees C, with higher temperatures recorded at high fuel loads and ambient temperatures, whereas lower temperatures were recorded at high relative ...

  1. Temporal stability of the apparent electrical conductivity measured in seasonally dry sandy soil

    Science.gov (United States)

    Pedrera, Aura; Brevik, Eric C.; Giráldez, Juan V.; Vanderlinden, Karl

    2016-04-01

    Soil is spatially heterogeneous due to differences in parent material, climate, topography, time and management practices. The use of non-invasive and non-contact geophysical methods facilitates the exploration of natural landscapes or cropped areas. Electromagnetic induction (EMI) sensors which measure the soil apparent electrical conductivity (ECa) express soil spatial variability in terms of spatial soil ECa variability. In an agricultural context, knowledge and understanding of the soil spatial variability will allow us to delimit areas where precision agriculture techniques could be used to improve management practices. These practices enhance soil and water conservation, especially for sandy soils in Mediterranean climates where soils are dry for substantial periods of time. The first objective of this work was to apply principal component analysis (PCA) to see if a temporally stable component could be found. The second objective was to see if temporal stability information acquired from several ECa surveys could be used to better interpret results of a single survey in terms of relationships between ECa and soil water content (SWC). The experimental catchment, "La Manga", is located in SW Spain and covers 6.7 ha of a rainfed olive orchard. Soil profile samples were collected at 41 locations on a pseudo-regular grid. Samples were analyzed in the laboratory for soil texture, stone content, and bulk density (ρb). The catchment was sampled for gravimetric SWC at the 0-0.1 and 0.1-0.2 m depth intervals at the same 41 locations on 18 occasions. At the same 41 locations ECa was measured during 9 of the 18 SWC surveys using a DUALEM-21S EMI sensor. In addition, 7 field-wide ECa surveys were conducted. Soil ECa values were used to delimit three areas in the orchard, based on the spatial distribution of the first principal component (PC), which represented the spatial ECa pattern. Soil properties were studied within each area, and using analysis of variance

  2. Entrainment Rate in Shallow Cumuli: Dependence on Entrained Dry Air Sources and Probability Density Functions

    Science.gov (United States)

    Lu, C.; Liu, Y.; Niu, S.; Vogelmann, A. M.

    2012-12-01

    In situ aircraft cumulus observations from the RACORO field campaign are used to estimate entrainment rate for individual clouds using a recently developed mixing fraction approach. The entrainment rate is computed based on the observed state of the cloud core and the state of the air that is laterally mixed into the cloud at its edge. The computed entrainment rate decreases when the air is entrained from increasing distance from the cloud core edge; this is because the air farther away from cloud edge is drier than the neighboring air that is within the humid shells around cumulus clouds. Probability density functions of entrainment rate are well fitted by lognormal distributions at different heights above cloud base for different dry air sources (i.e., different source distances from the cloud core edge). Such lognormal distribution functions are appropriate for inclusion into future entrainment rate parameterization in large scale models. To the authors' knowledge, this is the first time that probability density functions of entrainment rate have been obtained in shallow cumulus clouds based on in situ observations. The reason for the wide spread of entrainment rate is that the observed clouds are affected by entrainment mixing processes to different extents, which is verified by the relationships between the entrainment rate and cloud microphysics/dynamics. The entrainment rate is negatively correlated with liquid water content and cloud droplet number concentration due to the dilution and evaporation in entrainment mixing processes. The entrainment rate is positively correlated with relative dispersion (i.e., ratio of standard deviation to mean value) of liquid water content and droplet size distributions, consistent with the theoretical expectation that entrainment mixing processes are responsible for microphysics fluctuations and spectral broadening. The entrainment rate is negatively correlated with vertical velocity and dissipation rate because entrainment

  3. Mapping dry matter production of Tifton 85 and its correlation with the soil chemical properties

    Directory of Open Access Journals (Sweden)

    Osmar Henrique de Castro Pias

    2015-07-01

    Full Text Available The creation of cattle in the semi extensive system has currently been the most used by the farmers on Brazil, however, problems such as degradation of pastures are committing this production system, reducing the production of forager and consequently the profitability of producers. In this sense, the aim of this study was to perform the mapping of the dry mass production, nitrogen accumulation, phosphorus and potassium in the Tifton 85, and evaluate their correlations with the chemical attributes in different layers of the soil profile. The study was carried out in an area of 4.3 ha constituted of Tifton 85 in the city of Vista Gaucha - RS, Brazil, during the months from October to December in the year of 2012. The experimental area was georeferenced and divided into a sample mesh of 50 x 50 m, resulting in 16 sampling points. It was conducted two cuts on Tifton 85 to evaluate the dry mass production. Soil sampling was done in the layers from 0.00 - 0.10 m, 0.10 - 0.20 and 0.20 - 0.40 m. The data were submitted to descriptive statistical analysis and linear correlation matrix of Pearson, being the results specialized in thematic maps. The production of dry mass, nitrogen accumulation, phosphorus and potassium by Tifton 85 showed coefficients of variation ranked of high to very high, and in generally, demonstrated low correlation with the soil chemical properties, independently of the layer profile evaluated.

  4. Soil emissions of nitric oxide in a seasonally dry tropical forest of Mexico

    Science.gov (United States)

    Davidson, Eric A.; Vitousek, Peter M.; Riley, Ralph; Matson, Pamela A.; Garcia-Mendez, Georgina; Maass, J. M.

    1991-01-01

    Soil emissions of NO were measured at the Chamela Biological Station, Mexico, using soil covers and a field apparatus of NO detection based on CrO3 conversion of NO to NO2 and detection of NO2 by chemiluminescence with Luminol. Mean NO fluxes from forest soils ranged from 0.14 to 0.52 ng NO-N/sq cm/hr during the dry season and from 0.73 to 1.27 ng NO-N/sq cm/hr during the wet season. A fertilized floodplain pasture exhibited higher fluxes, but an unfertilized upland pasture, which represents the fastest growing land use in the region, had flux rates similar to the forest sites. Wetting experiments at the end of the dry season caused large pulses of NO flux, equaling 10 percent to 20 percent of the estimated annual NO emissions of 0.5-1.0 kg N/ha from the forest sites. Absence of a forest canopy during the dry season and the first wet season rain probably results in substantial NO(x) export from the forest system that may be important to regional atmospheric chemical processes. Wetting experiments during the wet season and a natural rain event had little or no stimulatory effect on NO flux rates.

  5. Regional Simulation of Soil Organic Carbon Dynamics for Dry Farmland in East China by Coupling a 1:500 000 Soil Database with the Century Model

    Institute of Scientific and Technical Information of China (English)

    WANG Shi-Hang; SHI Xue-Zheng; ZHAO Yong-Cun; D.C.WEINDORF; YU Dong-Sheng; XU Sheng-Xiang; TAN Man-Zhi; SUN Wei-Xia

    2011-01-01

    Changes in soil organic carbon (SOC) in agricultural soils influence soil quality and greenhouse gas concentrations in the atmosphere. Dry farmland covers more than 70% of the whole cropland area in China and plays an important role in mitigating carbon dioxide (CO2) emissions. In this study, 4 109 dry farmland soil polygons were extracted using spatial overlay analysis of the soil layer (1:500 000) and the land use layer (1:500 000) to support Century model simulations of SOC dynamics for dry farmland in Anhui Province, East China from 1980 to 2008. Considering two field-validation sites,the Century model performed relatively well in modeling SOC dynamics for dry farmland in the province. The simulated results showed that the area-weighted mean soil organic carbon density (SOCD) of dry farmland increased from 18.77 Mg C ha-1 in 1980 to 23.99 Mg C ha-1 in 2008 with an average sequestration rate of 0.18 Mg C ha-1 year-1. Approximately 94.9% of the total dry farmland area sequestered carbon while 5.1% had carbon lost. Over the past 29 years, the net SOC gain in dry farmland soils of the province was 19.37 Tg, with an average sequestration rate of 0.67 Tg C year-1 Augmentation of SOC was primarily due to increased consumption of nitrogen fertilizer and farmyard manure. Moreover,SOC dynamics were highly differentiated among dry farmland soil groups. The integration of the Century model with a fine-scale soil database approach could be conveniently utilized as a tool for the accurate simulation of SOC dynamics at the regional scale.

  6. Heavy metal speciation and risk assessment in dry land and paddy soils near mining areas at Southern China.

    Science.gov (United States)

    Liu, Guannan; Wang, Juan; Zhang, Erxi; Hou, Jing; Liu, Xinhui

    2016-05-01

    Heavy metal contamination of soils has been a long-standing environmental problem in many parts of the world, and poses enormous threats to ecosystem and human health. Speciation of heavy metals in soils is crucial to assessing environmental risks from contaminated soils. In this study, total concentrations and speciation of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were measured for agricultural soils near mines along the Diaojiang River in Guangxi Zhuang Autonomy Region, China. The sources of heavy metals in soils also were identified to assess their effect on speciation distribution of soil heavy metals. Furthermore, the speciation distribution of Cd and Zn, main soil heavy metal pollutants, in dry land and paddy soils were compared. Results showed that there were two severely polluted regions near mine area reaching alarming pollution level. As, Cd, Pb, and Zn were more affected by mining activities, showing very strong pollution level in soils. The mean percentage of exchangeable and carbonate fraction was highest and up to 46.8 % for Cd, indicating a high environmental risk. Greater bioavailable fractions of As, Cd, Cu, Mn, Pb, and Zn were found in soils heavily polluted by mining activities, whereas Cr and Ni as geogenic elements in the stable residual fraction. In addition, in the dry land soils, reducible fraction proportion of Cd was higher than that in the paddy soils, whereas exchangeable and carbonate fraction of Cd was lower than that in the paddy soils. Oxidizable fraction of Zn was higher in the paddy soils than that in the dry land soils. The results indicate that the sources of soil heavy metals and land types affect heavy metal speciation in the soil and are significant for environmental risk assessment of soil heavy metal pollutions. PMID:26801928

  7. Complex sources of air-soil-water pollution processes in the Miyun reservoir region

    Institute of Scientific and Technical Information of China (English)

    YANG; Dongzhen; XU; Xiangde; LIU; Xiaoduan; XU; Qing; DING

    2005-01-01

    The comprehensive impact of atmospheric dry deposition and wet deposition and the pollution sources of farmlands, mining areas, and towns along the Baihe River on the water quality of Miyun reservoir is investigated from the angle of the complex sources of air-soil-water pollution processes, in the context of the 1990-2001 precipitation chemical data at Shangdianzi station--a WMO regional background air pollution monitoring station 15 km far from the Miyun reservoir, in conjunction with the atmospheric dry deposition and wet deposition data of the 2002-2003 Beijing City Air Pollution Observation Field Experiment (BECAPEX). Analysis results suggest that the major ions in precipitation in the Miyun reservoir region in this period were SO, NO, NH and Ca2+; wet acid deposition quantity of Miyun reservoir in the summer half year (April to September) was greater than the quantity in the winter half year (October to March), and the annual wet acid deposition in the reservoir exhibited a rising trend with the mean 1038.45 t, the maximum 1766.31 t occurred in 1996, and the minimum 604.02 t in 1994; the long-term averaged pH of atmospheric precipitation in the Miyun reservoir region was 5.20, i.e. weakly acidic, and the interannual variation of pH values displayed a falling trend. pH values of water body at various depths in the Miyun reservoir were all greater than 7.0, but they exhibited vertical and horizontal nonhomogeneity, and at the same region pH decreased vertically with depth; the 2002 and 2003 annual dustfalls in the Miyun reservoir were 13513.08 t and 3577.64 t, respectively, and the spring dustfall was the number one in a year, accounting for the 61.91% and 44.56% of the annual totals of 2002 and 2003, respectively. Because the atmospheric dry deposition and wet depositions contain multiple types heavy metal elements and harmful elements, they to some extent exacerbated the eutrophication, acidification and potential heavy metal pollution of the reservoir water

  8. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    Science.gov (United States)

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-11-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  9. The effect of wheat boiling time, bulgur particle size, drying time and temperature on some physical properties of hot air dried tarkhineh

    Directory of Open Access Journals (Sweden)

    Arash Ghaitaranpour

    2013-04-01

    Full Text Available Tarkineh is one of the traditional products of western part of Iran. This work was carried out to study drying behavior of Tarkineh. The effect of wheat boiling time (0, 1 and 3.5 hours, drying temperature (70, 80 and 90 °C, drying time (from 30 to 900 minutes and bulgur particle size (fine, medium, coarse on drying behavior of Tarkineh were analyzed. Different mathematical models were applied to evaluate the behavior of Tarkineh during hot air drying and color changes of Tarkineh during hot air drying was assumed using image processing. At the beginning of the drying process, the L* decreased rapidly and b* increasing quickly, but both were relatively stable afterward. a* slightly decreased initially but then depending on the type of sample increased or remain constant. When bulgur particle size increases, generally, the amount of L* increase but a* and b* decrease. The results indicated that At 70 °C, the logarithmic model can present better predictions for the moisture transfer than other models for ultra cooked samples but for raw and cooked samples, the two-term model were appropriate. At 80 and 90 °C, the two-term model was the best descriptive for ultra cooked samples but for raw and cooked samples, the Midilli-Kucuk model were appropriate. Mentioned variables had major effect on the drying behavior of Tarkhineh. For increasing the production rate and improving the color of Tarkineh, boiling of wheat for one hour and drying at 80°C is recommended.

  10. The Use of Principle Component Analysis in Type Classification of Air-dry Peat

    International Nuclear Information System (INIS)

    The use of principle component analysis (PCA) in the variant of projection on latent values with discriminant analysis (PLS-DA) in type classification of Siberian region air-dry peat by a set of properties is presented. A statistical analysis in principle component space by PCA of different physico-chemical properties of peat such as component composition, concentration of paramagnetic centers and IR-spectra is presented and shows a developed PLS- DA classification model allows estimating peat type by a set of physico-chemical properties with minimum prediction errors

  11. DEVELOPMENT OF COAL DRY BENEFICIATION WITH AIR-DENSE MEDIUM FLUIDIZED BED IN CHINA

    Institute of Scientific and Technical Information of China (English)

    Qingru Chen; Lubin Wei

    2005-01-01

    In China more than two-thirds of available coal reserves are in arid areas, where, to beneficiate the run-of-mine coal,there is not enough water resource required by conventional processing. Developing efficient dry beneficiation technology is of great significance for efficient coal utilization in China, notably the clean coal technology (CCT). The dry coal beneficiation technology with air-dense medium fluidized bed utilizes air-solid suspension as beneficiating medium whose density is consistent for beneficiation, similar in principle to the wet dense medium beneficiation using liquid-solid suspension as separating medium. The heavy portion in feedstock whose density is higher than the density of the fluidized bed will sink, whereas the lighter portion will float, thus stratifying the feed materials according to their density.In order to obtain efficient dry separation in air-dense medium fluidized bed, stable fluidization with well dispersed micro-bubbles must be achieved to ensure low viscosity and high fluidity. The pure buoyancy of beneficiation materials plays a main role in fluidized bed, and the displaced distribution effect should be restrained. The displaced distribution effects include viscosity displaced distribution effect and movement displaced distribution effect. The former is caused by viscosity of the fluidized bed. It decreases with increasing air flow velocity. Movement displaced distribution effect will be large when air flow rate is too low or too high. If medium particle size distribution and air flow are well controlled, both displaced distribution effects could be controlled effectively. A beneficiation displaced distribution model may be used to optimize beneficiation of feedstock with a wide particle size distribution and multiple components in the fluidized bed. The rheological characteristics of fluidized beds were studied using the falling sphere method. Experimental results indicated that the fluidized bed behaves as a Bingham fluid

  12. Comparative study of denaturation of whey protein isolate (WPI) in convective air drying and isothermal heat treatment processes.

    Science.gov (United States)

    Haque, M Amdadul; Aldred, Peter; Chen, Jie; Barrow, Colin J; Adhikari, Benu

    2013-11-15

    The extent and nature of denaturation of whey protein isolate (WPI) in convective air drying environments was measured and analysed using single droplet drying. A custom-built, single droplet drying instrument was used for this purpose. Single droplets having 5±0.1μl volume (initial droplet diameter 1.5±0.1mm) containing 10% (w/v) WPI were dried at air temperatures of 45, 65 and 80°C for 600s at constant air velocity of 0.5m/s. The extent and nature of denaturation of WPI in isothermal heat treatment processes was measured at 65 and 80°C for 600s and compared with those obtained from convective air drying. The extent of denaturation of WPI in a high hydrostatic pressure environment (600MPa for 600s) was also determined. The results showed that at the end of 600s of convective drying at 65°C the denaturation of WPI was 68.3%, while it was only 10.8% during isothermal heat treatment at the same medium temperature. When the medium temperature was maintained at 80°C, the denaturation loss of WPI was 90.0% and 68.7% during isothermal heat treatment and convective drying, respectively. The bovine serum albumin (BSA) fraction of WPI was found to be more stable in the convective drying conditions than β-lactoglobulin and α-lactalbumin, especially at longer drying times. The extent of denaturation of WPI in convective air drying (65 and 80°C) and isotheral heat treatment (80°C) for 600s was found to be higher than its denaturation in a high hydrostatic pressure environment at ambient temperature (600MPa for 600s). PMID:23790837

  13. The importance of soil drying and re-wetting in crop phytohormonal and nutritional responses to deficit irrigation.

    Science.gov (United States)

    Dodd, Ian C; Puértolas, Jaime; Huber, Katrin; Pérez-Pérez, Juan Gabriel; Wright, Hannah R; Blackwell, Martin S A

    2015-04-01

    Soil drying and re-wetting (DRW) occurs at varying frequencies and intensities during crop production, and is deliberately used in water-saving irrigation techniques that aim to enhance crop water use efficiency. Soil drying not only limits root water uptake which can (but not always) perturb shoot water status, but also alters root synthesis of phytohormones and their transport to shoots to regulate leaf growth and gas exchange. Re-wetting the soil rapidly restores leaf water potential and leaf growth (minutes to hours), but gas exchange recovers more slowly (hours to days), probably mediated by sustained changes in root to shoot phytohormonal signalling. Partial rootzone drying (PRD) deliberately irrigates only part of the rootzone, while the remainder is allowed to dry. Alternating these wet and dry zones (thus re-wetting dry soil) substantially improves crop yields compared with maintaining fixed wet and dry zones or conventional deficit irrigation, and modifies phytohormonal (especially abscisic acid) signalling. Alternate wetting and drying (AWD) of rice can also improve yield compared with paddy culture, and is correlated with altered phytohormonal (including cytokinin) signalling. Both PRD and AWD can improve crop nutrition, and re-wetting dry soil provokes both physical and biological changes which affect soil nutrient availability. Whether this alters crop nutrient uptake depends on competition between plant and microbes for nutrients, with the rate of re-wetting determining microbial dynamics. Nevertheless, studies that examine the effects of soil DRW on both crop nutritional and phytohormonal responses are relatively rare; thus, determining the cause(s) of enhanced crop yields under AWD and PRD remains challenging. PMID:25628330

  14. Numerical-analytical investigation into impact pipe driving in soil with dry friction. Part I: Nondeformable external medium

    CERN Document Server

    Aleksandrova, Nadezhda

    2013-01-01

    The study focuses on propagation of longitudinal waves in an elastic pipe partly embedded in a medium with dry friction. Mathematical formulation of the problem on the impact pipe driving into the soil is based on the model of longitudinal vibration of an elastic rod with taking into account lateral resistance. The lateral resistance of soil is described by the law of the contact dry friction. Numerical and analytical solutions to problems on longitudinal impulse loading of a pipe are compared.

  15. Predicting Soil-Air and Soil-Water Transport Properties During Soil Vapor Extraction

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe

    Increased application of in-situ technology for control and removal of volatile organic compounds (VOC) in the subsurface has made the understanding of soil physical properties and their impact upon contaminant transport even more important. Knowledge of contaminant transport is important when...... designing and operating remediation systems. Simple and accurate models for estimating soil properties from soil parameters that are easy to measure are useful in connection with preliminary remedial investigations and evaluation of remedial technologies. In this work simple models for predicting transport...... properties of undisturbed soil from more easily measurable soil properties are developed. The importance of soil properties with respect to contaminant migration during remediation by soil vapor extraction (SVE) in the unsaturated zone was investigated using numerical simulations....

  16. Impacts of air, water and soil contamination on forests

    International Nuclear Information System (INIS)

    The result of our literature search is presented; it deals with the measuring points and screens used in the former GDR to determine the stress of the forests by air pollution (immissions, depositions, soil contamination, stress of waters, biological monitoring). In the second part we present the results of our search regarding the research done in the former GDR on methods of forest damage survey, on material balance of forest ecosystems, on modifications in the forest soile caused by depositions, on the possible impacts on the quality of waters, and on the influence of liming and fertilizer application on the material balance of forest stands damaged by immissions. Proposals are made for further research. (orig.)

  17. Effect of incubation temperature and wet-dry cycle on the availabilities of Cd, Pb and Zn in soil

    Institute of Scientific and Technical Information of China (English)

    SI Ji-tao; TIAN Bao-guo; WANG Hong-tao

    2006-01-01

    The effect of incubation temperature and wet-dry cycle on the availabilities of Cd, Pb and Zn was studied. Three soils with pH ranging from 3.8 to 7.3, organic carbon (OC) from 0.7% to 2.4%, and clay from 12.3% to 35.6% were selected. Soils were spiked with reagent grade Cd(NO3)2, Pb(NO3)2, and Zn(NO3)2 at concentrations of 30 mg Cd/kg soil, 300 mg Zn/kg soil and 2000 mg Pb/kg soil. The soils were incubated at 35, 60, 105℃, respectively and went through four wet-dry cycles. Metal availability in soils was estimated by soil extraction with 0.1 mol/L Ca(NO3)2. According to this study, the effect of the spiking temperature on the metal availabilities was different among the metals, soils and wet-dry cycles. Mostly, 35℃ was the first recommended spiking temperature for Cd and Pb while no spiking temperature was obviously better than others for Zn. Three wet-dry cycles was recommended regardless of the type of metals and incubation temperature.

  18. Study of the morphology of corrosion features of natural graphite oxidised by dry and humid air

    International Nuclear Information System (INIS)

    The author reports a study which aimed at highlighting the morphology differences between corrosion features which affect flakes of natural graphite oxidised by dry air and by humid air. The study is based on observations made by optical and transmission electronic microscopy, this last one being performed on replicates. As the so-called 'Hennig' replicates did not result in a sufficient resolution of corrosion feature details, another method has been developed. Three classes of samples (in relationship with the rate of impurities present in samples) have been studied. Flakes have thus been sorted and each flake has then been oxidised at different wear rates. This highlights the influence of damages created by impurities in the lattice

  19. Dry Flowing Abrasive Decontamination Technique for Pipe Systems with Swirling Air Flow

    International Nuclear Information System (INIS)

    A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling air flow containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in air and an exponent of flow rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to 60Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor

  20. Occurrence and quantitative microbial risk assessment of Cryptosporidium and Giardia in soil and air samples

    Directory of Open Access Journals (Sweden)

    Ana Paola Balderrama-Carmona

    2014-09-01

    Conclusions: Soil and air inhalation and/or ingestion are important vehicles for these parasites. To our knowledge, the results obtained in the present study represent the first QMRAs for cryptosporidiosis and giardiasis due to soil and air inhalation/ingestion in Mexico. In addition, this is the first evidence of the microbial air quality around these parasites in rural zones.

  1. Nitrate Accumulation in Soil Profile of Dry Land Farming in Northwest China

    Institute of Scientific and Technical Information of China (English)

    FAN Jun; HAO Ming-De; SHAO Ming-An

    2003-01-01

    A long-term fertilizer experiment on dry land of the Loess Plateau, northwest China, has been conducted since 1984 to study the distribution and accumulation of NO3-N down to a depth of 400 cm in the profile of a coarse-textured dark loessial soil after continuous winter wheat cropping. Thirteen fertilizer treatments consisted of four levels of N and P applied alone or in combination. Annual N and P (P2O5) rates were 0,45, 90, 135 and 180 kg ha-1. After 15 successive cropping cycles, the soil samples were taken from each treatment for analysis of NO3-N concentration. The results showed that NO3-N distribution in the soil profile was quite different among the treatments. The application of fertilizer N alone resulted in higher NO3-N concentration in the soil profile than the combined application of N and P, showing that application of P could greatly reduce the NO3-N accumulation. With an annual application of 180 kg N ha-1 alone, a peak in NO3-N accumulation occurred at 140 cm soil depth, and the maximum NO3-N concentration in the soils was 67.92 mg kg-1. The amount of NO3-N accumulated in the soil profile decreased as the cumulative N uptake by the winter wheat increased. Application of a large amount of N resulted in lower N recoveries in winter wheat and greater NO3-N accumulation in soil profile. NO3-N did not enter underground water in the study region; therefore, there is no danger of underground water pollution. Amount of NO3-N accumulation can be predicted by an equation according to annual N and P rates based on the results of this experiment.

  2. Episodic soil succession on basaltic lava fields in a cool, dry environment

    Science.gov (United States)

    Vaughan, K.L.; McDaniel, P.A.; Phillips, W.M.

    2011-01-01

    Holocene- to late Pleistocene-aged lava flows at Craters of the Moon National Monument and Preserve provide an ideal setting to examine the early stages of soil formation under cool, dry conditions. Transects were used to characterize the amount and nature of soil cover on across basaltic lava flows ranging in age from 2.1 to 18.4 ka. Results indicate that on flows <13 ka, very shallow organic soils (Folists in Soil Taxonomy) are the dominant soil type, providing an areal coverage of up to ∼25%. On flows ≥13.9 ka, deeper mineral soils including Entisols, Aridisols, and Mollisols become dominant and the areal extent increases to ≥95% on flows older than 18.4 ka. These data suggest there are two distinct pedogenic pathways associated with lava flows of the region. The first pathway is illustrated by the younger flows, where Folists dominate. In the absence of a major source of loess, relatively little mineral material accumulates and soils provide only minor coverage of the lava flows. Our results indicate that this pathway of soil development has not changed appreciably over the past ∼10 ka. The second pedogenic pathway is illustrated by the flows older than 13.9 ka. These flows have been subject to deposition of large quantities of loess during and after the last regional glaciation, resulting in almost complete coverage. Subsequent pedogenesis has given rise to Aridisols and Mollisols with calcic and cambic horizons and mollic epipedons. This research highlights the importance of regional climate change on the evolution of Craters of the Moon soilscapes.

  3. Linear GPR inversion for lossy soil and a planar air-soil interface

    DEFF Research Database (Denmark)

    Meincke, Peter

    2001-01-01

    A three-dimensional inversion scheme for fixed-offset ground penetrating radar (GPR) is derived that takes into account the loss in the soil and the planar air-soil interface. The forward model of this inversion scheme is based upon the first Born approximation and the dyadic Green function for a...... two-layer medium. The forward model is inverted using the Tikhonov-regularized pseudo-inverse operator. This involves two steps: filtering and backpropagation. The filtering is carried out by numerically solving Fredholm integral equations of the first kind and the backpropagation is performed using...

  4. Mines buried in dry and saturated soils : blast experiments, soil modeling and simulations

    OpenAIRE

    Roger, Eve

    2015-01-01

    In recent conflicts, vehicles have been facing underbelly attacks involving a large quantity of buried explosive. A part of the energy is absorbed by the deformation of the belly. Still the vehicle is subjected to the impulse transmitted by the detonation which may severely injure occupants. The intensity of the impulse is highly dependent on three main parameters which are the degree of saturation of the soil, the nature of the soil in which the explosive is buried and the depth of burial of...

  5. Field controlled experiments of mercury accumulation in crops from air and soil

    Energy Technology Data Exchange (ETDEWEB)

    Niu Zhenchuan [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Zhang Xiaoshan, E-mail: zhangxsh@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Wang Zhangwei, E-mail: wangzhw@rcees.ac.cn [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China); Ci Zhijia [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085 (China)

    2011-10-15

    Field open top chambers (OTCs) and soil mercury (Hg) enriched experiments were employed to study the influence of Hg concentrations in air and soil on the Hg accumulation in the organs of maize (Zea mays L.) and wheat (Triticum aestivum L.). Results showed that Hg concentrations in foliages were correlated significantly (p < 0.05) with air Hg concentrations but insignificantly correlated with soil Hg concentrations, indicating that Hg in crop foliages was mainly from air. Hg concentrations in roots were generally correlated with soil Hg concentrations (p < 0.05) but insignificantly correlated with air Hg concentrations, indicating that Hg in crop roots was mainly from soil. No significant correlations were found between Hg concentrations in stems and those in air and soil. However, Hg concentrations in upper stems were usually higher than those in bottom stems, implying air Hg might have stronger influence than soil Hg on stem Hg accumulation. - Highlights: > Hg accumulation in crop organs was studied by OTCs and soil Hg enriched experiments. > Hg accumulation in foliages and roots was mainly from air and soil, respectively. > Air Hg had stronger influence than soil Hg on stem Hg accumulation. > Foliar Hg concentrations showed the trend of increase over growth stages. - Capsule Mercury accumulated in the aboveground organs of crop was mainly from the air.

  6. Depth of soil water uptake by tropical rainforest trees during dry periods: does tree dimension matter?

    Science.gov (United States)

    Stahl, Clément; Hérault, Bruno; Rossi, Vivien; Burban, Benoit; Bréchet, Claude; Bonal, Damien

    2013-12-01

    Though the root biomass of tropical rainforest trees is concentrated in the upper soil layers, soil water uptake by deep roots has been shown to contribute to tree transpiration. A precise evaluation of the relationship between tree dimensions and depth of water uptake would be useful in tree-based modelling approaches designed to anticipate the response of tropical rainforest ecosystems to future changes in environmental conditions. We used an innovative dual-isotope labelling approach (deuterium in surface soil and oxygen at 120-cm depth) coupled with a modelling approach to investigate the role of tree dimensions in soil water uptake in a tropical rainforest exposed to seasonal drought. We studied 65 trees of varying diameter and height and with a wide range of predawn leaf water potential (Ψpd) values. We confirmed that about half of the studied trees relied on soil water below 100-cm depth during dry periods. Ψpd was negatively correlated with depth of water extraction and can be taken as a rough proxy of this depth. Some trees showed considerable plasticity in their depth of water uptake, exhibiting an efficient adaptive strategy for water and nutrient resource acquisition. We did not find a strong relationship between tree dimensions and depth of water uptake. While tall trees preferentially extract water from layers below 100-cm depth, shorter trees show broad variations in mean depth of water uptake. This precludes the use of tree dimensions to parameterize functional models. PMID:23852028

  7. Effect of alternate wetting and drying versus continuous flooding on carbon rates in rice and soil

    Directory of Open Access Journals (Sweden)

    M.B. Hossain

    2016-08-01

    Full Text Available An experiment was conducted at Bangladesh Institute of Nuclear Agriculture (BINA farm, Mymensingh, Bangladesh during 2010-2011 to find out the effect of different water and organic residue rates on rice and soil. Organic carbon rates from cow dung (0.5, 1.0, 1.5 and 2.0 t C ha-1 including control were evaluated under alternate wetting and drying (AWD and continuous flooding (CF. CF system in combination with chemical fertilizers and 2.0 t C ha-1 produced the maximum plant height, filled grains tiller-1, 1000 grains weight, grain and straw yields. Combined use of 2.0 t C ha-1 cow dung and CF system decreased CO2-C gas emission, increased carbon accumulation in above ground biomass of rice as well as carbon sequestration in soil. This treatment also helped to optimize soil pH. Based on these results, it may be concluded that continuous flooding system in combination 2.0 t C ha-1 increased grain yield, carbon accumulation in above ground biomass, carbon sequestration in soil and optimized soil pH.

  8. Dried gamma-irradiated sewage solids use on calcareous soils: crop yields and heavy metals uptake

    International Nuclear Information System (INIS)

    The fertilizer values of gamma-irradiated digested sewage solids (RDSS) and gamma-irradiated undigested sewage solids (RUSS) have been examined on calcareous soils. Previously published data from Sandia Laboratories have shown that approximately 1 mega-rad of gamma-irradiation effectively destroys pathogenic bacteria, parasites and plant seeds in dried sewage solids. Greenhouse experiments directly comparing gamma-irradiated and non-irradiated undigested and digested dried sewage solids as fertilizers indicate little or no effect of 1 mega-rad gamma radiation treatment on plant yield or plant-nutrient uptake and demonstrated considerable benefit from using sewage solids on calcareous soils. Plant response to undigested sewage solids was considerably greater than to digested sewage solids when applied at levels that were isonitrogenous. The calcareous soils in New Mexico typically range in pH from 7.5 to 9.0, limiting the plant-availability of many elements, especially heavy metals. Soils irrigated with sewage-effluent for 40 years demonstrated beneficial use of supplied plant-nutrients with no apparent increase in plant-uptake of heavy metals. RDSS applied to a calcareous soil low in plant-available iron increased plant growth in the greenhouse considerably more than treatments with equal amounts of nitrogen, phosphorus and iron applied as common fertilizer materials. Plant tissue concentrations of Fe, Zn, Mn and Cu showed that RDSS was a good source of these nutrients. Results also indicated that the total soluble salt concentration of the RDSS was the factor most limiting plant growth. Chromium, Cd, Ni and Pd plant-tissue concentrations were apparently not increased by RDSS treatments. (Auth.)

  9. Forest structure, diversity and soil properties in a dry tropical forest in Rajasthan, Western India

    Directory of Open Access Journals (Sweden)

    J. I. Nirmal Kumar

    2011-06-01

    Full Text Available Structure, species composition, and soil properties of a dry tropical forest in Rajasthan Western India, were examined by establishment of 25 plots. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 995 stems ha-1 (= 3.0 cm DBH; 52% of those stems were smaller than 10 cm DBH. The total basal area was 46.35 m2ha-1, of which Tectona grandis L. contributed 48%. The forest showed high species diversity of trees. 50 tree species (= 3.0 cm DBH from 29 families were identified in the 25 sampling plots. T. grandis (20.81% and Butea monosperma (9% were the dominant and subdominant species in terms of importance value. The mean tree species diversity indices for the plots were 1.08 for Shannon diversity index (H´, 0.71 for equitability index (J´ and 5.57 for species richness index (S´, all of which strongly declined with the increase of importance value of the dominant, T. grandis. Measures of soil nutrients indicated low fertility, extreme heterogeneity. Regression analysis showed that stem density and the dominant tree height were significantly correlated with soil pH. There was a significant positive relationship between species diversity index and soil available P, exchangeable K+, Ca2+ (all p values < 0.001 and a negative relationship with N, C, C:N and C:P ratio. The results suggest that soil properties are major factors influencing forest composition and structure within the dry tropical forest in Rajasthan.

  10. Chemical-Specific Representation of Air-Soil Exchange and Soil Penetration in Regional Multimedia Models

    Energy Technology Data Exchange (ETDEWEB)

    McKone, T.E.; Bennett, D.H.

    2002-08-01

    In multimedia mass-balance models, the soil compartment is an important sink as well as a conduit for transfers to vegetation and shallow groundwater. Here a novel approach for constructing soil transport algorithms for multimedia fate models is developed and evaluated. The resulting algorithms account for diffusion in gas and liquid components; advection in gas, liquid, or solid phases; and multiple transformation processes. They also provide an explicit quantification of the characteristic soil penetration depth. We construct a compartment model using three and four soil layers to replicate with high reliability the flux and mass distribution obtained from the exact analytical solution describing the transient dispersion, advection, and transformation of chemicals in soil with fixed properties and boundary conditions. Unlike the analytical solution, which requires fixed boundary conditions, the soil compartment algorithms can be dynamically linked to other compartments (air, vegetation, ground water, surface water) in multimedia fate models. We demonstrate and evaluate the performance of the algorithms in a model with applications to benzene, benzo(a)pyrene, MTBE, TCDD, and tritium.

  11. Mathematical Modeling of Drying Kinetics of Bird’s Eye Chilies in a Convective Hot-Air Dryer

    Directory of Open Access Journals (Sweden)

    Kongdej LIMPAIBOON

    2013-12-01

    Full Text Available The drying kinetics of red bird’s eye chilies and the color of the product were investigated in a laboratory scale hot-air dryer under 3 air temperatures of 55, 60 and 65 °C. The 6 mathematical models (Lewis model; Page model; Henderson and Pabis model; Logarithmic model; Modified Page model; and Wang and Singh model were used to fit the experimental data obtained in order to estimate the moisture ratio as the function of drying time. The results showed that operating temperature enhanced the kinetics of the drying of chilies; the drying times of chilies at 55, 60 and 65 °C were 510, 360 and 330 min, respectively. The experimental drying curves obtained at all operating conditions took place in the falling rate period. Comparing the dried products, it was observed that the red bird’s eye chilies dried at a lower temperature had higher Hunter L (lightness, a* (redness and b* (yellowness values. The experimental data were fitted to different drying models. The performance of these models was investigated by comparing the determination of coefficient (R2 and root mean square error (RMSE between the observed and predicted moisture ratios. Among the 6 mathematical models, the Wang and Singh model satisfactorily described the drying kinetics of chilies.

  12. Influence of Dry Soil on the Ability of Formosan Subterranean Termites (Coptotermes formosanus) to Locate Food Sources

    Science.gov (United States)

    The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki, to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three-chambered apparatus were compared for treatments where the soil in the center contai...

  13. Influence of dry soil on the ability of Formosan Subterranean Termites, Coptotermes formosanus, to locate food sources.

    Science.gov (United States)

    The effect of barriers of dry soil on the ability of Formosan subterranean termites, Coptotermes formosanus Shiraki, to construct tunnels and find food was evaluated. Termite movement and wood consumption in a three-chambered apparatus were compared for treatments where the soil in the center contai...

  14. Microbial diversity of a Mediterranean soil and its changes after biotransformed dry olive residue amendment.

    Directory of Open Access Journals (Sweden)

    José A Siles

    Full Text Available The Mediterranean basin has been identified as a biodiversity hotspot, about whose soil microbial diversity little is known. Intensive land use and aggressive management practices are degrading the soil, with a consequent loss of fertility. The use of organic amendments such as dry olive residue (DOR, a waste produced by a two-phase olive-oil extraction system, has been proposed as an effective way to improve soil properties. However, before its application to soil, DOR needs a pre-treatment, such as by a ligninolytic fungal transformation, e.g. Coriolopsis floccosa. The present study aimed to describe the bacterial and fungal diversity in a Mediterranean soil and to assess the impact of raw DOR (DOR and C. floccosa-transformed DOR (CORDOR on function and phylogeny of soil microbial communities after 0, 30 and 60 days. Pyrosequencing of the 16S rRNA gene demonstrated that bacterial diversity was dominated by the phyla Proteobacteria, Acidobacteria, and Actinobacteria, while 28S-rRNA gene data revealed that Ascomycota and Basidiomycota accounted for the majority of phyla in the fungal community. A Biolog EcoPlate experiment showed that DOR and CORDOR amendments decreased functional diversity and altered microbial functional structures. These changes in soil functionality occurred in parallel with those in phylogenetic bacterial and fungal community structures. Some bacterial and fungal groups increased while others decreased depending on the relative abundance of beneficial and toxic substances incorporated with each amendment. In general, DOR was observed to be more disruptive than CORDOR.

  15. Effect mechanism of air deflectors on the cooling performance of dry cooling tower with vertical delta radiators under crosswind

    International Nuclear Information System (INIS)

    Highlights: • A 3D numerical model was set for NDDCTV to study the effect of air deflectors. • The air deflectors improve the tower performance by 1.375 °C at uc = 6 m/s for a case. • The air deflectors reduce the air inflow deviation angle θd at most delta entries. • The reduced θd can improve the cooling performance of former deteriorated columns. • Both the radial inflow air velocity and θd impact the cooling performance of delta. - Abstract: To study the effect mechanism of air deflectors on dry cooling tower, a three dimensional numerical model was established, with full consideration of the delta structure. The accuracy and credibility of dry cooling tower numerical model were validated. By numerical model, the average air static pressure and the average radial inflow air velocity were computed and analyzed at delta air entry, sector air entry and exit faces. By the air inflow deviation angle θd, the effect of air deflectors on the aerodynamic field around tower was analyzed. The water exit temperatures of θ−1 columns, θ+2 columns and cooling sectors were also presented to clarify the effect of air deflectors. It was found that the air deflectors improved the aerodynamic field around cooling columns. The reduced air inflow deviation degree at delta entry improved the cooling performance of deteriorated columns. Referring to the radial inflow air velocity ura and the air inflow deviation degree at delta entry, the effect mechanism of air deflectors are clarified under crosswind

  16. Analysis of Phthalate Esters in Air, Soil and Plants in Plastic Film Greenhouse

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The phthalate esters such as DMP, DEP, DBP and DEHP in air, soil and plant samples in plastic film greenhouse were clean up with fine silica gel column and determined with HPLC. It was found that the concentrations of PEs in air and soil samples in plastic film greenhouse are much higher than those of contrast samples. But concentrations of PEs in plants in plastic film greenhouse are not remarkably affected by the pollution of air and soil.

  17. Solar Park Impacts on Air and Soil Microclimate

    Science.gov (United States)

    Armstrong, A.; Ostle, N. J.; Whitaker, J.

    2015-12-01

    The drive towards low carbon energy sources and increasing energy demand has resulted in a rapid rise in solar photovoltaics across the world. A substantial proportion of photovoltaics are large-scale ground-mounted systems, solar parks, causing a notable land use change. While the impacts of photovoltaic panel production and disposal have been considered, the consequences of the operation of solar parks on the hosting landscape are poorly resolved. Here, we present data which demonstrates that a solar park sited on permanent grassland in the UK significantly impacted the air and soil microclimate. Specifically, we observed (1) cooler soil under the photovoltaic panels during the summer and between the photovoltaic panel rows during the winter; (2) dampening of the diurnal variation in air temperature and absolute humidity from the spring to the autumn; (3) lower photosynthetically active radiation and a lower direct:diffuse under the panels; and (4) reduced wind speed between the panel rows and substantially reduced wind speeds under the panels. Further, there were differences in vegetation type and productivity and greenhouse gas emissions. Given the centrality of climate on ecosystem function, quantifying the microclimatic impacts of this emerging land use change is critical. We anticipate these data will help develop understanding of effects in other climates, under different solar park designs and the implications for the function and service provision of the hosting landscape.

  18. Environmental application of nanotechnology: air, soil, and water.

    Science.gov (United States)

    Ibrahim, Rusul Khaleel; Hayyan, Maan; AlSaadi, Mohammed Abdulhakim; Hayyan, Adeeb; Ibrahim, Shaliza

    2016-07-01

    Global deterioration of water, soil, and atmosphere by the release of toxic chemicals from the ongoing anthropogenic activities is becoming a serious problem throughout the world. This poses numerous issues relevant to ecosystem and human health that intensify the application challenges of conventional treatment technologies. Therefore, this review sheds the light on the recent progresses in nanotechnology and its vital role to encompass the imperative demand to monitor and treat the emerging hazardous wastes with lower cost, less energy, as well as higher efficiency. Essentially, the key aspects of this account are to briefly outline the advantages of nanotechnology over conventional treatment technologies and to relevantly highlight the treatment applications of some nanomaterials (e.g., carbon-based nanoparticles, antibacterial nanoparticles, and metal oxide nanoparticles) in the following environments: (1) air (treatment of greenhouse gases, volatile organic compounds, and bioaerosols via adsorption, photocatalytic degradation, thermal decomposition, and air filtration processes), (2) soil (application of nanomaterials as amendment agents for phytoremediation processes and utilization of stabilizers to enhance their performance), and (3) water (removal of organic pollutants, heavy metals, pathogens through adsorption, membrane processes, photocatalysis, and disinfection processes). PMID:27074929

  19. Forest structure, diversity and soil properties in a dry tropical forest in Rajasthan, Western India

    OpenAIRE

    J. I. Nirmal Kumar,; Kanti Patel,; Rohit Bhoi Kumar

    2011-01-01

    Structure, species composition, and soil properties of a dry tropical forest in Rajasthan Western India, were examined by establishment of 25 plots. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 995 stems ha-1 (≥ 3.0 cm DBH); 52% of those stems were smaller than 10 cm DBH. The total basal area was 46.35 m2ha-1, of which Tectona grandis L. contributed 48%. The fo...

  20. Forest structure, diversity and soil properties in a dry tropical forest in Rajasthan, Western India

    OpenAIRE

    Nirmal Kumar, J.I.; Kanti Patel,; Kumar, Rita N.; Rohit Bhoi Kumar

    2011-01-01

    Structure, species composition, and soil properties of a dry tropical forest in Rajasthan Western India, were examined by establishment of 25 plots. The forest was characterized by a relatively low canopy and a large number of small-diameter trees. Mean canopy height for this forest was 10 m and stands contained an average of 995 stems ha-1 (= 3.0 cm DBH); 52% of those stems were smaller than 10 cm DBH. The total basal area was 46.35 m2ha-1, of which Tectona grandis L. contributed 48%. The fo...

  1. Resource Limitations on Soil Microbial Activity in an Antarctic Dry Valley

    DEFF Research Database (Denmark)

    Sparrow, Asley; Gregorich, Ed; Hopkins, David; Novis, P; Elberling, Bo; Greenfield, L.G.

    2011-01-01

    Although Antarctic dry valley soils function under some of the harshest environmental conditions on the planet, there is significant biological activity concentrated in small areas in the landscape. These productive areas serve as a source of C and N in organic matter redistributed to the......, when that constraint is alleviated, the organisms are able to access a pool of stored C that they could not metabolize before. The effects of added C and N substrates on respiration rates under laboratory conditions were more rapid and significant than the response rates measured in situ. Because the...

  2. Thermal comfort in air-conditioned mosques in the dry desert climate

    Energy Technology Data Exchange (ETDEWEB)

    Al-ajmi, Farraj F. [Department of Civil Engineering, College of Technological Studies, Shuwaikh 70654 (Kuwait)

    2010-11-15

    In Kuwait, as in most countries with a typical dry desert climate, the summer season is long with a mean daily maximum temperature of 45 C. Centralized air-conditioning, which is generally deployed from the beginning of April to the end of October, can have tremendous impact on the amount of electrical energy utilized to mechanically control the internal environment in mosque buildings. The indoor air temperature settings for all types of air-conditioned buildings and mosque buildings in particular, are often calculated based on the analytical model of ASHRAE 55-2004 and ISO 7730. However, a field study was conducted in six air-conditioned mosque buildings during the summers of 2007 to investigate indoor climate and prayers thermal comfort in state of Kuwait. The paper presents statistical data about the indoor environmental conditions in Kuwait mosque buildings, together with an analysis of prayer thermal comfort sensations for a total of 140 subjects providing 140 sets of physical measurements and subjective questionnaires were used to collect data. Results show that the neutral temperature (T{sub n}) of the prayers is found to be 26.1 C, while that for PMV is 23.3 C. Discrepancy of these values is in fact about 2.8 C higher than those predicted by PMV model. Therefore, thermal comfort temperature in Kuwait cannot directly correlate with ISO 7730 and ASHRAE 55-2004 standards. Findings from this study should be considered when designing air conditioning for mosque buildings. This knowledge can contribute towards the development of future energy-related design codes for Kuwait. (author)

  3. Impact of warming and drying on microbial activity in subarctic tundra soils: inferences from patterns in extracellular enzyme activity

    Science.gov (United States)

    Schade, J. D.; Natali, S.; Spawn, S.; Sistla, S.; Schuur, E. A. G.

    2014-12-01

    Permafrost contains a large pool of carbon that has accumulated for thousands of years, and remains frozen in organic form. As climate warms, permafrost thaw will increase rates of microbial breakdown of old soil organic matter (SOM), accelerating release of carbon to the atmosphere. Higher rates of microbial decomposition may also release reactive nitrogen, which may increase plant production and carbon fixation. The net effect on atmospheric carbon, and the strength of climate feedback, depends on the balance between direct and indirect effects of increased microbial activity, which depends on changes in soil conditions and microbial responses to them. In particular, soil moisture and availability of C and N for microbes strongly influence soil respiration and primary production. Current understanding of changes in these factors as climate warms is limited. We present results from analysis of soil extracellular enzyme activities (EEA) from a long-term warming and drying experiment in subarctic Alaskan tundra (the CiPEHR experiment) as an indicator of changes in soil microbial activity and relative availability of C and N for microbes. We collected soil samples from control (C), warming (W), and warming + drying (WD) treatments and used fluorometric methods to estimate EEA in shallow (0-5 cm) and deep (5-15) soils. We measured soil moisture, SOM, and C:N, and plant tissue C:N as an indicator of N availability. Activity of N-acquiring enzymes was higher in WD soils at both depths. Carbon EEA in W soils was lower in surface, but higher in deeper soils. We also found significantly lower soil C:N in both W and WD in deeper soils, where C:N was generally lower than surface. In general, EEA results suggest drying leads to increased C availability relative to N. This may be due to lower soil moisture leading to greater aeration of soils in WD plots relative to W plots, which may be saturated due to significant land subsidence. Greater aeration may increase efficiency of

  4. Biochar effects on wet and dry regions of the soil water retention curve of a sandy loam

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Moldrup, Per; Sun, Zhencai;

    2014-01-01

    Reported beneficial effects of biochar on soil physical properties and processes include decreased soil density, and increased soil water transport, water holding capacity and retention (mainly for the wet region). Research is limited on biochar effects on the full soil water retention curve (wet...... and dry regions) for a given soil and biochar amendment scenarios. This study evaluates how biochar applied to a sandy loam field at rates from 0 to 50 Mg ha−1 yr–1 in 2011, 2012, or both years (2011+2012) influences the full water retention curve. Inorganic fertilizer and pig slurry were added to all...... treatments. Six months after the last biochar application, intact and disturbed soil samples were collected for analyses. Soil water retention was measured from −1 kPa to −100 kPa using tension tables and ceramic plates and from −10 MPa to −480 MPa using a Vapor Sorption Analyzer. Soil specific area was...

  5. Agrogenic transformation of soils in the dry steppe zone under the impact of antique and recent land management practices

    Science.gov (United States)

    Lisetskii, F. N.

    2008-08-01

    Virgin, cultivated, and old-arable soils have been studied in the area of Olbia, one of the antique poleis in the northern part of the Black Sea region. It is shown that the soils cultivated during the antique time still preserve some features differing them from their virgin analogues. In the course of agrogenic evolution, progressive changes in the morphology of dry steppe soils are not accompanied by the improvement of soil aggregation at lower levels. Macromorphological indices attest to the enhanced development of humification processes and leaching of carbonates and soluble salts in the soils cultivated during the antique time. At the same time, a number of soil degradation processes are vividly manifested in the cultivated soils. It is suggested that this process can be referred to as the soil allopseudomorphosis.

  6. Modeling relationship between runoff and soil properties in dry-farming lands, NW Iran

    Directory of Open Access Journals (Sweden)

    A. R. Vaezi

    2010-04-01

    Full Text Available The process of transformation of rainfall into runoff over a catchment is very complex and exhibits both temporal and spatial variability. However, in a semi-arid area this variability is mainly controlled by the physical and chemical properties of the soil surface. Developing an accurate and easily-used model that can appropriately determine the runoff generation value is of strong demand. In this study a simple, an empirically based model developed to explore effect of soil properties on runoff generation. Thirty six dry-farming lands under follow conditions in a semi-arid agricultural zone in Hashtroud, NW Iran were considered to installation of runoff plots. Runoff volume was measured at down part of standard plots under natural rainfall events from March 2005 to March 2007. Results indicated that soils were mainly clay loam having 36.7% sand, 31.6% silt and 32.0% clay, and calcareous with about 13% lime. During a 2-year period, 41 natural rainfall events produced surface runoff at the plots. Runoff was negatively (R2=0.61, p<0.001 affected by soil permeability. Runoff also significantly correlated with sand, coarse sand, silt, organic matter, lime, and aggregate stability, while its relationship with very fine sand, clay, gravel and potassium was not significant. Regression analysis showed that runoff was considerably (p<0.001, R2=0.64 related to coarse sand, organic matter and lime. Lime like to coarse sand and organic matter positively correlated with soil permeability and consequently decreased runoff. This result revealed that, lime is one of the most important factors controlling runoff in soils of the semi-arid regions.

  7. Effects of Savanna trees on soil nutrient limitation and carbon-sequestration potential in dry season

    Science.gov (United States)

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

    2016-04-01

    limitation and thus in C mineralization and sequestration. The effects on soil respiration are present, even under strong water scarcity. Therefore, the capability of a savanna ecosystem to act as a C sink during dry season is mainly (directly and indirectly) dependent on the spatial abundance of trees.

  8. Effect of Air Relative Humidity Harvest on Soil Moisture Content under Moroccan Climatic Conditions

    Directory of Open Access Journals (Sweden)

    El Khadir Lakhal

    2015-04-01

    Full Text Available In this work, we aim to analyse the effect of the harvest of air relative humidity on soil water content. Some experiments were conducted on hilly areas with various hypsographic and microclimatic conditions greatly affecting daily fluctuations of air relative humidity. The metrological data’s were obtained by using a Campbell Scientific equipments station recorder on data loggers every half hour. Time Domain Reflectometers (TDR is used for calculating water content at different soil layers. The effect of many parameters such as: minimal and maximal air atmospheric humidity, potential of soil water and minimal temperature of air on harvesting air relative humidity is also discussed. The experimental results indicate that soil moisture content in the upper soil layer fluctuates with the same manner to diurnal fluctuation of relative air humidity. These fluctuations due to the harvest of relative air humidity decreased with increasing soil depth and daily amplitude of relative air humidity. The water adsorbed according to this phenomenon increased with increasing maximal relative and decreasing minimal temperature. The contribution of this soil water collected is about 40% of losses due to evaporation process. The correlation between principal climatic data and soil water adsorption by harvest relative air humidity is presented in this paper in order to incorporate it in the total water balance during water infiltration.

  9. Carbon balance of surfaces vs. ecosystems: advantages of measuring eddy covariance and soil respiration simultaneously in dry grassland ecosystems

    Directory of Open Access Journals (Sweden)

    Z. Nagy

    2011-02-01

    Full Text Available An automated open system for measurement of soil CO2 efflux (Rsc was developed and calibrated against known fluxes and tested in the field, while measuring soil respiration also by the gradient method (Rsg at a dry sandy grassland (Bugac, Hungary. Ecosystem respiration (Reco was measured by the eddy covariance technique. Small chamber size (5 cm in diameter of the chamber system made it possible to use the chambers also in vegetation gaps, thereby avoiding the necessity of removing shoots, the disturbance of the spatial structure of vegetation and the upper soil layer. Low air flow rates associated with small chamber volume and chamber design allowed the overpressure range to stabilize between 0.05–0.12 Pa. While the correlation between ecosystem and soil CO2 efflux rates as measured by the independent methods was significant, Reco rates were similar or even lower than Rsc in the low flux (up to 2 μmol CO2 m−2 s−1 range, probably due to the larger than assumed storage flux. The gradient method showed both up and downward CO2 fluxes originating from the main rooting zone after rains. Downward fluxes within the soil profile amounted to 15% of the simultaneous upward fluxes and to ~ 7.6% of the total (upward effluxes during the 3 months study. The upper 5 cm soil layer contributed to ~ 50% of the total soil CO2 efflux. The continuously operated automatic open chamber system and the gradient system makes possible the detection of situations when the eddy system underestimates Reco, gives the lower limit of underestimation (chamber system and helps in quantifying the downward flux component of soil respiration (gradient method between the soil layers. These latter (downward fluxes are expected to seriously affect (1 the Reco vs. temperature

  10. Sporulation and Germination patterns - hedging a bet on long term microbial survivability in dry soil

    Science.gov (United States)

    Claes, N.; Or, D.

    2012-04-01

    Soil hosts unparalleled diversity of microbial life that is constantly challenged by the vagaries of fluctuating ambient conditions. Desiccation stresses play a key role not only by directly affecting individual bacterial cells, but also by shaping diffusion pathways and cell dispersion. The gradual thinning and fragmentation of the aqueous environment during drying have led to different survival mechanisms including dormancy and sporulation, resulting in a highly resistive state capable of surviving extreme and prolonged environmental stresses until conditions improve in the future. Our aim is to investigate how temporal changes in hydration status shape microbial communities over time, based on simple survival strategy rules for each individual bacterium. The two survival strategies considered are dormancy and sporulation. Dormancy is the state in which bacterial cells significantly reduce their metabolism with minor morphological adaptations. The required energy and time for attaining this state are low relative to sporulation costs. Sporulation involves several morphological and biochemical changes that result in a resistive capsule that endures extreme stresses over long periods of time. The working hypothesis is that different micro-ecological conditions and community compositions would result from temporal patterns and magnitude of desiccation stresses. An Individual Based Model (IBM) considering habitats on rough soil surfaces and local effects of micro-hydrological conditions on dispersion and nutrient diffusion would enable systematic study of emerging communities over extended periods. Different population compositions are expected to emerge based on low and high frequency, duration and amplitudes of wetting-drying cycles reflecting relative success or failure of survival strategy.

  11. Change in dry matter and nutritive composition of Brachiaria humidicola grown in Ban Thon soil series

    Directory of Open Access Journals (Sweden)

    Jeerasak Chobtang

    2008-11-01

    Full Text Available This experiment was conducted to determine the change in dry matter and nutritive composition of Humidicola grass (Brachiaria humidicola grown in Ban Thon soil series (infertility soil as a function of growth age. One rai (0.16 ha of two-year-old pasture of fertilised Humidicola grass was uniformly cut and the regrowth samples were collected every twenty days. The samples were subjected to analysis for dry matter content and nutritive composition, i.e. crude protein, ash, calcium, phosphorus, neutral detergent fibre, acid detergent fibre, and acid detergent lignin. The results showed that while the yields of available forage and leaves increased curvilinearly (quadratic, p<0.05, the stem yield increased linearly (p<0.05 over sampling dates. The highest biomass accumulation rate was numerically observed between 40-60 days of regrowth. The concentrations of crude protein, ash, calcium and phosphorus decreased curvilinearly (quadratic, p<0.05 with advancing maturity and reached the lowest flat after 60 days of regrowth. The cell wall components, i.e. NDF, ADF and ADL, increased over the experimental period and reached the highest plateau at 40 days of regrowth. It was concluded that Humidicola grass should be grazed or preserved at the regrowth age of not over 60 days to maximise the utilisation of the grass.

  12. A passive air-cooled dry storage facility for vitrified high-level wastes

    International Nuclear Information System (INIS)

    A conceptual design of air-cooled dry storage vault facility for vitrified high-level waste (HLW) canisters is developed for a site in northern Japan. The facility is designed for the reception and unloading of shielded seagoing transportation casks of vitrified HLW canisters, for the inspection of these canisters, and for their temporary storage for a period of up to 50 years. The waste is to be at least 9 years old when received, and the facility will be capable of storing up to 2,500 canisters. This paper provides a conceptual design to identify construction requirements, materials, and space requirements that are unique to the vitrified HLW storage facility. It also identifies the types of special systems and equipment needed in such a facility

  13. Dust particle charge screening in the dry-air plasma produced by an external ionization source

    International Nuclear Information System (INIS)

    The ionic composition of the plasma produced by an external ionization source in dry air at atmospheric pressure and room temperature and the screening of the electric field of a dust particle in such a plasma have been investigated. The point sink model based on the diffusion-drift approximation has been used to solve the screening problem. We have established that the main species of ions in the plasma under consideration are O4+, O2-, and O4- and that the dust particle potential distribution is described by a superposition of four exponentials with four different constants. We show that the first constant coincides with the inverse Debye length, the second is described by the inverse ambipolar diffusion length of the positive and negative plasma components in the characteristic time of their recombination, the third is determined by the conversion of negative ions, and the fourth is determined by the attachment and recombination of electrons and diatomic ions

  14. Autotrophic component of soil respiration is repressed by drought more than the heterotrophic one in a dry grassland

    Science.gov (United States)

    Balogh, J.; Papp, M.; Pintér, K.; Fóti, Sz.; Posta, K.; Eugster, W.; Nagy, Z.

    2015-10-01

    Summer droughts projected to increase in Central Europe due to climate change strongly influence the carbon cycle of ecosystems. Persistent respiration activities during drought periods are responsible for a significant carbon loss, which may turn the ecosystem from sink to source of carbon. There are still gaps in our knowledge regarding the characteristic changes taking place in the respiration of the different components of the ecosystem respiration in response to drought events. Here, we combined a physical separation of soil respiration components with continuous measurements of soil CO2 efflux and its isotopic (13C) signal at a dry grassland site in Hungary. The physical separation of soil respiration components was achieved by the use of inox meshes and tubes inserted into the soil. The root-excluded and root- and mycorrhiza-excluded treatments served to measure the isotopic signal of the rhizospheric, mycorrhizal fungi and heterotrophic components, respectively. In the dry grassland investigated in this study the three components of the soil CO2 efflux decreased at different rates under drought conditions. During drought the contribution made by the heterotrophic components was the highest. Rhizospheric component was the most sensitive to soil drying with its relative contribution to the total soil respiration dropping from 71 ± 4 % (non-stressed) to 36 ± 12 % under drought conditions. According to our results, the heterotrophic component of soil respiration is the major contributor to the respiration activities during drought events.

  15. Seismic Structure-Soil-Structure Interaction Analysis of a Consolidated Dry Storage Module for CANDU Spent Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Young Gon; Yoon, Jeong Hyoun; Kim, Sung Hwan; Yang, Ke Hyung; Lee, Heung Young; Cho, Chun Hyung [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of); Choi, Kyu Sup; Jeong, In Su [KONES Corporation, Seoul (Korea, Republic of)

    2005-07-01

    The MACSTOR/KN-400 module has been developed as an effective alternative to the existing stand alone concrete canister for dry storage of CANDU spent fuel. The structure is a concrete monolith of 21.67 m long and 12.66 m wide and has a height equal to 7.518 m including the bottom slab. Inside the concrete module consists of 40 storage cylinders accommodating ten 60-bundle dry storage baskets, which are suspended from the top slab and eventually restrained at 10 cm above the bottom slab with horizontal seismic restraints. The main cooling process of the MACSTOR/KN-400 module shall be by air convection through air inlets and outlets. The civil design parameters, with respect to meteorological and seismic loads applied to the module are identical to those specified for the Wolsung CANDU 3 and 4 plants, except for local site characteristics required for soilstructure interaction (SSI) analysis. It is required for the structural integrity to fulfill the licensing requirements. As per USNRC SRP Section 3.7.2, it shall be reviewed how to consider the phenomenon of coupling of the dynamic response of adjacent structures through the soil, which is referred to as structure-soil-structure interaction (SSSI). The presence of closely spaced multiple structural foundations creates coupling between the foundations of individual structures . Some observations of the actual seismic response of structures have indicated that SSSI effects do exist, but they are generally secondary for the overall structural response motions. SSSI effects, however, may be important for a relatively small structure which is to be close to a relatively large structure, while they may be generally neglected for overall structural response of a large massive structure, such as nuclear power plant. As such the scope of the present paper is to carry out a seismic SSSI analysis in case of the MACSTOR/KN- 400 module, in order to investigate whether or not SSSI effect shall be included in the overall seismic

  16. Experimental evaluation of dry/wet air-cooled heat exchangers. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, S.G.; Gruel, R.L.; Huenefeld, J.C.; Eschbach, E.J.; Johnson, B.M.; Kreid, D.K.

    1982-08-01

    The ultimate goal of this project was to contribute to the development of improved cooling facilities for power plants. Specifically, the objective during FY-81 was to experimentally determine the thermal performance and operating characteristics of an air-cooled heat exchanger surface manufactured by the Unifin Company. The performance of the spiral-wound finned tube surface (Unifin) was compared with two inherently different platefin surfaces (one developed by the Trane Co. and the other developed by the HOETERV Institute) which were previously tested as a part of the same continuing program. Under dry operation the heat transfer per unit frontal area per unit inlet temperature difference (ITD) of the Unifin surface was 10% to 20% below that of the other two surfaces at low fan power levels. At high fan power levels, the performances of the Unifin and Trane surfaces were essentially the same, and 25% higher than the HOETERV surface. The design of the Unifin surface caused a significantly larger air-side pressure drop through the heat exchanger both in dry and deluge operation. Generally higher overall heat transfer coefficients were calculated for the Unifin surface under deluged operation. They ranged from 2.0 to 3.5 Btu/hr-ft/sup 2/-/sup 0/F as compared to less than 2.0 Btu hr-ft/sup 2/-/sup 0/F for the Trane and HOETERV surfaces under similar conditions. The heat transfer enhancement due to the evaporative cooling effect was also measureably higher with the Unifin surface as compared to the Trane surface. This can be primarily attributed to the better wetting characteristics of the Unifin surface. If the thermal performance of the surfaces are compared at equal face velocities, the Unifin surface is as much as 35% better. This method of comparison accounts for the wetting characteristics while neglecting the effect of pressure drop. Alternatively the surfaces when compared at equal pressure drop essentially the same thermal performance.

  17. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

    Directory of Open Access Journals (Sweden)

    E. Uusitalo

    2016-01-01

    Full Text Available Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm was measured using specimens that were (1 moist and (2 air-dried (n=5. Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2, and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p<0.05. The increase of the specimen thickness decreased light transmission in all groups (p<0.005, and moist specimens attenuated light less than air-dried specimens in all thicknesses (p<0.05. EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness (p<0.05. Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm. Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert’s law.

  18. Long term high temperature oxidation resistance of a nanoceria coated 316 SS under dry air conditions

    International Nuclear Information System (INIS)

    In this work, nanoceria dip coated and uncoated 316 stainless steels were exposed to dry air at 1073–1273 K for times of up to 250 h. From this work, measured activation energies, Q = 256 kJ mol−1 and Q = 240 kJ mol−1 were found for coated and uncoated 316 SS, respectively. In the coated steel, the activation energy for oxidation cannot be attributed to a single mass transport mechanism. In addition, the scale morphologies, as well as the dominant oxide phases were determined by X-ray diffraction means. It was found that in the nanoceria dip coated steels, the scale was fine grained and highly adherent. Oxidation at increasing temperatures in the coated steels favored the development of the spinel ((Mn, Cr)3O4 structure and at 1273 K with the presence of Fe2O3 was severely hindered. In contrast, in the uncoated steel, a relatively thick scale, predominantly Fe2O3 developed and it exhibited severe damage through spallation and detachment from the steel substrate. Also, the resultant grain structure was rather coarse and it consisted of faceted grains with continuous nucleation/growth at grain ledges. - Highlights: • A 316 SS was dip coated with 3.45 nm nanoceria particles and oxidized in hot dry air. • Activation energies were determined by exposure to 1073–1273 K for up to 250 h. • The coated 316 SS exhibited a reduction in oxidation rates of 1–2 orders of magnitude. • At 1273 K the scale developed in the coated steel was a fine grained spinel MnCr2O4

  19. Quantifying the Resilience of Vegetation and Soil Moisture During Dry Spells Using Satellite Remote Sensing

    Science.gov (United States)

    Stampoulis, D.; Andreadis, K.; Granger, S. L.; Fisher, J. B.; Behrangi, A.; Das, N. N.; Turk, J.

    2014-12-01

    Manifestations of the constantly intensifying hydrological cycle differ substantially among the various regions of the globe. The spatial distribution, magnitude, as well as timing of precipitation events are being altered globally, resulting in significant biotic implications. Motivated by the pressing need to understand how the different components of natural habitats behave under extreme hydrologic conditions, we quantitatively assessed the response of two major hydrological attributes, namely soil moisture (SM) and vegetation water content (VWC) to rainfall deficiencies. More specifically, using multi-year microwave remote sensing observations, we quantified the changes of VWC and SM during dry spells, as well as their resilience during those periods. Differences among vegetation types, as well as the effect of the duration of the dry spells were also investigated. Finally, spatial patterns and characteristics of the response of VWC and SM to sustained precipitation deficits were identified across the study area, and within each of the major vegetation regimes of the region. This hydro-ecological study provides critical insight into the behavior of two crucial components of the natural ecosystems during prolonged dry periods, which in turn yields useful information on the role of the hydrologic regimes in determining biotic composition and patterns, as well as the regional micro-climatology. Furthermore, this information can significantly contribute towards the achievement of more efficient and precise farming practices at the local level, resulting in the increase of food security and societal well-being.

  20. Comparison of CO2 and O2 concentrations in soil air: A lesson learned about CO2 diffusivity in soils

    Science.gov (United States)

    Angert, A.; Davidson, E. A.; Savage, K.; Yakir, D.; Luz, B.

    2002-12-01

    Soil respiration is a major component of the global carbon and oxygen cycles and accounts for about one quarter of global respiration. Since respiration consumes O2 and emits CO2, a simple relationship may be expected between the concentration of these gases in soil-air. However, because the [O2] signal in well-drained soils is small, deriving this relationship from field observations is not trivial. In this study, we present high accuracy measurements of O2 concentrations in soil air, that for the first time, enable precise comparison of these concentrations with CO2 concentrations. Soil air was sampled in two sites: an orchard in Israel, and a temperate forest (Harvard forest). The expected ratio of the decrease in [O2] in soil air to the increase in [CO2] can be calculated from the ratio of O2 consumption to CO2 emission in respiration, and the ratio between the diffusivities of these two gases in air as 0.79-0.07. The measured ratio of the decrease in [O2] to the increase in [CO2] in soil air was 0.56-2.48 in the orchard site and 1.06-1.20 in Harvard Forest. These ratios deviate strongly from the expected relationship. In the orchard site, these deviations were probably caused by reactions in the carbonate system due to the calcareous soil of this site. At Harvard Forest, such reactions cannot be quantitatively important because of the low pH of the soil. In this site, we propose that the relationship between CO2 and O2 in the soil air indicates that the ratio of diffusivity of O2 and CO2 in soils is higher than the diffusivity ratio in air. Our results demonstrate that a combination of high accuracy measurements of the O2 and CO2 in soil air is important for better understanding of the soil CO2 dynamics. Such observations will improve estimates of soil respiration that are based only on CO2 concentration and diffusivity.

  1. A dynamic programming approach to water allocation for seasonally dry area, based on stochastic soil moisture

    Science.gov (United States)

    Lu, Z.; Porporato, A. M.

    2012-12-01

    seasonally dry areas, which are widely distributed in the world, are usually facing an intensive disparity between the lack of natural resource and the great demand of social development. In dry seasons of such areas, the distribution/allocation of water resource is an extremely critical and sensitive issue, and conflicts often occur due to lack of appropriate water allocation scheme. Among the many uses of water, the need of agricultural irrigation water is highly elastic, but this factor has not yet been made full use to free up water from agriculture use. The primary goal of this work is to design an optimal distribution scheme of water resource for dry seasons to maximize benefits from precious water resources, considering the high elasticity of agriculture water demand due to the dynamic of soil moisture affected by the uncertainty of precipitation and other factors like canopy interception. A dynamic programming model will be used to figure out an appropriate allocation of water resources among agricultural irrigation and other purposes like drinking water, industry, and hydropower, etc. In this dynamic programming model, we analytically quantify the dynamic of soil moisture in the agricultural fields by describing the interception with marked Poisson process and describing the rainfall depth with exponential distribution. Then, we figure out a water-saving irrigation scheme, which regulates the timetable and volumes of water in irrigation, in order to minimize irrigation water requirement under the premise of necessary crop yield (as a constraint condition). And then, in turn, we provide a scheme of water resource distribution/allocation among agriculture and other purposes, taking aim at maximizing benefits from precious water resources, or in other words, make best use of limited water resource.

  2. The impacts of drying and rewetting cycles on potential methanogenesis in wetland soils

    Science.gov (United States)

    Kannenberg, S.; Ludwig, S.; Nelson, L.; Rich, H.; Spawn, S.; Porterfield, J.; Schade, J. D.

    2012-12-01

    Wetlands are currently the world's largest natural emitter of methane, a greenhouse gas that is over 20 times more effective at trapping heat than carbon dioxide. The magnitude of expansion and contraction of wetlands is likely to increase in response to greater severity of precipitation and drought events predicted by climate change models. Increased severity of precipitation and drought events will result in greater variability in size and ephemerality of wetlands. One possible outcome of these size fluctuations is the increase in the anoxic areas preferred by methanogens. Thus, it is becoming increasingly important to discover how production of methane may change as conditions vary. Our objective was to investigate how wetland dynamics, including variability in size and ephemerality, affect methanogenesis and influence the underlying microbial community. We sampled soil from three wetlands of differing ephemerality on the St. Olaf Natural Lands. We measured water and KCl-extractable NO3 and NH4 and used chloroform-fumigation direct-extraction (CFDE) to estimate microbial biomass in each soil sample. Subsamples of each core were incubated in bottles under anoxic conditions in the dark to measure rate of methane production. Bottles were incubated for 9 weeks and headspace samples were collected after 2, 24, and 48 hours and 1 week, and then weekly thereafter. Headspace samples were analyzed for CH4 to calculate rates of methanogenesis. The rate of methane production over the first 48 hours was positively correlated with soil moisture, and negatively correlated with nitrate levels. At the end of the incubation period, methane production was not related to moisture and nitrate, and was positively correlated with soil organic matter. In addition, we observed a lag time before the onset of significant methane flux, followed by a rapid increase in concentration. This lag time was shorter in wet soils than in dry soils. These data suggest that wet, low-nitrate soils

  3. A comparative study of dried apple using hot air, intermittent and continuous microwave: evaluation of kinetic parameters and physicochemical quality attributes

    OpenAIRE

    Aghilinategh, Nahid; Rafiee, Shahin; Gholikhani, Abolfazl; Hosseinpur, Soleiman; Omid, Mahmoud; Mohtasebi, Seyed S.; Maleki, Neda

    2015-01-01

    Abstract In the study, the effectiveness of intermittent (IMWD) and continuous (CMWD) microwave drying and hot air drying (HAD) treatments on apple slices were compared in terms of drying kinetics (moisture diffusivity and activation energy) and critical physicochemical quality attributes (color change, rehydration ratio, bulk density, and total phenol content (TPC) of the final dried product. The temperature, microwave power, air velocity, and pulse ratio (PR) applied in the experiments were...

  4. High Efficiency Liquid-Desiccant Regenerator for Air Conditioning and Industrial Drying

    Energy Technology Data Exchange (ETDEWEB)

    Andrew Lowenstein

    2005-12-19

    Over 2 quads of fossil fuels are used each year for moisture removal. This includes industrial and agricultural processes where feedstocks and final products must be dried, as well as comfort conditioning of indoor spaces where the control of humidity is essential to maintaining healthy, productive and comfortable working conditions. Desiccants, materials that have a high affinity for water vapor, can greatly reduce energy use for both drying and dehumidification. An opportunity exists to greatly improve the competitiveness of advanced liquid-desiccant systems by increasing the efficiency of their regenerators. It is common practice within the chemical process industry to use multiple stage boilers to improve the efficiency of thermal separation processes. The energy needed to regenerate a liquid desiccant, which is a thermal separation process, can also be reduced by using a multiple stage boiler. In this project, a two-stage regenerator was developed in which the first stage is a boiler and the second stage is a scavenging-air regenerator. The only energy input to this regenerator is the natural gas that fires the boiler. The steam produced in the boiler provides the thermal energy to run the second-stage scavenging-air regenerator. This two-stage regenerator is referred to as a 1?-effect regenerator. A model of the high-temperature stage of a 1?-effect regenerator for liquid desiccants was designed, built and successfully tested. At nominal operating conditions (i.e., 2.35 gpm of 36% lithium chloride solution, 307,000 Btu/h firing rate), the boiler removed 153 lb/h of water from the desiccant at a gas-based efficiency of 52.9 % (which corresponds to a COP of 0.95 when a scavenging-air regenerator is added). The steam leaving the boiler, when condensed, had a solids concentration of less than 10 ppm. This low level of solids in the condensate places an upper bound of about 6 lb per year for desiccant loss from the regenerator. This low loss will not create

  5. Urban air temperature anomalies and their relation to soil moisture observed in the city of Hamburg

    Directory of Open Access Journals (Sweden)

    Sarah Wiesner

    2014-09-01

    Full Text Available The spatial variability of the urban air temperature for the city of Hamburg is analyzed based upon a one-year dataset of meteorological and pedological measurements. As local air temperature anomalies are subject to land-use and surface cover, they are monitored by a network of measurement stations within three different urban structures. Mean annual temperature deviations are found to be +1.0K$+1.0\\,\\text{K}$ for inner city sites and +0.25K$+0.25\\,\\text{K}$ to -0.2K$-0.2\\,\\text{K}$ for suburban sites compared to a rural reference. The nocturnal urban heat island (UHI is identified and averages +1.7K$+1.7\\,\\text{K}$ at the inner city stations, +0.7K$+0.7\\,\\text{K}$ at a suburban district housing area and +0.3K$+0.3\\,\\text{K}$ at a nearby green space. The observed UHI effect is most prominent when the wind speed is low (≤2ms-1$\\leq2\\,\\text{ms}^{-1}$ and the sky is only partly cloudy (≤6∕8th$\\leq6/8^{\\text{th}}$. In spring 2011 an average inner city UHI of up to +5.2K$+5.2\\,\\text{K}$ is observed during situations matching these conditions, while the extraordinary dry fall of 2011 lead to remarkably high air temperature differences at all observed stations. As expected, no evidence for a significant impact of topsoil moisture on nighttime UHI effect is found. The analysis of air temperature anomalies during daytime results in an annual mean deviation of -0.5K$-0.5\\,\\text{K}$ above unsealed, vegetated surfaces from a sealed site during days with a turbulent mixing induced by wind speed >2ms-1$>2\\,\\text{ms}^{-1}$. Here, there is an indication for a relation between the water content of upper soil layers and the warming of air: 11 to 17 % of the variance of the diurnal air temperature span is found to be explained by the soil water content for selected relevant days.

  6. Conceptual design of air sparge/soil vent systems for in situ remediation of petroleum hydrocarbons

    International Nuclear Information System (INIS)

    A conceptual design for a sparge and vent system is presented. A sparge and vent system consists of air sparging or in situ aeration in combination with soil vapor extraction. With air sparging, a compressed air source provides sparging of the ground water through aeration points, volatizes dissolved hydrocarbons, and elevates dissolved oxygen (DO) levels in the ground water. Volatile hydrocarbon vapors migrate more readily than liquid in soil, and are extracted to atmosphere with the vapor extraction system. Increased oxygen levels in the ground water and unsaturated soil promotes natural, aerobic biodegradation of the hydrocarbons without nutrient addition. Design considerations for sparge systems include spacing and depth of installation of the sparging points, air injection rates and pressures and the air source. The design techniques for the soil vapor extraction system have been discussed extensively in the literature but generally involve spacing of the extraction wells to capture all the hydrocarbons stripped from the ground water. The soil vapor extraction system can also be modified to enhance oxygen (air) delivery to the unsaturated zone and thus promote natural biodegradation of the petroleum hydrocarbons in the soil. Techniques for monitoring the progress of remediation include measurement of oxygen and carbon dioxide levels in the soil, DO levels in the ground water, subsurface air pressures and petroleum hydrocarbon levels in the discharged air, soil and ground water

  7. Small-angle neutron scattering investigation of polyurethane aged in dry and wet air

    Directory of Open Access Journals (Sweden)

    Q. Tian

    2014-05-01

    Full Text Available The microstructures of Estane 5703 aged at 70°C in dry and wet air have been studied by small-angle neutron scattering. The samples were swollen in deuterated toluene for enhancing the contrast. The scattering data show the characteristic domain structure of polyurethanes consisting of soft and hard segments. Debye-Anderson-Brumberger function used with hard sphere structure factor, and the Teubner-Strey model are used to analyze the two-phase domain structure of the polymer. The combined effects of temperature and humidity have a strong disruption effect on the microstructures of Estane. For the sample aged at 70°C in wet air for 1 month, the domain size, described by the correlation length, increases from 2.3 to 3.8 nm and their distance, expressed by hard-sphere interaction radius, increases from 8.4 to 10.6 nm. The structure development is attributed to degradation of polymer chains as revealed by gel permeation chromatography. The hydrolysis of ester links on polymer backbone at 70°C in the presence of water humidity is the main reason for the changes of the microstructure. These findings can contribute to developing predictive models for the safety, performance, and lifetime of polyurethanes.

  8. Direct observation of local xylem embolisms induced by soil drying in intact Zea mays leaves

    Science.gov (United States)

    Ryu, Jeongeun; Hwang, Bae Geun; Kim, Yangmin X.; Lee, Sang Joon

    2016-01-01

    The vulnerability of vascular plants to xylem embolism is closely related to their stable long-distance water transport, growth, and survival. Direct measurements of xylem embolism are required to understand what causes embolism and what strategies plants employ against it. In this study, synchrotron X-ray microscopy was used to non-destructively investigate both the anatomical structures of xylem vessels and embolism occurrence in the leaves of intact Zea mays (maize) plants. Xylem embolism was induced by water stress at various soil drying periods and soil water contents. X-ray images of dehydrated maize leaves showed that the ratio of gas-filled vessels to all xylem vessels increased with decreased soil water content and reached approximately 30% under severe water stress. Embolism occurred in some but not all vessels. Embolism in maize leaves was not strongly correlated with xylem diameter but was more likely to occur in the peripheral veins. The rate of embolism formation in metaxylem vessels was higher than in protoxylem vessels. This work has demonstrated that xylem embolism remains low in maize leaves under water stress and that there xylem has characteristic spatial traits of vulnerability to embolism. PMID:26946123

  9. Natural radioactivity content in soil and indoor air of Chellanam

    International Nuclear Information System (INIS)

    Contribution of terrestrial radiation due to the presence of naturally occurring radionuclides in soil and air constitutes a significant component of the background radiation exposure to the population. The concentrations of natural radionuclides in the soil and indoor air of Chellanam were investigated with an aim of evaluating the environmental radioactivity level and radiation hazard to the population. Chellanam is in the suburbs of Cochin, with the Arabian Sea in the west and the Cochin backwaters in the east. Chellanam is situated at ∼25 km from the sites of these factories. The data obtained serve as a reference in documenting changes to the environmental radioactivity due to technical activities. Soil samples were collected from 30 locations of the study area. The activity concentrations of 232Th, 238U and 40K in the samples were analysed using gamma spectrometry. The gamma dose rates were calculated using conversion factors recommended by UNSCEAR [United Nations Scientific Committee on the Effects of Atomic Radiation. Sources and effects of ionizing radiation. UNSCEAR (2000)]. The ambient radiation exposure rates measured in the area ranged from 74 to 195 nGy h-1 with a mean value of 131 nGy h-1.The significant radionuclides being 232Th, 238U and 40K, their activities were used to arrive at the absorbed gamma dose rate with a mean value of 131 nGy h-1 and the radium equivalent activity with a mean value of 162 Bq kg-1. The radon progeny levels varied from 0.21 to 1.4 mWL with a mean value of 0.6 mWL. The thoron progeny varied from 0.34 to 2.9 mWL with a mean value of 0.85 mWL. The ratio between thoron and radon progenies varied from 1.4 to 2.3 with a mean of 1.6. The details of the study, analysis and results are discussed. (authors)

  10. Air-drying of cells, the novel conditions for stimulated synthesis of triacylglycerol in a Green Alga, Chlorella kessleri.

    Directory of Open Access Journals (Sweden)

    Takuma Shiratake

    Full Text Available Triacylglycerol is used for the production of commodities including food oils and biodiesel fuel. Microalgae can accumulate triacylglycerol under adverse environmental conditions such as nitrogen-starvation. This study explored the possibility of air-drying of green algal cells as a novel and simple protocol for enhancement of their triacylglycerol content. Chlorella kessleri cells were fixed on the surface of a glass fibre filter and then subjected to air-drying with light illumination. The dry cell weight, on a filter, increased by 2.7-fold in 96 h, the corresponding chlorophyll content ranging from 1.0 to 1.3-fold the initial one. Concomitantly, the triacylglycerol content remarkably increased to 70.3 mole% of fatty acids and 15.9% (w/w, relative to total fatty acids and dry cell weight, respectively, like in cells starved of nitrogen. Reduction of the stress of air-drying by placing the glass filter on a filter paper soaked in H2O lowered the fatty acid content of triacylglycerol to 26.4 mole% as to total fatty acids. Moreover, replacement of the H2O with culture medium further decreased the fatty acid content of triacylglycerol to 12.2 mole%. It thus seemed that severe dehydration is required for full induction of triacylglycerol synthesis, and that nutritional depletion as well as dehydration are crucial environmental factors. Meanwhile, air-drying of Chlamydomonas reinhardtii cells increased the triacylglycerol content to only 37.9 mole% of fatty acids and 4.8% (w/w, relative to total fatty acids and dry cell weight, respectively, and a marked decrease in the chlorophyll content, on a filter, of 33%. Air-drying thus has an impact on triacylglycerol synthesis in C. reinhardtii also, however, the effect is considerably limited, owing probably to instability of the photosynthetic machinery. This air-drying protocol could be useful for the development of a system for industrial production of triacylglycerol with appropriate selection of the

  11. Influence of 60Co γ irradiation pre-treatment on characteristics of hot air drying sweet potato slices

    International Nuclear Information System (INIS)

    The influences of irradiation, hot air temperature and thicknesses of the slices on the characters of dehydration and surface temperature of 60Co γ-rays irradiated sweet potato were investigated. Meanwhile, microscopic observation and determination of water activity of irradiated sweet potato were conducted. The results show that the drying rate and the surface temperature rose with the increasing of irradiation dose. When the dry basis moisture content was 150%, the drying rate of the samples were 1.92, 1.97, 2.05, 2.28, 3.12% /min while the irradiation dose were 0, 2, 5, 8, 10 kGy, and the surface temperature were 48.5 ℃, 46.3℃, 44.5 ℃, 42.2 ℃, 41.5 ℃, respectively. With higher air temperature and thinner of the sweet potato slices, the dehydration of the irradiated sweet potato slices were faster. The drying speed of sweet potato slices at 85 ℃ was 170 min faster than that of 65 ℃. The drying speed of 7 mm sweet potato slices was 228 min faster than that of 3 mm sample. The cell wall and the vacuole of the sweet potato slices were broken after irradiation, and its water activity increased with the increase is radiation dose. The water activity of the irradiated samples were 0.92, 0.945, 0.958, 0.969, 0.979 with the irradiation doses of 0, 2, 5, 8, 10 kGy, respectively. The hot air drying rate, surface temperature and water activity of sweet potato are significantly impacted by irradiation. The conclusion provides a theoretical foundation for further processing technology of combined radiation and hot air drying sweet potato. (authors)

  12. Influence of prevailing disturbances on soil biology and biochemistry of montane habitats at Nanda Devi Biosphere Reserve, India during wet and dry seasons

    DEFF Research Database (Denmark)

    Singh, S.K.; Singh, Anoop; Rai, J.P.N.

    2011-01-01

    The impact of prevailing disturbances in montane habitats of Nanda Devi Biosphere Reserve (NDBR) was studied on soil microbial population, biomass, soil respiration and enzyme activities during wet and dry seasons. The physico-chemical characteristics of soils exhibited conspicuous variation in...... day− 1 and 4.8 μg g− 1 day− 1) in intact forest soil during dry season. The bacterial and fungal populations were also highest in grazed meadow soil followed by disturbed forest, residential area and lowest in intact forest soil, especially in wet season. The soil respiration and enzyme activities...... (dehydrogenase and alkaline phosphatase) were found maximum in grazed meadow soil during wet season and minimum in intact forest soil during dry season. Correlation analysis among variables at different sites revealed significant and positive correlation among soil organic matter, microbial biomass and...

  13. Estimating saturated hydraulic conductivity and air permeability from soil physical properties using state-space analysis

    DEFF Research Database (Denmark)

    Poulsen, Tjalfe; Møldrup, Per; Nielsen, Don;

    2003-01-01

    Estimates of soil hydraulic conductivity (K) and air permeability (k(a)) at given soil-water potentials are often used as reference points in constitutive models for K and k(a) as functions of moisture content and are, therefore, a prerequisite for predicting migration of water, air, and dissolved...... and gaseous chemicals in the vadose zone. In this study, three modeling approaches were used to identify the dependence of saturated hydraulic conductivity (K-S) and air permeability at -100 cm H2O soil-water potential (k(a100)) on soil physical properties in undisturbed soil: (i) Multiple regression......, (ii) ARIMA (autoregressive integrated moving average) modeling, and (iii) State-space modeling. In addition to actual soil property values, ARIMA and state-space models account for effects of spatial correlation in soil properties. Measured data along two 70-m-long transects at a 20-year old...

  14. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    OpenAIRE

    Oikawa, P. Y.; C. Ge; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D.A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whethe...

  15. The influence of soils on heterotrophic respiration exerts a strong control on net ecosystem productivity in seasonally dry Amazonian forests

    OpenAIRE

    J. R. Melton; Shrestha, R. K.; V. K. Arora

    2015-01-01

    Net ecosystem productivity of carbon (NEP) in seasonally dry forests of the Amazon varies greatly between sites with similar precipitation patterns. Correctly modeling the NEP seasonality with terrestrial ecosystem models has proven difficult. Previous modelling studies have mostly advocated for incorporating processes that act to reduce water stress on gross primary productivity (GPP) during the dry season, such as deep soils and roots, plant-mediated hydr...

  16. The Influence of Mastication on Soils and Fuels in Moist and Dry Forests of the Northern Rocky Mountains

    OpenAIRE

    Jain, Theresa; Graham, Russel T.

    2009-01-01

    We evaluated the applicability of mastication as a fuel treatment alternative within Northern Rocky Mountain moist and dry forests to treat post-harvest activity slash (moist forest) and standing trees (dry forest). On the moist forest site, we compared four different slash treatments, mastication, machine grapple piling, lop and scatter, and a control within a wildland urban interface setting to determine the effects of these treatments on soil nutrition, forest floor depth, and woody debris...

  17. Soil-Air Partitioning of Polychlorinated Biphenyls and Total Dichloro-Diphenyl-Trichloroethanes

    Institute of Scientific and Technical Information of China (English)

    Yaping Zhang; Erping Bi; Honghan Chen

    2014-01-01

    Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls (PCBs) and total dichloro-diphenyl-trichloroethanes (p,p’-and o,p’-isomers of DDT, DDD, and DDE) are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients (KSA), and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer (ΔHSA). For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or-ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela-tive humidity in soils. The linear trend between KSA and temperature (T) changes at 0 °C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter (T, organic carbon fraction (fOC), and octanol-air partition coefficient (KOA)) model is put forward to predict the KSA values for PCBs and total DDTs.

  18. A determination of the greenhouse parameter for dry and unpolluted air

    Energy Technology Data Exchange (ETDEWEB)

    Penaloza M, Marcos A. [Universidad de Los Andes, Facultad de Ciencias, Departamento de Fisica, Merida, (Venezuela)

    1996-04-01

    The relative extinction of solar and infrared radiation by dry and clean air molecules, has been estimated through a theoretical determination of the ratio referred ordinarily as the Greenhouse Parameter (GP). In a first approach, it was calculated assuming that terrestrial air only consists of a simple mixture of oxygen and nitrogen. The method used here is based on the application, in an inverse procedure, of an homogeneous, plane-parallel, and time-independent grey model, which employs the Eddington approximation as a solution to the radiative transfer equation, both in the solar and the infrared spectral regions and, which has the GP value as an input free parameter. The best value of the GP was estimated calibrating the local temperature profile for four types of uniform surface (snow, desert, vegetation and ocean), with average albedos known in these spectral regions, adopting air surface temperature values which were chosen for an assumed micro or local climatological environment according to an average radiative criterion. With this result, it was possible for an estimation of the infrared opacity for the air layer implicated in this model and also the mean extinction coefficient in this spectral range to be calculated. The results predicted are compared with results obtained indirectly from the data provided by other authors. Although its validation is constrained solely to the radiative model applied it seems that the value of the GP obtained is more accurate than the one initially available. [Spanish] La extincion relativa de radiacion por moleculas de aire limpio y seco, tanto en la region espectral solar como en la infrarroja, ha sido estimada a traves del calculo teorico de un parametro conocido en general como Parametro de Invernadero (PI). En una primera aproximacion, este parametro fue calculado considerando el aire terrestre como una mezcla simple de oxigeno y nitrogeno solamente. El metodo usado aqui se baso en la aplicacion, bajo un

  19. Numerical-analytical investigation into impact pipe driving in soil with dry friction. Part II: Deformable external medium

    CERN Document Server

    Aleksandrova, Nadezhda

    2013-01-01

    Under analysis is travel of P-waves in an elastic pipe partly embedded in soil with dry friction. The mathematical formulation of the problem on impact pipe driving in soil is based on the model of axial vibration of an elastic bar, considering lateral resistance described using the law of solid dry friction. The author solves problems on axial load on pipe in interaction with external elastic medium, and compares the analytical and numerical results obtained with and without accounting for the external medium deformability.

  20. Soil Water Retention and Relative Permeability for Conditions from Oven-Dry to Full Saturation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. F.

    2011-11-04

    Common conceptual models for unsaturated flow often rely on the oversimplified representation of medium pores as a bundle of cylindrical capillaries and assume that the matric potential is attributed to the capillary force only. The adsorptive surface forces are ignored. It is often assumed that aqueous flow is negligible when a soil is near or at the residual water content. These models are successful at high and medium water contents but often give poor results at low water contents. These models do not apply to conditions at which the water content is less than the residual water content. We extend the lower bound of existing water-retention functions and conductivity models from residual water content to the oven-dry condition (i.e., zero water content) by defining a state-dependent, residual-water content for a soil drier than a critical value. Furthermore, a hydraulic conductivity model for smooth uniform spheres was modified by introducing a correction factor to describe the film flow-induced hydraulic conductivity for natural porous media. The total unsaturated hydraulic conductivity is the sum of those due to capillary and film flow. The extended retention and conductivity models were verified measurements. Results show that, when the soil is at high and intermediate water content, there is no difference between the un-extended and the extended models; when the soil is at low water content, the un-extended models overestimate the water content but underestimate the conductivity. The extended models match the retention and conductivity measurements well.

  1. Nitrogen dynamics in the soil-plant system under deficit and partial root-zone drying irrigation strategies in potatoes

    DEFF Research Database (Denmark)

    Shahnazari, Ali; Ahmadi, Seyed Hamid; Lærke, Poul Erik;

    2008-01-01

    Experiments were conducted in lysimeters with sandy soil under an automatic rain-out shelter to study the effects of subsurface drip irrigation treatments, full irrigation (FI), deficit irrigation (DI) and partial root-zone drying (PRD), on nitrogen (N) dynamics in the soil-plant system of potatoes....... In 2005, FI and PRD2 were investigated, where FI plants received 100% of evaporative demands, while PRD2 plants received 70% water of FI at each irrigation event after tuber initiation. In 2006, besides FI and PRD2 treatments, DI and PRDI receiving 70% water of FI during the whole season were also...... investigated water saving irrigation strategies (PRD1, PRD2, DI) PRD imposedjust after tuber initiation until maturity (PRD2) was the only strategy able to maintain yield; thus, soil drying induced by PRD or DI treatments should be avoided during early growth stages; (2) the PRD and DI treatments improved soil...

  2. Aerosol Particles from Dried Salt-Lakes and Saline Soils Carried on Dust Storms over Beijing

    Directory of Open Access Journals (Sweden)

    Xingying Zhang

    2009-01-01

    Full Text Available Characteristics of individual particles from a super dust storm (DS on 20 March 2002, and those of non dust storm aero sols for Beijing (NDS and Duolun (DL (a desert area are determined using a variety of methods. In China, typically the source of aero sols in dust storms is thought to be deserts with alumino silicates being the main constituent particles; how ever, this does not reflect a complete analysis with our evidence indicating potential alternate dust sources along the _ trans port path. Individual particle anal y sis of aero sols collected from a super dust storm on 20 March 2002 in Beijing shows that among all the 14 elements measured, only S and Cl have re mark able positive correlation. 82.5% of all particles measured contained both S and Cl, and the relative mass per cent age of S and Cl in these particles is much higher than the average of all particles. 62.0% of all particles contained S, Cl, and Na, in which the concentration of Na is 1.4 times higher than average. PMF (Positive Matrix Factorization anal y sis indicates that NaCl and Na2SO4 are major components of these particles with S and Cl showing significant positive correlation. More over, SO4 2- and Cl- also show significant positive correlation in bulk aero sol analysis. XPS (X-ray Pho to electron Spectros copy analysis of the surface of aero sols demonstrates that concentrations of Na and S on particles from the dust storm are higher than those from non-dust storm particles in Beijing and also for particles from. It is very likely that particles enriched with S, Cl, and Na is from the surface soils of dried salt-lakes and saline soils enriched with chloride and sulfate. This evidence demonstrates that be sides deserts, surface soils from dry salt-lakes and saline soils of arid and semi-arid areas are also sources of particulates in dust storms over Beijing.

  3. Impact of Different Methodologies on the Detection of Point Mutations in Routine Air-dried Fine Needle Aspiration (FNA) Smears

    DEFF Research Database (Denmark)

    Rehfeld, C; Münz, S; Krogdahl, A;

    2013-01-01

    extracted from 110 routine air-dried FNA smears and the corresponding surgically obtained formalin-fixed paraffin-embedded tissues. The presence of BRAF, NRAS, HRAS, and KRAS mutations was assessed by real-time PCRs and high resolution melting analysis, and/or pyrosequencing in comparison to real-time PCRs...

  4. Assessing the ability of mechanistic volatilization models to simulate soil surface conditions: a study with the Volt'Air model.

    Science.gov (United States)

    Garcia, L; Bedos, C; Génermont, S; Braud, I; Cellier, P

    2011-09-01

    Ammonia and pesticide volatilization in the field is a surface phenomenon involving physical and chemical processes that depend on the soil surface temperature and water content. The water transfer, heat transfer and energy budget sub models of volatilization models are adapted from the most commonly accepted formalisms and parameterizations. They are less detailed than the dedicated models describing water and heat transfers and surface status. The aim of this work was to assess the ability of one of the available mechanistic volatilization models, Volt'Air, to accurately describe the pedo-climatic conditions of a soil surface at the required time and space resolution. The assessment involves: (i) a sensitivity analysis, (ii) an evaluation of Volt'Air outputs in the light of outputs from a reference Soil-Vegetation-Atmosphere Transfer model (SiSPAT) and three experimental datasets, and (iii) the study of three tests based on modifications of SiSPAT to establish the potential impact of the simplifying assumptions used in Volt'Air. The analysis confirmed that a 5 mm surface layer was well suited, and that Volt'Air surface temperature correlated well with the experimental measurements as well as with SiSPAT outputs. In terms of liquid water transfers, Volt'Air was overall consistent with SiSPAT, with discrepancies only during major rainfall events and dry weather conditions. The tests enabled us to identify the main source of the discrepancies between Volt'Air and SiSPAT: the lack of gaseous water transfer description in Volt'Air. They also helped to explain why neither Volt'Air nor SiSPAT was able to represent lower values of surface water content: current classical water retention and hydraulic conductivity models are not yet adapted to cases of very dry conditions. Given the outcomes of this study, we discuss to what extent the volatilization models can be improved and the questions they pose for current research in water transfer modeling and parameterization

  5. Carbon balance of surfaces vs. ecosystems: advantages of measuring eddy covariance and soil respiration simultaneously in dry grassland ecosystems

    OpenAIRE

    Nagy, Z.; Pintér, K.; Pavelka, M; E. Darenová; Balogh, J.

    2011-01-01

    An automated open system for measurement of soil CO2 efflux (Rsc) was developed and calibrated against known fluxes and tested in the field, while measuring soil respiration also by the gradient method (Rsg) at a dry sandy grassland (Bugac, Hungary). Ecosystem respiration (Reco) was measured by the eddy covariance technique. Small chamber size (5...

  6. [A spatial heterogeneity of surface soil moisture content in dry season in Mulun National Natural Reserve in Karst area].

    Science.gov (United States)

    Song, Tong-qing; Peng, Wan-xia; Zeng, Fu-ping; Ouyang, Zi-wen; Wu, Hai-yong

    2009-01-01

    By the methods of classical statistics and geostatistics, the spatial heterogeneity of surface soil (0-5 cm and 5-10 cm layers) moisture content in dry season in the typical sloping fields and depressions in Mulun National Natural Reserve in Karst area were studied. The results indicated that in study area, the surface soil moisture content in dry season was still higher, and showed a fine semivariogram structure as a whole. The spatial distribution of moisture content in 0-5 cm and 5-10 cm soil layers, both for sloping fields and for depressions, fitted exponential model well. Under the same stand conditions, the moisture content in the two soil layers had the similar spatial structure and distribution pattern; while under different stand conditions, there existed obvious difference in the same soil layer. The spatial pattern of surface soil moisture content in sloping fields was characterized by medium spatial autocorrelation, clear patches with well continuum, relatively slow variation of Moran's I index, while that in depressions was characterized by strong spatial autocorrelation, larger variation of Moran' s I index, and more fragmented patches. Therefore, topography, micro-physiognomy, precipitation, human disturbance, and especially vegetation were the most important factors affecting the spatial pattern of soil moisture content in the Mulun National Natural Reserve, and to preserve primary forest should have favorable effect on the regulation of the spatial heterogeneity of soil moisture content in the Reserve. PMID:19449572

  7. Density-corrected models for gas diffusivity and air permeability in unsaturated soil

    DEFF Research Database (Denmark)

    Deepagoda Thuduwe Kankanamge Kelum, Chamindu; Møldrup, Per; Schjønning, Per;

    2011-01-01

    profile data (total of 150 undisturbed soil samples) were used to investigate soil type and density effects on the gas transport parameters and for model development. The measurements were within a given range of matric potentials (-10 to -500 cm H2O) typically representing natural field conditions in...... diffusivity and to some extent also on air permeability. We developed a density-corrected (D-C) Dp(e)/Do model as a generalized form of a previous model for Dp/ Do at -100 cm H2O of matric potential (Dp,100/Do). The D-C model performed well across soil types and density levels compared with existing models......Accurate prediction of gas diffusivity (Dp/Do) and air permeability (ka) and their variations with air-filled porosity (e) in soil is critical for simulating subsurface migration and emission of climate gases and organic vapors. Gas diffusivity and air permeability measurements from Danish soil...

  8. Airborne bacterial populations above desert soils of the McMurdo Dry Valleys, Antarctica.

    Science.gov (United States)

    Bottos, Eric M; Woo, Anthony C; Zawar-Reza, Peyman; Pointing, Stephen B; Cary, Stephen C

    2014-01-01

    Bacteria are assumed to disperse widely via aerosolized transport due to their small size and resilience. The question of microbial endemicity in isolated populations is directly related to the level of airborne exogenous inputs, yet this has proven hard to identify. The ice-free terrestrial ecosystem of Antarctica, a geographically and climatically isolated continent, was used to interrogate microbial bio-aerosols in relation to the surrounding ecology and climate. High-throughput sequencing of bacterial ribosomal RNA (rRNA) genes was combined with analyses of climate patterns during an austral summer. In general terms, the aerosols were dominated by Firmicutes, whereas surrounding soils supported Actinobacteria-dominated communities. The most abundant taxa were also common to aerosols from other continents, suggesting that a distinct bio-aerosol community is widely dispersed. No evidence for significant marine input to bioaerosols was found at this maritime valley site, instead local influence was largely from nearby volcanic sources. Back trajectory analysis revealed transport of incoming regional air masses across the Antarctic Plateau, and this is envisaged as a strong selective force. It is postulated that local soil microbial dispersal occurs largely via stochastic mobilization of mineral soil particulates. PMID:24121801

  9. Seasonal exposure to drought and air warming affects soil Collembola and mites.

    Directory of Open Access Journals (Sweden)

    Guo-Liang Xu

    Full Text Available Global environmental changes affect not only the aboveground but also the belowground components of ecosystems. The effects of seasonal drought and air warming on the genus level richness of Collembola, and on the abundance and biomass of the community of Collembola and mites were studied in an acidic and a calcareous forest soil in a model oak-ecosystem experiment (the Querco experiment at the Swiss Federal Research Institute WSL in Birmensdorf. The experiment included four climate treatments: control, drought with a 60% reduction in rainfall, air warming with a seasonal temperature increase of 1.4 °C, and air warming + drought. Soil water content was greatly reduced by drought. Soil surface temperature was slightly increased by both the air warming and the drought treatment. Soil mesofauna samples were taken at the end of the first experimental year. Drought was found to increase the abundance of the microarthropod fauna, but reduce the biomass of the community. The percentage of small mites (body length ≤ 0.20 mm increased, but the percentage of large mites (body length >0.40 mm decreased under drought. Air warming had only minor effects on the fauna. All climate treatments significantly reduced the richness of Collembola and the biomass of Collembola and mites in acidic soil, but not in calcareous soil. Drought appeared to have a negative impact on soil microarthropod fauna, but the effects of climate change on soil fauna may vary with the soil type.

  10. The influence of soils on heterotrophic respiration exerts a strong control on net ecosystem productivity in seasonally dry Amazonian forests

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2014-08-01

    Full Text Available Net ecosystem productivity of carbon (NEP in seasonally dry forests of the Amazon varies greatly between sites with similar precipitation patterns. Correctly modeling the NEP seasonality with terrestrial ecosystem models has proven difficult. Previous modelling studies have mostly advocated incorporating processes that act to reduce water stress on gross primary productivity (GPP during the dry season such as including deep soils and roots, plant-mediated hydraulic redistribution of soil moisture, and increased dry season leaf litter generation which reduces leaf age and thus increases photosynthetic capacity. Recent observations, however, indicate that seasonality in heterotrophic respiration also contributes to the observed seasonal cycle of NEP. Here, we use the dynamic vegetation model CLASS-CTEM – without deep soils or roots, hydraulic redistribution of soil moisture or increased dry season litter generation – at two Large-Scale Biosphere–Atmosphere Experiment (LBA sites (Tapajós km 83 and Jarú Reserve. These LBA sites exhibit opposite seasonal NEP cycles despite similar meteorological conditions. Our simulations are able to reproduce the observed NEP seasonality at both sites. Simulated GPP, heterotrophic respiration, latent and sensible heat fluxes, litter fall rate, soil moisture and temperature, and basic vegetation state are also compared with available observation-based estimates which provide confidence that the model overall behaves realistically at the two sites. Our results indicate that appropriately representing the influence of soil texture and depth, through soil moisture, on seasonal patterns of GPP and, especially, heterotrophic respiration is important to correctly simulating NEP seasonality.

  11. High temperature corrosion of cast irons and cast steels in dry air

    Energy Technology Data Exchange (ETDEWEB)

    Tholence, F.; Norell, M. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    2001-07-01

    The oxidation in dry air of four cast alloys intended for exhaust gas systems has been examined. Particular interest was directed to how the oxide growth was related to the microstructures. The examined alloys were two cast ductile irons, a SiMo alloy (Fe3,86Si0,6Mo3C) and a Ni-Resist alloy (Fe32Ni5,3Si2,1C), and two cast stainless steels, one ferritic (Fe18Cr2,1Mn0,32C) and one austenitic (Fe20Cr9Ni0,47C). Coupons were oxidised for 50 h at temperatures between 650 C and 1050 C. The samples were characterised by using XRD, SEM/EDX and AES. As expected, the overall oxide thickness increased with temperature and partial spallation occurred at the highest temperatures for all alloys. Porous Fe oxide nodules nucleate at the graphite nodules on the ductile irons. These Fe-oxide nodules formed above a continuous layer of Fe-Si-oxide for the SiMo and mixed Fe-Ni-Si oxides for the Ni-Resist. The total oxide thickness is about (60 {mu}m). Thick oxides at the interdendritic regions in the cast steels were attributed to non-Cr-carbides. Segregation of Cr directed the formation of iron oxide nodules to the centre of the dendrites in the austenitic alloy. (orig.)

  12. Influence of operating conditions on the air gasification of dry refinery sludge in updraft gasifier

    Science.gov (United States)

    Ahmed, R.; Sinnathambi, C. M.

    2013-06-01

    In the present work, details of the equilibrium modeling of dry refinery sludge (DRS) are presented using ASPEN PLUS Simulator in updraft gasifier. Due to lack of available information in the open journal on refinery sludge gasification using updraft gasifier, an evaluate for its optimum conditions on gasification is presented in this paper. For this purpose a Taguchi Orthogonal array design, statistical software is applied to find optimum conditions for DRS gasification. The goal is to identify the most significant process variable in DRS gasification conditions. The process variables include; oxidation zone temperature, equivalent ratio, operating pressure will be simulated and examined. Attention was focused on the effect of optimum operating conditions on the gas composition of H2 and CO (desirable) and CO2 (undesirable) in terms of mass fraction. From our results and finding it can be concluded that the syngas (H2 & CO) yield in term of mass fraction favors high oxidation zone temperature and at atmospheric pressure while CO2 acid gas favor at a high level of equivalent ratio as well as air flow rate favoring towards complete combustion.

  13. Comparison of halocarbon measurements in an atmospheric dry whole air sample

    Directory of Open Access Journals (Sweden)

    George C. Rhoderick

    2015-11-01

    Full Text Available Abstract The growing awareness of climate change/global warming, and continuing concerns regarding stratospheric ozone depletion, will require continued measurements and standards for many compounds, in particular halocarbons that are linked to these issues. In order to track atmospheric mole fractions and assess the impact of policy on emission rates, it is necessary to demonstrate measurement equivalence at the highest levels of accuracy for assigned values of standards. Precise measurements of these species aid in determining small changes in their atmospheric abundance. A common source of standards/scales and/or well-documented agreement of different scales used to calibrate the measurement instrumentation are key to understanding many sets of data reported by researchers. This report describes the results of a comparison study among National Metrology Institutes and atmospheric research laboratories for the chlorofluorocarbons (CFCs dichlorodifluoromethane (CFC-12, trichlorofluoromethane (CFC-11, and 1,1,2-trichlorotrifluoroethane (CFC-113; the hydrochlorofluorocarbons (HCFCs chlorodifluoromethane (HCFC-22 and 1-chloro-1,1-difluoroethane (HCFC-142b; and the hydrofluorocarbon (HFC 1,1,1,2-tetrafluoroethane (HFC-134a, all in a dried whole air sample. The objective of this study is to compare calibration standards/scales and the measurement capabilities of the participants for these halocarbons at trace atmospheric levels. The results of this study show agreement among four independent calibration scales to better than 2.5% in almost all cases, with many of the reported agreements being better than 1.0%.

  14. Dust particle charge screening in the dry-air plasma produced by an external ionization source

    Energy Technology Data Exchange (ETDEWEB)

    Derbenev, I. N.; Filippov, A. V., E-mail: fav@triniti.ru [State Research Center of the Russian Federation Troitsk Institute for Innovation and Fusion Research (Russian Federation)

    2015-08-15

    The ionic composition of the plasma produced by an external ionization source in dry air at atmospheric pressure and room temperature and the screening of the electric field of a dust particle in such a plasma have been investigated. The point sink model based on the diffusion-drift approximation has been used to solve the screening problem. We have established that the main species of ions in the plasma under consideration are O{sub 4}{sup +}, O{sub 2}{sup -}, and O{sub 4}{sup -} and that the dust particle potential distribution is described by a superposition of four exponentials with four different constants. We show that the first constant coincides with the inverse Debye length, the second is described by the inverse ambipolar diffusion length of the positive and negative plasma components in the characteristic time of their recombination, the third is determined by the conversion of negative ions, and the fourth is determined by the attachment and recombination of electrons and diatomic ions.

  15. EFFECT OF AIR-DRYING ON DEMINERALIZED AND ON SOUND CORONAL HUMAN DENTIN - A STUDY ON DENSITY AND ON LESION SHRINKAGE

    NARCIS (Netherlands)

    ARENDS, J; RUBEN, J

    1995-01-01

    Recently, several papers investigated the linear dimensional changes in dentine after air-drying. This paper pertains to weight changes, volume changes, and density changes caused by air-drying of sound and demineralized intact dentine. The densities of sound and artificially demineralized human cor

  16. Spray washing, absorbent cornstarch powder, and dry time to reduce bacterial numbers on soiled transport cage flooring

    Science.gov (United States)

    Broiler transport cages are often used repeatedly without washing and fecal matter deposited on the floor surface can transfer Campylobacter from one flock to another. Allowing feces to dry is an effective but slow and logistically impractical means to kill Campylobacter in soiled transport cages. ...

  17. A critical evaluation of soil water retention parameterizations with respect to their behaviour near saturation and in the dry range

    Science.gov (United States)

    Madi, Raneem; de Rooij, Gerrit; Mai, Juliane; Mielenz, Henrike

    2016-04-01

    Flow of liquid water and movement of water vapor in the unsaturated zone affect in-soil processes (e.g., root water uptake) and exchanges of water between the soil and the groundwater (e.g., aquifer recharge) and between the soil and the atmosphere (e.g., evaporation). Evapotranspiration in particular is a key factor in the way soils moderate weather and respond to climate change. Soil physicists typically model these processes at scales of individual fields and smaller. They solve Richards' equation using soil water retention curves and hydraulic conductivity curves (soil hydraulic property curves) that are typically valid for even smaller soil volumes. Over the years, many parametric expressions have been proposed as models for the soil hydraulic property curves. Before Richards' equation and the associated soil hydraulic properties can be upscaled or modified for use on scales that are more useful for climate modeling and other applications of practical relevance, the small scale soil hydraulic property curves should at least perform well on the scale for which they were originally developed. Research over the past couple of decades revealed that the fit of soil water retention curves in the dry end is often quite poor, which is particularly risky when vapor flow is a significant factor. It also emerged that the shape of the retention curve for matric potentials very close to zero can generate physically unrealistic behavior of the hydraulic conductivity near saturation when combined with a popular class of conductivity models. We critically examined most of the existing soil water retention parameterizations with respect to these two aspects, and introduced minor modifications to a few of them to improve their performance. The presentation will highlight the results of this review, and demonstrate the effect on calculated fluxes of liquid water and water vapor in soils for illustrative hypothetical scenarios.

  18. Leaf area expansion and dry matter accumulation during establishment of broad bean and sorghum at different temperatures and soil water contents in two types of soil in mediterranean Portugal

    OpenAIRE

    Andrade, José; Abreu, Francisco

    2005-01-01

    Crop establishment is a major factor determining crop productivity in the field and is strongly controlled by soil temperature and soil moisture. Fast leaf expansion and dry matter accumulation during crop establishment are required for an adequate establishment. Leaf area expansion and accumulation of dry matter during the establishment of broad bean (Vicia faba L.) and sorghum (Sorghum vulgare L.) were studied at different soil temperatures and soil moisture contents in a Vertisol (Lisbo...

  19. Soil erosion risk evaluation using GIS in the Yuanmou County,a dry-hot valley of Yunnan, China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Soil erosion is a major threat to sustainable agriculture. Evaluating regional erosion risk is increasingly needed by national and in-ternational environmental agencies. This study elaborates a model (using spatial principal component analysis [SPCA]) method for the evaluation of soil erosion risk in a representative area of dry-hot valley (Yuanmou County) at a scale of 1:100,000 using a spatial database and GIS. The model contains seven factors: elevation, slope, annual precipitation, land use, vegetation, soil, and population density. The evaluation results show that five grades of soil erosion risk: very low, low, medium, high, and very high. These are divided in the study area, and a soil erosion risk evaluation map is created. The model may be applicable to other areas of China because it utilizes spatial data that are generally available.

  20. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    Science.gov (United States)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  1. Testing the USA EPA's ISCST-Version 3 model on dioxins: a comparison of predicted and observed air and soil concentrations

    Science.gov (United States)

    Lorber, Matthew; Eschenroeder, Alan; Robinson, Randall

    The central purpose of our study was to examine the performance of the United States Environmental Protection Agency's (EPA) nonreactive Gaussian air quality dispersion model, the Industrial Source Complex Short-Term Model (ISCST3) Version 98226, in predicting polychlorinated dibenzodioxins and polychlorinated dibenzofurans concentrations (subsequently referred to as dioxins and furans, or CDD/Fs) in both air and soil near the Columbus Municipal Solid Waste-to-Energy Facility (CMSWTE) in Columbus, OH. During its 11 yr operation, the CMSWTE was estimated to be emitting nearly 1 kg of CDD/F Toxic Equivalents (TEQs) per year, making it one of the highest single emitters of dioxin in the United States during its operation. An ambient air-monitoring study conducted in 1994, prior to its shutdown in December of 1994, clearly identified high dioxin air concentration in the downwind direction during two sampling events. In one of the events, the CMSWTE stack was concurrently monitored for dioxins. A soil sampling study conducted in 1995/1996 was similarly able to identify an area of impacted soil extending mainly in the predominant downwind direction up to 3 km from the CMSWTE. Site-specific information, including meteorological data, stack parameters and emission rates, and terrain descriptions, were input into ISCST3 to predict ground-level 48-h concentrations which could be compared with the 48-h measured air concentrations. Predicted annual average dry and wet deposition of particle-bound dioxins were input into a simple soil reservoir model to predict soil concentrations that would be present after 11.5 yr of emissions, which were compared to measured concentrations. Both soil- and air-predicted concentrations were generally within a factor of 10 of observations, and judged to be reasonable given the small number of observations and the uncertainties of the exercise. Principal uncertainties identified and discussed include: source characterization (stack emission

  2. Antioxidant capacity and total phenolic content of air-dried cape gooseberry (physalis peruviana l.) at different ripeness stages

    OpenAIRE

    Narváez-Cuenca, Carlos Eduardo; Mateus-Gómez, Ángela; Restrepo-Sánchez, Luz Patricia

    2014-01-01

    Because the use of drying at high temperatures might negatively affect the functional properties of fruits, the effect of air-drying at 60°C on the total phenolic content (TPC) and antioxidant capacity (AOC) of cape gooseberry fruit was evaluated at three ripeness stages. The AOC was evaluated with 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing ability of plasma (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and β-carotene-linoleate assays. The TPC and AOC incre...

  3. Rain-induced emission pulses of NOx and HCHO from soils in African regions after dry spells as viewed by satellite sensors

    Science.gov (United States)

    Zörner, Jan; Penning de Vries, Marloes; Beirle, Steffen; Veres, Patrick; Williams, Jonathan; Wagner, Thomas

    2014-05-01

    Outside industrial areas, soil emissions of NOx (stemming from bacterial emissions of NO) represent a considerable fraction of total NOx emissions, and may even dominate in remote tropical and agricultural areas. NOx fluxes from soils are controlled by abiotic and microbiological processes which depend on ambient environmental conditions. Rain-induced spikes in NOx have been observed by in-situ measurements and also satellite observations. However, the estimation of soil emissions over broad geographic regions remains uncertain using bottom-up approaches. Independent, global satellite measurements can help constrain emissions used in chemical models. Laboratory experiments on soil fluxes suggest that significant HCHO emissions from soil can occur. However, it has not been previously attempted to detect HCHO emissions from wetted soils by using satellite observations. This study investigates the evolution of tropospheric NO2 (as a proxy for NOx) and HCHO column densities before and after the first rain fall event following a prolonged dry period in semi-arid regions, deserts as well as tropical regions in Africa. Tropospheric NO2 and HCHO columns retrieved from OMI aboard the AURA satellite, GOME-2 aboard METOP and SCIAMACHY aboard ENVISAT are used to study and inter-compare the observed responses of the trace gases with multiple space-based instruments. The observed responses are prone to be affected by other sources like lightning, fire, influx from polluted air masses, as well measurement errors in the satellite retrieval caused by manifold reasons such as an increased cloud contamination. Thus, much care is taken verify that the observed spikes reflect enhancements in soil emissions. Total column measurements of H2O from GOME-2 give further insight into the atmospheric state and help to explain the increase in humidity before the first precipitation event. The analysis is not only conducted for averages of distinct geographic regions, i.e. the Sahel, but also

  4. Regional Differences and Characteristics of Soil Organic Carbon Density Between Dry Land and Paddy Field in China

    Institute of Scientific and Technical Information of China (English)

    XU Quan; RUI Wen-yi; BIAN Xin-min; ZHANG Wei-jian

    2007-01-01

    Study on the regional characteristics of soil organic carbon (SOC) density in farmland will not only contribute greatly to the technique of soil productivity enhancement, but also give evidences of technique selection and policy making for carbon sequestration in soils. Based on the second national soil survey of China, the situation of SOC density in the plow layer of farmland was analyzed under different land use patterns. Results showed that SOC density in the plow layer was about 3.15 kg m-2 in average ranging from 0.81 to 12.68 kg m-2. The highest density was found in the southeastern region with an average of 3.63 kg m-2, while the lowest occurring in the northwestern region with an average of 3.00 kg m-2. The variation coefficient of SOC density in the plow layer of farmland was 57%, which was 35% lower than that of non-farmland soils. Compared to SOC density in the dry land, SOC density in paddy soils was 13% higher with a lower variation coefficient between different regions. In addition, the relationships between the climatic factors (annual average temperature and precipitation) and SOC density were lower in farmland than those in non-farmland soils, as well as lower in paddy soils than those in dry land of farmland. These results suggest that anthropogenic disturbances have great impacts on SOC density in farmland soils, especially in paddy soils, indicating that Chinese rice cropping may contribute greatly to the SOC stability and sequestration in paddy field.

  5. Bench-scale feasibility testing of pulsed-air technology for in-tank mixing of dry cementitious solids with tank liquids and settled solids

    International Nuclear Information System (INIS)

    This report documents the results of testing performed to determine the feasibility of using a pulsed-air mixing technology (equipment developed by Pulsair Systems, Inc., Bellevue, WA) to mix cementitious dry solids with supernatant and settled solids within a horizontal tank. The mixing technology is being considered to provide in situ stabilization of the open-quotes Vclose quotes tanks at the Idaho National Engineering and Environmental Laboratory (INEEL). The testing was performed in a vessel roughly 1/6 the scale of the INEEL tanks. The tests used a fine soil to simulate settled solids and water to simulate tank supernatants. The cementitious dry materials consisted of Portland cement and Aquaset-2H (a product of Fluid Tech Inc. consisting of clay and Portland cement). Two scoping tests were conducted to allow suitable mixing parameters to be selected. The scoping tests used only visual observations during grout disassembly to assess mixing performance. After the scoping tests indicated the approach may be feasible, an additional two mixing tests were conducted. In addition to visual observations during disassembly of the solidified grout, these tests included addition of chemical tracers and chemical analysis of samples to determine the degree of mixing uniformity achieved. The final two mixing tests demonstrated that the pulsed-air mixing technique is capable of producing slurries containing substantially more cementitious dry solids than indicated by the formulations suggested by INEEL staff. Including additional cement in the formulation may have benefits in terms of increasing mobilization of solids, reducing water separation during curing, and increasing the strength of the solidified product. During addition to the tank, the cementitious solids had a tendency to form clumps which broke down with continued mixing

  6. Uptake of polychlorinated biphenyls and organochlorine pesticides from soil and air into radishes (Raphanus sativus)

    DEFF Research Database (Denmark)

    Mikes, Ondrej; Cupr, P.; Trapp, Stefan;

    2009-01-01

    Uptake of organochlorine pesticides and polychlorinated biphenyls from soil and air into radishes was measured at a heavily contaminated field site. The highest contaminant concentrations were found for DDT and its metabolites, and for beta-hexachlorocyclohexane. Bioconcentration factor (BCF...

  7. The Research Status and Prospects of the Hot Air Drying and Freeze Drying for Papaya%木瓜热风干燥和冷冻干燥的研究现状和展望

    Institute of Scientific and Technical Information of China (English)

    李铭; 陈冬梅; 侯萍; 赵鹤飞; 余善鸣

    2013-01-01

    果蔬的干燥主要有热干、微波、冻干和组合干燥。木瓜的干燥以热干为主,冻干能最大程度保持木瓜的色泽、风味和营养价值,但研究报道较少。今后木瓜干燥研究的主要内容将是提高品质和降低产品成本。因此,木瓜的热干和冻干的组合干燥将是研究的重点。%The primary drying technologys of fruits and vegetables are hot-air drying , microwave drying , freeze drying and combined drying. The mainly drying method of papaya is hot-air drying. The freeze-dried can keep the greatest degree of color, flavor and nutritional value of papaya, However, it is lack of references on that. Future research of the drying technology of papaya will be improvement of the quality and to reduce product cost. Therefore, the combined drying technology of hot-air and freeze of papaya will become a study emphasis in further research.

  8. Diversity of soil fungi in dry deciduous forest of Bhadra Wildlife Sanctuary, Western Ghats of southern India

    Institute of Scientific and Technical Information of China (English)

    Shivakumar P.Banakar; B.Thippeswamy; B.V.Thirumalesh; K.J.Naveenkumar

    2012-01-01

    We assessed soil fungal diversity in the dry deciduous forest of a Bhadra Wildlife Sanctuary of the Western Ghats (210.31 m a.s.(l).; N 13°44′ and E75°37′).Soil samples were collected by random mixed sampling during winter (November,2008),summer (March,2009) and monsoon (August,2009) seasons,and physico-chemical parameters were recorded.During winter,summer,and monsoon seasons,49,45 and 49of fungal species belongs to 20,18 and 19 of genera were isolated,respectively.Isolated soil fungi were mainly of the Mitosporic fungi,followed by Zygomycotina,Ascomycotina,Oomycotina and Coelomycetes.Indices of diversity,dominance and fisher alpha during winter,summer and monsoon seasons were 3.756,3.638 and 3.738 (H′),0.9737,0.9694and 0.9726 (1-D) and 18.84,29.83 and 19.46 (α),respectivelv.Spearman's (r) correlation coefficient of fungal population with physicochemical parameters of soils showed significantly positive and negative correlations (p<0.01) during winter,summer and monsoon seasons.Physico-chemical soil parameters played an important role in the occurrence,diversity,distribution,and relative abundance of fungal species in the tropical dry deciduous forest soil.

  9. Oxidation behaviour of UZr2.3 alloy in dry air

    International Nuclear Information System (INIS)

    UZr2.3 alloy is being considered as potential material for storage of hydrogen isotopes. However, the performance of this reactive alloy gets largely deteriorated by surface oxidation of oxygen impurity present in the process gas. Hence, it is necessary to investigate the oxidation behaviour of this alloy. In this study, UZr2.3 alloy was prepared by arc melting method followed by vacuum annealing. The alloy was characterized by XRD, SEM and EDX methods. Oxidation behaviour of UZr2.3 alloy was investigated in the temperature range of 773-848 K in dry air by using thermo gravimetric technique. The isothermal oxidation behaviour was studied for 24 hours at each temperature. The oxidation curves are shown. The oxidation curves were analysed using the rate equation: (Δm/a)n = kt, where, (Δm/a) is the mass gain per unit area, n is the power exponent, k is the rate constant and t is time in (seconds). Using the linear rate law, the rate constant (k) of oxidation reaction was evaluated at each temperature after 11% completion of the reaction. Analysis of the results shows that the oxidation reaction follows linear rate law (n ∼ 1) in the temperature range (773-848 K) The variation of (ln k) with reciprocal temperature is shown. The activation energy of this oxidation reaction in the temperature range 773-848 K was calculated using the Arrhenius equation and found to be 162 kJ/mol which is in good agreement with that of literature reported value of 196 kJ/mol

  10. Pan-Arctic linkages between snow accumulation and growing season air temperature, soil moisture and vegetation

    OpenAIRE

    K. A. Luus; Gel, Y.; J. C. Lin; Kelly, R. E. J.; C. R. Duguay

    2013-01-01

    Arctic field studies have indicated that the air temperature, soil moisture and vegetation at a site influence the quantity of snow accumulated, and that snow accumulation can alter growing season soil moisture and vegetation. Climate change is predicted to bring about warmer air temperatures, greater snow accumulation and northward movements of the shrub and tree lines. Understanding the response of northern environments to changes in snow and growing season land surface characteristi...

  11. Aggregate Stability of Purple Soil and Its Impacts on Soil Erosion of Slope Dry Land%紫色土旱坡地土壤团聚体稳定性特征对侵蚀过程的影响

    Institute of Scientific and Technical Information of China (English)

    陈正发; 史东梅; 谢均强; 张兵

    2011-01-01

    [Objective] The objective of this research was to study the purple soil aggregate stability compared with soil erosion in different land use types of dry land. [Method] By using the methods of Simulated Rainfall and analysis characteristics of soil aggregates, the purple soil aggregate stability characteristics of four land use types and their impacts on the process of erosion were studied. [Result] It was found that fast wetting made the majority of aggregate breaking down to the small aggregates. The great impact of two treatments which were slow wetting and wet stirring was the 5-2 mm large aggregates Which the diameter is mainly concentrated in 2-0.5 mm after collapse. The aggregate stability of four land types is mulberry plantation>alfalfa>grassland > vegetable garden. Both the MWD and GMD are the smallest for four land use types of fast wetting, and the largest of the MWD and GMD are slow wetting. The mainly collapse mechanism of soil aggregates in purple soil dry land is fast wetting when the internal air pressure, and the minimal damage is clay swelling. The order of total runoff and sediment in four land use types under simulated rainfall is vegetable land > grassland > alfalfa > mulberry plantation, and the process of runoff and sediment coupled with the aggregate characteristics of stability. The correlation of soil aggregate stability index between runoff rate and sediment yield rate of rainfall is high in the first 1 hour. MWD values under fast wetting were significantly negatively correlated with runoff and sediment erosion. The mainly soil erosion of aggregate crushing mechanism of purple soil in dry land is soil aggregate destruction of the internal air pressure. [Conclusion] The worse the stability of soil aggregates, the more erosion and runoff in purple soil dry land. The relation between soil aggregate stability and sediment characteristics is the highest in antecedent rainfall erosion. It is better to use MWD to reflect the relationship

  12. Drying characteristics of garlic ( Allium sativum L) slices in a convective hot air dryer

    Science.gov (United States)

    Demiray, Engin; Tulek, Yahya

    2014-06-01

    The effects of drying temperatures on the drying kinetics of garlic slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 4.214 × 10-10 to 2.221 × 10-10 m2 s-1 over the temperature range studied, and activation energy was 30.582 kJ mol-1.

  13. Effects of Tomato Geometries and Air Temperature on the Drying Behavior of Plum Tomato

    Directory of Open Access Journals (Sweden)

    M. S. Brooks

    2008-01-01

    Full Text Available The drying behavior of plum tomatoes as affected by drying temperature and tomato pieces geometry was investigated. The tomato was cut into halves, quarters and eighths and dried at temperatures of 55 and 65°C. During drying, the moisture content followed an exponential decay curve with R2>0.98. The time required to achieve the critical moisture content for storage (15% for the tomato halves, quarters and eights were 36, 26 and 20 h and 23, 18 and 13 h, at the temperatures of 55 and 65°C, respectively. The rate of drying also followed exponential decay and was unaffected by the temperature and tomato piece geometries. The specific drying rate was dependent on the drying temperature and was not affected by geometry. The total surface area appeared to have a significant effect on the specific moisture loss than the cut surface area. Cutting the tomato samples into smaller pieces and drying at lower temperatures is recommended to reduce the drying time and maintain quality.

  14. Effects of Slice Processing on Hot Air Drying Characteristics of Semi-dry Original Red Jujube%切片处理对半干红枣热风干燥特性的影响

    Institute of Scientific and Technical Information of China (English)

    韩志慧; 郭婷; 何新益; 程莉莉

    2013-01-01

      The objective of this study was to investigate the effects of slice processing on hot air drying characteristics of semi-dry red jujube. Drying characteristics of red jujube slice and origine semi-dry original red jujube under different hot air drying temperature were compared. The drying kinetics model of red jujube slice and origine semi-dry original red jujube were founded. Results showed that slice processing could decrease the drying time of semi-dry original red jujube. Page model provided better simulation of drying curves for red jujube slice at different hot drying temperature. While Henderson and Pabis model provided better simulation of drying curves for origine semi-dry original red jujube at different hot air drying temperature. The effective moisture diffusivity of red jujube was 10 times that of origine semi-dry original red jujube, among 1.77×10-5 m2/s-2.99×10-5 m2/s and 4.56×10-6 m2/s-7.20×10-6 m2/s, respectively. Slice processing has the significant effects on drying characteristics of semi-dry original red jujube dried by hot air drying.%  为探索切片处理对半干红枣热风干燥特性的影响,以半干原枣果作参照,比较了不同热风干燥温度下枣片和枣果的干燥特性,分别建立了干燥动力学模型。研究结果表明,切片处理可以缩短红枣的干燥时间;枣片的热风干燥过程符合Page方程,而枣果的热风干燥过程符合Henderson and Pabis方程。枣片的有效扩散系数是枣果有效扩散系数的的10倍左右,分别为1.77×10-5 m2/s~2.99×10-5 m2/s、4.56×10-6 m2/s~7.20×10-6 m2/s。结果表明切片处理对红枣的干燥特性有明显的影响。

  15. Influence of carbon monoxide additions on the sensitivity of the dry hydrogen-air mixtures to detonation

    International Nuclear Information System (INIS)

    Under severe accident conditions of water cooled nuclear reactors the hydrogen-air detonation represents one of the most hazardous events which can result in the reactor containment damage. An important factor related with the measure of gas mixture detonability is the detonation cell size which correlates with the critical tube diameter and detonation initiation energy. A numerical kinetic study is presented of the influence of carbon monoxide admixtures (from 0 vol.% to 40 vol.%) upon the sensitivity (detonation cell size) of the dry hydrogen-air gas mixtures to detonation in post-accident containment atmosphere. (author). 3 refs., 3 figs

  16. Modeling of mass transfer performance of hot-air drying of sweet potato (Ipomoea Batatas L. slices

    Directory of Open Access Journals (Sweden)

    Zhu Aishi

    2014-01-01

    Full Text Available In order to investigate the transfer characteristics of the sweet potato drying process, a laboratory convective hot air dryer was applied to study the influences of drying temperature, hot air velocity and thickness of sweet potato slice on the drying process. The experimental data of moisture ratio of sweet potato slices were used to fit the mathematical models, and the effective diffusion coefficients were calculated. The result showed that temperature, velocity and thickness influenced the drying process significantly. The Logarithmic model showed the best fit to experimental drying data for temperature and the Wang and Singh model were found to be the most satisfactory for velocity and thickness. It was also found that, with the increase of temperature from 60 to 80°C, the effective moisture diffusion coefficient varied from 2.962×10-10 to 4.694×10-10 m2×s-1, and it fitted the Arrhenius equation, the activation energy was 23.29 kJ×mol-1; with the increase of hot air velocity from 0.423 to 1.120 m×s-1, the values of effective moisture diffusion coefficient varied from 2.877×10-10 to 3.760×10-10 m2•s-1; with the increase of thickness of sweet potato slice from 0.002 m to 0.004 m, the values of effective moisture diffusion coefficient varied from 3.887×10-10 to 1.225×10-9 m2•s-1.

  17. Role of vegetation cover on soil water balance in two Mediterranean areas: semiarid and dry at southeastern of Spain.

    Science.gov (United States)

    Manrique, Àngela; Ruiz, Samantha; Chirino, Esteban; Bellot, Juan

    2014-05-01

    Water is a limited resource in the semiarid areas, which affects both, the population services, the economic growth, like the natural ecosystems stability. In this context, an accurate knowledge of soil water balance and role of the vegetation cover contribute to improve the management of resources water and forest. These studies are increasingly important, if we consider the latest Assessment Reports of the Intergovernmental Panel on Climate Change. In this paper the main objectives were focused on:(1)To determine the soil water balance on two different climatic conditions, semiarid and dry climate and(2) Assess the effect of vegetation (structure and cover) on soil water balance under the studied climatic conditions. For this purpose we used HYDROBAL ecohydrological model, which calculates at a daily resolution the water flows through of the vegetation canopy, estimates daily soil moisture and predicts deep drainage from the unsaturated soil layer into the aquifer. In order to achieve these objectives, we have selected two sites in the south-eastern of Spain, on soils calcareous and different climatic conditions. Ventós site in a semiarid Mediterranean area and Confrides site in a dry Mediterranean area, with 303 and 611 mm of annual precipitation respectively. Both sites, the predominant vegetation are afforestations with Pinus halepensis on dry grasslands with some patches of thorn shrublands and dwarf scrubs; but it show difference on trees density, cover and height of pines.Soil water balance was determined in each site using HYDROBAL ecohydrological model on one hydrological year (October 2012 and September 2013).Model inputs include climatic variables (daily rainfall and temperature), as well as soil and vegetation characteristics (soil field capacity, soil wilting point, initial soil water content and vegetation cover index). Model outputs are interception, net rainfall, runoff, soil water reserves, actual evapotranspiration, direct percolation, and deep

  18. Availability and evaluation of European forest soil monitoring data in the study on the effects of air pollution on forests

    OpenAIRE

    Cools N; De Vos B

    2011-01-01

    In the study of air pollution effects on forest ecosystems, solid soil data such as cation exchange capacity, base saturation and other exchangeable cation fractions, soil texture, soil moisture, soil weathering rates, C/N ratio and other variables form an important information base for many air pollution impact models. This paper shows some of the possibilities and the limitations of the soil data that European countries collected on the systematic Level I and on the intensive and permanent ...

  19. Oxidation Behavior of a Pd43Cu27Ni10P20 Bulk Metallic Glass and Foam in Dry Air

    Science.gov (United States)

    Kai, W.; Ren, I. F.; Barnard, B.; Liaw, P. K.; Demetriou, M. D.; Johnson, W. L.

    2010-07-01

    The oxidation behavior of both Pd43Cu27Ni10P20 bulk metallic glass (Pd4-BMG) and its amorphous foam containing 45 pct porosity (Pd4-AF) was investigated over the temperature range of 343 K (70 °C) to 623 K (350 °C) in dry air. The results showed that virtually no oxidation occurred in the Pd4-BMG at T Cu3P, and Pd3P.

  20. Drying of fruits and vegetables using a flat plate solar collector with convective air flow

    International Nuclear Information System (INIS)

    This paper presents the analysis of drying of different fruits and vegetables dried by a flat plate solar collector developed at the Department of Agricultural Mechanization, Khyber PukhtunKhwa Agricultural University Peshawar, Pakistan. A small flat plate solar collector is designed and tested for its maximum performance in terms of efficiency with different convective flow rates. The collector assembly is divided into two parts. The flat plate solar collector and the drying chamber. The materials used for flat plate solar collector are wood, steel sheet, Insulation materials, and glass sheet as covering material. The insulation box (0.9 x 1.8 x 0.3 meter) is made up of wood of popular and deodar, to be fully isolated with the help of polystyrene. The absorber is black painted v-corrugated steel sheet. Collector has a tilt angle of 34 deg. (Equivalent to the latitude of Peshawar). The covering material is (0.9 x 1.8 meter) and 5 mm thick glass sheet placed at the top of the wooden box. The collector is supported and tilted with the help of a frame made up of iron angled arms. While the drying chamber is a (1 X 0.5 x 0.3 meter) wooden box connected to the outlet duct of the collector with the help of polyvinylchloride pipe. Experiments were conducted different fruits and vegetables and different parameters like moisture lost by the products in each hour, drying rate at each hour of drying, humidity and temperature of the drying chamber. It was observed that the products such as bitter guard and onion were dried in 10 to 2 hours up to moisture content less then 8%. These two product lost 8% to 10% moisture during each hour of drying. While grapes and Green chili are dried in 24 to 25 hours up to moisture content less then 8%. These two products lost 4% to 5% moisture in each hour of drying. The drying rate of all the products dried was very much consistent. It was observed that onion and bitter guard showed a good drying rate of 0.03[g(H/sub 2/O)/g(d.m).cm/ 2 hr] to

  1. Variation in tensile properties and relationship between tensile properties and air-dried density for moso bamboo

    Institute of Scientific and Technical Information of China (English)

    Huaqiang YU; Benhua FEI; Haiqing REN; Zehui JIANG; Xinge LIU

    2008-01-01

    This research investigated the variation in tensile properties and the relationship between the tensile properties and the air-dried density for the moso bamboo (Phyllostachys pubescens) by sampling at different heights and radial positions. Results showed that the variation of the longitudinal tensile properties in the radial direction was greater than that in the longitudinal direction. The longitudinal tensile modules of elasticity (MOE) ranged from 8.49 to 32.49 GPa. MOE for the outermost layer was 3-4 times as high as that for the innermost layer. The longitudinal tensile strength (MOR) ranged from 115.94 to 328.15 MPa. MOR for the outermost layer is 2-3 times as high as that for the innermost layer. Linear and curvilinear regressions were done from tested data of MOE, MOR and air-dried density in this paper. The linear equation worked a little better than the curvilinear one to predict the longitudinal MOR and MOE from air-dried density.

  2. Quantification of soil-to-plant transport of recombinant nucleopolyhedrovirus: effects of soil type and moisture, air currents, and precipitation.

    Science.gov (United States)

    Fuxa, J R; Richter, A R

    2001-11-01

    Significantly more occlusion bodies (OB) of DuPont viral construct HzSNPV-LqhIT2, expressing a scorpion toxin, were transported by artificial rainfall to cotton plants from sandy soil (70:15:15 sand-silt-clay) than from silt (15:70:15) and significantly more from silt than from clay (15:15:70). The amounts transported by 5 versus 50 mm of precipitation were the same, and transport was zero when there was no precipitation. In treatments that included precipitation, the mean number of viable OB transported to entire, 25- to 35-cm-tall cotton plants ranged from 56 (clay soil, 5 mm of rain) to 226 (sandy soil, 50 mm of rain) OB/plant. In a second experiment, viral transport increased with increasing wind velocity (0, 16, and 31 km/h) and was greater in dry (-1.0 bar of matric potential) than in moist (-0.5 bar) soil. Wind transport was greater for virus in a clay soil than in silt or sand. Only 3.3 x 10(-7) (clay soil, 5 mm rain) to 1.3 x 10(-6) (sandy soil, 50 mm rain) of the OB in surrounding soil in experiment 1 or 1.1 x 10(-7) (-0.5 bar sandy soil, 16-km/h wind) to 1.3 x 10(-6) (-1.0 bar clay soil, 31-km/h wind) in experiment 2 were transported by rainfall or wind to cotton plants. This reduces the risk of environmental release of a recombinant nucleopolyhedrovirus (NPV), because only a very small proportion of recombinant virus in the soil reservoir is transported to vegetation, where it can be ingested by and replicate in new host insects. PMID:11679341

  3. Mathematical modeling of convective air drying of quinoa-supplemented feed for laboratory rats

    Directory of Open Access Journals (Sweden)

    Antonio Vega-Gálvez

    2011-02-01

    Full Text Available Drying kinetics of quinoa-supplemented feed for laboratory rats during processing at 50, 60, 70, 80 and 90ºC was studied and modeled in this work. Desorption isotherm was obtained at 60ºC giving a monolayer moisture content of 0.04 g water/g d.m. The experimental drying curves showed that drying process took place only in the falling rate period. Several thin-layer drying equations available in the literature were evaluated based on determination coefficient (r², sum squared errors (SSE and Chi-square (χ2 statisticals. In comparison to the experimental moisture values, the values estimated with the Logarithmic model gave the best fit quality (r² >0.994, SSE < 0.00015 and χ2 < 0.00018, showing this equation could predict very accurately the drying time of rat feed under the operative conditions applied.

  4. [Influence of Different Straws Returning with Landfill on Soil Microbial Community Structure Under Dry and Water Farming].

    Science.gov (United States)

    Lan, Mu-ling; Gao, Ming

    2015-11-01

    Based on rice, wheat, corn straw and rape, broad bean green stalk as the research object, using phospholipid fatty acid (PLFA) method, combining principal component analysis method to study the soil microbial quantity, distribution of flora, community structure characteristics under dry and water farming as two different cultivated land use types. The PLFA analysis results showed that: under dry farming, total PLFA quantity ranged 8.35-25.15 nmol x g(-1), showed rape > broad bean > corn > rice > wheat, rape and broad bean significantly increased total PLFA quantity by 1.18 and 1.08 times compared to the treatment without straw; PLFA quantity of bacterial flora in treatments with straws was higher than that without straw, and fungal biomass was significantly increased, so was the species richness of microbial community. Under water faming, the treatments of different straws returning with landfill have improved the PLFA quantity of total soil microbial and flora comparing with the treatment without straw, fungi significantly increased, and species richness of microbial communities value also increased significantly. Total PLFA quantity ranged 4.04-22.19 nmol x g(-1), showed rice > corn > wheat > broad bean > rape, which in rape and broad bean treatments were lower than the treatment without straw; fungal PLFA amount in 5 kinds of straw except broad bean treatment was significantly higher than that of the treatment without straw, bacteria and total PLFA quantity in broad bean processing were significantly lower than those of other treatments, actinomycetes, G+, G- had no significant difference between all treatments; rice, wheat, corn, rape could significantly increase the soil microbial species richness index and dominance index under water faming. The results of principal component analysis showed that broad bean green stalk had the greatest impact on the microbial community structure in the dry soil, rape green stalk and wheat straw had the biggest influence on

  5. The repeated drying-wetting and freezing-thawing cycles affect only the active pool of soil organic matter

    Science.gov (United States)

    Semenov, Vyacheslav; Zinyakova, Natalya; Tulina, Anastasiya

    2016-04-01

    The decrease in the content of soil organic carbon, particularly in active form, is one of the major problems of the 21st century, which is closely related to the disturbance of the biogeochemical carbon cycle and to the increase in the emission of carbon dioxide into the atmosphere. The main reasons for the SOM losses are the surplus of the SOM active pool losses due to mineralization, erosion, and infiltration over the input of fresh organic matter to the soil, as well as the changes in the soil conditions and processes due to natural and anthropogenic disturbing impacts. Experiments were carried out with mixed samples from the upper layers of soddy-podzolic soil, gray forest soil, and typical chernozems. Soil samples as controls were incubated after wetting for 150 days. The dynamics and cumulative production of C-CO2 under stable temperature (22°C) and moisture conditions were determined; the initial content of potentially mineralizable organic matter (C0) in the soil at the beginning of the incubation was then calculated to use these data as the control. Other soil samples were exposed in flasks to the following successive treatments: wetting →incubation → freezing → thawing → incubation →drying. Six repeated cycles of disturbing impacts were performed for 140 days of the experiment. After six cycles, the soil samples were incubated under stable temperature and moisture conditions for 150 days. The wetting of dried soils and the thawing of frozen soils are accompanied by the pulsed dynamics of the C-CO2 production with an abrupt increase in the rate of the C-CO2 emission within several days by 2.7-12.4 and 1.6-2.7 times, respectively, compared to the stable incubation conditions. The rate of the C-CO2 production pulses under each subsequent impact decreased compared to the preceding one similarly for all studied soils, which could be due to the depletion in potentially mineralizable soil organic matter (C0). The cumulative extra C-CO2 production by

  6. Water relations and transpiration of quinoa (Chenopodium quinoa Willd.) under salinity and soil drying

    DEFF Research Database (Denmark)

    Razzaghi, Fatemeh; Ahmadi, Seyed Hamid; Adolf, Verena Isabelle;

    2011-01-01

    Drought and salinity are the two major factors limiting crop growth and production in arid and semi-arid regions. The separate and combined effects of salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were studied in a greenhouse experiment. Stomatal conductance (gs), leaf...... reached 0.42 or lower, but under the saline conditions of PD10 and PD20, the threshold values of RAW were 0.67 and 0.96, respectively. In conclusion, due to the additive effect of osmotic and matric potential during soil drying on soil water availability, quinoa should be re-irrigated at higher RAW in...

  7. Combined in-situ and ex-situ bioremediation of petroleum hydrocarbon contaminated soils by closed-loop soil vapor extraction and air injection

    International Nuclear Information System (INIS)

    Treatment and restoration of petroleum hydrocarbon contaminated soils at a bulk petroleum above-ground storage tank (AST) site in Michigan is being conducted through in-situ and ex-situ closed-loop soil vapor extraction (SVE), soil vapor treatment, and treated air injection (AI) processes. The soil vapor extraction process applies a vacuum through the petroleum hydrocarbon affected soils in the ex-situ bio-remediation pile (bio-pile) and along the perimeter of excavated area (in-situ area) to remove the volatile or light petroleum hydrocarbons. This process also draws ambient air into the ex-situ bio-pile and in-situ vadose zone soil along the perimeter of excavated area to enhance biodegradation of light and heavy petroleum hydrocarbons in the soil. The extracted soil vapor is treated using a custom-designed air bio-remediation filter (bio-filter) to degrade the petroleum hydrocarbon compounds in the soil vapor extraction air streams. The treated air is then injected into a flush grade soil bed in the backfill area to perform final polishing of the air stream, and to form a closed-loop air flow with the soil vapor extraction perforated pipes along the perimeter of the excavated area

  8. Detection of Bacillus anthracis in the air, soil and animal tissue

    OpenAIRE

    Kušar D.; Pate M.; Hubad B.; Avberšek J.; Logar K.; Lapanje A.; Zrimec A.; Ocepek M.

    2012-01-01

    The objective of the present work was to establish effective and rapid diagnostic methods for the detection of Bacillus anthracis, a highly virulent zoonotic pathogen, in the air, soil and animal (or human) tissue samples. Liquid culture of B. anthracis was aerosolized and four air sampling procedures were employed. Detection of B. anthracis in the air samples was successful with RCS High Flow sampler (culturebased detection) and when sampling through the a...

  9. Elaboration of amniotic membrane dressing dried by air and irradiated - Peruvian experience

    International Nuclear Information System (INIS)

    The purpose of this work is to prepare dressings from the amniotic membrane to be used in cases of skin damage principally due to superficial and intermediate second-degree burns. The amnion is a transparent membrane that lines the chorion. It is resistant and rich in collagen. Due to these characteristics it can be well used as biological dressing as it diminishes the loss of fluids, electrolytes and proteins, it also protects the growing epithelium and adheres well to the surface of the wound, improves mobility of the patient, diminishing pain and stimulating neovascularization. The ISN-IPEN Tissue Bank promoted by IAEA has processed amniotic membrane since July 1997. Initially dressings were prepared using antibiotics, after IAEA training at the MINT of Malaysia, it is processed dried by air, lyophylized and in both presentations, sterilized by gamma-rays. Amniotic membranes are procured from Lima Maternity. Tissues must comply with VDRL, HIV, Hepatitis B and C exclusion tests. The process is held in a laminar flow hood and amnion already separated from the chorion is washed with sterile distilled water, a solution of 0.05% sodium hypochlorite, and normal saline. Then it is cut into appropriate sizes and double packed in PE films. The dressings are then carried to the Peruvian Institute of Nuclear Energy for irradiation, depending on the number of samples either irradiated with gamma-rays at the Gammacell 220 or at the Irradiation Facility located in Santa Anita. The delivered dose is 25 kGy. The product is only released if it complies with the end product quality controls. Meanwhile, microbiological tests are carried out during all the processing stages, in order to monitor the microbial load during production. In conclusion we can state that dressings prepared as above mentioned have the following advantages: not complicated preparation; reliable and safe for clinical use; diminish infection rates and days spent in the hospital; easy to storage; and can be

  10. Decadal co-variability of the summer surface air temperature and soil moisture in China under global warming

    Institute of Scientific and Technical Information of China (English)

    SU MingFeng; WANG HuiJun

    2007-01-01

    The self-calibrating Palmer Drought Severity Index (PDSI) is calculated using newly updated ground observations of monthly surface air temperature (SAT) and precipitation in China. The co-variabilities of PDSI and SAT are examined for summer for the period 1961-2004. The results show that there exist decadal climate co-variabilities and strong nonlinear interactions between SAT and soil moisture in many regions of China. Some of the co-variabilities can be linked to global warming. In summer, significant decadal co-variabilities from cool-wet to warm-dry conditions are found in the east region of Northwest China, North China, and Northeast China. An important finding is that in the west region of Northwest China and Southeast China, pronounced decadal co-variabilities take place from warm-dry to cool-wet conditions. Because significant warming was observed over most areas of the global land surface during the past 20-30 years, the shift to cool-wet conditions is a unique phenomenon which may deserve much scientific attention. The nonlinear interactions between SAT and soil moisture may partly account for the observed decadal co-variabilities. It is shown that anomalies of SAT will greatly affect the climatic co-variabilities, and changes of SAT may bring notable influence on the PDSI in China. These results provide observational evidence for increasing risks of decadal drought and wetness as anthropogenic global warming progresses.

  11. Influence of drying by convective air dryer or power ultrasound on the vitamin C and β-carotene content of carrots.

    Science.gov (United States)

    Frias, Juana; Peñas, Elena; Ullate, Mónica; Vidal-Valverde, Concepción

    2010-10-13

    Convective air drying and power ultrasound effects on vitamin C and β-carotene contents in carrots were studied. For convective air drying, a central composite face-centered design fitting temperature between 40 and 65 °C and air flow rate between 2 and 6 × 10(-1) m/s were used; previously, carrots were blanched. Likewise, ultrasound drying was performed on both unblanched and blanched carrots at 20, 40, and 60 °C for 120, 90, and 75 min, respectively. Blanching had a sharp effect on vitamin C and β-carotene degradation (80-92% retentions, respectively), and convective air drying led to further losses (32-50% and 73-90% retentions, respectively). According to the response surface model, a combination of 40 °C and 6 × 10(-1) m/s will maximize vitamin C retention in dried carrots, whereas 40 °C and 3.3 × 10(-1) m/s will ensure the highest β-carotene content. Ultrasound drying caused higher vitamin C and β-carotene retention (82-92% and 96-98%, respectively) than convective air drying. Blanched carrots dehydrated by ultrasound showed retentions of 55% and 88% of vitamin C and β-carotene, respectively. Ultrasound drying at 20 °C for 120 min caused the maximum vitamin C and β-carotene contents. Therefore, power ultrasound may be considered a valuable tool to obtain high nutritive dehydrated carrots. PMID:20843024

  12. Spectra and vegetation index variations in moss soil crust in different seasons, and in wet and dry conditions

    Science.gov (United States)

    Fang, Shibo; Yu, Weiguo; Qi, Yue

    2015-06-01

    Similar to vascular plants, non-vascular plant mosses have different periods of seasonal growth. There has been little research on the spectral variations of moss soil crust (MSC) over different growth periods. Few studies have paid attention to the difference in spectral characteristics between wet MSC that is photosynthesizing and dry MSC in suspended metabolism. The dissimilarity of MSC spectra in wet and dry conditions during different seasons needs further investigation. In this study, the spectral reflectance of wet MSC, dry MSC and the dominant vascular plant (Artemisia) were characterized in situ during the summer (July) and autumn (September). The variations in the normalized difference vegetation index (NDVI), biological soil crust index (BSCI) and CI (crust index) in different seasons and under different soil moisture conditions were also analyzed. It was found that (1) the spectral characteristics of both wet and dry MSCs varied seasonally; (2) the spectral features of wet MSC appear similar to those of the vascular plant, Artemisia, whether in summer or autumn; (3) both in summer and in autumn, much higher NDVI values were acquired for wet than for dry MSC (0.6 ∼ 0.7 vs. 0.3 ∼ 0.4 units), which may lead to misinterpretation of vegetation dynamics in the presence of MSC and with the variations in rainfall occurring in arid and semi-arid zones; and (4) the BSCI and CI values of wet MSC were close to that of Artemisia in both summer and autumn, indicating that BSCI and CI could barely differentiate between the wet MSC and Artemisia.

  13. Air-soil exchange of organochlorine pesticides in a sealed chamber.

    Science.gov (United States)

    Yang, Bing; Han, Baolu; Xue, Nandong; Zhou, Lingli; Li, Fasheng

    2015-01-01

    So far little is known about air-soil exchange under any sealed circumstances (e.g., in plastic and glass sheds), which however has huge implications for the soil-air-plant pathways of persistent organic pollutants including organochlorine pesticides (OCPs). A newly designed passive air sampler was tested in a sealed chamber for measuring the vertical concentration profiles of gaseous phase OCPs (hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs)). Air was sampled at 5, 15, and 30 cm above ground level every 10th day during a 60-day period by deploying polyurethane foam cylinders housed in acrylonitrile butadiene styrene-covered cartridges. Concentrations and compositions of OCPs along the vertical sections indicated a clear relationship with proximity to the mixture of HCHs and DDTs which escapes from the soils. In addition, significant positive correlations were found between air temperatures and concentrations of HCHs and DDTs. These results indicated revolatilization and re-deposition being at or close to dynamic pseudo-equilibrium with the overlying air. The sampler used for addressing air-soil exchange of persistent organic pollutants in any sealed conditions is discussed. PMID:25597683

  14. Air-soil exchange of organochlorine pesticides in a sealed chamber

    Institute of Scientific and Technical Information of China (English)

    Bing Yang; Baolu Han; Nandong Xue; Lingli Zhou; Fasheng Li

    2015-01-01

    So far little is known about air-soil exchange under any sealed circumstances (e.g.,in plastic and glass sheds),which however has huge implications for the soil-air-plant pathways of persistent organic pollutants including organochlorine pesticides (OCPs).A newly designed passive air sampler was tested in a sealed chamber for measuring the vertical concentration profiles of gaseous phase OCPs (hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs)).Air was sampled at 5,15,and 30 cm above ground level every 10th day during a 60-day period by deploying polyurethane foam cyhnders housed in acrylonitrile butadiene styrene-covered cartridges.Concentrations and compositions of OCPs along the vertical sections indicated a clear relationship with proximity to the mixture of HCHs and DDTs which escapes from the soils.In addition,significant positive correlations were found between air temperatures and concentrations of HCHs and DDTs.These results indicated revolatilization and re-deposition being at or close to dynamic pseudo-equilibrium with the overlying air.The sampler used for addressing air-soil exchange of persistent organic pollutants in any sealed conditions is discussed.

  15. Variations in soil carbon sequestration and their determinants along a precipitation gradient in seasonally dry tropical forest ecosystems.

    Science.gov (United States)

    Campo, Julio; Merino, Agustín

    2016-05-01

    The effect of precipitation regime on the C cycle of tropical forests is poorly understood, despite the existence of models that suggest a drier climate may substantially alter the source-sink function of these ecosystems. Along a precipitation regime gradient containing 12 mature seasonally dry tropical forests growing under otherwise similar conditions (similar annual temperature, rainfall seasonality, and geological substrate), we analyzed the influence of variation in annual precipitation (1240 to 642 mm) and duration of seasonal drought on soil C. We investigated litterfall, decomposition in the forest floor, and C storage in the mineral soil, and analyzed the dependence of these processes and pools on precipitation. Litterfall decreased slightly - about 10% - from stands with 1240 mm yr(-1) to those with 642 mm yr(-1) , while the decomposition decreased by 56%. Reduced precipitation strongly affected C storage and basal respiration in the mineral soil. Higher soil C storage at the drier sites was also related to the higher chemical recalcitrance of litter (fine roots and forest floor) and the presence of charcoal across sites, suggesting an important indirect influence of climate on C sequestration. Basal respiration was controlled by the amount of recalcitrant organic matter in the mineral soil. We conclude that in these forest ecosystems, the long-term consequences of decreased precipitation would be an increase in organic layer and mineral soil C storage, mainly due to lower decomposition and higher chemical recalcitrance of organic matter, resulting from changes in litter composition and, likely also, wildfire patterns. This could turn these seasonally dry tropical forests into significant soil C sinks under the predicted longer drought periods if primary productivity is maintained. PMID:26913708

  16. Air-drying paint compositions comprising carbohydrate-based polyesters and polyester preparation

    OpenAIRE

    Oostveen, E.A.; Weijnen, J.; Haveren, van, J.; Gillard, M.

    2003-01-01

    The invention relates to a polyester obtainable by transesterification or interesterification of:(i) a carbohydrate or an acyl ester thereof, (ii) an alkyl ester of a drying fatty acid, semi-drying fatty acid or mixture thereof; and (iii) an alkyl ester of a non aromatic polycarboxylic acid. The invention further relates to a method for the preparation of a polyester comprising the step of transesterification or interesterification.

  17. Intranasal cold dry air is superior to histamine challenge in determining the presence and degree of nasal hyperreactivity in nonallergic noninfectious perennial rhinitis

    NARCIS (Netherlands)

    J.P. Braat (Joseph); W.J. Fokkens (Wytske); R. Gerth van Wijk (Roy); E. Rijntjes; P.G.H. Mulder (Paul)

    1998-01-01

    textabstractThe objective of the study was to compare cold dry air (CDA) and histamine in differentiating patients with nonallergic noninfectious perennial rhinitis (NANIPER) from control subjects. Nasal reactivity (nasal patency, mucus production, and sneezing) in 16 s

  18. Uptake of polychlorinated biphenyls and organochlorine pesticides from soil and air into radishes (Raphanus sativus)

    Energy Technology Data Exchange (ETDEWEB)

    Mikes, Ondrej; Cupr, Pavel [RECETOX, Research Centre for Environmental Chemistry and Ecotoxicology, Masaryk University, Kamenice 126/3, 625 00 Brno (Czech Republic); Trapp, Stefan [Department of Environmental Engineering, Technical University of Denmark, Miljoevej 113, DK-2800 Kgs. Lyngby (Denmark); Klanova, Jana [RECETOX, Research Centre for Environmental Chemistry and Ecotoxicology, Masaryk University, Kamenice 126/3, 625 00 Brno (Czech Republic)], E-mail: klanova@recetox.muni.cz

    2009-02-15

    Uptake of organochlorine pesticides and polychlorinated biphenyls from soil and air into radishes was measured at a heavily contaminated field site. The highest contaminant concentrations were found for DDT and its metabolites, and for {beta}-hexachlorocyclohexane. Bioconcentration factor (BCF, defined as a ratio between the contaminant concentration in the plant tissue and concentration in soil) was determined for roots, edible bulbs and shoots. Root BCF values were constant and not correlated to log K{sub OW}. A negative correlation between BCF and log K{sub OW} was found for edible bulbs. Shoot BCF values were rather constant and varied between 0.01 and 0.22. Resuspended soil particles may facilitate the transport of chemicals from soil to shoots. Elevated POP concentrations found in shoots of radishes grown in the control plot support the hypothesis that the uptake from air was more significant for shoots than the one from soil. The uptake of POPs from air was within the range of theoretical values predicted from log K{sub OA}. - Uptake from air represented for majority of persistent organochlorines a dominant pathway into shoots while uptake from soil was dominant for roots.

  19. Uptake of polychlorinated biphenyls and organochlorine pesticides from soil and air into radishes (Raphanus sativus)

    International Nuclear Information System (INIS)

    Uptake of organochlorine pesticides and polychlorinated biphenyls from soil and air into radishes was measured at a heavily contaminated field site. The highest contaminant concentrations were found for DDT and its metabolites, and for β-hexachlorocyclohexane. Bioconcentration factor (BCF, defined as a ratio between the contaminant concentration in the plant tissue and concentration in soil) was determined for roots, edible bulbs and shoots. Root BCF values were constant and not correlated to log KOW. A negative correlation between BCF and log KOW was found for edible bulbs. Shoot BCF values were rather constant and varied between 0.01 and 0.22. Resuspended soil particles may facilitate the transport of chemicals from soil to shoots. Elevated POP concentrations found in shoots of radishes grown in the control plot support the hypothesis that the uptake from air was more significant for shoots than the one from soil. The uptake of POPs from air was within the range of theoretical values predicted from log KOA. - Uptake from air represented for majority of persistent organochlorines a dominant pathway into shoots while uptake from soil was dominant for roots

  20. Response of four foliage plants to heated soil and reduced air temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bodnaruk, W.H. Jr.; Mills, T.W.; Ingram, D.L.

    1981-01-01

    Tip cuttings of Dieffenbachia maculata (Lodd.) G. Donn Exotic Perfection Compacta' and Aglaonema commutatum Schott Silver Queen and single eye cuttings of Epipremnum aureum (Linden and Andre) Bunt, and Philodendron scandens oxycardium (Schott) Bunt. were propagated in combinations of 4 minimum air temperatures, 45/sup 0/, 50/sup 0/, 55/sup 0/ and 60/sup 0/F (7.2/sup 0/, 10/sup 0/, 12.7/sup 0/, 15.5/sup 0/C), and 2 soil temperature treatments; controlled 70/sup 0/F (21/sup 0/C) minimum and variable. Maintaining minimum soil temperatures at 70/sup 0/F reduced production times for rooted Dieffenbachia and Aglaonema tips by 45% and of Epipremnum and Philodendron suitable for 3 inch pots by 35% and 25%, respectively, regardless of minimum air temperature. Minimum air temperature had little effect on Dieffenbachia or Aglaonema root number and length at 70/sup 0/F soil temperature. Similarly shoot length and number of leaves of Philodendron and Epipremnum were not affected by minimum air temperatures with 70/sup 0/F soil temperature. Plant quality was uniformly high in all crops at the 70/sup 0/F soil minimum for all air temperatures except Epipremnum which was chlorotic at 45/sup 0/F. A description of a warm water in-benching heating system is included. 6 references, 2 figures, 9 tables.

  1. Improved Formulations for Air-Surface Exchanges Related to National Security Needs: Dry Deposition Models

    Energy Technology Data Exchange (ETDEWEB)

    Droppo, James G.

    2006-07-01

    The Department of Homeland Security and others rely on results from atmospheric dispersion models for threat evaluation, event management, and post-event analyses. The ability to simulate dry deposition rates is a crucial part of our emergency preparedness capabilities. Deposited materials pose potential hazards from radioactive shine, inhalation, and ingestion pathways. A reliable characterization of these potential exposures is critical for management and mitigation of these hazards. A review of the current status of dry deposition formulations used in these atmospheric dispersion models was conducted. The formulations for dry deposition of particulate materials from am event such as a radiological attack involving a Radiological Detonation Device (RDD) is considered. The results of this effort are applicable to current emergency preparedness capabilities such as are deployed in the Interagency Modeling and Atmospheric Assessment Center (IMAAC), other similar national/regional emergency response systems, and standalone emergency response models. The review concludes that dry deposition formulations need to consider the full range of particle sizes including: 1) the accumulation mode range (0.1 to 1 micron diameter) and its minimum in deposition velocity, 2) smaller particles (less than .01 micron diameter) deposited mainly by molecular diffusion, 3) 10 to 50 micron diameter particles deposited mainly by impaction and gravitational settling, and 4) larger particles (greater than 100 micron diameter) deposited mainly by gravitational settling. The effects of the local turbulence intensity, particle characteristics, and surface element properties must also be addressed in the formulations. Specific areas for improvements in the dry deposition formulations are 1) capability of simulating near-field dry deposition patterns, 2) capability of addressing the full range of potential particle properties, 3) incorporation of particle surface retention/rebound processes, and

  2. THE INFLUENCE OF AIR-DRYING ON HYPER-REMINERALIZATION OF DEMINERALIZED DENTIN - A STUDY ON BULK AS WELL AS ON THIN WET SECTION OF BOVINE DENTIN

    NARCIS (Netherlands)

    INABA, D; IIJIMA, Y; TAKAGI, O; RUBEN, J; ARENDS, J

    1995-01-01

    The influence of air-drying on the remineralization of demineralized bovine dentine was examined in wet bulk samples, in dried bulk samples as well as in wet thin sections. Bulk samples of bovine dentine were first demineralized in an acidic gel (pH = 5) at 37 degrees C for 3 weeks. After 24-hour pr

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

    Science.gov (United States)

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

    2012-05-01

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

  4. Performance Evaluation of a Solar Dryer with Finny, Perforated Absorber Plate Collector Equipped with an Air Temperature Control System for Dill Drying

    Directory of Open Access Journals (Sweden)

    M Razmipour

    2016-04-01

    Full Text Available Dill is one of the most important plants in the world because of its medicinal properties and it is widely used as a vegetable in the most parts of Iran. In the present study a new solar dryer with finny, perforated absorber plate collector was utilized to dry fresh dill. The dryer was comprised of a solar collector, a product container, a fan and a drying air temperature controller. The temperature controller was used as a control system to regulate the drying air temperature. Thermal performance of the dryer with finny, perforated solar collector was compared with that of a simple flat plate solar collector at different airflow rates. The effect of drying air temperature at three levels (45, 55 and 65 °C, the product size at three lengths (3, 5 and 7 cm and two different modes of drying (mixed and indirect on the dryer performance was investigated. The results showed that the finny, perforated absorber plate solar collector could improve the thermal efficiency about 11% in comparison with the flat plate collector and the highest thermal efficiency was achieved at the maximum airflow rate. Meanwhile, increasing the air temperature and decreasing the product size caused a significant reduction in energy consumption. Solar fraction reduced by increasing the air temperature. Finally a maximum dryer efficiency of 70% was observed at air temperature of 65 oC, product size of 3 cm with mixed mode drying.

  5. High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air

    OpenAIRE

    Rella, C. W.; H Chen; A. E. Andrews; A. Filges; C. Gerbig; Hatakka, J.; A. Karion; N. L. Miles; Richardson, S. J.; M. Steinbacher; C. Sweeney; Wastine, B.; Zellweger, C.

    2012-01-01

    Traditional techniques for measuring the mole fractions of greenhouse gas in the well-mixed atmosphere have required extremely dry sample gas streams (dew point < −25 °C) to achieve the inter-laboratory compatibility goals set forth by the Global Atmospheric Watch program of the World Meteorological Organization (WMO/GAW) for carbon dioxide (±0.1 ppm) and methane (±2 ppb). Drying the sample gas to low levels of water vapor can be expensive, time-consuming, and/or problematic, especial...

  6. Effects of Land Use Change and Seasonality of Precipitation on Soil Nitrogen in a Dry Tropical Forest Area in the Western Llanos of Venezuela

    OpenAIRE

    2014-01-01

    We evaluated changes of different soil nitrogen forms (total N, available ammonium and nitrate, total N in microbial biomass, and soil N mineralization) after conversion of semideciduous dry tropical forest in 5- and 18-year-old pastures (YP and OP, resp.) in the western Llanos of Venezuela. This evaluation was made at early rainy season, at end rainy season, and during dry season. With few exceptions, no significant differences were detected in the total N in the three study sites. Compared ...

  7. Retention of Structure and Function of the Cat Germinal Vesicle after Air-Drying and Storage at Suprazero Temperature1

    OpenAIRE

    Graves-Herring, Jennifer E.; Wildt, David E.; Comizzoli, Pierre

    2013-01-01

    The study explored a novel approach for preserving the maternal genome without the entire oocyte by air-drying the cat germinal vesicle (GV) in the presence of the disaccharide trehalose. Specifically, we examined GV structure and function after desiccation, storage at 4°C (up to 32 wk), and rehydration including the ability to resume meiosis after injection into a fresh, conspecific cytoplast. In experiment 1, DNA integrity was similar to fresh controls after 1 and 4 wk storage in the presen...

  8. Dry/wet performance of a plate-fin air-cooled heat exchanger with continuous corrugated fins

    International Nuclear Information System (INIS)

    The performance and operating characteristics of a plate-fin heat exchanger in dry/wet or deluge operations was experimentally determined. Development of the deluge heat/mass transfer model continued. The experiments were conducted in a specially-designed wind tunnel at the PNL. Air that was first heated and humidified to specified conditions was circulated at a controlled rate through a 2 ft x 6 ft heat exchanger module. The heat exchanger used in the tests was a wavy surface, plate fin on tube configuration. Hot water was circulated through the tubes at high flow rates to maintain an essentially isothermal condition on the tube side. Deionized water sprayed on the top of the vertically oriented plate fins was collected at the bottom of the core and recirculated. Instrumentation was provided for measurement of flow rates and thermodynamic conditions in the air, in the core circulation water, and in the deluge water. Measurements of the air side pressure drop and heat rejection rate were made as a function of air flow rate, air inlet temperature and humidity, deluge water flow rate, and the core inclination from the vertical. An overall heat transfer coefficient and an effective deluge film convective coefficient was determined. The deluge model, for predicting heat transfer from a wet finned heat exchanger was further developed and refined, and a major extension of the model was formulated that permits simultaneous calculation of both the heat transfer and evaporation rates from the wetted surface. The experiments showed an increase in the heat rejection rate due to wetting, accompanied by a proportional increase in the air side pressure drop. For operation at the same air side pressure drop, the enhancement ratio Q/sub w//Q/sub d/ varied between 2 and 5 for the conditions tested. Thus, the potential enhancement of heat transfer due to wetting can be substantial

  9. Dry/wet performance of a plate-fin air-cooled heat exchanger with continuous corrugated fins

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, S.G.; Kreid, D.K.; Johnson, B.M.

    1981-01-01

    The performance and operating characteristics of a plate-fin heat exchanger in dry/wet or deluge operations was experimentally determined. Development of the deluge heat/mass transfer model continued. The experiments were conducted in a specially-designed wind tunnel at the PNL. Air that was first heated and humidified to specified conditions was circulated at a controlled rate through a 2 ft x 6 ft heat exchanger module. The heat exchanger used in the tests was a wavy surface, plate fin on tube configuration. Hot water was circulated through the tubes at high flow rates to maintain an essentially isothermal condition on the tube side. Deionized water sprayed on the top of the vertically oriented plate fins was collected at the bottom of the core and recirculated. Instrumentation was provided for measurement of flow rates and thermodynamic conditions in the air, in the core circulation water, and in the deluge water. Measurements of the air side pressure drop and heat rejection rate were made as a function of air flow rate, air inlet temperature and humidity, deluge water flow rate, and the core inclination from the vertical. An overall heat transfer coefficient and an effective deluge film convective coefficient was determined. The deluge model, for predicting heat transfer from a wet finned heat exchanger was further developed and refined, and a major extension of the model was formulated that permits simultaneous calculation of both the heat transfer and evaporation rates from the wetted surface. The experiments showed an increase in the heat rejection rate due to wetting, accompanied by a proportional increase in the air side pressure drop. For operation at the same air side pressure drop, the enhancement ratio Q/sub w//Q/sub d/ varied between 2 and 5 for the conditions tested. Thus, the potential enhancement of heat transfer due to wetting can be substantial.

  10. Utilization of air pollution control residues for the stabilization/solidification of trace element contaminated soil.

    Science.gov (United States)

    Travar, I; Kihl, A; Kumpiene, J

    2015-12-01

    The aim of this study was to evaluate the stabilization/solidification (S/S) of trace element-contaminated soil using air pollution control residues (APCRs) prior to disposal in landfill sites. Two soil samples (with low and moderate concentrations of organic matter) were stabilized using three APCRs that originated from the incineration of municipal solid waste, bio-fuels and a mixture of coal and crushed olive kernels. Two APCR/soil mixtures were tested: 30% APCR/70% soil and 50% APCR/50% soil. A batch leaching test was used to study immobilization of As and co-occurring metals Cr, Cu, Pb and Zn. Solidification was evaluated by measuring the unconfined compression strength (UCS). Leaching of As was reduced by 39-93% in APCR/soil mixtures and decreased with increased amounts of added APCR. Immobilization of As positively correlated with the amount of Ca in the APCR and negatively with the amount of soil organic matter. According to geochemical modelling, the precipitation of calcium arsenate (Ca3(AsO4)2/4H2O) and incorporation of As in ettringite (Ca6Al2(SO4)3(OH)12 · 26H2O) in soil/APCR mixtures might explain the reduced leaching of As. A negative effect of the treatment was an increased leaching of Cu, Cr and dissolved organic carbon. Solidification of APCR/soil was considerably weakened by soil organic matter. PMID:26233740

  11. High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air

    Directory of Open Access Journals (Sweden)

    C. W. Rella

    2013-03-01

    Full Text Available Traditional techniques for measuring the mole fractions of greenhouse gases in the well-mixed atmosphere have required dry sample gas streams (dew point inter-laboratory compatibility goals (WMO, 2011a without drying the sample gas. In this paper, we present laboratory methodology for empirically deriving the water vapour correction factors, and we summarise a series of in-situ validation experiments comparing the measurements in humid gas streams to well-characterised dry-gas measurements. By using the manufacturer-supplied correction factors, the dry-mole fraction measurements have been demonstrated to be well within the GAW compatibility goals up to a water vapour concentration of at least 1%. By determining the correction factors for individual instruments once at the start of life, this water vapour concentration range can be extended to at least 2% over the life of the instrument, and if the correction factors are determined periodically over time, the evidence suggests that this range can be extended up to and even above 4% water vapour concentrations.

  12. The Influence of Sample Drying Procedures on Mercury Concentrations Analyzed in Soils

    Czech Academy of Sciences Publication Activity Database

    Hojdová, Maria; Rohovec, Jan; Chrastný, V.; Penížek, V.; Navrátil, Tomáš

    2015-01-01

    Roč. 94, č. 5 (2015), s. 570-576. ISSN 0007-4861 R&D Projects: GA ČR GP526/09/P404; GA ČR(CZ) GAP210/11/1369 Institutional support: RVO:67985831 Keywords : sample preparation * drying procedures * microbial activity * freeze - drying * contamination Subject RIV: DD - Geochemistry Impact factor: 1.255, year: 2014

  13. Adaptive transgenerational plasticity in an annual plant: grandparental and parental drought stress enhance performance of seedlings in dry soil.

    Science.gov (United States)

    Herman, Jacob J; Sultan, Sonia E; Horgan-Kobelski, Tim; Riggs, Charlotte

    2012-07-01

    Stressful parental (usually maternal) environments can dramatically influence expression of traits in offspring, in some cases resulting in phenotypes that are adaptive to the inducing stress. The ecological and evolutionary impact of such transgenerational plasticity depends on both its persistence across generations and its adaptive value. Few studies have examined both aspects of transgenerational plasticity within a given system. Here we report the results of a growth-chamber study of adaptive transgenerational plasticity across two generations, using the widespread annual plant Polygonum persicaria as a naturally evolved model system. We grew five inbred Polygonum genetic lines in controlled dry vs. moist soil environments for two generations in a fully factorial design, producing replicate individuals of each genetic line with all permutations of grandparental and parental environment. We then measured the effects of these two-generational stress histories on traits critical for functioning in dry soil, in a third (grandchild) generation of seedling offspring raised in the dry treatment. Both grandparental and parental moisture environment significantly influenced seedling development: seedlings of drought-stressed grandparents or parents produced longer root systems that extended deeper and faster into dry soil compared with seedlings of the same genetic lines whose grandparents and/or parents had been amply watered. Offspring of stressed individuals also grew to a greater biomass than offspring of nonstressed parents and grandparents. Importantly, the effects of drought were cumulative over the course of two generations: when both grandparents and parents were drought-stressed, offspring had the greatest provisioning, germinated earliest, and developed into the largest seedlings with the most extensive root systems. Along with these functionally appropriate developmental effects, seedlings produced after two previous drought-stressed generations had

  14. High accuracy measurements of dry mole fractions of carbon dioxide and methane in humid air

    Directory of Open Access Journals (Sweden)

    C. W. Rella

    2012-08-01

    Full Text Available Traditional techniques for measuring the mole fractions of greenhouse gas in the well-mixed atmosphere have required extremely dry sample gas streams (dew point < −25 °C to achieve the inter-laboratory compatibility goals set forth by the Global Atmospheric Watch program of the World Meteorological Organization (WMO/GAW for carbon dioxide (±0.1 ppm and methane (±2 ppb. Drying the sample gas to low levels of water vapor can be expensive, time-consuming, and/or problematic, especially at remote sites where access is difficult. Recent advances in optical measurement techniques, in particular Cavity Ring Down Spectroscopy (CRDS, have led to the development of highly stable and precise greenhouse gas analyzers capable of highly accurate measurements of carbon dioxide, methane, and water vapor. Unlike many older technologies, which can suffer from significant uncorrected interference from water vapor, these instruments permit for the first time accurate and precise greenhouse gas measurements that can meet the WMO/GAW inter-laboratory compatibility goals without drying the sample gas. In this paper, we present laboratory methodology for empirically deriving the water vapor correction factors, and we summarize a series of in-situ validation experiments comparing the measurements in humid gas streams to well-characterized dry-gas measurements. By using the manufacturer-supplied correction factors, the dry-mole fraction measurements have been demonstrated to be well within the GAW compatibility goals up to at least 1% water vapor. By determining the correction factors for individual instruments once at the start of life, this range can be extended to at least 2% over the life of the instrument, and if the correction factors are determined periodically over time, the evidence suggests that this range can be extended above 4%.

  15. Simultaneous decay of contact-angle and surface-tension during the rehydration of air-dried root mucilage

    Science.gov (United States)

    Arye, Gilboa; Chen, Fengxian

    2016-04-01

    Plants can extract or exude water and solutes at their root surface. Among the root exudates, the mucilage exhibits a surfactant like properties - depressing the surface-tension (ST, mN/m) at the water-air interface. The amphipathic nature of some of the mucilage molecules (e.g. lipids) is thought to be the reason for its surfactant like behavior. As the rhizosphere dries out, re-orientation and/or re-configuration of amphipathic molecules at the solid-air interface, may impart hydrophobic nature to the rhizosphere. Our current knowledge on the ST of natural and/or model root mucilage is based on measurements of the equilibrium ST. However, adsorption of amphipathic molecules at the water-air interface is not reached instantaneously. The hydrophobic nature of the rhizosphere was deduced from the initial advancing CA, commonly calculated from the first few milliseconds up to few seconds (depending on the method employed). We hypothesized that during the rehydration of the root mucilage; both quantities are dynamic. Processes such as water absorbance and dissolution, may vary the interfacial tensions as a function of time. Consequently, simultaneous reduction of both CA and ST as a function of time can be expected. The main objective of this study was to characterize and quantify the extent, persistency and dynamic of the CA and ST during rehydration of air-dried root mucilage. The study was involved with measurements of dynamic and equilibrium ST using the pedant drop or Wilhelmy plate method, respectively. Glass slides were coated with naturally occurring or model root mucilage and the CA of a sessile drop was measured optically, as a function of time. The results were analyzed based on the Young-Dupré and Young-Laplace equations, from which the simultaneous decay of CA and ST was deduced. The implication for the wettability and water flow in the rhizosphere will be discussed.

  16. Micro-PIXE investigations of apoplastic iron in freeze-dried root cross-sections of soil grown barley

    International Nuclear Information System (INIS)

    Freeze-dried cryo-sections of barley roots (Hordeum vulgare L. cv. Alexis) were used to investigate the possible role of the root apoplast as an iron-storage pool for plants; this possibility has been a matter of controversy. Micro-PIXE analyzes in pixel mode were complemented by the STIM technique. Data were analyzed using the new Heidelberg software package BIOPIXE, which provides true elemental maps of inhomogeneous samples such as freeze-dried cross-sections of roots. The maps clearly show a high heterogeneity of the iron distribution in roots between adjacent cell layers. Accumulations of iron were observed in the cell walls of the outermost cell layers of the roots and at the endodermis. Based on the correlation between iron and soil related elements like titanium, aluminum and silicon, most of the iron located at the root surface could be attributed to soil contamination. It could also be shown that these soil contaminations lead to an overestimation of the apoplastic iron concentrations determined by methods commonly used in the botanical field. Besides this, low accumulations of iron were observed in the cell walls of the outmost cell layers of the roots. This may indicate that the root apoplast may have a minor function in iron nutrition

  17. Atmospheric inorganic nitrogen in dry deposition to a typical red soil agro-ecosystem in southeastern China.

    Science.gov (United States)

    Cui, Jian; Zhou, Jing; Yang, Hao

    2010-06-01

    Atmospheric dry deposition is an important pathway of nitrogen (N) sources input to agro-ecosystems. With the knowledge of increasing agricultural effects by dry N deposition, researchers have paid great attention to this topic. Characteristics of dry N deposition were estimated by a big-leaf resistance analogy model and the Auto-Meteorological Experiment Station (AMES) in a typical red soil agro-ecosystem in southeastern China for two years (2005-2006). Monthly dry deposition velocities (V(d)) were in the range of 0.16-0.36, 0.07-0.17 and 0.07-0.24 cm s(-1) for NH(3), NO(2) and aerosol particles (aerosol NH(4)(+) or NO(3)(-)), respectively, and the V(d) were higher in spring and winter than in summer and autumn. Monthly dry N deposition concentration (C(a)) and inferred deposition flux (F(d)) were in the range of 63.38-261.10, 47.21-278.92, 1.56-7.15, 47.21-278.92 microg N m(-3) and of 1.31-8.60, 0.38-3.67, 0-0.08, 0.01-0.23 kg N ha(-2) for NH(3), NO(2), aerosol NH(4)(+) and aerosol NO(3)(-), respectively. During the study period (2005-2006), the total dry N deposition was 70.55 kg N ha(-1) yr(-1) which equivalent to 1.53.8 kg (urea) ha(-1) yr(-1) or 415.0 kg (ammonium bicarbonate) ha(-1) yr(-1) applied in the red soil agro-ecosystems. In addition, the annual mean N depositions, mean sum of the monthly N depositions were 69.44, 1.12, 53.95 and 16.60 kg N ha(-1) yr(-1) for gaseous N, aerosol N, ammonia N and oxidized N, making up 98.42%, 1.58%, 53.95% and 16.60% of the total dry deposition N (70.50 kg ha(-1) yr(-1)). PMID:20532381

  18. X-ray CT-Derived Soil Characteristics Explain Varying Air, Water, and Solute Transport Properties across a Loamy Field

    DEFF Research Database (Denmark)

    Paradelo Pérez, Marcos; Katuwal, Sheela; Møldrup, Per;

    2016-01-01

    The characterization of soil pore space geometry is important for explaining fluxes of air, water, and solutes through soil and understanding soil hydrogeochemical functions. X-ray computed tomography (CT) can be applied for this characterization, and in this study CT-derived parameters were used...... to explain water, air, and solute transport through soil. Forty-five soil columns (20 by 20 cm) were collected from an agricultural field in Estrup, Denmark, and subsequently scanned using a medical CT scanner. Nonreactive tracer leaching experiments were performed in the laboratory along with...... improved when the limiting macroporosity (the minimum macroporosity for every 0.6-mm layer along the soil column) was used, suggesting that soil layers with the narrowest macropore section restricted the flow through the whole soil column. Water, air, and solute transport were related with the CT...

  19. Air quality assessment in the periurban area of Mexico Megacity during dry hot season in 2011 and 2012

    Science.gov (United States)

    Garcia-Reynoso, Agustin; Santos Garcia-Yee, Jose; Barrera-Huertas, Hugo; Gerardo Ruiz-Suárez, Luis

    2016-04-01

    Air quality is a human health threat not only in urbanized areas, it also affects the surrounding zones. Interaction between urban and rural areas can be evaluated by measurements and using models for regional areas that includes in its domain the peri-urban regions. The use of monitoring sites in remote areas is useful however it is not possible to cover all the region the use of models can provide valuable information about the source and fate of the pollution and its transformation. In order to evaluate the influence of the Mexico Megacity in the air quality of the region, two field campaigns were performed during the dry hot season during 2011 and 2012. Meterological and pollutant measurements were made during February and march 2011, in three sites towards the south east of Mexico Megacity, and from march to April 2012 towards the west after the Popocatepetl-Iztaccihuatl mountain range. Air quality modeling were performed by using the National Emissions Inventory 2008 during the studied periods, a comparison between measurements and the air quality model was performed. This type of studies can offer information about the pollutant distribution, the meteorological conditions and the exactness of emissions inventories. The latest can be useful for emissions inventory developers and policy makers.

  20. Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wildfire

    Science.gov (United States)

    Sun, Q.; Meyer, W. S.; Koerber, G. R.; Marschner, P.

    2015-08-01

    Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wildfire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content, which could be further modulated by wildfire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy mallee woodland, where part of the woodland experienced a wildfire which destroyed or damaged most of the aboveground plant parts 4 months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80 % of maximum water holding capacity (WHC) for 19 days; in DRW, soils were dried for 4 days, kept dry for another 5 days, then rewetted to 80 % WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per gram of soil in CM and DRW was greater under trees, but lower when expressed per gram of total organic carbon (TOC). Organic matter content, available P, and microbial biomass C, but not available N, were greater under trees than in open areas. Wild fire decreased the flush of respiration per gram of TOC in the open areas and under shrubs, and reduced TOC and microbial biomass C (MBC) concentrations only under trees, but had little effect on available N and P concentrations. We conclude that the impact of wildfire and DRW events on nutrient cycling differs among vegetation patches of a native semi-arid woodland which is related to organic matter amount and availability.

  1. Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wild fire

    Science.gov (United States)

    Sun, Q.; Meyer, W. S.; Koerber, G.; Marschner, P.

    2015-06-01

    Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wild fire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well-known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content which could be further modulated by wild fire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy Mallee woodland, where part of the woodland experienced a wild fire which destroyed or damaged most of the aboveground plant parts four months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80% of maximum water holding capacity for 19 days; In DRW, soils were dried for four days, kept dry for another five days, then rewet to 80% WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per g soil in CM and DRW was greater under trees, but lower when expressed per g TOC. Organic matter content, available P, and microbial biomass C, but not available N were greater under trees than in open areas. Wild fire decreased the flush of respiration per g TOC in the open areas and under shrubs, and reduced TOC and MBC concentrations only under trees, but had little effect on available N and P concentrations. We conclude that of the impact wild fire and DRW events on nutrient cycling differ among vegetation patches of a native semiarid woodland which is related to organic matter amount and availability.

  2. Comparison, limitations and uncertainty of wet chemistry techniques, loss on ignition and dry combustion in soil organic carbon analysis

    Science.gov (United States)

    Ćirić, Vladimir; Manojlović, Maja; Belić, Milivoj; Nešić, Ljiljana; Švarc-Gajić, Jaroslava; Sitaula, Bishal K.

    2014-05-01

    Soil organic carbon (SOC) has an important role in natural processes (carbon cycle, global climate change and plant growth), agriculture, soil protection and biodiversity. Determination of SOC is usually based on the oxidation of soil organic matter (SOM). Many methods are available, each with advantages and disadvantages in terms of accuracy, costs, convenience and repeatability. Therefore, it is necessary to make a comprehensive overview in order to select appropriate method with the purpose of accurate SOC determination. Most errors in SOC stocks assessment and SOC monitoring occur due to differences in analytical approaches and procedures. This can be a key factor in making incorrect conclusions. The purpose of this research was to compare methods for SOC determination and highlight the strengths and weaknesses of individual methods. The research was conducted on soil samples collected from different soil types and different land uses of temperate region. The concentration of SOC in every sample was determined by the following methods: Tyrin's method, Tyrin's method without addition of AgSO4, Kotzmann's method, loss on ignition (LOI) method, Walkley-Black method, dry combustion by CHN analyzer with pretreatment with HCl and subtraction of volumetrically determined soil inorganic carbon (SIC) from dry combustion by CHN analyzer without pretreatment. Each of the applied methods demonstrated specific limitations. The average SOC concentration determined by different methods ranged from 16.1-28.5 g kg-1. It has been established that different methods for the determination of total SOC recovered 76-157% of SOC compared to the reference dry combustion method by CHN analyzer. The correlation coefficients between applied methods ranged from 0.74-0.98. The Tyrin's method without addition of AgSO4 can be recommended as the most suitable method for the determination of SOC, with mandatory use of the correction factor 1.14. For the purpose of reducing the difference

  3. Column Experiments Investigating Wetting and Drying of Soil and Consumption of Organic Contaminants for Managed Aquifer Recharge

    Science.gov (United States)

    Silver, M.; Schueth, C.; Wefer-Roehl, A.; Kuebeck, C.

    2014-12-01

    The EU FP7 project MARSOL seeks to address water scarcity challenges in arid regions. Within this framework, we conduct a series of experiments to evaluate the potential for water quality improvement and changes in hydraulic conductivity when managed aquifer recharge (MAR) is performed by infiltrating treated wastewater in soils that do not have high potential for sorption. For example, in the Attica (Athens and vicinity) region of Greece, the bedrock is mostly marble, resulting in calcite-rich soils that present little potential for sorption of contaminants to mineral surfaces. This leaves consumption of organic contaminants by microbes as the critical mechanism for water quality improvement, when treated wastewater is infiltrated through such soils. In order to enhance the potential for contaminant consumption by aerobic bacteria in a way that would be realistic to later perform in an infiltration basin, we conduct experiments using a series of wetting and drying cycles. The experimental setup consists of 90-cm long soil columns, fitted with oxygen sensors, time-domain reflectometry sensors (to measure moisture content), sampling ports, oxidation-reduction probes, and head observation tubes. We use the data collected from these sensors and features of the experimental setup to answer the following questions: 1. Does hydraulic conductivity change, from formation of a biofilm or dissolution of calcite (or both)? 2. Are organic contaminants consumed? 3. What effect do wetting and drying cycles have on consumption of organic contaminants? 4. How long can infiltration of treated wastewater last, before oxygen is consumed and conditions become reducing? These questions are investigated by observing the hydraulic head and outflow, performing tracer tests, taking samples from the sampling ports and outflow for chemical analyses, and measuring moisture content and oxygen concentration, in the course of performing multiple wetting and drying cycles. These column

  4. Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

    Energy Technology Data Exchange (ETDEWEB)

    Yehia, Ashraf [Department of Physics, Faculty of Science, Assiut University, Assiut 71516, Egypt and Department of Physics, College of Science and Humanitarian Studies in Alkharj, Salman bin Abdulaziz University, P.O. Box 83, Alkharj 11942 (Saudi Arabia); Mizuno, Akira [Department of Environmental and Life Sciences, Toyohashi University of Technology, Tempaku-cho, Toyohashi 441-8580 (Japan)

    2013-05-14

    An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

  5. Atmospheric absorption model for dry air and water vapor at microwave frequencies below 100 GHz derived from spaceborne radiometer observations

    Science.gov (United States)

    Wentz, Frank J.; Meissner, Thomas

    2016-05-01

    The Liebe and Rosenkranz atmospheric absorption models for dry air and water vapor below 100 GHz are refined based on an analysis of antenna temperature (TA) measurements taken by the Global Precipitation Measurement Microwave Imager (GMI) in the frequency range 10.7 to 89.0 GHz. The GMI TA measurements are compared to the TA predicted by a radiative transfer model (RTM), which incorporates both the atmospheric absorption model and a model for the emission and reflection from a rough-ocean surface. The inputs for the RTM are the geophysical retrievals of wind speed, columnar water vapor, and columnar cloud liquid water obtained from the satellite radiometer WindSat. The Liebe and Rosenkranz absorption models are adjusted to achieve consistency with the RTM. The vapor continuum is decreased by 3% to 10%, depending on vapor. To accomplish this, the foreign-broadening part is increased by 10%, and the self-broadening part is decreased by about 40% at the higher frequencies. In addition, the strength of the water vapor line is increased by 1%, and the shape of the line at low frequencies is modified. The dry air absorption is increased, with the increase being a maximum of 20% at the 89 GHz, the highest frequency considered here. The nonresonant oxygen absorption is increased by about 6%. In addition to the RTM comparisons, our results are supported by a comparison between columnar water vapor retrievals from 12 satellite microwave radiometers and GPS-retrieved water vapor values.

  6. Simultaneous Water Vapor and Dry Air Optical Path Length Measurements and Compensation with the Large Binocular Telescope Interferometer

    CERN Document Server

    Defrère, D; Downey, E; Böhm, M; Danchi, W C; Durney, O; Ertel, S; Hill, J M; Hoffmann, W F; Mennesson, B; Millan-Gabet, R; Montoya, M; Pott, J -U; Skemer, A; Spalding, E; Stone, J; Vaz, A

    2016-01-01

    The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 $\\mu$m). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illus...

  7. Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

    International Nuclear Information System (INIS)

    An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

  8. Estimation of air to grass - dry and wet deposition rates, velocities, and mass interception factors for iodine for a postulated accidental scenario

    International Nuclear Information System (INIS)

    Measurements of air to grass - dry and wet deposition rates, velocities, and mass interception factors for iodine are sparse in India. Data on these parameters are the basic input for the estimation of radiation dose to the public around a nuclear power plant. We have carried out systematic studies on air to grass - dry and wet deposition rates, velocities, and mass interception factors for iodine for a postulated emergency situation. The main objective of this study was to generate air to grass transfer factors for iodine for the environmental conditions prevailing in Kaiga

  9. Volumetric shrinkage characteristics of soil during drying%土体干燥过程中的体积收缩变形特征

    Institute of Scientific and Technical Information of China (English)

    唐朝生; 崔玉军; Anh-Minh Tang; 施斌

    2011-01-01

    通过开展室内试验,分别研究了初始饱和的糊状试样和不同压实状态的压实试样的体积收缩变形特征。对于糊状试样,采用液体体积置换法测量了试样干燥过程中的体积变化,获得了完整的收缩曲线,试验结果表明:糊状试样的收缩过程可分正常收缩、残余收缩和零收缩3个阶段;绝大部分收缩变形发生在进气点之前即土体处于饱和状态。对于压实试样,初始干密度和含水率对收缩特征有重要影响:初始干密度增加对体积收缩变形起抑制作用,而初始含水率的增加对体积收缩变形起促进作用。此外,压实试样的体积收缩存在明显的各向异性,且对初始含水率的敏感程度高于%Drying shrinkage is one of the intrinsic characteristics of soil,and has profound effects on its engineering properties.In this investigation,laboratory tests are conducted on initially saturated paste-like specimens and compacted specimens with different compaction parameters.For the paste-like specimens,the fluid volume displacement technique is employed to measure the volumetric change of specimens during drying,and the complete shrinkage curve is determined.It is found that three stages can be distinguished in the shrinkage of paste-like specimens,namely normal shrinkage,residual shrinkage and zero shrinkage;most of the volumetric shrinkage deformation occurs before the air-entry point while the soil is still fully saturated;the volume shrinkage behavior and shrinkage curve shape significantly depend on soil microstructure characteristics.For the compacted specimens,the shrinkage behavior is significantly controlled by the initial drying density and water content.In general,shrinkage strain decreases with the increase of the initial dry density and increases with the increase of the compaction water content.In addition,the results show that the shrinkage of compacted specimens is anisotropic rather than isotropic,and is more

  10. A comparison of measured and calculated values of air kerma rates from 137Cs in soil

    Directory of Open Access Journals (Sweden)

    V. P. Ramzaev

    2016-01-01

    Full Text Available In 2010, a study was conducted to determine the air gamma dose rate from 137Cs deposited in soil. The gamma dose rate measurements and soil sampling were performed at 30 reference plots from the south-west districts of the Bryansk region (Russia that had been heavily contaminated as a result of the Chernobyl accident. The 137Cs inventory in the top 20 cm of soil ranged from 260 kBq m–2 to 2800 kBq m–2. Vertical distributions of 137Cs in soil cores (6 samples per a plot were determined after their sectioning into ten horizontal layers of 2 cm thickness. The vertical distributions of 137Cs in soil were employed to calculate air kerma rates, K, using two independent methods proposed by Saito and Jacob [Radiat. Prot. Dosimetry, 1995, Vol. 58, P. 29–45] and Golikov et al. [Contaminated Forests– Recent Developments in Risk Identification and Future Perspective. Kluwer Academic Publishers, 1999. – P. 333–341]. A very good coincidence between the methods was observed (Spearman’s rank coefficient of correlation = 0.952; P<0.01; on average, a difference between the kerma rates calculated with two methods did not exceed 3%. The calculated air kerma rates agreed with the measured dose rates in air very well (Spearman’s coefficient of correlation = 0.952; P<0.01. For large grassland plots (n=19, the measured dose rates were on average 6% less than the calculated kerma rates. The tested methods for calculating the air dose rate from 137Cs in soil can be recommended for practical studies in radiology and radioecology. 

  11. Concurrent drying of soybean seeds: the effect of the radial air profile

    Directory of Open Access Journals (Sweden)

    A. J. Assis

    2005-06-01

    Full Text Available The aim of this work was to analyze the heat and mass transfer between the air and soybean seeds in a concurrent moving bed dryer with an air profile that is not flat. The modelling of heat and mass transfer in moving bed dryers is generally based on the application of mass and energy balance equations for both solid and fluid phases (two-phase model. In the establishment of these equations some classical hypotheses such as that the fluid velocity profile is flat, are assumed. The main goal of this work was to verify the validity of this assumption by means of an experimental and simulation study in a concurrent moving bed, using soybean seeds as particles. In this work, the radial air profile was taken into account by means of a suitable empirical correlation and a mechanistic model validated by experimental results. The numerical solution of the one-dimension boundary value problem was obtained by means of a computational code based on axial integration through the DASSL code. By comparison of the experimental data and the simulated responses for air temperature and seed moisture content, it was possible to verify the significant effect of air velocity distribution.

  12. Dry deposition of elemental iodine on skin, hair, and clothing from air

    International Nuclear Information System (INIS)

    Hairless rats, clothes, human hair, filter paper and water were exposed to gaseous elemental iodine in a glass chamber for 60-120 minutes. The deposition of gaseous elemental iodine on skin and lung of rats, human hair, water, clothes and paper were investigated by measuring iodine content in the exposed material by epithermal neutron activation analysis (ENAA). For measurement of the iodine concentration in the chamber air, elemental iodine in the air was collected by continuously sucking air through an active charcoal column. The trapped iodine in the active charcoal was then determined by ENAA. The measured deposition velocity in the test chamber of gaseous elemental iodine on skin, clothing, hair and water ranges from 0.006 on filter paper and water to about 0.05 cm/s on skin and clothes. The variation of elemental iodine concentration in air of the glass chamber was investigated by collecting and analyzing air samples at various time intervals. The results show that the variation with time in the concentration of the iodine can be described by an exponential function

  13. Dry sliding wear of Ti-6Al-4V alloy in air and vacuum

    Institute of Scientific and Technical Information of China (English)

    刘勇; 杨德庄; 何世禹; 武万良

    2003-01-01

    Differences in wear rate, morphology of the worn surface and debris, and the microstructure in subsurface of the Ti-6Al-4V alloy after wear in air and vacuum were compared. The wear rate of Ti-6Al-4V alloy in air is higher than that in vacuum in all the ranges of sliding velocities and applied loads. The wear of Ti-6Al-4V alloy in air is controlled by a combination of abrasion, oxidation and delamination with micro-cracks remaining in subsurface. Under the vacuum condition, the surface layer of Ti-6Al-4V alloy experiences a severe plastic deformation on a great scale, which results in an ultra-fine microstructure.

  14. Using air, soil and vegetation to assess the environmental behaviour of siloxanes

    DEFF Research Database (Denmark)

    Ratola, N.; Ramos, S.; Homem, V.;

    2016-01-01

    and pine needles, the results showed total concentration of siloxanes between 5 and 70 ng g(-1) (dry weight) for soils and from 2 to 118 ng g(-1) (dry weight (dw)) for pine needles, with no clear seasonal trend. For SIPs, the levels varied from 0.6 to 7.8 ng m(-3) and were higher in summer than in winter...... foam disks-SIPs), the sampling of pine needles and soil was also performed, thus closing the circle of atmospheric exposure in the areas of study. Two sampling campaigns (one in summer and one in winter) were done in a total of eight sampling points in the Portuguese territory, which covered a wide...

  15. X-ray Amorphous Phases in Antarctica Dry Valley Soils: Insight into Aqueous Alteration Processes on Mars?

    Science.gov (United States)

    Ming, D. W.; Morris, R. V.; Rampe, E. B.; Quinn, J. E.; Graff, T. G.

    2015-12-01

    The Chemistry and Mineralogy (CheMin) instrument onboard the Mars Curiosity rover has detected abundant amounts (approx. 25-30 wt. %) of X-ray amorphous materials in a windblown deposit (Rocknest) and in a sedimentary mudstone (Cumberland and John Klein) in Gale crater. On Earth, X-ray amorphous components are common in soils and sediments, but usually not as abundant as detected in Gale crater. One hypothesis for the abundant X-ray amorphous materials on Mars is limited interaction of liquid water with surface materials, kinetically inhibiting maturation to more crystalline phases. The objective of this study was to characterize the chemistry and mineralogy of soils formed in the Antarctica Dry Valleys, one of the driest locations on Earth. Two soils were characterized from different elevations, including a low elevation, coastal, subxerous soil in Taylor Valley and a high elevation, ultraxerous soil in University Valley. A variety of techniques were used to characterize materials from each soil horizon, including Rietveld analysis of X-ray diffraction data. For Taylor Valley soil, the X-ray amorphous component ranged from about 4 wt. % in the upper horizon to as high as 15 wt. % in the lowest horizon just above the permafrost layer. Transmission electron microscopy indicated that the presence of short-range ordered (SRO) smectite was the most likely candidate for the X-ray amorphous materials in the Taylor Valley soils. The SRO smectite is likely an aqueous alteration product of mica inherited from granitic materials during glaciation of Taylor Valley. The drier University Valley soil had lower X-ray amorphous contents of about 5 wt. % througout the profile. The X-ray amorphous materials in University Valley are attributed to nanoparticles of TiO2 and possibly amorphous SiO2. The high abundance of X-ray amorphous materials in Taylor Valley is surprising for one of the driest places on Earth. These materials may have been physically and chemical altered during

  16. Air pollution: Household soiling and consumer welfare losses

    Science.gov (United States)

    Watson, W.D.; Jaksch, J.A.

    1982-01-01

    This paper uses demand and supply functions for cleanliness to estimate household benefits from reduced particulate matter soiling. A demand curve for household cleanliness is estimated, based upon the assumption that households prefer more cleanliness to less. Empirical coefficients, related to particulate pollution levels, for shifting the cleanliness supply curve, are taken from available studies. Consumer welfare gains, aggregated across 123 SMSAs, from achieving the Federal primary particulate standard, are estimated to range from $0.9 to $3.2 million per year (1971 dollars). ?? 1982.

  17. Modelling of heat and mass transfer in a granular medium during high-temperature air drying. Effect of the internal gas pressure

    Science.gov (United States)

    Othmani, Hammouda; Hassini, Lamine; Lamloumi, Raja; El Cafsi, Mohamed Afif

    2016-02-01

    A comprehensive internal heat and water transfer model including the gas pressure effect has been proposed in order to improve the industrial high-temperature air drying of inserts made of agglomerated sand. In this model, the internal gas phase pressure effect was made perfectly explicit, by considering the liquid and vapour transfer by filtration and the liquid expulsion at the surface. Wet sand enclosed in a tight cylindrical glass bottle dried convectively at a high temperature was chosen as an application case. The model was validated on the basis of the experimental average water content and core temperature curves for drying trials at different operating conditions. The simulations of the spatio-temporal distribution of internal gas pressure were performed and interpreted in terms of product potential damage. Based on a compromise between the drying time and the pressure increase, a simple drying cycle was implemented in order to optimize the drying process.

  18. Vertical profile measurements of soil air suggest immobilization of gaseous elemental mercury in mineral soil.

    Science.gov (United States)

    Obrist, Daniel; Pokharel, Ashok K; Moore, Christopher

    2014-02-18

    Evasion of gaseous elemental Hg (Hg(0)g) from soil surfaces is an important source of atmospheric Hg, but the volatility and solid-gas phase partitioning of Hg(0) within soils is poorly understood. We developed a novel system to continuously measure Hg(0)g concentrations in soil pores at multiple depths and locations, and present a total of 297 days of measurements spanning 14 months in two forests in the Sierra Nevada mountains, California, U.S. Temporal patterns showed consistent pore Hg(0)g concentrations below levels measured in the atmosphere (termed Hg(0)g immobilization), ranging from 66 to 94% below atmospheric concentrations throughout multiple seasons. The lowest pore Hg(0)g concentrations were observed in the deepest soil layers (40 cm), but significant immobilization was already present in the top 7 cm. In the absence of sinks or sources, pore Hg(0)g levels would be in equilibrium with atmospheric concentrations due to the porous nature of the soil matrix and gas diffusion. Therefore, we explain decreases in pore Hg(0)g in mineral soils below atmospheric concentrations--or below levels found in upper soils as observed in previous studies--with the presence of an Hg(0)g sink in mineral soils possibly related to Hg(0)g oxidation or other processes such as sorption or dissolution in soil water. Surface chamber measurements showing daytime Hg(0)g emissions and nighttime Hg(0)g deposition indicate that near-surface layers likely dominate net atmospheric Hg(0)g exchange resulting in typical diurnal cycles due to photochemcial reduction at the surface and possibly Hg(0)g evasion from litter layers. In contrast, mineral soils seem to be decoupled from this surface exchange, showing consistent Hg(0)g uptake and downward redistribution--although our calculations indicate these fluxes to be minor compared to other mass fluxes. A major implication is that once Hg is incorporated into mineral soils, it may be unlikely subjected to renewed Hg(0)g re-emission from

  19. {sup 7}Be concentrations in air, rain water and soil in Cantabria (Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Rodenas, C.; Gomez, J.; Quindos, L.S.; Fernandez, P.L.; Soto, J. [Cantabria Univ. (Spain). Dept. of Medical Physics

    1997-04-01

    {sup 7}Be concentrations present in air, rain water and soil have been measured in the region of Cantabria (Spain) during the last 4 yr. There was a relationship between rainfall and the deposited areal activity of the nuclide at the study site which was consistent with observed annual global rainfall and fallout. (author).

  20. Effects of precipitation regime and soil nitrogen on leaf traits in seasonally dry tropical forests of the Yucatan Peninsula, Mexico.

    Science.gov (United States)

    Roa-Fuentes, Lilia L; Templer, Pamela H; Campo, Julio

    2015-10-01

    Leaf traits are closely associated with nutrient use by plants and can be utilized as a proxy for nutrient cycling processes. However, open questions remain, in particular regarding the variability of leaf traits within and across seasonally dry tropical forests. To address this, we considered six leaf traits (specific area, thickness, dry matter content, N content, P content and natural abundance (15)N) of four co-occurring tree species (two that are not associated with N2-fixing bacteria and two that are associated with N2-fixing bacteria) and net N mineralization rates and inorganic N concentrations along a precipitation gradient (537-1036 mm per year) in the Yucatan Peninsula, Mexico. Specifically we sought to test the hypothesis that leaf traits of dominant plant species shift along a precipitation gradient, but are affected by soil N cycling. Although variation among different species within each site explains some leaf trait variation, there is also a high level of variability across sites, suggesting that factors other than precipitation regime more strongly influence leaf traits. Principal component analyses indicated that across sites and tree species, covariation in leaf traits is an indicator of soil N availability. Patterns of natural abundance (15)N in foliage and foliage minus soil suggest that variation in precipitation regime drives a shift in plant N acquisition and the openness of the N cycle. Overall, our study shows that both plant species and site are important determinants of leaf traits, and that the leaf trait spectrum is correlated with soil N cycling. PMID:26013874

  1. Forecasting wetting and drying of post-wildfire soils in response to precipitation: A time series optimization approach

    Science.gov (United States)

    Basak, A.; Kulkarni, C.; Schmidt, K. M.; Mengshoel, O. J.

    2015-12-01

    Volumetric water content (VWC) in soils is critical for forecasting thresholds for runoff-driven erosion caused by rainfall. Even though theoretical relations (e.g., Richards equation) have been developed to quantify VWC in unsaturated granular soils, site-specific field conditions and hysteresis of suction and VWC in soil preclude their direct use. Although attempts have previously been made to forecast VWC using various time-series models (e.g., autoregressive integrated moving average or ARIMA), these approaches lack hydrologic foundations and perform poorly when used to forecast VWC over time periods longer than 24 hours. In this work, we extend an existing Antecedent Water Index (AWI) based model to express VWC as a function of time and rainfall. AWI models typically overfit data and cannot be used for forecast VWC over long time periods. We developed a new model to overcome this limitation, which accumulates rainfall over a time window and fits a diverse range of wetting and drying curves. Hydraulic redistribution parameters in this model bear resemblance to hydrologic processes driven by gravity and suction. This model reasonably forecasts VWC using only initial VWC values and rainfall forecasts. Experimental VWC data were collected from steep gradient post-wildfire sites in southern California. Rapid landscape change was observed in response to small to moderate rain storms. We formulated a mean-squared error minimization problem over the model parameters and optimized using genetic algorithms. We found that our model fits VWC data for 3 distinct soil textures, each occurring at 3 different depths below the ground surface (5 cm, 15 cm, and 30 cm). Our model successfully forecasts VWC trends, such as drying and wetting rate. To a certain extent, our model achieves spatial and seasonal generalizability. Our accumulative rainfall model is also applicable to continuous predictions, where VWC values are repeatedly used to predict future ones within a 12-hr time

  2. Wheel traffic effect on air-filled porosity and air permeability in a soil catena across the wheel rut

    DEFF Research Database (Denmark)

    Berisso, Feto Esimo; Schjønning, Per; Lamandé, Mathieu;

    than at the periphery of the wheel rut (0.4 m) or outside the wheel rut. At least one of these differences εa was significant at all soil depths . At all matric potentials, the ka was lowest at the periphery of the wheel rut and highest outside the wheel rut, with intermediate values inside the wheel...... catena running from center of the wheel rut to un wheeled part of the field ( 0, 20, 40, 50,60 and 400 cm horizontal distance). We measured water retention and air permeability (ka) at -30, -100 and -300 hPa matric potentials. At -100 hPa, we obtained consistently lower air filled under the wheel rut......The impact of wheel traffic on soil physical properties is usually quantified by randomly collecting soil cores at specific depths below the wheeled surface. However, modeling studies as well as few measurements indicated a non-uniform stress distribution in a catena across the wheel rut, which...

  3. Tribology of ethylene-air diffusion flame soot under dry and lubricated contact conditions

    International Nuclear Information System (INIS)

    Soot particles are generated in a flame caused by burning ethylene gas. The particles are collected thermophoretically at different locations of the flame. The particles are used to lubricate a steel/steel ball on flat reciprocating sliding contact, as a dry solid lubricant and also as suspended in hexadecane. Reciprocating contact is shown to establish a protective and low friction tribo-film. The friction correlates with the level of graphitic order of the soot, which is highest in the soot extracted from the mid-flame region and is low in the soot extracted from the flame root and flame tip regions. Micro-Raman spectroscopy of the tribo-film shows that the a priori graphitic order, the molecular carbon content of the soot and the graphitization of the film as brought about by tribology distinguish between the frictions of soot extracted from different regions of the flame, and differentiate the friction associated with dry tribology from that recorded under lubricated tribology. (paper)

  4. Remediation of arsenic contaminated soil by coupling oxalate washing with subsequent ZVI/Air treatment.

    Science.gov (United States)

    Cao, Menghua; Ye, Yuanyao; Chen, Jing; Lu, Xiaohua

    2016-02-01

    The application of a novel coupled process with oxalate washing and subsequent zero-valent iron (ZVI)/Air treatment for remediation of arsenic contaminated soil was investigated in the present study. Oxalate is biodegradable and widely present in the environment. With addition of 0.1 mol L(-1) oxalate under circumneutral condition, 83.7% and 52.6% of arsenic could be removed from a spiked kaolin and an actual contaminated soil respectively. Much more oxalate adsorption on the actual soil was attributed to the higher soil organic matter and clay content. Interestingly, oxalate retained in the washing effluent could act as an organic ligand to promote the oxidation efficiency of ZVI/Air at near neutral pH. Compared with the absence of oxalate, much more As(III) was oxidized. Arsenic was effectively adsorbed on iron (hydr)oxides as the consumption of oxalate and the increase of pH value. For the actual soil washing effluent, about 94.9% of total arsenic was removed after 120 min's treatment without pH adjustment. It has been demonstrated that As(V) was the dominant arsenic speciation adsorbed on iron (hydr)oxides. This study provides a promising alternative for remediation of arsenic contaminated soil in view of its low cost and environmental benign. PMID:26476769

  5. The effect of wetting and drying cycles on soil chemical composition and their impact on bulk density evaluation

    International Nuclear Information System (INIS)

    The gamma-ray attenuation technique has been applied successfully in several areas of knowledge such as medicine, industry, chemistry, biology, agriculture and so on. Before the technique application it is important to know the probability of gamma photons interaction with the matter. The linear attenuation coefficient (k) measures the probability per unit length of a photon to be absorbed or scattered while interacting with a sample. k represents the sum of several individual attenuation coefficients due mainly to the photoelectric absorption, coherent and incoherent scatterings and pair production. Soil is characterized as a three phase system composed by solid, liquid and gaseous phases. It is known that for a given photon energy the mass attenuation coefficient (μ) is directly related to the chemical composition of the soil. As a consequence by using the mixture rule, in which (μ) is calculated by adding the products of mass attenuation coefficients and the contents of the chemical components of the soil, it is possible to obtain a theoretical (μ) value. A possible cause of chemical composition changes in soil is the application of repeated wetting and drying (W-D) cycles. Another consequence of these changes in the chemical composition of the soil can be alterations in its (μ). This result can affect how well the gamma-ray attenuation or computed tomography (CT) techniques can determine soil bulk density (ds) or porosity (φ) when samples are submitted to W-D cycles. In this work the soil elemental (oxides) composition variation of three Brazilian soils submitted to the application of W-D cycles was measured in order to evaluate possible changes in the calculated μ as a function of the cycles. Measurements of μ by using radioactive sources of 241Am and 137Cs were also performed. Gamma-ray CT was used as a tool to evaluate the impact of changes in μ induced by the cycles in determinations of ds. The measured and calculated values of μ presented good

  6. Soil microbiological properties and enzymatic activities of long-term post-fire recovery in dry and semiarid Aleppo pine (Pinus halepensis M.) forest stands

    Science.gov (United States)

    Hedo, J.; Lucas-Borja, M. E.; Wic, C.; Andrés-Abellán, M.; de Las Heras, J.

    2015-02-01

    Wildfires affecting forest ecosystems and post-fire silvicultural treatments may cause considerable changes in soil properties. The capacity of different microbial groups to recolonise soil after disturbances is crucial for proper soil functioning. The aim of this work was to investigate some microbial soil properties and enzyme activities in semiarid and dry Aleppo pine (Pinus halepensis M.) forest stands. Different plots affected by a wildfire event 17 years ago without or with post-fire silvicultural treatments 5 years after the fire event were selected. A mature Aleppo pine stand, unaffected by wildfire and not thinned was used as a control. Physicochemical soil properties (soil texture, pH, carbonates, organic matter, electrical conductivity, total N and P), soil enzymes (urease, phosphatase, β-glucosidase and dehydrogenase activities), soil respiration and soil microbial biomass carbon were analysed in the selected forests areas and plots. The main finding was that long time after this fire event produces no differences in the microbiological soil properties and enzyme activities of soil after comparing burned and thinned, burned and not thinned, and mature plots. Moreover, significant site variation was generally seen in soil enzyme activities and microbiological parameters. We conclude that total vegetation recovery normalises post-fire soil microbial parameters, and that wildfire and post-fire silvicultural treatments are not significant factors affecting soil properties after 17 years.

  7. Energy and Water Balance at Soil-Air Interface in a Sahelian Region

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The aim of this work is an improvement of the parameterization of the soil moisture in the scheme of the Land Surface Process Model (LSPM) for applications over desert areas. In fact, in very dry conditions, the water vapour flux plays an important role in the evaporation processes and influences the underground profiles of humidity and temperature. The improved version of soil moisture parametcrization in the LSPM scheme has been checked by using the data taken from the database of the field experiment HAPEX-Sahel (Hydrology-Atmosphere Pilot Experiment in the Sahel, 1990-1992). Model simulations refer to three dif ferent stations located in Niger (Fallow, Millet and Tiger sites) where input data for LSPM and observations were simultaneously available. The results of simulations taking into account the water vapour flux in the soil model LSPM, seem to compare better with the observed behaviour of soil moisture and turbulent heat fluxes than those overlooking the water vapour flux, confirming the great importance of the water vapour in such dry conditions.

  8. Ozone production using a power modulated surface dielectric barrier discharge in dry synthetic air

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Pekárek, S.; Prukner, Václav

    2012-01-01

    Roč. 32, č. 4 (2012), s. 743-754. ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA202/09/0176 Institutional research plan: CEZ:AV0Z20430508 Keywords : ozone * surface DBD * synthetic air * nitrogen oxides * production efficiency Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.728, year: 2012 http://www.springerlink.com/content/h7p1j46381150510/fulltext.pdf

  9. Air Mass Back Trajectories and Dry Atmospheric Aerosol Mass Size Distributions in Prague

    Czech Academy of Sciences Publication Activity Database

    Schwarz, Jaroslav; Štefancová, Lucia; Maenhaut, W.; Smolík, Jiří; Ždímal, Vladimír

    Prague: Czech Aerosol Society, 2013, A228. ISBN N. [European Aerosol Conference (EAC 2013). Prague (CZ), 01.09.2013-06.09.2013] R&D Projects: GA ČR GAP209/11/1342 Institutional support: RVO:67985858 Keywords : mass size distribution * air mass back trajectories * water soluble ions Subject RIV: CF - Physical ; Theoretical Chemistry http://eac2013.cz/index.php

  10. Assessing dry density and gravimetric water content of soils in geotechnics with complex conductivity measurements : preliminary investigations

    Science.gov (United States)

    Kaouane, C.; Beck, Y.; Fauchard, C.; Chouteau, M.

    2012-12-01

    Quality controls of geotechnical works need gravimetric water content (w) and dry density (γd) measurements. Afterwards, results are compared to Proctor tests and referred to soil classification. Depending on the class of soils, different objectives must be achieved. Those measurements are usually carried out with neutron and gamma probes. Combined use of theses probes directly access (w, γd). Theses probes show great disadvantages as: nuclear hazard, heavy on-site, transporation and storage restrictions and low sampling volumes. Last decades showed a strong development of electrical and electromagnetic methods for mapping water content in soils. Still, their use in Geotechnics is limited due to interfacial effects neglected in common models but strong in compacted soils. We first showed that (w, γd) is equivalent to (φ, Sr) assuming density of particles γs=2.7 (g.cm-3). This assumption is true for common soils used in civil engineering. That first relationship allows us to work with meaningful parameters for geophysicists. Revil&Florsh recently adapted Vinegar&Waxman model for Spectal Induced Polarization (SIP) measurements at low frequencies (samples were compacted at Proctor energy. We assessed (w, γd) by weighting and drying samples. We obtained γd = 1.6-1.9 (g.cm-3) and w=7-14% which lead to φ=0.3-0.4 and Sr=0.3-0.8. Tap water (ρw= 30 Ω.m) was used for the experiment. We first evaluated the saturation factor n=1.35 by fitting a power law ρ/ρw =a*Sr^n+b. a=0.223 agreed with φ^(-n)=F, F being the formation factor. This leads to a mean tortuosity α=1.47. b=0.5 might be related to surface conductivity. An empirical Rhoades-Corwin model also fit great to data. Revil&Florsh model allows us to predict a phase peak in case of complex conductivity measurements. We predicted a frequency peak at 2.4 Hz. This peak is well located in the frequency range of SIP (from 1 mHz to ~10 Hz). At the frequency peak, this model allows the direct evaluation of saturation

  11. Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

    OpenAIRE

    M. J. van der Ploeg; Gooren, H. P. A.; Bakker, G.; Hoogendam, C. W.; Huiskes, C.; Koopal, L.K.; Kruidhof, H.; Rooij, G. H.

    2010-01-01

    Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately −0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed polymer tensiometers (POTs) are able to directly measure soil matric potentials until the theoretical wilting point (−1.6 MPa). By minimizing the volume of polymer solution inside the POT while maximi...

  12. Variability of Arundo donax growth in dry-farming as a function of soil properties

    OpenAIRE

    Mauri, Pedro Vicente; Plaza, Antonio; Guerrero, A. M.; Curt Fernández de la Mora, Mª Dolores; Sanz Gallego, Marina; Fernandez Gonzalez, Jesus

    2014-01-01

    Arundo donax L., commonly known as giant reed or arundo, is a perennial rhizomatous grass that has been studied since the decade of 1980 for bioenergy. In the Mediterranean region -characterised by dry and hot summers- arundo is usually grown with the support of irrigation. However, there is evidence that this plant species can tolerate dry-farming conditions once the crop is fully established. In this work the variation observed in plant growth of a 5-year-old arundo crop when the managemen...

  13. Physiological and biochemical responses of Yarrowia lipolytica to dehydration induced by air-drying and freezing.

    Directory of Open Access Journals (Sweden)

    Caroline Pénicaud

    Full Text Available Organisms that can withstand anhydrobiosis possess the unique ability to temporarily and reversibly suspend their metabolism for the periods when they live in a dehydrated state. However, the mechanisms underlying the cell's ability to tolerate dehydration are far from being fully understood. The objective of this study was to highlight, for the first time, the cellular damage to Yarrowia lipolytica as a result of dehydration induced by drying/rehydration and freezing/thawing. Cellular response was evaluated through cell cultivability determined by plate counts, esterase activity and membrane integrity assessed by flow cytometry, and the biochemical composition of cells as determined by FT-IR spectroscopy. The effects of the harvesting time (in the log or stationary phase and of the addition of a protective molecule, trehalose, were investigated. All freshly harvested cells exhibited esterase activity and no alteration of membrane integrity. Cells freshly harvested in the stationary phase presented spectral contributions suggesting lower nucleic acid content and thicker cell walls, as well as longer lipid chains than cells harvested in the log phase. Moreover, it was found that drying/rehydration induced cell plasma membrane permeabilization, loss of esterase activity with concomitant protein denaturation, wall damage and oxidation of nucleic acids. Plasma membrane permeabilization and loss of esterase activity could be reduced by harvesting in the stationary phase and/or with trehalose addition. Protein denaturation and wall damage could be reduced by harvesting in the stationary phase. In addition, it was shown that measurements of loss of membrane integrity and preservation of esterase activity were suitable indicators of loss and preservation of cultivability, respectively. Conversely, no clear effect of freezing/thawing could be observed, probably because of the favorable operating conditions applied. These results give insights into Y

  14. An economic optimization of evaporator and air collector area in a solar assisted heat pump drying system

    International Nuclear Information System (INIS)

    Highlights: • The optimum combination will provide around 89% of the total load. • The system has a savings during the life cycle with least payback period of 4.37 year. • The optimal system is insensitive to the variation in fuel inflation and discount rate. - Abstract: This paper presents an economic optimization of evaporator and air collector area of a solar assisted heat pump drying system. Economic viability of solar heating systems is usually made by comparing the cost flows recurring throughout the lifetime of the solar and conventional alternative systems. Therefore, identification of optimum variables by using a simulation program and an economic analysis based on payback period of the system are presented in this paper. FORTRAN language is used to run the simulation. Effect of load and different economic variables on payback period is also investigated. Economic analysis reveals that system has sufficient amount of savings during the life cycle with a minimum payback period of about 4 years

  15. Three years of greenhouse gas column-averaged dry air mole fractions retrieved from satellite – Part 1: Carbon dioxide

    Directory of Open Access Journals (Sweden)

    R. Macatangay

    2008-03-01

    Full Text Available Carbon dioxide (CO2 and methane (CH4 are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. We have processed three years (2003–2005 of SCIAMACHY near-infrared nadir measurements to simultaneously retrieve vertical columns of CO2 (from the 1.58 μm absorption band, CH4 (1.66 μm and oxygen (O2 A-band at 0.76 μm using the scientific retrieval algorithm WFM-DOAS. We show that the latest version of WFM-DOAS, version 1.0, which is used for this study, has been significantly improved with respect to its accuracy compared to the previous versions while essentially maintaining its high processing speed (~1 minute per orbit, corresponding to ~6000 single measurements, and per gas on a standard PC. The greenhouse gas columns are converted to dry air column-averaged mole fractions, denoted XCO2 (in ppm and XCH4 (in ppb, by dividing the greenhouse gas columns by simultaneously retrieved dry air columns. For XCO2 dry air columns are obtained from the retrieved O2 columns. For XCH4 dry air columns are obtained from the retrieved CO2 columns because of better cancellation of light path related errors compared to using O2 columns retrieved from the spectrally distant O2 A-band. Here we focus on a discussion of the XCO2 data set. The XCH4 data set is discussed in a separate paper (Part 2. In order to assess the quality of the retrieved XCO2 we present comparisons with Fourier Transform Spectroscopy (FTS XCO2 measurements at two northern hemispheric mid-latitude ground stations. To assess the quality globally, we present detailed comparisons with global XCO2 fields obtained from NOAA's CO2 assimilation system CarbonTracker. For the Northern Hemisphere we find good agreement with the reference data for the CO2 seasonal cycle and the CO2

  16. Short-term impact of dry olive mill residue addition to soil on the resident microbiota

    Czech Academy of Sciences Publication Activity Database

    Sampedro, I.; Giubilei, M. A.; Cajthaml, Tomáš; Federici, E.; Federici, F.; Petruccioli, M.; D´Annibale, A.

    2009-01-01

    Roč. 100, č. 23 (2009), s. 6098-6106. ISSN 0960-8524 R&D Projects: GA MŠk LC06066 Institutional research plan: CEZ:AV0Z50200510 Keywords : Dry olive mill residue * Microbial community profiling * Toxicity Subject RIV: EE - Microbiology, Virology Impact factor: 4.253, year: 2009

  17. Heterogeneous photochemical reactions of a propylene-nitrogen dioxide-metal oxide-dry air system

    Science.gov (United States)

    Takeuchi, Koji; Ibusuki, Takashi

    Photochemical reactions of a C 3H 6-NO 2-air system in the presence of metal oxide were investigated. The metal oxides showing strong photooxidation activity were found to be n-type semiconductor oxides with the energy band gap around 3 eV. Formation of cyano-compounds (HCN and CH 3CN) was also observed and the activity can be explained in terms of the adsorptivity of NO onto metal oxides. Coalfired fly ash as a model of mixed metal oxides was also examined and their photocatalytic action was discussed.

  18. Modelling and simulation of a Three-Stage Air Compressor Based on Dry Piston Technology

    OpenAIRE

    Heidari, Mahbod; Barrade, Philippe; Rufer, Alfred

    2011-01-01

    The core of this modelling is to study heat transfer and fluid dynamics processes for a compression expansion system, and the main particularity is that heat transfer and air movement are due to the movement of the piston. We have implemented a "moving mesh" solver to compute the volume changes of the compression chamber followed by a "Fluid dynamics" type solver. It allows correct computation of the fluid behavior in the system and enable us to identify the pressure change of the fluid, and ...

  19. Measurement of radioactive soil contamination from the air

    International Nuclear Information System (INIS)

    In-situ gamma spectrometry can be used to determine the qualitative and quantitative deposition of radioactive materials on the ground surface. By applying the in-situ spectrometry method using either a helicopter or an airplane, large areas can be scanned in a short period of time. In this report the results of in-situ gamma spectroscopic measurements taken from a helicopter are described. Measurements were carried out using a single point source, a field of 36 point sources, and using the present ground contamination due to fall-out from the Chernobyl accident and atom bombs. The results of these measurements were used to determine calibration factors, which were in agreement with a calibration obtained using more simple (and less expensive) laboratory measurements in combination with flux calculations. Detection limits for the measurement of surface contamination were determined. At a height of 50 meters above the surface and using a measurement time of 2 minutes, the minimally detectable surface contamination was 1.1 kBqm-2 for a Cs-137 contamination and 2.1 kBqm-2 for I-131 contamination. Fall-out determinations based on measurements taken at a height of 50 meters were in agreement with determinations taken at a height of 1 meter, and with the results obtained measuring soil samples. The in-situ gamma spectroscopy, using helicopter or airplane, is a fast and powerful method for mapping surface contamination. (author). 13 refs.; 18 figs.; 13 tabs

  20. Soil microbiological properties and enzymatic activities of long-term post-fire recovery in dry and semiarid Aleppo pine (Pinus halepensis M. forest stands

    Directory of Open Access Journals (Sweden)

    J. Hedo

    2014-10-01

    Full Text Available Wildfires affecting forest ecosystems and post-fire silvicultural treatments may cause considerable changes in soil properties. The capacity of different microbial groups to recolonize soil after disturbances is crucial for proper soil functioning. The aim of this work was to investigate some microbial soil properties and enzyme activities in semiarid and dry Aleppo pine (Pinus halepensis M. forest stands. Different plots affected by a wildfire event 17 years ago without or with post-fire silvicultural treatments five years after the fire event were selected. A mature Aleppo pine stand unaffected by wildfire and not thinned was used as a control. Physicochemical soil properties (soil texture, pH, carbonates, organic matter, electrical conductivity, total N and P, soil enzymes (urease, phosphatase, β-glucosidase and dehydrogenase activities, soil respiration and soil microbial biomass carbon were analysed in the selected forests areas and plots. The main finding was that long time after this fire event produces no differences in the microbiological soil properties and enzyme activities of soil after comparing burned and thinned, burned and not thinned, and mature plots. Thus, the long-term consequences and post-fire silvicultural management in the form of thinning have a significant effect on the site recovery after fire. Moreover, significant site variation was generally seen in soil enzyme activities and microbiological parameters. We conclude that total vegetation restoration normalises microbial parameters, and that wildfire and post-fire silvicultural treatments are not significant factors of soil properties after 17 years.

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

    Science.gov (United States)

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

    2011-12-01

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

  2. 自然干燥与热风干燥对甘薯粉丝质量的影响%Effcets of Natural Drying and Hot-air Drying on Quality of Sweet Potato Vermicelli

    Institute of Scientific and Technical Information of China (English)

    周洁; 孔晓玲

    2011-01-01

    This article researches on the quality comparison of natural drying and hot air drying of sweet potato vermicelli, by the appearance of shape, swelling rate, break off rate, tensile properties . Analyses the effect of different dry methods on sweet potato vermicelli, points out the reasonable dry method of vermicelli.%对自然干燥与热风干燥的甘薯粉丝进行了质量对比,通过外观形状、膨润度、断条率、抗拉性等几个方面的观察与检测,分析了不同的干燥方法对粉丝干燥特性的影响,并给出了粉丝干燥方式的合理化建议.

  3. Effect of hot air drying on volatile compounds of Flammulina velutipes detected by HS-SPME-GC-MS and electronic nose.

    Science.gov (United States)

    Yang, Wenjian; Yu, Jie; Pei, Fei; Mariga, Alfred Mugambi; Ma, Ning; Fang, Yong; Hu, Qiuhui

    2016-04-01

    Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes. PMID:26593566

  4. A Numerical Study of the Impacts of Dry Air on Tropical Cyclone Formation: A Development Case and a Non-development Case

    Science.gov (United States)

    Fritz, C.; Wang, Z.

    2012-12-01

    The impacts of dry air on tropical cyclone formation are examined in the numerical model simulations of ex-Gaston (2010) and pre-Fay (2008). The former, a remnant low downgraded from a short-lived tropical cyclone, can be regarded as a non-developing system as it failed to redevelop, and the latter developed into a tropical cyclone despite lateral dry air entrainment and a transient upper-level dry air intrusion. Water vapor budget analysis suggests that the mean vertical moisture transport plays the dominant role in moistening the free atmosphere. Backward trajectory analysis and water budget analysis show that vertical transport of dry air from the middle and upper troposphere, where a well-defined wave pouch is absent, contributes to the mid-level drying near the pouch center in ex-Gaston. The mid-level drying suppresses deep convection, reduces moisture supply from the boundary layer, and contributes to the non-development of ex-Gaston. Three-dimensional trajectory analysis based on the numerical model simulation of Fay suggests that dry air entrained at the pouch periphery tends to stay off the pouch center due to the weak mid-level inflow or gets moistened along its path even if being wrapped into the wave pouch. Lateral entrainment in the middle troposphere thus does not suppress convection near the pouch center or prevent the development of Tropical Storm Fay. This study suggests that the upper troposphere is a weak spot of the wave pouch at the early formation stage and that the vertical transport is likely a more direct pathway for dry air to influence moist convection near the pouch center. Fig. 1 (a) 3 km relative humidity and storm relative streamlines for Gaston (2010) at 0800 UTC 05 September 2010 with a group of ensemble forward parcel trajectories (gray); (b) vertical cross section of RH along 17.5°N (contour intervals are set to 15%) and backward trajectories (gray) projected on the longitude-height plane. The box in (a) highlights a pocket of

  5. Use of a horizontal air-dispersion system to enhance biodegradation of diesel fuel contaminated soils

    International Nuclear Information System (INIS)

    A horizontal air-dispersion system was designed and installed to enhance the natural biodegradation of residual diesel fuel contaminated soils at an underground storage tank (UST) facility in Seattle, Washington. This system was designed to operate in conjunction with an existing free-product recovery system which exposes more heavily contaminated soils at the capillary fringe to injected air. Results of a pilot study conducted at the facility indicate that an initial biodegradation rate of 2,200 mg of total petroleum hydrocarbons (TPH) per kg of soil per year will be achieved, making in-situ biodegradation a feasible remedial alternative for contaminated site soils. Oxygen, carbon dioxide, and hydrocarbon vapor concentrations have been monitored since full-scale startup in September 1992, using a series of vapor monitoring points (VMPs) installed in the vicinity of the aerated beds and around the perimeter of the facility. Recent monitoring data indicate that the system is capable of aerating soils at distances greater than 80 feet from the aerated beds. Oxygen utilization and carbon dioxide production measured during post-startup respiration tests indicate microbial activity has increased as a result of seven months of full-scale system operation

  6. Monitoring of the vegetable garden open air spinach and soil radioactivity in Beijing during the Japan Fukushima nuclear accident

    International Nuclear Information System (INIS)

    Objective: To detect artificial radionuclide content in the spinach and soil in open air vegetable garden in Beijing during Fukushima nuclear accident and to study the radioactive contamination characteristics of the samples. Methods: 6 spinach samples and 3 soil samples in open air vegetable garden were obtained through continuously sampling. High-purity germanium (HPGe) γ spectrometry was used to analyze activity concentrations of artificial radionuclide131I etc in these samples. Results: Artificial radionuclide 131I was detected in the 6 open air spinach samples. Artificial radionuclide 137Cs was detected in 3 vegetable garden soil samples, trace amount of 131I was detected in 1 open-air surface soil sample alone. Conclusions: Following the Fukushima nuclear accident, spinach in Beijing's open-air vegetable garden was slightly polluted by artificial radionuclide 131I, with the highest values of pollution appeared around April 4, 2011, but it could not cause harm to human health. (authors)

  7. Research on Wetting-Drying Cycles’ Effect on the Physical and Mechanical Properties of Expansive Soil Improved by OTAC-KCl

    Directory of Open Access Journals (Sweden)

    Bao-tian Wang

    2015-01-01

    Full Text Available Expansive soil experiences periodic swelling and shrinkage during the alternate wet and dry environments, which will result in severe damage to the slope stability. In this study, a promising modifier OTAC-KCl is introduced, which has a good diffusivity and is soluble in water or other solvents easily. Firstly, a reasonable combination of ameliorant 0.3% STAC and 3% KCl is chosen referring to the free swell test. Then, the best curing period, 14 days, is gotten from UCS tests. The effect of wetting and drying cycles on engineering properties of expansive soil improved by OTAC-KCl admixtures after 14-day curing is also studied accordingly. Both treated and untreated expansive soil samples are prepared for the cyclic wetting-drying tests which mainly include cyclic swelling potential and cyclic strength tests. Experimental results show that the swelling potential of expansive soil samples stabilized with OTAC-KCl is suppressed efficiently, and the untreated soil specimens will collapse when immersed in water while the treated specimens keep in good conditions. Moreover, expansive soil samples modified with 0.3% OTAC + 3% KCl show enough durability on the swelling ability, shear strength, and unconfined compressive strength, which means, that both the physical and the mechanical properties of stabilized expansive soil have been improved effectively.

  8. Radioecological investigations in the food-chain air-soil-vine-wine. Pt. 2

    International Nuclear Information System (INIS)

    This Part 2 presents all of the results, including the harvest of 1986 and 1987; it thus describes the consequences of the Chernobyl accident. H-3, C-14, Sr-90 and Cs-137 were determined in soil, vine leaves, grapes and wine at different locations. In some of the samples Cs-134, K-40 and Ra-226 were also measured. Site-specific transfer factors were calculated for Sr-90 and for the Cs radionuclides. The mean content of Cs-137 before Chernobyl (after Chernogyl) was about 4 (9) Bq/kg dry matter in soil (top 30 cm), 0.07 (3) Bq/kg fresh matter in leaves, 0.02 (0.4) Bq/kg FM in grapes, and 0.008 (0.9) Bq/l in wine. As comapred to 1986 distinctly lower levels were found in leaves, grapes and wine from 1987. The content of Cs-134 was about half that of Cs-137 in 1986. Due to its shorter half-life Cs-134 had fallen below detection limit in many of the 1987 samples. Mean Sr-90 levels were 1-2 Bq/kg in soil and in leaves (dry matter and fresh matter, respectively), 19-56 mBq/kg in grapes, and 3-11 mBq/l in wine. Samples obtained in the fall of 1986 showed no increase of Sr-90 in soil and leaves, whereas a slight increase was found in grapes and wine as a consequence of Chernobyl. Site-specific influences such als soil parameters, climate, cultivation, vinification and differences between years had no pronounced effects on transfer factors. No influence of the nuclear power station Neckarwestheim has been found in any of the radionuclides. (orig./HP)

  9. Dried gamma-irradiated sewage solids use on calcareous soils: crop yeilds and heavy metals uptake

    International Nuclear Information System (INIS)

    Experiments designed to examine gamma-radiation effects on extractable and plant-available sludge elements and to examine the response of crops to sludge applications on two typical, calcareous soils in New Mexico are summarized. Information has been given indicating that the radiation process of reducing pathogens in sewage products being developed by Sandia Laboratories, does not significantly increase the chemical extractability and plant uptake of a broad range of nutrients and heavy metals. However, radiation treatment greatly facilitates handling sewage for experimentation, because pathogen contamination precautions are eliminated and weed seeds killed. Studies on the effects of sludge irradiation on plant nutrient uptake revealed no concentration increases, agreeing with results presented herein. Sewage products may have special potential for use on calcareous soils, such as in New Mexico. For instance, in New Mexico the lack of potassium in sewage products is not a problem and the naturally high pH of New Mexico soil greatly reduces plant availability of many problem heavy metals. Dramatic increases in yield are typified by the greenhouse and field results presented herein, especially for the known micronutrient deficient soils of New Mexico. Results indicate that sewage sludge is an excellent Zn and Fe fertilizer. More research needs to be done before the economics of sludge application can be calculated and more field information is needed before irradiated sewage products are used indiscriminately

  10. Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

    NARCIS (Netherlands)

    Ploeg, van der M.J.; Gooren, H.P.A.; Bakker, G.; Hoogendam, C.W.; Huiskes, C.; Koopal, L.K.; Kruidhof, H.; Rooij, de G.H.

    2010-01-01

    Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately -0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed pol

  11. Dried gamma-irradiated sewage solids use on calcareous soils: crop yeilds and heavy metals uptake

    Energy Technology Data Exchange (ETDEWEB)

    McCaslin, B.D.; Sivinski, J.S.

    1979-01-01

    Experiments designed to examine gamma-radiation effects on extractable and plant-available sludge elements and to examine the response of crops to sludge applications on two typical, calcareous soils in New Mexico are summarized. Information has been given indicating that the radiation process of reducing pathogens in sewage products being developed by Sandia Laboratories, does not significantly increase the chemical extractability and plant uptake of a broad range of nutrients and heavy metals. However, radiation treatment greatly facilitates handling sewage for experimentation, because pathogen contamination precautions are eliminated and weed seeds killed. Studies on the effects of sludge irradiation on plant nutrient uptake revealed no concentration increases, agreeing with results presented herein. Sewage products may have special potential for use on calcareous soils, such as in New Mexico. For instance, in New Mexico the lack of potassium in sewage products is not a problem and the naturally high pH of New Mexico soil greatly reduces plant availability of many problem heavy metals. Dramatic increases in yield are typified by the greenhouse and field results presented herein, especially for the known micronutrient deficient soils of New Mexico. Results indicate that sewage sludge is an excellent Zn and Fe fertilizer. More research needs to be done before the economics of sludge application can be calculated and more field information is needed before irradiated sewage products are used indiscriminately. (ERB)

  12. Drivers of soil drying in the Czech Republic between 1961 and 2012

    Czech Academy of Sciences Publication Activity Database

    Trnka, M.; Brázdil, R.; Balek, J.; Semerádová, D.; Hlavinka, P.; Možný, M.; Štepánek, P.; Dobrovolný, P.; Zahradníček, P.; Dubrovský, Martin; Eitzinger, J.; Fuchs, B.; Svoboda, M.; Hayes, M.; Žalud, Z.

    2015-01-01

    Roč. 35, č. 9 (2015), s. 2664-2675. ISSN 0899-8418 Institutional support: RVO:68378289 Keywords : pan evaporation * soil moisture * reference evapotranspiration * drought climatology * water balance * observed climate change Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.157, year: 2014 http://onlinelibrary.wiley.com/doi/10.1002/joc.4167/abstract

  13. The ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry Valleys

    OpenAIRE

    Magalhães, Catarina M.; Machado, Ana; Frank-Fahle, Béatrice; Lee, Charles K; Cary, S. Craig

    2014-01-01

    The McMurdo Dry Valleys of Antarctica are considered to be one of the most physically and chemically extreme terrestrial environments on the Earth. However, little is known about the organisms involved in nitrogen transformations in these environments. In this study, we investigated the diversity and abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in four McMurdo Dry Valleys with highly variable soil geochemical properties and climatic conditions: Miers Valley, Upper Wright Va...

  14. Assessing dry density and gravimetric water content of soils in geotechnics with complex conductivity measurements : preliminary investigations

    Science.gov (United States)

    Kaouane, C.; Beck, Y.; Fauchard, C.; Chouteau, M.

    2012-12-01

    Quality controls of geotechnical works need gravimetric water content (w) and dry density (γd) measurements. Afterwards, results are compared to Proctor tests and referred to soil classification. Depending on the class of soils, different objectives must be achieved. Those measurements are usually carried out with neutron and gamma probes. Combined use of theses probes directly access (w, γd). Theses probes show great disadvantages as: nuclear hazard, heavy on-site, transporation and storage restrictions and low sampling volumes. Last decades showed a strong development of electrical and electromagnetic methods for mapping water content in soils. Still, their use in Geotechnics is limited due to interfacial effects neglected in common models but strong in compacted soils. We first showed that (w, γd) is equivalent to (φ, Sr) assuming density of particles γs=2.7 (g.cm-3). This assumption is true for common soils used in civil engineering. That first relationship allows us to work with meaningful parameters for geophysicists. Revil&Florsh recently adapted Vinegar&Waxman model for Spectal Induced Polarization (SIP) measurements at low frequencies (geotechnical campaigns. In-phase conductivity would be mostly related to saturation as quadrature conductivity would be related to porosity and surface conductivity. Although this model was developed for oil-bearing sands, we investigated its potential for compacted soils. Former DC-resistivity (ρ) measurements were carried out on a silty fined-grained soil (A1 in GTR classification or ML-CL in USCS) in a cylindrical cell (radius ~4 cm, heigth 7 cm). Median diameter of grain was 50 μm. For each measurement, samples were compacted at Proctor energy. We assessed (w, γd) by weighting and drying samples. We obtained γd = 1.6-1.9 (g.cm-3) and w=7-14% which lead to φ=0.3-0.4 and Sr=0.3-0.8. Tap water (ρw= 30 Ω.m) was used for the experiment. We first evaluated the saturation factor n=1.35 by fitting a power law

  15. Linking air and water transport in intact soils to macropore characteristics inferred from X-ray computed tomography

    DEFF Research Database (Denmark)

    Katuwal, S.; Nørgaard, Trine; Møldrup, Per;

    2015-01-01

    Soil macropores often control fluid flow and solute transport, and quantification of macropore characteristics including their variability in space and time are essential to predict soil hydraulic and hydrogeochemical functions. In this study, measurements of air and solute transport properties and...... direct macropore visualization by X-ray CT scanning were carried out on 17 large (19-cm diam.; 20-cm length) undisturbed soil columns sampled across a field site (Silstrup, Denmark) with natural gradients in texture and density. Air permeability (ka) at in-situ water content and -20 hPa of matric...... understand field scale variations in gas and solute transport properties as influenced by soil structure and density....

  16. Impact of soil drought on leaf growth of a teak plantation in a dry tropical region and the subsequent impact of leaf area on both canopy net assimilation and evapotranspiration

    Science.gov (United States)

    Tanaka, Katsunori

    2010-05-01

    The current study demonstrated the interannual variations from the beginning of leaf expansion to the peak at a stand level in a dry tropical climate of northern Thailand. Radiative transmittance was measured from March-July in 2001-2008, and seasonal changes in leaf area were qualitatively estimated based on this time series. Soil moisture was also measured, and its influence on leaf growth was shown. Next, a soil-plant-air (SPAC) continuum multilayer model was used to numerically simulate net canopy assimilation (An) and evapotranspiration (ET) for 8 years, to examine the seasonal changes in LAI on An and ET. Two numerical experiments with different seasonal patterns of LAI were carried out using above-canopy hydro-meteorological data as input data. The first experiment involved seasonally varying LAI estimated based on time-series of radiative transmittance through the canopy, and the second experiment applied a constant LAI (or the peak values of LAI) after the flushing. In the first simulation, the simulated transpiration agreed with seasonal changes in heat pulse velocity, corresponding to the water use of individual trees. In the second numerical simulations, the constant LAI increased transpiration at small LAI, particularly immediately after leaf flush. But, the seasonal changes in simulated transpiration were apparently similar to those in observed heat pulse velocity. This implies that soil water, which is balanced in SPAC systems by precipitation, canopy interception, soil evaporation, soil water uptake by transpiration, and discharge, can mainly control the seasonal changes in transpiration. The simulated An became negative under soil drought during the leaf expansion stage in the second simulation, while it became positive or slightly negative even under soil drought in the first simulation. Thus, the limitation of leaf expansion rate caused by soil drought can be favorable for carbon gain.

  17. Experimental research on the mixed sand ratio and initial dry density of weathered sand improved expansive soil free load swelling rate

    Institute of Scientific and Technical Information of China (English)

    Yang Jun; Yang Zhi; Zhang Guodong; Tang Yunwei; Chen Hongping

    2014-01-01

    In this paper,through the indoor free load swelling rate test,expansive soil in a section of a first-class highway reconstruction project in Yichang City was studied. It emphatically analyzed the interrelations among free load swelling rate,non-load time,the proportion of mixed sand and initial dry density. Experimen-tal studies have shown that:Free load swelling deformation is mainly divided into three stages of rapid expan-sion,slow expansion and final stability;when the initial dry density is constant,free load swelling rate of the weathered sand modified soil will reduce rapidly before they slow down with the increase of sand proportion, and weathered sand modified soil free load swelling rate is not sensitive to the large amount of sand mixed;in the same mixed sand ratio,weathered sand modified soil free load swelling rate increases rapidly with the in-crease of initial dry density,there is a good linear correlation between them. To take appropriate control of the initial dry density during the expansive soil subgrade construction helps to reduce its swelling deformation and ensures the stability of the embankment.

  18. Experimental research on the mixed sand ratio and initial dry density of weathered sand improved expansive soil free load swelling rate

    Institute of Scientific and Technical Information of China (English)

    Yang Jun; Yang Zhi; Zhang Guodong; Tang Yunwei; Chen Hongping

    2014-01-01

    In this paper, through the indoor free load swelling rate test, expansive soil in a section of a first- class highway reconstruction project in Yichang City was studied. It emphatically analyzed the interrelations among free load swelling rate, non-load time, the proportion of mixed sand and initial dry density. Experimen- tal studies have shown that: Free load swelling deformation is mainly divided into three stages of rapid expan- sion, slow expansion and final stability; when the initial dry density is constant, free load swelling rate of the weathered sand modified soil will reduce rapidly before they slow down with the increase of sand proportion, and weathered sand modified soil free load swelling rate is not sensitive to the large amount of sand mixed; in the same mixed sand ratio, weathered sand modified soil free load swelling rate increases rapidly with the in- crease of initial dry density, there is a good linear correlation between them. To take appropriate control of the initial dry density during the expansive soil subgrade construction helps to reduce its swelling deformation and ensures the stability of the embankment.

  19. AirMOSS P-Band Radar Retrieval of Subcanopy Soil Moisture Profile

    Science.gov (United States)

    Tabatabaeenejad, A.; Burgin, M. S.; Duan, X.; Moghaddam, M.

    2013-12-01

    Knowledge of soil moisture, as a key variable of the Earth system, plays an important role in our under-standing of the global water, energy, and carbon cycles. The importance of such knowledge has led NASA to fund missions such as Soil Moisture Active and Passive (SMAP) and Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS). The AirMOSS mission seeks to improve the estimates of the North American Net Ecosystem Exchange (NEE) by providing high-resolution observations of the root zone soil moisture (RZSM) over regions representative of the major North American biomes. AirMOSS flies a P-band SAR to penetrate vegetation and into the root zone to provide estimates of RZSM. The flights cover areas containing flux tower sites in regions from the boreal forests in Saskatchewan, Canada, to the tropical forests in La Selva, Costa Rica. The radar snapshots are used to generate estimates of RZSM via inversion of a scattering model of vegetation overlying soils with variable moisture profiles. These retrievals will be used to generate a time record of RZSM, which will be integrated with an ecosystem demography model in order to estimate the respiration and photosynthesis carbon fluxes. The aim of this work is the retrieval of the moisture profile over AirMOSS sites using the collected P-band radar data. We have integrated layered-soil scattering models into a forest scattering model; for the backscattering from ground and for the trunk-ground double-bounce mechanism, we have used a layered small perturbation method and a coherent scattering model of layered soil, respectively. To estimate the soil moisture profile, we represent it as a second-order polynomial in the form of az2 + bz + c, where z is the depth and a, b, and c are the coefficients to be retrieved from radar measurements. When retrieved, these coefficients give us the soil moisture up to a prescribed depth of validity. To estimate the unknown coefficients of the polynomial, we use simulated

  20. Novel Approach for the Remediation of Radioactive Cesium Contaminated Soil with nano-Fe/Ca/CaO Dispersion Mixture in Dry Condition

    Directory of Open Access Journals (Sweden)

    Mallampati S. R.

    2013-04-01

    Full Text Available Present study, first time we developed a nano-Fe/Ca/CaO dispersion mixture based remediation and volume reduction method of real radioactive cesium contaminated soils. After soil samples treated with 10wt% of nano-Fe/Ca/CaO dispersion mixtures, emitting radiation intensity was reduced from 4.00 μSv/h to 0.95 μSv/h in non-magnetic fraction soils. While, after treatment, about 30wt% magnetic and 70wt% nonmagnetic fraction soils were separated, and it’s condensed radioactive cesium concentration was about 80% and 20%, respectively. By this way, cesium contaminated soil volume can be reduced. These preliminary results appear to be very promising and the simple mixing with the addition of nano-Fe/Ca/CaO may be considered potentially applicable for the remediation and separation of radioactive Cs contaminated soil in dry conditions.

  1. The behaviour of iodine in the compartments soil, plant and air

    International Nuclear Information System (INIS)

    Within the framework of this study, several investigations were carried out into the behaviour of iodine in the soil-plant-air system. Particular attention was given to the mechanisms determining iodine transfer from soil to plant. Measurements of iodine contents in the soil, plants and individual parts of plants were as important an aim of this study as was the identification of factors possibly contributing to an abundant iodine uptake into plants. In view of iodine's role as an element essential to the health of both humans and animals, widely cultured forage crops and useful plants were investigated in this connection. As the relevant literature quotes unusually high contents of the substance for a number of foodstuffs based on plants, these were included in the studies for iodine contents. (orig.)

  2. Investigation of remediation of soil contaminated with diesel fuel using air venting

    International Nuclear Information System (INIS)

    Soil venting is an effective and widely used method to remediate hydrocarbonically contaminated soils. A non-isothermal model, proposed by Lingineni and Dhir (1992) to predict evaporation rates of organic contaminants in an unsaturated non-sorbing soil, was incorporated into a computer code capable of numerically analyzing multi-component diesel fuel. The program accounts for 14 major components of diesel fuel as well as for temperature variation due to evaporation of the contaminant, preheating of the venting air, and heat loss. Experiments to verify the model performance were conducted in a one-dimensional column. Temperature readings from thermocouples located in the test section were recorded during the experiment and the composition of hydrocarbons in the effluent air was also monitored. The effluent gas samples were extracted at the selected times and analyzed with the help of a gas chromatograph. The experimental temperature readings and vapor composition in the extracted samples are in general agreement with the predictions from the computer program. The results show that the diesel components are removed according to their volatility with the higher volatility components being removed first. It is also found that preheating of the venting air can significantly increase the removal rates of the components

  3. Dry/Wet Cycles Change the Activity and Population Dynamics of Methanotrophs in Rice Field Soil

    OpenAIRE

    Ma, Ke; Conrad, Ralf; Lu, Yahai

    2013-01-01

    The methanotrophs in rice field soil are crucial in regulating the emission of methane. Drainage substantially reduces methane emission from rice fields. However, it is poorly understood how drainage affects microbial methane oxidation. Therefore, we analyzed the dynamics of methane oxidation rates, composition (using terminal restriction fragment length polymorphism [T-RFLP]), and abundance (using quantitative PCR [qPCR]) of methanotroph pmoA genes (encoding a subunit of particulate methane ...

  4. Coupled heat and water flow dynamics in dry soils : application to a multilayer waste cover

    OpenAIRE

    Gran Esforzado, Meritxell

    2015-01-01

    Unsaturated flow plays an important role in numerous environmental phenomena. It is complex in arid regions, where liquid water fluxes are small and vapor fluxes become relevant, so that heat, water and solute mass transport are needed to understand evaporation. This thesis aims at gaining insight evaporation and vapor flow mechanisms and the relevance of matric potential, temperature and osmotic gradients. These issues are especially relevant for soil salinization, whose mechanisms are po...

  5. Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

    Directory of Open Access Journals (Sweden)

    M. J. van der Ploeg

    2010-10-01

    Full Text Available Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately −0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed polymer tensiometers (POTs are able to directly measure soil matric potentials until the theoretical wilting point (−1.6 MPa. By minimizing the volume of polymer solution inside the POT while maximizing the ceramic area in contact with that polymer solution, response times drop to acceptable ranges for laboratory and field conditions. Contact with the soil is drastically improved with the use of cone-shaped solid ceramics instead of flat ceramics. The comparison between measured potentials by polymer tensiometers and indirectly obtained potentials with time domain reflectometry highlights the risk of using the latter method at low water contents. By combining POT and time domain reflectometry readings in situ moisture retention curves can be measured over the range permitted by the measurement range of both POT and time domain reflectometry.

  6. Effects of Corn Stover Incorporated in Dry Farmland on Soil Fertility

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-bin; Cai Dian-xiong; ZHANG Jing-qing; GAO Xu-ke

    2001-01-01

    Seven years' field experiments on application of corn stover and/or cattle manure combined with chemical fertilizers were carried out in Shouyang Dryland Farming Experimental Station. Results showed that the increased available N in the plough layer was mainly influenced by the application of cattle manure; the available P was mainly influenced by the application of chemical fertilizer; the available K was mainly influenced by the incorporation of corn stover. The organic matter contents in the soils treated with corn stover or cattle manure were kept in balance under the experimental conditions. Corn yield and water use efficiency were influenced significantly not only by fertilizer N but also by incorporated corn stover. The results suggested that the highest N uptake, yield and water use efficiency could be obtained at rates of 105 kg fertilizer N, 6000 kg corn stover, and 1500 kg cattle manure per hectare. The experiments supplied information on nutrient recycling and use of corn stover as sources of fodder and organic fertilizer for balancing application of organic and inorganic fertilizer, improving soil fertility and increasing crop yield with incorporation of corn stover in soil.

  7. Measurement of effective air diffusion coefficients for trichloroethene in undisturbed soil cores

    Science.gov (United States)

    Bartelt-Hunt, Shannon L.; Smith, James A.

    2002-06-01

    In this study, we measure effective diffusion coefficients for trichloroethene in undisturbed soil samples taken from Picatinny Arsenal, New Jersey. The measured effective diffusion coefficients ranged from 0.0053 to 0.0609 cm 2/s over a range of air-filled porosity of 0.23-0.49. The experimental data were compared to several previously published relations that predict diffusion coefficients as a function of air-filled porosity and porosity. A multiple linear regression analysis was developed to determine if a modification of the exponents in Millington's [Science 130 (1959) 100] relation would better fit the experimental data. The literature relations appeared to generally underpredict the effective diffusion coefficient for the soil cores studied in this work. Inclusion of a particle-size distribution parameter, d10, did not significantly improve the fit of the linear regression equation. The effective diffusion coefficient and porosity data were used to recalculate estimates of diffusive flux through the subsurface made in a previous study performed at the field site. It was determined that the method of calculation used in the previous study resulted in an underprediction of diffusive flux from the subsurface. We conclude that although Millington's [Science 130 (1959) 100] relation works well to predict effective diffusion coefficients in homogeneous soils with relatively uniform particle-size distributions, it may be inaccurate for many natural soils with heterogeneous structure and/or non-uniform particle-size distributions.

  8. The application of in situ air sparging as an innovative soils and ground water remediation technology

    International Nuclear Information System (INIS)

    Vapor extraction (soil venting) has been demonstrated to be a successful and cost-effective remediation technology for removing VOCs from the vadose (unsaturated) zone. However, in many cases, seasonal water table fluctuations, drawdown associated with pump-and-treat remediation techniques, and spills involving dense, non-aqueous phase liquids (DNAPLS) create contaminated soil below the water table. Vapor extraction alone is not considered to be an optimal remediation technology to address this type of contamination. An innovative approach to saturated zone remediation is the use of sparging (injection) wells to inject a hydrocarbon-free gaseous medium (typically air) into the saturated zone below the areas of contamination. The contaminants dissolved in the ground water and sorbed onto soil particles partition into the advective air phase, effectively simulating an in situ air-stripping system. The stripped contaminants are transported in the gas phase to the vadose zone, within the radius of influence of a vapor extraction and vapor treatment system. In situ air sparging is a complex multifluid phase process, which has been applied successfully in Europe since the mid-1980s. To date, site-specific pilot tests have been used to design air-sparging systems. Research is currently underway to develop better engineering design methodologies for the process. Major design parameters to be considered include contaminant type, gas injection pressures and flow rates, site geology, bubble size, injection interval (areal and vertical) and the equipment specifications. Correct design and operation of this technology has been demonstrated to achieve ground water cleanup of VOC contamination to low part-per-billion levels

  9. Numerical modeling studies on the alternately pulsed infiltration and subsequent evaporation of water in a dry high desert alluvial soil

    International Nuclear Information System (INIS)

    The concept of no liquid-phase migration of low-level radionuclides is extremely important for the U.S. Department of Energy, Nevada Operations Office (USDOE/NV) Low-Level Radioactive Waste Management Sites (RWMS) in Areas 3 and 5 of the Nevada Test Site (NTS). Each site location is situated in an area known for its dry conditions. A series of computer modeling problems were set up to study the effects of pulsing the desert surface with large amounts of water, followed by intense evaporative conditions. The pulsed-water scenarios were run using an in-house model, named open-quotes ODRECHB,close quotes which is briefly described. ODRECHB is particularly adapted to model the dry desert alluvium and extreme evaporative conditions found at NTS. Comparable results were obtained using the well known Battelle NW code open-quotes UNSAT-H 2.0,close quotes by Fayer and Jones. The realistic-to-overly conservative water applications to a bare soil surface did not cause water to infiltrate below ten meters. The results are shown on the accompanying video tape

  10. Georeferenced database on soil and air climate parameters of Russia and its cartographic implications

    Science.gov (United States)

    Alyabina, Irina; Reshotkin, Oleg; Konyushkov, Dmitry; Khudyakov, Oleg

    2014-05-01

    Many theoretical and applied problems related to the assessment of ecosystem response to climate changes imply simultaneous analysis of data on air and soil climate. In particular, soil temperature is a very important characteristic allowing us to judge sensitivity of ecosystems to climatic fluctuations and anthropogenic impacts. It is also of great importance for predicting the functioning of terrestrial biocenoses, geocryological and engineering conditions of the territory, etc. The vast territory of Russia is characterized by the great diversity of soil climatic conditions and by differently directed tendencies of their recent changes. A combined study of the spatial and temporal changes in the parameters of soil and atmospheric climates of Russia and their cartographic modeling are of great interest. Russia has a well-developed network of weather stations, at which measurements of soil temperatures at standard depths have been performed using the same methods for more than a century. The analysis of these data with the use of geographic information systems seems to be promising. For this purpose, a georeferenced database on the parameters of soil and atmospheric climate is being developed. Such a database in the GIS environment makes it possible to develop a system of cartographic models of the climate of Russian soils, including data on the climatic norm (1960-1990) and on its changes in the recent decades. This system will be used for assessing soil climatic conditions in the subjects of the Russian Federation and in separate soil-geographic provinces. A series of small-scale preliminary maps of soil temperature parameters was included in the National Soil Atlas of the Russian Federation (2011). These maps indicate that the mean annual soil temperature in Russia varies from -14.5 to +15.2ºC, and the accumulated daily temperatures >10ºC increase in the southward direction from 0 to 4800ºC (degree-days). The duration of the period with soil temperatures >10

  11. Nodulation, dry matter production and N2 fixation by fababean and chickpea as affected by soil moisture and potassium fertilizer

    International Nuclear Information System (INIS)

    The impact of three rates of K-fertilizer (0, 75, and 150 kg K2O/ha)on nodulation, dry matter production and N2 fixation by fababean (Vicia faba L.) and chickpea (Cirer arietinum L.) was evaluated in a pot experiment. The plants were subjected to three soil moisture regimes (low, 45-50%; moderate, 55-60% and high 75-80% of field capacity). 15N-isotope dilution method was employed to evaluate N2 fixation using a non-fixing chickpea genotype as a reference crop. Water restriction drastically affected dry matter production, nodulation and N2 fixation by both plant species. The negative effect of water stress on %N2 fixed was more prominent in chickpea (11-58%) than in fababean (68-81%) under low and high % of field capacity, respectively. Plant species differed in their response to K-fertilizer as a mean to enhance growth and overcome the stress conditions. The higher level of K fertilizer increased both dry matter production and total N2 fixed in fababean, but did not have any impact on chickpea. %N2 fixed, however, appeared to be unaffected by K fertilizer as a mean of alleviating drought stress in both plant species. Therefore, it appears that, under the experimental conditions, the beneficial effect of potassium on water-stressed fababean resulted from stimulation the growth rather than improving the N2-fixation efficiency. However, under well-watered plants, a high requirement of the symbiotic system to potassium is needed to ensure and optimal growth and N2-fixation. (author)

  12. Effect of process parameters on energy performance of spray drying with exhaust air heat recovery for production of high value particles

    International Nuclear Information System (INIS)

    Highlights: • We study heat recovery from spray dryer using air-to-air heat exchanger. • We examine dryer energy performance using advanced mathematical model. • We use the response surface methodology to study the effect of process parameters. • Energy efficiency up to 43.3% is obtained at high flow rate of dilute slurry. • Energy saving up to 52.4% is obtained at high drying air temperature. - Abstract: Spray drying process has been widely used in various industries for many decades for production of numerous materials. This paper explores the energy performance of an industrial scale spray dryer equipped with an exhaust air heat recovery system for production of high value particles. Energy efficiency and energy saving were calculated using a comprehensive mathematical model of spray drying. The response surface methodology (RSM) was utilized to study the effect of process parameters on energy performance using a space-filling design. The meta model equations were formulated employing the well-fitted response surface equations with adjusted R2 larger than 0.995. The energy efficiency as high as 43.3% was obtained at high flow rate of dilute slurry, while the highest energy saving of 52.4% was found by combination of positive effect of drying air temperature and negative effect of slurry mass flow rate. The utilization of efficient air-to-air heat exchanger leads to an increase in energy efficiency and energy savings. The detailed temperature and vapor concentration profiles obtained with the model are also valuable in determining final product quality when spray dryer is operated at energy efficient conditions

  13. Microbial community dynamics and methane, carbon dioxide, oxygen, and nitrous oxide concentrations in upland forest and riparian soils across a seasonal gradient of fully saturated soils to completely dried soils

    Science.gov (United States)

    Jones, R. T.; McGlynn, B. L.; McDermott, T.; Dore, J. E.

    2015-12-01

    Gas concentrations (CH4, CO2, N2O, and O2), soil properties (soil water content and pH), and microbial community composition were measured from soils at 32 sites across the Stringer Creek Watershed in the Tenderfoot Creek Experimental Forest 7 times between June 3, 2013 and September 20, 2013. Soils were fully saturated during the initial sampling period and dried down over the course of the summer. Soils and gas were sampled from 5cm and 20cm at each site and also at 50cm at eight riparian sites. In total, 496 individual soil samples were collected. Soil moisture ranged from 3.7% to fully saturated; soil pH ranged from 3.60 to 6.68. Methane concentrations in soils ranged from 0.426 ppm to 218 ppm; Carbon dioxide concentrations ranged from 550 ppm to 42,990 ppm; Nitrous oxide concentrations ranged from 0.220 ppm to 2.111 ppm; Oxygen concentrations ranged from 10.2% to 21.5%. Soil microbial communities were characterized by DNA sequences covering the V4 region of the 16S rRNA gene. DNA sequences were generated (~30,000,000 sequences) from the 496 soil samples using the Illumina MiSeq platform. Operational Taxonomic Units were generated using USEARCH, and representative sequences were taxonomically classified according the Ribosomal Database Project's taxonomy scheme. Analysis of similarity revealed that microbial communities found within a landscape type (high upland forest, low upland forest, riparian) were more similar than among landscape types (R = 0.600; ptests to determine how community structure co-varies with the soil environment and gas concentrations. All variables measured significantly co-varied with microbial community membership (pH: R = 0.712, p < 0.001; CO2: R = 0.578, p < 0.001; O2: R = 0.517, p < 0.001; Soil moisture: R = 0.408, p < 0.001; N2O: R = 0.218, p = 0.003; CH4: R = 0.195, p = 0.008). Despite the rather low co-variation between methane concentrations and microbial community composition, relative abundances of methanotrophic and

  14. Effect of Harvest of Air Relative Humidity on Water and Heat Transfer in Soil With Crops Under Arid Climatic Conditions

    Directory of Open Access Journals (Sweden)

    El Khadir LAKHAL

    2015-05-01

    Full Text Available In this work, the main objective is to analyze the effect of the harvest of air relative humidity on soil temperature, soil water storage and evaporation. An experiment work was conducted in order to evaluate the quantity of soil water adsorbed by harvesting of relative air humidity. This experimental work was conducted on hilly areas with various hypsographic and microclimatic conditions greatly affecting daily fluctuations of air humidity and soil characteristics. The metrological data needed by SISPAT model were obtained by using a Campbell Scientific equipments Station recorder on data loggers every half hour. A numerical model based on SiSPAT (Système d’Interaction Sol Plante Atmosphère formulation is adopted. The general equations of the proposed model are based on heat and mass transfer in the soil, atmosphere and plant system. This study shows that Soil Water Adsorption (SWA induce an increasing in the total evaporation and in soil water storage especially on the upper layers. The effect of Soil Water Adsorption on soil temperature appears for the first layers of soil and become absent in the profound zone because the vapour condensation phenomenon is very important at night for the first layers.

  15. Evaluation of short-term tracer fluctuations in groundwater and soil air in a two year study

    Science.gov (United States)

    Jenner, Florian; Mayer, Simon; Aeschbach, Werner; Weissbach, Therese

    2016-04-01

    The application of gas tracers like noble gases (NGs), SF6 or CFCs in groundwater studies such as paleo temperature determination requires a detailed understanding of the dynamics of reactive and inert gases in the soil air with which the infiltrating water equilibrates. Due to microbial gas consumption and production, NG partial pressures in soil air can deviate from atmospheric air, an effect that could bias noble gas temperatures estimates if not taken into account. So far, such an impact on NG contents in groundwater has not been directly demonstrated. We provide the first long-term study of the above mentioned gas tracers and physical parameters in both the saturated and unsaturated soil zone, sampled continuously for more than two years near Mannheim (Germany). NG partial pressures in soil air correlate with soil moisture and the sum value of O2+CO2, with a maximal significant enhancement of 3-6% with respect to atmospheric air during summer time. Observed seasonal fluctuations result in a mass dependent fractionation of NGs in soil air. Concentrations of SF6 and CFCs in soil air are determined by corresponding fluctuations in local atmospheric air, caused by industrial emissions. Arising concentration peaks are damped with increasing soil depth. Shallow groundwater shows short-term NG fluctuations which are smoothed within a few meters below the water table. A correlation between NG contents of soil air and of groundwater is observable during strong recharge events. However, there is no evidence for a permanent influence of seasonal variations of soil air composition on shallow groundwater. Fluctuating NG contents in shallow groundwater are rather determined by variations of soil temperature and water table level. Our data gives evidence for a further temperature driven equilibration of groundwater with entrapped air bubbles within the topmost saturated zone, which permanently occurs even some years after recharge. Local subsurface temperature fluctuations

  16. The effects of rice canopy on the air-soil exchange of polycyclic aromatic hydrocarbons and organochlorine pesticides using paired passive air samplers.

    Science.gov (United States)

    Wang, Yan; Wang, Shaorui; Luo, Chunling; Li, Jun; Ming, Lili; Zhang, Gan; Li, Xiangdong

    2015-05-01

    The rice canopy in paddy fields can influence the air-soil exchange of organic chemicals. We used paired passive air samplers to assess the exchange of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs) in a paddy field, South China. Levels of OCPs and light PAHs were generally higher under the canopy than above it. We found that the rice canopy can physically obstruct the evaporation of most OCPs and light PAHs, and can also act as a barrier to the gaseous deposition of p,p'-DDT and heavy PAHs. Paddy fields can behave as a secondary source of OCPs and light PAHs. The homolog patterns of these two types of chemical varied slightly between the air below and above the rice canopy, implying contributions of different sources. Paired passive air samplers can be used effectively to assess the in situ air-soil exchange of PAHs and OCPs in subtropical paddy fields. PMID:25686886

  17. Gravel washing demonstration system and reducing the contaminated soil by BAT (Blend Air Tornado pump)

    International Nuclear Information System (INIS)

    Gravel washing system is composed of Blend Air Tornado pump (BAT), gravel classification and muddy water purification equipments. Gravel contaminated by radioactive cesium, pure water and air are mixed in BAT. This process will wash the contaminated gravel and reduce its radioactivity quickly. BAT is operated under appropriate water pressure and air/water/solid gravel ratio. After washing the gravel, it is classified by grain gravel classification equipment and the muddy waste water is purified by cohesive material process. This process is simple and reasonable gravel washing system. Improvement of the existing technology and the maintenance management in easy operation and a small number of people are possible for the system. The system is demonstrated to be the high efficiency decontamination technology of radioactive cesium on soils such as gravel with energy saving system which does not give the load on the environment. (author)

  18. Patterns and possible mechanisms of soil CO2 uptake in sandy soil.

    Science.gov (United States)

    Fa, Ke-Yu; Zhang, Yu-Qing; Wu, Bin; Qin, Shu-Gao; Liu, Zhen; She, Wei-Wei

    2016-02-15

    It has been reported that soils in drylands can absorb CO2, although the patterns and mechanisms of such a process remain under debate. To address this, we investigated the relationships between soil CO2 flux and meteorological factors and soil properties in Northwest China to reveal the reasons for "anomalous" soil CO2 flux in a desert ecosystem. Soil CO2 flux increased significantly and exponentially with surficial turbulence at the diel scale under dry conditions (Pair pressure (PLaw indicated that soil water content was insufficient to dissolve the absorbed CO2 in dry conditions, but was sufficient in wet conditions. The concentration of soil HCO3(-) in the morning was higher than in the evening in dry conditions, but this pattern was reversed in wet conditions. These results imply that CO2 outgassing induced by turbulence, expansion of soil air, CO2 effusion from soil water, and carbonate precipitation during daytime can explain the abiotic diurnal CO2 release. Moreover, CO2 pumping from the atmosphere into the soil, caused mainly by carbonate dissolution, can account for nocturnal CO2 absorption in dry conditions. The abiotic soil CO2 flux pattern (CO2 absorption throughout the diel cycle) in wet conditions can be attributed to downward mass flow of soil CO2 and intensified soil air shrinkage, CO2 dissolving in soil water, and carbonate dissolution. These results provide a basis for determining the location of abiotic fixed carbon within soils in desert ecosystems. PMID:26674687

  19. 圣女果分段式变温变湿热风干燥特性%Dried characteristics of cherry tomatoes using temperature and humidity by stages changed hot-air drying method

    Institute of Scientific and Technical Information of China (English)

    王庆惠; 李忠新; 杨劲松; 谢龙; 张世湘; 高振江

    2014-01-01

    Cherry tomato decays easily. Generally, it can be preserved only for 5-7days under normal pressure and temperature. The dehydration of cherry tomatoes into dried or preserved fruits can prolong their shelf life and enrich the market of the fruit. Currently, cherry tomatoes is dehydrated through natural drying. The advantage of this method is simple, and low cost. But the drying time is long and is affected by the climate and sanitary conditions. The product quality is difficult to control. In order to shorten the drying time and prevent mildew, cherry tomatoes are often soaked or sprayed with the alkaline solution. These chemicals are bad for our health. Multi-stage temperature-and-humidity drying is conducted through the material drying characteristics. This method can speed up the drying rate, improve drying quality, and reduce energy consumption. It has been successfully applied for apricot,lyceum barbarum, grapes and other materials. In this study, internal recycling hot-air drying technology was employed for the drying of cherry tomatoes. The effects of drying temperatures, humidity, drying stages and slicing forms on the drying characteristics and the appearance quality of the cherry tomatoes were investigated. Each experiment was composed of four drying stages. The drying temperatures were fixed, the humidity of the environment was changed in processⅠ,Ⅱ andⅢ. The drying temperature was low, the humidity was high at the beginning of processⅣ. Gradually, the temperature was raised, the humidity was reduced. At the end of the process, the drying temperature was higher, the humidity was lower compared with their values at the beginning. The experimental results indicated that pre-heated and falling rate periods exist during the drying of cherry tomato. Previous studies only shown falling rate period. The increase in temperature and humidity has bad effects on the nutrition, color and the appearance quality of cherry tomato. Even though cherry tomato can

  20. Pan-Arctic linkages between snow accumulation and growing-season air temperature, soil moisture and vegetation

    OpenAIRE

    K. A. Luus; Gel, Y.; J. C. Lin; Kelly, R. E. J.; C. R. Duguay

    2013-01-01

    Arctic field studies have indicated that the air temperature, soil moisture and vegetation at a site influence the quantity of snow accumulated, and that snow accumulation can alter growing-season soil moisture and vegetation. Climate change is predicted to bring about warmer air temperatures, greater snow accumulation and northward movements of the shrub and tree lines. Understanding the responses of northern environments to changes in s...

  1. Drivers of soil drying in the Czech Republic between 1961 and 2012

    Czech Academy of Sciences Publication Activity Database

    Trnka, Miroslav; Brázdil, Rudolf; Balek, J.; Semerádová, Daniela; Hlavinka, Petr; Možný, M.; Štěpánek, Petr; Dobrovolný, Petr; Zahradníček, Pavel; Dubrovský, Martin; Eitzinger, Josef; Fuchs, B.; Svoboda, M.; Hayes, M.; Žalud, Zdeněk

    2015-01-01

    Roč. 35, č. 9 (2015), s. 2664-2675. ISSN 0899-8418 R&D Projects: GA MŠk(CZ) LD13030; GA MŠk(CZ) EE2.3.20.0248; GA MŠk(CZ) EE2.3.20.0256; GA ČR GA13-04291S; GA MZe QJ1310123 Institutional support: RVO:67179843 ; RVO:68378289 Keywords : pan evaporation * soil moisture * reference evapotranspiration * drought climatology * water balance * observed climate change Subject RIV: EH - Ecology, Behaviour Impact factor: 3.157, year: 2014

  2. Soil erosion and causative factors at Vandenberg Air Force Base, California

    Science.gov (United States)

    Butterworth, Joel B.

    1988-01-01

    Areas of significant soil erosion and unvegetated road cuts were identified and mapped for Vandenberg Air Force Base. One hundred forty-two eroded areas (most greater than 1.2 ha) and 51 road cuts were identified from recent color infrared aerial photography and ground truthed to determine the severity and causes of erosion. Comparison of the present eroded condition of soils (as shown in the 1986 photography) with that in historical aerial photography indicates that most erosion on the base took place prior to 1928. However, at several sites accelerated rates of erosion and sedimentation may be occurring as soils and parent materials are eroded vertically. The most conspicuous erosion is in the northern part of the base, where severe gully, sheet, and mass movement erosion have occurred in soils and in various sedimentary rocks. Past cultivation practices, compounded by highly erodible soils prone to subsurface piping, are probably the main causes. Improper range management practices following cultivation may have also increased runoff and erosion. Aerial photography from 1986 shows that no appreciable headward erosion or gully sidewall collapse have occurred in this area since 1928.

  3. Evaluation of the response of tritium-in-air instrumentation to HT in dry and humid conditions and to HTO vapor

    International Nuclear Information System (INIS)

    Nuclear plant operators (power generation, decommissioning and reprocessing operations) are required to monitor releases of tritium species for regulatory compliance and radiation protection purposes. Tritium monitoring is performed using tritium-in-air gas monitoring instrumentation based either on flow-through ion chambers or proportional counting systems. Tritium-in-air monitors are typically calibrated in dry conditions but in service may operate at elevated levels of relative humidity. The NPL (National Physical Laboratory) radioactive gas-in-air calibration system has been used to study the effect of humidity on the response to tritium of two tritium-in-air ion chamber based monitors and one proportional counting system which uses a P10/air gas mixture. The response of these instruments to HTO vapour has also been evaluated. In each case, instrument responses were obtained for HT in dry conditions (relative humidity (RH) about 2%), HT in 45% RH, and finally HTO at 45% RH. Instrumentation response to HT in humid conditions has been found to slightly exceed that in dry conditions. (authors)

  4. The correlations between Radon in soil gas and its exhalation and concentration in air in the southern part of Syria

    International Nuclear Information System (INIS)

    The aim of this work is to measure the concentration of the radon (222Rn) in soil air, 222Rn exhalation from soil and 222Rn in outdoor air which may have great influence on 222Rn levels in houses. 222Ra activity concentrations were also determined in soil samples. The studied areas are located in southern part of Syria. The common bed rock of this area is black and massive granite which are poor in uranium content [Jubeli Y.M., 1990. Uranium exploration in Syria. Internal Technical Report, vol. 1 (in English), vol. 2 (in Arabic), SAEC, Damascus; Technoexport (USSR), 1966. In: Ponikarov (Ed.), The Geological Map of Syria Scale: 1:200.000, Ministry of Industry, Damascus, Syria]. Results showed that the maximum measurement in all areas was 32500Bqm-3 in soil air with an exhalation rate of 9Bqm-2s-1 in Darra region and 66.43Bqm-3 of radon in open air, with 77Bqkg-1 of radium content in soil (Damascus suburb). In addition, correlations between Rn in soil and exhalation of Radon from soil and radon in houses were found in some areas (Sweda and Darra), while, no correlations were found in other studied areas. Moreover, no correlation between radon in houses and radon measurements in soil and in outdoors were found. This was attributed to the methodology used and the influence of building design and inhabitants behavior

  5. Thermal diffusion: An important aspect in studies of static air columns such as firn air, sand dunes and soil air

    International Nuclear Information System (INIS)

    Thermal diffusion induced by temperature gradients is an additional part of diffusional processes besides the ordinary or concentration diffusion. Heavier molecules normally migrate to the colder end of a static column hence leading to a slight separation in composition. Thermal diffusion can be most easily traced by isotopic ratios which are hardly exposed to changes in other processes, such as nitrogen and argon isotope ratios. Since only a limited number of thermal diffusion factors is measured up to now, it is important to have an idea how large they could be to check whether thermal diffusion effects have to be considered in interpreting corresponding isotope or elemental ratios. The Lennard-Jones (13,7) model is quite successful in estimating these factors as seen by comparison between measured and calculated values. However, there are still large uncertainties, particularly in assigning a correct critical temperature to a complex mixture such as air when considering only a ratio of two air components. It seems that the noble gas ratio Ne/Ar would be ideal to separate the gravitational enrichment from thermal diffusion due to a rather high thermal diffusion factor. However, as helium, neon has a high permeability in ice which strongly hampers this advantage. Therefore other noble gas ratios such as Ar/Kr and/or Ar/Xe are favoured for such experiments. For ice core studies the temporal variation of the thermal diffusion fractionation carries a large potential for reconstructing temperature variations over long time periods as well as synchronising gas and ice records with high precision based on very precise estimates of gas-ice age differences. (author)

  6. Deep rooting plants influence on soil hydraulic properties and air conductivity over time

    Science.gov (United States)

    Uteau, Daniel; Peth, Stephan; Diercks, Charlotte; Pagenkemper, Sebastian; Horn, Rainer

    2014-05-01

    Crop sequences are commonly suggested as an alternative to improve subsoil structure. A well structured soil can be characterized by enhanced transport properties. Our main hypothesis was, that different root systems can modify the soil's macro/mesopore network if enough cultivation time is given. We analyzed the influence of three crops with either shallower roots (Festuca arundinacea, fescue) or taproots (Cichorium intybus, chicory and Medicago sativa, alfalfa). The crops where cultivated on a Haplic Luvisol near Bonn (Germany) for one, two or three years. Undisturbed soil cores were taken for measurement of unsaturated hydraulic conductivity and air permeability. The unsaturated conductivity was measured using the evaporation method, monitoring the water content and tension at two depths of each undisturbed soil core. The van Genuchten-Mualem model (1991) was fitted to the measured data. Air permeability was measured in a permeameter with constant flow at low pressure gradient. The measurements were repeated at -1, -3, -6, -15, -30 and -50 kPa matric tension and the model of Ball et al. (1988) was used to describe permeability as function of matric tension. Furthermore, the cores equilibrated at -15 kPa matric tension were scanned with X-Ray computer tomography. By means of 3D image analysis, geometrical features as pore size distribution, tortuosity and connectivity of the pore network was analyzed. The measurements showed an increased unsaturated hydraulic conductivity associated to coarser pores at the taprooted cultivations. A enhanced pore system (related to shrink-swell processes) under alfalfa was observed in both transport measurements and was confirmed by the 3D image analysis. This highly functional pore system (consisting mainly of root paths, earthworm channels and shrinking cracks) was clearly visible below the 75 cm of depth and differentiated significantly from the other two treatments only after three years of cultivation, which shows the time

  7. Three years of greenhouse gas column-averaged dry air mole fractions retrieved from satellite – Part 1: Carbon dioxide

    Directory of Open Access Journals (Sweden)

    O. Schneising

    2008-07-01

    Full Text Available Carbon dioxide (CO2 and methane (CH4 are the two most important anthropogenic greenhouse gases. SCIAMACHY on ENVISAT is the first satellite instrument whose measurements are sensitive to concentration changes of the two gases at all altitude levels down to the Earth's surface where the source/sink signals are largest. We have processed three years (2003–2005 of SCIAMACHY near-infrared nadir measurements to simultaneously retrieve vertical columns of CO2 (from the 1.58 μm absorption band, CH4 (1.66 μm and oxygen (O2 A-band at 0.76 μm using the scientific retrieval algorithm WFM-DOAS. We show that the latest version of WFM-DOAS, version 1.0, which is used for this study, has been significantly improved with respect to its accuracy compared to the previous versions while essentially maintaining its high processing speed (~1 min per orbit, corresponding to ~6000 single measurements, and per gas on a standard PC. The greenhouse gas columns are converted to dry air column-averaged mole fractions, denoted XCO2 (in ppm and XCH4 (in ppb, by dividing the greenhouse gas columns by simultaneously retrieved dry air columns. For XCO2 dry air columns are obtained from the retrieved O2 columns. For XCH4 dry air columns are obtained from the retrieved CO2 columns because of better cancellation of light path related errors compared to using O2 columns retrieved from the spectrally distant O2 A-band. Here we focus on a discussion of the XCO2 data set. The XCH4 data set is discussed in a separate paper (Part 2. In order to assess the quality of the retrieved XCO2 we present comparisons with Fourier Transform Spectroscopy (FTS XCO2 measurements at two northern hemispheric mid-latitude ground stations. To assess the quality globally, we present detailed comparisons with

  8. Dragonfly (insecta: odonata) diversity in two use of soils in a tropical dry forest

    International Nuclear Information System (INIS)

    Dragonfly diversity was estimated in the Agricultural Center Cotove (Santafe de Antioquia-Colombia). Active capture using an entomological net was used. Each transect was located perpendicular to the water body, for a length of approximately 200 m and a lateral extension of 8 m. Twenty Odonata species were registered, from 5 families and 15 genus. Libellulidae showed the biggest abundance and richness, with 65 specimens that represent 53.7% of the total abundance, and 12 species that represent 60% of the registered community. The diversity was high in the forest in reference at crop; however, the low abundances register highlight the need for greater sampling effort in cultivating, for a better estimate of ? diversity; the diversity was of 12 species and the complementary index was of 0.6, it indicates that the Odonata's fauna is characteristic and distinctive for each use of soil.

  9. The ecological dichotomy of ammonia-oxidizing archaea and bacteria in the hyper-arid soils of the Antarctic Dry Valleys

    Directory of Open Access Journals (Sweden)

    Catarina Maria Magalhães

    2014-09-01

    Full Text Available The McMurdo Dry Valleys of Antarctica are considered to be one of the most physically and chemically extreme terrestrial environments on the Earth. However, little is known about the organisms involved in nitrogen transformations in these environments. In this study, we investigated the diversity and abundance of ammonia-oxidizing archaea (AOA and bacteria (AOB in four McMurdo Dry Valleys with highly variable soil geochemical properties and climatic conditions: Miers Valley, Upper Wright Valley, Beacon Valley and Battleship Promontory. The bacterial communities of these four Dry Valleys have been examined previously, and the results suggested that the extremely localized bacterial diversities are likely driven by the disparate physicochemical conditions associated with these locations. Here we showed that AOB and AOA amoA gene diversity was generally low; only four AOA and three AOB operational taxonomic units (OTUs were identified from a total of 420 AOA and AOB amoA clones. Quantitative PCR analysis of amoA genes revealed clear differences in the relative abundances of AOA and AOB amoA genes among samples from the four Dry Valleys. Although AOB amoA gene dominated the ammonia-oxidizing community in soils from Miers Valley and Battleship Promontory, AOA amoA gene were more abundant in samples from Upper Wright and Beacon Valleys, where the environmental conditions are considerably harsher (e.g., extremely low soil C/N ratios and much higher soil electrical conductivity. Correlations between environmental variables and amoA genes copy numbers, as examined by redundancy analysis (RDA, revealed that higher AOA/AOB ratios were closely related to soils with high salts and Cu contents and low pH. Our findings hint at a dichotomized distribution of AOA and AOB within the Dry Valleys, potentially driven by environmental constraints.

  10. Plants + soil/wetland microbes: Food crop systems that also clean air and water

    Science.gov (United States)

    Nelson, Mark; Wolverton, B. C.

    2011-02-01

    The limitations that will govern bioregenerative life support applications in space, especially volume and weight, make multi-purpose systems advantageous. This paper outlines two systems which utilize plants and associated microbial communities of root or growth medium to both produce food crops and clean air and water. Underlying these approaches are the large numbers and metabolic diversity of microbes associated with roots and found in either soil or other suitable growth media. Biogeochemical cycles have microbial links and the ability of microbes to metabolize virtually all trace gases, whether of technogenic or biogenic origin, has long been established. Wetland plants and the rootzone microbes of wetland soils/media also been extensively researched for their ability to purify wastewaters of a great number of potential water pollutants, from nutrients like N and P, to heavy metals and a range of complex industrial pollutants. There is a growing body of research on the ability of higher plants to purify air and water. Associated benefits of these approaches is that by utilizing natural ecological processes, the cleansing of air and water can be done with little or no energy inputs. Soil and rootzone microorganisms respond to changing pollutant types by an increase of the types of organisms with the capacity to use these compounds. Thus living systems have an adaptive capacity as long as the starting populations are sufficiently diverse. Tightly sealed environments, from office buildings to spacecraft, can have hundreds or even thousands of potential air pollutants, depending on the materials and equipment enclosed. Human waste products carry a plethora of microbes which are readily used in the process of converting its organic load to forms that can be utilized by green plants. Having endogenous means of responding to changing air and water quality conditions represents safety factors as these systems operate without the need for human intervention. We review