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Sample records for alentejo soils surface

  1. Degradation of metalaxyl and folpet by filamentous fungi isolated from Portuguese (Alentejo) vineyard soils.

    PubMed

    Martins, M Rosário; Pereira, Pablo; Lima, Nelson; Cruz-Morais, Júlio

    2013-07-01

    Degradation of xenobiotics by microbial populations is a potential method to enhance the effectiveness of ex situ or in situ bioremediation. The purpose of this study was to evaluate the impact of repeated metalaxyl and folpet treatments on soil microbial communities and to select soil fungal strains able to degrade these fungicides. Results showed enhanced degradation of metalaxyl and folpet in vineyards soils submitted to repeated treatments with these fungicides. Indeed, the greatest degradation ability was observed in vineyard soil samples submitted to greater numbers of treatments. Respiration activities, as determined in the presence of selective antibiotics in soil suspensions amended with metalaxyl and folpet, showed that the fungal population was the microbiota community most active in the degradation process. Batch cultures performed with a progressive increase of fungicide concentrations allowed the selection of five tolerant fungal strains: Penicillium sp. 1 and Penicillium sp. 2, mycelia sterila 1 and 3, and Rhizopus stolonifer. Among these strains, mycelium sterila 3 and R. stolonifer presented only in vineyard soils treated with repeated application of these fungicides and showed tolerance >1,000 mg l(-1) against commercial formulations of metalaxyl (10 %) plus folpet (40 %). Using specific methods for inducing sporulation, mycelium sterila 3 was identified as Gongronella sp. Because this fungus is rare, it was compared using csM13-polymerase chain reaction (PCR) with the two known species, Gongronella butleri and G. lacrispora. The high tolerance to metalaxyl and folpet shown by Gongronella sp. and R. stolonifer might be correlated with their degradation ability. Our results point out that selected strains have potential for the bioremediation of metalaxyl and folpet in polluted soil sites.

  2. Telemedicine in Alentejo

    PubMed Central

    Bayer, Steffen; Gonçalves, Luís; Barlow, James

    2014-01-01

    Abstract Alentejo covers a third of Portugal, yet it is home to only 5% of the population. Residents of the region are poorer, older, and less educated than the rest of the country. There is a shortage of physicians in several specialties. The low population density, a concentration of specialized services, and a poor public transportation network all create barriers to access. Telemedicine was introduced in 1998 to help address these challenges. In this article, we provide an overview of the program and its current status, focusing on infrastructure, services, and activity volume. We also discuss the impact the program has had from the perspectives of patients and healthcare professionals. From 1998 to 2011, there were 132,546 episodes of service using telemedicine, including real-time teleconsultations, teleradiology, teleultrasound, and telepathology. At present, the network includes 20 primary care units and five hospitals, covering almost 30,000 km2 and 500,000 people. Units have high-resolution videoconferencing equipment, access to patients' clinical records, an image archive, and peripherals, such as electronic dermatoscopes and phonendoscopes. Teleconsultations are available in 15 medical specialties and areas, ranging from neurology to pediatric surgery. In 2008, regional health authorities started a tele-education program, and by the end of 2011, 876 healthcare professionals, across 52 locations, had participated in remote learning sessions. More than a decade since telemedicine was introduced in Alentejo, it is now an integral part of everyday service provision. A comprehensive assessment of the costs and consequences of the program is currently underway. PMID:24180419

  3. Minerals and trace elements in silcretes of the Sado basin (Alentejo, southern Portugal) and implications for silcrete formation

    NASA Astrophysics Data System (ADS)

    Sauer, Daniela; Kullmann, Sarah; Zarei, Mehdi; Stahr, Karl

    2014-05-01

    Soils in the eastern part of the Sado basin (southern Portugal) are often characterized by massive cementations caused by silica. The thickness and massive character of these silcretes led to the hypothesis that accumulation of silica took place not only vertically within a soil profile, but also by enrichment through lateral water and element flow into the Sado basin. The aims of the study reported here were: 1) to characterize the cementing agent with regard to its mineralogy; 2) to test the hypothesis that silification was enhanced through lateral silica transport from the adjacent Alto Alentejo into the Sado basin. Aim 1) was achieved by scratching silica coatings from ped surfaces of the silicified soil horizons and cleaning them manually in the lab under a binocular microscope. After careful smashing with a mortar, density separation by sodium polytungstate solution was applied to remove any remaining mineral grains from the silica samples. The cleaned silica samples were then subjected to XRD and SEM in combination with EDS. Aim 2) was attained by using trace element contents of predominant rock types of the Alto Alentejo and of the silcretes in the Sado basin for identifying lateral pathways of water and silica in the landscape. Ten rock samples from the assumed source area of silica were combusted by fusion melt, and their contents of Ba, Co, Cs, Nb, Pb, Rb, Sr, Y and Zr were analyzed by ICP-MS. The same elements were analyzed in NaOH extracts of the cemented soil horizons in the Sado basin. The X-ray diagrams of the silica coatings show the expected broad hump of amorphous silica. In addition, quartz, kaolinite, and surprisingly high amounts of halloysite are identified, the latter reflecting conditions of intensive weathering and pedogenesis during the formation of the silica coatings. This intensive soil formation and hence silification most likely took place during Pliocene. Greater age is impossible, because the silification took place in Pliocene

  4. Estimation of Surface Soil Moisture Using Fractal

    NASA Astrophysics Data System (ADS)

    Chen, Yen Chang; He, Chun Hsuan

    2016-04-01

    This study establishes the relationship between surface soil moisture and fractal dimension. The surface soil moisture is one of important factors in the hydrological cycle of surface evaporation. It could be used in many fields, such as reservoir management, early drought warning systems, irrigation scheduling and management, and crop yield estimations. Soil surface cracks due to dryness can be used to describe drought conditions. Soil cracking phenomenon and moisture have a certain relationship, thus this study makes used the fractal theory to interpret the soil moisture represented by soil cracks. The fractal dimension of surface soil cracking is a measure of the surface soil moisture. Therefore fractal dimensions can also be used to indicate how dry of the surface soil is. This study used the sediment in the Shimen Reservoir to establish the fractal dimension and soil moisture relation. The soil cracking is created under the control of temperature and thickness of surface soil layers. The results show the increase in fractal dimensions is accompanied by a decreases in surface soil moisture. However the fractal dimensions will approach a constant even the soil moisture continually decreases. The sigmoid function is used to fit the relation of fractal dimensions and surface soil moistures. The proposed method can be successfully applied to estimate surface soil moisture. Only a photo taken from the field is needed and is sufficient to provide the fractal dimension. Consequently, the surface soil moisture can be estimated quickly and accurately.

  5. Uranium in surface soils: an easy-and-quick assay combining X-ray diffraction and fluorescence qualitative data

    NASA Astrophysics Data System (ADS)

    Figueiredo, M. O.; Silva, T. P.; Batista, M. J.; Leote, J.; Ferreira, M. L.; Limpo, V.

    2009-04-01

    Portugal has been a uranium-producer since the beginning of the last century. The uranium-rich area of Alto Alentejo, East-central Portugal, was identified more than fifty years ago [1]. Almost all the uranium-bearing mineralization occurs in schistose rocks of the contact metamorphic aureole produced by intrusion of the Hercynian monzonitic granite of Alto Alentejo into the pre-Ordovitian schist-greywacke complex forming deposits of vein and dissemination type. The Nisa uranium-reservoir, situated at the sharp border of a large and arch shaped granite pluton, was identified in 1957 [2] but its exploitation was considered economically impracticable until recently. However, its existence and the accumulated detritus of these prospect efforts are a concern for local populations [3]. A study of the near-surface soils close to the Nisa reservoir was therefore undertaken to assess the uranium retention by adsorption on clay components under the form of uranyl ions, [UO2]2+ [4-6] and its eventual release into the aquifer groundwater. As an attempt to very quickly appraise the presence of uranium in as-collected near-surface sediment samples a combination of laboratory X-ray techniques was designed: X-ray diffraction (XRD) to identify the mineral phases and roughly estimate its relative proportion plus X-ray fluorescence spectrometry in wavelength dispersive mode (XRF-WDS) to ascertain the presence of uranium and tentatively evaluate its content by comparison with selected chemical components of the soil. A description of the experimental methodology adopted for the implemented easy-and-quick uranium assay is presented. Obtained results compare quite well to the data of certified time-consuming analytical tests of uranium in those soil samples. [1] L. Pilar (1966) Conditions of formation of Nisa uranium deposit (in Portuguese). Comunic. Serv. Geol. Portugal, tomo L, 50-85. [2] C. Gonçalves & J.V. Teixeira Lopes (1971) Uranium deposit of Nisa: geological aspects of its

  6. Surface Soil Moisture Assimilation with SWAT

    USDA-ARS?s Scientific Manuscript database

    Soil moisture is one of the most critical state variables in hydrologic modeling. Certain studies have demonstrated that assimilating observed surface soil moisture into a hydrologic model results in improved predictions of profile soil water content. With the Soil and Water Assessment Tool (SWAT), ...

  7. Surface modeling of soil antibiotics.

    PubMed

    Shi, Wen-jiao; Yue, Tian-xiang; Du, Zheng-ping; Wang, Zong; Li, Xue-wen

    2016-02-01

    Large numbers of livestock and poultry feces are continuously applied into soils in intensive vegetable cultivation areas, and then some veterinary antibiotics are persistent existed in soils and cause health risk. For the spatial heterogeneity of antibiotic residues, developing a suitable technique to interpolate soil antibiotic residues is still a challenge. In this study, we developed an effective interpolator, high accuracy surface modeling (HASM) combined vegetable types, to predict the spatial patterns of soil antibiotics, using 100 surface soil samples collected from an intensive vegetable cultivation area located in east of China, and the fluoroquinolones (FQs), including ciprofloxacin (CFX), enrofloxacin (EFX) and norfloxacin (NFX), were analyzed as the target antibiotics. The results show that vegetable type is an effective factor to be combined to improve the interpolator performance. HASM achieves less mean absolute errors (MAEs) and root mean square errors (RMSEs) for total FQs (NFX+CFX+EFX), NFX, CFX and EFX than kriging with external drift (KED), stratified kriging (StK), ordinary kriging (OK) and inverse distance weighting (IDW). The MAE of HASM for FQs is 55.1 μg/kg, and the MAEs of KED, StK, OK and IDW are 99.0 μg/kg, 102.8 μg/kg, 106.3 μg/kg and 108.7 μg/kg, respectively. Further, RMSE simulated by HASM for FQs (CFX, EFX and NFX) are 106.2 μg/kg (88.6 μg/kg, 20.4 μg/kg and 39.2 μg/kg), and less 30% (27%, 22% and 36%), 33% (27%, 27% and 43%), 38% (34%, 23% and 41%) and 42% (32%, 35% and 51%) than the ones by KED, StK, OK and IDW, respectively. HASM also provides better maps with more details and more consistent maximum and minimum values of soil antibiotics compared with the measured data. The better performance can be concluded that HASM takes the vegetable type information as global approximate information, and takes local sampling data as its optimum control constraints.

  8. Characteristic variations in reflectance of surface soils

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F. (Principal Investigator)

    1982-01-01

    Surface soil samples from a wide range of naturally occurring soils were obtained for the purpose of studying the characteristic variations in soil reflectance as these variations relate to other soil properties and soil classification. A total 485 soil samples from the U.S. and Brazil representing 30 suborders of the 10 orders of 'Soil Taxonomy' was examined. The spectral bidirectional reflectance factor was measured on uniformly moist soils over the 0.52 to 2.32 micron wavelength range with a spectroradiometer adapted for indoor use. Five distinct soil spectral reflectance curve forms were identified according to curve shape, the presence or absence of absorption bands, and the predominance of soil organic matter and iron oxide composition. These curve forms were further characterized according to generically homogeneous soil properties in a manner similar to the subdivisions at the suborder level of 'Soil Taxonomy'. Results indicate that spectroradiometric measurements of soil spectral bidirectional reflectance factor can be used to characterize soil reflectance in terms that are meaningful to soil classification, genesis, and survey.

  9. Pattern Effects of Soil on Photovoltaic Surfaces

    SciTech Connect

    Burton, Patrick D.; Hendrickson, Alex; Ulibarri, Stephen Seth; Riley, Daniel; Boyson, William E.; King, Bruce H.

    2016-06-06

    The texture or patterning of soil on PV surfaces may influence light capture at various angles of incidence (AOI). Accumulated soil can be considered a microshading element, which changes with respect to AOI. Laboratory deposition of simulated soil was used to prepare test coupons for simultaneous AOI and soiling loss experiments. A mixed solvent deposition technique was used to consistently deposit patterned test soils onto glass slides. Transmission decreased as soil loading and AOI increased. Dense aggregates significantly decreased transmission. But, highly dispersed particles are less prone to secondary scattering, improving overall light collection. In order to test AOI losses on relevant systems, uniform simulated soil coatings were applied to split reference cells to further examine this effect. Finally, the measured optical transmission and area coverage correlated closely to the observed $I_{{rm SC}}$. Angular losses were significant at angles as low as 25°.

  10. Pattern Effects of Soil on Photovoltaic Surfaces

    SciTech Connect

    Burton, Patrick D.; Hendrickson, Alex; Ulibarri, Stephen Seth; Riley, Daniel; Boyson, William E.; King, Bruce H.

    2016-06-06

    The texture or patterning of soil on PV surfaces may influence light capture at various angles of incidence (AOI). Accumulated soil can be considered a microshading element, which changes with respect to AOI. Laboratory deposition of simulated soil was used to prepare test coupons for simultaneous AOI and soiling loss experiments. A mixed solvent deposition technique was used to consistently deposit patterned test soils onto glass slides. Transmission decreased as soil loading and AOI increased. Dense aggregates significantly decreased transmission. But, highly dispersed particles are less prone to secondary scattering, improving overall light collection. In order to test AOI losses on relevant systems, uniform simulated soil coatings were applied to split reference cells to further examine this effect. Finally, the measured optical transmission and area coverage correlated closely to the observed $I_{{rm SC}}$. Angular losses were significant at angles as low as 25°.

  11. Pattern Effects of Soil on Photovoltaic Surfaces

    DOE PAGES

    Burton, Patrick D.; Hendrickson, Alex; Ulibarri, Stephen Seth; ...

    2016-06-06

    The texture or patterning of soil on PV surfaces may influence light capture at various angles of incidence (AOI). Accumulated soil can be considered a microshading element, which changes with respect to AOI. Laboratory deposition of simulated soil was used to prepare test coupons for simultaneous AOI and soiling loss experiments. A mixed solvent deposition technique was used to consistently deposit patterned test soils onto glass slides. Transmission decreased as soil loading and AOI increased. Dense aggregates significantly decreased transmission. But, highly dispersed particles are less prone to secondary scattering, improving overall light collection. In order to test AOI losses on relevant systems, uniform simulated soil coatings were applied to split reference cells to further examine this effect. Finally, the measured optical transmission and area coverage correlated closely to the observedmore » $$I_{{rm SC}}$$. Angular losses were significant at angles as low as 25°.« less

  12. The surface area of soil organic matter

    USGS Publications Warehouse

    Chiou, C.T.; Lee, J.-F.; Boyd, S.A.

    1990-01-01

    The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.The previously reported surface area for soil organic matter (SOM) of 560-800 m2/g as determined by the ethylene glycol (EG) retention method was reexamined by the standard BET method based on nitrogen adsorption at liquid nitrogen temperature. Test samples consisted of two high organic content soils, a freeze-dried soil humic acid, and an oven-dried soil humic acid. The measured BET areas for these samples were less than 1 m2/g, except for the freeze-dried humic acid. The results suggest that surface adsorption of nonionic organic compounds by SOM is practically insignificant in comparison to uptake by partition. The discrepancy between the surface areas of SOM obtained by BET and EG methods was explained in terms of the 'free surface area' and the 'apparent surface area' associated with these measurements.

  13. Pyrene fate in surface soil microcosms

    SciTech Connect

    Roper, J.C.; Pfaender, F.K.

    1995-12-31

    Polycyclic aromatic hydrocarbons are ubiquitous products of natural and anthropogenic combustion processes. They are also common contaminants at hazardous waste sites. This study assessed the fate of pyrene in pristine and previously exposed soils. Pyrene was incubated with surface soils in 1 liter microcosms. The study was performed using soil samples collected from the first 10 cm of a pristine forest soil profile and from soil at a former wood treatment site contaminated with creosote. Microcosms were constantly aerated and soil moisture was maintained at approximately 25%. Variations in the partitioning of pyrene incubated with soil into methanol and methylene chloride extractions were measured over time. Hydroxypyrene was found to be an abiotic transformation product in pristine soil. Products were separated from the extracts by HPLC and identified by GC/MS and compared to authentic standards. After an extended period of adaptation, mineralization began in the pristine soils while metabolism in the previously exposed soil was immediate. Fractionation of soils containing {sup 14}C-pyrene quantified a fraction of label which was neither degraded nor extractable using conventional methods. The amount of label in this fraction was related to the amount of microbial metabolism of the pyrene.

  14. Lunar soil and surface processes studies

    NASA Technical Reports Server (NTRS)

    Glass, B. P.

    1975-01-01

    Glass particles in lunar soil were characterized and compared to terrestrial analogues. In addition, useful information was obtained concerning the nature of lunar surface processes (e.g. volcanism and impact), maturity of soils and chemistry and heterogeneity of lunar surface material. It is felt, however, that the most important result of the study was that it demonstrated that the investigation of glass particles from the regolith of planetary bodies with little or no atmospheres can be a powerful method for learning about the surface processes and chemistry of planetary surfaces. Thus, the return of samples from other planetary bodies (especially the terrestrial planets and asteroids) using unmanned spacecraft is urged.

  15. HONO fluxes from soil surfaces: an overview

    NASA Astrophysics Data System (ADS)

    Wu, Dianming; Sörgel, Matthias; Tamm, Alexandra; Ruckteschler, Nina; Rodriguez-Caballero, Emilio; Cheng, Yafang; Pöschl, Ulrich; Weber, Bettina

    2016-04-01

    Gaseous nitrous acid (HONO) contributes up to 80% of atmospheric hydroxyl (OH) radicals and is also linked to health risks through reactions with tobacco smoke forming carcinogens. Field and modeling results suggested a large unknown HONO source in the troposphere during daytime. By measuring near ground HONO mixing ratio, up to 30% of HONO can be released from forest, rural and urban ground as well as snow surfaces. This source has been proposed to heterogeneous reactions of nitrogen dioxide (NO2) on humic acid surfaces or nitric acid photolysis. Laboratory studies showed that HONO emissions from bulk soil samples can reach 258 ng m-2 s-1 (in term of nitrogen), which corresponding to 1.1 × 1012 molecules cm-2 s-1and ˜ 100 times higher than most of the field studies, as measured by a dynamic chamber system. The potential mechanisms for soil HONO emissions include chemical equilibrium of acid-base reaction and gas-liquid partitioning between soil nitrite and HONO, but the positive correlation of HONO fluxes with pH (largest at neutral and slightly alkaline) points to the dominance of the formation process by ammonia-oxidizing bacteria (AOB). In general soil surface acidity, nitrite concentration and abundance of ammonia-oxidizing bacteria mainly regulate the HONO release from soil. A recent study showed that biological soil crusts in drylands can also emit large quantities of HONO and NO, corresponding to ˜20% of global nitrogen oxide emissions from soils under natural vegetation. Due to large concentrations of microorganisms in biological soil crusts, particularly high HONO and NO emissions were measured after wetting events. Considering large areas of arid and arable lands as well as peatlands, up to 70% of global soils are able to emitting HONO. However, the discrepancy between large soil HONO emissions measured in lab and low contributions of HONO flux from ground surfaces in field as well as the role of microorganisms should be further investigated.

  16. Acoustic techniques for studying soil-surface seals and crusts

    USDA-ARS?s Scientific Manuscript database

    The impact of raindrops on a soil surface during a rainstorm may cause soil-surface sealing and upon drying, soil crusting. Soil-surface sealing is a result of the clogging of interaggregate pores by smaller suspended particles in the water and by structural deformation of the soil fabric, which red...

  17. Global characterization of surface soil moisture drydowns

    NASA Astrophysics Data System (ADS)

    McColl, Kaighin A.; Wang, Wei; Peng, Bin; Akbar, Ruzbeh; Short Gianotti, Daniel J.; Lu, Hui; Pan, Ming; Entekhabi, Dara

    2017-04-01

    Loss terms in the land water budget (including drainage, runoff, and evapotranspiration) are encoded in the shape of soil moisture "drydowns": the soil moisture time series directly following a precipitation event, during which the infiltration input is zero. The rate at which drydowns occur—here characterized by the exponential decay time scale τ—is directly related to the shape of the loss function and is a key characteristic of global weather and climate models. In this study, we use 1 year of surface soil moisture observations from NASA's Soil Moisture Active Passive mission to characterize τ globally. Consistent with physical reasoning, the observations show that τ is lower in regions with sandier soils, and in regions that are more arid. To our knowledge, these are the first global estimates of τ—based on observations alone—at scales relevant to weather and climate models.

  18. Soil Surface Roughness through Image Analysis

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Saa-Requejo, A.; Valencia, J. L.; Moratiel, R.; Paz-Gonzalez, A.; Agro-Environmental Modeling

    2011-12-01

    Soil erosion is a complex phenomenon involving the detachment and transport of soil particles, storage and runoff of rainwater, and infiltration. The relative magnitude and importance of these processes depends on several factors being one of them surface micro-topography, usually quantified trough soil surface roughness (SSR). SSR greatly affects surface sealing and runoff generation, yet little information is available about the effect of roughness on the spatial distribution of runoff and on flow concentration. The methods commonly used to measure SSR involve measuring point elevation using a pin roughness meter or laser, both of which are labor intensive and expensive. Lately a simple and inexpensive technique based on percentage of shadow in soil surface image has been developed to determine SSR in the field in order to obtain measurement for wide spread application. One of the first steps in this technique is image de-noising and thresholding to estimate the percentage of black pixels in the studied area. In this work, a series of soil surface images have been analyzed applying several de-noising wavelet analysis and thresholding algorithms to study the variation in percentage of shadows and the shadows size distribution. Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010- 21501/AGR and by Xunta de Galicia through project no INCITE08PXIB1621 are greatly appreciated.

  19. Some surface properties of Apollo 17 soils

    NASA Technical Reports Server (NTRS)

    Holmes, H. F.; Fuller, E. L., Jr.; Gammage, R. B.

    1974-01-01

    The surface chemistry of Apollo 17 lunar fines samples 74220 (the orange soil) and 74241 (the gray control soil) has been studied by measuring the adsorption of nitrogen, argon, and oxygen (all at -196 C) and also water vapor (at 20 C or 22 C). In agreement with results for samples from other missions, both samples had low initial specific surface areas, consisted of nonporous particles, and were attacked by water vapor at high relative pressures to give an increased specific surface area and create a pore system which gave rise to a capillary condensation hysteresis loop in the adsorption isotherms. In contrast to previous samples, both of the Apollo 17 soils were partially hydrophobic in their initial interaction with water vapor (both samples were completely hydrophilic after the reaction with water). The results are consistent with formation at high temperatures without subsequent exposure to significant amounts of water.

  20. Cave-soils, the soils forming underneath the surface

    NASA Astrophysics Data System (ADS)

    Dobos, Endre; Bertóti, Diána; Kovács, Károly; Vadnai, Péter

    2015-04-01

    Limestone cave sediments of the Bükk-mountain in the North-Eastern part of Hungary were described, analysed and classified using WRB soil classification system. Cave sediments can be considered as soils, partly on the basis of their origin, partly of processes taking place in them. Based on the results, it can be concluded that cave soils are often shallow, lying directly above the continuous rock. In general they are layered, with clearly distinct layers of alluvial origin. Their organic matter content depends on the nature of the sediment. They often contain considerable quantities of undecomposed organic sediment, acting as the basis for very intensive soil life, which can be detected in the soil structure and may in some cases result in Vermic characteristics. The texture is very variable, ranging from clay to rough gravelly sand. Almost 100% of the soils are calcareous, the lime content is of secondary origin and its amount is at least 2%. Therefore, the pH values fluctuate from neutral to 8.5, mostly having a value around 8. In rare cases gley formation also occurs, especially on poorly drained areas, where there is no water flow to refresh the dissolved oxygen content. In the "oxy-aquic" state, characterized by high dissolved oxygen content, the iron is not reduced, so gley formation is not induced. From pedological point of view, cave sediments show a very diverse picture. Besides sedimentary layers, numerous soil formation processes can be detected, which can be considered analogue with surface processes, therefore they definitely need to be classified as soils. According to all these, in the Hungarian classification cave soils are primarily classified as alluvial, colluvial or lithomorphic soils. The WRB classification places them mainly in the Fluvisol and Leptosol Reference Groups, and according to the soils examined in the present work, they can be described with the Leptic (Epileptic), Fluvic (in rare cases Colluvic), Vermic, Calcaric, Eutric, Gleyic

  1. Estimating root zone soil water content using limited soils information and surface soil moisture data assimilation

    NASA Astrophysics Data System (ADS)

    Heathman, Gary Claude

    2001-10-01

    The various hydrologic processes of infiltration, redistribution, drainage, evaporation, and water uptake by plants are strongly interdependent, as they occur sequentially or simultaneously. An important state variable that strongly influences the magnitude to which these rate processes occur is the amount of water present within the root zone, and in particular, the top few centimeters near the soil surface. Traditionally, measurements of soil moisture have been limited to point measurements made in the field. In general, averages of point measurements are used to characterize the soil moisture of an area, but these averages seldom yield information that is adequate to characterize large scale hydrologic processes. Recent advancements in remote sensing now make it possible to obtain areal estimates of surface soil moisture. The use of remotely sensed data to estimate surface soil moisture, combined with soil water and hydrologic modeling, provides a unique opportunity to advance our understanding of hydrologic processes at a much larger scale. Standard techniques for measuring soil moisture have been well documented, with commercial instrumentation being widely available. Various computer models have been developed to estimate soil moisture in the root and vadose zone, although their application over large scales is limited due to varying spatial and temporal field conditions. It is the combination of ground-based data (in-situ measurements), near-surface soil moisture data, and modeling that form the basis for this research. The interactive use of field research, remote sensing ground truth data, and integrated systems modeling is used to describe surface and profile soil moisture conditions at several locations within a large watershed. Successful application of this approach should improve our capabilities for estimating soil hydraulic properties and to better estimate water and chemical transport in the root zone, thus enhancing water use efficiency and plant

  2. Soil water balance changes in engineered soil surfaces

    SciTech Connect

    Saskschewsky, M.R.; Kemp, C.J.; Link, S.O.; Waugh, W.J.

    1995-03-01

    Permanent disposal of radioactive waste requires the construction of isolation barriers that minimize both recharge and erosion. Recharge can be prevented by storing precipitation near the surface so that it will be returned to the atmosphere via evapotranspiration. Erosion can be reduced with gravel mulch, but thick gravel layers may increase recharge. Gravel mixed into the surface soil may provide erosion protection without increasing recharge. To comprae the effects that erosion control has on infiltration, two lysimeter experiments were conducted to examine the effects of sand and gravel mulches and gravel admixitures, using two precipitation regimens and with or without vegetation.

  3. Soil moisture sensor calibration for organic soil surface layers

    NASA Astrophysics Data System (ADS)

    Bircher, S.; Andreasen, M.; Vuollet, J.; Vehviläinen, J.; Rautiainen, K.; Jonard, F.; Weihermüller, L.; Zakharova, E.; Wigneron, J.-P.; Kerr, Y. H.

    2015-12-01

    This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology HOBE. For the Decagon 5TE sensor such a function is currently not reported in literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified: for the Decagon 5TE apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger non-linearity in the sensor response and signal saturation in the high level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and HOBE sites are

  4. Soil moisture sensor calibration for organic soil surface layers

    NASA Astrophysics Data System (ADS)

    Bircher, Simone; Andreasen, Mie; Vuollet, Johanna; Vehviläinen, Juho; Rautiainen, Kimmo; Jonard, François; Weihermüller, Lutz; Zakharova, Elena; Wigneron, Jean-Pierre; Kerr, Yann H.

    2016-04-01

    This paper's objective is to present generic calibration functions for organic surface layers derived for the soil moisture sensors Decagon ECH2O 5TE and Delta-T ThetaProbe ML2x, using material from northern regions, mainly from the Finnish Meteorological Institute's Arctic Research Center in Sodankylä and the study area of the Danish Center for Hydrology (HOBE). For the Decagon 5TE sensor such a function is currently not reported in the literature. Data were compared with measurements from underlying mineral soils including laboratory and field measurements. Shrinkage and charring during drying were considered. For both sensors all field and lab data showed consistent trends. For mineral layers with low soil organic matter (SOM) content the validity of the manufacturer's calibrations was demonstrated. Deviating sensor outputs in organic and mineral horizons were identified. For the Decagon 5TE, apparent relative permittivities at a given moisture content decreased for increased SOM content, which was attributed to an increase of bound water in organic materials with large specific surface areas compared to the studied mineral soils. ThetaProbe measurements from organic horizons showed stronger nonlinearity in the sensor response and signal saturation in the high-level data. The derived calibration fit functions between sensor response and volumetric water content hold for samples spanning a wide range of humus types with differing SOM characteristics. This strengthens confidence in their validity under various conditions, rendering them highly suitable for large-scale applications in remote sensing and land surface modeling studies. Agreement between independent Decagon 5TE and ThetaProbe time series from an organic surface layer at the Sodankylä site was significantly improved when the here-proposed fit functions were used. Decagon 5TE data also well-reflected precipitation events. Thus, Decagon 5TE network data from organic surface layers at the Sodankylä and

  5. A seismicity boundary in the low-strain region of Alentejo, south Portugal

    NASA Astrophysics Data System (ADS)

    Matos, Catarina; Zahradník, Jirí; Arroucau, Pierre; Silveira, Graça; Custódio, Susana

    2017-04-01

    Mainland Portugal lays on a stable continental setting characterized by low strain rates (convergence velocities < 1 mm/yr). However, the region has been the source of documented moderate magnitude earthquakes. The Alentejo region (south Portugal) presents belts of high epicenter density, the two main ones being (1) the Viana do Alentejo cluster in the south and (2) the NW-SE oriented Arraiolos alignment in the north. The latter appears as a sharp transition between a nearly aseismic area to the north and a seismically active area to the south. Active fault studies based on geological observations have not identified tectonic features able to explain the observed seismicity patterns. Our objective is to contribute to the understanding of the deformation pattern in south Portugal. Several hypotheses need to be addressed: (1) Are those clusters the expression of a broad region of distributed deformation?; (2) Do they mark structures that might have the potential to generate moderate magnitude events? We use a high-quality dataset recorded by a temporary array deployed in the area to produce a robust image of earthquake locations and to compute focal mechanisms. Newly detected events match well the previously identified earthquake alignments. The local network provides good control of the focal depths. We observe a spatial variation in the depth distribution. The Arraiolos alignment seems to produce deeper earthquakes than the Viana do Alentejo cluster. Earthquake locations inferred using 1D and 3D velocity models show a persistent concentration of seismicity at middle to lower crust depths (15 - 30 km) in the SE section of that alignment. We also present relocation of instrumental seismicity for the period (1970-2016). Previous studies show that a strike-slip faulting regime dominates mainland Portugal. IPMA (Instituto Português do Mar e da Atmosfera) routinely computes focal mechanisms for earthquakes with reported local magnitudes of 3.5 or greater using the

  6. Soil erosion and surface runoff model SMODERP

    NASA Astrophysics Data System (ADS)

    Kavka, P.; Vrana, K.; Dostal, T.

    2012-04-01

    This contribution presents a software tool for calculation and prediction of soil erosion and surface runoff from agricultural lands. There is no universal tool to properly describe the origin and the processes related to the surface runoff and sediment transport in different scales. For a design of any technical erosion control measures, that are used to interrupt the surface runoff, it is necessary to identify basic outflow characteristics (discharge, flow volume). Numerical model SMODERP was developed for determination of these characteristics. The model is being developed at the Department of Irrigation, Drainage and Landscape Engineering , Civil Engineering Faculty, CTU in Prague. SMODERP is physically based one-dimensional episodic model that includes the processes of infiltration, surface retention, surface roughness and vegetation impact on runoff. The model has been substantially upgraded and tested in last few years. Especially runoff parameters, time and spatial discretisation were recalibrated and validated. Runoff parameters were recalibrated on the set of forty measurements performed on the laboratory rainfall simulator on five soil types. The parameters were designed for five soil types categories according to content of particles with size up to 0.01 mm (Novak soil classification). The precipitation episodes can be chosen from the attached catalogue or can be designed by a user. We also present how the input data can be obtained based on available resources (soil maps and data, land use, terrain models, field research, etc.) and how can be used in the assessment erosion risk and in designing of erosion control measures. The model is meant to be used not only for the research purposes, but mainly for the engineering practice. We present the new version of the model that includes a new user friendly graphical interface. The research has been supported by the research grants SGS SGS11/148/OHK1/3T/11 "Experimental Research on Rainfall-runoff and Erosion

  7. Estimation of soil moisture from diurnal surface temperature observations

    NASA Technical Reports Server (NTRS)

    Vandegriend, A. A.; Camillo, P. J.

    1986-01-01

    A coupled heat and moisture balance model was used to determine the thermal inertia of a grass covered top soil under different meteorological conditions. Relations between thermal inertia and soil moisture were established using the De Vries models for thermal conductivity and heat capacity to relate soil moisture and thermal inertia as a function of soil type. A sensitivity study of the surface roughness length and thermal inertia on diurnal surface temperature shows the necessity of focusing on the night time surface temperature rather than on the day time surface temperature, in order to estimate the soil moisture content of the top soil.

  8. Estimation of soil moisture from diurnal surface temperature observations

    NASA Technical Reports Server (NTRS)

    Vandegriend, A. A.; Camillo, P. J.

    1986-01-01

    A coupled heat and moisture balance model was used to determine the thermal inertia of a grass covered top soil under different meteorological conditions. Relations between thermal inertia and soil moisture were established using the De Vries models for thermal conductivity and heat capacity to relate soil moisture and thermal inertia as a function of soil type. A sensitivity study of the surface roughness length and thermal inertia on diurnal surface temperature shows the necessity of focusing on the night time surface temperature rather than on the day time surface temperature, in order to estimate the soil moisture content of the top soil.

  9. Provenance of upper Triassic sandstone, southwest Iberia (Alentejo and Algarve basins): tracing variability in the sources

    NASA Astrophysics Data System (ADS)

    Pereira, M. F.; Ribeiro, C.; Gama, C.; Drost, K.; Chichorro, M.; Vilallonga, F.; Hofmann, M.; Linnemann, U.

    2017-01-01

    Laser ablation ICP-MS U-Pb analyses have been conducted on detrital zircon of Upper Triassic sandstone from the Alentejo and Algarve basins in southwest Iberia. The predominance of Neoproterozoic, Devonian, Paleoproterozoic and Carboniferous detrital zircon ages confirms previous studies that indicate the locus of the sediment source of the late Triassic Alentejo Basin in the pre-Mesozoic basement of the South Portuguese and Ossa-Morena zones. Suitable sources for the Upper Triassic Algarve sandstone are the Upper Devonian-Lower Carboniferous of the South Portuguese Zone (Phyllite-Quartzite and Tercenas formations) and the Meguma Terrane (present-day in Nova Scotia). Spatial variations of the sediment sources of both Upper Triassic basins suggest a more complex history of drainage than previously documented involving other source rocks located outside present-day Iberia. The two Triassic basins were isolated from each other with the detrital transport being controlled by two independent drainage systems. This study is important for the reconstruction of the late Triassic paleogeography in a place where, later, the opening of the Central Atlantic Ocean took place separating Europe from North America.

  10. Turbulence-induced thermal signatures over evaporating bare soil surfaces

    NASA Astrophysics Data System (ADS)

    Haghighi, Erfan; Or, Dani

    2015-07-01

    Soil wetness and airflow turbulence are key factors affecting surface energy balance components thereby influencing surface skin temperature. Turbulent eddies interacting with evaporating surfaces often induce localized and intermittent evaporative and sensible heat fluxes that leave distinct thermal signatures. These surface thermal fluctuations observable by infrared thermography (IRT) offer a means for characterization of overlaying turbulent airflows and remote quantification of surface wetness. We developed a theoretical and experimental methodology for using rapid IR surface temperature measurements to deduce surface wetness and evaporative fluxes from smooth bare soils. The mechanistic model provides theoretical links between surface thermal fluctuations, soil, and aerodynamic properties enabling thermal inferences of soil wetness with explicit consideration of soil thermal capacity and airflow turbulence effects. The method potentially improves accuracy of soil wetness assessment by IRT-based techniques whose performance is strongly influenced by surface-turbulence interactions and offers new ways for quantifying fluxes directly at their origin.

  11. Impact of surface coal mining on soil hydraulic properties

    Treesearch

    X. Liu; J. Q. Wu; P. W. Conrad; S. Dun; C. S. Todd; R. L. McNearny; William Elliot; H. Rhee; P. Clark

    2016-01-01

    Soil erosion is strongly related to soil hydraulic properties. Understanding how surface coal mining affects these properties is therefore important in developing effective management practices to control erosion during reclamation. To determine the impact of mining activities on soil hydraulic properties, soils from undisturbed areas, areas of roughly graded mine...

  12. Grass mulching effect on infiltration, surface runoff and soil loss of three agricultural soils in Nigeria.

    PubMed

    Adekalu, K O; Olorunfemi, I A; Osunbitan, J A

    2007-03-01

    Mulching the soil surface with a layer of plant residue is an effective method of conserving water and soil because it reduces surface runoff, increases infiltration of water into the soil and retard soil erosion. The effectiveness of using elephant grass (Pennisetum purpureum) as mulching material was evaluated in the laboratory using a rainfall simulator set at rainfall intensities typical of the tropics. Six soil samples, two from each of the three major soil series representing the main agricultural soils in South Western Nigeria were collected, placed on three different slopes, and mulched with different rates of the grass. The surface runoff, soil loss, and apparent cumulative infiltration were then measured under each condition. The results with elephant grass compared favorably with results from previous experiments using rice straw. Runoff and soil loss decreased with the amount of mulch used and increased with slope. Surface runoff, infiltration and soil loss had high correlations (R = 0.90, 0.89, and 0.86, respectively) with slope and mulch cover using surface response analysis. The mean surface runoff was correlated negatively with sand content, while mean soil loss was correlated positively with colloidal content (clay and organic matter) of the soil. Infiltration was increased and soil loss was reduced greatly with the highest cover. Mulching the soils with elephant grass residue may benefit late cropping (second cropping) by increasing stored soil water for use during dry weather and help to reduce erosion on sloping land.

  13. Acoustic Techniques for Studying Soil-surface Seals and Crusts

    NASA Astrophysics Data System (ADS)

    Hickey, C. J.; Leary, D.; Dicarlo, D. A.

    2007-05-01

    The impact of raindrops on a soil surface during a rainstorm may cause soil-surface sealing and crusting. Soil- surface sealing is a result of the clogging in interaggregate pores by smaller suspended particles in the water, which reduces the infiltration capacity of soils. Soil-surface crusting refers to the increase in soil strength or mechanical stiffness associated with near surface compaction or densification. The formation of soil-surface seals and crusts have a profound influence on the erodability of soils, with the consensus being that the reduced hydraulic conductivity due to sealing is the more important factor. However, studies note that measured values of seal hydraulic conductivity are few. The reason so few measurements may be because the thickness of the altered surface layer is on the order of millimeters. For example Lee (2006) states that a soil-surface seal consist of two parts: a 0.1mm thick upper skin seal attributed to compaction by the rain drop impact and a deeper 1.5 mm "washed in" zone with decreased porosity due to the accumulation of particles. Bulk density profiles measured using X-radiography show maximum changes in the top 5 mm of the soil. The surface of the ground (soil) has an influence on the propagation of sound outdoors. The porosity, air flow- resistivity, and tortuosity of the ground are the properties, which characterize the influence of the ground on the airborne sound. The air flow-resistivity of a dry soil is equivalent to the hydraulic conductivity of a water-saturated soil. In this presentation we discuss two acoustic techniques, one with sensitivity to changes in hydraulic properties (sealing) and the other to changes in mechanical stiffness (crusting). These non-contact techniques excite the soil using a suspended loudspeaker to impinge acoustic energy from the air (sound) onto the sample. The response of the soil is quantified using a microphone to measure the total pressure above the soil surface and a laser Doppler

  14. Estimating soil hydraulic properties from ground based IR soil surface temperature and TDR measurements

    NASA Astrophysics Data System (ADS)

    Steenpass, C.; Vanderborght, J.; Herbst, M.; Vereecken, H.

    2009-12-01

    State variables like the soil water content and soil temperature with location and time contain information about soil specific properties, since soil temperature and the rate of water movement to the soil surface are being determined by properties such as thermal and hydraulic conductivity. By evaporation, latent heat is being removed from the soil in form of water vapor. This cooling effect depends on the water availability in the upper part of the soil. The water availability itself depends on the hydraulic properties of the soil. Therefore, temporal variability of the soil surface temperature should be sensitive to soil hydraulic properties. An experiment has been performed during September 2008 at a test site close to the Research Center Juelich to estimate soil hydraulic properties and correlations to the soil surface temperature, as measured by an IR camera. Soil water content and temperatures have been measured in different depths. To investigate the information content of soil surface temperatures to derive soil hydraulic properties or find out how strong estimated hydraulic properties are being constraint by the soil surface temperature, various numerical experiments have been performed: The general applicability of this method was checked with numerically generated data as well as real measured data. By simulating with a one-material soil profile, we estimated effective soil hydraulic properties to test how good these parameters are in the prediction of the soil water dynamics in deeper soil layers (>10 cm). Usage of a layered soil profile in a simulation allowed us to estimate soil hydraulic properties for different depths, thus being able to match the measured data (soil surface temperature and moisture in different depths) as good as possible. For the numerical modeling we used a one-dimensional coupled heat and water flow model linked to a Markov Chain Monte-Carlo based algorithm. As not only the estimated parameters but also their uncertainties are

  15. A Bayesian Approach to the Orientations of Central Alentejo Megalithic Enclosures

    NASA Astrophysics Data System (ADS)

    Pimenta, Fernando; Tirapicos, Luís; Smith, Andrew

    2009-12-01

    In this work we have conducted a study on the orientations in the landscape of twelve megalithic enclosures in the Alentejo region of southern Portugal. Some of these sites date back to the sixth or fifth millennium B.C. and are among the oldest stone enclosures in Europe. The results of the survey show a pattern toward eastern rising orientations. We used dedicated GIS software from one of the authors to produce horizon profiles and applied a statistical Bayesian approach in an attempt to check how the data would fit to different models. In particular, we tested our results for a possible ritual interest in the Autumn or Harvest Full Moon and discuss previous studies by Michael Hoskin and colleges on the orientations of seven stone dolmens of this area that have shown the existence of a possible custom for an orientation toward the sunrise.

  16. Divergent surface and total soil moisture projections under global warming

    USGS Publications Warehouse

    Berg, Alexis; Sheffield, Justin; Milly, Paul C.D.

    2017-01-01

    Land aridity has been projected to increase with global warming. Such projections are mostly based on off-line aridity and drought metrics applied to climate model outputs but also are supported by climate-model projections of decreased surface soil moisture. Here we comprehensively analyze soil moisture projections from the Coupled Model Intercomparison Project phase 5, including surface, total, and layer-by-layer soil moisture. We identify a robust vertical gradient of projected mean soil moisture changes, with more negative changes near the surface. Some regions of the northern middle to high latitudes exhibit negative annual surface changes but positive total changes. We interpret this behavior in the context of seasonal changes in the surface water budget. This vertical pattern implies that the extensive drying predicted by off-line drought metrics, while consistent with the projected decline in surface soil moisture, will tend to overestimate (negatively) changes in total soil water availability.

  17. Quantification of soil surface roughness evolution under simulated rainfall

    USDA-ARS?s Scientific Manuscript database

    Soil surface roughness is commonly identified as one of the dominant factors governing runoff and interrill erosion. The objective of this study was to compare several existing soil surface roughness indices and to test the Revised Triangular Prism surface area Method (RTPM) as a new approach to cal...

  18. Variations in FASST Predictions of Soil Surface Temperatures

    DTIC Science & Technology

    2006-04-01

    shows more variation in temperature with perturbations in incident solar radiation. That the low-albedo soil would have the hottest surface is...ER D C/ CR R EL T R -0 6 -9 Variations in FASST Predictions of Soil Surface Temperatures Lindamae Peck April 2006 C ol d R eg io n s...April 2006 Variations in FASST Predictions of Soil Surface Temperatures Lindamae Peck Cold Regions Research and Engineering Laboratory U.S

  19. The utility of surface temperature measurements for the remote sensing of surface soil water status

    NASA Technical Reports Server (NTRS)

    Idso, S. B.; Jackson, R. D.; Reginato, R. J.; Schmugge, T. J.

    1975-01-01

    Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day-night periods. They were also found to be linear functions of the daily maximum value of the surface soil-air-temperature differential. Tests on three additional soils ranging from sandy loam to clay indicated that the relations determined for Avondale loam could not be accurately applied to these other soil types. When the moisture characteristic curves of each soil were used to transform water contents into pressure potentials, however, it was found that soil water pressure potential could be determined without prior knowledge of soil type, and thus its value as a potential soil water status survey tool was significantly enhanced.

  20. The utility of surface temperature measurements for the remote sensing of surface soil water status

    NASA Technical Reports Server (NTRS)

    Idso, S. B.; Jackson, R. D.; Reginato, R. J.; Schmugge, T. J.

    1975-01-01

    Experiments carried out on an Avondale loam soil indicated that the thermal inertia concept of soil water content detection is reasonably sound. The volumetric water contents of surface soil layers between 2 and 4 cm thick were found to be linear functions of the amplitude of the diurnal surface soil temperature wave for clear day-night periods. They were also found to be linear functions of the daily maximum value of the surface soil-air-temperature differential. Tests on three additional soils ranging from sandy loam to clay indicated that the relations determined for Avondale loam could not be accurately applied to these other soil types. When the moisture characteristic curves of each soil were used to transform water contents into pressure potentials, however, it was found that soil water pressure potential could be determined without prior knowledge of soil type, and thus its value as a potential soil water status survey tool was significantly enhanced.

  1. Soil Carbon Dioxide Production and Surface Fluxes: Subsurface Physical Controls

    NASA Astrophysics Data System (ADS)

    Risk, D.; Kellman, L.; Beltrami, H.

    Soil respiration is a critical determinant of landscape carbon balance. Variations in soil temperature and moisture patterns are important physical processes controlling soil respiration which need to be better understood. Relationships between soil respi- ration and physical controls are typically addressed using only surface flux data but other methods also exist which permit more rigorous interpretation of soil respira- tion processes. Here we use a combination of subsurface CO_{2} concentrations, surface CO_{2} fluxes and detailed physical monitoring of the subsurface envi- ronment to examine physical controls on soil CO_{2} production at four climate observatories in Eastern Canada. Results indicate that subsurface CO_{2} produc- tion is more strongly correlated to the subsurface thermal environment than the surface CO_{2} flux. Soil moisture was also found to have an important influence on sub- surface CO_{2} production, particularly in relation to the soil moisture - soil profile diffusivity relationship. Non-diffusive profile CO_{2} transport appears to be im- portant at these sites, resulting in a de-coupling of summertime surface fluxes from subsurface processes and violating assumptions that surface CO_{2} emissions are the result solely of diffusion. These results have implications for the study of soil respiration across a broad range of terrestrial environments.

  2. Surveying the Alentejo continental shelf for minerals and Quaternary environmental changes: preliminary results of the MINEPLAT project survey

    NASA Astrophysics Data System (ADS)

    Noiva, João; Ribeiro, Carlos; Terrinha, Pedro; Brito, Pedro; Neres, Marta

    2017-04-01

    The tectonic uplift of South Portugal in the last 5 Million years (My) was firstly identified on the basis of morphologic criteria by Mariano Feio (1952, "The evolution of the relief of Baixo Alentejo and Algarve", transl.). However, the assessment of continental vertical movements off Portugal and its relation with tectonics was only initiated in the 1990-ies. This work was carried out in the framework of FP6 and FP7 in the domains of Natural Hazards funded by the European Community. The swath bathymetry cartography of the southwest part of the Iberian Peninsula resulted from the effort of European and national projects, of 19 oceanographic surveys, a total of 200 ship time days executed from 2000 to 2006, involving 14 research institutions from 7 European countries. As a result of this effort together with acquisition and interpretation of thousands of km of seismic reflection profiles, the Pliocene-Quaternary uplift of the Alentejo continental margin (SW Portugal) is now widely accepted by the scientific community. This uplift has not been yet quantified but it is possible that can have contributed to erosion and deposition of metallic ores as placers in the continental shelf. This argues in favor of the potential existence of placers in the continental shelf and the need for the detailed investigation that will allow determination of ideal location for placers deposition in the past Pliocene-Quaternary (5 My). The source for metals can arguably be associated to the Iberian Pyrite Belt ores hosted in the Alentejo Paleozoic formations and to the hyper-alkaline intrusions of Sines and Monchique of Late Cretaceous age. Artificial renourishment of beaches with offshore sand has not been assessed for the Alentejo littoral, despite that the coast located to the south of the Sines segment shows high susceptibility to erosion. This has been observed on a regular basis as the beaches are frequently devoid of sand, thus jeopardizing their touristic potential. The detailed

  3. Plutonium, (137)Cs and uranium isotopes in Mongolian surface soils.

    PubMed

    Hirose, K; Kikawada, Y; Igarashi, Y; Fujiwara, H; Jugder, D; Matsumoto, Y; Oi, T; Nomura, M

    2017-01-01

    Plutonium ((238)Pu and (239,240)Pu), (137)Cs and plutonium activity ratios ((238)Pu/(239,240)Pu) as did uranium isotope ratio ((235)U/(238)U) were measured in surface soil samples collected in southeast Mongolia. The (239,240)Pu and (137)Cs concentrations in Mongolian surface soils (<53 μm of particle size) ranged from 0.42 ± 0.03 to 3.53 ± 0.09 mBq g(-1) and from 11.6 ± 0.7 to 102 ± 1 mBq g(-1), respectively. The (238)Pu/(239,240)Pu activity ratios in the surface soils (0.013-0.06) coincided with that of global fallout. The (235)U/(238)U atom ratios in the surface soil show the natural one. There was a good correlation between the (239,240)Pu and (137)Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between (239,240)Pu and (137)Cs from (137)Cs/(239,240)Pu - (137)Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than (137)Cs.

  4. The global distribution and dynamics of surface soil moisture

    NASA Astrophysics Data System (ADS)

    McColl, Kaighin A.; Alemohammad, Seyed Hamed; Akbar, Ruzbeh; Konings, Alexandra G.; Yueh, Simon; Entekhabi, Dara

    2017-01-01

    Surface soil moisture has a direct impact on food security, human health and ecosystem function. It also plays a key role in the climate system, and the development and persistence of extreme weather events such as droughts, floods and heatwaves. However, sparse and uneven observations have made it difficult to quantify the global distribution and dynamics of surface soil moisture. Here we introduce a metric of soil moisture memory and use a full year of global observations from NASA's Soil Moisture Active Passive mission to show that surface soil moisture--a storage believed to make up less than 0.001% of the global freshwater budget by volume, and equivalent to an, on average, 8-mm thin layer of water covering all land surfaces--plays a significant role in the water cycle. Specifically, we find that surface soil moisture retains a median 14% of precipitation falling on land after three days. Furthermore, the retained fraction of the surface soil moisture storage after three days is highest over arid regions, and in regions where drainage to groundwater storage is lowest. We conclude that lower groundwater storage in these regions is due not only to lower precipitation, but also to the complex partitioning of the water cycle by the surface soil moisture storage layer at the land surface.

  5. Soil remediation by surface heating and vacuum extraction

    SciTech Connect

    Stegemeir, G.L.; Vinegar, H.J.

    1995-12-01

    A novel in-situ, thermal-vacuum method has been developed to remove contaminants from near-surface soils and pavements. Heat is supplied to the soil by downward conduction from a surface heater. Vaporized products are collected under an impermeable sheet into a vacuum system for further treatment or disposal.

  6. Using IR-measured soil surface temperatures to estimate hydraulic properties of the top soil layer

    NASA Astrophysics Data System (ADS)

    Steenpass, Christian; Vanderborght, Jan; Herbst, Michael; Simunek, Jirka; Vereecken, Harry

    2010-05-01

    The temporal and spatial development of soil surface temperatures (SST) depends on water availability in the near-surface soil layer. Since the soil loses latent heat during evaporation and water available for evaporation depends on soil hydraulic properties (SHP), the temporal variability of SST should contain information about the near-surface SHP. This study was conducted to investigate the information content of soil surface temperatures for estimation of soil hydraulic properties and their uncertainties, and to determine the effect of soil tillage on near-surface SHP. A hydrological model (HYDRUS-1D) coupled with a global optimizer (DREAM) was used to inversely estimate the van Genuchten-Mualem parameters of SHP from infra-red measured SST and TDR-measured water contents. The general applicability of this approach was tested using synthetic data. The same approach was then applied to a real data set, which was collected during September 2008 in Selhausen, Germany. The synthetic data set was generated using HYDRUS-1D for the same initial and boundary conditions and measurement protocol as the real data set. Using synthetic and real data it was found that although estimated SHP are sensitive to SST, their estimates are relatively uncertain when only information about SST is used. These uncertainties can be reduced by additionally considering also measured soil water contents. A comparison of SHP determined in the laboratory on undisturbed soil samples with those estimated from SST and TDR data measured in a harrowed soil showed similar results for the deeper undisturbed soil and large differences for the harrowed part of the soil profile. This shows the important effect of soil tillage on soil hydraulic properties. Application of the method in the field to characterize the hydraulic properties of the upper soil layer may reduce the amount of needed in-soil measurements and therefore allows larger scale observations.

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

    USDA-ARS?s Scientific Manuscript database

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

  8. Close or not so close? Provenance studies of megalithic monuments from Alentejo (Portugal)

    NASA Astrophysics Data System (ADS)

    Boaventura, R.; Moita, P.

    2012-04-01

    There has been a significant amount of studies about megalithic tombs conducted in the Alentejo region. However the geological provenance of monoliths used in the construction of those tombs usually was not a priority among researchers with rare exceptions (Dehn, Kalb and Vortisch, 1991; Boaventura, 2000). Recent studies of dolmens (Oliveira, 1997 and 2006; Gonçalves, 2003) refer only to a brief characterization of rocks, such as "granite or schist slabs", highlighting certain types if the geological stratum is identical or not to the stone blocks. On the other hand, when the type of raw material appears to be similar with the bedrock, it is common and empirically assumed its local provenance. With the aim of testing and expand the knowledge about the provenance of the slabs used in the construction of megalithic tombs, several lithic samples from dolmen slabs and outcrops in their surroundings were collected for analysis and comparison. The samples were characterized by petrographic studies in thin section as well with a geochemical analyses performed by XRF that gives major elements as well some trace elements. The dolmens tested for this project are located roughly between the northeast to west of the town of Monforte (Upper region of Alentejo, Portugal) and are named, from south to north, as Serrinha, Rabuje group (1 to 5), Geodésico de Besteiros 3 and Velho. The field work and petrographic studies revealed that the slabs are constituted mainly by several types of granitoids (gnaissic, red, white, tonalitic), amphibolites and mottled schist shale. The comparison of chemical analyses between slabs and selected outcrops revealed that the provenances are in most of the cases from the nearby geological stratum. In fact, major elements (e.g. MgO, SiO2, CaO) as well trace elements (e.g. Sr, Y, Zr, Nb) compositions are similar on slab samples and in rocks from the outcrops. If in terms of major elements a similarity was already expectable, or easier to obtain, the

  9. Biochar Amendment to the Soil Surface Reduces Fumigant Emissions and Enhances Soil Microorganism Recovery.

    PubMed

    Shen, Guoqing; Ashworth, Daniel J; Gan, Jay; Yates, Scott R

    2016-02-02

    During soil fumigation, it is ideal to mitigate soil fumigant emissions, ensure pest control efficacy, and speed up the recovery of the soil microorganism population established postapplication. However, no current fumigant emission reduction strategy can meet all these requirements. In the present study, replicated soil columns were used to study the effect of biochar derived from rice husk (BR) and green waste (BG) applied to the soil surface on 1,3-dichloropropene (1,3-D) and chloropicrin (CP) emissions and soil gas distribution, and on microorganism population re-establishment. Relative to fumigated bare soil (no emission reduction strategy), high-density polyethylene (HDPE), and ammonium thiosulfate (ATS) treatments, BR gave dramatic emission reductions for both fumigants with no obvious emission peak, whereas BG was very effective only for 1,3-D. With BR application, the concentration of fumigant in the soil gas was higher than in the bare soil and ATS treatment. After the soil column experiment, mixing the BR with the fumigated soil resulted in higher soil respiration rates than were observed for HDPE and ATS treatments. Therefore, biochar amendment to the soil surface may be an effective strategy for fumigant emission reduction and the recovery of soil microorganism populations established postapplication.

  10. Testing continuous earthquake detection and location in Alentejo (South Portugal) by waveform coherency analysis

    NASA Astrophysics Data System (ADS)

    Matos, Catarina; Grigoli, Francesco; Cesca, Simone; Custódio, Susana

    2015-04-01

    In the last decade a permanent seismic network of 30 broadband stations, complemented by dense temporary deployments, covered Portugal. This extraordinary network coverage enables now the computation of a high-resolution image of the seismicity of Portugal, which in turn will shed light on the seismotectonics of Portugal. The large data volumes available cannot be analyzed by traditional time-consuming manual location procedures. In this presentation we show first results on the automatic detection and location of earthquakes occurred in a selected region in the south of Portugal Our main goal is to implement an automatic earthquake detection and location routine in order to have a tool to quickly process large data sets, while at the same time detecting low magnitude earthquakes (i.e., lowering the detection threshold). We present a modified version of the automatic seismic event location by waveform coherency analysis developed by Grigoli et al. (2013, 2014), designed to perform earthquake detections and locations in continuous data. The event detection is performed by continuously computing the short-term-average/long-term-average of two different characteristic functions (CFs). For the P phases we used a CF based on the vertical energy trace, while for S phases we used a CF based on the maximum eigenvalue of the instantaneous covariance matrix (Vidale 1991). Seismic event detection and location is obtained by performing waveform coherence analysis scanning different hypocentral coordinates. We apply this technique to earthquakes in the Alentejo region (South Portugal), taking advantage from a small aperture seismic network installed in the south of Portugal for two years (2010 - 2011) during the DOCTAR experiment. In addition to the good network coverage, the Alentejo region was chosen for its simple tectonic setting and also because the relationship between seismicity, tectonics and local lithospheric structure is intriguing and still poorly understood. Inside

  11. Fixation of virgin lunar surface soil

    NASA Technical Reports Server (NTRS)

    Conley, J. M.; Frazer, R.; Cannon, W. A.

    1972-01-01

    Two systems are shown to be suitable for fixing loose particulate soils with a polymer film, without visually detectable disturbance of the soil particle spatial relationships. A two-component system is described, which uses a gas monomer condensible at the soil temperature and a gas phase catalyst acting to polymerize the monomer. A one-component system using a monomer which polymerizes spontaneously on and within the top few millimeters of the soil is also considered. The two-component system employs a simpler apparatus, but it operates over a narrower temperature range (approximately -40 to -10 C). Other two-component systems were identified which may operate at soil temperatures as high as +100 C, at relatively narrow temperature ranges of approximately 30 C. The one-component system was demonstrated to operate successfully with initial soil temperatures from -70 C or lower to +150 C.

  12. Scaling surface soil moisture in the Walnut Gulch Experimental Watershed

    NASA Astrophysics Data System (ADS)

    Cosh, M. H.; Jackson, T. J.; Moran, S.; Bindlish, R.; Mladenova, I.

    2006-05-01

    The estimation of surface soil moisture in semi-arid and arid regions is complicated by the inherent heterogeneous precipitation patterns and ephemeral surface water characteristics. Large-scale sampling is inefficient for long term monitoring of surface soil moisture, especially with the goal of calibration of a satellite soil moisture product such as that generated by the AMSR-E instrument for example. Statistical methods of accurately monitoring and scaling point and watershed estimates to satellite scale moisture values are explored. The location for this study is the Walnut Gulch Experimental Watershed in Tombstone, Arizona, which is also the location of the Soil Moisture Experiment in 2004 (SMEX04). The variability of radiometric temperature brightness data is also examined for its relationships to land surface parameters, climate variables, and insitu soil moisture measurements. Variability assessment is also evaluated for consistency and persistence over a three-year period.

  13. Mass loading of soil particles on plant surfaces

    SciTech Connect

    Pinder, J.E. III; McLeod, K.W. )

    1989-12-01

    Radionuclide-bearing soil particles on plant surfaces can be ingested and contribute to human dose, but evaluating the potential dose is limited by the relatively few data available on the masses of soil particles present on plant surfaces. This report summarizes mass loading data (i.e., mass of soil per unit of vegetation) for crops in the southeastern United States and compares these data to (1) those from other regions and (2) the mass loadings used in radionuclide transfer models to predict soil contamination of plant surfaces. Mass loadings were estimated using the 238Pu content of crops as an indicator of soil on plant surfaces. Crops were grown in two soils: a sandy clay loam soil and a loamy sand soil. Concentrations of soil on southeastern crops (i.e., mg soil g-1 plant) differed by more than a factor of 100 due to differences in crop growth form and biomass. Mean concentrations ranged from 1.7 mg g-1 for corn to 260 mg g-1 for lettuce. Differences in mass loadings between soils were less than those among crops. Concentrations differed by less than a factor of two between the two soil types. Because of (1) the differences among crops and (2) the limited data available from other systems, it is difficult to draw conclusions regarding regional or climatic variation in mass loadings. There is, however, little evidence to suggest large differences among regions. The mass loadings used to predict soil contamination in current radionuclide transfer models appear to be less than those observed for most crops.

  14. Reflectance anisotropy for characterising fine-scale changes in soil surface condition across different soil types

    NASA Astrophysics Data System (ADS)

    Croft, Holly; Anderson, Karen; Kuhn, Nikolaus J.

    2010-05-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in a reduction in soil productivity, an increased susceptibility to erosion and increased release of greenhouse gases. Soil surface roughness at the centimetre scale plays a fundamental role in affecting soil erosion and surface runoff pathways. A decline in surface roughness can also be used to infer soil degradation as soil aggregates are broken down through raindrop impact. However, due to the time and resources involved in using traditional field sampling techniques, there is a lack of spatially-distributed information on soil surface condition. Remotely sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Furthermore, a growing recognition into the importance of the directional reflectance domain has led to an increasing number of satellites with multiple view angle (MVA) capabilities (e.g. MISR, CHRIS on Proba). This is potentially useful for monitoring soil degradation and susceptibility to erosion because changes in soil surface roughness, associated with the breakdown of macro-aggregates, have a measurable effect on directional reflectance factors. Consequently, field and laboratory data are required for an empirical understanding of soil directional reflectance characteristics, underpinning subsequent model development. This study assessed the extent to which a hyperspectral MVA approach (350-2500 nm) could detect fine-scale changes in soil crusting states across five different soil types. A series of soil crusting states were produced for all five soil types, using an artificial rainfall simulator. The controlled conditions allowed the production of a series of stages in the soil crusting process; showing progressively declining surface roughness values. Each soil state was then spatially characterised, using a laboratory laser device at 2 mm sample spacing, over a 10 x 10 cm area. Laser data

  15. Visually assessing the level of development and soil surface stability of cyanobacterially dominated biological soil crusts

    USGS Publications Warehouse

    Belnap, J.; Phillips, S.L.; Witwicki, D.L.; Miller, M.E.

    2008-01-01

    Biological soil crusts (BSCs) are an integral part of dryland ecosystems and often included in long-term ecological monitoring programs. Estimating moss and lichen cover is fairly easy and non-destructive, but documenting cyanobacterial level of development (LOD) is more difficult. It requires sample collection for laboratory analysis, which causes soil surface disturbance. Assessing soil surface stability also requires surface disturbance. Here we present a visual technique to assess cyanobacterial LOD and soil surface stability. We define six development levels of cyanobacterially dominated soils based on soil surface darkness. We sampled chlorophyll a concentrations (the most common way of assessing cyanobacterial biomass), exopolysaccharide concentrations, and soil surface aggregate stability from representative areas of each LOD class. We found that, in the laboratory and field, LOD classes were effective at predicting chlorophyll a soil concentrations (R2=68-81%), exopolysaccharide concentrations (R2=71%), and soil aggregate stability (R2=77%). We took representative photos of these classes to construct a field guide. We then tested the ability of field crews to distinguish these classes and found this technique was highly repeatable among observers. We also discuss how to adjust this index for the different types of BSCs found in various dryland regions.

  16. Soil Surface Structure: A key factor for the degree of soil water repellency

    NASA Astrophysics Data System (ADS)

    Ahn, S.; Doerr, S. H.; Douglas, P.; Bryant, R.; Hamlett, C.; McHale, G.; Newton, M.; Shirtcliffe, N.

    2012-04-01

    Despite of considerable efforts, the degree of water repellency has not always been fully explained by chemical property of soil (termed hydrophobicity). That might be because the structure of a soil surface was not considered properly, which is another main factor determining the severity of soil water repellency. Surface structure has only recently been considered in soil science, whilst it has been paid attention for several decades in materials science due to its relevance to industrial applications. In this contribution, comparison of critical contact angles measured on different surface structures (made with glass beads, glass shards and beach sands) is presented and the effect of surface structure on manifestation of soil water repellency is discussed in terms of several different variables such as the individual particles shape, and areal and structural factors of the actual surface.

  17. First molecular detection of Leishmania infantum in Sergentomyia minuta (Diptera, Psychodidae) in Alentejo, southern Portugal.

    PubMed

    Pereira, S; Pita-Pereira, D; Araujo-Pereira, T; Britto, C; Costa-Rego, T; Ferrolho, J; Vilhena, M; Rangel, E F; Vilela, M L; Afonso, M O

    2017-10-01

    Protozoan parasites, such as Leishmania spp., are the causative agents of many insect-borne infectious diseases with medical and veterinary importance. Leishmaniasis, caused by Leishmania spp., is transmitted by female phlebotomine sand flies. In the Alentejo region of Portugal, located at the north of Algarve, cases of human and canine leishmaniasis caused by Leishmania infantum have been notified. However, no recent studies regarding the sand fly fauna in the region are available. We therefore aimed to explore the phlebotomine sand fly species found in both, Évora and Beja Districts, to gain an insight about the leishmaniasis epidemiology in these areas. After the identification of the insect species, PCR molecular tests were used to assess L. infantum infection rate in the sand fly captured females, together with the analysis of blood meal sources of the insect vectors. One Sergentomyia minuta female was positive for L. infantum infection and another for human blood as a meal source. The occurrence of this phlebotomine species infected with L. infantum may suggest that, in the Mediterranean basin, leishmaniasis epidemiology is changing. Also, if the importance of S. minuta for the zoonotic and anthroponotic cycle of leishmaniasis is later proven, the strategies to control its vector will inevitably to be rethought. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Liquid Spills on Permeable Soil Surfaces: Experimental Confirmations

    SciTech Connect

    Simmons, Carver S.; Keller, Jason M.

    2005-09-29

    Predictive tools for assessing the quantity of a spill on a soil from the observed spreading area could contribute to improving remediation when it is necessary. On a permeable soil, the visible spill area only hints about the amount of liquid that might reside below the surface. An understanding of the physical phenomena involved with spill propagation on a soil surface is key to assessing the liquid amount possibly present beneath the surface. The objective of this study is an improved prediction capability for spill behavior.

  19. Soil mineral surfaces of paddy soils are accessible for organic carbon accumulation after decalcification

    NASA Astrophysics Data System (ADS)

    Wissing, Livia

    2013-04-01

    We studied organic carbon (OC) accumulation due to organo-mineral associations during soil development on calcareous parent material. Two chronosequences in Zhejiang Province, PR China, were investigated; one under paddy cultivation with a maximum soil age of 2000 years, and the other under upland crops where the oldest soil was 700 years old. Bulk soils and soil fractions of the uppermost A horizons were analyzed for OC concentrations and radio carbon contents. Total pedogenic iron (Fed) concentration was determined by dithionite extraction and the proportion of oxalate extractable iron (Feox) was extracted by using the method of Schwertmann (1964). The specific surface area (SSA) of soil minerals was measured by the BET-N2 method (Brunauer et al., 1938) under four conditions: untreated, after organic matter removal, after iron removal and after removal of both. Within 700/2000 years of pedogenesis, we observed no change in clay mineral composition and no additional formation of the SSA of soil minerals. But the soils differed in the degree of decalcification, OC accumulation and in the formation of iron. Paddy soil management led to an enhanced decalcification and larger OC accumulation. Management-induced redox cycles caused larger proportions of Feox in paddy soils. Their large SSA, added to the surface area of clay minerals, provided additional options for OC covering. Unexpectedly, there was no evidence of formation of secondary minerals during soil development, which could provide new surfaces for OC accumulation. However, the study revealed higher OC coverings of mineral surfaces after decalcification in paddy soils. As carbonate and Ca2+ ions seemed to interconnect clay minerals, making their surface accessible to OC, the faster dissolution of carbonate and leaching of Ca2+ ions in paddy soils made additional clay mineral surfaces available to OC. In contrast, the surface area of minerals in non-paddy soils, in which decalcification was much lower, seemed

  20. [Fractal characteristics of soil particles in surface layer of black soil].

    PubMed

    Miao, Chi-Yuan; Wang, Ya-Feng; Wei, Xin; Xu, Xia; Shi, Wen

    2007-09-01

    Based on the second national soil survey of China, the fractal dimension of soil particles in the surface layers of 36 typical profiles of black soil was calculated. The results showed that the fractal dimension was 2.5831-2.8230, being increased with decreasing diameter of soil texture, but the variability was inconspicuous. The fractal dimension was negatively correlated with the contents of sand (2-0.02 mm) and silt (0.02-0.002 mm) (P < 0.05), but positively correlated with clay (< 0.002 mm) content (P < 0.01). No significant correlations were observed between soil particle fractal dimension and soil organic matter, total nitrogen, total phosphorus, total potassium, and pH. The fractal dimension of soil particles could be used as a comprehensive and quantitative index in evaluating the degradation degree of black soil.

  1. Wavelet-based detection of clods on a soil surface

    NASA Astrophysics Data System (ADS)

    Vannier, E.; Ciarletti, V.; Darboux, F.

    2009-11-01

    One of the aims of the tillage operation is to produce a specific range of clod sizes, suitable for plant emergence. Due to its cloddy structure, a tilled soil surface has its own roughness, which is connected also with soil water content and erosion phenomena. The comprehension and modeling of surface runoff and erosion require that the micro-topography of the soil surface is well estimated. Therefore, the present paper focuses on the soil surface analysis and characterization. An original method consisting in detecting the individual clods or large aggregates on a 3D digital elevation model (DEM) of the soil surface is introduced. A multiresolution decomposition of the surface is performed by wavelet transform. Then a supervised local maxima extraction is performed on the different sub surfaces and a last process makes the validation of the extractions and the merging of the different scales. The method of detection was evaluated with the help of a soil scientist on a controlled surface made in the laboratory as well as on real seedbed and ploughed surfaces, made by tillage operations in an agricultural field. The identifications of the clods are in good agreement, with an overall sensitivity of 84% and a specificity of 94%. The false positive or false negative detections may have several causes. Some very nearby clods may have been smoothed together in the approximation process. Other clods may be embedded into another peace of the surface relief such as another bigger clod or a part of the furrow. At last, the low levels of decomposition are dependent on the resolution and the measurement noise of the DEM. Therefore, some borders of clods may be difficult to determine. The wavelet-based detection method seems to be suitable for soil surfaces described by 2 or 3 levels of approximation such as seedbeds.

  2. Radar Mapping of Surface Soil Moisture

    NASA Technical Reports Server (NTRS)

    Ulaby, F. T.; Dubois, P. C.; van Zyl, J.

    1997-01-01

    Intended as an overview aimed at potential users of remotely sensed spatial distributions and temporal variations of soil moisture, this paper begins with an introductory section on the fundamentals of radar imaging and associated attributes.

  3. Infiltration in soils with a saturated surface

    NASA Astrophysics Data System (ADS)

    Hogarth, W. L.; Lockington, D. A.; Barry, D. A.; Parlange, M. B.; Haverkamp, R.; Parlange, J.-Y.

    2013-05-01

    An earlier infiltration equation relied on curve fitting of infiltration data for the determination of one of the parameters, which limits its usefulness in practice. This handicap is removed here, and the parameter is now evaluated by linking it directly to soil-water properties. The new predictions of infiltration using this evaluation are quite accurate. Positions and shapes of soil-water profiles are also examined in detail and found to be predicted analytically with great precision.

  4. SMAP Level 4 Surface and Root Zone Soil Moisture

    NASA Technical Reports Server (NTRS)

    Reichle, R.; De Lannoy, G.; Liu, Q.; Ardizzone, J.; Kimball, J.; Koster, R.

    2017-01-01

    The SMAP Level 4 soil moisture (L4_SM) product provides global estimates of surface and root zone soil moisture, along with other land surface variables and their error estimates. These estimates are obtained through assimilation of SMAP brightness temperature observations into the Goddard Earth Observing System (GEOS-5) land surface model. The L4_SM product is provided at 9 km spatial and 3-hourly temporal resolution and with about 2.5 day latency. The soil moisture and temperature estimates in the L4_SM product are validated against in situ observations. The L4_SM product meets the required target uncertainty of 0.04 m(exp. 3)m(exp. -3), measured in terms of unbiased root-mean-square-error, for both surface and root zone soil moisture.

  5. Quantification of chemical transport processes from soil to surface runoff

    USDA-ARS?s Scientific Manuscript database

    Although there is a conceptual understanding on processes governing chemical transport from soil to surface runoff, there are little literature and research results actually quantifying these individual processes. We developed a laboratory flow cell and experimental procedures to quantify chemical ...

  6. A Methodology for Soil Moisture Retrieval from Land Surface Temperature, Vegetation Index, Topography and Soil Type

    NASA Astrophysics Data System (ADS)

    Pradhan, N. R.

    2015-12-01

    Soil moisture conditions have an impact upon hydrological processes, biological and biogeochemical processes, eco-hydrology, floods and droughts due to changing climate, near-surface atmospheric conditions and the partition of incoming solar and long-wave radiation between sensible and latent heat fluxes. Hence, soil moisture conditions virtually effect on all aspects of engineering / military engineering activities such as operational mobility, detection of landmines and unexploded ordinance, natural material penetration/excavation, peaking factor analysis in dam design etc. Like other natural systems, soil moisture pattern can vary from completely disorganized (disordered, random) to highly organized. To understand this varying soil moisture pattern, this research utilized topographic wetness index from digital elevation models (DEM) along with vegetation index from remotely sensed measurements in red and near-infrared bands, as well as land surface temperature (LST) in the thermal infrared bands. This research developed a methodology to relate a combined index from DEM, LST and vegetation index with the physical soil moisture properties of soil types and the degree of saturation. The advantage in using this relationship is twofold: first it retrieves soil moisture content at the scale of soil data resolution even though the derived indexes are in a coarse resolution, and secondly the derived soil moisture distribution represents both organized and disorganized patterns of actual soil moisture. The derived soil moisture is used in driving the hydrological model simulations of runoff, sediment and nutrients.

  7. Soil and surface runoff phosphorus relationships for five typical USA midwest soils.

    PubMed

    Allen, B L; Mallarino, A P; Klatt, J G; Baker, J L; Camara, M

    2006-01-01

    Excessively high soil P can increase P loss with surface runoff. This study used indoor rainfall simulations to characterize soil and runoff P relationships for five Midwest soils (Argiudoll, Calciaquaoll, Hapludalf, and two Hapludolls). Topsoil (15-cm depth, 241-289 g clay kg(-1) and pH 6.0-8.0) was incubated with five NH4H2PO4 rates (0-600 mg P kg(-1)) for 30 d. Total soil P (TPS) and soil-test P (STP) measured with Bray-P1 (BP), Mehlich-3 (M3P), Olsen (OP), Fe-oxide-impregnated paper (FeP), and water (WP) tests were 370 to 1360, 3 to 530, 10 to 675, 4 to 640, 7 to 507, and 2 to 568 mg P kg(-1), respectively. Degree of soil P saturation (DPS) was estimated by indices based on P sorption index (PSI) and STP (DPSSTP) and P, Fe, and Al extracted by ammonium oxalate (DPSox) or Mehlich-3 (DPSM3). Soil was packed to 1.1 g cm(-3) bulk density in triplicate boxes set at 4% slope. Surface runoff was collected during 75 min of 6.5 cm h(-1) rain. Runoff bioavailable P (BAP) and dissolved reactive P (DRP) increased linearly with increased P rate, STP, DPSox, and DPSM3 but curvilinearly with DPSSTP. Correlations between DRP or BAP and soil tests or saturation indices across soils were greatest (r > or = 0.95) for FeP, OP, and WP and poorest for BP and TPS (r = 0.83-0.88). Excluding the calcareous soil (Calciaquoll) significantly improved correlations only for BP. Differences in relationships between runoff P and the soil tests were small or nonexistent among the noncalcareous soils. Routine soil P tests can estimate relationships between runoff P concentration and P application or soil P, although estimates would be improved by separate calibrations for calcareous and noncalcareous soils.

  8. Unraveling the size distributions of surface properties for purple soil and yellow soil.

    PubMed

    Tang, Ying; Li, Hang; Liu, Xinmin; Zhu, Hualing; Tian, Rui

    2015-06-01

    Soils contain diverse colloidal particles whose properties are pertinent to ecological and human health, whereas few investigations systematically analyze the surface properties of these particles. The objective of this study was to elucidate the surface properties of particles within targeted size ranges (i.e. >10, 1-10, 0.5-1, 0.2-0.5 and <0.2 μm) for a purple soil (Entisol) and a yellow soil (Ultisol) using the combined determination method. The mineralogy of corresponding particle-size fractions was determined by X-ray diffraction. We found that up to 80% of the specific surface area and 85% of the surface charge of the entire soil came from colloidal-sized particles (<1 μm), and almost half of the specific surface area and surface charge came from the smallest particles (<0.2 μm). Vermiculite, illite, montmorillonite and mica dominated in the colloidal-sized particles, of which the smallest particles had the highest proportion of vermiculite and montmorillonite. For a given size fraction, the purple soil had a larger specific surface area, stronger electrostatic field, and higher surface charge than the yellow soil due to differences in mineralogy. Likewise, the differences in surface properties among the various particle-size fractions can also be ascribed to mineralogy. Our results indicated that soil surface properties were essentially determined by the colloidal-sized particles, and the <0.2 μm nanoparticles made the largest contribution to soil properties. The composition of clay minerals within the diverse particle-size fractions could fully explain the size distributions of surface properties.

  9. Surface features of soil particles of three types of soils under different land use strategies

    NASA Astrophysics Data System (ADS)

    Matveeva, Nataliy; Kotelnikova, Anna; Rogova, Olga; Proskurnin, Mikhail

    2017-04-01

    Nowadays, there is a clear need in a deep investigation of molecular composition of soils and of its influence on surface characteristics of soil particles. The aim of this study is to evaluate the composition and properties of physical fractions in different soil types in determining functional specificity of soil solid-phase surface. The experiments were carried out with three different types of Russian soils—Sod-Podzolic, Chestnut, and Chernozem soils—under various treatments (fallow, different doses of mineral fertilizers and their aftereffects). The samples were separated into three fractions: silt (SF) with a particle size of <2 μm, light fraction (LF) with a density of <2 g/cm3, and residual fraction (RF) with a size >2 μm and the density >2 g/cm3. We measured specific surface area, surface hydrophobicity (contact angle, CA), ζ-potential, and the point of zero charge (PZC). For Chernozem and Chestnut soils and their fractions of we observed an increase in hydrophobicity for SF and RF under fertilizer treatment. At the sites not treated with fertilizers and aftereffect sites, the hydrophobicity of fractions was lower compared to the sites under treatment. The CA of the original soils and fractions were different: in 35% of cases CA was higher for SF and RF by 12-16%. The rest of samples demonstrated CA of all three physical fractions lower than CA of the original soil. The variability of the mean CA indicates considerable differences in ζ-potential and PZC between different types of soils and soil fractions. The results of potentiometric titration of PZC for Sod-Podzolic soil showed that all values are in acidic range, which suggests predominance of acidic functional groups at the surface of soil particles. Specific surface area determines soil sorption processes, bioavailability of nutrients, water etc. Here, specific surface area of Sod-Podzolic soil was low and SF-dependent. We calculated specific surface charge from obtained data on specific

  10. Surface history of some Apollo 17 lunar soils

    NASA Technical Reports Server (NTRS)

    Fleischer, R. L.; Hart, H. R., Jr.

    1974-01-01

    Cosmic ray track densities in Apollo 17 soil samples are used to infer surface exposure times of soils from a trench at Van Serg Crater, from on and near a boulder at Camelot Crater, and from the position of the heat flow and neutron flux experiments (the ALSEP site). The topmost 2 cm of soil at Van Serg was exposed for 11 m.y., the top cm at Camelot for 36 m.y. A layering chronology and average deposition rate are proposed for the trench. For all soils the median track densities imply predispositional irradiation in the top 15 cm of the lunar surface for times that were long compared with the actual residence in the stratigraphic positions from which the soils were collected. Van Serg crater is inferred to have been formed approximately 24 m.y. ago.

  11. Soil Moisture: The Hydrologic Interface Between Surface and Ground Waters

    NASA Technical Reports Server (NTRS)

    Engman, Edwin T.

    1997-01-01

    A hypothesis is presented that many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture. The specific hydrologic processes that may be detected include groundwater recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential evapotranspiration (ET), and information about the hydrologic properties of soils. In basin and hillslope hydrology, soil moisture is the interface between surface and ground waters.

  12. Soil Moisture: The Hydrologic Interface Between Surface and Ground Waters

    NASA Technical Reports Server (NTRS)

    Engman, Edwin T.

    1997-01-01

    A hypothesis is presented that many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture. The specific hydrologic processes that may be detected include groundwater recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential evapotranspiration (ET), and information about the hydrologic properties of soils. In basin and hillslope hydrology, soil moisture is the interface between surface and ground waters.

  13. Soil moisture from temperature measurements at the Earth's surface, update

    NASA Technical Reports Server (NTRS)

    Welker, J. E.

    1984-01-01

    Soil moisture budgets at the Earth's surface were investigated based on soil and atmospheric temperature variations. A number of data sets were plotted and statistically analyzed in order to accentuate the existence and the characteristics of mesoscale soil temperature extrema variations and their relations to other parameters. The correlations between diurnal temperature extrema for air and soil in drought and non-drought periods appear to follow different characteristic patterns, allowing an inference of soil moisture content from temperature data. The recovery of temperature extrema after a precipitation event also follows a characteristic power curve rise between two limiting values which is an indicator of evaporation rates. If these indicators are applied universally to regional temperature data, soil moisture content or drought conditions can be inferred directly from temperature measurements.

  14. Soil moisture from temperature measurements at the Earth's surface, update

    NASA Technical Reports Server (NTRS)

    Welker, J. E.

    1984-01-01

    Soil moisture budgets at the Earth's surface were investigated based on soil and atmospheric temperature variations. A number of data sets were plotted and statistically analyzed in order to accentuate the existence and the characteristics of mesoscale soil temperature extrema variations and their relations to other parameters. The correlations between diurnal temperature extrema for air and soil in drought and non-drought periods appear to follow different characteristic patterns, allowing an inference of soil moisture content from temperature data. The recovery of temperature extrema after a precipitation event also follows a characteristic power curve rise between two limiting values which is an indicator of evaporation rates. If these indicators are applied universally to regional temperature data, soil moisture content or drought conditions can be inferred directly from temperature measurements.

  15. Characterization of surface soils at a former uranium mill.

    PubMed

    Johnson, J A; Meyer, H R; Vidyasagar, M

    2006-02-01

    Dawn Mining Company operated a uranium mill in Stevens County, Washington, from 1957 to 1982, to process ore from the Midnite Mine, and from 1992 through 2000, to extract uranium from mine water treatment sludge. The mill was permanently shut down in 2001 when the Dawn Mining Company radioactive materials license was amended to allow direct disposal of water treatment sludge to a tailings disposal area at the mill. The mill building was demolished in 2003. Site soil characterization took place in 2004. Soil cleanup is ongoing. Contaminated soils on the site were characterized using a GPS-based gamma scanning system. A correlation between shielded gamma exposure rate and concentration of Ra in surface soils was developed. Subsurface soils were sampled using backhoe trenches. This system proved efficient and accurate in guiding development of the remedial action planning for the site and subsequent soil cleanup.

  16. Control of Eolian soil erosion from waste site surface barriers

    SciTech Connect

    Ligotke, M.W.

    1994-11-01

    Physical models were tested in a wind tunnel to determine optimum surface-ravel admixtures for protecting silt-loam soil from erosion by, wind and saltating, sand stresses. The tests were performed to support the development of a natural-material surface barrier for and waste sites. Plans call for a 2-m deep silt-loam soil reservoir to retain infiltrating water from rainfall and snowmelt. The objective of the study was to develop a gravel admixture that would produce an erosion-resistant surface layer during, periods of extended dry climatic stress. Thus, tests were performed using simulated surfaces representing dry, unvegetated conditions present just after construction, after a wildfire, or during an extended drought. Surfaces were prepared using silt-loam soil mixed with various grades of sand and Travel. Wind-induced surface shear stresses were controlled over the test surfaces, as were saltating, sand mass flow rates and intensities. Tests were performed at wind speeds that approximated and exceeded local 100-year peak gust intensities. Surface armors produced by pea gravel admixtures were shown to provide the best protection from wind and saltating sand stresses. Compared with unprotected silt-loam surfaces, armored surfaces reduced erosion rates by more than 96%. Based in part on wind tunnel results, a pea gravel admixture of 15% will be added to the top 1 in of soil in a prototype barrier under construction in 1994. Field tests are planned at the prototype site to provide data for comparison with wind tunnel results.

  17. Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings

    NASA Technical Reports Server (NTRS)

    Cuddihy, E. F.; Willis, P. B.

    1984-01-01

    Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented.

  18. How surface roughness affects chemical transfer from soil to surface runoff?

    USDA-ARS?s Scientific Manuscript database

    Soil surface roughness affects transport processes, e.g., runoff generation, infiltration, sediment detachment, etc., occurring on the surface. Nevertheless, how soil roughness affects chemical transport is less known. In this study, we partitioned roughness elements into mounds which diverge water ...

  19. Surface Roughness Effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

    USDA-ARS?s Scientific Manuscript database

    Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss, yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt ...

  20. Surface Roughness effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

    USDA-ARS?s Scientific Manuscript database

    Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt l...

  1. Soil surface disturbances in cold deserts: Effects on nitrogenase activity in cyanobacterial-lichen soil crusts

    USGS Publications Warehouse

    Belnap, Jayne

    1996-01-01

    CyanobacteriaMichen soil crusts can be a dominant source of nitrogen for cold-desert ecosystems. Effects of surface disturbance from footprints, bike and vehicle tracks on the nitrogenase activity in these crusts was investigated. Surface disturbances reduced nitrogenase activity by 30-100%. Crusts dominated by the cyanobacterium Microcoleus vaginatus on sandy soils were the most susceptible to disruption; crusts on gypsiferous soils were the least susceptible. Crusts where the soil lichen Collema tenax was present showed less immediate effects; however, nitrogenase activity still declined over time. Levels of nitrogenase activity reduction were affected by the degree of soil disruption and whether sites were dominated by cyanobacteria with or without heterocysts. Consequently, anthropogenic surface disturbances may have serious implications for nitrogen budgets in these ecosystems.

  2. Estimating Surface Soil Moisture in Simulated AVIRIS Spectra

    NASA Technical Reports Server (NTRS)

    Whiting, Michael L.; Li, Lin; Ustin, Susan L.

    2004-01-01

    Soil albedo is influenced by many physical and chemical constituents, with moisture being the most influential on the spectra general shape and albedo (Stoner and Baumgardner, 1981). Without moisture, the intrinsic or matrix reflectance of dissimilar soils varies widely due to differences in surface roughness, particle and aggregate sizes, mineral types, including salts, and organic matter contents. The influence of moisture on soil reflectance can be isolated by comparing similar soils in a study of the effects that small differences in moisture content have on reflectance. However, without prior knowledge of the soil physical and chemical constituents within every pixel, it is nearly impossible to accurately attribute the reflectance variability in an image to moisture or to differences in the physical and chemical constituents in the soil. The effect of moisture on the spectra must be eliminated to use hyperspectral imagery for determining minerals and organic matter abundances of bare agricultural soils. Accurate soil mineral and organic matter abundance maps from air- and space-borne imagery can improve GIS models for precision farming prescription, and managing irrigation and salinity. Better models of soil moisture and reflectance will also improve the selection of soil endmembers for spectral mixture analysis.

  3. Spectral reflectance of surface soils: Relationships with some soil properties

    NASA Technical Reports Server (NTRS)

    Kiesewetter, C. H.

    1983-01-01

    Using a published atlas of reflectance curves and physicochemical properties of soils, a statistical analysis was carried out. Reflectance bands which correspond to five of the wavebands used by NASA's Thematic Mapper were examined for relationships to specific soil properties. The properties considered in this study include: Sand Content, Silt Content, Clay Content, Organic Matter Content, Cation Exchange Capacity, Iron Oxide Content and Moisture Content. Regression of these seven properties on the mean values of five TM bands produced results that indicate that the predictability of the properties can be increased by stratifying the data. The data was stratified by parent material, taxonomic order, temperature zone, moisture zone and climate (combined temperature and moisture). The best results were obtained when the sample was examined by climatic classes. The middle Infra-red bands, 5 and 7, as well as the visible bands, 2 and 3, are significant in the model. The near Infra-red band, band 4, is almost as useful and should be included in any studies. General linear modeling procedures examined relationships of the seven properties with certain wavebands in the stratified samples.

  4. Spatial and temporal variability of soil temperature, moisture and surface soil properties

    NASA Technical Reports Server (NTRS)

    Hajek, B. F.; Dane, J. H.

    1993-01-01

    The overall objectives of this research were to: (l) Relate in-situ measured soil-water content and temperature profiles to remotely sensed surface soil-water and temperature conditions; to model simultaneous heat and water movement for spatially and temporally changing soil conditions; (2) Determine the spatial and temporal variability of surface soil properties affecting emissivity, reflectance, and material and energy flux across the soil surface. This will include physical, chemical, and mineralogical characteristics of primary soil components and aggregate systems; and (3) Develop surface soil classes of naturally occurring and distributed soil property assemblages and group classes to be tested with respect to water content, emissivity and reflectivity. This document is a report of studies conducted during the period funded by NASA grants. The project was designed to be conducted over a five year period. Since funding was discontinued after three years, some of the research started was not completed. Additional publications are planned whenever funding can be obtained to finalize data analysis for both the arid and humid locations.

  5. Influence of surface crusting on infiltration of a loess plateau soil

    USDA-ARS?s Scientific Manuscript database

    Surface sealing and crusting are common widespread processes that occur in many cultivated soils worldwide, especially in arid and semiarid regions. Soil crusting negatively affects water infiltration, increases surface runoff, reduces seedling emergence, restricts air exchange between the soil and ...

  6. Predicting root zone soil moisture using surface data

    NASA Astrophysics Data System (ADS)

    Manfreda, S.; Brocca, L.; Moramarco, T.; Melone, F.; Sheffield, J.; Fiorentino, M.

    2012-04-01

    In recent years, much effort has been given to monitoring of soil moisture from satellite remote sensing. These tools represent an extraordinary source of information for hydrological applications, but they only provide information on near-surface soil moisture. In the present work, we developed a new formulation for the estimation of the soil moisture in the root zone based on the measured value of soil moisture at the surface. The method derives from a simplified form of the soil water balance equation and for this reason all parameters adopted are physically consistent. The formulation provides a closed form of the relationship between the root zone soil moisture and the surface soil moisture with a limited number of parameters, such as: the ratio between the depth of the surface layer and the deeper layer, the water loss coefficient, and the field capacity. The method has been tested using modeled soil moisture obtained from the North American Land Data Assimilation System (NLDAS). The NLDAS is a multi-institution partnership aimed at developing a retrospective data set, using available atmospheric and land surface meteorological observations to compute the land surface hydrological budget. The NLDAS database was extremely useful for the scope of the present research since it provides simulated data over an extended area with different climatic and physical condition and moreover it provides soil moisture data averaged over different depths. In particular, we used values in the top 10 cm and 100 cm layers. One year of simulation was used to test the ability of the developed method to describe soil moisture fluctuation in the 100cm layer over the entire NLDAS domain. The method was adopted by calibrating one of its three parameters and defining the remaining two based on physical characteristics of the site (using the potential evapotranspiration and ratio between the first and the second soil layer depth). In general, the method performed better than

  7. Effects of soil surface components on soil hydrological behaviour in a dry Mediterranean environment (Southern Spain)

    NASA Astrophysics Data System (ADS)

    Ruiz Sinoga, Jose Damian; Martinez Murillo, Juan Francisco

    2009-07-01

    Various researchers have studied the spatial pattern of soil surface components such as vegetation, rock fragments, bare soil, litter and surface crusts, as a key factor of hydrological behaviour in Mediterranean settings with heterogeneous patches of vegetation cover and strong human impact. The studies indicate that there is a mosaic of patches that generate run-off or infiltrate overland flow, distributed in various ways along hillslopes. Few of these studies, however, have looked at areas underlain by metamorphic rocks such as phyllites or schists. This study analysed the temporal and spatial variability of the effects of soil surface components on hydrological processes in a small dry Mediterranean catchment underlain by metamorphic rocks. A systematic sampling of multiple sites throughout a hydrological year was carried out. We related the hydrological behaviour of soil surface components to 1) their position along the hillslope, 2) the distance of existing vegetation tussocks from the line of run-off, 3) rainfall intensity and 4) the main physical/chemical soil properties affecting infiltration processes. Statistical analysis was used to check the validity of the relationships. The results show that soil surface components have highly variable effects, in both space and time, on soil hydrological behaviour. These effects particularly depend on the location along the line of maximum slope and the intensity of preceding rainfall, whose interaction defines soil hydrological status. These results are similar to those for other Mediterranean settings with different lithology, in that the succession of contributing patches are hydrologically interconnected along a hillslope. The variables used and the grouping of explanatory variables through principal component analyses were found to be suitable for discussing the spatial distribution of soil surface components in the hydrologically dynamic environment of the study area.

  8. Novel Measurement and Monitoring Approaches for Surface and Near-Surface Soil Moisture

    NASA Astrophysics Data System (ADS)

    Jones, S. B.; Sheng, W.; Zhou, R.; Sadeghi, M.; Tuller, M.

    2015-12-01

    The top inch of the earth's soil surface is a very dynamic and important layer where physical and biogeochemical processes take place under extreme diurnal and seasonal moisture and temperature variations. Some of these critical surfaces include biocrusts, desert pavements, agricultural lands, mine tailings, hydrophobic forest soils, all of which can significantly impact environmental conditions at large-scales. Natural hazards associated with surface conditions include dust storms, post-fire erosion and flooding in addition to crop failure. Less obvious, though continually occurring, are microbial-induced gas emissions that are also significantly impacted by surface conditions. With so much at stake, it is surprising that in today's technological world there are few if any sensors designed for monitoring the top few mm or cm of the soil surface. In particular, remotely sensed data is expected to provide near-real time surface conditions of our Earth, but we lack effective tools to measure and calibrate surface soil moisture. We are developing multiple methods for measurement and monitoring of surface and near-surface soil water content which include gravimetric as well as electromagnetic approaches. These novel measurement solutions and their prospects to improve soil surface water content determination will be presented.

  9. Photodegradation of bensulfuron-methyl on soil surface.

    PubMed

    Si, You-Bin; Yue, Yong-De; Chen, Huai-Man; Zhou, Dong-Mei

    2004-03-01

    Photolysis of bensulfuron-methyl on soil surface was studied under sunlight and UV light. Seven photoproducts were isolated and characterised by spectroscopic methods. The major processes in the photolysis of bensulfuron-methyl in soil are cleavage of the sulfonylurea bridge, scission of the SO2NH bond and contraction of the sulfuronylurea bridge. The rates of photodegradation of bensulfuron-methyl on different soils followed first-order rate kinetics with half lives of 21.9, 28.4, 36.9, 59.2 and 47.2 h (UV) and 23.1, 27.5, 29.1, 38.9 and 33.8 days (sunlight) for vertisol, alluvial, alfisol, red and laterite soils, respectively. The differences in rates of photodegradation were dependent upon the soil texture and organic matter content.

  10. Restoring the natural state of the soil surface by biocrusts

    NASA Astrophysics Data System (ADS)

    Zaady, Eli; Ungar, Eugene D.; Stavi, Ilan; Shuker, Shimshon; Knoll, Yaakov M.

    2017-04-01

    In arid and semi-arid areas, with mean annual precipitation of 70-200 mm, the dominant component of the ground cover is biocrusts composed of cyanobacteria, moss and lichens. Biocrusts play a role in stabilizing the soil surface, which reduces erosion by water and wind. Human disturbances, such as heavy vehicular traffic, earthworks, overgrazing and land mining destroy the soil surface and promote erosion. The aim of the study was to evaluate restoration of the soil surface by the return of a biocrust layer. We examined the impact of disturbances on the creation of a stable crust and on the rate of recovery. Biocrust disturbance was studied in two sites in the northern Negev. The nine treatments included different rates of biocrust inoculum application and NPK fertilization. Recovery rates of the biocrusts were monitored for five years using chemical, physical and bio-physiological tests which determined infiltration rate, soil surface resistance to pressure, shear force of the soil surface, levels of chlorophyll, organic matter and polysaccharide, NDVI and aggregate stability. The results show that untreated disturbed biocrusts present long-term damage and a very slow rate of recovery, which may take decades, while most of the treatments showed a faster recovery. In particular, NDVI, polysaccharide levels and aggregate stability showed steady improvements over the research period.

  11. Soil Surface Composition Effects on the Wettability of Aquifer Materials

    NASA Astrophysics Data System (ADS)

    Ryder, J. L.; Demond, A. H.

    2004-05-01

    The wettability of subsurface porous media is critical for determining the distribution of non-aqueous phase liquids. Variations in the wettability of subsurface materials are generally attributed to sorption of hydrophobic contaminants. However, naturally occurring carbonaceous materials may influence the wettability as well. A series of seven soil materials were selected to determine the effect of organic carbon surfaces on soil wetting behavior. The materials represent organic carbon containing surfaces that may be found in soils from young humic matter to mature coal and shale kerogen. Measurements of organic liquid-water contact angle against cut rock faces reveal that surface composition alters the contact angle from the completely water wetted condition of quartz in the case of the mature carbon materials (Lachine Shale, Garfield Shale, Waynesburg Coal, and Plumbago Mineral Carbon). An examination of the soil elemental composition confirms that the bulk elemental composition of each material is separated on a plot of hydrogen to carbon versus oxygen to carbon ratios. The functional groups present at the surface of the soil materials were obtained with Fourier Transform Infrared Spectroscopy (FT-IR) analysis and indicate that the presence of oxygen containing surface functional groups is positively correlated with increased organic-liquid wetting. This study demonstrates that even in the absence of sorbing contaminants the subsurface is fractionally water-wet. This finding may help explain why subsurface distributions of non aqueous phase liquids can vary from those determined with laboratory sands.

  12. Soil-soil solution distribution coefficient of soil organic matter is a key factor for that of radioiodide in surface and subsurface soils.

    PubMed

    Unno, Yusuke; Tsukada, Hirofumi; Takeda, Akira; Takaku, Yuichi; Hisamatsu, Shun'ichi

    2017-04-01

    We investigated the vertical distribution of the soil-soil-solution distribution coefficients (Kd) of (125)I, (137)Cs, and (85)Sr in organic-rich surface soil and organic-poor subsurface soil of a pasture and an urban forest near a spent-nuclear-fuel reprocessing plant in Rokkasho, Japan. Kd of (137)Cs was highly correlated with water-extractable K(+). Kd of (85)Sr was highly correlated with water-extractable Ca(2+) and SOC. Kd of (125)I(-) was low in organic-rich surface soil, high slightly below the surface, and lowest in the deepest soil. This kinked distribution pattern differed from the gradual decrease of the other radionuclides. The thickness of the high-(125)I(-)Kd middle layer (i.e., with high radioiodide retention ability) differed between sites. Kd of (125)I(-) was significantly correlated with Kd of soil organic carbon. Our results also showed that the layer thickness is controlled by the ratio of Kd-OC between surface and subsurface soils. This finding suggests that the addition of SOC might prevent further radioiodide migration down the soil profile. As far as we know, this is the first report to show a strong correlation of a soil characteristic with Kd of (125)I(-). Further study is needed to clarify how radioiodide is retained and migrates in soil.

  13. Forest Management Effects on Surface Soil Carbon and Nitrogen

    Treesearch

    Jennifer D. Knoepp; Wayne T. Swank

    1997-01-01

    Changes in surface soil C and N can result from forest management practices and may provide an index of impacts on long-term site productivity. Soil C and N were measured over time for five water- sheds in the southern Appalachians: two aggrading hardwood forests, one south- and one north-facing, undisturbed since the 1920s;a white pine (PinussfrobusL.) plantation...

  14. Mapping soil moisture and surface heat fluxes by assimilating GOES land surface temperature and SMAP soil moisture data

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Steele-Dunne, Susan C.; van de Giesen, Nick

    2017-04-01

    This study is focused on estimating soil moisture and sensible/latent heat fluxes by assimilating remotely-sensed land surface temperature (LST) and soil moisture data. Surface heat fluxes interact with the overlying atmosphere, and play a crucial role in the water and energy cycles. However, they cannot be directly measured using remote sensing. It has been demonstrated that LST time series contain information about the surface energy balance, and that assimilating soil moisture further improves the estimation by putting more constraints on the energy partitioning. In previous studies, two controlling factors were estimated: (1) a monthly constant bulk heat transfer coefficient (CHN) that scales the sum of surface heat fluxes, and (2) an evaporative fraction (EF) which governs the energy partitioning and stays quasi-constant during the near-peak hours. Considering the fact that CHN is not constant especially in the growing season, here CHN is assumed a function of leaf area index (LAI). LST data from GOES (Geostationary Operational Environmental Satellites) and soil moisture data from SMAP (Soil Moisture Active Passive) are both assimilated into a simply heat and water transfer model to update LST, soil moisture, CHN and EF , and to map surface heat fluxes over a study area in central US. A hybrid data assimilation strategy is necessary because SMAP data are available every 2-3 days, while GOES LST data are provided every hour. In this study, LST data are assimilated using an adaptive particle batch smoother (APBS) and soil moisture is periodically updated using a particle filter (PF). Results show that soil moisture is greatly improved, and that EF estimates are restored very well after assimilation. As forcing data are provided by remote sensing or reanalysis products to minimize the dependence on ground measurements, this methodology can be easily applied in other regions with limited data.

  15. Rhamnolipid surface thermodynamic properties and transport in agricultural soil.

    PubMed

    Renfro, Tyler Dillard; Xie, Weijie; Yang, Guang; Chen, Gang

    2014-03-01

    Rhamnolipid is a biosurfactant produced by several Pseudomonas species, which can wet hydrophobic soils by lowering the cohesive and/or adhesive surface tension. Because of its biodegradability, rhamnolipid applications bring minimal adverse impact on the soil and groundwater as compared with that of chemical wetting agents. Subsequently, rhamnolipid applications have more advantages when used to improve irrigation in the agricultural soil, especially under draught conditions. In the presence of rhamnolipid, water surface tension dropped linearly with the increase of rhamnolipid concentration until the rhamnolipid critical micelle concentration (CMC) of 30 mg/L was reached. Below the CMC, rhamnolipid had linear adsorption isotherms on the soil with a partition coefficient of 0.126 L/kg. Rhamnolipid transport breakthrough curves had a broad and diffuse infiltration front, indicating retention of rhamnolipid on the soil increased with time. Rhamnolipid transport was found to be well represented by the advection-dispersion equation based on a local equilibrium assumption. When applied at concentrations above the CMC, the formed rhamnolipid micelles prevented rhamnolipid adsorption (both equilibrium adsorption and kinetic adsorption) in the soil. It was discovered in this research that rhamnolipid surface thermodynamic properties played the key role in controlling rhamnolipid transport. The attractive forces between rhamnolipid molecules contributed to micelle formation and facilitated rhamnolipid transport.

  16. Soil surface roughness and porosity under different tillage systems

    NASA Astrophysics Data System (ADS)

    Rodriguez-Gonzalez, J.; Saa-Requejo, A.; Gómez, J. A.; Valencia, J. L.; Zarco, P.; Tarquis, A. M.

    2012-04-01

    Both soil porosity and surface elevation can be altered by tillage operation. Even though the surface porosity is an important parameter of a tilled field, however, no practical technique for rapid and non-contact measurement of surface porosity has been developed yet. On the contrary, the surface elevation of tilled soil can be quickly determined with a laser profiler. Working under the assumption that the surface elevation of a tilled field is a complicated superposition of the soil terrain profile at a larger-scale and the roughness at a fine-scale, this study included three aspects: (i) to establish an index (Roughness Index, RI) at a fine-scale to associate the surface roughness with porosity; (ii) to examine the correlation between surface porosity and the proposed RI by three types of tillage treatment in the field; and (iii) to check the scaling/multiscaling behavior among different grid sizes of calculating RI on predicting surface porosity. Consequently, the statistical results from each tilled plot show a strong correlation between the surface porosity and the defined RI in an early stage (ca. 2 days) after tillage. Acknowledgements Funding provided by CEIGRAM (Research Centre for the Management of Agricultural and Environmental Risks)and Spanish Ministerio de Ciencia e Innovación (MICINN) through project AGL2010-21501/AGR is greatly appreciated.

  17. Automatic Earthquake Detection and Location by Waveform coherency in Alentejo (South Portugal) Using CatchPy

    NASA Astrophysics Data System (ADS)

    Custodio, S.; Matos, C.; Grigoli, F.; Cesca, S.; Heimann, S.; Rio, I.

    2015-12-01

    Seismic data processing is currently undergoing a step change, benefitting from high-volume datasets and advanced computer power. In the last decade, a permanent seismic network of 30 broadband stations, complemented by dense temporary deployments, covered mainland Portugal. This outstanding regional coverage currently enables the computation of a high-resolution image of the seismicity of Portugal, which contributes to fitting together the pieces of the regional seismo-tectonic puzzle. Although traditional manual inspections are valuable to refine automatic results they are impracticable with the big data volumes now available. When conducted alone they are also less objective since the criteria is defined by the analyst. In this work we present CatchPy, a scanning algorithm to detect earthquakes in continuous datasets. Our main goal is to implement an automatic earthquake detection and location routine in order to have a tool to quickly process large data sets, while at the same time detecting low magnitude earthquakes (i.e. lowering the detection threshold). CatchPY is designed to produce an event database that could be easily located using existing location codes (e.g.: Grigoli et al. 2013, 2014). We use CatchPy to perform automatic detection and location of earthquakes that occurred in Alentejo region (South Portugal), taking advantage of a dense seismic network deployed in the region for two years during the DOCTAR experiment. Results show that our automatic procedure is particularly suitable for small aperture networks. The event detection is performed by continuously computing the short-term-average/long-term-average of two different characteristic functions (CFs). For the P phases we used a CF based on the vertical energy trace while for S phases we used a CF based on the maximum eigenvalue of the instantaneous covariance matrix (Vidale 1991). Seismic event location is performed by waveform coherence analysis, scanning different hypocentral coordinates

  18. Characterising soil surface roughness with a frequency modulated polarimetric radar

    NASA Astrophysics Data System (ADS)

    Seeger, Manuel; Gronz, Oliver; Beiske, Joshua; Klein, Tobias

    2014-05-01

    Soil surface roughness is considered crucial for soil erosion as it determines the effective surface exposed to the raindrop impact. It regulates surface runoff velocity and it causes runoff concentration. But a comprehensive characterisation of the shape of the soils' surface is still difficult to achieve. Photographic systems and terrestrial laser-scanning are nowadays able to generate high resolution DEMs, but the derivation of roughness parameters is still not clear. Spaceborne radar systems are used for about 3 decades for earth survey. Spatial soil moisture distribution, ice sheet monitoring and earth-wide topographic survey are the main objectives of these radar systems, working generally with frequencies <10 GHz. Contrasting with this, technologies emitting frequencies up to 77 GHz are generally used for object tracking purposes. But it is known, that the reflection characteristics, such as intensity and polarisation, strongly depend on the properties of the target object. A new design of a frequency modulated continuous wave radar, emitting a right hand shaped circular polarization and receiving both polarization directions, right and left-hand shaped, is tested here for its ability to detect and quantify different surface roughness. The reflection characteristics of 4 different materials 1) steel, 2) sand (0,5-1 mm), 3) fine (2-4 mm) and 4) coarse (15-30 mm) rock-fragments and different roughness as well as moisture content are analysed. In addition, the signals are taken at 2 different angles to the soil's surface (90° and 70°). For quantification of the roughness, a photographic method (Structure-from-Motion) is applied to generate a detailed DEM and random roughness (RR) is calculated. To characterise the radar signal, different ratios of the reflected channels and polarisations are calculated. The signals show differences for all substrates, also clearly visible between sand and fine rock fragments, despite a wavelength of 1 cm of the

  19. Calculations of microwave brightness temperature of rough soil surfaces

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Wang, J. R.

    1985-01-01

    A model for simulating the brightness temperatures of soils with rough surfaces is developed. The surface emissivity of the soil media is obtained by the integration of the bistatic scattering coefficients for rough surfaces. The roughness of a soil surface is characterized by two parameters, the surface height standard deviation sigma and its horizontal correlation length l. The model calculations are compared to the measured angular variations of the polarized brightness temperatures at both 1.4 GHz and 5 GHz frequencies. A nonlinear least-squares fitting method is used to obtain the values of delta and l that best characterize the surface roughness. The effect of shadowing is incorporated by introducing a function S(theta), which represents the probability that a point on a rough surface is not shadowed by other parts of the surface. The model results for the horizontal polarization are in excellent agreement with the data. However, for the vertical polarization, some discrepancies exist between the calculations and data, particularly at the 1.4 GHz frequency. Possible causes of the discrepancy are discussed.

  20. Surface heating blanket for soil remediation

    SciTech Connect

    Van Egmond, C.F.; Carl, F.G. Jr.; Stegemeier, G.L.; Vinegar, H.J.

    1993-07-20

    A heater assembly is described for use in soil remediation comprising: a plurality of metallic support rods spaced parallel to each other; a continuous metallic strand spirally encircling adjacent ones of said support rods and forming rungs therearound, said rungs extending the length of said support rods, making low resistance contact therewith but being frictionally movable with respect thereto; an electric beater element located between and parallel to a selected pair of said support rods and between said rungs encircling said selected support rods, said heater being in low resistance frictional contact with said rungs along its length; a layer of insulation on top of said assembly; and an impermeable sheet placed on top of said insulation.

  1. Estimating rootzone soil moisture by assimilating both microwave based surface soil moisture and thermal based soil moisture proxy observations

    USDA-ARS?s Scientific Manuscript database

    A number of synthetic data assimilation experiments are carried out at the USDA Economic and Environmental Enhancement (OPE3) site in Beltsville, Maryland. As a first case, only surface soil moisture retrievals are assimilated into a land surface model using the Ensemble Kalman filter (EnKF). This...

  2. Soil fertility in deserts: a review on the influence of biological soil crusts and the effect of soil surface disturbance on nutrient inputs and losses

    USGS Publications Warehouse

    Reynolds, R.; Phillips, S.; Duniway, M.; Belnap, J.

    2003-01-01

    Sources of desert soil fertility include parent material weathering, aeolian deposition, and on-site C and N biotic fixation. While parent materials provide many soil nutrients, aeolian deposition can provide up to 75% of plant-essential nutrients including N, P, K, Mg, Na, Mn, Cu, and Fe. Soil surface biota are often sticky, and help retain wind-deposited nutrients, as well as providing much of the N inputs. Carbon inputs are from both plants and soil surface biota. Most desert soils are protected by cyanobacterial-lichen-moss soil crusts, chemical crusts and/or desert pavement. Experimental disturbances applied in US deserts show disruption of soil surfaces result in decreased N and C inputs from soil biota by up to 100%. The ability to glue aeolian deposits in place is compromised, and underlying soils are exposed to erosion. The ability to withstand wind increases with biological and physical soil crust development. While most undisturbed sites show little sediment production, disturbance by vehicles or livestock produce up to 36 times more sediment production, with soil movement initiated at wind velocities well below commonly-occurring wind speeds. Soil fines and flora are often concentrated in the top 3 mm of the soil surface. Winds across disturbed areas can quickly remove this material from the soil surface, thereby potentially removing much of current and future soil fertility. Thus, disturbances of desert soil surfaces can both reduce fertility inputs and accelerate fertility losses.

  3. Near surface soil vapor clusters for monitoring emissions of volatile organic compounds from soils.

    PubMed

    Ergas, S J; Hinlein, E S; Reyes, P O; Ostendorf, D W; Tehrany, J P

    2000-01-01

    The overall objective of this research was to develop and test a method of determining emission rates of volatile organic compounds (VOCs) and other gases from soil surfaces. Soil vapor clusters (SVCs) were designed as a low dead volume, robust sampling system to obtain vertically resolved profiles of soil gas contaminant concentrations in the near surface zone. The concentration profiles, when combined with a mathematical model of porous media mass transport, were used to calculate the contaminant flux from the soil surface. Initial experiments were conducted using a mesoscale soil remediation system under a range of experimental conditions. Helium was used as a tracer and trichloroethene was used as a model VOC. Flux estimations using the SVCs were within 25% of independent surface flux estimates and were comparable to measurements made using a surface isolation flux chamber (SIFC). In addition, method detection limits for the SVC were an order of magnitude lower than detection limits with the SIFC. Field trials, conducted with the SVCs at a bioventing site, indicated that the SVC method could be easily used in the field to estimate fugitive VOC emission rates. Major advantages of the SVC method were its low detection limits, lack of required auxiliary equipment, and ability to obtain real-time estimates of fugitive VOC emission rates.

  4. Comparing and Combining Surface Soil Moisture Products from AMSR2

    NASA Astrophysics Data System (ADS)

    Parinussa, R.; Kim, S.; Liu, Y.; Johnson, F.; Sharma, A.

    2015-12-01

    Soil moisture is an important variable in hydrological systems as its part of the water cycle in the atmosphere, the land surface and subsurface. Microwave remote sensing is a viable tool to monitor global soil moisture conditions at regular time intervals. The Advanced Microwave Scanning Radiometer 2 (AMSR2) is a sensor onboard the Global Change Observation Mission 1 - Water that was launched in May 2012. Multiple soil moisture products from AMSR2 observations exist; these were compared and combined with special emphasis to the global scale. The first product is retrieved by the Japan Aerospace Exploration Agency (JAXA) algorithm, the other uses the Land Parameter Retrieval Model (LPRM). These two products were compared against each other and evaluated against COSMOS data over the United States, Australia, Europe and Africa. The temporal correlations highlight differences in the representation of the seasonal cycle of soil moisture. It is hypothesized that four factors, physical surface temperatures, surface roughness, vegetation and ground soil wetness conditions, affect the quality of soil moisture retrievals. The complementary between the products led to the opportunity to combine them into a superior one that benefits from the strengths of both algorithms.These soil moisture algorithms share the same background in the radiative transfer model, but each algorithm applies different approaches to reflect various external conditions. As a result, the performance of the products is complementary in many locations in terms of bias, RMSE and, most importantly temporal correlation coefficients. Here, we present a methodology that combines the two AMSR2 based soil moisture products into a single product, which improves the overall performance by leveraging the strengths of the individual products. The new product is combined by applying an optimal weighting factor, calculated based on variance and correlation coefficients against a reference dataset. The complementary

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

    PubMed

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

    2016-02-01

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

  6. Predicting surface vibration from underground railways through inhomogeneous soil

    NASA Astrophysics Data System (ADS)

    Jones, Simon; Hunt, Hugh

    2012-04-01

    Noise and vibration from underground railways is a major source of disturbance to inhabitants near subways. To help designers meet noise and vibration limits, numerical models are used to understand vibration propagation from these underground railways. However, the models commonly assume the ground is homogeneous and neglect to include local variability in the soil properties. Such simplifying assumptions add a level of uncertainty to the predictions which is not well understood. The goal of the current paper is to quantify the effect of soil inhomogeneity on surface vibration. The thin-layer method (TLM) is suggested as an efficient and accurate means of simulating vibration from underground railways in arbitrarily layered half-spaces. Stochastic variability of the soil's elastic modulus is introduced using a K-L expansion; the modulus is assumed to have a log-normal distribution and a modified exponential covariance kernel. The effect of horizontal soil variability is investigated by comparing the stochastic results for soils varied only in the vertical direction to soils with 2D variability. Results suggest that local soil inhomogeneity can significantly affect surface velocity predictions; 90 percent confidence intervals showing 8 dB averages and peak values up to 12 dB are computed. This is a significant source of uncertainty and should be considered when using predictions from models assuming homogeneous soil properties. Furthermore, the effect of horizontal variability of the elastic modulus on the confidence interval appears to be negligible. This suggests that only vertical variation needs to be taken into account when modelling ground vibration from underground railways.

  7. Enhancement of chromate reduction in soils by surface modified biochar.

    PubMed

    Mandal, Sanchita; Sarkar, Binoy; Bolan, Nanthi; Ok, Yong Sik; Naidu, Ravi

    2017-01-15

    Chromium (Cr) is one of the common metals present in the soils and may have an extremely deleterious environmental impact depending on its redox state. Among two common forms, trivalent Cr(III) is less toxic than hexavalent Cr(VI) in soils. Carbon (C) based materials including biochar could be used to alleviate Cr toxicity through converting Cr(VI) to Cr(III). Incubation experiments were conducted to examine Cr(VI) reduction in different soils (Soil 1: pH 7.5 and Soil 2: pH 5.5) with three manures from poultry (PM), cow (CM) and sheep (SM), three respective manure-derived biochars (PM biochar (PM-BC), CM biochar (CM-BC) and SM biochar (SM-BC)) and two modified biochars (modified PM-BC (PM-BC-M) and modified SM-BC (SM-BC-M)). Modified biochar was synthesized by incorporating chitosan and zerovalent iron (ZVI) during pyrolysis. Among biochars, highest Cr(VI) reduction was observed with PM-BC application (5%; w/w) (up to 88.12 mg kg(-1); 45% reduction) in Soil 2 (pH 5.5). The modified biochars enhanced Cr(VI) reduction by 55% (SM-BC-M) compared to manure (29%, SM) and manure-derived biochars (40% reduction, SM-BC). Among the modified biochars, SM-BC-M showed a higher Cr(VI) reduction rate (55%) than PM-BC-M (48%) in Soil 2. Various oxygen-containing surface functional groups such as phenolic, carboxyl, carbonyl, etc. on biochar surface might act as a proton donor for Cr(VI) reduction and subsequent Cr(III) adsorption. This study underpins the immense potential of modified biochar in remediation of Cr(VI) contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Soil surface sealing reverse or promote desertification?

    NASA Astrophysics Data System (ADS)

    Assouline, Shmuel; Thompson, Sally; Chen, Li; Svoray, Tal; Sela, Shai; Katul, Gabriel

    2016-04-01

    Vegetation cover in dry regions is a key variable determining desertification. Bare soils exposed to rainfall by desertification can form physical crusts that reduce infiltration, exacerbating water stress on the remaining vegetation. Paradoxically, field studies show that crust removal is associated with plant mortality in desert systems, while artificial biological crusts can improve plant regeneration. Here, it is shown how physical crusts can act as either drivers of, or buffers against desertification depending on their environmental context. The behavior of crusts is first explored using a simplified theory for water movement on a uniform, partly vegetated slope subject to stationary hydrologic conditions. Numerical model runs supplemented with field data from a semiarid Long-Term Ecological Research (LTER) site are then applied to represent more realistic environmental conditions. When vegetation cover is significant, crusts can drive desertification, but this process is potentially self-limiting. For low vegetation cover, crusts mitigate against desertification by providing water subsidy to plant communities through a runoff-runon mechanism.

  9. Retrieval of Soil Moisture Using Extended Polarimetric Surface Scattering Models

    NASA Astrophysics Data System (ADS)

    Ponnurangam, G. G.; Rao, Y. S.

    2013-08-01

    In this paper, Bragg surface scattering model based three polarimetric surface scattering models have been investigated for soil moisture estimation and validation using Polarimetric SAR (PolSAR) data. The models are (a) X-Bragg model assumes uniform distribution for the width of orientation angle distribution. (b) Modified X- Bragg model assumes Gaussian distribution with 1.5 power correlation function. (c) Lee et al. proposed a new surface scattering model with a new distribution function. Moreover, some polarimetric parameters such as linear copolarization coherence (y), cross polarization power (|Shv|2) and orientation angle parameters in the coherency matrix elements (T12, T22 and T33) etc., have been analysed for various width of orientation angle distribution. Both 'H-α method' and 'Copol-Crosspol ratios method' are used for soil moisture inversion and the estimated mv (%) has been compared with semi-empirical polarimetric surface scattering models such as Oh et al. model and Dubois et al. model.

  10. Surface Roughness Parameter Uncertainties on Radar Based Soil Moisture Retrievals

    NASA Technical Reports Server (NTRS)

    Joseph, A. T.; vanderVelde, R.; O'Neill, P. E.; Lang, R.; Su, Z.; Gish, T.

    2012-01-01

    Surface roughness variations are often assumed to be negligible for the retrieval of sol moisture. Although previous investigations have suggested that this assumption is reasonable for natural vegetation covers (i.e. Moran et al. 2002), in-situ measurements over plowed agricultural fields (i.e. Callens et al. 2006) have shown that the soil surface roughness can change considerably due to weathering induced by rain.

  11. Aspects of Carbon and Sulfur Transformations in MOFEP Surface Soils

    Treesearch

    Henry G. Spratt

    1997-01-01

    Carbon and sulfur transformations were studied in surface soils from plots in MOFEP sites from August 1993 to May 1996 and in plots in watersheds ofMOFEP sites 1, 3, and 4 from May 1995 to May 1996. Element pools measured included total carbon, total sulfur, sulfate, and organic sulfur. Transformations quantified included lignocellulose mineralization and organic...

  12. Photodegradation of pesticides on plant and soil surfaces.

    PubMed

    Katagi, Toshiyuki

    2004-01-01

    importance of an emission spectrum of the light source near its surface was clarified. Most photochemical information comes from photolysis in organic solvents or on glass surfaces and/or plant metabolism studies. Epicuticular waxes may be approximated by long-chain hydrocarbons as a very viscous liquid or solid, but the existing form of pesticide molecules in waxes is still obscure. Either coexistence of formulation agents or steric constraint in the rigid medium would cause a change of molecular excitation, deactivation, and photodegradation mechanisms, which should be further investigated to understand the dissipation profiles of a pesticide in or on crops in the field. A thin-layer system with a coat of epicuticular waxes extracted from leaves or isolated cuticles has been utilized as a model, but its application has been very limited. There appear to be gaps in our knowledge about the surface chemistry and photochemistry of pesticides in both rigid media and plant metabolism. Photodegradation studies, for example, by using these models to eliminate contribution from metabolic conversion as much as possible, should be extensively conducted in conjunction with wax chemistry, with the controlling factors being clarified. As with soil surfaces, the effects of atmospheric oxidants should also be investigated. Based on this knowledge, new methods of kinetic analysis or a device simulating the fate of pesticides on these surfaces could be more rationally developed. Concerning soil photolysis, detailed mechanistic analysis of the mobility and fate of pesticides together with volatilization from soil surfaces has been initiated and its spatial distribution with time has been simulated with reasonable precision on a laboratory scale. Although mechanistic analyses have been conducted on penetration of pesticides through cuticular waxes, its combination with photodegradation to simulate the real environment is awaiting further investigation.

  13. The Effect of Soil Hydraulic Properties vs. Soil Texture in Land Surface Models

    NASA Technical Reports Server (NTRS)

    Gutmann, E. D.; Small, E. E.

    2005-01-01

    This study focuses on the effect of Soil Hydraulic Property (SHP) selection on modeled surface fluxes following a rain storm in a semi-arid environment. SHPs are often defined based on a Soil Texture Class (STC). To examine the effectiveness of this approach, the Noah land surface model was run with each of 1306 soils in a large SHP database. Within most STCs, the outputs have a range of 350 W/m2 for latent and sensible heat fluxes, and 8K for surface temperature. The average difference between STC median values is only 100 W/m2 for latent and sensible heat. It is concluded that STC explains 5-15% of the variance in model outputs and should not be used to determine SHPs.

  14. Passive microwave sensing of soil moisture content: Soil bulk density and surface roughness

    NASA Technical Reports Server (NTRS)

    Wang, J. R.

    1982-01-01

    Microwave radiometric measurements over bare fields of different surface roughnesses were made at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz to study the frequency dependence as well as the possible time variation of surface roughness. The presence of surface roughness was found to increase the brightness temperature of soils and reduce the slope of regression between brightness temperature and soil moisture content. The frequency dependence of the surface roughness effect was relatively weak when compared with that of the vegetation effect. Radiometric time series observation over a given field indicated that field surface roughness might gradually diminish with time, especially after a rainfall or irrigation. This time variation of surface roughness served to enhance the uncertainty in remote soil moisture estimate by microwave radiometry. Three years of radiometric measurements over a test site revealed a possible inconsistency in the soil bulk density determination, which turned out to be an important factor in the interpretation of radiometric data.

  15. Degradation and Sorption of Imidacloprid in Dissimilar Surface and Subsurface Soils

    USDA-ARS?s Scientific Manuscript database

    Degradation and sorption/desorption are important processes affecting the leaching of pesticides through soil. Once pesticides move past the surface soil layers, subsurface soil physical, chemical, and biological properties significantly affect pesticide fate and the potential for groundwater contam...

  16. Surface Wave Characterization of New Orleans Levee Soil Foundations

    NASA Astrophysics Data System (ADS)

    Delisser, T. A.; Lorenzo, J. M.; Hayashi, K.; Craig, M. S.

    2016-12-01

    Standard geotechnical tests such as the drilling of boreholes and cone penetration tests are able to assess soil stability at point locations vertically but lack lateral resolution in a complex sedimentary environment, such as the Louisiana Coastal system. Multi-Channel Analysis of Surface Waves (MASW) can complement geotechnical tests to improve certainty in resolving lateral features when predicting soil types in the near surface of levee soil foundations. A portion of the Inner-Harbor Navigation Canal levee wall that intersects the 9th Ward of New Orleans failed in the aftermath of Hurricane Katrina in 2005. Failures were attributed to floodwaters overtopping the levee wall and eroding its base. Geotechnical and geological data from test points can be used to calibrate continuous shear strength estimates derived from MASW. It is important to understand soil stability and strength to prevent future failures in New Orleans levee foundation soils. MASW analyzes the dispersive property of Rayleigh waves to develop shear wave velocity profiles for the near surface. Data are acquired using a seismic land streamer containing 4.5-Hz vertical-component geophones and a sledgehammer as the source. We plot and contour 18 inverted models of the interpreted fundamental mode and generate a 200-m-long profile to help us (1) better understand the characteristics of levee foundation soils as well as (2) improve existing geological cross-sections to help in future planning and maintenance of the levees. In comparison to the prior geological models, we find unexpected large vertical and horizontal shear-velocity gradients, as well as relatively low shear strengths throughout the seismic profile.

  17. Soil hydraulic parameters and surface soil moisture of a tilled bare soil plot inversely derived from l-band brightness temperatures

    USDA-ARS?s Scientific Manuscript database

    We coupled a radiative transfer approach with a soil hydrological model (HYDRUS 1D) and a global optimization routine SCE-UA to derive soil hydraulic parameters and soil surface roughness from measured brightness temperatures at 1.4 GHz (L-band) and measured rainfall and calculated potential soil ev...

  18. Physically plausible prescription of land surface model soil moisture

    NASA Astrophysics Data System (ADS)

    Hauser, Mathias; Orth, René; Thiery, Wim; Seneviratne, Sonia

    2016-04-01

    Land surface hydrology is an important control of surface weather and climate, especially under extreme dry or wet conditions where it can amplify heat waves or floods, respectively. Prescribing soil moisture in land surface models is a valuable technique to investigate this link between hydrology and climate. It has been used for example to assess the influence of soil moisture on temperature variability, mean and extremes (Seneviratne et al. 2006, 2013, Lorenz et al., 2015). However, perturbing the soil moisture content artificially can lead to a violation of the energy and water balances. Here we present a new method for prescribing soil moisture which ensures water and energy balance closure by using only water from runoff and a reservoir term. If water is available, the method prevents soil moisture decrease below climatological values. Results from simulations with the Community Land Model (CLM) indicate that our new method allows to avoid soil moisture deficits in many regions of the world. We show the influence of the irrigation-supported soil moisture content on mean and extreme temperatures and contrast our findings with that of earlier studies. Additionally, we will assess how long into the 21st century the new method will be able to maintain present-day climatological soil moisture levels for different regions. Lorenz, R., Argüeso, D., Donat, M.G., Pitman, A.J., den Hurk, B.V., Berg, A., Lawrence, D.M., Chéruy, F., Ducharne, A., Hagemann, S. and Meier, A., 2015. Influence of land-atmosphere feedbacks on temperature and precipitation extremes in the GLACE-CMIP5 ensemble. Journal of Geophysical Research: Atmospheres. Seneviratne, S.I., Lüthi, D., Litschi, M. and Schär, C., 2006. Land-atmosphere coupling and climate change in Europe. Nature, 443(7108), pp.205-209. Seneviratne, S.I., Wilhelm, M., Stanelle, T., Hurk, B., Hagemann, S., Berg, A., Cheruy, F., Higgins, M.E., Meier, A., Brovkin, V. and Claussen, M., 2013. Impact of soil moisture

  19. Soil surface roughness decay in contrasting climates, tillage types and management systems

    NASA Astrophysics Data System (ADS)

    Vidal Vázquez, Eva; Bertol, Ildegardis; Tondello Barbosa, Fabricio; Paz-Ferreiro, Jorge

    2014-05-01

    Soil surface roughness describes the variations in the elevation of the soil surface. Such variations define the soil surface microrelief, which is characterized by a high spatial variability. Soil surface roughness is a property affecting many processes such as depression storage, infiltration, sediment generation, storage and transport and runoff routing. Therefore the soil surface microrelief is a key element in hydrology and soil erosion processes at different spatial scales as for example at the plot, field or catchment scale. In agricultural land soil surface roughness is mainly created by tillage operations, which promote to different extent the formation of microdepressions and microelevations and increase infiltration and temporal retention of water. The decay of soil surface roughness has been demonstrated to be mainly driven by rain height and rain intensity, and to depend also on runoff, aggregate stability, soil reface porosity and soil surface density. Soil roughness formation and decay may be also influenced by antecedent soil moisture (either before tillage or rain), quantity and type of plant residues over the soil surface and soil composition. Characterization of the rate and intensity of soil surface roughness decay provides valuable information about the degradation of the upper most soil surface layer before soil erosion has been initiated or at the very beginning of soil runoff and erosion processes. We analyzed the rate of decay of soil surface roughness from several experiments conducted in two regions under temperate and subtropical climate and with contrasting land use systems. The data sets studied were obtained both under natural and simulated rainfall for various soil tillage and management types. Soil surface roughness decay was characterized bay several parameters, including classic and single parameters such as the random roughness or the tortuosity and parameters based on advanced geostatistical methods or on the fractal theory. Our

  20. Sensitivity of soil surface temperature in a force-restore equation to heat fluxes and deep soil temperature

    NASA Astrophysics Data System (ADS)

    Mihailovi, Dragutin T.; Kallos, George; Arseni, Ilija D.; Lali, Branislava; Rajkovi, Borivoj; Papadopoulos, Atanasios

    1999-11-01

    The force-restore approach is commonly used in order to calculate the surface temperature in atmospheric models. A critical point in this method is how to calculate the deep soil temperature which appears in the restore term of the force-restore equation. If the prognostic equation for calculating the deep soil temperature is used, some errors in surface temperature calculation and consequently in partitioning the surface energy and land surface water can be introduced. Usually, these errors should appear as a result of incorrect parameterization of surface energy terms in the prognostic equation based on force-restore approach.In this paper, the sensitivity of the force-restore model for surface temperature to the: (a) changes of soil heat flux; (b) variations of deep soil temperature and (c) changes in soil water evaporation is examined. In addition, the impact of the deep soil temperature variations on partitioning the surface energy and land surface water is discussed. Finally, a new procedure for calculating the deep soil temperature based, on climatological data of soil temperature and its exponential attenuation in the deep soil layers is suggested. All numerical experiments with the LAPS land surface scheme were performed using two data sets, obtained from the micrometeorological measurements over a bare soil at Rimski ančevi (Yugoslavia), RS, and Caumont (France), HAPEX.

  1. State of the art in telemedicine - concepts, management, monitoring and evaluation of the telemedicine programme in Alentejo (Portugal).

    PubMed

    Oliveira, Tiago Cravo; Branquinho, Maria José; Gonçalves, Luís

    2012-01-01

    Alentejo - one of five Portuguese continental regions - faces major problems impacting the health and social system of the region. Here, the low population density, the low educational and income level as well as an aging population have to be mentioned. Faced with the task of ensuring equal access to healthcare for all its inhabitants, the regional health authorities created the telemedicine program. From 1998 until 2000, the program developed in an experimental fashion, with teleconsultations involving a number of providers: primary health care centers, regional hospitals, and central hospitals. Between 2000 and 2010, there were a total of 135,000 telemedicine acts including teleconsultations, teleradiology (computerised tomography and x-rays), ultrasound telemedicine and telepathology. Presently, the network comprises 20 health centers and 6 hospitals, covering 4 districts. The platform is composed of high resolution videoconferencing equipment, software with patients' clinical records, an image archive, and a number of peripherals, such as electronic dermatoscopes and phonendoscopes. Teleconsultations are provided by fifteen medical specialties, across 3 district hospitals, ranging from neurology to pediatric surgery. In 2008, health authorities started the telelearning program, initially using point to point videoconferencing, and by the end of 2010, 848 healthcare professionals, across 52 locations, had participated in remote learning sessions, covering topics from chronic wound treatment, to infection control, to medical error. As of 2011, point to multipoint telelearning is also in operation. This paper provides an overview of the telemedicine program in Alentejo, including both infrastructure and operations. Preliminary results of an ongoing evaluation of the impact of teleconsultations on key indicators of the regional healthcare system are also presented (including current utilization and plans for future expansion). This article builds on the experience

  2. Carbon black retention in saturated natural soils: Effects of flow conditions, soil surface roughness and soil organic matter.

    PubMed

    Lohwacharin, J; Takizawa, S; Punyapalakul, P

    2015-10-01

    We evaluated factors affecting the transport, retention, and re-entrainment of carbon black nanoparticles (nCBs) in two saturated natural soils under different flow conditions and input concentrations using the two-site transport model and Kelvin probe force microscopy (KPFM). Soil organic matter (SOM) was found to create unfavorable conditions for the retention. Despite an increased flow velocity, the relative stability of the estimated maximum retention capacity in soils may suggest that flow-induced shear stress forces were insufficient to detach nCB. The KPFM observation revealed that nCBs were retained at the grain boundary and on surface roughness, which brought about substantial discrepancy between theoretically-derived attachment efficiency factors and the ones obtained by the experiments using the two-site transport model. Thus, decreasing ionic strength and increasing solution pH caused re-entrainment of only a small fraction of retained nCB in the soil columns.

  3. Direct measurement of surface carbon concentrations. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Filleux, C.; Tombrello, T. A.; Burnett, D. S.

    1977-01-01

    Measurements of surface concentrations of carbon in lunar soils and soil breccias provide information on the origin of carbon in the regolith. The reaction C-12 (d, p sub zero) is used to measure 'surface' and 'volume' concentrations in lunar samples. This method has a depth resolution of 1 micron, which permits only a 'surface' and a 'volume' component to be measured. Three of four Apollo 16 double drive tube samples show a surface carbon concentration of about 8 by 10 to the 14th power/sq cm, whereas the fourth sample gave 4 by 10 to the 14th power/sq cm. It can be convincingly shown that the measured concentration does not originate from fluorocarbon or hydrocarbon contaminants. Surface adsorbed layers of CO or CO2 are removed by a sputter cleaning procedure using a 2-MeV F beam. It is shown that the residual C concentration of 8 by 10 to the 14th power/sq cm cannot be further reduced by increased F fluence, and it is therefore concluded that it is truly lunar. If one assumes that the measured surface C concentration is a steady-state concentration determined only by a balance between solar-wind implantation and sputtering, a sputter erosion rate of 0.1 A/yr is obtained. However, it would be more profitable to use an independently derived sputter erosion rate to test the hypothesis of a solar-wind origin of the surface carbon.

  4. Direct measurement of surface carbon concentrations. [in lunar soil

    NASA Technical Reports Server (NTRS)

    Filleux, C.; Tombrello, T. A.; Burnett, D. S.

    1977-01-01

    Measurements of surface concentrations of carbon in lunar soils and soil breccias provide information on the origin of carbon in the regolith. The reaction C-12 (d, p sub zero) is used to measure 'surface' and 'volume' concentrations in lunar samples. This method has a depth resolution of 1 micron, which permits only a 'surface' and a 'volume' component to be measured. Three of four Apollo 16 double drive tube samples show a surface carbon concentration of about 8 by 10 to the 14th power/sq cm, whereas the fourth sample gave 4 by 10 to the 14th power/sq cm. It can be convincingly shown that the measured concentration does not originate from fluorocarbon or hydrocarbon contaminants. Surface adsorbed layers of CO or CO2 are removed by a sputter cleaning procedure using a 2-MeV F beam. It is shown that the residual C concentration of 8 by 10 to the 14th power/sq cm cannot be further reduced by increased F fluence, and it is therefore concluded that it is truly lunar. If one assumes that the measured surface C concentration is a steady-state concentration determined only by a balance between solar-wind implantation and sputtering, a sputter erosion rate of 0.1 A/yr is obtained. However, it would be more profitable to use an independently derived sputter erosion rate to test the hypothesis of a solar-wind origin of the surface carbon.

  5. Determination of antibiotic residues in manure, soil, and surface waters

    USGS Publications Warehouse

    Christian, T.; Schneider, R.J.; Farber, H.A.; Skutlarek, D.; Meyer, M.T.; Goldbach, H.E.

    2003-01-01

    In the last years more and more often detections of antimicrobially active compounds ("antibiotics") in surface waters have been reported. As a possible input pathway in most cases municipal sewage has been discussed. But as an input from the realm of agriculture is conceivable as well, in this study it should be investigated if an input can occur via the pathway application of liquid manure on fields with the subsequent mechanisms surface run-off/interflow, leaching, and drift. For this purpose a series of surface waters, soils, and liquid manures from North Rhine-Westphalia (Northwestern Germany) were sampled and analyzed for up to 29 compounds by HPLC-MS/MS. In each of the surface waters antibiotics could be detected. The highest concentrations were found in samples from spring (300 ng/L of erythromycin). Some of the substances detected (e.g., tylosin), as well as characteristics in the landscape suggest an input from agriculture in some particular cases. In the investigation of different liquid manure samples by a fast immunoassay method sulfadimidine could be detected in the range of 1...2 mg/kg. Soil that had been fertilized with this liquid manure showed a content of sulfadimidine extractable by accelerated solvent extraction (ASE) of 15 ??g/kg dry weight even 7 months after the application. This indicates the high stability of some antibiotics in manure and soil.

  6. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel: A preliminary report

    SciTech Connect

    Ligotke, M.W.

    1988-12-01

    Tests of wind erosion were performed in a controlled-environment wind tunnel to support the development of natural-material protective barriers for long-term isolation of radioactive waste. Barrier performance standards currently being developed for internal and external barrier performance are expected to mandate a surface layer that is resistant to wind erosion. The purpose of this study was to initiate a series of tests to determine suitable soil and gravel mixtures for such a barrier and to test worst-case surface layer conditions under the influence of high wind speeds. Six mixed soil and gravel surfaces were prepared, weathered to represent natural wind-blown desert areas, and subjected to controlled wind erosion forces in a wind tunnel. The applied erosive forces, including surface shear forces, were characterized to provide a means of relating wind tunnel results with actual field conditions. Soil particle losses from the surfaces caused by suspension, saltation, and surface creep were monitored by aerosol sample probes and mass balance measurements. 23 refs., 22 figs., 3 tabs.

  7. A new approach to predict soil temperature under vegetated surfaces.

    PubMed

    Dolschak, Klaus; Gartner, Karl; Berger, Torsten W

    2015-12-01

    In this article, the setup and the application of an empirical model, based on Newton's law of cooling, capable to predict daily mean soil temperature (Tsoil) under vegetated surfaces, is described. The only input variable, necessary to run the model, is a time series of daily mean air temperature. The simulator employs 9 empirical parameters, which were estimated by inverse modeling. The model, which primarily addresses forested sites, incorporates the effect of snow cover and soil freezing on soil temperature. The model was applied to several temperate forest sites, managing the split between Central Europe (Austria) and the United States (Harvard Forest, Massachusetts; Hubbard Brook, New Hampshire), aiming to cover a broad range of site characteristics. Investigated stands differ fundamentally in stand composition, elevation, exposition, annual mean temperature, precipitation regime, as well as in the duration of winter snow cover. At last, to explore the limits of the formulation, the simulator was applied to non-forest sites (Illinois), where soil temperature was recorded under short cut grass. The model was parameterized, specifically to site and measurement depth. After calibration of the model, an evaluation was performed, using ~50 % of the available data. In each case, the simulator was capable to deliver a feasible prediction of soil temperature in the validation time interval. To evaluate the practical suitability of the simulator, the minimum amount of soil temperature point measurements, necessary to yield expedient model performance was determined. In the investigated case 13-20 point observations, uniformly distributed within an 11-year timeframe, have been proven sufficient to yield sound model performance (root mean square error <0.9 °C, Nash-Sutcliffe efficiency >0.97). This makes the model suitable for the application on sites, where the information on soil temperature is discontinuous or scarce.

  8. Soil and water characteristics of a young surface mine wetland

    NASA Astrophysics Data System (ADS)

    Andrew Cole, C.; Lefebvre, Eugene A.

    1991-05-01

    Coal companies are reluctant to include wetland development in reclamation plans partly due to a lack of information on the resulting characteristics of such sites. It is easier for coal companies to recreate terrestrial habitats than to attempt experimental methods and possibly face significant regulatory disapproval. Therefore, we studied a young (10 years) wetland on a reclaimed surface coal mine in southern Illinois so as to ascertain soil and water characteristics such that the site might serve as a model for wetland development on surface mines. Water pH was not measured because of equipment problems, but evidence (plant life, fish, herpetofauna) suggests suitable pH levels. Other water parameters (conductivity, salinity, alkalinity, chloride, copper, total hardness, iron, manganese, nitrate, nitrite, phosphate, and sulfate) were measured, and only copper was seen in potentially high concentrations (but with no obvious toxic effects). Soil variables measured included pH, nitrate, nitrite, ammonia, potassium, calcium, magnesium, manganese, aluminum, iron, sulfate, chloride, and percent organic matter. Soils were slightly alkaline and most parameters fell within levels reported for other studies on both natural and manmade wetlands. Aluminum was high, but this might be indicative more of large amounts complexed with soils and therefore unavailable, than amounts actually accessible to plants. Organic matter was moderate, somewhat surprising given the age of the system.

  9. Shallow Subsurface Soil Moisture Dynamics in the Root-Zone and Bulk Soil of Sparsely Vegetated Land Surfaces as Impacted by Near-Surface Atmospheric State

    NASA Astrophysics Data System (ADS)

    Trautz, A.; Illangasekare, T. H.; Tilton, N.

    2015-12-01

    Soil moisture is a fundamental state variable that provides the water necessary for plant growth and evapotranspiration. Soil moisture has been extensively studied in the context of bare surface soils and root zones. Less attention has focused on the effects of sparse vegetation distributions, such as those typical of agricultural cropland and other natural surface environments, on soil moisture dynamics. The current study explores root zone, bulk soil, and near-surface atmosphere interactions in terms of soil moisture under different distributions of sparse vegetation using multi-scale laboratory experimentation and numerical simulation. This research is driven by the need to advance our fundamental understanding of soil moisture dynamics in the context of improving water conservation and next generation heat and mass transfer numerical models. Experimentation is performed in a two-dimensional 7.3 m long intermediate scale soil tank interfaced with a climate-controlled wind tunnel, both of which are outfitted with current sensor technologies for measuring atmospheric and soil variables. The soil tank is packed so that a sparsely vegetated soil is surrounded by bulk bare soil; the two regions are separated by porous membranes to isolate the root zone from the bulk soil. Results show that in the absence of vegetation, evaporation rates vary along the soil tank in response to longitudinal changes in humidity; soil dries fastest upstream where evaporation rates are highest. In the presence of vegetation, soil moisture in the bulk soil closest to a vegetated region decreases more rapidly than the bulk soil farther away. Evapotranspiration rates in this region are also higher than the bulk soil region. This study is the first step towards the development of more generalized models that account for non-uniformly distributed vegetation and land surfaces exhibiting micro-topology.

  10. Experimental study on soluble chemical transfer to surface runoff from soil.

    PubMed

    Tong, Juxiu; Yang, Jinzhong; Hu, Bill X; Sun, Huaiwei

    2016-10-01

    Prevention of chemical transfer from soil to surface runoff, under condition of irrigation and subsurface drainage, would improve surface water quality. In this paper, a series of laboratory experiments were conducted to assess the effects of various soil and hydraulic factors on chemical transfer from soil to surface runoff. The factors include maximum depth of ponding water on soil surface, initial volumetric water content of soil, depth of soil with low porosity, type or texture of soil and condition of drainage. In the experiments, two soils, sand and loam, mixed with different quantities of soluble KCl were filled in the sandboxes and prepared under different initial saturated conditions. Simulated rainfall induced surface runoff are operated in the soils, and various ponding water depths on soil surface are simulated. Flow rates and KCl concentration of surface runoff are measured during the experiments. The following conclusions are made from the study results: (1) KCl concentration in surface runoff water would decrease with the increase of the maximum depth of ponding water on soil surface; (2) KCl concentration in surface runoff water would increase with the increase of initial volumetric water content in the soil; (3) smaller depth of soil with less porosity or deeper depth of soil with larger porosity leads to less KCl transfer to surface runoff; (4) the soil with finer texture, such as loam, could keep more fertilizer in soil, which will result in more KCl concentration in surface runoff; and (5) good subsurface drainage condition will increase the infiltration and drainage rates during rainfall event and will decrease KCl concentration in surface runoff. Therefore, it is necessary to reuse drained fertile water effectively during rainfall, without polluting groundwater. These study results should be considered in agriculture management to reduce soluble chemical transfer from soil to surface runoff for reducing non-point sources pollution.

  11. Hanford Site surface soil radioactive contamination control plan, March 1993

    SciTech Connect

    Mix, P.D.; Winship, R.A.

    1993-04-01

    The Decommissioning and Resource Conservation and Recovery Act Closure Program is responsible to the US Department of Energy Richland Field Office, for the safe and cost-effective surveillance, maintenance, and decommissioning of surplus facilities and Resource Conservation and Recovery Act of 1976 closures at the Hanford Site. This program also manages the Radiation Area Remedial Action that includes the surveillance, maintenance, decontamination, and/or interim stabilization of inactive burial grounds, cribs, ponds, trenches, and unplanned release sites. This plan addresses only the Radiation Area Remedial Action activity requirements for managing and controlling the contaminated surface soil areas associated with these inactive sites until they are remediated as part of the Hanford Site environmental restoration process. All officially numbered Radiation Area Remedial Action and non-Radiation Area Remedial Action contaminated surface soil areas are listed in this document so that a complete list of the sites requiring remediation is contained in one document.

  12. Quantifying the Rate of Surface Soil Drying Following Precipitation Events Using PBO H2o Soil Moisture Time Series

    NASA Astrophysics Data System (ADS)

    Prue, A. M.

    2014-12-01

    Surface soil moisture affects latent and sensible heat fluxes, as well as setting the top boundary condition for water redistribution within the soil column. The fluctuations in surface soil moisture have been described in numerous modeling studies, but characterization based on measurements is lacking. We use a new soil moisture dataset based on reflected GPS signals to provide some constraints on rates of surface soil drying after a rain event. The soil moisture time series used in this study are derived from GPS data collected at NSF's EarthScope Plate Boundary Observatory (PBO) sites. The University of Colorado Boulder's PBO H2O project estimates daily near-surface soil moisture (approximately 0-5 cm) from the interference pattern between the direct and ground-reflected GPS signals. The sensing footprint is ~1000 m2, and thus intermediate in scale between in situ and remotely sensed observations. Twelve sites from this network of more than 100 were used in this study. To characterize the rate of soil drying, we fit exponential curves to daily soil moisture observations following ten isolated rainfall events at each site. Event sizes varied from 5 to 40 mm and were followed by 17 days without rain. The decay model fits the data quite well, with r2 values exceeding 0.85 in nearly all cases. For 95% of the events studied, the exponential decay constant (e-folding time) fell between 2 and 6 days. Precipitation amount is not correlated with drydown rates. Instead, the rate of soil drying is well-correlated with air temperature: the exponential constant decreases by 0.1 days per degree Celsius. We are currently investigating how other factors, such as soil type and vegetation, influence soil drying. This study highlights the utility of the PBO H2O soil moisture product. Surface soil moisture changes rapidly, and thus the dynamics of surface soil moisture cannot be accurately characterized using datasets based on less than daily measurements.

  13. Effects of near soil surface characteristics on soil detachment by overland flow in a natural succession grassland

    USDA-ARS?s Scientific Manuscript database

    Vegetation restoration probably has great effects on the process of soil detachment. This study was conducted to investigate the effects of near soil surface characteristics on soil detachment by overland flow in a 7-year naturally restored grassland. Four treatments were designed to characterize th...

  14. Methyl isothiocyanate and chloropicrin concentrations in bareroot forest nursery soils and above soil surface treatments following fumigation

    Treesearch

    Jennifer Juzwik

    2008-01-01

    Concentrations of methyl isothiocyanate (MITC) and chloropicrin (CP) in air spaces of nursery soil and in air at the soil surface following fumigation were determined in field trials in a Wisconsin and a Georgia nursery. MITC was measured in plots receiving either dazomet or co-application of metam sodium and chloropicrin; CP was measured in the latter plots. Soil...

  15. Surface Soil Moisture Estimates Across China Based on Multi-satellite Observations and A Soil Moisture Model

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Yang, Tao; Ye, Jinyin; Li, Zhijia; Yu, Zhongbo

    2017-04-01

    Soil moisture is a key variable that regulates exchanges of water and energy between land surface and atmosphere. Soil moisture retrievals based on microwave satellite remote sensing have made it possible to estimate global surface (up to about 10 cm in depth) soil moisture routinely. Although there are many satellites operating, including NASA's Soil Moisture Acitive Passive mission (SMAP), ESA's Soil Moisture and Ocean Salinity mission (SMOS), JAXA's Advanced Microwave Scanning Radiometer 2 mission (AMSR2), and China's Fengyun (FY) missions, key differences exist between different satellite-based soil moisture products. In this study, we applied a single-channel soil moisture retrieval model forced by multiple sources of satellite brightness temperature observations to estimate consistent daily surface soil moisture across China at a spatial resolution of 25 km. By utilizing observations from multiple satellites, we are able to estimate daily soil moisture across the whole domain of China. We further developed a daily soil moisture accounting model and applied it to downscale the 25-km satellite-based soil moisture to 5 km. By comparing our estimated soil moisture with observations from a dense observation network implemented in Anhui Province, China, our estimated soil moisture results show a reasonably good agreement with the observations (RMSE < 0.1 and r > 0.8).

  16. Effect of surface roughness on the microwave emission from soils

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Schmugge, T. J.; Newton, R. W.; Chang, A. T. C.

    1978-01-01

    The effect of surface roughness on the brightness temperature of a moist terrain was studied through the modification of Fresnel reflection coefficient and using the radiative transfer equation. The modification involves introduction of a single parameter to characterize the roughness. It is shown that this parameter depends on both the surface height variance and the horizontal scale of the roughness. Model calculations are in good quantitative agreement with the observed dependence of the brightness temperature on the moisture content in the surface layer. Data from truck mounted and airborne radiometers are presented for comparison. The results indicate that the roughness effects are greatest for wet soils where the difference between smooth and rough surfaces can be as great as 50K.

  17. On the Soil Roughness Parameterization Problem in Soil Moisture Retrieval of Bare Surfaces from Synthetic Aperture Radar

    PubMed Central

    Verhoest, Niko E.C; Lievens, Hans; Wagner, Wolfgang; Álvarez-Mozos, Jesús; Moran, M. Susan; Mattia, Francesco

    2008-01-01

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale. PMID:27879932

  18. On the Soil Roughness Parameterization Problem in Soil Moisture Retrieval of Bare Surfaces from Synthetic Aperture Radar.

    PubMed

    Verhoest, Niko E C; Lievens, Hans; Wagner, Wolfgang; Álvarez-Mozos, Jesús; Moran, M Susan; Mattia, Francesco

    2008-07-15

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unless accurate surface roughness parameter values are available, retrieving soil moisture from radar backscatter usually provides inaccurate estimates. The characterization of soil roughness is not fully understood, and a large range of roughness parameter values can be obtained for the same surface when different measurement methodologies are used. In this paper, a literature review is made that summarizes the problems encountered when parameterizing soil roughness as well as the reported impact of the errors made on the retrieved soil moisture. A number of suggestions were made for resolving issues in roughness parameterization and studying the impact of these roughness problems on the soil moisture retrieval accuracy and scale.

  19. Soil surface roughness characterization for microwave remote sensing applications

    NASA Astrophysics Data System (ADS)

    Marzahn, P.; Rieke-Zapp, D.; Ludwig, R.

    2012-04-01

    With this poster we present a simple and efficient method to measure soil surface roughness in an agricultural environment. Micro scale soil surface roughness is a crucial parameter in many environmental applications. In recent studies it is strongly recognized that soil surface roughness significantly influences the backscatter of agricultural surface, especially on bare fields. Indeed, while different roughness indices depend on their measurement length, no satisfying roughness parametrization and measurement technique has been found yet, introducing large uncertainty in the interpretation of the radar backscattering. In this study, we introduce a photogrammetric system which consists of a customized consumer grade Canon EOS 5d camera and a reference frame providing ground control points. With the system one can generate digital surface models (DSM) with a minimum size of 1 x 2.5 m2, extendable to any desired size, with a ground x,y- resolution of 2 mm. Using this approach, we generated a set of DSM with sizes ranging from 2.5 m2 to 22 m2, acquired over different roughness conditions representing ploughed, harrowed as well as crusted fields on different test sites. For roughness characterization we calculated in microwave remote sensing common roughness indices such as the RMS- height s and the autocorrelation length l. In an extensive statistical investigation we show the behavior of the roughness indices for different acquisition sizes of the proposed method. Results indicate, compared to results from profiles generated out of the dataset, that using a three dimensional measuring device, the calculated roughness indices are more robust in their estimation. In addition, a strong directional dependency of the proposed roughness indices was observed which could be related to the orientation of the seedbed rows to the acqusition direction. In a geostatistical analysis, we decomposed the acquired roughness indices into different scales, yielding a roughness quantity

  20. Soil and surface temperatures at the Viking landing sites

    NASA Technical Reports Server (NTRS)

    Kieffer, H. H.

    1976-01-01

    The annual temperature range for the Martian surface at the Viking lander sites is computed on the basis of thermal parameters derived from observations made with the infrared thermal mappers. The Viking lander 1 (VL1) site has small annual variations in temperature, whereas the Viking lander 2 (VL2) site has large annual changes. With the Viking lander images used to estimate the rock component of the thermal emission, the daily temperature behavior of the soil alone is computed over the range of depths accessible to the lander; when the VL1 and VL2 sites were sampled, the daily temperature ranges at the top of the soil were 183 to 263 K and 183 to 268 K, respectively. The diurnal variation decreases with depth with an exponential scale of about 5 centimeters. The maximum temperature of the soil sampled from beneath rocks at the VL2 site is calculated to be 230 K. These temperature calculations should provide a reference for study of the active chemistry reported for the Martian soil.

  1. Influence of surface and subsurface tillage on soil physical properties and soil/plant relationships of planted loblolly pine

    SciTech Connect

    D. L. Kelting; H. L. Allen

    2000-05-01

    Soil tillage can improve tree survival and growth by reducing competing vegetation, increasing nutrient availability, improving planting quality, and improving soil physical properties. The authors conducted a tillage study with competition control and nutrient amendments to isolate the physical effects of tillage on tree growth. The objectives of this study were to understand: (1) how tillage affects soil physical properties; (2) the relationships between these properties and root growth; (3) linkages between root growth response and aboveground growth; and (4) tillage effects on aboveground growth. Four replicates of a 2x2 factorial combination of surface (disking) and subsurface (subsoiling) were installed on a well-drained, clay-textured subsoil, soil located on the Piedmont of North Carolina. Disking improved soil physical properties (reduced bulk density and increased aeration porosity) in the surface 20-cm of soil. Subsoiling improved soil physical properties at all depths in the planting row, with improvements still noted at 60-cm from the planting row in the surface 10-cm of soil. Rooting patterns followed the changes in soil physical properties. Despite improvements in soil physical properties and changes in rooting patterns, aboveground tree growth was not affected by tillage. The results of this study point to the need for better diagnostics for identifying sites were tillage is appropriate in situations where fertilization and vegetation control are planned. Potential factors to consider are presence and abundance of old root channels, soil shrink/swell capacity, soil structure, presence and depth to root restricting layers, and historical precipitation records.

  2. Assimilation of neural network soil moisture in land surface models

    NASA Astrophysics Data System (ADS)

    Rodriguez-Fernandez, Nemesio; de Rosnay, Patricia; Albergel, Clement; Aires, Filipe; Prigent, Catherine; Kerr, Yann; Richaume, Philippe; Muñoz-Sabater, Joaquin; Drusch, Matthias

    2017-04-01

    In this study a set of land surface data assimilation (DA) experiments making use of satellite derived soil moisture (SM) are presented. These experiments have two objectives: (1) to test the information content of satellite remote sensing of soil moisture for numerical weather prediction (NWP) models, and (2) to test a simplified assimilation of these data through the use of a Neural Network (NN) retrieval. Advanced Scatterometer (ASCAT) and Soil Moisture and Ocean Salinity (SMOS) data were used. The SMOS soil moisture dataset was obtained specifically for this project training a NN using SMOS brightness temperatures as input and using as reference for the training European Centre for Medium-Range Weather Forecasts (ECMWF) H-TESSEL SM fields. In this way, the SMOS NN SM dataset has a similar climatology to that of the model and it does not present a global bias with respect to the model. The DA experiments are computed using a surface-only Land Data Assimilation System (so-LDAS) based on the HTESSEL land surface model. This system is very computationally efficient and allows to perform long surface assimilation experiments (one whole year, 2012). SMOS NN SM DA experiments are compared to ASCAT SM DA experiments. In both cases, experiments with and without 2 m air temperature and relative humidity DA are discussed using different observation errors for the ASCAT and SMOS datasets. Seasonal, geographical and soil-depth-related differences between the results of those experiments are presented and discussed. The different SM analysed fields are evaluated against a large number of in situ measurements of SM. On average, the SM analysis gives in general similar results to the model open loop with no assimilation even if significant differences can be seen for specific sites with in situ measurements. The sensitivity to observation errors to the SM dataset slightly differs depending on the networks of in situ measurements, however it is relatively low for the tests

  3. Rediscovering the palette of Alentejo (Southern Portugal) earth pigments: provenance establishment and characterization by LA-ICP-MS and spectra-colorimetric analysis

    NASA Astrophysics Data System (ADS)

    Gil, M.; Green, R.; Carvalho, M. L.; Seruya, A.; Queralt, I.; Candeias, A. E.; Mirão, J.

    2009-09-01

    Colored earth pigments sourced from Alentejo, Portugal, can be geologically categorized as either weathered carbonate rocks (terra rossas), schist units, or weathered iron ore deposits. The material was used until the mid-1900s by local residents as an ingredient in their traditional lime wash paintings and possibly in the production of artistic murals across the Alentejo region since pre-historic times. An integrated methodology incorporating laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and spectra-colorimetric analysis (CIELAB coordinates and reflectance curves), complemented by XRD, WDXRF, SEM-EDX, optical microscopy, and granulometric analysis, was used to characterize thirty-one Alentejo colored earths in an effort to correlate provenance with pigments properties. Data obtained from elemental analysis (major and trace) revealed a generic and similar elemental “fingerprint” that unable their distinction according to geographic provenance. Samples of weathered iron ore deposits derived from explored iron, copper, and sulfur mines are more easily discriminated using the chalcophilic (“sulfur-loving“) elements. Color analysis revealed a range of hues; olive-yellow to dark reddish-brown owing mainly to differences in the type and proportion of the color component present, independent of the accessory mineral.

  4. Spatial and temporal distribution of cyanobacterial soil crusts in the Kalahari: Implications for soil surface properties

    NASA Astrophysics Data System (ADS)

    Thomas, A. D.; Dougill, A. J.

    2007-03-01

    Localised patterns of erosion and deposition in vegetated semi-arid rangelands have been shown to influence ecological change and biogeochemical cycles. In the flat, vegetated Kalahari rangelands of Southern Africa the factors regulating erodibility of the fine sand soils and the erosivity of wind regimes require further investigation. This paper reports on the spatial and temporal patterns of cyanobacterial soil crust cover from ten sites at five sampling locations in the semi-arid Kalahari and discusses the likely impact on factors regulating surface erodibility and erosivity. Cyanobacterial soil crust cover on Kalahari Sand varied between 11% and 95% of the ground surface and was higher than previously reported. Cover was inversely related to grazing with the lowest crust cover found close to boreholes and the highest in the Game Reserve and Wildlife Management Zone. In grazed areas, crusts form under the protective canopies of the thorny shrub Acacia mellifera. Fenced plot data showed that crusts recover quickly from disturbance, with a near complete surface crust cover forming within 15 months of disturbance. Crust development is restricted by burial by wind blown sediment and by raindrop impact. Crusts had significantly greater organic matter and total nitrogen compared to unconsolidated surfaces. Crusts also significantly increased the compressive strength of the surface (and thus decreased erodibility) and changed the surface roughness. Establishing exactly how these changes affect aeolian erosion requires further process-based studies. The proportion of shear velocity acting on the surface in this complex mixed bush-grass-crust environment will be the key to understanding how crusts affect erodibility.

  5. [Effects of soil surface mulching on solar greenhouse grafted and own-rooted cucumber growth and soil environment].

    PubMed

    Zhai, Sheng; Liang, Yinli; Wang, Juyuan

    2005-12-01

    The study on the effects of different soil surface mulching models, including wheat straw mulching (WS), plastic film mulching (PF), and wheat straw plus plastic film mulching (WP), on the growth of solar greenhouse grafted and own-rooted cucumber and on soil environment showed that soil surface mulching not only increased the individuals of pistillate flower, improved its differentiation and development, shortened fruit-developing period, increased fruit weight, reduced fruit malformation percentage, but also raised total yield. Among the test mulching models, WP was better than WS and PF, and the effects were superior on grafted than on own-rooted cucumber. Soil surface mulching also had considerable effects on soil environment, but the effects varied with different modules. For example, under field condition, the diurnal change of soil temperature was a single-peak curve, with its peak higher and appeared at 14:30 in 5 cm and 10 cm soil depth, but lower and appeared later in deeper soil layers. In this study, WS lowered the maximum soil temperature and raised the minimum soil temperature, making soil temperature quite stable, while PF raised the maximum soil temperature much higher and enhanced the minimum soil temperature less than WS and WP, making the largest variation range of soil temperature. WP played a role of raising soil temperature and kept it stable. Similar to the diurnal change of soil temperature at 5 cm and 10 cm depth, that of soil respiration rate was also a single-peak curve. The soil respiration rate in all treatmentg was significantly higher than that of CK, and WP had a higher soil respiration rate than PF and WS. There was a significant positive correlation between soil respiration rate and soil temperature at 5 cm and 10 cm depth. By the end of the experiment, soil bulk density at the depth of 0-20 cm was measured, which was significantly lower in WS and WP than in CK and PF. The difference in soil bulk density was gradually inconspicuous

  6. Residues of organochlorine pesticides in surface soil and raw ...

    EPA Pesticide Factsheets

    The central Asian Republic of Tajikistan has been an area of extensive historical agricultural pesticide use as well as large scale burials of obsolete banned chlorinated insecticides. The current investigation was a four year study of legacy organochlorine pesticides in surface soil and raw foods in four rural areas of Tajikistan. The four study areas included the pesticide burial sites of Konibodom and Vakhsh, and family farms of Garm and Chimbuloq villages. These areas were selected to represent a diversity of pesticide disposal histories and to allow assessment of local pesticide contamination in Tajikistan. Each site was visited multiple times and over 500 samples of surface soil and raw foods were collected and analyzed for twenty legacy organochlorine pesticides. Various local food products were sampled to represent the range of raw foods potentially containing residues of banned pesticides, including dairy products, meat, edible plant and cotton seed products. The pesticide analytes included DDTs (DDT, DDD, DDE), lindane isomers (α, β, γ, δ BHC), endosulfan isomers (endosulfan I, II, sulfate), other cyclodienes (aldrin, α and γ chlordanes, dieldrin, endrin, endrin aldehyde and ketone, heptachlor, heptachlor epoxide), and methoxychlor. Pesticide analytes were selected based on availability of commercial standards and known or suspected historical pesticide use and burial. Pesticide contamination was highest in soil at each of the four sites, and ge

  7. Evaluating near-surface soil moisture using Heat Capacity Mapping Mission data

    NASA Technical Reports Server (NTRS)

    Heilman, J. L.; Moore, D. G.

    1982-01-01

    Four dates of Heat Capacity Mapping Mission (HCMM) data were analyzed in order to evaluate HCMM thermal data use in estimating near-surface soil moisture in a complex agricultural landscape. Because of large spatial and temporal ground cover variations, HCMM radiometric temperatures alone did not correlate with soil water content. The radiometric temperatures consisted of radiance contributions from different canopies and their respective soil backgrounds. However, when surface soil temperatures were empirically estimated from HCMM temperatures and percent cover of each pixel, a highly significant correlation was obtained between the estimated soil temperatures and near-surface soil water content.

  8. The impact of land surface temperature on soil moisture anomaly detection from passive microwave observations

    USDA-ARS?s Scientific Manuscript database

    For several years passive microwave observations have been used to retrieve soil moisture from the Earth’s surface. Low frequency observations have the most sensitivity to soil moisture, therefore the modern Soil Moisture and Ocean Salinity (SMOS) and future Soil Moisture Active and Passive (SMAP) ...

  9. Soil texture and granulometry at the surface of Mars

    NASA Astrophysics Data System (ADS)

    Dollfus, A.; Deschamps, M.; Zimbelman, J. R.

    1993-02-01

    Attention is given to a characterization of the physical behavior of the Martian upper surface in its first few decimeters on the basis of mutual relationships between three parameters: the linear polarization of the reflected light, the visual albedo, and the thermal inertia. Polarimetric scans raked a strip covering two contrasting regions, the dark-hued Mare Erythraeum, and the light-hued Thaumasia. Erythraeum is characterized everywhere by a uniform polarization response, despite the large geomorphological diversity of the surface. A ubiquitous coating or mantling with small dark grains of albedo 12.7 percent, with a radius of 10 to 20 microns, is indicated. Thaumasia exhibits a large variety of soil properties. A typical location with albedo of 16.3 percent has a surface covered with orange grains, probably very dispersed in size, for which the largest grains are 20 to 40 microns.

  10. Variation of soil surface roughness under simulated rainfall

    NASA Astrophysics Data System (ADS)

    Tarquis, A. M.; Saa-Requejo, A.; Valencia, J. L.; Moratiel, R.; Paz-Gonzalez, A.

    2012-04-01

    Soil surface micro-topography or roughness (SSR) defines the physical boundary between overland flow and soil. Due to its unique position, soil roughness potentially affects surface processes such as infiltration, flow routing, erosion and sedimentation. Thus the decay of SSR under different rainfall intensities is of most interest in soil erosion. While some authors have chosen exponent function of cumulative rainfall to describe the decay of SSR, others have used the kinetic energy of rainfall. SSR at the field level is an easy visually perceptible notion, but difficult to describe numerically. In this study we didn't use pin-meter or laser techniques to quantify SSR. Percentage of micro-topographic shadows, under fixed sunlight conditions, has been applied based on former works that proved it is an easy and reliable method to estimate SSR. Two experimental plots, of 1m x 1m, were subjected to successive simulated rainfall events with an intensity of 67 mm/h and a height of 2 m. Both plots were a harrowed plot with an oriented roughness and 6% slope. Images were obtained each 15 minutes of rainfall with an incident angle of light of 45° approximately. The image was acquired by an OLYMPUS X-925, having a size of 2976x3968 pixels and corresponding to an area of 75 cm x 100 cm. For denoising process, the image was cropped to 590x800 pixels and for image binarization Indicator Kriging (IK) method was used. Comparisons of both plots respect to SSR evolution, runoff accumulation and shadows morphology are showed. Acknowledgements Funding provided by Spanish Ministerio de Ciencia e Innovación (MICINN) through project no. AGL2010-21501/AGR is greatly appreciated.

  11. Soil erosion rates from mixed soil and gravel surfaces in a wind tunnel

    SciTech Connect

    Ligotke, M.W.; Klopfer, D.C.

    1990-08-01

    Protective barriers have been identified as integral components of plans to isolate defense waste on the Hanford Site. The use of natural materials to construct protective barriers over waste site is being considered. Design requirements for protective barriers include preventing exposure of buried waste, and restricting penetration or percolation of surface waters through the waste zone. Studies were initiated to evaluate the effects of wind erosion on candidate protective barrier surfaces. A wind tunnel was used to provide controlled erosive stresses and to investigate the erosive effects of wind forces on proposed surface layers for protective barriers. Mixed soil and gravel surfaces were prepared and tested for resistance to wind erosion at the Pacific Northwest Laboratory Aerosol Wind Tunnel Research Facility. These tests were performed to investigate surface deflation caused by suspension of soil from various surface layer configurations and to provide a comparison of the relative resistance of the different surfaces to wind erosion. Planning, testing, and analyzing phases of this wind erosion project were coordinated with other tasks supporting the development of protective barriers. These tasks include climate-change predictions, field studies and modeling efforts. This report provides results of measurements of deflation caused by wind forces over level surfaces. Section 2.0 reviews surface layer characteristics and previous relevant studies on wind erosion, describes effects of erosion, and discusses wind tunnel modeling. Materials and methods of the wind tunnel tests are discussed in Section 3.0. Results and discussion are presented in Section 4.0, and conclusions and recommendations Section 5.0. 53 refs., 29 figs., 7 tabs.

  12. Using infrared thermography for understanding and quantifying soil surface processes

    NASA Astrophysics Data System (ADS)

    de Lima, João L. M. P.

    2017-04-01

    At present, our understanding of the soil hydrologic response is restricted by measurement limitations. In the literature, there have been repeatedly calls for interdisciplinary approaches to expand our knowledge in this field and eventually overcome the limitations that are inherent to conventional measuring techniques used, for example, for tracing water at the basin, hillslope and even field or plot scales. Infrared thermography is a versatile, accurate and fast technique of monitoring surface temperature and has been used in a variety of fields, such as military surveillance, medical diagnosis, industrial processes optimisation, building inspections and agriculture. However, many applications are still to be fully explored. In surface hydrology, it has been successfully employed as a high spatial and temporal resolution non-invasive and non-destructive imaging tool to e.g. access groundwater discharges into waterbodies or quantify thermal heterogeneities of streams. It is believed that thermal infrared imagery can grasp the spatial and temporal variability of many processes at the soil surface. Thermography interprets the heat signals and can provide an attractive view for identifying both areas where water is flowing or has infiltrated more, or accumulated temporarily in depressions or macropores. Therefore, we hope to demonstrate the potential for thermal infrared imagery to indirectly make a quantitative estimation of several hydrologic processes. Applications include: e.g. mapping infiltration, microrelief and macropores; estimating flow velocities; defining sampling strategies; identifying water sources, accumulation of waters or even connectivity. Protocols for the assessment of several hydrologic processes with the help of IR thermography will be briefly explained, presenting some examples from laboratory soil flumes and field.

  13. Light structures phototroph, bacterial and fungal communities at the soil surface.

    PubMed

    Davies, Lawrence O; Schäfer, Hendrik; Marshall, Samantha; Bramke, Irene; Oliver, Robin G; Bending, Gary D

    2013-01-01

    The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0-3 mm) and bulk soil (3-12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere.

  14. Light Structures Phototroph, Bacterial and Fungal Communities at the Soil Surface

    PubMed Central

    Davies, Lawrence O.; Schäfer, Hendrik; Marshall, Samantha; Bramke, Irene; Oliver, Robin G.; Bending, Gary D.

    2013-01-01

    The upper few millimeters of soil harbour photosynthetic microbial communities that are structurally distinct from those of underlying bulk soil due to the presence of light. Previous studies in arid zones have demonstrated functional importance of these communities in reducing soil erosion, and enhancing carbon and nitrogen fixation. Despite being widely distributed, comparative understanding of the biodiversity of the soil surface and underlying soil is lacking, particularly in temperate zones. We investigated the establishment of soil surface communities on pasture soil in microcosms exposed to light or dark conditions, focusing on changes in phototroph, bacterial and fungal communities at the soil surface (0–3 mm) and bulk soil (3–12 mm) using ribosomal marker gene analyses. Microbial community structure changed with time and structurally similar phototrophic communities were found at the soil surface and in bulk soil in the light exposed microcosms suggesting that light can influence phototroph community structure even in the underlying bulk soil. 454 pyrosequencing showed a significant selection for diazotrophic cyanobacteria such as Nostoc punctiforme and Anabaena spp., in addition to the green alga Scenedesmus obliquus. The soil surface also harboured distinct heterotrophic bacterial and fungal communities in the presence of light, in particular, the selection for the phylum Firmicutes. However, these light driven changes in bacterial community structure did not extend to the underlying soil suggesting a discrete zone of influence, analogous to the rhizosphere. PMID:23894406

  15. Microbial transformation of nitroaromatics in surface soils and aquifer materials

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.; Schumacher, J.G.

    1994-01-01

    Microorganisms indigenous to surface soils and aquifer materials collected at a munitions-contaminated site transformed 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to amino-nitro intermediates within 20 to 70 days. Carbon mineralization studies with both unlabeled (TNT, 2,4-DNT, and 2,6-DNT) and radiolabeled ([14C]TNT) substrates indicated that a significant fraction of these source compounds was degraded to CO2.

  16. Soil surface roughness: comparing old and new measuring methods and application in a soil erosion model

    NASA Astrophysics Data System (ADS)

    Thomsen, L. M.; Baartman, J. E. M.; Barneveld, R. J.; Starkloff, T.; Stolte, J.

    2015-04-01

    Quantification of soil roughness, i.e. the irregularities of the soil surface due to soil texture, aggregates, rock fragments and land management, is important as it affects surface storage, infiltration, overland flow, and ultimately sediment detachment and erosion. Roughness has been measured in the field using both contact methods (such as roller chain and pinboard) and sensor methods (such as stereophotogrammetry and terrestrial laser scanning (TLS)). A novel depth-sensing technique, originating in the gaming industry, has recently become available for earth sciences: the Xtion Pro method. Roughness data obtained using various methods are assumed to be similar; this assumption is tested in this study by comparing five different methods to measure roughness in the field on 1 m2 agricultural plots with different management (ploughing, harrowing, forest and direct seeding on stubble) in southern Norway. Subsequently, the values were used as input for the LISEM soil erosion model to test their effect on the simulated hydrograph at catchment scale. Results show that statistically significant differences between the methods were obtained only for the fields with direct seeding on stubble; for the other land management types the methods were in agreement. The spatial resolution of the contact methods was much lower than for the sensor methods (10 000 versus at least 57 000 points per square metre). In terms of costs and ease of use in the field, the Xtion Pro method is promising. Results from the LISEM model indicate that especially the roller chain overestimated the random roughness (RR) values and the model subsequently calculated less surface runoff than measured. In conclusion, the choice of measurement method for roughness data matters and depends on the required accuracy, resolution, mobility in the field and available budget. It is recommended to use only one method within one study.

  17. Soil surface roughness: comparing old and new measuring methods and application in a soil erosion model

    NASA Astrophysics Data System (ADS)

    Thomsen, L. M.; Baartman, J. E. M.; Barneveld, R. J.; Starkloff, T.; Stolte, J.

    2014-11-01

    Quantification of soil roughness, i.e. the irregularities of the soil surface due to soil texture, aggregates, rock fragments and land management, is important as it affects surface storage, infiltration, overland flow and ultimately sediment detachment and erosion. Roughness has been measured in the field using both contact methods, such as roller chain and pinboard, and sensor methods, such as stereophotogrammetry and terrestrial laser scanning (TLS). A novel depth sensing technique, originating in the gaming industry, has recently become available for earth sciences; the Xtion Pro method. Roughness data obtained using various methods are assumed to be similar; this assumption is tested in this study by comparing five different methods to measure roughness in the field on 1 m2 agricultural plots with different management (ploughing, harrowing, forest and direct seeding on stubble) in southern Norway. Subsequently, the values were used as input for the LISEM soil erosion model to test their effect on the simulated hydrograph on catchment scale. Results show that statistically significant differences between the methods were obtained only for the fields with direct drilling on stubble; for the other land management types the methods were in agreement. The spatial resolution of the contact methods was much lower than for the sensor methods (10 000 versus at least 57 000 points per m2 respectively). In terms of costs and ease of handling in the field, the Xtion Pro method is promising. Results from the LISEM model indicate that especially the roller chain underestimated the RR values and the model thereby calculated less surface runoff than measured. In conclusion: the choice of measurement method for roughness data matters and depends on the required accuracy, resolution, mobility in the field and available budget. It is recommended to use only one method within one study.

  18. Application of a mesoscale atmospheric coupled fire model BRAMS-SFIRE to Alentejo wildland fire and comparison of performance with the fire model WRF-SFIRE

    NASA Astrophysics Data System (ADS)

    Menezes, Isilda; Freitas, Saulo; Stockler, Rafael; Mello, Rafael; Ribeiro, Nuno; Corte-Real, João; Surový, Peter

    2015-04-01

    Models of fuel with the identification of vegetation patterns of Montado ecosystem in Portugal was incorporated in the mesoscale Brazilian Atmospheric Modeling System (BRAMS) and coupled with a spread wildland fire model. The BRAMS-FIRE is a new system developed by the Centro de Previsão de Tempo e Estudos Climáticos (CPTEC/INPE, Brazil) and the Instituto de Ciências Agrárias e Ambientais Mediterrâneas (ICAAM, Portugal). The fire model used in this effort was originally, developed by Mandel et al. (2013) and further incorporated in the Weather Research and Forecast model (WRF). Two grids of high spatial resolution were configured with surface input data and fuel models integrated for simulations using both models BRAMS-SFIRE and WRF-SFIRE. One grid was placed in the plain land and the other one in the hills to evaluate different types of fire propagation and calibrate BRAMS-SFIRE. The objective is simulating the effects of atmospheric circulation in local scale, namely the movements of the heat front and energy release associated to it, obtained by this two models in an episode of wildland fire which took place in Alentejo area in the last decade, for application to planning and evaluations of agro wildland fire risks. We aim to model the behavior of forest fires through a set of equations whose solutions provide quantitative values of one or more variables related to the propagation of fire, described by semi-empirical expressions that are complemented by experimental data allow to obtain the main variables related advancing the perimeter of the fire, as the propagation speed, the intensity of the fire front and fuel consumption and its interaction with atmospheric dynamic system References Mandel, J., J. D. Beezley, G. Kelman, A. K. Kochanski, V. Y. Kondratenko, B. H. Lynn, and M. Vejmelka, 2013. New features in WRF-SFIRE and the wildfire forecasting and danger system in Israel. Natural Hazards and Earth System Sciences, submitted, Numerical Wildfires, Carg

  19. Application of a Mesoscale Atmospheric Coupled Fire Model BRAMS-FIRE to Alentejo Woodland Fire and Comparison of Performance with the Fire Model WRF-Sfire.

    NASA Astrophysics Data System (ADS)

    Freitas, S. R.; Menezes, I. C.; Stockler, R.; Mello, R.; Ribeiro, N. A.; Corte-Real, J. A. M.; Surový, P.

    2014-12-01

    Models of fuel with the identification of vegetation patterns of Montado ecosystem in Portugal was incorporated in the mesoscale Brazilian Atmospheric Modeling System (BRAMS) and coupled with a spread woodland fire model. The BRAMS-FIRE is a new system developed by the "Centro de Previsão de Tempo e Estudos Climáticos" (CPTEC/INPE, Brazil) and the "Instituto de Ciências Agrárias e Ambientais Mediterrâneas" (ICAAM, Portugal). The fire model used in this effort was originally, developed by Mandel et al. (2013) and further incorporated in the Weather Research and Forecast model (WRF). Two grids of high spatial resolution were configured with surface input data and fuel models integrated for simulations using both models BRAMS-FIRE and WRF-SFIRE. One grid was placed in the plain land near Beja and the other one in the hills of Ossa to evaluate different types of fire propagation and calibrate BRAMS-FIRE. The objective is simulating the effects of atmospheric circulation in local scale, namely the movements of the heat front and energy release associated to it, obtained by this two models in an episode of woodland fire which took place in Alentejo area in the last decade, for application to planning and evaluations of agro woodland fire risks. We aim to model the behavior of forest fires through a set of equations whose solutions provide quantitative values of one or more variables related to the propagation of fire, described by semi-empirical expressions that are complemented by experimental data allow to obtain the main variables related advancing the perimeter of the fire, as the propagation speed, the intensity of the fire front and fuel consumption and its interaction with atmospheric dynamic system. References Mandel, J., J. D. Beezley, G. Kelman, A. K. Kochanski, V. Y. Kondratenko, B. H. Lynn, and M. Vejmelka, 2013. New features in WRF-SFIRE and the wildfire forecasting and danger system in Israel. Natural Hazards and Earth System Sciences, submitted

  20. Evaluating soil moisture constraints on surface fluxes in land surface models globally

    NASA Astrophysics Data System (ADS)

    Harris, Phil; Gallego-Elvira, Belen; Taylor, Christopher; Folwell, Sonja; Ghent, Darren; Veal, Karen; Hagemann, Stefan

    2016-04-01

    Soil moisture availability exerts a strong control over land evaporation in many regions. However, global climate models (GCMs) disagree on when and where evaporation is limited by soil moisture. Evaluation of the relevant modelled processes has suffered from a lack of reliable, global observations of land evaporation at the GCM grid box scale. Satellite observations of land surface temperature (LST) offer spatially extensive but indirect information about the surface energy partition and, under certain conditions, about soil moisture availability on evaporation. Specifically, as soil moisture decreases during rain-free dry spells, evaporation may become limited leading to increases in LST and sensible heat flux. We use MODIS Terra and Aqua observations of LST at 1 km from 2000 to 2012 to assess changes in the surface energy partition during dry spells lasting 10 days or longer. The clear-sky LST data are aggregated to a global 0.5° grid before being composited as a function dry spell day across many events in a particular region and season. These composites are then used to calculate a Relative Warming Rate (RWR) between the land surface and near-surface air. This RWR can diagnose the typical strength of short term changes in surface heat fluxes and, by extension, changes in soil moisture limitation on evaporation. Offline land surface model (LSM) simulations offer a relatively inexpensive way to evaluate the surface processes of GCMs. They have the benefits that multiple models, and versions of models, can be compared on a common grid and using unbiased forcing. Here, we use the RWR diagnostic to assess global, offline simulations of several LSMs (e.g., JULES and JSBACH) driven by the WATCH Forcing Data-ERA Interim. Both the observed RWR and the LSMs use the same 0.5° grid, which allows the observed clear-sky sampling inherent in the underlying MODIS LST to be applied to the model outputs directly. This approach avoids some of the difficulties in analysing free

  1. Effect of some surface and subsurface attributes on soil water erosion

    NASA Astrophysics Data System (ADS)

    Bertol, Ildegardis; César Ramos, Júlio; Vidal Vázquez, Eva; Mirás Avalos, José Manuel

    2013-04-01

    Soil erosion is a complex phenomenon depending on climate, topography, soil intrinsic characteristics, crop and residue cover, and management and conservation practices that may be accelerated by man activities. Within the above mentioned factors, soil cover and soil management most influence soil erosion. Soil management includes mechanical mobilization and in soil conservationist systems soil residues are mobilized for increasing soil surface roughness. Even if soil roughness is ephemeral, it increases soil water storage and sediment retention in surface microdepressions, which contributes to decrease water erosion. Conservationist soil management systems also maintain the soil surface covered by crop residues, which are more persistent than roughness and contribute to dissipate kinetic energy from raindrops and partly also from runoff. Crop residues are more efficient than soil roughness in controlling water erosion because of its ability to retain detached soil particles. The objective of this study was to assess the efficiency of both soil cover by crop residues and soil surface roughness in controlling water erosion. A field experiments was performed on an Inceptisol in South Brazil under simulated rainfall conditions during 2012. The following treatments were evaluated: 1) residues of Italian ryegrass (Lolium multiflorum), 2) residues of common vetch (Vicia sativa), 3) scarification after cultivation of Italian ryegrass, 4) scarification after cultivation of common vetch, 5) scarified bare soil with high roughness as a control. Treatments #1 and 2 involved no-tilled soil with a rather smooth soil surface, where roots and crop residues of the previous crop were maintained. Treatments # 3 and 4 involved a rather high roughness, absence of previous crop residues and maintenance of antecedent roots. Experimental plots were 11 m long and 3.5 m wide with an area of 38.5 m2. Six successive simulated rainfall tests were applied using a rotating-boom rain simulator

  2. Impact of sea-level rise on earthquake and landslide triggering offshore the Alentejo margin (SW Iberia)

    NASA Astrophysics Data System (ADS)

    Neves, M. C.; Roque, C.; Luttrell, K. M.; Vázquez, J. T.; Alonso, B.

    2016-12-01

    Earthquakes and submarine landslides are recurrent and widespread manifestations of fault activity offshore SW Iberia. The present work tests the effects of sea-level rise on offshore fault systems using Coulomb stress change calculations across the Alentejo margin. Large-scale faults capable of generating large earthquakes and tsunamis in the region, especially NE-SW trending thrusts and WNW-ESE trending dextral strike-slip faults imaged at basement depths, are either blocked or unaffected by flexural effects related to sea-level changes. Large-magnitude earthquakes occurring along these structures may, therefore, be less frequent during periods of sea-level rise. In contrast, sea-level rise promotes shallow fault ruptures within the sedimentary sequence along the continental slope and upper rise within distances of <100 km from the coast. The results suggest that the occurrence of continental slope failures may either increase (if triggered by shallow fault ruptures) or decrease (if triggered by deep fault ruptures) as a result of sea-level rise. Moreover, observations of slope failures affecting the area of the Sines contourite drift highlight the role of sediment properties as preconditioning factors in this region.

  3. Effects of soil heterogeneity on steady state soil water pressure head under a surface line source

    NASA Astrophysics Data System (ADS)

    Zhang, Z. Fred; Parkin, Gary W.; Kachanoski, R. Gary; Smith, James E.

    2002-07-01

    There are numerous analytical solutions available for flow in unsaturated homogeneous porous media. In this paper, the stream tube model for one-dimensional water movement is extended to two-dimensional (2-D) water movement from a line source as the stream plane model. As well, new solutions are derived to predict the mean and variance of pressure head of water movement under a surface line source in heterogeneous soil using the perturbation method with first-order approximation (PM1) and with second-order approximation (PM2). A variance expression was also developed based on the spectral relationship presented by Yeh et al. [1985a]. The new solutions were tested using the 2-D stream plane model with parameters A = ln(α) and Y = ln(KS) and measurements from field experiments. Results show that the mean of steady state pressure head below the line source is not only a function of the mean parameter values but also a function of the variances of A and Y and the linear cross-correlation coefficient (ρ) between A and Y. The PM2 model can predict the mean pressure head accurately in heterogeneous soils at any level of correlation between A and Y, except when both the soil variability and ρ are high. The pressure head variance estimation based on the PM1 model predicts the measured variance well only when both the soil variability and ρ are low. The field experimental results show that both the PM1 and the spectral models give reasonable predictions of the pressure head variance. Both the measured and predicted values of the variance of pressure head using the two models increase with the depth of soil. Both models show that the variance of pressure head decreases as the source strength increases, but on average, the pressure head variance was underestimated by both models.

  4. The effect of nitrogen fertilization on soil surface CO2 fluxes in Siberian forest soils

    NASA Astrophysics Data System (ADS)

    Matvienko, Anastasia; Menyailo, Oleg

    2015-04-01

    Human activities, production of nitrogen fertilizers have altered the global nitrogen cycle greater than the carbon cycle. The purpose of our study was to investigate the effect of nitrogen application on the CO2 flux under two tree species - Siberian larch and Scots pine. To estimate nitrogen effect on heterotrophic and autotrophic components of soil respiration the three-year experiment with deep and shallow collars was carried out. Collars were installed in May of 2010. Nitrogen was applied in June of 2010 in the form of ammonium nitrate (dry) at the rate of 50 kg N/ha on the four replicated plots under both tree species. The emission of CO2 was measured every 2 weeks from May to October over three years with LI-8100A CO2 analyzer. Nitrogen application positively affected soil surface CO2 flux under both tree species. The effect of N was even significant for annual CO2 production. Under Scots pine, the N fertilization increased annual CO2 production during the first and second year of measurements, under larch only for the first year. For the third year the effect of N has disappeared under both tree species. The total losses of soil carbon due to N application were 600-650 kg C/ha under Siberian larch and three times higher (1800-2000 kg C/ha) under Scots pine. Different collar types revealed that the effect was mostly due to increased activity of heterotrophs and subsequent laboratory incubations proved that this activity was accelerated by N mostly in the litter layers. Overall, our results suggest that in N unpolluted Siberia, the application of N leads to soil C losses, mainly due to accelerated decomposition of forest floor. The losses of soil C might exceed N-driven C sequestration in tree biomass, negating thus positive effect of N addition on net C sequestration.

  5. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    USDA-ARS?s Scientific Manuscript database

    The objective of this paper is to study the feasibility of using a seismic surface wave method to investigate seasonal and weather effects on shallow surface soils. In the study, temporal variations of subsurface soil properties were measured and monitored by using a combination of a new seismic su...

  6. Uranium partition coefficients (Kd) in forest surface soil reveal long equilibrium times and vary by site and soil size fraction.

    PubMed

    Whicker, Jeffrey J; Pinder, John E; Ibrahim, Shawki A; Stone, James M; Breshears, David D; Baker, Kristine N

    2007-07-01

    The environmental mobility of newly deposited radionuclides in surface soil is driven by complex biogeochemical relationships, which have significant impacts on transport pathways. The partition coefficient (Kd) is useful for characterizing the soil-solution exchange kinetics and is an important factor for predicting relative amounts of a radionuclide transported to groundwater compared to that remaining on soil surfaces and thus available for transport through erosion processes. Measurements of Kd for 238U are particularly useful because of the extensive use of 238U in military applications and associated testing, such as done at Los Alamos National Laboratory (LANL). Site-specific measurements of Kd for 238U are needed because Kd is highly dependent on local soil conditions and also on the fine soil fraction because 238U concentrates onto smaller soil particles, such as clays and soil organic material, which are most susceptible to wind erosion and contribute to inhalation exposure in off-site populations. We measured Kd for uranium in soils from two neighboring semiarid forest sites at LANL using a U.S. Environmental Protection Agency (EPA)-based protocol for both whole soil and the fine soil fraction (diameters<45 microm). The 7-d Kd values, which are those specified in the EPA protocol, ranged from 276-508 mL g-1 for whole soil and from 615-2249 mL g-1 for the fine soil fraction. Unexpectedly, the 30-d Kd values, measured to test for soil-solution exchange equilibrium, were more than two times the 7-d values. Rates of adsorption of 238U to soil from solution were derived using a 2-component (FAST and SLOW) exponential model. We found significant differences in Kd values among LANL sampling sites, between whole and fine soils, and between 7-d and 30-d Kd measurements. The significant variation in soil-solution exchange kinetics among the soils and soil sizes promotes the use of site-specific data for estimates of environmental transport rates and suggests

  7. Spatio-temporal distribution of soil surface moisture in a heterogeneously farmed Mediterranean catchment

    NASA Astrophysics Data System (ADS)

    Hébrard, O.; Voltz, M.; Andrieux, P.; Moussa, R.

    2006-09-01

    SummaryObservation and interpretation of spatial soil surface moisture patterns are fundamental to spatially distributed modelling of runoff generation, soil evaporation, and plant transpiration. Compared to natural basins, man-made managements in farmed basins, such as field limits, agricultural practices and the networks of ditches, lead to great spatial heterogeneity in hydrological processes at the catchment scale. The aim of this study was to identify the factors controlling the spatio-temporal variability of the surface soil moisture in the farmed Mediterranean catchment of Roujan (0.91 km 2) located in southern France. Intensive measurements of soil moisture patterns were recorded during two drying sequences, respectively, in dry and wet seasons. Results show that the soil surface characteristics (SSC), which result in part from the agricultural practices such as soil tillage, chemical weed control or grass covering, are the main factors controlling the spatio-temporal distribution of the soil surface moisture during both the wet and dry drying sequences. However, in this study, none of the local factors such as the soil insolation (sunlight reaching soil surface through the plant canopy if there is one), the slope, the aspect and the soil texture is correlated to the soil moisture spatial variability. Only local factors control the spatio-temporal variability of soil surface moisture because agricultural operations like tillage influence greatly the local surface runoff by altering soil hydrologic properties. Also, the ditch networks influence the water transfer from the fields to the catchment outlet by routing runoff directly to the catchment outlet without modifying the soil surface moistures of downslope fields. Consequently, in farmed catchments the agricultural managements and practices strongly modify the spatio-temporal soil moisture distribution and must be taken into account in the understanding and in the modelling of hydrological processes.

  8. Effects of soil surface roughness on interrill erosion processes and sediment particle size distribution

    NASA Astrophysics Data System (ADS)

    Ding, Wenfeng; Huang, Chihua

    2017-10-01

    Soil surface roughness significantly impacts runoff and erosion under rainfall. Few previous studies on runoff generation focused on the effects of soil surface roughness on the sediment particle size distribution (PSD), which greatly affects interrill erosion and sedimentation processes. To address this issue, a rainfall-simulation experiment was conducted with treatments that included two different initial soil surface roughnesses and two rainfall intensities. Soil surface roughness was determined by using photogrammetric method. For each simulated event, runoff and sediment samples were collected at different experimental times. The effective (undispersed) PSD of each sediment sample and the ultimate (after dispersion) PSD were used to investigate the detachment and transport mechanisms involved in sediment movement. The results show that soil surface roughness significantly delayed runoff initiation, but had no significant effect on the steady runoff rate. However, a significant difference in the soil loss rate was observed between the smooth and rough soil surfaces. Sediments from smooth soil surfaces were more depleted in clay-size particles, but more enriched in sand-size particles than those from rough soil surfaces, suggesting that erosion was less selective on smooth than on rough soil surfaces. The ratio of different sizes of transported sediment to the soil matrix indicates that most of the clay was eroded in the form of aggregates, silt-size particles were transported mainly as primary particles, and sand-size particles were predominantly aggregates of finer particles. Soil surface roughness has a crucial effect on the sediment size distribution and erosion processes. Significant differences of the enrichment ratios for the effective PSD and the ultimate PSD were observed under the two soil surface roughness treatments. These findings demonstrate that we should consider each particle size separately rather than use only the total sediment discharge in

  9. Soil surface morphology evolution under spatiallynon-uniform rainfall

    NASA Astrophysics Data System (ADS)

    Cheraghi, M.; Rinaldo, A.; Sander, G. C.; Barry, D. A.

    2016-12-01

    We evaluated the applicability of a large-scale river network evolution modelused to simulate morphological changes of a laboratory-scale landscape onwhich there were no visible rills. Previously, such models were used onlyat the landscape scale, or in laboratory experiments where rills form in thesoils surface. The flume-scale experiment (1-m × 2-m surface area) was de-signed to allow model calibration. Low-cohesive fine sand was placed in theflume while the slope and relief height were 5% and 25 cm, respectively.Non-uniform rainfall with an average intensity of 85 mmh -1 and a stan-dard deviation of 26% was applied to the sediment surface for 16 h. Highresolution Digital Elevation Models were captured at intervals during theexperiment. Estimates of the overland flow drainage network were derivedand, using these, the river network evolution model was numerically solvedand calibrated. A noticeable feature of the experiment was a steep transitionzone in soil elevation that migrated upstream during the experiment. Physi-cally, this zone indicates where the shear stress is sufficient to cause sediment1erosion. The model was calibrated during the first 4 h of experiment. Af-terwards, it predicted the subsequent 12 h of measured surface morphologychanges. Therefore, the applicability of the landscape evolution model wasextended for non-uniform rainfall and in absence of visible rills.Keywords:Numerical simulation, Particle Swarm Optimization, Sediment transport,River network evolution model.

  10. Comparing soil and pond ash feedlot pen surfaces for environmental management

    USDA-ARS?s Scientific Manuscript database

    Removing manure and replacing soil to maintain pen surfaces is expensive. Pond ash (PA), a coal-fired electrical generation by-product, has good support qualities. A study was conducted comparing the performance of pond ash (PA) surfaced pens with soil surface (SS) pens. Four pens of an eight pen se...

  11. Controls on deep versus near-surface soil CO2 production and soil organic matter turnover (Invited)

    NASA Astrophysics Data System (ADS)

    SIX, J. W.; Berhe, A.; Yanni, S.; Gillabel, J.; van oost, K.

    2013-12-01

    At the soil profile scale, driving factors of decomposition and C turnover can change independently with depth, making a depth-specific assessment of controlling factors, such as temperature, dry-wet cycles, and vertical soil movement, is essential. In a set of depth explicit experiments and modeling exercises, we have tried to elucidate the effects of these controlling factors within the soil profile. In a first experiment, we combined 13C- and 14C-methodology with fractionation techniques to assess the C turnover of labile versus resistant C across the soil profile. As expected, the turnover of labile C increased drastically with increasing soil depth and had a Q10 of 2.8 in the surface layer. In a second experiment, we measured CO2, O2, temperature, and soil water content in two plots at 15, 30, 50, 70, and 90 cm depths to further elucidate the temperature sensitivity of soil C across the profile. Under non-limiting moisture (θ>20%) the Q10 value for the A horizon was 5.3 decreasing to 1.3 at θ<10%. In the C2 horizon at θ>20%, Q10 was 3.1 indicating that it is less sensitive to temperature variations than topsoil when moisture is non-limiting. In a follow-up third experiment, we conducted a wetting and drying experiment to assess the effect of changing moisture regimes on deep soil C dynamics. We found that soil CO2 production across the soil profile was more sensitive to changes in soil moisture during the drying than wetting phases, especially in the top 30 cm of soil. On the contrary, soil CO2 production across the soil profile was more sensitive to changes in soil temperature during wetting than drying phase. Deep soil CO2 production was significantly more sensitive to changes in temperature during the wetting phase, compared to SOM in topsoil layers. Finally, we developed a depth-explicit SOM model based on carbon isotopes and radionuclides. We found that it was essential to include vertical soil transport and its depth attenuation in order to correctly

  12. Spatial and temporal dynamics of soil-surface carbon dioxide emissions in bioenergy corn rotations and reconstructed prairies

    USDA-ARS?s Scientific Manuscript database

    Soil-surface CO2 efflux is a major export of carbon from the soil system. The interest in bioenergy cropping systems has raised questions as to the potential of management strategies to deteriorate soil carbon pools and soil quality. The objective of this research was to evaluate dynamic soil-surfac...

  13. Nocturnal soil CO2 uptake and its relationship to sub-surface soil and ecosystem carbon fluxes in a Chihuahuan Desert shrubland

    USDA-ARS?s Scientific Manuscript database

    Despite their prevalence, little attention has been given to quantifying aridland soil and ecosystem carbon fluxes over prolonged, annually occurring dry periods. We measured surface soil respiration (Rsoil), volumetric soil moisture and temperature in inter- and under-canopy soils, sub-surface soi...

  14. Improved Numerical Implementation of the Bounding Surface Plasticity Model for Cohesive Soils.

    DTIC Science & Technology

    1985-12-01

    STOR,SIGT4, $ EPM ,DSIGM,DEPI,UB,DLTAU,DBAR,DTAN,DSIGO) 4: Si.ubroutine to evaluate Yannis Dafalias’ bounding 11 surface plasticity model for clay soils ...AD-Ai63 572 IMPROVED NUMERICAL IMPLEMENTATION OF THE BOUNDING i/i SURFACE PLASTICITY MODEL FOR COHESIVE SOILS (U) CALIFORNIA UNIV DAVIS L R HERRMANN...Engineering Command ,, IMPROVED NUMERICAL SIMPLEMENTATION OF THE 𔃻 BOUNDING SURFACE PLASTICITY MODEL FOR COHESIVE SOILS -8STRACT A substantially more

  15. Intra-rainfall soil surface change detection using close-range photogrammetry

    NASA Astrophysics Data System (ADS)

    Bauer, Thomas; James, Michael R.; McShane, Gareth; Quinton, John N.; Strauss, Peter

    2015-04-01

    During precipitation events, the physical properties of soil surfaces change significantly. Such changes influence a large range of processes, e.g. surface runoff, soil erosion, water infiltration, soil-atmosphere interactions and plant growth. It has been proven that successive precipitation events change soil surfaces, but detailed studies on soil surface change within a single rainfall event do, to the best of our knowledge, not exist, due to a lack of suitable methods. However, recent developments in the use of photogrammetry are becoming a common tool in geoscience and can be utilized in soil surface detection. New concepts, developments in hardware and software allow a quick and user friendly calculation of surface models with close-range imagery and processing based on structure from motion (SfM) approaches. In this study we tested the potential of close range photogrammetry for detecting changes in soil surface topography within an artificial rainfall event. We used a photogrammetric approach to capture multiple images of the soil surface on two different soil types (loamy and sandy soil) under laboratory conditions while they were exposed to a 60 minute duration 47(60) mm hr-1 intensity rainfall event from a gravity driven rainfall simulator. The photographs were processed using Photoscan to produce point clouds which were then interpolated to produce DEM surfaces. Of the 126 surfaces produced during the rainfall event 125 were usable and able to demonstrate changes with a resolution of <1 mm in the z dimension and with a xy resolution of <0.5 mm. We demonstrate the potential of photogrammetry for surface detection within a precipitation event. The use of close-range photogrammetry opens new possibilities to monitor soil surfaces and could be developed for a range of other applications. Our results have the potential to lead to better understanding of infiltration, runoff, nutrient transport and soil erosion processes within precipitation event.

  16. Seed reserves diluted during surface soil reclamation in eastern Mojave Desert

    USGS Publications Warehouse

    Scoles-Sciulla, S. J.; DeFalco, L.A.

    2009-01-01

    Surface soil reclamation is used to increase the re-establishment of native vegetation following disturbance through preservation and eventual replacement of the indigenous seed reserves. Employed widely in the mining industry, soil reclamation has had variable success in re-establishing native vegetation in arid and semi-arid regions. We tested whether variable success could be due in part to a decrease of seed reserves during the reclamation process by measuring the change in abundance of germinable seed when surface soil was mechanically collected, stored in a soil pile for 4 months, and reapplied upon completion of a roadway. Overall seed reserve declines amounted to 86% of the original germinable seed in the soil. The greatest decrease in seed reserves occurred during soil collection (79% of original reserves), compared to the storage and reapplication stages. At nearby sites where stored surface soil had been reapplied, no perennial plant cover occurred from 0.5 to 5 years after application and <1% cover after 7 years compared to 5% cover in nearby undisturbed areas. The reduction in abundance of germinable seed during reclamation was primarily due to dilution of seed reserves when deeper soil fractions without seed were mixed with the surface soil during collection. Unless more precise techniques of surface soil collection are utilized, soil reclamation alone as a means for preserving native seed reserves is a method ill-suited for revegetating disturbed soils with a shallow seed bank, such as those found in the Mojave Desert. Copyright ?? Taylor & Francis Group, LLC.

  17. Influence of weed mat and surface sawdust mulch on soil nutrient availability and soil chemical properties under organic blueberry production

    USDA-ARS?s Scientific Manuscript database

    Weed control represents one of the most important cultural management aspects for organic blueberry production. Two of the most common ways to control weeds in blueberries is by the use of surface sawdust mulch or by landscape fabric, often referred to as weed mat. Soil temperature and soil moisture...

  18. On the soil roughness parameterization problem in soil moisture retrieval of bare surfaces from Synthetic Aperture Radar 1959

    USDA-ARS?s Scientific Manuscript database

    Synthetic Aperture Radar has shown its large potential for retrieving soil moisture maps at regional scales. However, since the backscattered signal is determined by several surface characteristics, the retrieval of soil moisture is an ill-posed problem when using single configuration imagery. Unles...

  19. Effects of Near Soil Surface Characteristics on the Soil Detachment Process in a Chronological Series of Vegetation Restoration

    NASA Astrophysics Data System (ADS)

    Wang, Bing

    2017-04-01

    The effects of near soil surface characteristics on the soil detachment process might be different at different stages of vegetation restoration. This study was performed to investigate the effects of the near soil surface factors of plant litter, biological soil crusts (BSCs), dead roots and live roots on the soil detachment process by overland flow at different stages of restoration. Soil samples (1 m long, 0.1 m wide, and 0.05 m high) under four treatment conditions were collected from 1-yr-old and 24-yr-old natural grasslands and subjected to flow scouring under five different shear stresses ranging from 5.3 to 14.6 Pa. The results indicated that the effects of near soil surface characteristics on soil detachment were substantial during the process of vegetation restoration. The total reduction in the soil detachment capacity of the 1-yr-old grassland was 98.1%, and of this total, 7.9%, 30.0% and 60.2% was attributed to the litter, BSCs and plant roots, respectively. In the 24-yr-old grassland, the soil detachment capacity decreased by 99.0%, of which 13.2%, 23.5% and 62.3% was caused by the litter, BSCs and plant roots, respectively. Combined with the previously published data of a 7-yr-old grassland, the influence of plant litter on soil detachment was demonstrated to increase with restoration time, but soil detachment was also affected by the litter type and composition. The role of BSCs was greater than that of plant litter in reducing soil detachment during the early stages of vegetation recovery. However, its contribution weakened with time since restoration. The influence of plant roots accounted for at least half or up to two-thirds of the total near soil surface factors, of which more than 72.6% was attributed to the physical binding effects of the roots. The chemical bonding effect of the roots increased with time since restoration and was greater than the effect of the litter on soil detachment in the late stages of vegetation restoration. The

  20. Comparison of remote measurements of infrared surface temperatures and microwave soil moisture

    NASA Technical Reports Server (NTRS)

    Perry, Eileen M.; Carlson, Toby N.

    1987-01-01

    Scatterometric measurements of active microwave soil water content and radiometric measurements of thermal IR surface temperatures were made simultaneously fron an aircraft flying 400 m over an agricultural region of France after harvesting. The surface temperatures were used to deterine soil moisture availability estimates according to the Carlson (1986) model. Surface temperature or soil moisture availability and microwave soil moisture were correlated. The standard error in the IR temperature and soil moisture availability due to influences other than soil moisture is found to be + or - 2 C. The standard deviation of the temperature/moisture availability is greater than this standard error. It is shown that correlations between soil water content and moisture availability improve with increasing spatial or temporal variance in the measure surface temperatures.

  1. Characterization Investigation Study: Volume 3, Radiological survey of surface soils

    SciTech Connect

    Solow, A.J.; Phoenix, D.R.

    1987-12-01

    The Feed Materials Production Center was constructed to produce high purity uranium metal for use at various Department of Energy facilities. The waste products from these operations include general uncontaminated scrap and refuse, contaminated and uncontaminated metal scrap, waste oils, low-level radioactive waste, co-contaminated wastes, mixed waste, toxic waste, sludges from water treatment, and fly ash from the steam plant. This material is estimated to total more than 350,000 cubic meters. Other wastes stored in this area include laboratory chemicals and other combustible materials in the burn pit; fine waste stream sediments in the clear well; fly ash and waste oils in the two fly ash areas; lime-alum sludges and boiler plant blowdown in the lime sludge ponds; and nonradioactive sanitary waste, construction rubble, and asbestos in the sanitary landfill. A systematic survey of the surface soils throughout the Waste Storage Area, associated on-site drainages, and the fly ash piles was conducted using a Field Instrument for Detecting Low-Energy Radiation (FIDLER). Uranium is the most prevalent radioactive element in surface soil; U-238 is the principal radionuclide, ranging from 2.2 to 1790 pCi/g in the general Waste Storage Area. The maximum values for the next highest activity concentrations in the same area were 972 pCi/g for Th-230 and 298 pCi/g for U-234. Elevated activity concentrations of Th-230 were found along the K-65 slurry line, the maximum at 3010 pCi/g. U-238 had the highest value of 761 pCi/g in the drainage just south of pit no. 5. The upper fly ash area had the highest radionuclide activity concentrations in the surface soils with the maximum values for U-238 at 8600 pCi/g, U-235 at 2190 pCi/g, U-234 at 11,400 pCi/g, Tc-99 at 594 pCi/g, Ra-226 at 279 pCi/g, and Th-230 at 164 pCi/g.

  2. Baseline concentrations of 15 trace elements in Florida surface soils

    SciTech Connect

    Chen, M.; Ma, L.Q.; Harris, W.G.

    1999-08-01

    The objective of this study was to establish baseline concentrations for 15 potentially toxic elements (Ag, As, Ba, Be, Cd, Cr, cu, Hg, Ma, Mo, Ni, Pb, Sb, Se, and Zn) based on 448 representative Florida surface soils using microwave assisted HNO{sub 3}-HCl-HF digestion. Baseline concentrations of those elements were (mg kg{sup {minus}1}): Ag 0.07-2.50, As 0.02-7.01, Ba 1.67-112, Be 0.04-4.15, Cd 0-0.33, Cr 0.89-80.7, Cu 0.22-21.9, Hg 0.00075-0.0396, Mo 0.13-6.76, Ni 1.70-48.5, Pb 0.69-42.0, Sb 0.06-0.79, Se 0.01-1.11, and Zn 0.89-29.6, respectively. Upper baseline values for most elements corresponded with these reported in literature, except Ba, Hg, Mn, Sb, and Zn, which were 3 to 23 times lower. Soil properties, including pH, organic carbon (OC), particle size, cation-exchange capacity (CEC), available water, extractable base, extractable acidity, total Ca, Mg, P, K, Fe, and Al concentrations, were related to metal concentrations using factorial analysis. Eight factors were identified (total Fe and Al, CEC, pH, clay, OC, total Ni and Mo, total Sb and Pb, and total Hg) and accounted for 87% of the total variance, suggesting that metal concentrations were primarily controlled by soil compositions. Multiple regression of elemental concentrations against total Fe, total Al, clay, OC, CEC, and pH was significant for all elements. Partial correlation coefficients indicated that total Fe and/or Al explained most of the variance for Mn, Ni, Ba, Be, Hg, As, Cd, Cr, Cu, Mo, Pb, and Zn concentrations. Most of the variance in Se was related to clay, whereas those of Ag and Sb related to clay and total Al.

  3. Effect of soil surface conditions on runoff velocity and sediment mean aggregate diameter

    NASA Astrophysics Data System (ADS)

    César Ramos, Júlio; Bertol, Ildegardis; Paz González, Antonio; de Souza Werner, Romeu; Marioti, Juliana; Henrique Bandeira, Douglas; Andrighetti Leolatto, Lidiane

    2013-04-01

    Soil cover and soil management are the factors that most influence soil erosion by water, because they directly affect soil surface roughness and surface cover. The main effect of soil cover by crop residues consists in dissipation of kinetic energy of raindrops and also partly kinetic energy of runoff, so that the soil disaggregation is considerably reduced but, in addition, soil cover captures detached soil particles, retains water on its surface and decreases runoff volume and velocity. In turn, soil surface roughness, influences soil surface water storage and infiltration and also runoff volume and velocity, sediment retention and subsequently water and sediment losses. Based on the above rationale, we performed a field experiment to assess the influence of soil cover and soil surface roughness on decay of runoff velocity as well as on mean diameter of transported sediments (D50 index). The following treatments were evaluated: SRR) residues of Italian ryegrass (Lolium multiflorum) on a smooth soil surfcace, SRV) residues of common vetch (Vicia sativa) on a smooth soil surface, SSR) scarification after cultivation of Italian ryegrass resulting in a rough surface, SSV) scarification after cultivation of common vetch resulting in a rough surface, and SBS) scarified bare soil with high roughness as a control. The field experiments was performed on an Inceptisol in South Brazil under simulated rainfall conditions during 2012. Experimental plots were 11 m long and 3.5 m wide with an area of 38.5 m2. Six successive simulated rainfall tests were applied using a rotating-boom rain simulator. During each test, rain intensity was 60 mmhr-1, whereas rain duration was 90 minutes. Runoff velocity showed no significant differences between cultivated treatments. However, when compared to bare soil treatment, SBS (0.178 m s-1) and irrespective of the presence of surface crop residues or scarification operations, cultivated soil treatments significantly reduced runoff velocity

  4. Explosive particle soil surface dispersion model for detonated military munitions.

    PubMed

    Hathaway, John E; Rishel, Jeremy P; Walsh, Marianne E; Walsh, Michael R; Taylor, Susan

    2015-07-01

    The accumulation of high explosive mass residue from the detonation of military munitions on training ranges is of environmental concern because of its potential to contaminate the soil, surface water, and groundwater. The US Department of Defense wants to quantify, understand, and remediate high explosive mass residue loadings that might be observed on active firing ranges. Previously, efforts using various sampling methods and techniques have resulted in limited success, due in part to the complicated dispersion pattern of the explosive particle residues upon detonation. In our efforts to simulate particle dispersal for high- and low-order explosions on hypothetical firing ranges, we use experimental particle data from detonations of munitions from a 155-mm howitzer, which are common military munitions. The mass loadings resulting from these simulations provide a previously unattained level of detail to quantify the explosive residue source-term for use in soil and water transport models. In addition, the resulting particle placements can be used to test, validate, and optimize particle sampling methods and statistical models as applied to firing ranges. Although the presented results are for a hypothetical 155-mm howitzer firing range, the method can be used for other munition types once the explosive particle characteristics are known.

  5. Characterising soil surface condition and carbon vulnerability using spatial statistics and directional reflectance

    NASA Astrophysics Data System (ADS)

    Croft, H.; Anderson, K.

    2008-12-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of Soil Organic Matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to soil organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness, indicating that a physical soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Remotely sensed data can provide a cost- effective means of monitoring changes in soil surface condition over broad spatial extents. Growing recognition of the importance of the directional reflectance domain has highlighted their potential application for monitoring changes in soil surface roughness, associated with the breakdown of macro-aggregates and therefore SOM release. This is particularly relevant for soil condition monitoring because during soil structural degradation, changes in the self-shadowing effects of soil aggregates has a measurable effect on directional reflectance factors measured by proximal remote sensing devices. Field and laboratory data are therefore required for an empirical understanding of soil directional reflectance, underpinning subsequent model development. This experiment details the use of hyperspectral multiple view angle, proximal reflectance data (400-2500 nm) for describing changes in soil surface structure. Five different soil crusting states were produced, simulating a progressive decline in soil surface structure using artificial rainfall. Each stage was characterised using a close-range laser scanning device with a 2 mm spatial sampling methodology. Data were analysed within a geostatistical framework, where variogram analysis quantitatively confirmed the change in soil surface structure during crusting (sill variance = 0

  6. Sagebrush wildfire effects on surface soil nutrient availability: A temporal and spatial study

    USDA-ARS?s Scientific Manuscript database

    Wildfires occurring in Artemisia (sagebrush) ecosystems can temporarily increase soil nutrient availability in surface soil. Less is known, however, on how soil nutrient availability changes over time and microsite location post-wildfire. In Oct., 2013 a wildfire approximately 30 km north of Reno, N...

  7. The SMAP level 4 surface and root zone soil moisture data assimilation product

    USDA-ARS?s Scientific Manuscript database

    The NASA Soil Moisture Active Passive (SMAP) mission is scheduled for launch in January 2015 and will provide L-band radar and radiometer observations that are sensitive to surface soil moisture (in the top few centimeters of the soil column). For several of the key applications targeted by SMAP, ho...

  8. Composition and method for cleaning embedded soil from surfaces having low gloss coatings

    NASA Astrophysics Data System (ADS)

    Clark, K. G.

    1984-04-01

    A composition for cleaning embedded soil from surfaces coated with flat or low-gloss coatings has elastomeric particles intermixed with a thixotropic solvent emulsion cleaner. The elastomeric particles provide an eraser-like action to absorb deeply entrapped soil so that the cleaner can emulsify or dissolve the soil and wash it away.

  9. Calibration and validation of the COSMOS rover for surface soil moisture

    USDA-ARS?s Scientific Manuscript database

    The mobile COsmic-ray Soil Moisture Observing System (COSMOS) rover may be useful for validating satellite-based estimates of near surface soil moisture, but the accuracy with which the rover can measure 0-5 cm soil moisture has not been previously determined. Our objectives were to calibrate and va...

  10. Alternative Penetrometers to Measure the Near Surface Strength of Soft Seafloor Soils

    DTIC Science & Technology

    2012-09-30

    Strength of Soft Seafloor Soils Mark R. Tufenkjian Department of Civil Engineering, California State University, Los Angeles 5151 State University... seafloor soils. Further the education of participating undergraduate and graduate students by active involvement in research and mentoring activities...surface shear strength of soft seafloor soils. APPROACH Review current full-flow penetrometer technology: Review technical literature to evaluate

  11. Evaluation of Two Methods for Determining Surface Soil Moisture from Radar Imagery

    NASA Astrophysics Data System (ADS)

    Thoma, D.; Moran, M.; Bryant, R.; Holifield, C.; Skirvin, S.; Rahman, M.; Kershner, C.; Watts, J.; Slocum, K.

    2003-12-01

    Distributed soil moisture data are useful for determining cross-country mobility, irrigation scheduling, pest management strategy, biomass production and potential for soil erosion and infiltration. Large area monitoring of surface soil moisture (to depths of 5 cm) is possible with radar remote sensing techniques, but accuracy must be assessed before it can be implemented operationally. Two methods for predicting surface soil moisture from radar satellite imagery were tested in sparsely vegetated, semi-arid Arizona rangelands. In the first approach, the Integral Equation Method (IEM) model was run in the forward direction to generate a Look-Up-Table (LUT) of radar backscatter for the expected range of surface roughness and moisture content in the study area. The LUT was used to derive surface soil moisture estimates from radar images acquired at the study site. In the second approach, a difference index was made from time series differences in radar backscatter signals from wet and dry soils. The difference index minimized variations in surface roughness and resulted in a direct relation between difference and surface soil moisture. For both approaches, results were validated against in situ measurements of surface soil moisture at 46 sites with dielectric probes at the time of satellite overpass. The modeling approach requires surface roughness inputs which may be difficult to obtain, whereas the difference technique requires only a dry surface reference backscatter for comparison with wetter surface backscatter to determine moisture content.

  12. A physical scaling model for aggregation and disaggregation of field-scale surface soil moisture dynamics.

    PubMed

    Ojha, Richa; Govindaraju, Rao S

    2015-07-01

    Scaling relationships are needed as measurements and desired predictions are often not available at concurrent spatial support volumes or temporal discretizations. Surface soil moisture values of interest to hydrologic studies are estimated using ground based measurement techniques or utilizing remote sensing platforms. Remote sensing based techniques estimate field-scale surface soil moisture values, but are unable to provide the local-scale soil moisture information that is obtained from local measurements. Further, obtaining field-scale surface moisture values using ground-based measurements is exhaustive and time consuming. To bridge this scale mismatch, we develop analytical expressions for surface soil moisture based on sharp-front approximation of the Richards equation and assumed log-normal distribution of the spatial surface saturated hydraulic conductivity field. Analytical expressions for field-scale evolution of surface soil moisture to rainfall events are utilized to obtain aggregated and disaggregated response of surface soil moisture evolution with knowledge of the saturated hydraulic conductivity. The utility of the analytical model is demonstrated through numerical experiments involving 3-D simulations of soil moisture and Monte-Carlo simulations for 1-D renderings-with soil moisture dynamics being represented by the Richards equation in each instance. Results show that the analytical expressions developed here show promise for a principled way of scaling surface soil moisture.

  13. Using Remote Sensing Platforms to Estimate Near-Surface Soil Properties

    NASA Technical Reports Server (NTRS)

    Sullivan, D. G.; Shaw, J. N.; Rickman, D.; Mask, P. L.; Wersinger, J. M.; Luvall, J.

    2003-01-01

    Evaluation of near-surface soil properties via remote sensing (RS) could facilitate soil survey mapping, erosion prediction, fertilization regimes, and allocation of agrochemicals. The objective of this study was to evaluate the relationship between soil spectral signature and near surface soil properties in conventionally managed row crop systems. High resolution RS data were acquired over bare fields in the Coastal Plain, Appalachian Plateau, and Ridge and Valley provinces of Alabama using the Airborne Terrestrial Applications Sensor (ATLAS) multispectral scanner. Soils ranged from sandy Kandiudults to fine textured Rhodudults. Surface soil samples (0-1 cm) were collected from 163 sampling points for soil water content, soil organic carbon (SOC), particle size distribution (PSD), and citrate dithionite extractable iron (Fed) content. Surface roughness, soil water content, and crusting were also measured at sampling. Results showed RS data acquired from lands with less than 4 % surface soil water content best approximated near-surface soil properties at the Coastal Plain site where loamy sand textured surfaces were predominant. Utilizing a combination of band ratios in stepwise regression, Fed (r2 = 0.61), SOC (r2 = 0.36), sand (r2 = 0.52), and clay (r2 = 0.76) were related to RS data at the Coastal Plain site. In contrast, the more clayey Ridge and Valley soils had r-squares of 0.50, 0.36, 0.17, and 0.57. for Fed, SOC, sand and clay, respectively. Use of estimated eEmissivity did not generally improve estimates of near-surface soil attributes.

  14. Using Remote Sensing Platforms to Estimate Near-Surface Soil Properties

    NASA Technical Reports Server (NTRS)

    Sullivan, D. G.; Shaw, J. N.; Rickman, D.; Mask, P. L.; Wersinger, J. M.; Luvall, J.

    2003-01-01

    Evaluation of near-surface soil properties via remote sensing (RS) could facilitate soil survey mapping, erosion prediction, fertilization regimes, and allocation of agrochemicals. The objective of this study was to evaluate the relationship between soil spectral signature and near surface soil properties in conventionally managed row crop systems. High resolution RS data were acquired over bare fields in the Coastal Plain, Appalachian Plateau, and Ridge and Valley provinces of Alabama using the Airborne Terrestrial Applications Sensor (ATLAS) multispectral scanner. Soils ranged from sandy Kandiudults to fine textured Rhodudults. Surface soil samples (0-1 cm) were collected from 163 sampling points for soil water content, soil organic carbon (SOC), particle size distribution (PSD), and citrate dithionite extractable iron (Fed) content. Surface roughness, soil water content, and crusting were also measured at sampling. Results showed RS data acquired from lands with less than 4 % surface soil water content best approximated near-surface soil properties at the Coastal Plain site where loamy sand textured surfaces were predominant. Utilizing a combination of band ratios in stepwise regression, Fed (r2 = 0.61), SOC (r2 = 0.36), sand (r2 = 0.52), and clay (r2 = 0.76) were related to RS data at the Coastal Plain site. In contrast, the more clayey Ridge and Valley soils had r-squares of 0.50, 0.36, 0.17, and 0.57. for Fed, SOC, sand and clay, respectively. Use of estimated eEmissivity did not generally improve estimates of near-surface soil attributes.

  15. Soil Surface Moisture from Cryosat2 and Sentinel-3 Satellite Radar Altimetry

    NASA Astrophysics Data System (ADS)

    Berry, P. A. M.; Balmbra, R.

    2016-08-01

    Measuring soil moisture using remote sensing techniques has been a key application for many years; however, these techniques encounter difficulties in arid and semi-arid terrain. Satellite altimetry presents an attractive option for retrieval of soil surface moisture in these areas [1:2]. Surface soil moisture has now been successfully retrieved from Cryosat2 data as part of the EU LOTUS project; the key to retrieving accurate soil surface moisture estimates is the development of very detailed Dry Earth Models (DREAMS). Soil moisture time series have been derived from Cryosat2 and Jason2 data over the Simpson, Tenere and Kalahari deserts; cross-comparison of the results and validation with independent remote sensed soil moisture data is presented. These results show that the detailed along- track estimates that can be achieved from satellite radar altimetry have a unique contribution to make to soil moisture retrieval in arid and semi-arid terrain.

  16. Improved Prediction of Quasi-Global Vegetation Conditions Using Remotely-Sensed Surface Soil Moisture

    NASA Technical Reports Server (NTRS)

    Bolten, John; Crow, Wade

    2012-01-01

    The added value of satellite-based surface soil moisture retrievals for agricultural drought monitoring is assessed by calculating the lagged rank correlation between remotely-sensed vegetation indices (VI) and soil moisture estimates obtained both before and after the assimilation of surface soil moisture retrievals derived from the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) into a soil water balance model. Higher soil moisture/VI lag correlations imply an enhanced ability to predict future vegetation conditions using estimates of current soil moisture. Results demonstrate that the assimilation of AMSR-E surface soil moisture retrievals substantially improve the performance of a global drought monitoring system - particularly in sparsely-instrumented areas of the world where high-quality rainfall observations are unavailable.

  17. Metal redistribution by surface casting of four earthworm species in sandy and loamy clay soils.

    PubMed

    Zorn, Mathilde I; van Gestel, Cornelis A M; Eijsackers, Herman J P

    2008-12-01

    Bioturbation of metal contaminated soils contributes considerably to redistribution and surfacing of contaminated soil from deeper layers. To experimentally measure the contribution of Allolobophora chlorotica, Aporrectodea caliginosa, Lumbricus rubellus and L. terrestris to soil surface casting, a time-course experiment was performed under laboratory conditions. Earthworms were incubated in perspex columns filled with sandy soil (2% organic matter, 2.9% clay) or loamy clay soil (15% organic matter, 20% clay), and surface casts were collected after up to 80 days. On the sandy soil, A. caliginosa and L. rubellus brought approximately 7.1-16 g dry wt. casts/g fresh wt. earthworm to the surface, which is significantly more than A. chlorotica and L. terrestris (2.5-5.0 g dry wt./g fresh wt.). A. caliginosa was the only species that produced significantly more surface casts in the sandy soil than in the loamy clay soil. In the loamy clay soil, no differences in biomass-corrected casting rates were found among the species. Surface casting rates tended to decrease after 20 days. Considering the densities of the different species in a Dutch floodplain area Afferdensche and Deestsche Waarden, surface cast production is estimated to amount to 2.0 kg dry soil/m2 after 80 days, which could be extrapolated to 2.7-9.1 kg/m2 per year. These amounts correspond to a surface deposition of a layer of approximately 1.9-6.5 mm/year, which is of the same order or even slightly higher than the sedimentation rate and much higher than the amount of soil brought to the soil surface by bioturbating small mammals.

  18. The use of physicochemical methods to detect organic food soils on stainless steel surfaces.

    PubMed

    Whitehead, K A; Benson, P; Smith, L A; Verran, J

    2009-11-01

    Food processing surfaces fouled with organic material pose problems ranging from aesthetic appearance, equipment malfunction and product contamination. Despite the importance of organic soiling for subsequent product quality, little is known about the interaction between surfaces and organic soil components. A range of complex and defined food soils was applied to 304 stainless steel (SS) surfaces to determine the effect of type and concentration of soil on surface physicochemical parameters, viz surface hydrophobicity (DeltaG(iwi)), surface free energy (gamma(s)), Lifshitz van der Waals (gamma_LW(s)), Lewis acid base (gamma_AB(s)), electron acceptor (gamma_+(s) ) and electron donor (gamma_-(s) ) measurements. When compared to the control surface, changes in gamma_AB(s), gamma_+(s) and gamma_-(s) were indicative of surface soiling. However, soil composition and surface coverage were heterogeneous, resulting in complex data being generated from which trends could not be discerned. These results demonstrate that the retention of food soil produces changes in the physicochemical parameters of the surface that could be used to indicate the hygienic status of a surface.

  19. Selection of soil hydraulic properties in a land surface model using remotely-sensed soil moisture and surface temperature

    NASA Astrophysics Data System (ADS)

    Shellito, P. J.; Small, E. E.; Gutmann, E. D.

    2013-12-01

    Synoptic-scale weather is heavily influenced by latent and sensible heating from the land surface. The partitioning of available energy between these two fluxes as well as the distribution of moisture throughout the soil column is controlled by a unique set of soil hydraulic properties (SHPs) at every location. Weather prediction systems, which use coupled land surface and atmospheric models in their forecasts, must therefore be parameterized with estimates of SHPs. Currently, land surface models (LSMs) obtain SHP values by assuming a correlation exists between SHPs and the soil type, which the USDA maps in 12 classes. This method is spurious because texture is only one control of many that affects SHPs. Alternatively, SHPs can be obtained by calibrating them within the framework of an LSM. Because remotely-sensed data have the potential for continent-wide application, there is a critical need to understand their specific role in calibration efforts and the extent to which such calibrated SHPs can improve model simulations. This study focuses on SHP calibration with soil moisture content (SMC) and land surface temperature (Ts), data that are available from the SMOS and MODIS satellite missions, respectively. The scientific goals of this study are: (1) What is the model performance tradeoff between weighting SMC and Ts differently during the calibration process? (2) What can the tradeoff between calibration using in-situ and remotely-sensed SMC reveal about SHP scaling? (3) How are these relationships influenced by climatic regime and vegetation type? (4) To what extent can calibrated SHPs improve model performance over that of texture-based SHPs? Model calibrations are carried out within the framework of the Noah LSM using the Shuffled Complex Evolution Metropolis (SCEM-UA) algorithm in five different climatic regimes. At each site, a five-dimensional parameter space of SHPs is searched to find the location that minimizes the difference between observed and

  20. Implementing a physical soil water flow model with minimal soil characteristics and added value offered by surface soil moisture measurements assimilation.

    NASA Astrophysics Data System (ADS)

    Chanzy, André

    2010-05-01

    climatic data. The strategy takes profit of all work made on soil texture as a proxi of soil hydraulic through pedotransfer functions. It also takes into account the constraints in soil moisture variations after important precipitation events. Performances on soil moisture are assessed by considering both the soil moisture accuracy and the ability of detecting a soil moisture threshold. o The added value of soil moisture measurements. The aim is to evaluate to which extent we can improve soil moisture simulations by assimilating a few soil moisture measurements made in the surface layer (ploughed layers). We focus on such a layer since moisture can be derived from remote sensing observations or by using in situ sensors (capacitance sensor, TDR) with minimal effort. The validity of such measurements to represent the soil moisture at the field scale is analysed. It is shown that relative variations in soil moisture are much easier to obtain than an absolute characterisation of the soil moisture measurements. We evaluate the value of assimilating surface measurement in the TEC model and how we can deal with a measurement of relative soil moisture variations (in order to prevent a tedious calibration process). Again the performances of the approach are evaluated with the soil moisture accuracy and the ability of detecting a soil moisture threshold.

  1. Role of soil health in maintaining environmental sustainability of surface coal mining.

    PubMed

    Acton, Peter M; Fox, James F; Campbell, J Elliott; Jones, Alice L; Rowe, Harold; Martin, Darren; Bryson, Sebastian

    2011-12-01

    Mountaintop coal mining (MCM) in the Southern Appalachian forest region greatly impacts both soil and aquatic ecosystems. Policy and practice currently in place emphasize water quality and soil stability but do not consider upland soil health. Here we report soil organic carbon (SOC) measurements and other soil quality indicators for reclaimed soils in the Southern Appalachian forest region to quantify the health of the soil ecosystem. The SOC sequestration rate of the MCM soils was 1.3 MgC ha(-1) yr(-1) and stocks ranged from 1.3 ± 0.9 to 20.9 ± 5.9 Mg ha(-1) and contained only 11% of the SOC of surrounding forest soils. Comparable reclaimed mining soils reported in the literature that are supportive of soil ecosystem health had SOC stocks 2.5-5 times greater than the MCM soils and sequestration rates were also 1.6-3 times greater. The high compaction associated with reclamation in this region greatly reduces both the vegetative rooting depth and infiltration of the soil and increases surface runoff, thus bypassing the ability of soil to naturally filter groundwater. In the context of environmental sustainability of MCM, it is proposed that the entire watershed ecosystem be assessed and that a revision of current policy be conducted to reflect the health of both water and soil.

  2. The Representation of Arctic Soils in the Land Surface Model: The Importance of Mosses.

    NASA Astrophysics Data System (ADS)

    Beringer, Jason; Lynch, Amanda H.; Chapin, F. Stuart, III; Mack, Michelle; Bonan, Gordon B.

    2001-08-01

    Mosses dominate the surface cover in high northern latitudes and have the potential to play a key role in modifying the thermal and hydrologic regime of Arctic soils. These modifications in turn feed back to influence surface energy exchanges and hence may affect regional climate. However, mosses are poorly represented in models of the land surface. In this study the NCAR Land Surface Model (LSM) was modified in two ways. First, additional soil texture types including mosses and lichens were added to more realistically represent northern soils. Second, the LSM was also modified so that a different soil texture type could be specified for each layer. Several experiments were performed using climate data from an Arctic tundra site in 1995. The model was run for a homogeneous loam soil column and then also for columns that included moss, lichen, peat, and sand. The addition of a surface layer of moss underlain by peat and loam had a substantial impact on modeled surface processes. First, moss acted as an insulative layer producing cooler summer temperatures (6.9°C lower at 0.5 m) and warmer winter temperatures (2.3°C higher at 0.5 m) when compared with a homogenous loam soil column. Second, a soil column with a moss surface had a greater surface infiltration, leading to greater storage of soil moisture in lower layers when compared with a homogeneous loam column. Last, moss modulated the surface energy exchanges by decreasing soil heat flux (57% in July) and increasing turbulent fluxes of heat (67% in July) and moisture (15% in July). Mosses were also more effective contributors to total latent heating than was a bare loam surface. These results suggest that the addition of moss and the ability to prescribe different soil textures for different soil layers result in a more plausible distribution of heat and water within the column and that these modifications should be incorporated into regional and global climate models.

  3. Evaluating soil evaporation parameterizations at near-instantaneous scales using surface dryness indices

    NASA Astrophysics Data System (ADS)

    Gao, Yanchun; Gan, Guojing; Liu, Maofeng; Wang, Jinfeng

    2016-10-01

    Soil evaporation is an important component in the water and energy cycles on land, especially for areas that are moderately or densely covered by bare soil. Soil evaporation parameterizations that scale down potential evaporation with the soil surface temperature (Ts) and/or the air humidity are regionally applicable because of the advantage of omitting pixel-scale near-surface soil moisture. In this paper, we provide an intercomparison study among these parameterizations. Potential evaporation indices are estimated from the Priestley-Taylor method, the Penman method, and the mass transfer method (with or without Ts). The surface dryness indices that indicate the water availability of the soil surface are based on Ts and/or the air humidity. We establish and evaluate ten such soil evaporation parameterizations through combinations of different types of potential evaporation indices and surface dryness indices at near-instantaneous scales (30 min). The results show that incorporating the soil temperature in the surface dryness index instead of the potential evaporation index can improve soil evaporation estimations. Poorer but still reasonable estimations are achieved when only the air humidity-based surface dryness index is used. In addition, the energy balance factor is crucial in the surface dryness indices. Our study indicates that the potential evaporation indices that are based on the Penman equation are generally more useful and robust than those that are based on the Priestley-Taylor approach or the mass transfer method. However, when the surface dryness index is only based on air humidity data, the Priestley-Taylor potential evaporation index performs as well as the index that is estimated from the Penman equation. In contrast, a soil evaporation parameterization that estimates the potential evaporation through the mass transfer method (with Ts) and the surface dryness index from the soil moisture content did not perform as well as the above ten

  4. High-resolution hydraulic parameter maps for surface soils in tropical South America

    NASA Astrophysics Data System (ADS)

    Marthews, T. R.; Quesada, C. A.; Galbraith, D. R.; Malhi, Y.; Mullins, C. E.; Hodnett, M. G.; Dharssi, I.

    2014-05-01

    Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded data sets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten-Mualem and van Genuchten-Burdine soil hydraulic models, which are widely used hydraulic sub-models in land surface models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain data base and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20x higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally parameterised and that are not just based on soil texture. We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.

  5. High-resolution hydraulic parameter maps for surface soils in tropical South America

    NASA Astrophysics Data System (ADS)

    Marthews, T. R.; Quesada, C. A.; Galbraith, D. R.; Malhi, Y.; Mullins, C. E.; Hodnett, M. G.; Dharssi, I.

    2013-12-01

    Modern land surface model simulations capture soil profile water movement through the use of soil hydraulics sub-models, but good hydraulic parameterisations are often lacking, especially in the tropics. We present much-improved gridded datasets of hydraulic parameters for surface soil for the critical area of tropical South America, describing soil profile water movement across the region to 30 cm depth. Optimal hydraulic parameter values are given for the Brooks and Corey, Campbell, van Genuchten-Mualem and van Genuchten-Burdine soil hydraulic models, which are widely-used hydraulic sub-models in Land Surface Models. This has been possible through interpolating soil measurements from several sources through the SOTERLAC soil and terrain database and using the most recent pedotransfer functions (PTFs) derived for South American soils. All soil parameter data layers are provided at 15 arcsec resolution and available for download, this being 20 × higher resolution than the best comparable parameter maps available to date. Specific examples are given of the use of PTFs and the importance highlighted of using PTFs that have been locally-parameterised and that are not just based on soil texture. Details are provided specifically on how to assemble the ancillary data files required for grid-based vegetation simulation using the Joint UK Land Environment Simulator (JULES). We discuss current developments in soil hydraulic modelling and how high-resolution parameter maps such as these can improve the simulation of vegetation development and productivity in land surface models.

  6. A long-term simulation of surface fluxes and soil moisture

    SciTech Connect

    Kim, J.; Lee, R.L.; Ek, M.

    1993-09-01

    The heat fluxes over land surfaces play important roles in shaping atmospheric flows on various temporal and spatial scales. Fast and McCorcle showed that sea-breeze-like mesoscale circulations can develop over land surfaces of heterogeneous soil type and soil moisture. Evaporation from land surfaces is one of the major moisture sources for the summertime convective precipitation in extratropics. General circulation model studies also indicate that surface characteristics cause a significant impact on the simulated climate.

  7. Soil surface CO2 fluxes and the carbon budget of a grassland

    NASA Technical Reports Server (NTRS)

    Norman, J. M.; Garcia, R.; Verma, S. B.

    1992-01-01

    Measurements of soil surface CO2 fluxes are reported for three sites within the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE) area, and simple empirical equations are fit to the data to provide predictions of soil fluxes from environmental observations. A prototype soil chamber, used to make the flux measurements, is described and tested by comparing CO2 flux measurements to a 40-L chamber, a 1-m/cu chamber, and eddy correlation. Results suggest that flux measurements with the prototype chamber are consistent with measurements by other methods to within about 20 percent. A simple empirical equation based on 10-cm soil temperature, 0- to 10-cm soil volumetric water content, and leaf area index predicts the soil surface CO2 flux with a rms error of 1.2 micro-mol sq m/s for all three sites. Further evidence supports using this equation to evaluate soil surface CO2 during the 1987 FIFE experiment. The soil surface CO2 fluxes when averaged over 24 hours are comparable to daily gross canopy photosynthetic rates. For 6 days of data the net daily accumulation of carbon is about 0.6 g CO2 sq m/d; this is only a few percent of the daily gross accumulation of carbon by photosynthesis. As the soil became drier in 1989, the net accumulation of carbon by the prairie increased, suggesting that the soil flux is more sensitive to temperature and drought than the photosynthetic fluxes.

  8. Effects of PV Module Soiling on Glass Surface Resistance and Potential-Induced Degradation

    SciTech Connect

    Hacke, Peter; Button, Patrick; Hendrickson, Alex; Spataru, Sergiu; Glick, Stephen

    2015-06-14

    The goals of the project were: Determine applicability of transmission line method (TLM) to evaluate sheet resistance of soils on module glass;
    Evaluate various soils on glass for changes in surface resistance and their ability to promote potential-induced degradation with humidity (PID);
    Evaluate PID characteristics, rate, and leakage current increases on full-size mc-Si modules associated with a conductive soil on the surface.

  9. Phosphorus solubility of agricultural soils: a surface charge and phosphorus-31 NMR speciation study

    USDA-ARS?s Scientific Manuscript database

    We investigated ten soils from six states in United States to determine the relationship between potentiometric titration derived soil surface charge and Phosphorus-31 (P) nuclear magnetic resonance (NMR) speciation with the concentration of water-extractable P (WEP). The surface charge value at the...

  10. Role of Subsurface Physics in the Assimilation of Surface Soil Moisture Observations

    NASA Technical Reports Server (NTRS)

    Reichle, R. H.

    2010-01-01

    Root zone soil moisture controls the land-atmosphere exchange of water and energy and exhibits memory that may be useful for climate prediction at monthly scales. Assimilation of satellite-based surface soil moisture observations into a land surface model is an effective way to estimate large-scale root zone soil moisture. The propagation of surface information into deeper soil layers depends on the model-specific representation of subsurface physics that is used in the assimilation system. In a suite of experiments we assimilate synthetic surface soil moisture observations into four different models (Catchment, Mosaic, Noah and CLM) using the Ensemble Kalman Filter. We demonstrate that identical twin experiments significantly overestimate the information that can be obtained from the assimilation of surface soil moisture observations. The second key result indicates that the potential of surface soil moisture assimilation to improve root zone information is higher when the surface to root zone coupling is stronger. Our experiments also suggest that (faced with unknown true subsurface physics) overestimating surface to root zone coupling in the assimilation system provides more robust skill improvements in the root zone compared with underestimating the coupling. When CLM is excluded from the analysis, the skill improvements from using models with different vertical coupling strengths are comparable for different subsurface truths. Finally, the skill improvements through assimilation were found to be sensitive to the regional climate and soil types.

  11. Variability in soil CO2 production and surface CO2 efflux across riparian-hillslope transitions

    Treesearch

    Vincent Jerald. Pacific

    2007-01-01

    The spatial and temporal controls on soil CO2 production and surface CO2 efflux have been identified as an outstanding gap in our understanding of carbon cycling. I investigated both the spatial and temporal variability of soil CO2 concentrations and surface CO2 efflux across eight topographically distinct riparian-hillslope transitions in the ~300 ha subalpine upper-...

  12. Improving satellite-based rainfall estimates over land using spaceborne surface soil moisture retrievals

    USDA-ARS?s Scientific Manuscript database

    Over land, remotely-sensed surface soil moisture and precipitation accumulation retrievals contain complementary information that can be exploited for the mutual benefit of both products. Here a Kalman filtering based tool is developed that utilizes a time series of spaceborne surface soil moisture ...

  13. Radar Measurement of Water Content Dynamics Over Bare and Vegetated Soil Surfaces

    NASA Astrophysics Data System (ADS)

    Serbin, G.; Or, D.

    2002-12-01

    Recent studies have shown substantial temperature dependence of microwave dielectric properties of soil-water mixtures, which could affect water content inferences from radar backscatter. Soil drying patterns were measured using ground-penetrating radar (GPR) with a 1 GHz center frequency horn antenna that was suspended (> 0.5 m) over bare and vegetated surfaces of soils with different textures. Soil water contents were derived from the surface reflection (SR) amplitudes and the propagation times (PT) to subsurface reflective interfaces. GPR-SR and -PT water content measurements over bare soil surfaces were in good agreement with gravimetric and time domain reflectometry (TDR) measured values. Measurements over vegetated surfaces showed gradual reductions in the maximal values of GPR-SR measured water contents with increase in plant canopy height. In contrast, the maximal value of GPR-PT-derived water content remained unchanged. Aboveground canopy reflections became more pronounced with canopy growth. GPR-SR data showed noticeable diurnal patterns in water contents of bare surfaces. Water content extreme values vary with soil type - for low surface area soils (sand), the maximum occurs at nighttime, whereas for high surface area soils (clay loam) the maximum occurs around midday at normal incidence. An increase in incidence angle caused a shift in measured maxima times to morning hours. These measurements highlight the need for improved understanding of physical effects on dynamics of near-surface radar measurements often used for hydrological studies.

  14. Role of Subsurface Physics in the Assimilation of Surface Soil Moisture Observations

    NASA Technical Reports Server (NTRS)

    Reichle, R. H.

    2010-01-01

    Root zone soil moisture controls the land-atmosphere exchange of water and energy and exhibits memory that may be useful for climate prediction at monthly scales. Assimilation of satellite-based surface soil moisture observations into a land surface model is an effective way to estimate large-scale root zone soil moisture. The propagation of surface information into deeper soil layers depends on the model-specific representation of subsurface physics that is used in the assimilation system. In a suite of experiments we assimilate synthetic surface soil moisture observations into four different models (Catchment, Mosaic, Noah and CLM) using the Ensemble Kalman Filter. We demonstrate that identical twin experiments significantly overestimate the information that can be obtained from the assimilation of surface soil moisture observations. The second key result indicates that the potential of surface soil moisture assimilation to improve root zone information is higher when the surface to root zone coupling is stronger. Our experiments also suggest that (faced with unknown true subsurface physics) overestimating surface to root zone coupling in the assimilation system provides more robust skill improvements in the root zone compared with underestimating the coupling. When CLM is excluded from the analysis, the skill improvements from using models with different vertical coupling strengths are comparable for different subsurface truths. Finally, the skill improvements through assimilation were found to be sensitive to the regional climate and soil types.

  15. Effects of soil surface roughness on interrill erosion processes and sediment particle size distribution

    USDA-ARS?s Scientific Manuscript database

    Soil surface roughness significantly impacts runoff and erosion under rainfall. Few previous studies on runoff generation focused on the effects of soil surface roughness on the sediment particle size distribution (PSD), which greatly affects interrill erosion and sedimentation processes. To address...

  16. Implementation of surface soil moisture data assimilation with watershed scale distributed hydrological model

    USDA-ARS?s Scientific Manuscript database

    This paper aims to investigate how surface soil moisture data assimilation affects each hydrologic process and how spatially varying inputs affect the potential capability of surface soil moisture assimilation at the watershed scale. The Ensemble Kalman Filter (EnKF) is coupled with a watershed scal...

  17. Transport of phenolic compounds from leaf surface of creosotebush and tarbush to soil surface by precipitation.

    PubMed

    Hyder, P W; Fredrickson, E L; Estell, R E; Lucero, M E

    2002-12-01

    During the last 100 years, many desert grasslands have been replaced by shrublands. One possible mechanism by which shrubs outcompete grasses is through the release of compounds that interfere with neighboring plants. Our objective was to examine the movement of secondary compounds from the leaf surface of creosotebush and tarbush to surrounding soil surfaces via precipitation. Units consisting of a funnel and bottle were used to collect stemflow, throughfall, and interspace precipitation samples from 20 creosotebush (two morphotypes) and 10 tarbush plants during three summer rainfall events in 1998. Precipitation samples were analyzed for total phenolics (both species) and nordihydroguaiaretic acid (creosotebush only). Phenolics were detected in throughfall and stemflow of both species with stemflow containing greater concentrations than throughfall (0.088 and 0.086 mg/ml for stemflow and 0.022 and 0.014 mg/ml for throughfall in creosotebush morphotypes U and V, respectively: 0.044 and 0.006 mg/ml for tarbush stemflow and throughfall, respectively). Nordihydroguaiaretic acid was not found in any precipitation collections. The results show that phenolic compounds produced by creosotebush and tarbush can be transported to the soil surface by precipitation, but whether concentrations are ecologically significant is uncertain. Nordihydroguaiaretic acid was not present in the runoff from creosotebush.

  18. Parameterization of albedo, thermal inertia, and surface roughness of desert scrub/sandy soil surface

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Mccumber, M.

    1986-01-01

    Spectral albedo, A sub n, for the direct solar beam is defined as A sub n (r sub i,s, theta sub 0) = r sub i exp(-s tan theta sub 0)1-I(s) where I(s) is the integral over all reflection angles describing the interception by the absorbing plants of the flux reflected from the soil, r sub i soil reflectance, assumed Lambertian, S the projection on a vertical plane of plants per unit surface area, and theta sub 0 is the solar zenith angle. Hemispheric reflectance for the direct solar beam equals 1-I(s) times the reflectance to the zenith. The values of s of 0.1, 0.2, and 0.3 respectively quantify sparse, moderately dense, and very dense desert scrub. Thin plants are assumed to be of negligible thermal inertia, and thus directly yield the absorbed insolation to the atmosphere. Surface thermal inertia is therefore effectively reduced. The ratio of surface roughness height to plant height is parameterized for sparse, moderately dense, and very dense desert-scrub as a function of s based on data expressing the dependence of this ratio on plant silhouette.

  19. Heterogeneity of soil surface temperature induced by xerophytic shrub in a revegetated desert ecosystem, northwestern China

    NASA Astrophysics Data System (ADS)

    Zhang, Ya-Feng; Wang, Xin-Ping; Pan, Yan-Xia; Hu, Rui; Zhang, Hao

    2013-06-01

    Variation characteristics of the soil surface temperature induced by shrub canopy greatly affects the near-surface biological and biochemical processes in desert ecosystems. However, information regarding the effects of shrub upon the heterogeneity of soil surface temperature is scarce. Here we aimed to characterize the effects of shrub ( Caragana korshinskii) canopy on the soil surface temperature heterogeneity at areas under shrub canopy and the neighbouring bare ground. Diurnal variations of soil surface temperature were measured at areas adjacent to the shrub base (ASB), beneath the midcanopy (BMC), and in the bare intershrub spaces (BIS) at the eastern, southern, western and northern aspects of shrub, respectively. Results indicated that diurnal mean soil surface temperature under the C. korshinskii canopy (ASB and BMC) was significantly lower than in the BIS, with the highest in the BIS, followed by the BMC and ASB. The diurnal maximum and diurnal variations of soil surface temperatures under canopy vary strongly with different aspects of shrub with the diurnal variation in solar altitude, which could be used as cues to detect safe sites for under-canopy biota. A significant empirical linear relationship was found between soil surface temperature and solar altitude, suggesting an empirical predicator that solar altitude can serve for soil surface temperature. Lower soil surface temperatures under the canopy than in the bare intershrub spaces imply that shrubs canopy play a role of `cool islands' in the daytime in terms of soil surface temperature during hot summer months in the desert ecosystems characterized by a mosaic of sparse vegetation and bare ground.

  20. Determination of Land Surface Temperature and Soil Moisture From Trmm/tmi Remote Sensing Data

    NASA Astrophysics Data System (ADS)

    Wen, J.; Su, Z.

    An analytical algorithm for determination of land surface temperature and soil mois- ture from Tropical Rainfall Measuring Mission/Microwave Imager (TRMM/TMI) re- mote sensing data is developed in this study. Error analyses illustrate that uncer- tainty of the involved parameters will not give serious errors in determination of land surface temperature and soil Fresnel reflectivity. With the proposed algorithm and TRMM/TMI remote sensing data collected during Global Energy and Water Experi- ment (GEWEX) Asian Monsoon Experiment in Tibet (GAME/Tibet) Intensive Obser- vation Period (IOP'98) field campaign in 1998, the regional and temporal distributions of the land surface temperature and volumetric soil moisture are estimated over the central Tibetan plateau area. To validate the proposed method, the ground measured surface temperature and soil volumetric moisture are compared to TRMM/TMI de- rived land surface temperature and soil Fresnel reflectivity respectively. The result shows that estimated surface temperature is in good agreement with ground mea- surements, their difference and correlation coefficient are 0.52+-2.41 K and 0.81. A quasi-linear relationship exists between the estimated Fresnel reflectivity and ground measured volumetric soil moisture with a correlation coefficient 0.82. The land sur- face characteristics can also be clearly identified from the regional distribution of the estimated land surface temperature, the mountainous area and water bodies give a very lower surface temperature while the river basin shows a higher surface temper- ature compared to the mountainous area. The southeastern part of the selected area has lower soil moisture, while the river basin exhibits high soil moisture values. It is therefore concluded that the proposed method is successful for the retrieval of land surface temperature and soil moisture using TRMM/TMI data. Keywords: TRMM/TMI, brightness temperature, land surface emperature, soil mois- ture and Tibetan

  1. Predicting root zone soil moisture with satellite near-surface moisture data in semiarid environments

    NASA Astrophysics Data System (ADS)

    Manfreda, S.; Baldwin, D. C.; Keller, K.; Smithwick, E. A. H.; Caylor, K. K.

    2015-12-01

    One of the most critical variables in semiarid environment is the soil water content that represents a controlling factor for both ecological and hydrological processes. Soil moisture monitoring over large scales may be extremely useful, but it is limited by the fact that most of the available tools provides only surface measurements not representative of the effective amount of water stored in the subsurface. Therefore, a methodology able to infer root-zone soil moisture starting from surface measurements is highly desirable. Recently a new simplified formulation has been introduced to provide a formal description of the mathematical relationship between surface measurements and root-zone soil moisture (Manfreda et al., HESS 2014). This is a physically based approach derived from the soil water balance equation, where different soil water loss functions have been explored in order to take into account for the non-linear processes governing soil water fluxes. The study highlighted that the soil loss function is the key for such relationship that is therefore strongly influenced by soil type and physiological plant types. The new formulation has been tested on soil moisture based on measurements taken from the African Monsoon Multidisciplinary Analysis (AMMA) and the Soil Climate Analysis Network (SCAN) databases. The method sheds lights on the physical controls for soil moisture dynamics and on the possibility to use such a simplified method for the description of root-zone soil moisture. Furthermore, the method has been also couple with an Enasamble Kalman Filter (EnKF) in order to optimize its performances for the large scale monitoring based the new satellite near-surface moisture data (SMAP). The optimized SMAR-EnKF model does well in both wet and dry climates and across many different soil types (51 SCAN locations) providing a strategy for real-time soil moisture monitoring.

  2. Circumpolar freeze/thaw surface status and surface soil moisture from Metop ASCAT

    NASA Astrophysics Data System (ADS)

    Bartsch, Annett; Paulik, Christoph; Melzer, Thomas; Hahn, Sebastian; Wagner, Wolfgang

    2013-04-01

    Circumpolar surface soil moisture and freeze/thaw surface status has been derived from Metop ASCAT within the framework of the ESA DUE Permafrost and STSE ALANIS-Methane projects. The dataset is available via Pangaea (doi:10.1594/PANGAEA.775959) and can be vizualized with the WebGIS of the DUE Permafrost data portal (www.ipf.tuwien.ac.at/permafrost). MetOp ASCAT data have been used for both the near surface soil moisture (SSM) product and determination of freeze/thaw status at panboreal/ arctic scale. Metop-A, launched in October 2006 by the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), is the first of three satellites within EUMETSAT's Polar System (EPS). The ASCAT SSM DUE Permafrost product is the result of an improved SSM retrieval algorithm developed at the Institute for Photogrammetry and Remote Sensing (IPF) of the Vienna University of Technology. The SSM Product is delivered with a weekly temporal resolution and 25 km spatial resolution. The soil moisture product also includes a quality flag which contains the number of used measurements. Data are masked for frozen ground conditions also based on MetOp ASCAT. The daily SSF is available as separate flag. The SSM product is provided as weekly averaged images north of 50°N in GeoTIFF/NetCDF format and EASE Grid projection Further, complementary regional scale (1km) freeze/thaw information is available at selected sites based on ENVISAT ASAR GM (PANGAEA http://doi.pangaea.de/10.1594/PANGAEA.779658).

  3. The SMAP Level 4 Surface and Root Zone Soil Moisture data assimilation product

    NASA Astrophysics Data System (ADS)

    Reichle, R. H.; De Lannoy, G. J. M.; Crow, W. T.; Kimball, J. S.; Koster, R. D.; Liu, Q.

    2014-12-01

    The NASA Soil Moisture Active Passive (SMAP) mission is scheduled for launch in January 2015 and will provide L-band radar and radiometer observations that are sensitive to surface soil moisture (in the top few centimeters of the soil column). For several of the key applications targeted by SMAP, however, knowledge of root zone soil moisture (defined here nominally as soil moisture in the top 1 m of the soil column) is needed. The SMAP mission will therefore provide a value-added Level 4 Surface and Root Zone Soil Moisture (L4_SM) product with the two key objectives: (i) to provide estimates of root zone soil moisture based on SMAP observations, and (ii) to provide a global surface and root zone soil moisture product that is spatially and temporally complete. The L4_SM algorithm uses an ensemble Kalman filter (EnKF) to merge SMAP observations with soil moisture estimates from the NASA GEOS-5 Catchment land surface model. The model describes the vertical transfer of soil moisture between the surface and root zone reservoirs and will be driven with observation-based surface meteorological forcing data, including precipitation, on a global 9 km Earth-fixed grid. The presentation provides an overview of the SMAP L4_SM algorithm and pre-launch validation. Specifically, an L4_SM prototype product based on the assimilation of observations from the Soil Moisture and Ocean Salinity (SMOS) mission was validated using in situ measurements from SMAP core validation sites (densely instrumented watersheds) and from more than 100 single-profile sensors scattered across the United States. The validation results indicate that the prototype soil moisture product satisfies the formal RMSE requirement for the L4_SM product of 0.04 m3/m3 (after removal of the long-term mean bias). An examination of the observation-minus-forecast residuals from the L4_SM system suggests where the system could be improved further.

  4. [Effects of soil crusts on surface hydrology in the semiarid Loess hilly area].

    PubMed

    Wei, Wei; Wen, Zhi; Chen, Li-Ding; Chen, Jin; Wu, Dong-Ping

    2012-11-01

    Soil crusts are distributed extensively in the Chinese Loess Plateau and play key roles in surface hydrological processes. In this study, a typical loess hilly region in Anjiagou catchment, Dingxi city, Gansu province was selected as the study region, and soil crusts in the catchment were investigated. Then, the hydrological effect of soil crusts was studied by using multi-sampling and hydrological monitoring experiments. Several key results were shown as follows. Firstly, compared with bared soil without crust cover, soil crusts can greatly reduce the bulk density, improve the porosity of soil, and raise the holding capacity of soil moisture which ranges from 1.4 to 1.9 times of that of bared soil. Secondly, the role of soil crust on rainfall interception was very significant. Moss crust was found to be strongest on rainfall interception, followed by synantectic crusts and lichen crusts. Bared soil without covering crusts was poorest in resisting rainfall splash. Thirdly, hydrological simulation experiments indicate that soil crusts play a certain positive role in promoting the water infiltration capacity, and the mean infiltration rate of the crusted soil was 2 times higher than that of the no-crust covered soils. While the accumulated infiltrated water amounts was also far higher than that of the bared soil.

  5. Directional reflectance factors for monitoring spatial changes in soil surface structure and soil organic matter erosion in agricultural systems

    NASA Astrophysics Data System (ADS)

    Croft, H.; Anderson, K.

    2012-04-01

    Soils can experience rapid structural degradation in response to land cover changes, resulting in reduced soil productivity, increased erodibility and a loss of soil organic matter (SOM). The breakdown of soil aggregates through slaking and raindrop impact is linked to organic matter turnover, with subsequently eroded material often displaying proportionally more SOM. A reduction in aggregate stability is reflected in a decline in soil surface roughness (SSR), indicating that a soil structural change can be used to highlight soil vulnerability to SOM loss through mineralisation or erosion. Accurate, spatially-continuous measurements of SSR are therefore needed at a variety of spatial and temporal scales to understand the spatial nature of SOM erosion and deposition. Remotely-sensed data can provide a cost-effective means of monitoring changes in soil surface condition over broad spatial extents. Previous work has demonstrated the ability of directional reflectance factors to monitor soil crusting within a controlled laboratory experiment, due to changes in the levels of self-shadowing effects by soil aggregates. However, further research is needed to test this approach in situ, where other soil variables may affect measured reflectance factors and to investigate the use of directional reflectance factors for monitoring soil erosion processes. This experiment assesses the potential of using directional reflectance factors to monitor changes in SSR, aggregate stability and soil organic carbon (SOC) content for two agricultural conditions. Five soil plots representing tilled and seedbed soils were subjected to different durations of natural rainfall, producing a range of different levels of SSR. Directional reflectance factors were measured concomitantly with sampling for soil structural and biochemical tests at each soil plot. Soil samples were taken to measure aggregate stability (wet sieving), SOC (loss on ignition) and soil moisture (gravimetric method). SSM

  6. Soil heat flux and day time surface energy balance closure at astronomical observatory, Thiruvananthapuram, south Kerala

    NASA Astrophysics Data System (ADS)

    Roxy, M. S.; Sumithranand, V. B.; Renuka, G.

    2014-06-01

    Soil heat flux is an important input component of surface energy balance. Estimates of soil heat flux were made in the year 2008 using soil temperature data at Astronomical Observatory, Thiruvananthapuram, south Kerala. Hourly values of soil heat flux from 00 to 24 LST are presented for selected days typical of the winter, pre-monsoon, SW monsoon and NE monsoon seasons. The diurnal variation is characterized by a cross-over from negative to positive values at 0700 h, occurrence of maximum around noon and return to negative values in the late evening. The energy storage term for the soil layer 0-0.05 m is calculated and the ground heat flux G ∗ is estimated in all seasons. Daytime surface energy balance at the surface on wet and dry seasons is investigated. The average Bowen's ratio during the wet and dry seasons were 0.541 and 0.515, respectively indicating that considerable evaporation takes place at the surface. The separate energy balance components were examined and the mean surface energy balance closure was found to be 0.742 and 0.795 for wet and dry seasons, respectively. When a new method that accounts for both soil thermal conduction and soil thermal convection was adopted to calculate the surface heat flux, the energy balance closure was found to be improved. Thus on the land surface under study, the soil vertical water movement is significant.

  7. Using SMOS brightness temperature and derived surface-soil moisture to characterize surface conditions and validate land surface models.

    NASA Astrophysics Data System (ADS)

    Polcher, Jan; Barella-Ortiz, Anaïs; Piles, Maria; Gelati, Emiliano; de Rosnay, Patricia

    2017-04-01

    The SMOS satellite, operated by ESA, observes the surface in the L-band. On continental surface these observations are sensitive to moisture and in particular surface-soil moisture (SSM). In this presentation we will explore how the observations of this satellite can be exploited over the Iberian Peninsula by comparing its results with two land surface models : ORCHIDEE and HTESSEL. Measured and modelled brightness temperatures show a good agreement in their temporal evolution, but their spatial structures are not consistent. An empirical orthogonal function analysis of the brightness temperature's error identifies a dominant structure over the south-west of the Iberian Peninsula which evolves during the year and is maximum in autumn and winter. Hypotheses concerning forcing-induced biases and assumptions made in the radiative transfer model are analysed to explain this inconsistency, but no candidate is found to be responsible for the weak spatial correlations. The analysis of spatial inconsistencies between modelled and measured TBs is important, as these can affect the estimation of geophysical variables and TB assimilation in operational models, as well as result in misleading validation studies. When comparing the surface-soil moisture of the models with the product derived operationally by ESA from SMOS observations similar results are found. The spatial correlation over the IP between SMOS and ORCHIDEE SSM estimates is poor (ρ 0.3). A single value decomposition (SVD) analysis of rainfall and SSM shows that the co-varying patterns of these variables are in reasonable agreement between both products. Moreover the first three SVD soil moisture patterns explain over 80% of the SSM variance simulated by the model while the explained fraction is only 52% of the remotely sensed values. These results suggest that the rainfall-driven soil moisture variability may not account for the poor spatial correlation between SMOS and ORCHIDEE products. Other reasons have to

  8. Improving hydrologic predictions of a catchment model via assimilation of surface soil moisture

    NASA Astrophysics Data System (ADS)

    Chen, Fan; Crow, Wade T.; Starks, Patrick J.; Moriasi, Daniel N.

    2011-04-01

    This paper examines the potential for improving Soil and Water Assessment Tool (SWAT) hydrologic predictions of root-zone soil moisture, evapotranspiration, and stream flow within the 341 km 2 Cobb Creek Watershed in southwestern Oklahoma through the assimilation of surface soil moisture observations using an Ensemble Kalman filter (EnKF). In a series of synthetic twin experiments assimilating surface soil moisture is shown to effectively update SWAT upper-layer soil moisture predictions and provide moderate improvement to lower layer soil moisture and evapotranspiration estimates. However, insufficient SWAT-predicted vertical coupling results in limited updating of deep soil moisture, regardless of the SWAT parameterization chosen for root-water extraction. Likewise, a real data assimilation experiment using ground-based soil moisture observations has only limited success in updating upper-layer soil moisture and is generally unsuccessful in enhancing SWAT stream flow predictions. Comparisons against ground-based observations suggest that SWAT significantly under-predicts the magnitude of vertical soil water coupling at the site, and this lack of coupling impedes the ability of the EnKF to effectively update deep soil moisture, groundwater flow and surface runoff. The failed attempt to improve stream flow prediction is also attributed to the inability of the EnKF to correct for existing biases in SWAT-predicted stream flow components.

  9. A radiosity-based model to compute the radiation transfer of soil surface

    NASA Astrophysics Data System (ADS)

    Zhao, Feng; Li, Yuguang

    2011-11-01

    A good understanding of interactions of electromagnetic radiation with soil surface is important for a further improvement of remote sensing methods. In this paper, a radiosity-based analytical model for soil Directional Reflectance Factor's (DRF) distributions was developed and evaluated. The model was specifically dedicated to the study of radiation transfer for the soil surface under tillage practices. The soil was abstracted as two dimensional U-shaped or V-shaped geometric structures with periodic macroscopic variations. The roughness of the simulated surfaces was expressed as a ratio of the height to the width for the U and V-shaped structures. The assumption was made that the shadowing of soil surface, simulated by U or V-shaped grooves, has a greater influence on the soil reflectance distribution than the scattering properties of basic soil particles of silt and clay. Another assumption was that the soil is a perfectly diffuse reflector at a microscopic level, which is a prerequisite for the application of the radiosity method. This radiosity-based analytical model was evaluated by a forward Monte Carlo ray-tracing model under the same structural scenes and identical spectral parameters. The statistics of these two models' BRF fitting results for several soil structures under the same conditions showed the good agreements. By using the model, the physical mechanism of the soil bidirectional reflectance pattern was revealed.

  10. Spatial differences in aeolian erosion of arid silty- sand soils due to surface features

    NASA Astrophysics Data System (ADS)

    Edri, Avi; Katra, Itzhak; Avraham, Dody

    2014-05-01

    The significance of soil erosion by wind is substantial by means of soil degradation and air pollution. There is still a gap in quantifying the aeolian soil erosion in response to changes in surface features. The aim of this study is to quantify the aeolian erosion of silty-sand soil in an arid region (Yamin Plateau, Negev, Israel) under different wind and surface conditions. The study was conducted in experimental plots of sparse vegetation (SV), rock fragment (RF), and mechanical crust (MC) under natural and disturbed soil surfaces. Aeolian simulations were executed through the use of a portable wind tunnel with different wind speeds. Variables measured during the simulations include wind profile and shear stress, horizontal sand flux (saltation), vertical flux of total aeolian sediments (TAS), and concentration of PM10 (particle less than 10 micrometers in diameter). The results show that during experiments at 6 and 11 m/s in natural soil surface, the cumulative PM10 concentration (mg/m3) in plot MC was 5 and 6.8 times higher than in plots RF and SV, respectively. Soil loss calculation for PM10 at these wind speed in natural surface shows that the soil at plot MC was the most available for erosion with a loss of 253 and 1530 mg/m2 (7 minutes), respectively. This is 2 and 6 times higher than in plots SV and RF, respectively. The impact of soil surface disturbance was more significant in plot MC under wind speed of 6 m/s and in plot RF under wind speed of 11 m/s. Soil loss calculation for sand (> 100 µm) at speed of 6 m/s in natural surface shows that the loss at plot MC was 2 and 5.8 times higher than in plots RF and SV, respectively. The results indicate on spatial differences in the aeolian erosion of silty - sand soil in response to changes in wind speed and surface characteristics.

  11. Bacteria increase arid-land soil surface temperature through the production of sunscreens

    PubMed Central

    Couradeau, Estelle; Karaoz, Ulas; Lim, Hsiao Chien; Nunes da Rocha, Ulisses; Northen, Trent; Brodie, Eoin; Garcia-Pichel, Ferran

    2016-01-01

    Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming has apparent and immediate consequences for the soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. These results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales. PMID:26785770

  12. Bacteria increase arid-land soil surface temperature through the production of sunscreens

    SciTech Connect

    Couradeau, Estelle; Karaoz, Ulas; Lim, Hsiao Chien; Nunes da Rocha, Ulisses; Northen, Trent; Brodie, Eoin; Garcia-Pichel, Ferran

    2016-01-20

    Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming has apparent and immediate consequences for the soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. In conclusion, these results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales.

  13. Bacteria increase arid-land soil surface temperature through the production of sunscreens.

    PubMed

    Couradeau, Estelle; Karaoz, Ulas; Lim, Hsiao Chien; Nunes da Rocha, Ulisses; Northen, Trent; Brodie, Eoin; Garcia-Pichel, Ferran

    2016-01-20

    Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming has apparent and immediate consequences for the soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. These results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales.

  14. Using IKONOS Imagery to Estimate Surface Soil Property Variability in Two Alabama Physiographies

    NASA Technical Reports Server (NTRS)

    Sullivan, Dana; Shaw, Joey; Rickman, Doug

    2005-01-01

    Knowledge of surface soil properties is used to assess past erosion and predict erodibility, determine nutrient requirements, and assess surface texture for soil survey applications. This study was designed to evaluate high resolution IKONOS multispectral data as a soil- mapping tool. Imagery was acquired over conventionally tilled fields in the Coastal Plain and Tennessee Valley physiographic regions of Alabama. Acquisitions were designed to assess the impact of surface crusting, roughness and tillage on our ability to depict soil property variability. Soils consisted mostly of fine-loamy, kaolinitic, thermic Plinthic Kandiudults at the Coastal Plain site and fine, kaolinitic, thermic Rhodic Paleudults at the Tennessee Valley site. Soils were sampled in 0.20 ha grids to a depth of 15 cm and analyzed for % sand (0.05 - 2 mm), silt (0.002 -0.05 mm), clay (less than 0.002 mm), citrate dithionite extractable iron (Fe(sub d)) and soil organic carbon (SOC). Four methods of evaluating variability in soil attributes were evaluated: 1) kriging of soil attributes, 2) co-kriging with soil attributes and reflectance data, 3) multivariate regression based on the relationship between reflectance and soil properties, and 4) fuzzy c-means clustering of reflectance data. Results indicate that co-kriging with remotely sensed data improved field scale estimates of surface SOC and clay content compared to kriging and regression methods. Fuzzy c-means worked best using RS data acquired over freshly tilled fields, reducing soil property variability within soil zones compared to field scale soil property variability.

  15. Temporal Dynamics of Soil Moisture Variability at the Landscape Scale: Implications for Land Surface Models.

    NASA Astrophysics Data System (ADS)

    Montaldo, N.; Albertson, J. D.

    2001-12-01

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends directly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, microbial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances affect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a conservation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spatial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calculate land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions using the proposed soil moisture

  16. Temporal Dynamics of Soil Moisture Variability: Implications For Land Surface Models

    NASA Astrophysics Data System (ADS)

    Montaldo, N.; Albertson, J. D.

    Meteorological and hydrological forecasting models share soil moisture as a critical boundary condition. Partitioning of received energy at the land surface depends di- rectly on this variable, as does the partitioning of rainfall into its possible routes over and through the soil. In Land Surface Models (LSMs) the temporal dynamic of soil moisture spatial variability is a fundamental issue in large-scale flux predictions. From remote sensing observations soil moisture values are averaged in the horizontal over rather large regions (pixels). The averaging areas will be getting even larger as we move from aircraft mounted sensors to satellite mounting. These data are to be used ultimately to estimate spatial averages of other processes that depend on soil moisture, such as, runoff generation, drainage, evaporation, sensible heat fluxes, crop yield, mi- crobial activity, etc. Consequently, the LSMs have to predict spatial averaged flux over large region from average values of the soil moisture. But soil moisture variances af- fect flux predictions, which depend nonlinearly on soil moisture, because many of the other processes possess distinct threshold aspects to their nonlinear dependence on soil moisture. Through application of well-developed Reynolds averaging rules from fluid mechanics to the equation of Richards and Darcy-Buckingham, we write a con- servation equation for the horizontal variance of soil moisture. And, through closure arguments, we are able to describe the individual terms that produce and destroy spa- tial variance through time in terms of the mean soil moisture state and other observable system properties such as vegetation and soil properties variability. Finally, we calcu- late land surface fluxes from second order Taylor expansion, using our soil moisture variance closure model, and the other observable system properties. In this work, we demonstrate significant improvements in land surface large-scale flux predictions us- ing the proposed

  17. Using IKONOS Imagery to Estimate Surface Soil Property Variability in Two Alabama Physiographies

    NASA Technical Reports Server (NTRS)

    Sullivan, Dana; Shaw, Joey; Rickman, Doug

    2005-01-01

    Knowledge of surface soil properties is used to assess past erosion and predict erodibility, determine nutrient requirements, and assess surface texture for soil survey applications. This study was designed to evaluate high resolution IKONOS multispectral data as a soil- mapping tool. Imagery was acquired over conventionally tilled fields in the Coastal Plain and Tennessee Valley physiographic regions of Alabama. Acquisitions were designed to assess the impact of surface crusting, roughness and tillage on our ability to depict soil property variability. Soils consisted mostly of fine-loamy, kaolinitic, thermic Plinthic Kandiudults at the Coastal Plain site and fine, kaolinitic, thermic Rhodic Paleudults at the Tennessee Valley site. Soils were sampled in 0.20 ha grids to a depth of 15 cm and analyzed for % sand (0.05 - 2 mm), silt (0.002 -0.05 mm), clay (less than 0.002 mm), citrate dithionite extractable iron (Fe(sub d)) and soil organic carbon (SOC). Four methods of evaluating variability in soil attributes were evaluated: 1) kriging of soil attributes, 2) co-kriging with soil attributes and reflectance data, 3) multivariate regression based on the relationship between reflectance and soil properties, and 4) fuzzy c-means clustering of reflectance data. Results indicate that co-kriging with remotely sensed data improved field scale estimates of surface SOC and clay content compared to kriging and regression methods. Fuzzy c-means worked best using RS data acquired over freshly tilled fields, reducing soil property variability within soil zones compared to field scale soil property variability.

  18. Retrieval and Mapping of Soil Texture Based on Land Surface Diurnal Temperature Range Data from MODIS

    PubMed Central

    Wang, De-Cai; Zhang, Gan-Lin; Zhao, Ming-Song; Pan, Xian-Zhang; Zhao, Yu-Guo; Li, De-Cheng; Macmillan, Bob

    2015-01-01

    Numerous studies have investigated the direct retrieval of soil properties, including soil texture, using remotely sensed images. However, few have considered how soil properties influence dynamic changes in remote images or how soil processes affect the characteristics of the spectrum. This study investigated a new method for mapping regional soil texture based on the hypothesis that the rate of change of land surface temperature is related to soil texture, given the assumption of similar starting soil moisture conditions. The study area was a typical flat area in the Yangtze-Huai River Plain, East China. We used the widely available land surface temperature product of MODIS as the main data source. We analyzed the relationships between the content of different particle soil size fractions at the soil surface and land surface day temperature, night temperature and diurnal temperature range (DTR) during three selected time periods. These periods occurred after rainfalls and between the previous harvest and the subsequent autumn sowing in 2004, 2007 and 2008. Then, linear regression models were developed between the land surface DTR and sand (> 0.05 mm), clay (< 0.001 mm) and physical clay (< 0.01 mm) contents. The models for each day were used to estimate soil texture. The spatial distribution of soil texture from the studied area was mapped based on the model with the minimum RMSE. A validation dataset produced error estimates for the predicted maps of sand, clay and physical clay, expressed as RMSE of 10.69%, 4.57%, and 12.99%, respectively. The absolute error of the predictions is largely influenced by variations in land cover. Additionally, the maps produced by the models illustrate the natural spatial continuity of soil texture. This study demonstrates the potential for digitally mapping regional soil texture variations in flat areas using readily available MODIS data. PMID:26090852

  19. Retrieval and Mapping of Soil Texture Based on Land Surface Diurnal Temperature Range Data from MODIS.

    PubMed

    Wang, De-Cai; Zhang, Gan-Lin; Zhao, Ming-Song; Pan, Xian-Zhang; Zhao, Yu-Guo; Li, De-Cheng; Macmillan, Bob

    2015-01-01

    Numerous studies have investigated the direct retrieval of soil properties, including soil texture, using remotely sensed images. However, few have considered how soil properties influence dynamic changes in remote images or how soil processes affect the characteristics of the spectrum. This study investigated a new method for mapping regional soil texture based on the hypothesis that the rate of change of land surface temperature is related to soil texture, given the assumption of similar starting soil moisture conditions. The study area was a typical flat area in the Yangtze-Huai River Plain, East China. We used the widely available land surface temperature product of MODIS as the main data source. We analyzed the relationships between the content of different particle soil size fractions at the soil surface and land surface day temperature, night temperature and diurnal temperature range (DTR) during three selected time periods. These periods occurred after rainfalls and between the previous harvest and the subsequent autumn sowing in 2004, 2007 and 2008. Then, linear regression models were developed between the land surface DTR and sand (> 0.05 mm), clay (< 0.001 mm) and physical clay (< 0.01 mm) contents. The models for each day were used to estimate soil texture. The spatial distribution of soil texture from the studied area was mapped based on the model with the minimum RMSE. A validation dataset produced error estimates for the predicted maps of sand, clay and physical clay, expressed as RMSE of 10.69%, 4.57%, and 12.99%, respectively. The absolute error of the predictions is largely influenced by variations in land cover. Additionally, the maps produced by the models illustrate the natural spatial continuity of soil texture. This study demonstrates the potential for digitally mapping regional soil texture variations in flat areas using readily available MODIS data.

  20. Element concentrations in surface soils of the Coconino Plateau, Grand Canyon region, Coconino County, Arizona

    USGS Publications Warehouse

    Van Gosen, Bradley S.

    2016-09-15

    This report provides the geochemical analyses of a large set of background soils collected from the surface of the Coconino Plateau in northern Arizona. More than 700 soil samples were collected at 46 widespread areas, sampled from sites that appear unaffected by mineralization and (or) anthropogenic contamination. The soils were analyzed for 47 elements, thereby providing data on metal concentrations in soils representative of the plateau. These background concentrations can be used, for instance, for comparison to metal concentrations found in soils potentially affected by natural and anthropogenic influences on the Coconino Plateau in the Grand Canyon region of Arizona.The soil sampling survey revealed low concentrations for the metals most commonly of environmental concern, such as arsenic, cobalt, chromium, copper, mercury, manganese, molybdenum, lead, uranium, vanadium, and zinc. For example, the median concentrations of the metals in soils of the Coconino Plateau were found to be comparable to the mean values previously reported for soils of the western United States.

  1. Ectomycorrhizal Influence on Particle Size, Surface Structure, Mineral Crystallinity, Functional Groups, and Elemental Composition of Soil Colloids from Different Soil Origins

    PubMed Central

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O–H stretching and bending, C–H stretching, C=O stretching, etc.) by 3–26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40–300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12–35% decreases in most functional groups, 15–55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C : O, C : N, and C : Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil. PMID:23766704

  2. Ectomycorrhizal influence on particle size, surface structure, mineral crystallinity, functional groups, and elemental composition of soil colloids from different soil origins.

    PubMed

    Li, Yanhong; Wang, Huimei; Wang, Wenjie; Yang, Lei; Zu, Yuangang

    2013-01-01

    Limited data are available on the ectomycorrhizae-induced changes in surface structure and composition of soil colloids, the most active portion in soil matrix, although such data may benefit the understanding of mycorrhizal-aided soil improvements. By using ectomycorrhizae (Gomphidius viscidus) and soil colloids from dark brown forest soil (a good loam) and saline-alkali soil (heavily degraded soil), we tried to approach the changes here. For the good loam either from the surface or deep soils, the fungus treatment induced physical absorption of covering materials on colloid surface with nonsignificant increases in soil particle size (P > 0.05). These increased the amount of variable functional groups (O-H stretching and bending, C-H stretching, C=O stretching, etc.) by 3-26% and the crystallinity of variable soil minerals (kaolinite, hydromica, and quartz) by 40-300%. However, the fungus treatment of saline-alkali soil obviously differed from the dark brown forest soil. There were 12-35% decreases in most functional groups, 15-55% decreases in crystallinity of most soil minerals but general increases in their grain size, and significant increases in soil particle size (P < 0.05). These different responses sharply decreased element ratios (C:O, C:N, and C:Si) in soil colloids from saline-alkali soil, moving them close to those of the good loam of dark brown forest soil.

  3. A comparison of techniques used to estimate the amount of resuspended soil on plant surfaces.

    PubMed

    Hinton, T G; Kopp, P; Ibrahim, S; Bubryak, I; Syomov, A; Tobler, L; Bell, C

    1995-04-01

    The objectives of this study were to compare four common techniques used to estimate soil mass loadings on plant surfaces and to assess the need to account for particle-size distributions of both the soil tracer and contaminant of concern within the soil. Soil loadings (g soil kg-1 dried plant) from split samples collected in a pasture near Chernobyl were estimated using soil tracers of plutonium analyzed via alpha spectroscopy (mean +/- standard error; 1.0 +/- 0.2), titanium analyzed with an inductive coupled plasma spectrometer; (3.6 +/- 0.6), and neutron activation analysis for scandium (8.1 +/- 1.6), as well as simply washing the soil off the vegetation (34.1 +/- 5.6) Differences were significant at p < 0.001. We also found that soil loading estimates from any one technique varied by a factor of 10 depending on the soil particle size used in the calculations. This was because soil loadings decreased when smaller-sized soil fractions dominated the resuspension process. However, the percent of the plant's total contamination attributable to soil loading increased with smaller soil particles. Smaller soil particles apparently contribute less to the mass of soil loading (g soil kg-1 dry plant), but more to the total plant contamination (Bq) because of the higher concentration of contaminant found in the smaller-sized soil fractions. Differences in mass loading estimates due to the technique chosen (a factor of 10), or due to differences in elemental concentration as a result of the soil particle size used in the calculation (also a factor of 10), were greater than the natural variability observed in the field (2.5).

  4. A comparison of techniques used to estimate the amount of resuspended soil on plant surfaces

    SciTech Connect

    Hinton, T.G. |; Kopp, P.; Tobler, L.

    1995-04-01

    The objectives of this study were to compare four common techniques used to estimate soil mass loadings on plant surfaces and to assess the need to account for particle-size distributions of both the soil tracer and contaminant of concern within the soil. Soil loadings (g soil kg{sup -1} dried plant) from split samples collected in a pasture near Chernobyl were estimated using soil tracers of plutonium analyzed via alpha spectroscopy (mean {plus_minus} standard error; 1.0 {plus_minus} 0.2), titanium analyzed with an inductive coupled plasma spectrometer; (3.6 {plus_minus} 0.6), and neutron activation analysis for scandium (8.1 {plus_minus} 1.6), as well as simply washing the soil off the vegetation (34.1 {plus_minus} 5.6). Differences were significant at p<0.001. We also found that soil loading estimates from any one technique varied by a factor of 10 depending on the soil particle size used in the calculations. This was because soil loadings decreased m hen smaller-sized soil fractions dominated the resuspension process. However, the percent of the plant`s total contamination attributable to soil loading increased with smaller soil particles. Smaller soil particles apparently contribute less to the mass of soil loading (g soil kg{sup -1} dry plant), but more to the total plant contamination (Bq) because of the higher concentration of contaminant found in the smaller-sized soil fractions. Differences in mass loading estimates due to the technique chosen (a factor of 10), or due to differences in elemental concentration as a result of the soil particle size used in the calculation (also a factor of 10), were greater than the natural variability observed in the field (2.5).

  5. A multi-frequency measurement of thermal microwave emission from soils: The effects of soil texture and surface roughness

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Oneill, P. E.; Jackson, T. J.; Engman, E. T. (Principal Investigator)

    1981-01-01

    An experiment on remote sensing of soil moisture content was conducted over bare fields with microwave radiometers at the frequencies of 1.4 GHz, 5 GHz, and 10.7 GHz during July - September of 1981. Three bare fields with different surface roughnesses and soil textures were prepared for the experiment. Ground truth acquisition of soil temperatures and moisture contents for 5 layers down to the depths of 15 cm was made concurrently with radiometric measurements. The experimental results show that the effect of surface roughness is to increase the soils' brightness temperature and to reduce the slope of regression between brightness temperature and moisture content. The slopes of regression for soils with different textures are found to be comparable, and the effect of soil texture is reflected in the difference of regression line intercepts at brightness temperature axis. The result is consistent with laboratory measurement of soils' dielectric permittivity. Measurements on wet smooth bare fields give lower brightness temperatures at 5 GHz than at 1.4 GHz.

  6. Effects of meteorological models on the solution of the surface energy balance and soil temperature variations in bare soils

    NASA Astrophysics Data System (ADS)

    Saito, Hirotaka; Šimůnek, Jiri

    2009-07-01

    SummaryA complete evaluation of the soil thermal regime can be obtained by evaluating the movement of liquid water, water vapor, and thermal energy in the subsurface. Such an evaluation requires the simultaneous solution of the system of equations for the surface water and energy balance, and subsurface heat transport and water flow. When only daily climatic data is available, one needs not only to estimate diurnal cycles of climatic data, but to calculate the continuous values of various components in the energy balance equation, using different parameterization methods. The objective of this study is to quantify the impact of the choice of different estimation and parameterization methods, referred together to as meteorological models in this paper, on soil temperature predictions in bare soils. A variety of widely accepted meteorological models were tested on the dataset collected at a proposed low-level radioactive-waste disposal site in the Chihuahua Desert in West Texas. As the soil surface was kept bare during the study, no vegetation effects were evaluated. A coupled liquid water, water vapor, and heat transport model, implemented in the HYDRUS-1D program, was used to simulate diurnal and seasonal soil temperature changes in the engineered cover installed at the site. The modified version of HYDRUS provides a flexible means for using various types of information and different models to evaluate surface mass and energy balance. Different meteorological models were compared in terms of their prediction errors for soil temperatures at seven observation depths. The results obtained indicate that although many available meteorological models can be used to solve the energy balance equation at the soil-atmosphere interface in coupled water, vapor, and heat transport models, their impact on overall simulation results varies. For example, using daily average climatic data led to greater prediction errors, while relatively simple meteorological models may

  7. Density and stability of soil organic carbon beneath impervious surfaces in urban areas.

    PubMed

    Wei, Zongqiang; Wu, Shaohua; Yan, Xiao; Zhou, Shenglu

    2014-01-01

    Installation of impervious surfaces in urban areas has attracted increasing attention due to its potential hazard to urban ecosystems. Urban soils are suggested to have robust carbon (C) sequestration capacity; however, the C stocks and dynamics in the soils covered by impervious surfaces that dominate urban areas are still not well characterized. We compared soil organic C (SOC) densities and their stabilities under impervious surface, determined by a 28-d incubation experiment, with those in open areas in Yixing City, China. The SOC density (0-20 cm) under impervious surfaces was, on average, 68% lower than that in open areas. Furthermore, there was a significantly (P<0.05) positive correlation between the densities of SOC and total nitrogen (N) in the open soils, whereas the correlation was not apparent for the impervious-covered soils, suggesting that the artificial soil sealing in urban areas decoupled the cycle of C and N. Cumulative CO2-C evolved during the 28-d incubation was lower from the impervious-covered soils than from the open soils, and agreed well with a first-order decay model (Ct = C1+C0(1-e-kt)). The model results indicated that the SOC underlying capped surfaces had weaker decomposability and lower turnover rate. Our results confirm the unique character of urban SOC, especially that beneath impervious surface, and suggest that scientific and management views on regional SOC assessment may need to consider the role of urban carbon stocks.

  8. Development of a surface scanning soil analysis instrument.

    PubMed

    Falahat, S; Köble, T; Schumann, O; Waring, C; Watt, G

    2012-07-01

    ANSTO is developing a nuclear field instrument for measurement of soil composition; particularly carbon. The instrument utilises the neutron activation approach with clear advantages over existing soil sampling and laboratory analysis. A field portable compact pulsed neutron generator and γ-ray detector are used for PGNAA and INS techniques simultaneously. Many elements can be quantified from a homogenised soil volume equivalent to the top soil layers. Results from first test experiments and current developments are reported. Copyright © 2011 Elsevier Ltd. All rights reserved.

  9. Biochar amendment to the soil surface reduces fumigant emissions and enhances soil microorganism recovery

    USDA-ARS?s Scientific Manuscript database

    During soil fumigation, it is ideal to mitigate soil fumigant emissions, ensure pest control efficacy, and speed up the recovery of the soil microorganism population established post-application. However, there is currently no fumigant emission reduction strategy that can meet all the above requirem...

  10. Soil surface protection by Biocrusts: effects of functional groups on textural properties

    NASA Astrophysics Data System (ADS)

    Concostrina-Zubiri, Laura; Huber-Sannwald, Elisabeth; Martínez, Isabel; Flores Flores, José Luis; Escudero, Adrián

    2015-04-01

    In drylands, where vegetation cover is commonly scarce, soil surface is prone to wind and water soil erosion, with the subsequent loss of topsoil structure and chemical properties. These processes are even more pronounced in ecosystems subjected to extra erosive forces, such as grasslands and rangelands that support livestock production. However, some of the physiological and functional traits of biocrusts (i.e., complex association of cyanobacteria, lichens, mosses, fungi and soil particles) make them ideal to resist in disturbed environments and at the same time to protect soil surface from mechanical perturbations. In particular, the filaments and exudates of soil cyanobacteria and the rhizines of lichen can bind together soil particles, forming soil aggregates at the soil surface and thus enhancing soil stability. Also, they act as "biological covers" that preserve the most vulnerable soil layer from wind and runoff erosion and raindrop impact, maintaining soil structure and composition. In this work, we evaluated soil textural properties and organic matter content under different functional groups of biocrusts (i.e., cyanobacteria crust, 3 lichen species, 1 moss species) and in bare soil. In order to assess the impact of livestock trampling on soil properties and on Biocrust function, we sampled three sites conforming a disturbance gradient (low, medium and high impact sites) and a long-term livestock exclusion as control site. We found that the presence of biocrusts had little effects on soil textural properties and organic matter content in the control site, while noticeable differences were found between bare soil and soil under biocrusts (e.g., up to 16-37% higher clay content, compared to bare soil and up to 10% higher organic matter content). In addition, we found that depending on morphological traits and grazing regime, the effects of biocrusts changed along the gradient. For example, soil under the lichen Diploschistes diacapsis, with thick thallus

  11. Homogenization of the soil surface following fire in semiarid grasslands

    Treesearch

    Carleton S. White

    2011-01-01

    Semiarid grasslands accumulate soil beneath plant "islands" that are raised above bare interspaces. This fine-scale variation in microtopographic relief is plant-induced and is increased with shrub establishment. Research found that fire-induced water repellency enhanced local-scale soil erosion that reduced variation in microtopographic relief, suggesting...

  12. Enhancing agricultural forecasting using SMOS surface soil moisture retrievals

    USDA-ARS?s Scientific Manuscript database

    With the onset of data availability from the ESA Soil Moisture and Ocean Salinity (SMOS) mission (Kerr and Levine, 2008) and the expected 2015 launch of the NASA Soil Moisture Active and Passive (SMAP) mission (Entekhabi et al., 2010), the next five years should see a significant expansion in our ab...

  13. Spectral reflectance of surface soils - A statistical analysis

    NASA Technical Reports Server (NTRS)

    Crouse, K. R.; Henninger, D. L.; Thompson, D. R.

    1983-01-01

    The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.

  14. Spectral reflectance of surface soils - A statistical analysis

    NASA Technical Reports Server (NTRS)

    Crouse, K. R.; Henninger, D. L.; Thompson, D. R.

    1983-01-01

    The relationship of the physical and chemical properties of soils to their spectral reflectance as measured at six wavebands of Thematic Mapper (TM) aboard NASA's Landsat-4 satellite was examined. The results of performing regressions of over 20 soil properties on the six TM bands indicated that organic matter, water, clay, cation exchange capacity, and calcium were the properties most readily predicted from TM data. The middle infrared bands, bands 5 and 7, were the best bands for predicting soil properties, and the near infrared band, band 4, was nearly as good. Clustering 234 soil samples on the TM bands and characterizing the clusters on the basis of soil properties revealed several clear relationships between properties and reflectance. Discriminant analysis found organic matter, fine sand, base saturation, sand, extractable acidity, and water to be significant in discriminating among clusters.

  15. Corn Stover Impacts on Near-Surface Soil Properties of No-Till Corn In Ohio

    SciTech Connect

    Blanco-Canqui, H; Lal, Rattan; Post, W M.; Izaurralde, R Cesar C.; Owens, L B.

    2006-01-06

    Corn stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2 emissions. Excessive stover removal may, however, negatively impact near-surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density, and water content over a 1-yr period following a systematic removal or addition of stover from three no-till soils under corn in Ohio.

  16. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs

    PubMed Central

    Edmondson, J. L.; Stott, I.; Davies, Z. G.; Gaston, K. J.; Leake, J. R.

    2016-01-01

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health. PMID:27641002

  17. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs.

    PubMed

    Edmondson, J L; Stott, I; Davies, Z G; Gaston, K J; Leake, J R

    2016-09-19

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health.

  18. Soil surface temperatures reveal moderation of the urban heat island effect by trees and shrubs

    NASA Astrophysics Data System (ADS)

    Edmondson, J. L.; Stott, I.; Davies, Z. G.; Gaston, K. J.; Leake, J. R.

    2016-09-01

    Urban areas are major contributors to air pollution and climate change, causing impacts on human health that are amplified by the microclimatological effects of buildings and grey infrastructure through the urban heat island (UHI) effect. Urban greenspaces may be important in reducing surface temperature extremes, but their effects have not been investigated at a city-wide scale. Across a mid-sized UK city we buried temperature loggers at the surface of greenspace soils at 100 sites, stratified by proximity to city centre, vegetation cover and land-use. Mean daily soil surface temperature over 11 months increased by 0.6 °C over the 5 km from the city outskirts to the centre. Trees and shrubs in non-domestic greenspace reduced mean maximum daily soil surface temperatures in the summer by 5.7 °C compared to herbaceous vegetation, but tended to maintain slightly higher temperatures in winter. Trees in domestic gardens, which tend to be smaller, were less effective at reducing summer soil surface temperatures. Our findings reveal that the UHI effects soil temperatures at a city-wide scale, and that in their moderating urban soil surface temperature extremes, trees and shrubs may help to reduce the adverse impacts of urbanization on microclimate, soil processes and human health.

  19. Dual frequency microwave radiometer measurements of soil moisture for bare and vegetated rough surfaces

    NASA Technical Reports Server (NTRS)

    Lee, S. L.

    1974-01-01

    Controlled ground-based passive microwave radiometric measurements on soil moisture were conducted to determine the effects of terrain surface roughness and vegetation on microwave emission. Theoretical predictions were compared with the experimental results and with some recent airborne radiometric measurements. The relationship of soil moisture to the permittivity for the soil was obtained in the laboratory. A dual frequency radiometer, 1.41356 GHz and 10.69 GHz, took measurements at angles between 0 and 50 degrees from an altitude of about fifty feet. Distinct surface roughnesses were studied. With the roughness undisturbed, oats were later planted and vegetated and bare field measurements were compared. The 1.4 GHz radiometer was less affected than the 10.6 GHz radiometer, which under vegetated conditions was incapable of detecting soil moisture. The bare surface theoretical model was inadequate, although the vegetation model appeared to be valid. Moisture parameters to correlate apparent temperature with soil moisture were compared.

  20. A New Model of Size-graded Soil Veneer on the Lunar Surface

    NASA Technical Reports Server (NTRS)

    Basu, Abhijit; McKay, David S.

    2005-01-01

    Introduction. We propose a new model of distribution of submillimeter sized lunar soil grains on the lunar surface. We propose that in the uppermost millimeter or two of the lunar surface, soil-grains are size graded with the finest nanoscale dust on top and larger micron-scale particles below. This standard state is perturbed by ejecta deposition of larger grains at the lunar surface, which have a coating of dusty layer that may not have substrates of intermediate sizes. Distribution of solar wind elements (SWE), agglutinates, vapor deposited nanophase Fe0 in size fractions of lunar soils and ir spectra of size fractions of lunar soils are compatible with this model. A direct test of this model requires bringing back glue-impregnated tubes of lunar soil samples to be dissected and examined on Earth.

  1. Using Remote Sensing Data to Evaluate Surface Soil Properties in Alabama Ultisols

    NASA Technical Reports Server (NTRS)

    Sullivan, Dana G.; Shaw, Joey N.; Rickman, Doug; Mask, Paul L.; Luvall, Jeff

    2005-01-01

    Evaluation of surface soil properties via remote sensing could facilitate soil survey mapping, erosion prediction and allocation of agrochemicals for precision management. The objective of this study was to evaluate the relationship between soil spectral signature and surface soil properties in conventionally managed row crop systems. High-resolution RS data were acquired over bare fields in the Coastal Plain, Appalachian Plateau, and Ridge and Valley provinces of Alabama using the Airborne Terrestrial Applications Sensor multispectral scanner. Soils ranged from sandy Kandiudults to fine textured Rhodudults. Surface soil samples (0-1 cm) were collected from 163 sampling points for soil organic carbon, particle size distribution, and citrate dithionite extractable iron content. Surface roughness, soil water content, and crusting were also measured during sampling. Two methods of analysis were evaluated: 1) multiple linear regression using common spectral band ratios, and 2) partial least squares regression. Our data show that thermal infrared spectra are highly, linearly related to soil organic carbon, sand and clay content. Soil organic carbon content was the most difficult to quantify in these highly weathered systems, where soil organic carbon was generally less than 1.2%. Estimates of sand and clay content were best using partial least squares regression at the Valley site, explaining 42-59% of the variability. In the Coastal Plain, sandy surfaces prone to crusting limited estimates of sand and clay content via partial least squares and regression with common band ratios. Estimates of iron oxide content were a function of mineralogy and best accomplished using specific band ratios, with regression explaining 36-65% of the variability at the Valley and Coastal Plain sites, respectively.

  2. Using Remote Sensing Data to Evaluate Surface Soil Properties in Alabama Ultisols

    NASA Technical Reports Server (NTRS)

    Sullivan, Dana G.; Shaw, Joey N.; Rickman, Doug; Mask, Paul L.; Luvall, Jeff

    2005-01-01

    Evaluation of surface soil properties via remote sensing could facilitate soil survey mapping, erosion prediction and allocation of agrochemicals for precision management. The objective of this study was to evaluate the relationship between soil spectral signature and surface soil properties in conventionally managed row crop systems. High-resolution RS data were acquired over bare fields in the Coastal Plain, Appalachian Plateau, and Ridge and Valley provinces of Alabama using the Airborne Terrestrial Applications Sensor multispectral scanner. Soils ranged from sandy Kandiudults to fine textured Rhodudults. Surface soil samples (0-1 cm) were collected from 163 sampling points for soil organic carbon, particle size distribution, and citrate dithionite extractable iron content. Surface roughness, soil water content, and crusting were also measured during sampling. Two methods of analysis were evaluated: 1) multiple linear regression using common spectral band ratios, and 2) partial least squares regression. Our data show that thermal infrared spectra are highly, linearly related to soil organic carbon, sand and clay content. Soil organic carbon content was the most difficult to quantify in these highly weathered systems, where soil organic carbon was generally less than 1.2%. Estimates of sand and clay content were best using partial least squares regression at the Valley site, explaining 42-59% of the variability. In the Coastal Plain, sandy surfaces prone to crusting limited estimates of sand and clay content via partial least squares and regression with common band ratios. Estimates of iron oxide content were a function of mineralogy and best accomplished using specific band ratios, with regression explaining 36-65% of the variability at the Valley and Coastal Plain sites, respectively.

  3. Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation.

    PubMed

    Odukkathil, Greeshma; Vasudevan, Namasivayam

    2016-01-01

    The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides.

  4. Feasibility of using a seismic surface wave method to study seasonal and weather effects on shallow surface soils

    USDA-ARS?s Scientific Manuscript database

    The objective of the paper is to study the temporal variations of the subsurface soil properties due to seasonal and weather effects using a combination of a new seismic surface method and an existing acoustic probe system. A laser Doppler vibrometer (LDV) based multi-channel analysis of surface wav...

  5. Application of manure to no-till soils: Phosphorus losses by sub-surface and surface pathways

    USDA-ARS?s Scientific Manuscript database

    Concern over the acceleration of eutrophication by agricultural runoff has focused attention on manure management in no-till. We evaluated losses of phosphorus (P) in sub-surface and surface flow as a function of dairy manure application to no-till soils on a dairy farm in north-central Pennsylvania...

  6. Shallow groundwater effect on land surface temperature and surface energy balance under bare soil conditions: modeling and description

    USDA-ARS?s Scientific Manuscript database

    Appreciating when and how groundwater affects surface temperature and energy fluxes is important for utilizing remote sensing in groundwater studies and for integrating aquifers within land surface models. To explore the shallow groundwater effect, we numerically exposed two soil profiles – one havi...

  7. Synergism of active and passive microwave data for estimating bare surface soil moisture

    NASA Technical Reports Server (NTRS)

    Saatchi, Sasan S.; Njoku, Eni G.; Wegmueller, Urs

    1993-01-01

    Active and passive microwave sensors were applied effectively to the problem of estimating the surface soil moisture in a variety of environmental conditions. Research to date has shown that both types of sensors are also sensitive to the surface roughness and the vegetation cover. In estimating the soil moisture, the effect of the vegetation and roughness are often corrected either by acquiring multi-configuration (frequency and polarization) data or by adjusting the surface parameters in order to match the model predictions to the measured data. Due to the limitations on multi-configuration spaceborne data and the lack of a priori knowledge of the surface characteristics for parameter adjustments, it was suggested that the synergistic use of the sensors may improve the estimation of the soil moisture over the extreme range of naturally occurring soil and vegetation conditions. To investigate this problem, the backscattering and emission from a bare soil surface using the classical rough surface scattering theory were modeled. The model combines the small perturbation and the Kirchhoff approximations in conjunction with the Peak formulation to cover a wide range of surface roughness parameters with respect to frequency for both active and passive measurements. In this approach, the same analytical method was used to calculate the backscattering and emissivity. Therefore, the active and passive simulations can be combined at various polarizations and frequencies in order to estimate the soil moisture more actively. As a result, it is shown that (1) the emissivity is less dependent on the surface correlation length, (2) the ratio of the backscattering coefficient (HH) over the surface reflectivity (H) is almost independent of the soil moisture for a wide range of surface roughness, and (3) this ratio can be approximated as a linear function of the surface rms height. The results were compared with the data obtained by a multi-frequency radiometer

  8. Multiscale analysis of surface soil moisture dynamics in a mesoscale catchment utilizing an integrated ecohydrological model

    NASA Astrophysics Data System (ADS)

    Korres, W.; Reichenau, T. G.; Schneider, K.

    2012-12-01

    Soil moisture is one of the fundamental variables in hydrology, meteorology and agriculture, influencing the partitioning of solar energy into latent and sensible heat flux as well as the partitioning of precipitation into runoff and percolation. Numerous studies have shown that in addition to natural factors (rainfall, soil, topography etc.) agricultural management is one of the key drivers for spatio-temporal patterns of soil moisture in agricultural landscapes. Interactions between plant growth, soil hydrology and soil nitrogen transformation processes are modeled by using a dynamically coupled modeling approach. The process-based ecohydrological model components of the integrated decision support system DANUBIA are used to identify the important processes and feedbacks determining soil moisture patterns in agroecosystems. Integrative validation of plant growth and surface soil moisture dynamics serves as a basis for a spatially distributed modeling analysis of surface soil moisture patterns in the northern part of the Rur catchment (1100 sq km), Western Germany. An extensive three year dataset (2007-2009) of surface soil moisture-, plant- (LAI, organ specific biomass and N) and soil- (texture, N, C) measurements was collected. Plant measurements were carried out biweekly for winter wheat, maize, and sugar beet during the growing season. Soil moisture was measured with three FDR soil moisture stations. Meteorological data was measured with an eddy flux station. The results of the model validation showed a very good agreement between the modeled plant parameters (biomass, green LAI) and the measured parameters with values between 0.84 and 0.98 (Willmotts index of agreement). The modeled surface soil moisture (0 - 20 cm) showed also a very favorable agreement with the measurements for winter wheat and sugar beet with an RMSE between 1.68 and 3.45 Vol.-%. For maize, the RMSE was less favorable particularly in the 1.5 months prior to harvest. The modeled soil

  9. Soil carbon sequestration by three perennial legume pastures is greater in deeper soil layers than in the surface soil

    NASA Astrophysics Data System (ADS)

    Guan, X.-K.; Turner, N. C.; Song, L.; Gu, Y.-J.; Wang, T.-C.; Li, F.-M.

    2016-01-01

    Soil organic carbon (SOC) plays a vital role as both a sink for and source of atmospheric carbon. Revegetation of degraded arable land in China is expected to increase soil carbon sequestration, but the role of perennial legumes on soil carbon stocks in semiarid areas has not been quantified. In this study, we assessed the effect of alfalfa (Medicago sativa L.) and two locally adapted forage legumes, bush clover (Lespedeza davurica S.) and milk vetch (Astragalus adsurgens Pall.) on the SOC concentration and SOC stock accumulated annually over a 2 m soil profile. The results showed that the concentration of SOC in the bare soil decreased slightly over the 7 years, while 7 years of legume growth substantially increased the concentration of SOC over the 0-2.0 m soil depth. Over the 7-year growth period the SOC stocks increased by 24.1, 19.9 and 14.6 Mg C ha-1 under the alfalfa, bush clover and milk vetch stands, respectively, and decreased by 4.2 Mg C ha-1 in the bare soil. The sequestration of SOC in the 1-2 m depth of the soil accounted for 79, 68 and 74 % of the SOC sequestered in the 2 m deep soil profile under alfalfa, bush clover and milk vetch, respectively. Conversion of arable land to perennial legume pasture resulted in a significant increase in SOC, particularly at soil depths below 1 m.

  10. Organic matter composition of soil macropore surfaces under different agricultural management practices

    NASA Astrophysics Data System (ADS)

    Glæsner, Nadia; Leue, Marin; Magid, Jacob; Gerke, Horst H.

    2016-04-01

    Understanding the heterogeneous nature of soil, i.e. properties and processes occurring specifically at local scales is essential for best managing our soil resources for agricultural production. Examination of intact soil structures in order to obtain an increased understanding of how soil systems operate from small to large scale represents a large gap within soil science research. Dissolved chemicals, nutrients and particles are transported through the disturbed plow layer of agricultural soil, where after flow through the lower soil layers occur by preferential flow via macropores. Rapid movement of water through macropores limit the contact between the preferentially moving water and the surrounding soil matrix, therefore contact and exchange of solutes in the water is largely restricted to the surface area of the macropores. Organomineral complex coated surfaces control sorption and exchange properties of solutes, as well as availability of essential nutrients to plant roots and to the preferentially flowing water. DRIFT (Diffuse Reflectance infrared Fourier Transform) Mapping has been developed to examine composition of organic matter coated macropores. In this study macropore surfaces structures will be determined for organic matter composition using DRIFT from a long-term field experiment on waste application to agricultural soil (CRUCIAL, close to Copenhagen, Denmark). Parcels with 5 treatments; accelerated household waste, accelerated sewage sludge, accelerated cattle manure, NPK and unfertilized, will be examined in order to study whether agricultural management have an impact on the organic matter composition of intact structures.

  11. Distribution of 137Cs in surface soil of Fraser's Hill, Pahang, Malaysia

    NASA Astrophysics Data System (ADS)

    Bakar, Ahmad Sanadi Abu; Hamzah, Zaini; Saat, Ahmad

    2017-01-01

    Caesium-137 (137Cs) in an anthropogenic radionuclide originated from the fission of fissile materials. Nuclear weapons testing during the 1960s and the Chernobyl disaster introduced substantial amount of 137Cs into the atmosphere that are then eventually deposited back to earth's surface. Caesium-137 can be used as tracer to study soil movements since it adsorbs to soil particles. This paper aims to describe the distribution of 137Cs in surface soil of Fraser's Hill, Pahang, determine the levels of 137Cs here compared to other areas, and to check correlation of 137Cs levels to physical data. A series of sampling were carried out between February 2014 and August 2015. Soil samples were taken from 31 locations using soil scraper. The samples were then taken to the laboratory to be dried, homogenized, grinded and sieved. The activity concentration of 137Cs in the samples was determined using gamma spectroscopy. The activity concentration was found to be between 0.26 Bq/kg and 5.14 Bq/kg. Although this paper only studies surface soil, 137Cs is expected to be present within the soil body. Further study of 137Cs in the soil body can be used to predictive model for soil erosion.

  12. Land surface phenologies viewed in the middle infrared: seasonal contrasts between vegetation, soils, and impervious surfaces

    NASA Astrophysics Data System (ADS)

    Henebry, G. M.; Krehbiel, C.; Kovalskyy, V.

    2012-12-01

    The middle infrared (MIR) region of the electromagnetic spectrum spans 3-5 microns. It is the mixing zone between reflected sunlight and emitted earthlight in roughly equal proportions. This region has received very little attention in terrestrial remote sensing. Yet the MIR merits exploration of how it could be used for monitoring land surface phenologies (LSP) and seasonalities due to five characteristics. First, green vegetation is MIR-dark, reflecting just 2-5% of the incident radiation. Second, soils are MIR-bright, reflecting up to one-third of the incident radiation. Third, impervious surfaces, such as concretes, asphalts, and other building and paving materials are also MIR-bright. Fourth, the resulting seasonal contrast in MIR between vegetated and non-vegetated surfaces lets urbanized areas emerge from the vegetated landscape. Fifth, MIR wavelengths penetrate anthropogenic haze and smoke because the particle radii are smaller. Here we use MODIS (MYD02) image time series to illustrate the temporal progressions of MIR at various wavelengths and how they compare to and diverge from the more familiar NDVI and derived LSP metrics.IR portrait of the USA east of W98: maximum value composite of Aqua MODIS MIR band 23 during DOY 219-233 of 2010.

  13. Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment

    EPA Science Inventory

    Predicting the spatial distribution of soil moisture is an important hydrological question. We measured the spatial distribution of surface soil moisture (upper 6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2 m) and small catchment scale (0.84 ha) in...

  14. Parametric exponentially correlated surface emission model for L-band passive microwave soil moisture retrieval

    USDA-ARS?s Scientific Manuscript database

    Surface soil moisture is an important parameter in hydrology and climate investigations. Current and future satellite missions with L-band passive microwave radiometers can provide valuable information for monitoring the global soil moisture. A factor that can play a significant role in the modeling...

  15. Spatial Distribution of Surface Soil Moisture in a Small Forested Catchment

    EPA Science Inventory

    Predicting the spatial distribution of soil moisture is an important hydrological question. We measured the spatial distribution of surface soil moisture (upper 6 cm) using an Amplitude Domain Reflectometry sensor at the plot scale (2 × 2 m) and small catchment scale (0.84 ha) in...

  16. Corn stover harvest and tillage impacts on near-surface soil physical quality

    USDA-ARS?s Scientific Manuscript database

    Excessive harvest of corn (Zea mays L.) stover for ethanol production has raised concerns regarding negative consequences on soil physical quality. Our objective was to quantify the impact of two tillage practices and three levels of corn stover harvest on near-surface soil physical quality through ...

  17. Role of subsurface physics in the assimilation of surface soil moisture observations

    USDA-ARS?s Scientific Manuscript database

    Soil moisture controls the exchange of water and energy between the land surface and the atmosphere and exhibits memory that may be useful for climate prediction at monthly time scales. Though spatially distributed observations of soil moisture are increasingly becoming available from remotely sense...

  18. SORPTION OF 2,3,7,8-TETRACHLORODIBENZO-P-DIOXIN FROM WATER BY SURFACE SOILS

    EPA Science Inventory

    The sorption of l4C-labeled 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) from water by two uncontaminated surface soils from the Times Beach, MO, area was evalu- ated by using batch shake testing. Sorption isotherm plots for the soil with the lower fraction organic carbon (f,) wer...

  19. Sub-surface soil carbon changes affects biofuel greenhouse gas emissions

    USDA-ARS?s Scientific Manuscript database

    Changes in direct soil organic carbon (SOC) can have a major impact on overall greenhouse gas (GHG) emissions from biofuels when using life-cycle assessment (LCA). Estimated changes in SOC, when accounted for in an LCA, are typically derived from near-surface soil depths (<30 cm). Changes in subsurf...

  20. Groundwater control of mangrove surface elevation: shrink and swell varies with soil depth

    USGS Publications Warehouse

    Whelan, K.R.T.; Smith, T. J.; Cahoon, D.R.; Lynch, J.C.; Anderson, G.H.

    2005-01-01

    We measured monthly soil surface elevation change and determined its relationship to groundwater changes at a mangrove forest site along Shark River, Everglades National Park, Florida. We combined the use of an original design, surface elevation table with new rod-surface elevation tables to separately track changes in the mid zone (0?4 m), the shallow root zone (0?0.35 m), and the full sediment profile (0?6 m) in response to site hydrology (daily river stage and groundwater piezometric pressure). We calculated expansion and contraction for each of the four constituent soil zones (surface [accretion and erosion; above 0 m], shallow zone [0?0.35 m], middle zone [0.35?4 m], and bottom zone [4?6 m]) that comprise the entire soil column. Changes in groundwater pressure correlated strongly with changes in soil elevation for the entire profile (Adjusted R2 5 0.90); this relationship was not proportional to the depth of the soil profile sampled. The change in thickness of the bottom soil zone accounted for the majority (R2 5 0.63) of the entire soil profile expansion and contraction. The influence of hydrology on specific soil zones and absolute elevation change must be considered when evaluating the effect of disturbances, sea level rise, and water management decisions on coastal wetland systems.

  1. Wavelength Identification and Diffuse Reflectance Estimation for Surface and Profile Soil Properties

    USDA-ARS?s Scientific Manuscript database

    Optical diffuse reflectance spectroscopy (DRS) has been used to estimate soil physical and chemical properties, but much of the previous work has been limited to surface soils or to samples obtained from a restricted geographic area. Our objectives in this research were (1) to assess the accuracy of...

  2. Improving hydrologic predictions of a catchment model via assimilation of surface soil moisture

    USDA-ARS?s Scientific Manuscript database

    This paper examines the potential for improving Soil and Water Assessment Tool (SWAT) hydrologic predictions within the 341 km2 Cobb Creek Watershed in southwestern Oklahoma through the assimilation of surface soil moisture observations using an Ensemble Kalman filter (EnKF). In a series of synthet...

  3. Apollo program soil mechanics experiment. [interaction of the lunar module with the lunar surface

    NASA Technical Reports Server (NTRS)

    Scott, R. F.

    1975-01-01

    The soil mechanics investigation was conducted to obtain information relating to the landing interaction of the lunar module (LM) with the lunar surface, and lunar soil erosion caused by the spacecraft engine exhaust. Results obtained by study of LM landing performance on each Apollo mission are summarized.

  4. Comparison of models for determining soil-surface carbon dioxide effluxes in different agricultural systems

    USDA-ARS?s Scientific Manuscript database

    Soil-surface CO2 efflux (SCE) models are appealing due to expense and labor of fine temporal- and spatial-resolution field measurements. However, several simple SCE models are reported in the literature. Our objective was to compare and validate selected soil temperature (Ts)- and water content ('v)...

  5. Portable wind tunnels for field testing of soils and natural surfaces

    USDA-ARS?s Scientific Manuscript database

    Large stationary wind tunnels have been used to test the erodibility of soils and to study in detail the processes controlling erosion rates. These tunnels require the use of disturbed soil samples which may result in parameter estimations that are not consistent with the natural surface. Several ...

  6. Cropping sequence and nitrogen fertilization impact on surface residue, soil carbon sequestration, and crop yields

    USDA-ARS?s Scientific Manuscript database

    Information is needed on the effect of management practices on soil C storage for obtaining C credit. The effects of tillage, cropping sequence, and N fertilization were evaluated on dryland crop and surface residue C and soil organic C (SOC) at the 0-120 cm depth in a Williams loam from 2006 to 201...

  7. Soil heat flux calculation for sunlit and shaded surfaces under row crops: 2. Model Test

    USDA-ARS?s Scientific Manuscript database

    A method to calculate surface soil heat flux (G0) as a function of net radiation to the soil (RN,S) was developed that accounts for positional variability across a row crop interrow. The method divides the interrow into separate sections, which may be shaded, partially sunlit, or fully sunlit, and c...

  8. Effect of Vegetation Patterns on SAR derived Surface Soil Moisture Distribution

    NASA Astrophysics Data System (ADS)

    Koyama, C. N.; Schneider, K.

    2012-12-01

    Soil moisture can be regarded as one of the important life sustaining entities on our planet. Among its various functions, the first is probably to enable the growth of vegetation on the land surface. Apart from this, water stored in soils plays many other important roles in the global water (and energy) cycle. In the past decades, radar imaging has proven its potential to quantitatively estimate the near surface water content of soils at high spatial resolutions. The use of active microwave data to measure surface soil moisture requires the consideration of several factors like e.g. soil texture, surface roughness, and vegetation. Among these factors, the presence of a vegetation cover is perhaps the major impediment to accurate quantitative retrievals of soil moisture. On the one hand, the vegetation has a disturbing effect on the radar reflectivity and thus causes errors in the soil moisture retrieval which is generally based on theoretical or experimental relationships between the dielectric properties of the soil surface and the radar backscattering coefficient. On the other hand, the spatial distribution of vegetation with e.g. different crop types with different transpiration coefficients and different phenological development, etc, can cause large variations in the plant water consumption and thus has a significant impact on the soil moisture patterns. We have developed methods to estimate the amount of biomass for different crop types and the underlying surface soil water content directly from polarimetric L-band SAR images. While the horizontally-transmit horizontally-receive co-polarization (hh) is most sensitive towards the dielectric soil properties, the horizontally-transmit vertically-receive cross-polarization (hv) is much more sensitive towards the backscattering from the vegetation canopy. In addition the polarimetric observables entropy (H), alpha angle (α), and the total reflected power (span), all of which are highly affected by the canopy

  9. [Optimization of application parameters of soil seed bank in vegetation recovery via response surface methodology].

    PubMed

    He, Meng-Xuan; Li, Hong-Yuan; Mo, Xun-Qiang; Meng, Wei-Qing; Yang, Jia-Nan

    2014-08-01

    The thickness of surface soil, the covering thickness and the number of adding arbor seeds are all important factors to be considered in the application of soil seed bank (SSB) for vegetation recovery. To determine the optimal conditions, the Box-Behnken central composite design with three parameters and three levels was conducted and Design-Expert was used for response surface optimization. Finally, the optimal model and optimal level of each parameter were selected. The quadratic model was more suitable for response surface optimization (P < 0.0001), indicating the model had good statistical significance which could express ideal relations between all the independent variable and dependent variable. For the optimum condition, the thickness of surface soil was 4.3 cm, the covering thickness was 2 cm, and the number of adding arbor seeds was 224 ind x m(-2), under which the number of germinated seedlings could be reached up to 6222 plants x m(-2). During the process of seed germination, significant interactions between the thickness of surface soil and the covering thickness, as well as the thickness of surface soil and the number of adding arbor seeds were found, but the relationship between the covering thickness and the number of adding arbor seeds was relatively unremarkable. Among all the parameters, the thickness of surface soil was the most important one, which had the steepest curve and the largest standardized coefficient.

  10. An EKF assimilation of AMSR-E soil moisture into the ISBA land surface scheme

    NASA Astrophysics Data System (ADS)

    Draper, C. S.; Mahfouf, J.-F.; Walker, J. P.

    2009-10-01

    An Extended Kalman Filter (EKF) for the assimilation of remotely sensed near-surface soil moisture into the Interactions between Surface, Biosphere, and Atmosphere (ISBA) model is described. ISBA is the land surface scheme in Météo-France's Aire Limitée Adaptation Dynamique développement InterNational (ALADIN) Numerical Weather Prediction (NWP) model, and this work is directed toward providing initial conditions for NWP. The EKF is used to assimilate near-surface soil moisture observations retrieved from C-band Advanced Microwave Scanning Radiometer (AMSR-E) brightness temperatures into ISBA. The EKF can translate near-surface soil moisture observations into useful increments to the root-zone soil moisture. If the observation and model soil moisture errors are equal, the Kalman gain for the root-zone soil moisture is typically 20-30%, resulting in a mean net monthly increment for July 2006 of 0.025 m3 m-3 over ALADIN's European domain. To test the benefit of evolving the background error, the EKF is compared to a Simplified EKF (SEKF), in which the background errors at the time of the analysis are constant. While the Kalman gains for the EKF and SEKF are derived from different model processes, they produce similar soil moisture analyses. Despite this similarity, the EKF is recommended for future work where the extra computational expense can be afforded. The method used to rescale the near-surface soil moisture data to the model climatology has a greater influence on the analysis than the error covariance evolution approach, highlighting the importance of developing appropriate methods for rescaling remotely sensed near-surface soil moisture data.

  11. Predicting root zone soil moisture with soil properties and satellite near-surface moisture data across the conterminous United States

    NASA Astrophysics Data System (ADS)

    Baldwin, D.; Manfreda, S.; Keller, K.; Smithwick, E. A. H.

    2017-03-01

    Satellite-based near-surface (0-2 cm) soil moisture estimates have global coverage, but do not capture variations of soil moisture in the root zone (up to 100 cm depth) and may be biased with respect to ground-based soil moisture measurements. Here, we present an ensemble Kalman filter (EnKF) hydrologic data assimilation system that predicts bias in satellite soil moisture data to support the physically based Soil Moisture Analytical Relationship (SMAR) infiltration model, which estimates root zone soil moisture with satellite soil moisture data. The SMAR-EnKF model estimates a regional-scale bias parameter using available in situ data. The regional bias parameter is added to satellite soil moisture retrievals before their use in the SMAR model, and the bias parameter is updated continuously over time with the EnKF algorithm. In this study, the SMAR-EnKF assimilates in situ soil moisture at 43 Soil Climate Analysis Network (SCAN) monitoring locations across the conterminous U.S. Multivariate regression models are developed to estimate SMAR parameters using soil physical properties and the moderate resolution imaging spectroradiometer (MODIS) evapotranspiration data product as covariates. SMAR-EnKF root zone soil moisture predictions are in relatively close agreement with in situ observations when using optimal model parameters, with root mean square errors averaging 0.051 [cm3 cm-3] (standard error, s.e. = 0.005). The average root mean square error associated with a 20-fold cross-validation analysis with permuted SMAR parameter regression models increases moderately (0.082 [cm3 cm-3], s.e. = 0.004). The expected regional-scale satellite correction bias is negative in four out of six ecoregions studied (mean = -0.12 [-], s.e. = 0.002), excluding the Great Plains and Eastern Temperate Forests (0.053 [-], s.e. = 0.001). With its capability of estimating regional-scale satellite bias, the SMAR-EnKF system can predict root zone soil moisture over broad extents and has

  12. Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

    NASA Technical Reports Server (NTRS)

    Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

    2000-01-01

    This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

  13. Modeling diffusive Cd and Zn contaminant emissions from soils to surface waters.

    PubMed

    Bonten, Luc T C; Kroes, Joop G; Groenendijk, Piet; van der Grift, Bas

    2012-09-01

    Modeling contaminant transport of diffusive contaminants is generally difficult, as most contaminants are located in the top soil where soil properties will vary strongly with depth and often a strong gradient in contaminant concentrations exists. When groundwater periodically penetrates the contaminated layers, stationary models (like most 3D models) cannot adequately describe contaminant transport. Therefore we have combined a hydrological instationary model using a 1D distributed column approach with a simple geochemical model to describe contaminant transport in the soil. Special to this model is that it includes lateral drainage from the soil column to different types of surface waters, which makes it possible to calculate surface water emissions especially for fluctuating groundwater tables. To test this model approach, we used it to quantify surface water emissions from soils in a catchment in the Kempen area which has been diffusively contaminated with Cd and Zn by zinc smelters. We ran the model for the period 1880-2000, starting with an uncontaminated soil in 1880. The model could describe both water discharge, surface water concentrations and current soil contents of Cd and Zn well. Further the model calculations showed that a stationary approach would underestimate leaching to surface waters considerably. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Uncertainties of seasonal surface climate predictions induced by soil moisture biases in the La Plata Basin

    NASA Astrophysics Data System (ADS)

    Sorensson, Anna; Berbery, E. Hugo

    2015-04-01

    This work examines the evolution of soil moisture initialization biases and their effects on seasonal forecasts depending on the season and vegetation type for a regional model over the La Plata Basin in South America. WRF/Noah model simulations covering multiple cases during a two-year period are designed to emphasize the conceptual nature of the simulations at the expense of statistical significance of the results. Analysis of the surface climate shows that the seasonal predictive skill is higher when the model is initialized during the wet season and the initial soil moisture differences are small. Large soil moisture biases introduce large surface temperature biases, particularly for Savanna, Grassland and Cropland vegetation covers at any time of the year, thus introducing uncertainty in the surface climate. Regions with Evergreen Broadleaf Forest have roots that extend to the deep layer whose moisture content affects the surface temperature through changes in the partitioning of the surface fluxes. The uncertainties of monthly maximum temperature can reach several degrees during the dry season in cases when: (a) the soil is much wetter in the reanalysis than in the WRF/Noah equilibrium soil moisture, and (b) the memory of the initial value is long due to scarce rainfall and low temperatures. This study suggests that responses of the atmosphere to soil moisture initialization depend on how the initial wet and dry conditions are defined, stressing the need to take into account the characteristics of a particular region and season when defining soil moisture initialization experiments.

  15. Sensitivity of a model projection of near-surface permafrost degradation to soil column depth and representation of soil organic matter.

    Treesearch

    David M. Lawrence; Andrew G. Slater; Vladimir E. Romanovsky; Dmitry J. Nicolsky

    2008-01-01

    The sensitivity of a global land-surface model projection of near-surface permafrost degradation is assessed with respect to explicit accounting of the thermal and hydrologic properties of soil organic matter and to a deepening of the soil column from 3.5 to 50 or more m. Together these modifications result in substantial improvements in the simulation of near-surface...

  16. Land surface model calibration through microwave data assimilation for improving soil moisture simulations

    NASA Astrophysics Data System (ADS)

    Yang, Kun; Zhu, La; Chen, Yingying; Zhao, Long; Qin, Jun; Lu, Hui; Tang, Wenjun; Han, Menglei; Ding, Baohong; Fang, Nan

    2016-02-01

    Soil moisture is a key variable in climate system, and its accurate simulation needs effective soil parameter values. Conventional approaches may obtain soil parameter values at point scale, but they are costly and not efficient at grid scale (10-100 km) of current climate models. This study explores the possibility to estimate soil parameter values by assimilating AMSR-E (Advanced Microwave Scanning Radiometer for Earth Observing System) brightness temperature (TB) data. In the assimilation system, the TB is simulated by the coupled system of a land surface model (LSM) and a radiative transfer model (RTM), and the simulation errors highly depend on parameters in both the LSM and the RTM. Thus, sensitive soil parameters may be inversely estimated through minimizing the TB errors. A crucial step for the parameter estimation is made to suppress the contamination of uncertainties in atmospheric forcing data. The effectiveness of the estimated parameter values is evaluated against intensive measurements of soil parameters and soil moisture in three grasslands of the Tibetan Plateau and the Mongolian Plateau. The results indicate that this satellite data-based approach can improve the data quality of soil porosity, a key parameter for soil moisture modeling, and LSM simulations with the estimated parameter values reasonably reproduce the measured soil moisture. This demonstrates it is feasible to calibrate LSMs for soil moisture simulations at grid scale by assimilating microwave satellite data, although more efforts are expected to improve the robustness of the model calibration.

  17. [Effects of P application on P concentrations in paddy soil and its surface water: a simulation test].

    PubMed

    Zhou, Quanlai; Zhao, Muqiu; Lu, Caiyan; Shi, Yi; Chen, Xin

    2006-10-01

    An anaerobic incubation test was conducted to study the effects of different P application rate on the P concentrations in paddy soil and its surface water. The results showed that soil available P (Olsen-P) decreased rapidly at the beginning, but approached to stable after 60 days of P application. Both Olsen-P and residual P increased with increasing P application rate, and Olsen-P had a positive correlation with P application rate, suggesting that the test soil had a strong P adsorption capacity. After P application, the total P (TP) in soil surface water increased rapidly, and then decreased slowly, showing that there was a P exchange between soil and its surface water. After 120 days of P application, there was an exponential relationship between soil surface water TP and P application. The TP in soil surface water increased rapidly when the P application rate was 400 - 800 kg x hm (-2) , and easy to be lost when the P application rate was higher than 800 kg x hm(-2). The simulation with split line model on the relationship between soil Olsen-P and soil surface water TP showed that the change point of soil Olsen-P, which induced a sharp increase of soil surface water TP concentration, was 82. 7 mg x kg( -l) , corresponding to a P application rate being about 712 x kg hm(-2). Soil Olsen-P could be a good indicator in forecasting the P loss from soil surface water.

  18. A Monte Carlo reflectance model for soil surfaces with three-dimensional structure

    NASA Technical Reports Server (NTRS)

    Cooper, K. D.; Smith, J. A.

    1985-01-01

    A Monte Carlo soil reflectance model has been developed to study the effect of macroscopic surface irregularities larger than the wavelength of incident flux. The model treats incoherent multiple scattering from Lambertian facets distributed on a periodic surface. Resulting bidirectional reflectance distribution functions are non-Lambertian and compare well with experimental trends reported in the literature. Examples showing the coupling of the Monte Carlo soil model to an adding bidirectional canopy of reflectance model are also given.

  19. Computer Implementation of the Bounding Surface Plasticity Model for Cohesive Soils.

    DTIC Science & Technology

    1983-12-01

    80 M R478, October 1980. 6. Dafalias, Y.F., and L.R. Herrmann, "A Generalized Bounding Surface Constitutive Model for Clays", Proceedings of the... Model for Isotropic Cohesive Soils and its Application at the Grenoble Workshop", Genoble Workshop on Constitutive Relations for Soils, -Sept. 6-8...Dafalias, Y.F., "Bounding Surface Elastoplasticity - Viscoplasticity for Particulate Cohesive Media", IUTAM Symposium on Deformation and Failure of

  20. Mapping Soil Surface Macropores Using Infrared Thermography: An Exploratory Laboratory Study

    PubMed Central

    de Lima, João L. M. P.; Abrantes, João R. C. B.; Silva, Valdemir P.; de Lima, M. Isabel P.; Montenegro, Abelardo A. A.

    2014-01-01

    Macropores and water flow in soils and substrates are complex and are related to topics like preferential flow, nonequilibrium flow, and dual-continuum. Hence, the quantification of the number of macropores and the determination of their geometry are expected to provide a better understanding on the effects of pores on the soil's physical and hydraulic properties. This exploratory study aimed at evaluating the potential of using infrared thermography for mapping macroporosity at the soil surface and estimating the number and size of such macropores. The presented technique was applied to a small scale study (laboratory soil flume). PMID:25371915

  1. The Impact of Microwave-Derived Surface Soil Moisture on Watershed Hydrological Modeling

    NASA Technical Reports Server (NTRS)

    ONeill, P. E.; Hsu, A. Y.; Jackson, T. J.; Wood, E. F.; Zion, M.

    1997-01-01

    The usefulness of incorporating microwave-derived soil moisture information in a semi-distributed hydrological model was demonstrated for the Washita '92 experiment in the Little Washita River watershed in Oklahoma. Initializing the hydrological model with surface soil moisture fields from the ESTAR airborne L-band microwave radiometer on a single wet day at the start of the study period produced more accurate model predictions of soil moisture than a standard hydrological initialization with streamflow data over an eight-day soil moisture drydown.

  2. Soil carbon sequestration by three perennial legume pastures is greater in deeper soil layers than in the surface soil

    NASA Astrophysics Data System (ADS)

    Guan, X.-K.; Turner, N. C.; Song, L.; Gu, Y.-J.; Wang, T.-C.; Li, F.-M.

    2015-07-01

    Soil organic carbon (SOC) plays a vital role as both a sink for and source of atmospheric carbon. Revegetation of degraded arable land in China is expected to increase soil carbon sequestration, but the role of perennial legumes on soil carbon stocks in semiarid areas has not been quantified. In this study, we assessed the effect of alfalfa (Medicago sativa L.) and two locally adapted forage legumes, bush clover (Lespedeza davurica S.) and milk vetch (Astragalus adsurgens Pall.) on the SOC concentration and SOC stock accumulated annually over a 2 m soil profile, and to estimate the long-term potential for SOC sequestration in the soil under the three forage legumes. The results showed that the concentration of SOC of the bare soil decreased slightly over the 7 years, while 7 years of legume growth substantially increased the concentration of SOC over the 0-2.0 m soil depth measured. Over the 7 year growth period the SOC stocks increased by 24.1, 19.9 and 14.6 Mg C ha-1 under the alfalfa, bush clover and milk vetch stands, respectively, and decreased by 4.2 Mg C ha-1 under bare soil. The sequestration of SOC in the 1-2 m depth of soil accounted for 79, 68 and 74 % of SOC sequestered through the upper 2 m of soil under alfalfa, bush clover and milk vetch, respectively. Conversion of arable land to perennial legume pasture resulted in a significant increase in SOC, particularly at soil depths below 1 m.

  3. Evaluating RGB photogrammetry and multi-temporal digital surface models for detecting soil erosion

    NASA Astrophysics Data System (ADS)

    Anders, Niels; Keesstra, Saskia; Seeger, Manuel

    2013-04-01

    Photogrammetry is a widely used tool for generating high-resolution digital surface models. Unmanned Aerial Vehicles (UAVs), equipped with a Red Green Blue (RGB) camera, have great potential in quickly acquiring multi-temporal high-resolution orthophotos and surface models. Such datasets would ease the monitoring of geomorphological processes, such as local soil erosion and rill formation after heavy rainfall events. In this study we test a photogrammetric setup to determine data requirements for soil erosion studies with UAVs. We used a rainfall simulator (5 m2) and above a rig with attached a Panasonic GX1 16 megapixel digital camera and 20mm lens. The soil material in the simulator consisted of loamy sand at an angle of 5 degrees. Stereo pair images were taken before and after rainfall simulation with 75-85% overlap. Acquired images were automatically mosaicked to create high-resolution orthorectified images and digital surface models (DSM). We resampled the DSM to different spatial resolutions to analyze the effect of cell size to the accuracy of measured rill depth and soil loss estimations, and determined an optimal cell size (thus flight altitude). Furthermore, the high spatial accuracy of the acquired surface models allows further analysis of rill formation and channel initiation related to e.g. surface roughness. We suggest implementing near-infrared and temperature sensors to combine soil moisture and soil physical properties with surface morphology for future investigations.

  4. Modeling pesticide volatilization: testing the additional effect of gaseous adsorption on soil solid surfaces.

    PubMed

    Garcia, Lucas; Bedos, Carole; Génermont, Sophie; Benoit, Pierre; Barriuso, Enrique; Cellier, Pierre

    2014-05-06

    Pesticide volatilization from bare soil exhibits usually a diurnal cycle with a potentially large decrease when the soil surface dries. We assume here that this decrease may be due to the increase in adsorption of gaseous pesticides to soil under dry conditions. Thus, a precise description of the change with time of water content of the soil surface and of additional process such as gaseous adsorption is required. We used the Volt'Air model: we first extended the van Genuchten curve to drier conditions and then inserted a partitioning coefficient of the pesticide between the air-filled pore space and the soil constituents. This coefficient was calculated by a quantum-chemistry-based method with a dependence on the Specific Surface Area of the soil (SSA) and Relative Humidity (RH) of the air-filled pore space. These developments were assessed by comparing with two data sets on volatilization of trifluralin applied to bare soil. The updated Volt'Air model allowed a better description of the volatilization dynamics on a diurnal cycle (increasing efficiency factor from 0.85 to 0.96 and -2.73 to 0.17 and decreasing RMSE from 146 to 78 and 353 to 168 for both scenarios) as well as the effect of a rewetting situation. Recommendations are made for further refining the description of this process together with the soil water conditions.

  5. Surface solubilization of phenanthrene by surfactant sorbed on soils with different organic matter contents.

    PubMed

    Ahn, Chi Kyu; Woo, Seung Han; Park, Jong Moon

    2010-05-15

    The effect of sorbed surfactant on the distribution of hydrophobic organic compounds (HOCs) during soil washing was investigated using a mathematical model. Phenanthrene (PHE) as an HOC and Triton X-100 (TX100) as a nonionic surfactant were used with two soils with low (SS) and high (BS) organic matter contents. The available carbon fraction (f(A,soil)(*)) after surfactant sorption was determined from surfactant coverage by measuring soil surface area using a methylene blue method. The sorbed surfactant was greatly effective as a sorbent for PHE, with an effectiveness factor (epsilon(soil)) in the range of 10.9-117.2 for SS and 39.7-121.3 for BS. Surface molar solubilization ratio (MSR(s)) and epsilon(soil) decreased with increasing TX100 dose. The MSR(s) decrement was lower for BS than for SS probably due to stronger affinity of PHE on organic matter in BS than in SS, which cause lower efficiency of soil washing than estimated by intrinsic sorption of PHE. These results suggest that soil washing in the field using surfactant for soils with high organic matter contents may give much lower efficiency than expected due to additional adsorption of HOC onto sorbed surfactant.

  6. Mapping Surface Soil Organic Carbon for Crop Fields with Remote Sensing

    NASA Technical Reports Server (NTRS)

    Chen, Feng; Kissel, David E.; West, Larry T.; Rickman, Doug; Luvall, J. C.; Adkins, Wayne

    2004-01-01

    The organic C concentration of surface soil can be used in agricultural fields to vary crop production inputs. Organic C is often highly spatially variable, so that maps of soil organic C can be used to vary crop production inputs using precision farming technology. The objective of this research was to demonstrate the feasibility of mapping soil organic C on three fields, using remotely sensed images of the fields with a bare surface. Enough soil samples covering the range in soil organic C must be taken from each field to develop a satisfactory relationship between soil organic C content and image reflectance values. The number of soil samples analyzed in the three fields varied from 22 to 26. The regression equations differed between fields, but gave highly significant relationships with R2 values of 0.93, 0.95, and 0.89 for the three fields. A comparison of predicted and measured values of soil organic C for an independent set of 2 soil samples taken on one of the fields gave highly satisfactory results, with a comparison equation of % organic C measured + 1.02% organic C predicted, with r2 = 0.87.

  7. Effects of soil layering on the characteristics of basin-edge induced surface waves

    NASA Astrophysics Data System (ADS)

    Narayan, Jay; Kumar, Sanjay

    2009-06-01

    This paper presents the effects of soil layering on the characteristics of basin-edge induced surface waves and associated strain and aggravation factor. The simulated results revealed surface wave generation near the basin-edge. The first mode of induced Love wave was obtained in models having increasing velocity with depth and a large impedance contrast between the soil layers. Amplitude amplification or de-amplification of body waves was proportional to the impedance contrast between the soil layers. The average aggravation factor was inversely proportional to the impedance contrast between the soil layers in case of increasingvelocity models and proportional in case of decreasing-velocity basinedge models. On the other hand, the maximum strain was inversely proportional to the impedance contrast between the soil layers in both cases. On the average, strain was greater in case of increasing-velocity models but the average aggravation factor was greater in case of decreasingvelocity models.

  8. Soil moisture sensing with aircraft observations of the diurnal range of surface temperature

    NASA Technical Reports Server (NTRS)

    Schmugge, T. J.; Blanchard, B.; Anderson, A.; Wang, V.

    1977-01-01

    Aircraft observations of the surface temperature were made by measurements of the thermal emission in the 8-14 micrometers band over agricultural fields around Phoenix, Arizona. The diurnal range of these surface temperature measurements were well correlated with the ground measurement of soil moisture in the 0-2 cm layer. The surface temperature observations for vegetated fields were found to be within 1 or 2 C of the ambient air temperature indicating no moisture stress. These results indicate that for clear atmospheric conditions remotely sensed surface temperatures are a reliable indicator of soil moisture conditions and crop status.

  9. Interception of Vapor Flow near Soil Surface for Water Conservation and Drought Alleviation

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Wang, Y.; Gao, Z.; Hishida, K.; Zhang, Y.

    2015-12-01

    Liquid and vapor flow of water in soil and the eventual vaporization of all waters near the soil surface are mechanisms controlling the near-surface evaporation. Interception and prevention of the vapor form of flow is critical for soil water conservation and drought alleviation in the arid and semiarid regions. Researches are conducted to quantify the amount of near-surface vapor flow in the semi-arid Loess Plateau of China and the central California of USA. Quantitative leaf water absorption and desorption functions were derived and tested based on laboratory experiments. Results show that plant leaves absorb and release water at different speeds depending on species and varieties. The "ideal" native plants in the dry climates can quickly absorb water and slowly release it. This water-holding capacity of a plant is characterized by the plant's water retention curves. Field studies are conducted to measure the dynamic water movements from the soil surface to ten meters below the surface in an attempt to quantify the maximum depths of water extraction due to different vegetation types and mulching measures at the surface. Results show that condensation is usually formed on soil surface membranes during the daily hours when the temperature gradients are inverted toward the soil surface. The soil temperature becomes stable at 13 Degree Celsius below the 4-meter depth in the Loess Plateau of China thus vapor flow is not likely deriving from deeper layers. However, the liquid flow may move in and out depending on water potential gradients and hydraulic conductivity of the layers. The near-surface vapor flow can be effectively intercepted by various mulching measures including gravel-and-sand cover, plant residue and plastic membranes. New studies are attempted to quantify the role of vapor flow for the survival of giant sequoias in the southern Sierra Nevada Mountains of California.

  10. Atrazine, triketone herbicides, and their degradation products in sediment, soil and surface water samples in Poland.

    PubMed

    Barchanska, Hanna; Sajdak, Marcin; Szczypka, Kornelia; Swientek, Angelika; Tworek, Martyna; Kurek, Magdalena

    2017-01-01

    The aim of this study was to monitor the sediment, soil and surface water contamination with selected popular triketone herbicides (mesotrione (MES) and sulcotrione(SUL)), atrazine (ATR) classified as a possible carcinogen and endocrine disrupting chemical, as well as their degradation products, in Silesia (Poland). Seventeen sediment samples, 24 soil samples, and 64 surface water samples collected in 2014 were studied. After solid-liquid extraction (SLE) and solid phase extraction (SPE), analytes were determined by high-performance liquid chromatography (HPLC) with diode array detection (DAD). Ten years after the withdrawal from the use, ATR was not detected in any of the collected samples; however, its degradation products are still present in 41 % of sediment, 71 % of soil, and 8 % of surface water samples. SUL was determined in 85 % of soil samples; its degradation product (2-chloro-4-(methylosulfonyl) benzoic acid (CMBA)) was present in 43 % of soil samples. In 17 % of sediment samples, CMBA was detected. Triketones were detected occasionally in surface water samples. The chemometric analysis (clustering analysis (CA), single-factor analysis of variance (ANOVA), N-Way ANOVA) was applied to find relations between selected soil and sediment parameters and herbicides concentration. In neither of the studied cases a statistically significant relationship between the concentrations of examined herbicides, their degradation products and soil parameters (organic carbon (OC), pH) was observed.

  11. Fixation of soil surface contamination using natural polysaccharides

    SciTech Connect

    Sackschewsky, M.R.

    1993-09-01

    Natural polysaccharides were evaluated as alternatives to commercially available dust-control agents for application in buried-waste and contaminated-soil remediation situations. Materials were identified and evaluated with specific criteria in mind: the materials must be environmentally benign and must not introduce any additional hazardous materials; they must be effective for at least 2 or 3 days, but they do not necessarily have to be effective for more than 2 to 3 weeks; they should be relatively resistant to light traffic; they must not interfere with subsequent soil treatment techniques, especially soil washing; and they must be relatively inexpensive. Two products, a pregelled potato starch and a mixture of carbohydrates derived from sugar beets, were selected for evaluation. Testing included small- and large-scale field demonstrations, laboratory physical property analyses, and wind-tunnel evaluations.

  12. Multi-frequency SAR data for soil surface moisture estimation over agricultural fields

    NASA Astrophysics Data System (ADS)

    Zribi, Mehrez; Baghdadi, Nicolas

    2015-04-01

    Soil moisture plays a crucial role in the continental water cycle, in particular through its influence on the distribution of precipitation between surface runoff and infiltration, which is the main driver behind most hydrological and geomorphologic processes. Although there is now a good understanding of soil hydrodynamics and water transfer in porous media, the development of reliable techniques allowing field heterogeneities to be fully analyzed in space and time remains a key issue. In recent decades, various inversion models have been proposed for the retrieval of surface parameters (mainly soil moisture and surface roughness) from Synthetic Aperture Radar (SAR) high resolution measurements. The proposed techniques depend particularly on two instrumental parameters: the radar system's spatial resolution and the number of configurations measured during satellite acquisitions (mainly incidence angle and polarization). In this paper, our objective is to illustrate different applications of SAR data to estimate soil moisture over bare soil and vegetation cover areas (wheat, olive groves, meadows ...). Potential of very high resolution data, with the availability of TerraSAR-X and COSMO-SkyMed constellations is also discussed. This study is based on different experimental campaigns organized over different sites in humid and semi-arid regions. Ground measurements (soil moisture, soil roughness, vegetation description) over test fields were carried out simultaneously to SAR measurements. Effect of vegetation attenuation on radar signal is considered through a synergy with optical remote sensing. Soil moisture precision for all proposed applications is generally ranged between 3 and 5% of volumetric moisture. These methodologies are developed in the context of the preparation for having a high soil moisture operational product, with SENTINEL and/or the other planned constellations. After an analysis of radar data sensitivity (C and X bands) to surface parameters

  13. Control of cation concentrations in stream waters by surface soil processes in an Amazonian watershed

    NASA Astrophysics Data System (ADS)

    Markewitz, Daniel; Davidson, Eric A.; Figueiredo, Ricardo de O.; Victoria, Reynaldo L.; Krusche, Alex V.

    2001-04-01

    The chemical composition of ground waters and stream waters is thought to be determined primarily by weathering of parent rock. In relatively young soils such as those occurring in most temperate ecosystems, dissolution of primary minerals by carbonic acid is the predominant weathering pathway that liberates Ca2+, Mg2+ and K+ and generates alkalinity in the hydrosphere. But control of water chemistry in old and highly weathered soils that have lost reservoirs of primary minerals (a common feature of many tropical soils) is less well understood. Here we present soil and water chemistry data from a 10,000-hectare watershed on highly weathered soil in the Brazilian Amazon. Streamwater cation concentrations and alkalinity are positively correlated to each other and to streamwater discharge, suggesting that cations and bicarbonate are mainly flushed from surface soil layers by rainfall rather than being the products of deep soil weathering carried by groundwater flow. These patterns contrast with the seasonal patterns widely recognized in temperate ecosystems with less strongly weathered soils. In this particular watershed, partial forest clearing and burning 30years previously enriched the soils in cations and so may have increased the observed wet season leaching of cations. Nevertheless, annual inputs and outputs of cations from the watershed are low and nearly balanced, and thus soil cations from forest burning will remain available for forest regrowth over the next few decades. Our observations suggest that increased root and microbial respiration during the wet season generates CO2 that drives cation-bicarbonate leaching, resulting in a biologically mediated process of surface soil exchange controlling the streamwater inputs of cations and alkalinity from these highly weathered soils.

  14. Simulating multi-angle imaging spectro-radiometer (MISR) sampling and retrieval of soil surface roughness and composition changes using a bi-directional soil spectral reflectance model

    USDA-ARS?s Scientific Manuscript database

    Soil surface changes due to soil erosion can be detected by ground-based, hyper-spectral measurements of angular reflectance and a bi-directional soil spectral reflectance model. The next generation of wind and water erosion models should incorporate directional remote sensing data to improve large ...

  15. Surface soil moisture retrieval using the L-band synthetic aperture radar onboard the Soil Moisture Active Passive satellite and evaluation at core validation sites

    USDA-ARS?s Scientific Manuscript database

    This paper evaluates the retrieval of soil moisture in the top 5-cm layer at 3-km spatial resolution using L-band dual-copolarized Soil Moisture Active Passive (SMAP) synthetic aperture radar (SAR) data that mapped the globe every three days from mid-April to early July, 2015. Surface soil moisture ...

  16. Estimation of Bare Surface Soil Moisture and Surface Roughness Parameter Using L-Band SAR Image Data

    NASA Technical Reports Server (NTRS)

    Shi, Jian-Cheng; Wang, James; Hsu, Ann Y.; ONeill, Peggy E.; Engman, Edwin T.

    1997-01-01

    An algorithm based on a fit of the single-scattering Integral Equation Method (IEM) was developed to provide estimation of soil moisture and surface roughness parameter (a combination of rms roughness height and surface power spectrum) from quad-polarized synthetic aperture radar (SAR) measurements. This algorithm was applied to a series of measurements acquired at L-band (1.25 GHz) from both AIRSAR (Airborne Synthetic Aperture Radar operated by the Jet Propulsion Laboratory) and SIR-C (Spaceborne Imaging Radar-C) over a well- managed watershed in southwest Oklahoma. Prior to its application for soil moisture inversion, a good agreement was found between the single-scattering IEM simulations and the L band measurements of SIR-C and AIRSAR over a wide range of soil moisture and surface roughness conditions. The sensitivity of soil moisture variation to the co-polarized signals were then examined under the consideration of the calibration accuracy of various components of SAR measurements. It was found that the two co-polarized backscattering coefficients and their combinations would provide the best input to the algorithm for estimation of soil moisture and roughness parameter. Application of the inversion algorithm to the co-polarized measurements of both AIRSAR and SIR-C resulted in estimated values of soil moisture and roughness parameter for bare and short-vegetated fields that compared favorably with those sampled on the ground. The root-mean-square (rms) errors of the comparison were found to be 3.4% and 1.9 dB for soil moisture and surface roughness parameter, respectively.

  17. Revegetation of Acid Rock Drainage (ARD) Producing Slope Surface Using Phosphate Microencapsulation and Artificial Soil

    NASA Astrophysics Data System (ADS)

    Kim, Jae Gon

    2017-04-01

    Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fe-phosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

  18. Modeling and measurement of microwave emission and backscattering from bare soil surfaces

    NASA Technical Reports Server (NTRS)

    Saatchi, S.; Wegmuller, U.

    1992-01-01

    A multifrequency ground-based radiometer-scatterometer system working at frequencies between 3.0 GHz and 11.0 GHz has been used to study the effect of soil moisture and roughness on microwave emission and backscattering. The freezing and thawing effect of the soil surface and the changes of the surface roughness due to rain and erosion are reported. To analyze the combined active and passive data, a scattering model based on physical optics approximation for the low frequency and geometrical optics approximation for high frequency has been developed. The model is used to calculate the bistatic scattering coefficients from the surface. By considering the conservation of energy, the result has been integrated over a hemisphere above the surface to calculate the emissivity. The backscattering and emission model has been coupled with the observed data in order to extract soil moisture and surface roughness.

  19. Modeling and measurement of microwave emission and backscattering from bare soil surfaces

    NASA Technical Reports Server (NTRS)

    Saatchi, S.; Wegmuller, U.

    1992-01-01

    A multifrequency ground-based radiometer-scatterometer system working at frequencies between 3.0 GHz and 11.0 GHz has been used to study the effect of soil moisture and roughness on microwave emission and backscattering. The freezing and thawing effect of the soil surface and the changes of the surface roughness due to rain and erosion are reported. To analyze the combined active and passive data, a scattering model based on physical optics approximation for the low frequency and geometrical optics approximation for high frequency has been developed. The model is used to calculate the bistatic scattering coefficients from the surface. By considering the conservation of energy, the result has been integrated over a hemisphere above the surface to calculate the emissivity. The backscattering and emission model has been coupled with the observed data in order to extract soil moisture and surface roughness.

  20. A time-series approach to estimating soil moisture from vegetated surfaces using L-band radar backscatter

    USDA-ARS?s Scientific Manuscript database

    Many previous studies have shown the sensitivity of radar backscatter to surface soil moisture content, particularly at L-band. Moreover, the estimation of soil moisture from radar for bare soil surfaces is well-documented, but estimation underneath a vegetation canopy remains unsolved. Vegetation s...

  1. Temporal observations of surface soil moisture using a passive microwave sensor

    NASA Technical Reports Server (NTRS)

    Jackson, T. J.; O'Neill, P.

    1987-01-01

    A series of 10 aircraft flights was conducted over agricultural fields to evaluate relationships between observed surface soil moisture and soil moisture predicted using passive microwave sensor observations. An a priori approach was used to predict values of surface soil moisture for three types of fields: tilled corn, no-till corn with soybean stubble, and idle fields with corn stubble. Acceptable predictions were obtained for the tilled corn fields, while poor results were obtained for the others. The source of error is suspected to be the density and orientation of the surface stubble layer; however, further research is needed to verify this explanation. Temporal comparisons between observed, microwave predicted, and soil water-simulated moisture values showed similar patterns for tilled well-drained fields. Divergences between the observed and simulated measurements were apparent on poorly drained fields. This result may be of value in locating and mapping hydrologic contributing areas.

  2. Using Multi-Dimensional Microwave Remote Sensing Information for the Retrieval of Soil Surface Roughness

    NASA Astrophysics Data System (ADS)

    Marzahn, P.; Ludwig, R.

    2016-06-01

    In this Paper the potential of multi parametric polarimetric SAR (PolSAR) data for soil surface roughness estimation is investigated and its potential for hydrological modeling is evaluated. The study utilizes microwave backscatter collected from the Demmin testsite in the North-East Germany during AgriSAR 2006 campaign using fully polarimetric L-Band airborne SAR data. For ground truthing extensive soil surface roughness in addition to various other soil physical properties measurements were carried out using photogrammetric image matching techniques. The correlation between ground truth roughness indices and three well established polarimetric roughness estimators showed only good results for Re[ρRRLL] and the RMS Height s. Results in form of multitemporal roughness maps showed only satisfying results due to the fact that the presence and development of particular plants affected the derivation. However roughness derivation for bare soil surfaces showed promising results.

  3. Soil surface searching and transport of Euphorbia characias seeds by ants

    NASA Astrophysics Data System (ADS)

    Espadaler, Xavier; Gómez, Crisanto

    The intensity of exploring the soil surface by ants was studied for the four species involved in the dispersal and predation of seeds of the West-Mediterranean myrmecochorous plant Euphorbia characias. During the dehiscence period (June) the whole soil surface is sccanned in 43 minutes. Not all ants that find a seed take it to the nest. For the four ant species studied ( Pheidole pallidula, Aphaenogaster senilis, Tapinoma nigerrimum, Messor barbarus) the proportion of ants that finally take the seed is 67.6%. In spite of this, the high level of soil surface searching explains the rather short time that seeds remain on the soil before being removed. The presence of an elaiosome is a key element in the outcome of the ant-seed interaction: a seed with elaiosome has a seven-fold increase in probability of being taken to the nest if found by a non-granivorous ant. The predator-avoidance hypothesis for myrmecochory is supported.

  4. [Influence of different types of surface on the diversity of soil fauna in Beijing Olympic Park].

    PubMed

    Song, Ying-shi; Li, Xiao-wen; Li, Feng; Li, Hai-mei

    2015-04-01

    Soil fauna are impacted by urbanization. In order to explore the stress of different surface covers on diversity and community structure of soil fauna, we conducted this experiment in Beijing Olympic Park. In autumn of 2013, we used Baermann and Tullgren methods to study the diversity of soil fauna in the depth of 0-5 cm, 5-10 cm, 10-15 cm under four different land covers i.e. bared field (BF), totally impervious surface (TIS), partly impervious surface (PIS) and grassland (GL). The results showed that the total number of soil fauna in 100 cm3 was in order of GL (210) > PIS (193) > TIS (183) > BF (90), and the number of nematodes accounted for 72.0%-92.8% of the total number. On the vertical level, except for the TIS, the other three types of surface soil fauna had the surface gathered phenomenon. The Shannon diversity index and the Pielou evenness index of BF were lower, but the Simpson dominance index was higher than in the other land covers. The Shannon index and Margalef richness indes of GL were higher than those of the other land covers. The Shannon indexes of TIS and PIS were between the BF and GL. Except for the TIS and GL, the similarity indexes were between 0.4-0.5, indicating moderate non-similar characteristics. The diversity of soil fauna was significantly correlated with temperature, pH and available potassium.

  5. Potential use of copper as a hygienic surface; problems associated with cumulative soiling and cleaning.

    PubMed

    Airey, P; Verran, J

    2007-11-01

    It has been suggested that antibacterial copper could be used in place of stainless steel to help reduce the occurrence of hospital-acquired infections. The antibacterial activity of copper has been clearly demonstrated when using cell suspensions held in prolonged contact with copper or copper alloys. The aim of this study was to evaluate the antimicrobial properties of copper in comparison with stainless steel in a generally dry environment. Three stainless steels of varying surface finish and polished copper were soiled with Staphylococcus aureus suspended in a protein-based organic soil (bovine serum album), dried rapidly, and then incubated for 24 h. Surfaces were then wiped clean using a standardised wiping procedure with two cleaning agents recommended by UK National Health Service guidelines. This soiling/cleaning procedure was carried out daily over five days. After each cleaning cycle the amount of residual soil and live cells was assessed using direct epifluorescence microscopy. All materials were easily cleaned after the first soiling episode but a build-up of cells and soil was observed on the copper surfaces after several cleaning/wiping cycles. Stainless steel remained highly cleanable. Accumulation of material on copper is presumably due to the high reactivity of copper, resulting in surface conditioning. This phenomenon will affect subsequent cleaning, aesthetic properties and possibly antibacterial performance. It is important to select the appropriate cleaning/disinfecting protocols for selected surfaces.

  6. Modeling spatial and seasonal soil moisture in a semi arid hillslope: The impact of integrating soil surface seal parameters

    NASA Astrophysics Data System (ADS)

    Sela, Shai; Svoray, Tal; Assouline, Shmuel

    2010-05-01

    Modeling hillslope hydrology and the complex and coupled reaction of runoff processes to rainfall, lies in the focus of a growing number of research studies. The ability to characterize and understand the mechanisms underlying the complex hillslope soil moisture patterns, which trigger spatially variable non linear runoff initiation, still remains a current hydrological challenge especially in ungauged catchments. In humid climates, connectivity of transient moisture patches was suggested as a unifying concept for studying thresholds for subsurface flow and redistribution of soil moisture at the hillslope scale. In semiarid areas, however, transient moisture patches control also the differentiation between evaporation and surface runoff and the ability to identify a unifying concept controlling the large variability of soil moisture at the hillslope scale remains an open research gap. At the LTER Lehavim site in the center of Israel (31020' N, 34045' E) a typical hillslope (0.115 km2) was chosen offering different aspects and a classic geomorphologic banding. The annual rainfall is 290 mm, the soils are brown lithosols and arid brown loess and the dominant rock formations are Eocenean limestone and chalk with patches of calcrete. The vegetation is characterised by scattered dwarf shrubs (dominant species Sarcopoterium spinosum) and patches of herbaceous vegetation, mostly annuals, are spread between rocks and dwarf shrubs. An extensive spatial database of soil hydraulic and environmental parameters (e.g. slope, radiation, bulk density) was measured in the field and interpolated to continuous maps using geostatistical techniques and physically based modelling. To explore the effect of soil surface sealing, Mualem and Assouline (1989) equations describing the change in hydraulic parameters resulting from soil seal formation were applied. Two simple indices were developed to describe local evaporation values and contribution of water from rock outcrops to the soil

  7. Observations of flow path interactions with surface structures during initial soil development stage using irrigation experiments

    NASA Astrophysics Data System (ADS)

    Bartl, Steffen; Biemelt, Detlef; Badorreck, Annika; Gerke, Horst H.

    2010-05-01

    Structures and processes are dynamically linked especially during initial stages of soil and ecosystem development. Here we assume that soil pore structures and micro topography determine the flow paths and water fluxes as well as further structure changes. Reports about flow path developments at the soil surface are still limited because of an insufficient knowledge of the changing micro topography at the surface. The objective of this presentation is to evaluate methods for parameterisation of surface micro topography for analysing interactions between infiltration and surface runoff. Complex irrigation experiments were carried out at an experimental site in the neighbourhood of the artificially created water catchment "Chicken Creek". The irrigation rates between 160 mm/h and 250 mm/h were held constant over a time period of 20 minutes. The incoming intensities were measured as well as the raindrop-velocity and -size distributions. The surface runoff was continuously registered, soil samples were taken, and soil water potential heads were monitored using tensiometers. Surface and subsurface flow paths were identified using different tracers. The soil surface structures were recorded using a high resolution digital camera before, during, and after irrigation. Micro topography was surveyed using close-range photogrammetry. With this experimental design both, flow paths on the surface and in the soil as well as structure and texture changes could be observed simultaneously. In 2D vertical cross-sections, the effect of initial sediment deposition structure on infiltration and runoff was observed. Image analysis of surface pictures allowed identifying structural and soil textural changes during the runoff process. Similar structural changes related to surface flow paths were found with the photogrammetric surface analysis. We found evidence for the importance of the initial structures on the flow paths as well as a significant influence of the system development

  8. Estimating surface turbulent heat fluxes from land surface temperature and soil moisture observations using the particle batch smoother

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Dong, Jianzhi; Steele-Dunne, Susan C.; van de Giesen, Nick

    2016-11-01

    Surface heat fluxes interact with the overlying atmosphere and play a crucial role in meteorology, hydrology, and climate change studies, but in situ observations are costly and difficult. It has been demonstrated that surface heat fluxes can be estimated from assimilation of land surface temperature (LST). One approach is to estimate a neutral bulk heat transfer coefficient (CHN) to scale the sum of turbulent heat fluxes, and an evaporative fraction (EF) that represents the partitioning between fluxes. Here the newly developed particle batch smoother (PBS) is implemented. The PBS makes no assumptions about the prior distributions and is therefore well-suited for non-Gaussian processes. It is also particularly advantageous for parameter estimation by tracking the entire prior distribution of parameters using Monte Carlo sampling. To improve the flux estimation on wet or densely vegetated surfaces, a simple soil moisture scheme is introduced to further constrain EF, and soil moisture observations are assimilated simultaneously. This methodology is implemented with the FIFE 1987 and 1988 data sets. Validation against observed fluxes indicates that assimilating LST using the PBS significantly improves the flux estimates at both daily and half-hourly timescales. When soil moisture is assimilated, the estimated EFs become more accurate, particularly when the surface heat flux partitioning is energy-limited. The feasibility of extending the methodology to use remote sensing observations is tested by limiting the number of LST observations. Results show that flux estimates are greatly improved after assimilating soil moisture, particularly when LST observations are sparse.

  9. Cross-satellite comparison of operational land surface temperature products derived from MODIS and ASTER data over bare soil surfaces

    NASA Astrophysics Data System (ADS)

    Duan, Si-Bo; Li, Zhao-Liang; Cheng, Jie; Leng, Pei

    2017-04-01

    The collection 6 (C6) MODIS land surface temperature (LST) product is publicly available for the user community. Compared to the collection 5 (C5) MODIS LST product, the C6 MODIS LST product has been refined over bare soil pixels. Assessing the accuracy of the C6 MODIS LST product will help to facilitate the use of the LST product in various applications. In this study, we present a cross-satellite comparison to evaluate the accuracy of the C6 MODIS LST product (MOD11_L2) over bare soil surfaces under various atmospheric and surface conditions using the ASTER LST product as a reference. For comparison, the C5 MODIS LST product was also used in the analysis. The absolute biases (0.2-1.5 K) of the differences between the C6 MODIS LST and ASTER LST over bare soil surfaces are approximately two times less than those (0.6-3.8 K) of the differences between the C5 MODIS LST and ASTER LST. Furthermore, the RMSEs (0.7-2.3 K) over bare soil surfaces for the C6 MODIS LST are significantly smaller than those (0.9-4.2 K) for the C5 MODIS LST. These results indicate that the accuracy of the C6 MODIS LST product is much better than that of the C5 MODIS LST product. We recommend that the user community employs the C6 MODIS LST product in their applications.

  10. Soil surface carbon dioxide efflux of bioenergy cropping systems

    USDA-ARS?s Scientific Manuscript database

    Bioenergy cropping systems have been proposed as a way to enhance United States energy security. However, research on greenhouse gas emissions from such systems is needed to ensure environmental sustainability in the field. Since soil aeration properties are dynamic, high-resolution data are needed ...

  11. Microscope Image of a Martian Soil Surface Sample

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is the closest view of the material underneath NASA's Phoenix Mars Lander. This sample was taken from the top centimeter of the Martian soil, and this image from the lander's Optical Microscope demonstrates its overall composition.

    The soil is mostly composed of fine orange particles, and also contains larger grains, about a tenth of a millimeter in diameter, and of various colors. The soil is sticky, keeping together as a slab of material on the supporting substrate even though the substrate is tilted to the vertical.

    The fine orange grains are at or below the resolution of the Optical Microscope. Mixed into the soil is a small amount&mdashabout 0.5 percent&mdashof white grains, possibly of a salt. The larger grains range from black to almost transparent in appearance. At the bottom of the image, the shadows of the Atomic Force Microscope (AFM) beams are visible. This image is 1 millimeter x 2 millimeters.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by JPL, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

  12. Soil Moisture Monitoring using Surface Electrical Resistivity measurements

    NASA Astrophysics Data System (ADS)

    Calamita, Giuseppe; Perrone, Angela; Brocca, Luca; Straface, Salvatore

    2017-04-01

    The relevant role played by the soil moisture (SM) for global and local natural processes results in an explicit interest for its spatial and temporal estimation in the vadose zone coming from different scientific areas - i.e. eco-hydrology, hydrogeology, atmospheric research, soil and plant sciences, etc... A deeper understanding of natural processes requires the collection of data on a higher number of points at increasingly higher spatial scales in order to validate hydrological numerical simulations. In order to take the best advantage of the Electrical Resistivity (ER) data with their non-invasive and cost-effective properties, sequential Gaussian geostatistical simulations (sGs) can be applied to monitor the SM distribution into the soil by means of a few SM measurements and a densely regular ER grid of monitoring. With this aim, co-located SM measurements using mobile TDR probes (MiniTrase), and ER measurements, obtained by using a four-electrode device coupled with a geo-resistivimeter (Syscal Junior), were collected during two surveys carried out on a 200 × 60 m2 area. Two time surveys were carried out during which Data were collected at a depth of around 20 cm for more than 800 points adopting a regular grid sampling scheme with steps (5 m) varying according to logistic and soil compaction constrains. The results of this study are robust due to the high number of measurements available for either variables which strengthen the confidence in the covariance function estimated. Moreover, the findings obtained using sGs show that it is possible to estimate soil moisture variations in the pedological zone by means of time-lapse electrical resistivity and a few SM measurements.

  13. Soil particle tracing using RFID tags for elucidating the behavior of radiocesium on bare soil surfaces in Fukushima

    NASA Astrophysics Data System (ADS)

    Manome, Ryo; Onda, Yuichi; Patin, Jeremy; Stefani, Chiara; Yoshimura, Kazuya; Parsons, Tony; Cooper, James

    2014-05-01

    Radioactive materials are generally associated with soil particles in terrestrial environment and therefore the better understanding soil erosion processes is expected to improve the mitigation of radioactive risks. Spatial variability in soil erosion has been one of critical issues for soil erosion management. This study attempts to track soil particle movement on soil surfaces by employing Radio Frequency Identification (RFID) tags for the better understanding radiocesium behavior. A RFID tag contains a specific electronically identifier and it permits tracing its movement by reading the identifier. In this study, we made artificial soil particles by coating the RFID tags with cement material. The particle diameters of the artificial soil particles approximately ranged from 3 to 5 mm. The artificial soil particles were distributed in a reticular pattern on a soil erosion plot (bare soil surface, 22.13 m length × 5 m width, 4.4° slope) in Kawamata town where radiocesium deposited because of the Fukushima Dai-ichi power plant accident. After their distribution on October 2012, we had read the identifiers of RFID tags and recorded their locations on the plot for 14 times by September 2013. Moving distance (MD) was calculated based on the difference of the location for each sampling date. The topographical changes on the plot were also monitored with a laser scanner to describe interrill erosion and rill erosion area on 11occasions. Median MD is 10.8cm for all the observations. Median MD on interrill and rill erosion areas were 9.8 cm and 20.7 cm, respectively. Seasonal variation in MD was observed; an extremely large MD was found in May 2013, at the first reading after the winter season. This large MD after winter suggests that snowmelt runoff was the dominant process which transported the soil particles. Comparing the MD with the observed amounts of rainfall, sediment and runoff on the plot, significant positive correlation were found if the data of May, 2013

  14. Phosphatase activity in the surface and buried chestnut soils of the Volga-Don interfluve

    NASA Astrophysics Data System (ADS)

    Khomutova, T. E.; Demkina, T. S.; Kashirskaya, N. N.; Demkin, V. A.

    2012-04-01

    The phosphatase activity (PA) was studied in the chestnut paleosols buried in 1718-1720 under the Anna Ivanovna rampart in the southern part of the Privolzhskaya Upland and in the middle of the third millennium BC under the burial mound of the Bronze Age on the Northern Yergeni Upland; the background analogues of these soils were also examined. The PA values in the fresh soil samples varied from 2.5 to 37 mg of P2O5/10 g of soil per h with maximums in the A1 horizon of the surface soils and in the B1 horizon of the paleosols. The PA values depended on the time of storage of the samples: with time, they increased by 2.6-2.9 times in the A1 horizon of the background surface soil and decreased by 20-60% in the other soil samples. The specific distribution patterns of the PA values in the soil profiles remained the same independently of the time of storage of the samples. Relatively small amounts of the soil samples were sufficient for the reliable determination of the PA: 1-2 g for the A1 horizon and 3-5 g for the B1 and B2 horizons. The time of incubation with the substrate had to be increased up to 4 h for the long-stored samples.

  15. Surface temperature and soil moisture retrieval in the Sahel from airborne multifrequency microwave radiometry

    SciTech Connect

    Calvet, J.C.

    1996-03-01

    Bipolarized microwave brightness temperatures of Sahel semiarid landscapes are analyzed at two frequencies: 5.05 and 36.5 GHz. These measurements were performed in Niger, West Africa, by the radiometer PORTOS in the framework of the Hydrologic Atmospheric Pilot Experiment in the Sahel (HAPEX-Sahel), during the end of the rainy season (August--September 1992). The airborne microwave data were collected simultaneously with radiosoundings of the atmosphere, and ground measurements of surface temperature, soil moisture, and biomass of several vegetation types. After estimating the soil roughness parameters, it is shown that two kinds of vegetation canopies must be considered: sparse canopies and patchy canopies including bare soil strips. The mixed soil vegetation microwave emission is analyzed using a random continuous approach. The sparse canopy emission is efficiently described by considering the vegetation layer as homogeneous. Conversely, a simple soil-vegetation mixing equation must be used for the patchy canopies. The problem with retrieving the canopy temperature and the near-surface soil moisture is addressed. For every canopy, soil moisture retrieval is possible. Soil moisture maps are proposed. The canopy temperature can also be retrieved with good accuracy provided both vertical (v) and horizontal (h) polarizations are available. It is shown that the retrieved variables can be used to separate landscape units through a classification procedure.

  16. Survival of Pochonia chlamydosporia on the soil surface after different exposure intervals at ambient conditions.

    PubMed

    Fernandes, Rafael Henrique; Lopes, Everaldo Antônio; Borges, Darlan Ferreira; Bontempo, Amanda Ferreira; Zanuncio, José Cola; Serrão, José Eduardo

    2017-09-25

    Exposure of the nematophagous fungus Pochonia chlamydosporia to solar radiation and elevated temperatures before being incorporated into the soil can reduce its survival and efficiency as biocontrol agent. A field experiment was carried out to assess the effect of the exposure period on the viability of P. chlamydosporia applied on the soil surface. A commercial bionematicide based on P. chlamydosporia was sprayed on soil, and soil samples were collected before and at 0, 30, 60, 90, 120, and 150min after fungal application. Relative humidity (RH), the irradiance (IR), air temperature (AT), and soil temperature (ST) were recorded. The number of P. chlamydosporia colony forming units (CFUs) was evaluated after 20 days of incubation. P. chlamydosporia survival decreased over the time of exposure on the soil surface. Overall, the number of CFUs decreased by more than 90% at 150min after application. Exposure to RH ≥61%, ST and AT between 25-35°C and 19-29°C, and IR between 1172 and 2126μmol of photons m(-2)s(-1) induced a negative exponential effect on the survival of the fungus over the time. Exposure to climatic conditions on the soil surface reduces P. chlamydosporia viability. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  17. Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid

    PubMed Central

    Donaldson, Melissa A.; Bish, David L.; Raff, Jonathan D.

    2014-01-01

    Nitrous acid (HONO) is an important hydroxyl (OH) radical source that is formed on both ground and aerosol surfaces in the well-mixed boundary layer. Recent studies report the release of HONO from nonacidic soils, although it is unclear how soil that is more basic than the pKa of HONO (∼3) is capable of protonating soil nitrite to serve as an atmospheric HONO source. Here, we used a coated-wall flow tube and chemical ionization mass spectrometry (CIMS) to study the pH dependence of HONO uptake onto agricultural soil and model substrates under atmospherically relevant conditions (1 atm and 30% relative humidity). Experiments measuring the evolution of HONO from pH-adjusted surfaces treated with nitrite and potentiometric titrations of the substrates show, to our knowledge for the first time, that surface acidity rather than bulk aqueous pH determines HONO uptake and desorption efficiency on soil, in a process controlled by amphoteric aluminum and iron (hydr)oxides present. The results have important implications for predicting when soil nitrite, whether microbially derived or atmospherically deposited, will act as a net source or sink of atmospheric HONO. This process represents an unrecognized mechanism of HONO release from soil that will contribute to HONO emissions throughout the day. PMID:25512517

  18. Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns.

    PubMed

    Simpson, Catherine R; Nelson, Shad D; Stratmann, Jerry E; Ajwa, Husein A

    2010-06-01

    Metam-sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off-gassing rate of MITC. Off-gassing rate was consistently reduced with increasing water seal application. The application of a 2.5-3.8 cm water seal provided significantly lower (71-74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off-gassing was observed in the 2.5 cm water seal. This suggests that volatilization of MITC-generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench-scale soil column studies. .

  19. Retention of potentially mobile radiocesium in forest surface soils affected by the Fukushima nuclear accident

    PubMed Central

    Koarashi, Jun; Moriya, Koichi; Atarashi-Andoh, Mariko; Matsunaga, Takeshi; Fujita, Hiroki; Nagaoka, Mika

    2012-01-01

    The fate of 137Cs derived from the Fukushima nuclear accident fallout and associated radiological hazards are largely dependent on its mobility in the surface soils of forest ecosystems. Thus, we quantified microbial and adsorptive retentions of 137Cs in forest surface (0–3 cm) soils. The K2SO4 extraction process liberated 2.1%–12.8% of the total 137Cs from the soils. Two soils with a higher content of clay- and silt-sized particles, organic carbon content, and cation exchange capacity showed higher 137Cs extractability. Microbial biomass was observed in all of the soils. However, the 137Cs extractability did not increase after destruction of the microbial biomass by chloroform fumigation, providing no evidence for microbial retention of the Fukushima-fallout 137Cs. The results indicate that uptake of 137Cs by soil microorganisms is less important for retention of potentially mobile 137Cs in the forest surface soils compared to ion-exchange adsorption on non-specific sites provided by abiotic components. PMID:23256039

  20. Soil surface acidity plays a determining role in the atmospheric-terrestrial exchange of nitrous acid.

    PubMed

    Donaldson, Melissa A; Bish, David L; Raff, Jonathan D

    2014-12-30

    Nitrous acid (HONO) is an important hydroxyl (OH) radical source that is formed on both ground and aerosol surfaces in the well-mixed boundary layer. Recent studies report the release of HONO from nonacidic soils, although it is unclear how soil that is more basic than the pKa of HONO (∼ 3) is capable of protonating soil nitrite to serve as an atmospheric HONO source. Here, we used a coated-wall flow tube and chemical ionization mass spectrometry (CIMS) to study the pH dependence of HONO uptake onto agricultural soil and model substrates under atmospherically relevant conditions (1 atm and 30% relative humidity). Experiments measuring the evolution of HONO from pH-adjusted surfaces treated with nitrite and potentiometric titrations of the substrates show, to our knowledge for the first time, that surface acidity rather than bulk aqueous pH determines HONO uptake and desorption efficiency on soil, in a process controlled by amphoteric aluminum and iron (hydr)oxides present. The results have important implications for predicting when soil nitrite, whether microbially derived or atmospherically deposited, will act as a net source or sink of atmospheric HONO. This process represents an unrecognized mechanism of HONO release from soil that will contribute to HONO emissions throughout the day.

  1. Photodegradation of antibiotics on soil surfaces: laboratory studies on sulfadiazine in an ozone-controlled environment.

    PubMed

    Wolters, André; Steffens, Markus

    2005-08-15

    Among the processes affecting transport and degradation of antibiotics released to the environment during application of manure and slurry to agricultural land, photochemical transformations are of particular interest. Drying-out of the top soil layer under field conditions enables sorption of surface-applied antibiotics to soil dust, thus facilitating direct, indirect, and sensitized photodegradation at the soil/atmosphere interface. For studying various photochemical transformation processes of sulfadiazine, a photovolatility chamber designed in accordance with the requirements of the USEPA Guideline and 161-3 was used. Application of 14C-labeled sulfadiazine enabled complete mass balances and allowed for investigating the impact of various surfaces (glass and soil dust) and environmental factors, i.e., irradiation and atmospheric ozone, on photodegradation and volatilization. Volatilization was shown to be a negligible process. Even after increasing the air temperature up to 35 degrees C only minor amounts of sulfadiazine and transformation products (0.01-0.28% of applied radioactivity) volatilized. Due to direct and indirect photodegradation, the highest extent of mineralization to 14CO2 (3.9%), the formation of degradation products and of nonextractable soil residues was measured in irradiated soil dust experiments using ozone concentrations of 200 ppb. However, even in the dark significant mineralization was observed when ozone was present, indicating ozone-controlled transformation of sulfadiazine to occur at the soil surface.

  2. Organochlorine pesticides contamination in surface soils from two pesticide factories in Southeast China.

    PubMed

    Zhang, Lifei; Dong, Liang; Shi, Shuangxin; Zhou, Li; Zhang, Ting; Huang, Yeru

    2009-10-01

    The present article attempts to investigate organochlorine pesticides' (OCPs) contamination in soils from polluted sites and to assess the soil quality in the study area. HCHs and eight other persistent organic pollutants (POPs) pesticides were studied in surface soil samples collected from a new (F) and an old (G) pesticide factory in Southeast China. According to the measured results, surface soils from F and G were contaminated with HCHs, DDTs, HCB, and chlordane, with beta-HCH and p,p'-DDT being the two dominant substances. The total OCPs concentrations of surface soils from F and G were 0.84 and 166mgkg(-1) respectively. Cluster analysis was performed to group the soil sites in terms of their total OCPs contamination levels. The ratios of alpha-HCH/gamma-HCH, o,p'-DDT/p,p'-DDT, and trans-/cis- chlordane in some of the soil samples are similar to their technical products in the study area which indicates the lack of hazardous waste management practices of the pesticide production and transportation. According to GB 15618-1995, the HCHs could be classified as light pollution and little pollution for F and G, whereas DDTs levels of F and G could be defined as little pollution and heavy pollution, respectively. This study indicates that surface soils, especially residential area soils from F and G were facing varying degrees of pollutions. The situation is more hazardous due to the continuous exposure of the population that lives in the surroundings. Therefore, on-site remediation technologies and the best available techniques/best environmental practices (BAT/BEP) should be carried out on these factories with the national implementation of the Stockholm Convention.

  3. Mapping the total phosphorus concentration of biosolid amended surface soils using LANDSAT TM data.

    PubMed

    Sridhar, B B Maruthi; Vincent, Robert K; Witter, Jason D; Spongberg, Alison L

    2009-04-01

    Conventional methods for soil sampling and analysis for soil variability in chemical characteristics are too time-consuming and expensive for multi-seasonal monitoring over large-scale areas. Hence, the objectives of this study are: 1) to determine changes in chemical concentrations of soils that are amended with treated sewage sludge; and 2) to determine if LANDSAT TM data can be used to map surface chemical characteristics of such amended soils. For this study, we selected two fields in NW Ohio, designated as F34 and F11, that had been applied with 34 and 11 ton acre(-1) of biosolids, respectively. Soil samples from a total of 70 sampling locations across the two fields were collected one day prior to LANDSAT 5 overpass and were analyzed for several elemental concentrations. The accumulation of Ba, Cd, Cu, S and P were found to be significantly higher in the surface soils of field F34, compared to field F11. Regression equations were established to search for algorithms that could map these five elemental concentrations in the surface soils using six, dark-object-subtracted (DOS) LANDSAT TM bands and the 15 non-reciprocal spectral ratios derived from these six bands for the May 20, 2005, LANDSAT 5 TM image. Phosphorus (P) had the highest R(2) adjusted value (67.9%) among all five elements considered, and the resulting algorithm employed only spectral ratios. This model was successfully tested for robustness by applying it to another LANDSAT TM image obtained on June 5, 2005. Our results enabled us to conclude that LANDSAT TM imagery of bare-soil fields can be used to quantify and map the spatial variation of total phosphorous concentration in surface soils. This research has significant implications for identification and mapping of areas with high P, which is important for implementing and monitoring the best phosphorous management practices across the region.

  4. Definition of initial conditions and soil profile depth for Hydrological Land Surface Models in Cold Regions

    NASA Astrophysics Data System (ADS)

    Sapriza-Azuri, G.; Gamazo, P. A.; Razavi, S.; Wheater, H. S.

    2016-12-01

    Earth system models are essential for the evaluation of the impact of climate change. At global and regional scales, General Circulation Models (GCM) and Regional Climate Models (RCM) are used to simulate climate change evolution. Hydrological Land Surface Models (HLSM) are used along with GCMs and RCMs (coupled or offline) to have a better representation of the hydrological cycle. All these models typically have a common implementation of the energy and water balance in the soil, known as the Land Surface Model (LSM). In general, a standard soil configuration with a depth of no more than 4 meters is used in all LSMs that are commonly implemented in GCMs, RCMs and HLSMs. For moderate climate conditions, this depth is sufficient to capture the intra-annual variability in the energy and water balance. However, for cold regions and for long-term simulations, deeper subsurface layers are needed in order to allow the heat signal to propagate through the soil to deeper layers and hence to avoid erroneous near-surface states and fluxes. Deeper soil/rock configurations create longer system memories, and as such, particular care should be taken to define the initial conditions for the subsurface system. In this work we perform a sensitivity analysis of the main factors that affect the subsurface energy and water balance for LSMs in cold regions - depth of soil, soil parameters, initial conditions and climate conditions for a warm-up period. We implement a 1D model using the Canadian Land Surface Scheme (CLASS) LSM for a study area in northern Canada where measurements of soil temperature profiles are available. Results suggest that an adequate representation of the heat propagation process in the soil requires the simulation of a soil depth of greater than 25 meters. As for initial conditions we recommend to spin-up over a cycle of an average climate year and then use reconstructed climate time series with a length of more than 300 years.

  5. Characterising soil surface roughness using a combined structural and spectral approach

    NASA Astrophysics Data System (ADS)

    Croft, H.; Anderson, K.; Kuhn, N. J.

    2009-04-01

    This paper describes the results of an experiment designed to investigate whether hyperspectral directional reflectance factors can be used to describe fine-scale variations in soil surface roughness. A Canadian silt loam soil was sieved to an aggregate size range of 1-4.75 mm and exposed to five different durations of artificial rainfall to produce soil states displaying progressively decreasing levels of surface roughness. Each soil state was measured using a point laser profiling instrument at 2 mm spatial resolution, in order to provide information on the surface structure and spatial arrangement of soil particles. Hyperspectral directional reflectance factors were measured using an Analytical Spectral Devices FieldSpec Pro instrument (range 350-2500 nm), with reference to a calibrated Spectralon panel. A broad range of measurement angles were used (θr = -60° to +60°) in the solar principal plane; with a wide range of illumination angle conditions (θi = 28° to 74°). Directional reflectance factors were found to vary with illumination and view angles, and according to the soil state. Geostatistically-derived indicators of soil surface roughness (sill variance) were then used as the basis for linear regression with directional reflectance factors. The results showed a strong relationship between directional reflectance factors and surface roughness (R2 = 0.94 where θr = -60°, θi = 67°-74°). This fine-scale quasi-natural experiment allowed the control of slope, initial aggregate size and rainfall exposure. This permitted an investigation into the nature of interaction between specific factors affecting the reflectance distribution; highlighting the importance in understanding fine-scale variations in surface roughness and particularly illumination angle. The results of the paper suggest that this technique could prove useful for providing a quantitative measure of surface roughness at fine spatial scales.

  6. The Role of Iron-Bearing Minerals in NO2 to HONO Conversion on Soil Surfaces.

    PubMed

    Kebede, Mulu A; Bish, David L; Losovyj, Yaroslav; Engelhard, Mark H; Raff, Jonathan D

    2016-08-16

    Nitrous acid (HONO) accumulates in the nocturnal boundary layer where it is an important source of daytime hydroxyl radicals. Although there is clear evidence for the involvement of heterogeneous reactions of NO2 on surfaces as a source of HONO, mechanisms remain poorly understood. We used coated-wall flow tube measurements of NO2 reactivity on environmentally relevant surfaces (Fe (hydr)oxides, clay minerals, and soil from Arizona and the Saharan Desert) and detailed mineralogical characterization of substrates to show that reduction of NO2 by Fe-bearing minerals in soil can be a more important source of HONO than the putative NO2 hydrolysis mechanism. The magnitude of NO2-to-HONO conversion depends on the amount of Fe(2+) present in substrates and soil surface acidity. Studies examining the dependence of HONO flux on substrate pH revealed that HONO is formed at soil pH < 5 from the reaction between NO2 and Fe(2+)(aq) present in thin films of water coating the surface, whereas in the range of pH 5-8 HONO stems from reaction of NO2 with structural iron or surface complexed Fe(2+) followed by protonation of nitrite via surface Fe-OH2(+) groups. Reduction of NO2 on ubiquitous Fe-bearing minerals in soil may explain HONO accumulation in the nocturnal boundary layer and the enhanced [HONO]/[NO2] ratios observed during dust storms in urban areas.

  7. Updated global soil map for the Weather Research and Forecasting model and soil moisture initialization for the Noah land surface model

    NASA Astrophysics Data System (ADS)

    DY, C. Y.; Fung, J. C. H.

    2016-08-01

    A meteorological model requires accurate initial conditions and boundary conditions to obtain realistic numerical weather predictions. The land surface controls the surface heat and moisture exchanges, which can be determined by the physical properties of the soil and soil state variables, subsequently exerting an effect on the boundary layer meteorology. The initial and boundary conditions of soil moisture are currently obtained via National Centers for Environmental Prediction FNL (Final) Operational Global Analysis data, which are collected operationally in 1° by 1° resolutions every 6 h. Another input to the model is the soil map generated by the Food and Agriculture Organization of the United Nations - United Nations Educational, Scientific and Cultural Organization (FAO-UNESCO) soil database, which combines several soil surveys from around the world. Both soil moisture from the FNL analysis data and the default soil map lack accuracy and feature coarse resolutions, particularly for certain areas of China. In this study, we update the global soil map with data from Beijing Normal University in 1 km by 1 km grids and propose an alternative method of soil moisture initialization. Simulations of the Weather Research and Forecasting model show that spinning-up the soil moisture improves near-surface temperature and relative humidity prediction using different types of soil moisture initialization. Explanations of that improvement and improvement of the planetary boundary layer height in performing process analysis are provided.

  8. Estimation of near-surface soil moisture based on MODIS data over Taklamakan's Oases - China

    NASA Astrophysics Data System (ADS)

    Badawy, Moawad; Meixner, Franz X.; Behrendt, Thomas; Mamtimin, Buhalqem

    2013-04-01

    Soil moisture is the most important factor that shapes the biotic and aboitic properties of the soil. Crop yielding is more often determined by the availability of soil moisture rather than deficiency of other nutrients. Hence, soil moisture management is imperative for sustainable food production and water supply; it also controls the response and feedback mechanisms between land surface and atmospheric processes and has been widely recognized in numerous environmental studies. However, spatially and temporally limited in-situ field observations are not appropriate to describe spatial variations of soil moisture over large areas. Consequently, there is a great need for satellite remote sensing to estimate and monitor the spatial and temporal variations of soil moisture. Recent advances in remote sensing have shown that soil moisture can be estimated by a variety of methods using visible bands (VIS), thermal infrared (TIR) and microwave imaging systems. Particularly optical remote sensing provides fine to moderate spatial resolution for near surface soil moisture estimation. In that context, MODIS data are a well-suited source for soil moisture estimation on a moderate-scale of spatial domain. The main objective of this work is to estimate the near-surface soil moisture (the "surface wetness") of some oases located in Taklamakan Desert (Xinjiang Uygur Autonomous Region, Northwest China) using MODIS data in combination with in-situ (field) observations. The Taklamakan Desert encloses many oases of different sizes, where key oases (watered by rainfall and irrigation) are Awati, Kuqa, and Turpan in the north, Milan, Ruoqiang, Waxxari, Qiemo, Minfeng, Yutian and Hotan in the south, and Shache in the west. This study uses the triangular (or trapezoid) method based on land surface temperature and vegetation index (Ts/VI) feature space. For the period 28 July to 29 August 2010, Ts and VI were derived from MODIS (day/night) land surface temperature (MOD11A2- 8 days) and

  9. Geospatial Analysis of Near-Surface Soil Moisture Time Series Data Over Indian Region

    NASA Astrophysics Data System (ADS)

    Berwal, P.; Murthy, C. S.; Raju, P. V.; Sesha Sai, M. V. R.

    2016-06-01

    The present study has developed the time series database surface soil moisture over India, for June, July and August months for the period of 20 years from 1991 to 2010, using data products generated under Climate Change Initiative Programme of European Space Agency. These three months represent the crop sowing period in the prime cropping season in the country and the soil moisture data during this period is highly useful to detect the drought conditions and assess the drought impact. The time series soil moisture data which is in 0.25 degree spatial resolution was analyzed to generate different indicators. Rainfall data of same spatial resolution for the same period, generated by India Meteorological Department was also procured and analyzed. Geospatial analysis of soil moisture and rainfall derived indicators was carried out to study (1) inter annual variability of soil moisture and rainfall, (2) soil moisture deviations from normal during prominent drought years, (3) soil moisture and rainfall correlations and (4) drought exposure based on soil moisture and rainfall variability. The study has successfully demonstrated the potential of these soil moisture time series data sets for generating regional drought surveillance information products, drought hazard mapping, drought exposure analysis and detection of drought sensitive areas in the crop planting period.

  10. Potential applications of surface active compounds by Gordonia sp. strain BS29 in soil remediation technologies.

    PubMed

    Franzetti, Andrea; Caredda, Paolo; Ruggeri, Claudio; La Colla, Paolo; Tamburini, Elena; Papacchini, Maddalena; Bestetti, Giuseppina

    2009-05-01

    A wide range of structurally different surface active compounds (SACs) is synthesised by many prokaryotic and eukaryotic microorganisms. Due to their properties, microbial SACs have been exploited in environmental remediation techniques. From a diesel-contaminated soil, we isolated the Gordonia sp. strain BS29 which extensively grows on aliphatic hydrocarbons and produces two different types of SACs: extracellular bioemulsans and cell-bound biosurfactants. The aim of this work was to evaluate the potential applications of the strain BS29 and its SACs in the following environmental technologies: bioremediation of soils contaminated by aliphatic and aromatic hydrocarbons, and washing of soils contaminated by crude oil, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Microcosm bioremediation experiments were carried out with soils contaminated by aliphatic hydrocarbons or PAHs, while batch soil washing experiments were carried out with soils contaminated by crude oil, PAHs or heavy metals. Bioremediation results showed that the BS29 bioemulsans are able to slightly enhance the biodegradation of recalcitrant branched hydrocarbons. On the other hand, we obtained the best results in soil washing of hydrocarbons. The BS29 bioemulsans effectively remove crude oil and PAHs from soil. Particularly, crude oil removal by BS29 bioemulsans is comparable to the rhamnolipid one in the same experimental conditions showing that the BS29 bioemulsans are promising washing agents for remediation of hydrocarbon-contaminated soils.

  11. Estimating Long Term Surface Soil Moisture in the GCIP Area From Satellite Microwave Observations

    NASA Technical Reports Server (NTRS)

    Owe, Manfred; deJeu, Vrije; VandeGriend, Adriaan A.

    2000-01-01

    Soil moisture is an important component of the water and energy balances of the Earth's surface. Furthermore, it has been identified as a parameter of significant potential for improving the accuracy of large-scale land surface-atmosphere interaction models. However, accurate estimates of surface soil moisture are often difficult to make, especially at large spatial scales. Soil moisture is a highly variable land surface parameter, and while point measurements are usually accurate, they are representative only of the immediate site which was sampled. Simple averaging of point values to obtain spatial means often leads to substantial errors. Since remotely sensed observations are already a spatially averaged or areally integrated value, they are ideally suited for measuring land surface parameters, and as such, are a logical input to regional or larger scale land process models. A nine-year database of surface soil moisture is being developed for the Central United States from satellite microwave observations. This region forms much of the GCIP study area, and contains most of the Mississippi, Rio Grande, and Red River drainages. Daytime and nighttime microwave brightness temperatures were observed at a frequency of 6.6 GHz, by the Scanning Multichannel Microwave Radiometer (SMMR), onboard the Nimbus 7 satellite. The life of the SMMR instrument spanned from Nov. 1978 to Aug. 1987. At 6.6 GHz, the instrument provided a spatial resolution of approximately 150 km, and an orbital frequency over any pixel-sized area of about 2 daytime and 2 nighttime passes per week. Ground measurements of surface soil moisture from various locations throughout the study area are used to calibrate the microwave observations. Because ground measurements are usually only single point values, and since the time of satellite coverage does not always coincide with the ground measurements, the soil moisture data were used to calibrate a regional water balance for the top 1, 5, and 10 cm

  12. Mapping drought and soil moisture with a thermal two-source surface flux model

    USDA-ARS?s Scientific Manuscript database

    The Two-Source (Soil+Canopy) Surface Energy Balance (TSEB) model of Norman et al. (1995) has proven to be a versatile and robust framework for mapping surface fluxes at multiple spatial scales using thermal remote sensing data. The TSEB has been coupled with an atmospheric boundary layer model in a...

  13. NOX AND CO EMISSIONS FROM SOIL AND SURFACE LITTER IN A BRAZILIAN SAVANNA

    EPA Science Inventory

    Land clearing and burning in the tropics often results in increased solar irradiation of soil and surface organic matter. This increased light exposure and surface heating may impact the emissions of nitrogen oxides (NOx) and carbon monoxide (CO), trace gases that play an importa...

  14. Effects of rainfall and surface flow on chemical diffusion from soil to runoff water

    USDA-ARS?s Scientific Manuscript database

    Although basic processes of diffusion and convection have been used to quantify chemical transport from soil to surface runoff, there are little research results actually showing how these processes were affected by rainfall and surface flow. We developed a laboratory flow cell and a sequence of exp...

  15. Estimation of Soil Moisture for Vegetated Surfaces Using Multi-Temporal L-Band SAR Measurements

    NASA Technical Reports Server (NTRS)

    Shi, Jian-Cheng; Sun, G.; Hsu, A.; Wang, J.; ONeill, P.; Ranson, J.; Engman, E. T.

    1997-01-01

    This paper demonstrates the technique to estimate ground surface and vegetation scattering components, based on the backscattering model and the radar decomposition theory, under configuration of multi-temporal L-band polarimetric SAR measurement. This technique can be used to estimate soil moisture of vegetated surface.

  16. NOX AND CO EMISSIONS FROM SOIL AND SURFACE LITTER IN A BRAZILIAN SAVANNA

    EPA Science Inventory

    Land clearing and burning in the tropics often results in increased solar irradiation of soil and surface organic matter. This increased light exposure and surface heating may impact the emissions of nitrogen oxides (NOx) and carbon monoxide (CO), trace gases that play an importa...

  17. Uptake of gaseous formaldehyde onto soil surfaces: a coated-wall flow tube study

    NASA Astrophysics Data System (ADS)

    Li, Guo; Su, Hang; Li, Xin; Meusel, Hannah; Kuhn, Uwe; Pöschl, Ulrich; Shao, Min; Cheng, Yafang

    2015-04-01

    Gaseous formaldehyde (HCHO) is an important intermediate molecule and source of HO2 radicals. However, discrepancies exist between model simulated and observed HCHO concentrations, suggesting missing sources or sinks in the HCHO budget. Multiphase processes on the surface of soil and airborne soil-derived particles have been suggested as an important mechanism for the production/removal of atmospheric trace gases and aerosols. In this work, the uptake of gaseous HCHO on soil surfaces were investigated through coated-wall flow tube experiments with HCHO concentration ranging from 10 to 40 ppbv. The results show that the adsorption of HCHO occurred on soil surfaces, and the uptake coefficient dropped gradually (i.e., by a factor of 5 after 1 hour) as the reactive surface sites were consumed. The HCHO uptake coefficient was found to be affected by the relative humidity (RH), decreasing from (2.4 ± 0.5) × 10-4 at 0% RH to (3.0 ± 0.08) × 10-5 at 70% RH, due to competition of water molecule absorption on the soil surface. A release of HCHO from reacted soil was also detected by applying zero air, suggesting the nature of reversible physical absorption and the existence of an equilibrium at the soil-gas interface. It implies that soil could be either a source or a sink for HCHO, depending on the ambient HCHO concentration. We also develop a Matlab program to calculate the uptake coefficient under laminar flow conditions based on the Cooney-Kim-Davis method.

  18. Spatial Distribution and Pattern Persistence of Surface Soil Moisture and Temperature Over Prairie from Remote Sensing

    NASA Technical Reports Server (NTRS)

    Chen, Daoyi; Engman, Edwin T.; Brutsaert, Wilfried

    1997-01-01

    Images remotely sensed aboard aircraft during FIFE, namely, PBMR (microwave) soil moisture and NS001 thermal infrared surface temperature, were mapped on the same coordinate system covering the 20 km x 20 km experimental site. For both kinds of image data, the frequency distributions were close to symmetric, and the area average compared reasonably well with the ground based measurements. For any image on any given day, the correlation between the remotely sensed values and collocated ground based measurements over the area was usually high in the case of NS001 surface temperature but low in the case of PBMR soil moisture. On the other hand, at any given flux station the correlation between the PBMR and gravimetric soil moisture over all available days was usually high. The correlation pixel by pixel between images of PBMR on different days was generally high. The preservation of the spatial patterns of soil moisture was also evaluated by considering the correlation station by station between ground-based soil moisture measurements on different days; no persistence of spatial pattern was apparent during wet periods, but a definite pattern gradually established itself toward the end of each drying episode. The spatial patterns of surface temperature revealed by NS001 were not preserved even within a single day. The cross-correlations among the two kinds of images and the vegetation index NDVI were normally poor. This suggests that different processes of vegetation growth, and of the near-surface soil water and energy budgets.

  19. Spatial Distribution and Pattern Persistence of Surface Soil Moisture and Temperature Over Prairie from Remote Sensing

    NASA Technical Reports Server (NTRS)

    Chen, Daoyi; Engman, Edwin T.; Brutsaert, Wilfried

    1997-01-01

    Images remotely sensed aboard aircraft during FIFE, namely, PBMR (microwave) soil moisture and NS001 thermal infrared surface temperature, were mapped on the same coordinate system covering the 20 km x 20 km experimental site. For both kinds of image data, the frequency distributions were close to symmetric, and the area average compared reasonably well with the ground based measurements. For any image on any given day, the correlation between the remotely sensed values and collocated ground based measurements over the area was usually high in the case of NS001 surface temperature but low in the case of PBMR soil moisture. On the other hand, at any given flux station the correlation between the PBMR and gravimetric soil moisture over all available days was usually high. The correlation pixel by pixel between images of PBMR on different days was generally high. The preservation of the spatial patterns of soil moisture was also evaluated by considering the correlation station by station between ground-based soil moisture measurements on different days; no persistence of spatial pattern was apparent during wet periods, but a definite pattern gradually established itself toward the end of each drying episode. The spatial patterns of surface temperature revealed by NS001 were not preserved even within a single day. The cross-correlations among the two kinds of images and the vegetation index NDVI were normally poor. This suggests that different processes of vegetation growth, and of the near-surface soil water and energy budgets.

  20. STIR Proposal For Research Area 2.1.2 Surface Energy Balance: Transient Soil Density Impacts Land Surface Characteristics and Characterization

    DTIC Science & Technology

    2015-12-22

    properties, and ii) evaluate impact of changing soil density on surface energy balance and heat and water transfer. Six soil properties were...2015 Approved for Public Release; Distribution Unlimited Final Report: STIR Proposal For Research Area 2.1.2 Surface Energy Balance : Transient Soil...surface energy balance REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER(S) 10. SPONSOR/MONITOR’S ACRONYM(S) ARO 8. PERFORMING

  1. The impact of subsurface physics on soil moisture estimates derived from the assimilation of surface observations

    NASA Astrophysics Data System (ADS)

    Reichle, R. H.; Kumar, S. V.; Koster, R. D.; Crow, W. T.; Peters-Lidard, C.

    2008-05-01

    Soil moisture controls the exchange of water and energy between the land surface and the atmosphere and exhibits memory that may be useful for climate prediction at monthly time scales. Large-scale observations of root zone soil moisture, however, are not routinely available. Assimilation of surface soil moisture observations (for example from satellites) into a land surface model (LSM) can yield improved estimates in the root zone. Land surface models, however, differ significantly in their representation of subsurface soil moisture processes. Therefore, the propagation of surface information into deeper soil layers depends on the LSM that is used in the assimilation system. Here, we use the Land Information System (LIS) data assimilation testbed, an interoperable framework for sequential data assimilation that enables the integrated use of multiple LSMs, observations types, and data assimilation algorithms. In a suite of experiments we assimilate synthetic surface soil moisture observations into four different LSMs (Catchment, Mosaic, Noah and CLM) using the Ensemble Kalman Filter and investigate the impact of subsurface physics on the skill of soil moisture assimilation products. Our results suggest that assimilation of surface soil moisture generally provides improvements in the root zone estimates. The magnitude of improvements in the root zone is highest if the true subsurface physics has a strong correlation between the surface and root zone, such as in the case of Catchment LSM, regardless of which LSM is used in the assimilation system. For northern-hemisphere summer conditions, we also find that the average skill improvements through data assimilation across different "truth" scenarios are comparable regardless of which model is used in the assimilation system. When evaluating year-round improvements, the use of CLM in the assimilation system yields more limited improvements than use of Catchment, Mosaic, or Noah. This suggests that a simpler LSM is a

  2. Fate and Disposition of Trichloroethylene in Surface Soils.

    DTIC Science & Technology

    1984-01-01

    Actinomycetes Fungi Algae Bacteria Bacteria 3-8 7,800 1,950 2,080 119 25 20-25 1,800 379 245 50 5 35-40 472 98 49 14 0.5... - 65-75 10 1 5 6 0.1 135-145 1 0.4...1) lists the five major groups of soil microorganisms as bacteria, actinomycetes , fungi, algae, and protozoa. Bacteria are the most prominent group

  3. Evaluation of Deterministic Models for Near Surface Soil Moisture Prediction

    DTIC Science & Technology

    1988-05-01

    probabilities for selected sites across Canada’, Agrometeorology Section. Research Branch. Agriculture Canada. Ottawa. Ontario. Technical Bulletin 86. i Dyer...J.A., (1980) ’Fall field workdays in Canada’, Agrometeorology Section. Research Branch, Agriculture Canada. Ottawa, Ontario, Technical Bulletin 92...Dyer, J.A. and A.R. Mack, (1984)’The versatile soil moisture budget - version three’, Agrometeorology Section. Research Branch. Agriculture Canada

  4. A quasi-global approach to improve day-time satellite surface soil moisture anomalies through land surface temperature input

    USDA-ARS?s Scientific Manuscript database

    Passive microwave observations from various space borne sensors have been linked to soil moisture of the Earth’s surface layer. The new generation passive microwave sensors are dedicated to retrieving this variable and make observations in the single, theoretically optimal L-band frequency (1-2 GHz)...

  5. Development of a land surface model with coupled snow and frozen soil physics

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhou, Jing; Qi, Jia; Sun, Litao; Yang, Kun; Tian, Lide; Lin, Yanluan; Liu, Wenbin; Shrestha, Maheswor; Xue, Yongkang; Koike, Toshio; Ma, Yaoming; Li, Xiuping; Chen, Yingying; Chen, Deliang; Piao, Shilong; Lu, Hui

    2017-06-01

    Snow and frozen soil are important factors that influence terrestrial water and energy balances through snowpack accumulation and melt and soil freeze-thaw. In this study, a new land surface model (LSM) with coupled snow and frozen soil physics was developed based on a hydrologically improved LSM (HydroSiB2). First, an energy-balance-based three-layer snow model was incorporated into HydroSiB2 (hereafter HydroSiB2-S) to provide an improved description of the internal processes of the snow pack. Second, a universal and simplified soil model was coupled with HydroSiB2-S to depict soil water freezing and thawing (hereafter HydroSiB2-SF). In order to avoid the instability caused by the uncertainty in estimating water phase changes, enthalpy was adopted as a prognostic variable instead of snow/soil temperature in the energy balance equation of the snow/frozen soil module. The newly developed models were then carefully evaluated at two typical sites of the Tibetan Plateau (TP) (one snow covered and the other snow free, both with underlying frozen soil). At the snow-covered site in northeastern TP (DY), HydroSiB2-SF demonstrated significant improvements over HydroSiB2-F (same as HydroSiB2-SF but using the original single-layer snow module of HydroSiB2), showing the importance of snow internal processes in three-layer snow parameterization. At the snow-free site in southwestern TP (Ngari), HydroSiB2-SF reasonably simulated soil water phase changes while HydroSiB2-S did not, indicating the crucial role of frozen soil parameterization in depicting the soil thermal and water dynamics. Finally, HydroSiB2-SF proved to be capable of simulating upward moisture fluxes toward the freezing front from the underlying soil layers in winter.

  6. Human Effects and Soil Surface CO2 fluxes in Tropical Urban Green Areas, Singapore

    NASA Astrophysics Data System (ADS)

    Ng, Bernard; Gandois, Laure; Kai, Fuu Ming; Chua, Amy; Cobb, Alex; Harvey, Charles; Hutyra, Lucy

    2013-04-01

    Urban green spaces are appreciated for their amenity value, with increasing interest in the ecosystem services they could provide (e.g. climate amelioration and increasingly as possible sites for carbon sequestration). In Singapore, turfgrass occupies approximately 20% of the total land area and is readily found on both planned and residual spaces. This project aims at understanding carbon fluxes in tropical urban green areas, including controls of soil environmental factors and the effect of urban management techniques. Given the large pool of potentially labile carbon, management regimes are recognised to have an influence on soil environmental factors (temperature and moisture), this would affect soil respiration and feedbacks to the greenhouse effect. A modified closed dynamic chamber method was employed to measure total soil respiration fluxes. In addition to soil respiration rates, environmental factors such as soil moisture and temperature, and ambient air temperature were monitored for the site in an attempt to evaluate their control on the observed fluxes. Measurements of soil-atmosphere CO2 exchanges are reported for four experimental plots within the Singtel-Kranji Radio Transmission Station (103o43'49E, 1o25'53N), an area dominated by Axonopus compressus. Different treatments such as the removal of turf, and application of clippings were effected as a means to determine the fluxes from the various components (respiration of soil and turf, and decomposition of clippings), and to explore the effects of human intervention on observed effluxes. The soil surface CO2 fluxes observed during the daylight hours ranges from 2.835 + 0.772 umol m-2 s-1 for the bare plot as compared to 6.654 + 1.134 umol m-2 s-1 for the turfed plot; this could be attributed to both autotrophic and heterotrophic respiration. Strong controls of both soil temperature and soil moisture are observed on measured soil fluxes. On the base soils, fluxes were positively correlated to soil

  7. A Comprehensive Laboratory Study to Improve Ground Truth Calibration of Remotely Sensed Near-Surface Soil Moisture

    NASA Astrophysics Data System (ADS)

    Babaeian, E.; Tuller, M.; Sadeghi, M.; Sheng, W.; Jones, S. B.

    2016-12-01

    Optical satellite and airborne remote sensing (RS) have been widely applied for characterization of large-scale surface soil moisture distributions. However, despite the excellent spatial resolution of RS data, the electromagnetic radiation within the optical bands (400-2500 nm) penetrates the soil profile only to a depth of a few millimeters; hence obtained moisture estimates are limited to the soil surface region. Furthermore, moisture sensor networks employed for ground truth calibration of RS observations commonly exhibit very limited spatial resolution, which consequently leads to significant discrepancies between RS and ground truth observations. To better understand the relationship between surface and near-surface soil moisture, we employed a benchtop hyperspectral line-scan imaging system to generate high resolution surface reflectance maps during evaporation from soil columns filled with source soils covering a wide textural range and instrumented with a novel time domain reflectometry (TDR) sensor array that allows monitoring of near surface moisture at 0.5-cm resolution. A recently developed physical model for surface soil moisture predictions from shortwave infrared reflectance was applied to estimate surface soil moisture from surface reflectance and to explore the relationship between surface and near-surface moisture distributions during soil drying. Preliminary results are very promising and their applicability for ground truth calibration of RS observations will be discussed.

  8. The lunar surface-exosphere connection: Measurement of secondary-ions from Apollo soils

    NASA Astrophysics Data System (ADS)

    Dukes, C. A.; Baragiola, R. A.

    2015-07-01

    Low energy secondary ions ejected by the solar wind are an important component of tenuous exospheres surrounding airless bodies, since these ions carry information on the planetary surface composition. In this work we examine the dependence of secondary-ion abundance, as a function of energy and mass, on surface composition. The surface compositions of two Apollo soils (10084 and 62231) and a synthetic Corning glass lunar simulant were measured with X-ray photoelectron spectroscopy and correlated with the spectra of secondary-ions ejected from the same soils by 4 keV He ions. XPS spectra for lunar soils show that the surface compositions are similar to the bulk, but enriched in Fe and O, while depleted in Mg and Ca. 4 keV He irradiation on the lunar soils and a glass simulant preferentially removes O and Si, enriching the surface in Al, Ti, Mg, and Ca. Secondary-ion species ejected from the Apollo soils by 4 keV He include: Na+, Mg+, Al+, Si+, Ca+, Ca++, Ti+, Fe+, and molecular species: NaO+, MgO+ and SiO+. Secondary ion energy distributions for lunar soil 10084 and 62231 rise rapidly, reach a maxima at ∼5 eV for molecular ions and Na+, ∼7.5 eV for Fe+, and ∼10 eV for Mg+, Al+, Si+, Ca+ and Ti+, then decrease slowly with energy. We present species-dependent relative conversion factors for the derivation of atomic surface composition from secondary-ion count rates for 4 keV He irradiation of lunar soils 10084 and 62231, as well as the Corning glass lunar simulant.

  9. Patterns and scaling properties of surface soil moisture in an agricultural landscape: An ecohydrological modeling study

    NASA Astrophysics Data System (ADS)

    Korres, W.; Reichenau, T. G.; Schneider, K.

    2013-08-01

    Soil moisture is a key variable in hydrology, meteorology and agriculture. Soil moisture, and surface soil moisture in particular, is highly variable in space and time. Its spatial and temporal patterns in agricultural landscapes are affected by multiple natural (precipitation, soil, topography, etc.) and agro-economic (soil management, fertilization, etc.) factors, making it difficult to identify unequivocal cause and effect relationships between soil moisture and its driving variables. The goal of this study is to characterize and analyze the spatial and temporal patterns of surface soil moisture (top 20 cm) in an intensively used agricultural landscape (1100 km2 northern part of the Rur catchment, Western Germany) and to determine the dominant factors and underlying processes controlling these patterns. A second goal is to analyze the scaling behavior of surface soil moisture patterns in order to investigate how spatial scale affects spatial patterns. To achieve these goals, a dynamically coupled, process-based and spatially distributed ecohydrological model was used to analyze the key processes as well as their interactions and feedbacks. The model was validated for two growing seasons for the three main crops in the investigation area: Winter wheat, sugar beet, and maize. This yielded RMSE values for surface soil moisture between 1.8 and 7.8 vol.% and average RMSE values for all three crops of 0.27 kg m-2 for total aboveground biomass and 0.93 for green LAI. Large deviations of measured and modeled soil moisture can be explained by a change of the infiltration properties towards the end of the growing season, especially in maize fields. The validated model was used to generate daily surface soil moisture maps, serving as a basis for an autocorrelation analysis of spatial patterns and scale. Outside of the growing season, surface soil moisture patterns at all spatial scales depend mainly upon soil properties. Within the main growing season, larger scale

  10. Preliminary results on soil-emitted gamma radiation and its relation with the local atmospheric electric field at Amieira (Portugal)

    NASA Astrophysics Data System (ADS)

    Lopes, F.; Silva, H. G.; Bárias, S.; Barbosa, S. M.

    2015-10-01

    The atmospheric electric field near the Earth's surface is dominated by atmospheric pollutants and natural radioactivity, with the latter directly linked to radon (222Rn) gas. For a better comprehension on the temporal variability of both the atmospheric electric field and the radon concentration and its relation with local atmospheric variables, simultaneous measurements of soil-emitted gamma radiation and potential gradient (defined from the vertical component of the atmospheric electric field) were taken every minute, along with local meteorological parameters (e.g., temperature, atmospheric pressure, relative humidity and daily solar radiation). The study region is Amieira, part of the Alqueva lake in Alentejo Portugal, where an interdisciplinary meteorological campaign, ALEX2014, took place from June to August 2014. Soil gamma radiation is more sensitive to small concentrations of radon as compared with alpha particles measurements, for that reason it is more suited for sites with low radon levels, as expected in this case. Preliminary results are presented here: statistical and spectral analysis show that i) the potential gradient has a stronger daily cycle as compared with the gamma radiation, ii) most of the energy of the gamma signal is concentrated in the low frequencies (close to 0), contrary to the potential gradient that has most of the energy in frequency 1 (daily cycle) and iii) a short-term relation between gamma radiation and the potential gradient has not been found. Future work and plans are also discussed.

  11. Concentrations and geographic distribution of selected organic pollutants in Scottish surface soils.

    PubMed

    Rhind, S M; Kyle, C E; Kerr, C; Osprey, M; Zhang, Z L; Duff, E I; Lilly, A; Nolan, A; Hudson, G; Towers, W; Bell, J; Coull, M; McKenzie, C

    2013-11-01

    Concentrations of selected persistent organic pollutants (POPs) representing three chemical classes (polycyclic aromatic hydrocarbons (PAH), polybrominated diphenyl ethers (PBDE) and polychlorinated biphenyls (PCB) and the organic pollutant diethylhexyl phthalate (DEHP), were determined in surface soil samples (0-5 cm) collected at 20 km grid intersects throughout Scotland over a three-year period. Detectable amounts of all chemical classes and most individual congeners were present in all samples. There were no consistent effects of soil or vegetation type, soil carbon content, pH, altitude or distance from centres of population on concentrations which exhibited extreme variation, even in adjacent samples. It is concluded that soil POPs and DEHP concentrations and associated rates of animal and human exposure were highly variable, influenced by multiple, interacting factors, and not clearly related to local sources but possibly related to wet atmospheric deposition and the organic carbon content of the soil. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Study on ozone treatment of soil for agricultural application of surface dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Nagatomo, Takuya; Abiru, Tomoya; Mitsugi, Fumiaki; Ebihara, Kenji; Nagahama, Kazuhiro

    2016-01-01

    Recently, application of plasma technologies to the agricultural field has attracted much interest because residual pesticides and excessive nitrogen oxides contained in plants, soil, and groundwater have become a serious issue worldwide. Since almost all of the atmospheric discharge plasma generates ozone, the effects of ozone are among the key factors for their agricultural applications. We have proposed the use of ozone generated using surface barrier discharge plasma for soil disinfection or sterilization. In this work, the ozone consumption coefficient and diffusion coefficient in soil were measured by the ultraviolet absorption method. The pH(H2O) and amount of nitrogen nutrient in soil after ozone diffusion treatment were studied and plant growth was observed simultaneously. The effect of ozone treatment on the amount of DNA in soil was also investigated and compared with that determined from the obtained ozone consumption coefficient.

  13. Surface soil as a potential source of lead exposure for young children.

    PubMed Central

    Schmitt, N; Philion, J J; Larsen, A A; Harnadek, M; Lynch, A J

    1979-01-01

    Soil analyses revealed an elevated lead content in the surface soil of three British Columbia cities. The lead accumulations were largely attributed to dustfall from a nearby large lead-zinc smelter in Trail and to automotive traffic in Nelson and Vancouver. Although the mean concentrations of lead in the soil were relatively low at Nelson (192 parts per million [ppm]), in selected areas of Vancouver with heavy traffic they were similar to those found within 1.6 km of the large smelter at Trail (1545 and 1662 ppm respectively). In a study conducted in 1975, children aged 1 to 6 years in Trail and Nelson were found to have higher mean blood lead levels than grade nine students. The findings of the later study support the view that particulate lead in surface soil and dust accounted for most of the greater lead absorption in the younger children. PMID:519574

  14. [Distribution Characteristics and Source Identification of Organochlorine Pesticides in Surface Soil in Karst Underground River Basin].

    PubMed

    Xie, Zheng-lan; Sun, Yu-chuan; Zhang, Mei; Yu, Qin; Xu, Xin

    2016-03-15

    Six typical surface soil samples were taken in Laolongdong underground river basin, and 20 OCPs were analyzed by gas chromatography equipped with micro-⁶³Ni electron capture detector. The purpose of this study was to investigate the distribution, composition and source of organochlorine pesticides ( OCPs) in the surface soil of Laolongdong underground river basin, and to further evaluate the pollution level. The results showed that 20 OCPs were inordinately detected in the soil samples and the detection rate of 16 OCPs (except for p,p'-DDE, cis-Chlordane, trans-Chlordane, dieldrin) was 100%. Moreover, the CHLs and DDTs were the main contaminants, and there were obvious differences in the concentrations of organochlorine pesticides between different sampling points. The concentration range of total OCPs was 5.57-2,618.57 ng · g⁻¹ with a mean of 467.28 ng · g⁻¹. Compared with other regions both at home and abroad, the concentrations of HCHs and DDTs in the surface soil samples of the studied area were arranged from high to middle levels. The total concentrations of OCPs, HCHs, DDTs and CHLs had a similar variation tendency in spatial distribution, upstream > midstream > downstream, and the concentrations of OCPs in upstream were obviously higher than those in midstream and downstream. Source analysis indicated that the HCHs mainly came from the use of lindane. DDTs in soil came from not only the early residues but also recently illegal use of industrial DDTs and the input of dicofol. In addition, chlordan was mainly from the early residues and atmospheric deposition. Compared with the Environmental Quality Standard for Soils of China and Netherlands, the level of OCPs in Xinli vilage soil was categorized as highly polluted, but the levels of OCPs in Longjing bay, Xia spit, and Zhao courtyard soils were classified as slightly polluted, while the Longjing adjacency and gaozhong temple soils belonged to unpolluted ones.

  15. Phosphorus Speciation of Forest-soil Organic Surface Layers using P K-edge XANES Spectroscopy

    SciTech Connect

    J Prietzel; J Thieme; D Paterson

    2011-12-31

    The phosphorus (P) speciation of organic surface layers from two adjacent German forest soils with different degree of water-logging (Stagnosol, Rheic Histosol) was analyzed by P K-edge XANES and subsequent Linear Combination Fitting. In both soils, {approx}70% of the P was inorganic phosphate and {approx}30% organic phosphate; reduced P forms such as phosphonate were absent. The increased degree of water-logging in the Histosol compared to the Stagnosol did not affect P speciation.

  16. Soil Moisture-Atmosphere Feedbacks on Atmospheric Tracers: The Effects of Soil Moisture on Precipitation and Near-Surface Chemistry

    NASA Astrophysics Data System (ADS)

    Tawfik, Ahmed B.

    The atmospheric component is described by rapid fluctuations in typical state variables, such as temperature and water vapor, on timescales of hours to days and the land component evolves on daily to yearly timescales. This dissertation examines the connection between soil moisture and atmospheric tracers under varying degrees of soil moisture-atmosphere coupling. Land-atmosphere coupling is defined over the United States using a regional climate model. A newly examined soil moisture-precipitation feedback is identified for winter months extending the previous summer feedback to colder temperature climates. This feedback is driven by the freezing and thawing of soil moisture, leading to coupled land-atmosphere conditions near the freezing line. Soil moisture can also affect the composition of the troposphere through modifying biogenic emissions of isoprene (C5H8). A novel first-order Taylor series decomposition indicates that isoprene emissions are jointly driven by temperature and soil moisture in models. These compounds are important precursors for ozone formation, an air pollutant and a short-lived forcing agent for climate. A mechanistic description of commonly observed relationships between ground-level ozone and meteorology is presented using the concept of soil moisture-temperature coupling regimes. The extent of surface drying was found to be a better predictor of ozone concentrations than temperature or humidity for the Eastern U.S. This relationship is evaluated in a coupled regional chemistry-climate model under several land-atmosphere coupling and isoprene emissions cases. The coupled chemistry-climate model can reproduce the observed soil moisture-temperature coupling pattern, yet modeled ozone is insensitive to changes in meteorology due to the balance between isoprene and the primary atmospheric oxidant, the hydroxyl radical (OH). Overall, this work highlights the importance of soil moisture-atmosphere coupling for previously neglected cold climate

  17. Estimating the amount and distribution of radon flux density from the soil surface in China.

    PubMed

    Zhuo, Weihai; Guo, Qiuju; Chen, Bo; Cheng, Guan

    2008-07-01

    Based on an idealized model, both the annual and the seasonal radon ((222)Rn) flux densities from the soil surface at 1099 sites in China were estimated by linking a database of soil (226)Ra content and a global ecosystems database. Digital maps of the (222)Rn flux density in China were constructed in a spatial resolution of 25 km x 25 km by interpolation among the estimated data. An area-weighted annual average (222)Rn flux density from the soil surface across China was estimated to be 29.7+/-9.4 mBq m(-2)s(-1). Both regional and seasonal variations in the (222)Rn flux densities are significant in China. Annual average flux densities in the southeastern and northwestern China are generally higher than those in other regions of China, because of high soil (226)Ra content in the southeastern area and high soil aridity in the northwestern one. The seasonal average flux density is generally higher in summer/spring than winter, since relatively higher soil temperature and lower soil water saturation in summer/spring than other seasons are common in China.

  18. Concentration and Spatial Distribution of Polycyclic Aromatic Hydrocarbons in Surface Roadside Soils, Shanghai

    NASA Astrophysics Data System (ADS)

    Pan, Zhaoyu; Liu, Ying; He, Yao; Chen, Ling

    2010-11-01

    Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants that may lead to mutagenesis, carcinogenesis or teratogenesis. Vehicular traffic pollution is one of the important sources for PAHs in soils. Concentrations of 19 PAHs were detected in soils along nine roads in Shanghai by automatic Soxhlet extraction and high performance liquid chromatography. Concentration and spatial distribution of PAHs in surface soils beside nine target roads in Shanghai were investigated and a preliminary migration regularity of PAHs was proposed based on data analysis of Cheting Highway (NO.320 Chinese National Highway). The result showed that the total concentrations of PAHs in the target roadside soils ranged from undetectable to 34.6μg/g-dw, with a mean of 7.77μg/g-dw. In comparison with the level of PAHs in urban or suburban roadside soils, the results showed significantly that Σ PAHs concentration in roadside soils inside industrial areas was higher. The study on the migration regularity of PAHs in soils along roads demonstrated that surface runoff had a more significant effect on the PAHs transportation than air-borne transportation.

  19. Optimal averaging of soil moisture predictions from ensemble land surface model simulations

    NASA Astrophysics Data System (ADS)

    Crow, Wade T.; Su, Chun-Hsu; Ryu, Dongryeol; Tugrul Yilmaz, M.

    2015-04-01

    The correct interpretation of ensemble 3 soil moisture information obtained from the parallel implementation of multiple land surface models (LSMs) requires information concerning the LSM ensemble's mutual error covariance. Here we propose a new technique for obtaining such information using an instrumental variable (IV) regression approach and comparisons against a long-term surface soil moisture dataset obtained from satellite remote sensing. Application of the approach to multi-model ensemble soil moisture output from the North American Land Data Assimilation System (NLDAS-2), and multi-satellite European Space Agency (ESA) Soil Moisture (SM) Essential Climate Variable (ECV) dataset, allows for the calculation of optimal weighting coefficients for individual members of a the NLDAS-2 ensemble and a biased-minimized estimate of uncertainty in a deterministic soil moisture analysis derived via such optimal weighted averaging. As such, it provides key information required to accurately condition soil moisture expectations using information gleaned from a multi-model LSM ensemble. However, existing continuity and rescaling concerns surrounding the generation of long-term, satellite-based soil moisture products must likely be resolved before the proposed approach can be applied with full confidence.

  20. Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

    1998-01-01

    Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from <20 pm size factions (dry-sieved) of mature lunar soils. It has been demonstrated that it is the finest size fraction (<25 pm) of lunar soils that dominates the optical properties of the bulk soils.

  1. Surface-Correlated Nanophase Iron Metal in Lunar Soils: Petrography and Space Weathering Effects

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.; Wentworth, Susan J.; McKay, David S.

    1998-01-01

    Space weathering is a term used to include all of the processes that act on material exposed at the surface of a planetary or small body. In the case of the Moon, it includes a variety of processes that formed the lunar regolith, caused the maturation of lunar soils, and formed patina on rock surfaces. The processes include micrometeorite impact and reworking, implantation of solar wind and flare particles, radiation damage and chemical effects from solar particles and cosmic rays, interactions with the lunar atmosphere, and sputtering erosion and deposition. Space weathering effects collectively result in a reddened continuum slope, lowered albedo, and attenuated absorption features in reflectance spectra of lunar soils as compared to finely comminuted rocks from the same Apollo sites. Understanding these effects is critical in order to fully integrate the lunar sample collection with remotely sensed data from recent robotic missions (e.g., Lunar Prospector, Clementine, Galileo). Our objective is to determine the origin of space weathering effects in lunar soils through combined electron microscopy and microspectrophotometry techniques applied to individual soil particles from <20 pm size factions (dry-sieved) of mature lunar soils. It has been demonstrated that it is the finest size fraction (<25 pm) of lunar soils that dominates the optical properties of the bulk soils.

  2. Vapor Deposition and Solar Wind Implantation on Lunar Soil-Grain Surfaces as Comparable Processes

    NASA Technical Reports Server (NTRS)

    Basu, A.; Wentworth, S. J.; McKay, D. S.

    2004-01-01

    Vapor deposited patinas (VDP) on lunar soil grains consist of a thin (less than 1 micron) layer of amorphous silicate (glass) embedded with nanoscale Fe(sup 0) globules as seen in many TEM images. VDPs are also present on larger space-weathered lunar rocks; these larger samples will not be discussed here although the process of vapor deposition is common to exposed grains of all sizes. Whether or not the majority of the Fe(sup 0) globules present in lunar soils reside in vapor deposited patina is a matter of some concern. Some Fe(sup 0) globules are clearly seen to reside within the glass of agglutinates and might represent remobilized Fe(sup 0) in agglutinitic melts. remobilized Fe(sup 0) in agglutinitic melts. We argue that because VDP coatings are present only on the surfaces of lunar soil grains, their distribution as a surface correlated component (SCC) of lunar soils should parallel those of Solar Wind Elements (SWE) implanted in the outermost rinds of lunar soil grains. SWE residing in the interior of soils grains make up the volume correlated component (VCC). Relative to Fe(sup 0) in VDP, the distribution of various SWE have been studied well. The reason is understandable because instrumentation for nanoscale imaging is not ubiquitous. In this study we use the distribution of SWE in lunar soils as a guide to understanding the fate of Fe(sup 0) in VDP.

  3. Impact of Soil Moisture Assimilation on Land Surface Model Spinup and Coupled Land-Atmosphere Prediction

    NASA Astrophysics Data System (ADS)

    Santanello, J. A., Jr.; Kumar, S.; Peters-Lidard, C. D.; Lawston, P.

    2015-12-01

    Advances in satellite monitoring of the terrestrial water cycle have led to a concerted effort to assimilate soil moisture observations from various platforms into offline land surface models (LSMs). One principal but still open question is that of the ability of land data assimilation (LDA) to improve LSM initial conditions for coupled short-term weather prediction. In this study, the impact of assimilating Advanced Microwave Scanning Radiometer for EOS (AMSR-E) soil moisture retrievals on coupled WRF forecasts is examined during the summers of dry (2006) and wet (2007) surface conditions in the U.S. Southern Great Plains. LDA is carried out using NASA's Land Information System (LIS) and the Noah LSM using an Ensemble Kalman Filter (EnKF) approach. The impacts of LDA on the a) soil moisture and soil temperature initial conditions for WRF, b) land-atmosphere coupling characteristics, and c) ambient weather of the coupled LIS-WRF simulations are then assessed. Results show that impacts of soil moisture LDA during the spinup can significantly modify LSM states and fluxes, depending on regime and season. Results also quantify the impacts of using seasonal versus cumulative CDF matching and coarse vs. fine-scale atmospheric forcing approaches. Downstream impacts on coupled simulations vary according to the strength of the LDA impact at initialization, and significant modification to the soil moisture-flux-PBL-ambient weather process chain are observed. Overall, improvements due to LDA in this study show promise for future soil moisture assimilation applications in weather and climate.

  4. A one-dimensional interactive soil-atmosphere model for testing formulations of surface hydrology

    NASA Technical Reports Server (NTRS)

    Koster, Randal D.; Eagleson, Peter S.

    1990-01-01

    A model representing a soil-atmosphere column in a GCM is developed for off-line testing of GCM soil hydrology parameterizations. Repeating three representative GCM sensitivity experiments with this one-dimensional model demonstrates that, to first order, the model reproduces a GCM's sensitivity to imposed changes in parameterization and therefore captures the essential physics of the GCM. The experiments also show that by allowing feedback between the soil and atmosphere, the model improves on off-line tests that rely on prescribed precipitation, radiation, and other surface forcing.

  5. Moment Analysis Characterizing Water Flow in Repellent Soils from On- and Sub-Surface Point Sources

    NASA Astrophysics Data System (ADS)

    Xiong, Yunwu; Furman, Alex; Wallach, Rony

    2010-05-01

    Water repellency has a significant impact on water flow patterns in the soil profile. Flow tends to become unstable in such soils, which affects the water availability to plants and subsurface hydrology. In this paper, water flow in repellent soils was experimentally studied using the light reflection method. The transient 2D moisture profiles were monitored by CCD camera for tested soils packed in a transparent flow chamber. Water infiltration experiments and subsequent redistribution from on-surface and subsurface point sources with different flow rates were conducted for two soils of different repellency degrees as well as for wettable soil. We used spatio-statistical analysis (moments) to characterize the flow patterns. The zeroth moment is related to the total volume of water inside the moisture plume, and the first and second moments are affinitive to the center of mass and spatial variances of the moisture plume, respectively. The experimental results demonstrate that both the general shape and size of the wetting plume and the moisture distribution within the plume for the repellent soils are significantly different from that for the wettable soil. The wetting plume of the repellent soils is smaller, narrower, and longer (finger-like) than that of the wettable soil compared with that for the wettable soil that tended to roundness. Compared to the wettable soil, where the soil water content decreases radially from the source, moisture content for the water-repellent soils is higher, relatively uniform horizontally and gradually increases with depth (saturation overshoot), indicating that flow tends to become unstable. Ellipses, defined around the mass center and whose semi-axes represented a particular number of spatial variances, were successfully used to simulate the spatial and temporal variation of the moisture distribution in the soil profiles. Cumulative probability functions were defined for the water enclosed in these ellipses. Practically identical

  6. Bacteria increase arid-land soil surface temperature through the production of sunscreens

    DOE PAGES

    Couradeau, Estelle; Karaoz, Ulas; Lim, Hsiao Chien; ...

    2016-01-20

    Soil surface temperature, an important driver of terrestrial biogeochemical processes, depends strongly on soil albedo, which can be significantly modified by factors such as plant cover. In sparsely vegetated lands, the soil surface can be colonized by photosynthetic microbes that build biocrust communities. Here we use concurrent physical, biochemical and microbiological analyses to show that mature biocrusts can increase surface soil temperature by as much as 10 °C through the accumulation of large quantities of a secondary metabolite, the microbial sunscreen scytonemin, produced by a group of late-successional cyanobacteria. Scytonemin accumulation decreases soil albedo significantly. Such localized warming has apparentmore » and immediate consequences for the soil microbiome, inducing the replacement of thermosensitive bacterial species with more thermotolerant forms. In conclusion, these results reveal that not only vegetation but also microorganisms are a factor in modifying terrestrial albedo, potentially impacting biosphere feedbacks on past and future climate, and call for a direct assessment of such effects at larger scales.« less

  7. Effects of Regional Topography and Spacecraft Observation Geometry on Surface Soil Moisture Estimation Accuracies

    NASA Astrophysics Data System (ADS)

    Moghaddam, M.; Akbar, R.; West, R. D.; Colliander, A.; Kim, S.; Dunbar, R. S.

    2015-12-01

    The NASA Soil Moisture Active-Passive Mission (SMAP), launched in January 2015, provides near-daily global surface soil moisture estimates via combined Active Radar and Passive Radiometer observations at various spatial resolutions. The goal of this mission is to enhance our understanding of global carbon and water cycles. This presentation will focus on a comprehensive assessment of the SMAP high resolution radar backscatter data (formally the L1C_S0_HiRes data product) obtained over a 3 km Woody Savanna region in north-central California during a 2.5 month period starting late May 2015. The effects of spacecraft observation geometry (fore- and aft-looks as well as ascending and descending obits) along with regional topography on soil moisture estimation abilities will be examined. Furthermore surface soil moisture retrievals, obtained through utilization of different combinations of observation geometries, will be compared to an existing network of in situsensors. Current electromagnetic scattering and emission models do not properly account for surface topography, therefore physical forward model predictions and observations have unaccounted mismatch errors which also affect soil moisture estimation accuracies. The goal of this study is to quantify these soil moisture prediction errors and highlight the need for new and complete Electromagnetic modeling efforts.

  8. The effect of surface sealing on soil moisture dynamics in a semiarid hillslope

    NASA Astrophysics Data System (ADS)

    Sela, S.; Svoray, T.; Assouline, S.

    2010-12-01

    Understanding the mechanisms underlying hillslope soil moisture dynamics and vegetation patchiness remains a current challenge in hydrology, especially in ungauged watersheds. In dry areas, these mechanisms include the formation of surface seals, that although directly affects infiltration and evaporation fluxes, researchers usually disregard its development when predicting soil moisture patterns. The role of these seals in shaping spatial and temporal patterns of soil moisture, considered as the primary limiting factor for dry area plant distribution, is still an open research gap. At the LTER Lehavim site, in the center of Israel (31020' N, 34045' E), a typical hillslope (0.115 Km2) was chosen offering different aspects and a classic geomorphologic banding. Annual rainfall is 290 mm, the soils are brown lithosols and arid brown loess and the dominant rock formations are Eocenean limestone and chalk with patches of calcrete. The vegetation is characterised by scattered dwarf shrubs (dominant species Sarcopoterium spinosum) and patches of herbaceous vegetation, mostly annuals, are spread between rocks and dwarf shrubs. An extensive spatial database of soil hydraulic and environmental parameters (e.g. slope, radiation, bulk density) was measured in the field and was interpolated to continuous maps using geostatistical techniques and physically-based models. To explore the effect of soil surface sealing, the Mualem and Assouline (1989) equations, describing the change in hydraulic parameters resulting from soil seal formation, were applied explicitly in space to the entire hillslope. Two simple indices were developed to describe local evaporation rates and the contribution of water from rock outcrops to the downslope soil patches. This spatio-temporal database was used to characterise 1187 cells serving as an input to a numeric model (Hydrus 1D) solving the flow equations to predict soil water content at the single storm and the seasonal scales. Predictions were

  9. Assimilation of SMOS Brightness Temperatures or Soil Moisture Retrievals into a Land Surface Model

    NASA Technical Reports Server (NTRS)

    De Lannoy, Gabrielle J. M.; Reichle, Rolf H.

    2016-01-01

    Three different data products from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated separately into the Goddard Earth Observing System Model, version 5 (GEOS-5) to improve estimates of surface and root-zone soil moisture. The first product consists of multi-angle, dual-polarization brightness temperature (Tb) observations at the bottom of the atmosphere extracted from Level 1 data. The second product is a derived SMOS Tb product that mimics the data at a 40 degree incidence angle from the Soil Moisture Active Passive (SMAP) mission. The third product is the operational SMOS Level 2 surface soil moisture (SM) retrieval product. The assimilation system uses a spatially distributed ensemble Kalman filter (EnKF) with seasonally varying climatological bias mitigation for Tb assimilation, whereas a time-invariant cumulative density function matching is used for SM retrieval assimilation. All assimilation experiments improve the soil moisture estimates compared to model-only simulations in terms of unbiased root-mean-square differences and anomaly correlations during the period from 1 July 2010 to 1 May 2015 and for 187 sites across the US. Especially in areas where the satellite data are most sensitive to surface soil moisture, large skill improvements (e.g., an increase in the anomaly correlation by 0.1) are found in the surface soil moisture. The domain-average surface and root-zone skill metrics are similar among the various assimilation experiments, but large differences in skill are found locally. The observation-minus-forecast residuals and analysis increments reveal large differences in how the observations add value in the Tb and SM retrieval assimilation systems. The distinct patterns of these diagnostics in the two systems reflect observation and model errors patterns that are not well captured in the assigned EnKF error parameters. Consequently, a localized optimization of the EnKF error parameters is needed to further improve Tb or SM retrieval

  10. Spatial distributions of 137Cs in surface soil in Jing-Jin-Ji Region, North China.

    PubMed

    Zhao, Ye; Yan, Dong; Zhang, Qing; Zhan, Jinyan; Hu, Hongxia

    2012-11-01

    Artificial Radiocaesium ((137)Cs) has been widely deposited over global soils. In this study, we measured (137)Cs activity concentrations in the soil samples taken from Jing-Jin-Ji Region, North China, during 2007-2008. The surface soil (0-20 cm) samples were collected from 452 sites in this region. The activity concentration of (137)Cs in the samples was measured using a GEM series HPGe (high-purity germanium) coaxial detector system (ADCOM-100). The main findings are as following. (1) The activity concentration of (137)Cs in surface soils in the region of study fluctuates within 0.3±0.1 to 12.9±0.4 Bq/kg with mean value of 3.7 Bq/kg. Compared to other regions located at roughly the same latitude, the (137)Cs activity is relatively low. The results indicate that there are no new inputs of the radionuclides into the area at that time and the data obtained could serve as baseline levels of (137)Cs in Jing-Jin-Ji Region. (2) Considering land use types, surface soil in woodland mostly shows high (137)Cs activities with rare natural erosion and anthropogenic activities, and the surface soil with relatively low (137)Cs activities appears in the areas of intensive anthropogenic activities, especially in the cities, river banks, reservoirs and the strongly eroded areas. The findings suggest that the varying distribution of (137)Cs activities in surface soil corresponds with land use types. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Volatilization of pesticides from the bare soil surface: evaluation of the humidity effect.

    PubMed

    Schneider, Martina; Endo, Satoshi; Goss, Kai-Uwe

    2013-01-01

    Volatilization of pesticides from soils under dry conditions (water content below the permanent wilting point) can be significantly influenced by sorption to hydrated mineral surfaces. This sorption process strongly depends on the water activity, expressed as equilibrium relative humidity in the pore space of the soil, and on the available surface area of the hydrated minerals. In this study, the influence of different humidity regimes on the volatilization of two pesticides (triallate and trifluralin) was demonstrated with a bench-scale wind tunnel system that allowed the establishment of well controlled humidity conditions within the soil. In the experiment starting with very dry conditions, increasing the relative humidity in the adjacent air from 60 to 85% resulted in an up to 8 times higher volatilization rate of the pesticides. An additional strong increase in volatilization (up to 3 times higher) was caused by a simulated rain event, which eliminates all sorption sites associated to mineral surfaces. In agreement with this interpretation, the comparison of two soils suggested that mineral surface area was the soil property that governs the volatilization under dry conditions, whereas soil organic matter was the controlling variable under wet conditions. In contrast to expectations, the use of a novel capsulated suspension for triallate showed the same humidity effects and no substantially lower volatilization rates in comparison to the regular formulation. This study demonstrated that humidity effects on pesticide volatilization can be interpreted via the mechanism of sorption to mineral surfaces under dry conditions. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  12. Assimilation of SMOS brightness temperatures or soil moisture retrievals into a land surface model

    NASA Astrophysics Data System (ADS)

    De Lannoy, Gabriëlle J. M.; Reichle, Rolf H.

    2016-12-01

    Three different data products from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated separately into the Goddard Earth Observing System Model, version 5 (GEOS-5) to improve estimates of surface and root-zone soil moisture. The first product consists of multi-angle, dual-polarization brightness temperature (Tb) observations at the bottom of the atmosphere extracted from Level 1 data. The second product is a derived SMOS Tb product that mimics the data at a 40° incidence angle from the Soil Moisture Active Passive (SMAP) mission. The third product is the operational SMOS Level 2 surface soil moisture (SM) retrieval product. The assimilation system uses a spatially distributed ensemble Kalman filter (EnKF) with seasonally varying climatological bias mitigation for Tb assimilation, whereas a time-invariant cumulative density function matching is used for SM retrieval assimilation. All assimilation experiments improve the soil moisture estimates compared to model-only simulations in terms of unbiased root-mean-square differences and anomaly correlations during the period from 1 July 2010 to 1 May 2015 and for 187 sites across the US. Especially in areas where the satellite data are most sensitive to surface soil moisture, large skill improvements (e.g., an increase in the anomaly correlation by 0.1) are found in the surface soil moisture. The domain-average surface and root-zone skill metrics are similar among the various assimilation experiments, but large differences in skill are found locally. The observation-minus-forecast residuals and analysis increments reveal large differences in how the observations add value in the Tb and SM retrieval assimilation systems. The distinct patterns of these diagnostics in the two systems reflect observation and model errors patterns that are not well captured in the assigned EnKF error parameters. Consequently, a localized optimization of the EnKF error parameters is needed to further improve Tb or SM retrieval

  13. Assimilation of SMOS Brightness Temperatures or Soil Moisture Retrievals into a Land Surface Model

    NASA Technical Reports Server (NTRS)

    De Lannoy, Gabrielle J. M.; Reichle, Rolf H.

    2016-01-01

    Three different data products from the Soil Moisture Ocean Salinity (SMOS) mission are assimilated separately into the Goddard Earth Observing System Model, version 5 (GEOS-5) to improve estimates of surface and root-zone soil moisture. The first product consists of multi-angle, dual-polarization brightness temperature (Tb) observations at the bottom of the atmosphere extracted from Level 1 data. The second product is a derived SMOS Tb product that mimics the data at a 40 degree incidence angle from the Soil Moisture Active Passive (SMAP) mission. The third product is the operational SMOS Level 2 surface soil moisture (SM) retrieval product. The assimilation system uses a spatially distributed ensemble Kalman filter (EnKF) with seasonally varying climatological bias mitigation for Tb assimilation, whereas a time-invariant cumulative density function matching is used for SM retrieval assimilation. All assimilation experiments improve the soil moisture estimates compared to model-only simulations in terms of unbiased root-mean-square differences and anomaly correlations during the period from 1 July 2010 to 1 May 2015 and for 187 sites across the US. Especially in areas where the satellite data are most sensitive to surface soil moisture, large skill improvements (e.g., an increase in the anomaly correlation by 0.1) are found in the surface soil moisture. The domain-average surface and root-zone skill metrics are similar among the various assimilation experiments, but large differences in skill are found locally. The observation-minus-forecast residuals and analysis increments reveal large differences in how the observations add value in the Tb and SM retrieval assimilation systems. The distinct patterns of these diagnostics in the two systems reflect observation and model errors patterns that are not well captured in the assigned EnKF error parameters. Consequently, a localized optimization of the EnKF error parameters is needed to further improve Tb or SM retrieval

  14. A soil diffusion-reaction model for surface COS flux: COSSM v1

    NASA Astrophysics Data System (ADS)

    Sun, W.; Maseyk, K.; Lett, C.; Seibt, U.

    2015-07-01

    Soil exchange of carbonyl sulfide (COS) is the second largest COS flux in terrestrial ecosystems. A novel application of COS is the separation of gross primary productivity (GPP) from concomitant respiration. This method requires that soil COS exchange is relatively small and can be well quantified. Existing models for soil COS flux have incorporated empirical temperature and moisture functions derived from laboratory experiments, but not explicitly resolved diffusion in the soil column. We developed a 1-D diffusion-reaction model for soil COS exchange that accounts for COS uptake and production, relates source-sink terms to environmental variables, and has an option to enable surface litter layers. We evaluated the model with field data from a wheat field (Southern Great Plains (SGP), OK, USA) and an oak woodland (Stunt Ranch Reserve, CA, USA). The model was able to reproduce all observed features of soil COS exchange such as diurnal variations and sink-source transitions. We found that soil COS uptake is strongly diffusion controlled, and limited by low COS concentrations in the soil if there is COS uptake in the litter layer. The model provides novel insights into the balance between soil COS uptake and production: a higher COS production capacity was required despite lower COS emissions during the growing season compared to the post-senescence period at SGP, and unchanged COS uptake capacity despite the dominant role of COS emissions after senescence. Once there is a database of soil COS parameters for key biomes, we expect the model will also be useful to simulate soil COS exchange at regional to global scales.

  15. A soil diffusion-reaction model for surface COS flux: COSSM v1

    NASA Astrophysics Data System (ADS)

    Sun, W.; Maseyk, K.; Lett, C.; Seibt, U.

    2015-10-01

    Soil exchange of carbonyl sulfide (COS) is the second largest COS flux in terrestrial ecosystems. A novel application of COS is the separation of gross primary productivity (GPP) from concomitant respiration. This method requires that soil COS exchange is relatively small and can be well quantified. Existing models for soil COS flux have incorporated empirical temperature and moisture functions derived from laboratory experiments but not explicitly resolved diffusion in the soil column. We developed a mechanistic diffusion-reaction model for soil COS exchange that accounts for COS uptake and production, relates source-sink terms to environmental variables, and has an option to enable surface litter layers. We evaluated the model with field data from a wheat field (Southern Great Plains (SGP), OK, USA) and an oak woodland (Stunt Ranch Reserve, CA, USA). The model was able to reproduce all observed features of soil COS exchange such as diurnal variations and sink-source transitions. We found that soil COS uptake is strongly diffusion controlled and limited by low COS concentrations in the soil if there is COS uptake in the litter layer. The model provides novel insights into the balance between soil COS uptake and production: a higher COS production capacity was required despite lower COS emissions during the growing season compared to the post-senescence period at SGP, and unchanged COS uptake capacity despite the dominant role of COS emissions after senescence. Once there is a database of soil COS parameters for key biomes, we expect the model will also be useful to simulate soil COS exchange at regional to global scales.

  16. Influences of pH, Temperature, and Moisture on Gaseous Tritium Uptake in Surface Soils

    PubMed Central

    Fallon, Robert D.

    1982-01-01

    In South Carolina surface soils, the uptake of gaseous tritium (T2, HT, or both) showed a broad optimal temperature response from about 20 to 50°C, with the highest rates at 35 to 45°C. The optimal pH was in the range of 4 to 7. Uptake rates declined at the wet and dry extremes in soil moisture content. Inhibition seen upon the addition of hydrogen or carbon monoxide to the soil atmosphere suggested that hydrogenase may be responsible for T2-HT uptake in soil. During the period of most rapid recovery in a 36-day incubation of reinoculated, sterilized soil, T2-HT uptake rates doubled every 2 to 4 days. Thus, T2-HT uptake appears to be biologically mediated. Soil uptake of T2-HT was not severely limited by pH, temperature, or moisture in the soils tested. Thus, rapid exchange of gaseous tritium into soil water must be expected and accounted for in modeling the isotope distributions around nuclear facilities. PMID:16346053

  17. Simple surface foam application enhances bioremediation of oil-contaminated soil in cold conditions.

    PubMed

    Jeong, Seung-Woo; Jeong, Jongshin; Kim, Jaisoo

    2015-04-09

    Landfarming of oil-contaminated soil is ineffective at low temperatures, because the number and activity of micro-organisms declines. This study presents a simple and versatile technique for bioremediation of diesel-contaminated soil, which involves spraying foam on the soil surface without additional works such as tilling, or supply of water and air. Surfactant foam containing psychrophilic oil-degrading microbes and nutrients was sprayed twice daily over diesel-contaminated soil at 6 °C. Removal efficiencies in total petroleum hydrocarbon (TPH) at 30 days were 46.3% for landfarming and 73.7% for foam-spraying. The first-order kinetic biodegradation rates for landfarming and foam-spraying were calculated as 0.019 d(-1) and 0.044 d(-1), respectively. Foam acted as an insulating medium, keeping the soil 2 °C warmer than ambient air. Sprayed foam was slowly converted to aqueous solution within 10-12h and infiltrated the soil, providing microbes, nutrients, water, and air for bioaugmentation. Furthermore, surfactant present in the aqueous solution accelerated the dissolution of oil from the soil, resulting in readily biodegradable aqueous form. Significant reductions in hydrocarbon concentration were simultaneously observed in both semi-volatile and non-volatile fractions. As the initial soil TPH concentration increased, the TPH removal rate of the foam-spraying method also increased. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Relationships between groundwater, surface water, and soil salinity in Polder 32, Southwest Bangladesh

    NASA Astrophysics Data System (ADS)

    Fry, D. C.; Ayers, J. C.

    2014-12-01

    In the coastal areas of Southwest Bangladesh polders are surrounded by tidal channels filled with brackish water. In the wet season, farmers create openings in the embankments to irrigate rice paddies. In the dry season, farmers do the same to create saline shrimp ponds. Residents on Polder 32, located within the Ganges-Brahmaputra-Meghna delta system, practice these seasonal farming techniques. Soils in the area are entisols, being sediment recently deposited, and contain mostly silt-sized particles. Brackish water in brine shrimp ponds may deposit salt in the soil, causing soil salinization. However, saline connate groundwater could also be contributing to soil salinization. Groundwater, surface water (fresh water pond, rice paddy and tidal channel water) and soil samples have been analyzed via inductively coupled plasma optical emission spectroscopy, inductively coupled plasma mass spectroscopy and ion chromatography in an attempt to correlate salinity measurements with each other in order to determine major sources of soil salinity. Multiple parameters, including distances of samples from tidal channels, inland streams, shrimp ponds and tube wells were measured to see if spatial correlations exist. Similarly, values from wet and dry seasons were compared to quantify temporal variations. Salt content in many soil samples were found to be high enough to significantly decrease rice yields. Continued soil salinization can decrease these yields even more, leading to farmers not producing enough food to sustain their families.

  19. Source apportionment and health risk assessment of trace metals in surface soils of Beijing metropolitan, China.

    PubMed

    Chen, Haiyang; Teng, Yanguo; Lu, Sijin; Wang, Yeyao; Wu, Jin; Wang, Jinsheng

    2016-02-01

    Understanding the exposure risks of trace metals in contamination soils and apportioning their sources are the basic preconditions for soil pollution prevention and control. In this study, a detailed investigation was conducted to assess the health risks of trace metals in surface soils of Beijing which is one of the most populated cities in the world and to apportion their potential sources. The data set of metals for 12 elements in 240 soil samples was collected. Pollution index and enrichment factor were used to identify the general contamination characteristic of soil metals. The probabilistic risk model was employed for health risk assessment, and a chemometrics technique, multivariate curve resolution-weighted alternating least squares (MCR-WALS), was applied to apportion sources. Results suggested that the soils in Beijing metropolitan region were contaminated by Hg, Cd, Cu, As, and Pb in varying degree, lying in the moderate pollution level. As a whole, the health risks posed by soil metals were acceptable or close to tolerable. Comparatively speaking, children and adult females were the relatively vulnerable populations for the non-carcinogenic and carcinogenic risks, respectively. Atmospheric deposition, fertilizers and agrochemicals, and natural source were apportioned as the potential sources determining the contents of trace metals in soils of Beijing area with contributions of 15.5%-16.4%, 5.9%-7.7% and 76.0%-78.6%, respectively.

  20. Estimation of Bare Surface Soil Moisture and Surface Roughness Parameter Using L-Band SAR Image Data

    NASA Technical Reports Server (NTRS)

    Shi, Jian-Cheng; Wang, James; Hsu, Ann; ONeill, Peggy; Engman, Edwin T.

    1997-01-01

    An algorithm based on a fit of the single-scattering Integral Equation Method (IEM) was developed to provide estimation of soil moisture and surface roughness parameter (a combination of rms roughness height and surface power spectrum) from quasi-polarized synthetic aperture radar (SAR) measurements. This algorithm was applied to a series of measurements acquired at L-band (1.25 GHz) from both AIRSAR (Airborne Synthetic Aperture Radar operated by Jet Propulsion Laboratory) and SIR-C (Spaceborne Imaging Radar-C) over a well-managed watershed in southwest Oklahoma. It was found that the two co-polarized backscattering coefficients and their combinations would provide the best input to the algorithm for estimation of soil moisture and roughness parameter. Application of the inversion algorithm to the co-polarized measurements of both AIRSAR and SIR-C resulted in estimated values of soil moisture and roughness parameter for bare and short-vegetated fields that compared favorably with those sampled on the ground. The root-mean-square (rms) errors of the comparison were found to be 3.4% and 1.9 dB for soil moisture and surface roughness parameter, respectively.

  1. Effect of Space Radiation Processing on Lunar Soil Surface Chemistry: X-Ray Photoelectron Spectroscopy Studies

    NASA Technical Reports Server (NTRS)

    Dukes, C.; Loeffler, M.J.; Baragiola, R.; Christoffersen, R.; Keller, J.

    2009-01-01

    Current understanding of the chemistry and microstructure of the surfaces of lunar soil grains is dominated by a reference frame derived mainly from electron microscopy observations [e.g. 1,2]. These studies have shown that the outermost 10-100 nm of grain surfaces in mature lunar soil finest fractions have been modified by the combined effects of solar wind exposure, surface deposition of vapors and accretion of impact melt products [1,2]. These processes produce surface-correlated nanophase Feo, host grain amorphization, formation of surface patinas and other complex changes [1,2]. What is less well understood is how these changes are reflected directly at the surface, defined as the outermost 1-5 atomic monolayers, a region not easily chemically characterized by TEM. We are currently employing X-ray Photoelectron Spectroscopy (XPS) to study the surface chemistry of lunar soil samples that have been previously studied by TEM. This work includes modification of the grain surfaces by in situ irradiation with ions at solar wind energies to better understand how irradiated surfaces in lunar grains change their chemistry once exposed to ambient conditions on earth.

  2. The Influence of Rotation, Tillage and Row Spacing on Near-Surface Soil Temperature for Winter Wheat in Southern Alberta

    SciTech Connect

    Larney, F. J.; Ren, Tennis L.; McGinn, Sean M.; Lindwall, C W.; Izaurralde, R Cesar C.

    2003-02-01

    The influence of rotation, tillage and row spacing on near-surface soil temperature for winter wheat in southern Alberta. Rotation, tillage and row spacing and their effects on surface residue levels can modify soil temperature. Our study investigated the effect of rotation, tillage and row spacing on near-surface (0.025 m) soil temperature under winter wheat (Triticum aestivum L.) in 1993-94 and 1994-95.

  3. Global observation-based diagnosis of soil moisture control on land surface flux partition

    NASA Astrophysics Data System (ADS)

    Gallego-Elvira, Belen; Taylor, Christopher M.; Harris, Phil P.; Ghent, Darren; Veal, Karen L.; Folwell, Sonja S.

    2016-04-01

    Soil moisture plays a central role in the partition of available energy at the land surface between sensible and latent heat flux to the atmosphere. As soils dry out, evapotranspiration becomes water-limited ("stressed"), and both land surface temperature (LST) and sensible heat flux rise as a result. This change in surface behaviour during dry spells directly affects critical processes in both the land and the atmosphere. Soil water deficits are often a precursor in heat waves, and they control where feedbacks on precipitation become significant. State-of-the-art global climate model (GCM) simulations for the Coupled Model Intercomparison Project Phase 5 (CMIP5) disagree on where and how strongly the surface energy budget is limited by soil moisture. Evaluation of GCM simulations at global scale is still a major challenge owing to the scarcity and uncertainty of observational datasets of land surface fluxes and soil moisture at the appropriate scale. Earth observation offers the potential to test how well GCM land schemes simulate hydrological controls on surface fluxes. In particular, satellite observations of LST provide indirect information about the surface energy partition at 1km resolution globally. Here, we present a potentially powerful methodology to evaluate soil moisture stress on surface fluxes within GCMs. Our diagnostic, Relative Warming Rate (RWR), is a measure of how rapidly the land warms relative to the overlying atmosphere during dry spells lasting at least 10 days. Under clear skies, this is a proxy for the change in sensible heat flux as soil dries out. We derived RWR from MODIS Terra and Aqua LST observations, meteorological re-analyses and satellite rainfall datasets. Globally we found that on average, the land warmed up during dry spells for 97% of the observed surface between 60S and 60N. For 73% of the area, the land warmed faster than the atmosphere (positive RWR), indicating water stressed conditions and increases in sensible heat flux

  4. A comparison of six methods for measuring soil-surface carbon dioxide fluxes

    USGS Publications Warehouse

    Norman, J.M.; Kucharik, C.J.; Gower, S.T.; Baldocchi, D.D.; Crill, P.M.; Rayment, M.; Savage, K.; Striegl, R.G.

    1997-01-01

    Measurements of soil-surface CO2 fluxes are important for characterizing the carbon budget of boreal forests because these fluxes can be the second largest component of the budget. Several methods for measuring soil-surface CO2 fluxes are available: (1) closed-dynamic-chamber systems, (2) closed-static-chamber systems, (3) open-chamber systems, and (4) eddy covariance systems. This paper presents a field comparison of six individual systems for measuring soil-surface CO2 fluxes with each of the four basic system types represented. A single system is used as a reference and compared to each of the other systems individually in black spruce (Picea mariana), jack pine (Pinus banksiana), or aspen (Populus tremuloides) forests. Fluxes vary from 1 to 10 ??mol CO2 m-2 s-1. Adjustment factors to bring all of the systems into agreement vary from 0.93 to 1.45 with an uncertainty of about 10-15%.

  5. Soil Moisture Active Passive (SMAP) Mission Level 4 Surface and Root Zone Soil Moisture (L4_SM) Product Specification Document

    NASA Technical Reports Server (NTRS)

    Reichle, Rolf H.; Ardizzone, Joseph V.; Kim, Gi-Kong; Lucchesi, Robert A.; Smith, Edmond B.; Weiss, Barry H.

    2015-01-01

    This is the Product Specification Document (PSD) for Level 4 Surface and Root Zone Soil Moisture (L4_SM) data for the Science Data System (SDS) of the Soil Moisture Active Passive (SMAP) project. The L4_SM data product provides estimates of land surface conditions based on the assimilation of SMAP observations into a customized version of the NASA Goddard Earth Observing System, Version 5 (GEOS-5) land data assimilation system (LDAS). This document applies to any standard L4_SM data product generated by the SMAP Project. The Soil Moisture Active Passive (SMAP) mission will enhance the accuracy and the resolution of space-based measurements of terrestrial soil moisture and freeze-thaw state. SMAP data products will have a noteworthy impact on multiple relevant and current Earth Science endeavors. These include: Understanding of the processes that link the terrestrial water, the energy and the carbon cycles, Estimations of global water and energy fluxes over the land surfaces, Quantification of the net carbon flux in boreal landscapes Forecast skill of both weather and climate, Predictions and monitoring of natural disasters including floods, landslides and droughts, and Predictions of agricultural productivity. To provide these data, the SMAP mission will deploy a satellite observatory in a near polar, sun synchronous orbit. The observatory will house an L-band radiometer that operates at 1.40 GHz and an L-band radar that operates at 1.26 GHz. The instruments will share a rotating reflector antenna with a 6 meter aperture that scans over a 1000 km swath.

  6. Monitoring Land Surface Soil Moisture from Space with in-Situ Sensors Validation: The Huntsville Example

    NASA Technical Reports Server (NTRS)

    Wu, Steve Shih-Tseng

    1997-01-01

    Based on recent advances in microwave remote sensing of soil moisture and in pursuit of research interests in areas of hydrology, soil climatology, and remote sensing, the Center for Hydrology, Soil Climatology, and Remote Sensing (HSCARS) conducted the Huntsville '96 field experiment in Huntsville, Alabama from July 1-14, 1996. We, researchers at the Global Hydrology and Climate Center's MSFC/ES41, are interested in using ground-based microwave sensors, to simulate land surface brightness signatures of those spaceborne sensors that were in operation or to be launched in the near future. The analyses of data collected by the Advanced Microwave Precipitation Radiometer (AMPR) and the C-band radiometer, which together contained five frequencies (6.925,10.7,19.35, 37.1, and 85.5 GHz), and with concurrent in-situ collection of surface cover conditions (surface temperature, surface roughness, vegetation, and surface topology) and soil moisture content, would result in a better understanding of the data acquired over land surfaces by the Special Sensor Microwave Imager (SSM/I), the Tropical Rainfall Measuring Mission Microwave Imager (TMI), and the Advanced Microwave Scanning Radiometer (AMSR), because these spaceborne sensors contained these five frequencies. This paper described the approach taken and the specific objective to be accomplished in the Huntsville '97 field experiment.

  7. Overstory removal and residue treatments affect soil surface, air, and soil temperature: implications for seedling survival

    Treesearch

    Roger D. Hungerford; Ronald E. Babbitt

    1987-01-01

    Potentially lethal ground surface temperatures were measured at three locations in the Northern Rocky Mountains but occurred more frequently under treatments with greater overstory removal. Observed maximum and minimum temperatures of exposed surfaces are directly related to the thermal properties of the surface materials. Survival of planted seedlings was consistent...

  8. Mapping surface soil moisture using an aircraft-based passive microwave instrument: algorithm and example

    NASA Astrophysics Data System (ADS)

    Jackson, T. J.; Le Vine, David E.

    1996-10-01

    Microwave remote sensing at L-band (21 cm wavelength) can provide a direct measurement of the surface soil moisture for a range of cover conditions and within reasonable error bounds. Surface soil moisture observations are rare and, therefore, the use of these data in hydrology and other disciplines has not been fully explored or developed. Without satellite-based observing systems, the only way to collect these data in large-scale studies is with an aircraft platform. Recently, aircraft systems such as the push broom microwave radiometer (PBMR) and the electronically scanned thinned array radiometer (ESTAR) have been developed to facilitate such investigations. In addition, field experiments have attempted to collect the passive microwave data as part of an integrated set of hydrologic data. One of the most ambitious of these investigations was the Washita'92 experiment. Preliminary analysis of these data has shown that the microwave observations are indicative of deterministic spatial and temporal variations in the surface soil moisture. Users of these data should be aware of a number of issues related to using aircraft-based systems and practical approaches to applying soil moisture estimation algorithms to large data sets. This paper outlines the process of mapping surface soil moisture from an aircraft-based passive microwave radiometer system for the Washita'92 experiment.

  9. Assimilation of ASCAT near-surface soil moisture into the SIM hydrological model over France

    NASA Astrophysics Data System (ADS)

    Draper, C.; Mahfouf, J.-F.; Calvet, J.-C.; Martin, E.; Wagner, W.

    2011-12-01

    This study examines whether the assimilation of remotely sensed near-surface soil moisture observations might benefit an operational hydrological model, specifically Météo-France's SAFRAN-ISBA-MODCOU (SIM) model. Soil moisture data derived from ASCAT backscatter observations are assimilated into SIM using a Simplified Extended Kalman Filter (SEKF) over 3.5 years. The benefit of the assimilation is tested by comparison to a delayed cut-off version of SIM, in which the land surface is forced with more accurate atmospheric analyses, due to the availability of additional atmospheric observations after the near-real time data cut-off. However, comparing the near-real time and delayed cut-off SIM models revealed that the main difference between them is a dry bias in the near-real time precipitation forcing, which resulted in a dry bias in the root-zone soil moisture and associated surface moisture flux forecasts. While assimilating the ASCAT data did reduce the root-zone soil moisture dry bias (by nearly 50%), this was more likely due to a bias within the SEKF, than due to the assimilation having accurately responded to the precipitation errors. Several improvements to the assimilation are identified to address this, and a bias-aware strategy is suggested for explicitly correcting the model bias. However, in this experiment the moisture added by the SEKF was quickly lost from the model surface due to the enhanced surface fluxes (particularly drainage) induced by the wetter soil moisture states. Consequently, by the end of each winter, during which frozen conditions prevent the ASCAT data from being assimilated, the model land surface had returned to its original (dry-biased) climate. This highlights that it would be more effective to address the precipitation bias directly, than to correct it by constraining the model soil moisture through data assimilation.

  10. Massively Parallel Computation of Soil Surface Roughness Parameters on A Fermi GPU

    NASA Astrophysics Data System (ADS)

    Li, Xiaojie; Song, Changhe

    2016-06-01

    Surface roughness is description of the surface micro topography of randomness or irregular. The standard deviation of surface height and the surface correlation length describe the statistical variation for the random component of a surface height relative to a reference surface. When the number of data points is large, calculation of surface roughness parameters is time-consuming. With the advent of Graphics Processing Unit (GPU) architectures, inherently parallel problem can be effectively solved using GPUs. In this paper we propose a GPU-based massively parallel computing method for 2D bare soil surface roughness estimation. This method was applied to the data collected by the surface roughness tester based on the laser triangulation principle during the field experiment in April 2012. The total number of data points was 52,040. It took 47 seconds on a Fermi GTX 590 GPU whereas its serial CPU version took 5422 seconds, leading to a significant 115x speedup.

  11. SIR-C Measurements of Soil Moisture, Vegetation and Surface Roughness and their Hydrological Application

    NASA Technical Reports Server (NTRS)

    Wang, James R.

    1996-01-01

    The objectives of the study are: (1) Analysis of SIR-C/X-SAR response to soil moisture, vegetation and surface roughness and development of an algorithm to retrieve these parameters; (2) Combination of the visible and near-infrared data and the SIR-C/X-SAR data to improve the range and accuracy of vegetation classification; (3) Testing of theoretical models for microwave propagation with SIR-C/X-SAR and microwave radiometric measurements over rough surfaces; and (4) Evaluation of a water balance model using SIR-C/X-SAR derived soil moisture values and other ancillary data. Progress, significant results and future plans are presented.

  12. SIR-C Measurements of Soil Moisture, Vegetation and Surface Roughness and their Hydrological Application

    NASA Technical Reports Server (NTRS)

    Wang, James R.

    1996-01-01

    The objectives of the study are: (1) Analysis of SIR-C/X-SAR response to soil moisture, vegetation and surface roughness and development of an algorithm to retrieve these parameters; (2) Combination of the visible and near-infrared data and the SIR-C/X-SAR data to improve the range and accuracy of vegetation classification; (3) Testing of theoretical models for microwave propagation with SIR-C/X-SAR and microwave radiometric measurements over rough surfaces; and (4) Evaluation of a water balance model using SIR-C/X-SAR derived soil moisture values and other ancillary data. Progress, significant results and future plans are presented.

  13. Soil and glass surface photodegradation of etofenprox under simulated california rice growing conditions.

    PubMed

    Vasquez, Martice; Cahill, Thomas; Tjeerdema, Ronald

    2011-07-27

    Photolysis is an important degradation process to consider when evaluating a pesticide's persistence in a rice field environment. To simulate both nonflooded and flooded California rice field conditions, the photolytic degradation of etofenprox, an ether pyrethroid, was characterized on an air-dried rice soil and a flooded rice soil surface by determination of its half-life (t(1/2)), dissipation rate constant (k) and identification and quantitation of degradation products using LC/MS/MS. Photodegradation was also characterized on a glass surface alone to rule out confounding soil factors. Measured photolytic dissipation rates were used as input parameters into a multimedia environmental fate model to predict etofenprox persistence in a rice field environment. Photolytic degradation proceeded at a faster rate (0.23/day, t(1/2) = 3.0 days) on the flooded soil surface compared to the air-dried surface (0.039/day, t(1/2) = 18 days). Etofenprox degradation occurred relatively quickly on the glass surface (3.1/day, t(1/2) = 0.23 days or 5.5 h) compared to both flooded and air-dried soil layers. Oxidation of the ether moiety to the ester was the major product on all surfaces (max % yield range = 0.2 ± 0.1% to 9.3 ± 2.3%). The hydroxylation product at the 4' position of the phenoxy phenyl ring was detected on all surfaces (max % yield range = 0.2 ± 0.1% to 4.1 ± 1.0%). The air-dried soil surface did not contain detectable residues of the ester cleavage product, whereas it was quantitated on the flooded soil (max % yield = 0.6 ± 0.3%) and glass surface (max % yield = 3.6 ± 0.6%). Dissipation of the insecticide in dark controls was significantly different (p < 0.05) compared to the light-exposed surfaces indicating that degradation was by photolysis. Laboratory studies and fate model predictions suggest photolysis will be an important process in the overall degradation of etofenprox in a rice field environment.

  14. Calculations of microwave brightness temperature of rough soil surfaces: Bare field

    NASA Technical Reports Server (NTRS)

    Mo, T.; Schmugge, T. J.; Wang, J. R.

    1985-01-01

    A model for simulating the brightness temperatures of soils with rough surfaces is developed. The surface emissivity of the soil media is obtained by the integration of the bistatic scattering coefficients for rough surfaces. The roughness of a soil surface is characterized by two parameters, the surface height standard deviation sigma and its horizontal correlation length l. The model calculations are compared to the measured angular variations of the polarized brightness temperatures at both 1.4 GHz and 5 GHz frequences. A nonlinear least-squares fitting method is used to obtain the values of delta and l that best characterize the surface roughness. The effect of shadowing is incorporated by introducing a function S(theta), which represents the probability that a point on a rough surface is not shadowed by other parts of the surface. The model results for the horizontal polarization are in excellent agreement with the data. However, for the vertical polarization, some discrepancies exist between the calculations and data, particularly at the 1.4 GHz frequency. Possible causes of the discrepancy are discussed.

  15. Influence of vegetation, soil and antecedent soil moisture on the variability of surface runoff coefficients at the plot scale in the eastern alps

    NASA Astrophysics Data System (ADS)

    Chifflard, P.; Kohl, B.; Markart, G.; Kirnbauer, R.

    2009-04-01

    Modelling the runoff of a catchment in a high spatial resolution, you need to know the potential of a single plot to generate surface runoff. The portion of surface runoff is highly significant for storm runoff events, accordingly, it mainly forms the hydrograph. In this study, the influence of vegetation, soil features and antecedent soil moisture on generating surface runoff at the plot scale have been analysed. To achieve an appropriate fit of the plots, a plot sizes between 50 and 400 m² were chosen. The rainfall intensities ranged between 10 mm/h and 100 mm/h. Based on 260 rain simulations with a transportable sprinkling instrumentation on representative plots in the eastern Alps (Austria, Italy, Germany), including investigations on land-use, vegetation cover and soil physical characteristics, various soil-vegetation complexes and their surface runoff processes have been be analysed. Additionally, we investigated flow paths, travel distance, infiltration hindrance, flow resistance and overland flow velocity. The soil water status was monitored by using TDR-probes, which had been installed in two profiles within the plot in different depths ranging from 5 cm to 40 cm. For every sprinkling experiment, a surface runoff coefficient was calculated as the ratio between total rainfall amount and surface runoff. With this substantial dataset, the regression analysis was used to examine the influence of the hydrological key factors as soil, vegetation and initial soil moisture condition on the distribution functions of the surface runoff coefficient. The first results show that the vegetation cover is very important for the surface runoff. If initial soils are covered by alpine or sub-alpine pioneering vegetation surface runoff can be found very scarce. If these initial soils are covered i.e. by subalpine nardus grasslands the surface runoff coefficients range from 0.1 up to 0.8. On the other hand it can be shown that soils with a high bulk density mainly generate

  16. Age and activation of microbial communities in soils under burial mounds and in recent surface soils of steppe zone

    NASA Astrophysics Data System (ADS)

    Demkina, T. S.; Khomutova, T. E.; Kashirskaya, N. N.; Demkina, E. V.; Stretovich, I. V.; El-Registan, G. I.; Demkin, V. A.

    2008-12-01

    Chestnut paleosols buried under steppe kurgans about 4800, 4000, and 2000 years ago and their background analogues were studied in the dry steppe zone on the Volga-Don interfluve. Morphological, chemical, microbiological, biochemical, and radiocarbon studies were performed. Paleoclimatic conditions in the region were reconstructed on the basis of paleosol data. The ages of microbial fractions isolated from the buried and surface soils were determined using the method of 14C atomic mass-spectrometry. It reached 2100 years in the A1 horizon of the buried paleosol, which corresponded to the archaeological age of the kurgan (1st century AD). The ages of microbial biomass isolated from the B2 horizons of the buried paleosol and the background surface soil comprised 3680 ± 35 and 3300 ± 30 years, respectively. The obtained data confirmed our assumption about preservation of microorganisms of the past epochs in the paleosols buried under archaeological monuments. It is ensured by various mechanisms of adaptation of soil microbial communities to unfavorable environmental conditions (anabiosis, transformation of bacteria into nanoforms, etc.). The possibility to stimulate germination of the ancient dormant microbial pool isolated from the buried paleosols by 2-3 orders of magnitude with the use of β-indolyl-3-acetic acid as a signal substance was demonstrated.

  17. Modelling and interpreting biologically crusted dryland soil sub-surface structure using automated micropenetrometry

    NASA Astrophysics Data System (ADS)

    Hoon, Stephen R.; Felde, Vincent J. M. N. L.; Drahorad, Sylvie L.; Felix-Henningsen, Peter

    2015-04-01

    Soil penetrometers are used routinely to determine the shear strength of soils and deformable sediments both at the surface and throughout a depth profile in disciplines as diverse as soil science, agriculture, geoengineering and alpine avalanche-safety (e.g. Grunwald et al. 2001, Van Herwijnen et al. 2009). Generically, penetrometers comprise two principal components: An advancing probe, and a transducer; the latter to measure the pressure or force required to cause the probe to penetrate or advance through the soil or sediment. The force transducer employed to determine the pressure can range, for example, from a simple mechanical spring gauge to an automatically data-logged electronic transducer. Automated computer control of the penetrometer step size and probe advance rate enables precise measurements to be made down to a resolution of 10's of microns, (e.g. the automated electronic micropenetrometer (EMP) described by Drahorad 2012). Here we discuss the determination, modelling and interpretation of biologically crusted dryland soil sub-surface structures using automated micropenetrometry. We outline a model enabling the interpretation of depth dependent penetration resistance (PR) profiles and their spatial differentials using the model equations, σ {}(z) ={}σ c0{}+Σ 1n[σ n{}(z){}+anz + bnz2] and dσ /dz = Σ 1n[dσ n(z) /dz{} {}+{}Frn(z)] where σ c0 and σ n are the plastic deformation stresses for the surface and nth soil structure (e.g. soil crust, layer, horizon or void) respectively, and Frn(z)dz is the frictional work done per unit volume by sliding the penetrometer rod an incremental distance, dz, through the nth layer. Both σ n(z) and Frn(z) are related to soil structure. They determine the form of σ {}(z){} measured by the EMP transducer. The model enables pores (regions of zero deformation stress) to be distinguished from changes in layer structure or probe friction. We have applied this method to both artificial calibration soils in the

  18. High diversity of bacterial mercuric reductase genes from surface and sub-surface floodplain soil (Oak Ridge, USA).

    PubMed

    Oregaard, Gunnar; Sørensen, Søren J

    2007-09-01

    DNA was extracted from different depth soils (0-5, 45-55 and 90-100 cm below surface) sampled at Lower East Fork Poplar Creek floodplain (LEFPCF), Oak Ridge (TN, USA). The presence of merA genes, encoding the mercuric reductase, the key enzyme in detoxification of mercury in bacteria, was examined by PCR targeting Actinobacteria, Firmicutes or beta/gamma-Proteobacteria. beta/gamma-Proteobacteria merA genes were successfully amplified from all soils, whereas Actinobacteria were amplified only from surface soil. merA clone libraries were constructed and sequenced. beta/gamma-Proteobacteria sequences revealed high diversity in all soils, but limited vertical similarity. Less than 20% of the operational taxonomic units (OTU) (DNA sequences > or = 95% identical) were shared between the different soils. Only one of the 62 OTU was > or = 95% identical to a GenBank sequence, highlighting that cultivated bacteria are not representative of what is found in nature. Fewer merA sequences were obtained from the Actinobacteria, but these were also diverse, and all were different from GenBank sequences. A single clone was most closely related to merA of alpha-Proteobacteria. An alignment of putative merA genes of genome sequenced mainly marine alpha-Proteobacteria was used for design of merA primers. PCR amplification of soil alpha-Proteobacteria isolates and sequencing revealed that they were very different from the genome-sequenced bacteria (only 62%-66% identical at the amino-acid level), although internally similar. In light of the high functional diversity of mercury resistance genes and the limited vertical distribution of shared OTU, we discuss the role of horizontal gene transfer as a mechanism of bacterial adaptation to mercury.

  19. Dew-worms in white nights: High latitude light constrains earthworm (Lumbricus terrestris) behaviour at the soil surface

    USDA-ARS?s Scientific Manuscript database

    Soil is an effective barrier to light penetration that limits the direct influence of light on belowground organisms. Variation in aboveground light conditions, however, is important to soil-dwelling animals that are periodically active on the soil surface. A prime example is the earthworm Lumbricus...

  20. The effects of landscape cover on surface soils in a low density residential neighborhood in Baltimore, Maryland

    Treesearch

    Ian D. Yesilonis; Richard Pouyat; J. Russell-Anelli; E. Powell

    2015-01-01

    Previous studies at the scale of a city have shown that surface soil nutrients, pH, and soil organic matter (SOM) can vary by land cover, land use, and management. This study was conducted in Baltimore County, Maryland, to quantify the differences in characteristics of soil in a residential neighborhood and adjacent forest patch sampling at a fine scale. The first...

  1. Soil heat flux calculation for sunlit and shaded surfaces under row crops: 1 - Model Development and sensitivity analysis

    USDA-ARS?s Scientific Manuscript database

    Soil heat flux at the surface (G0) is strongly influenced by whether the soil is shaded or sunlit, and therefore can have large spatial variability for incomplete vegetation cover, such as across the interrows of row crops. Most practical soil-plant-atmosphere energy balance models calculate G0 as a...

  2. Transport of trace metals in runoff from soil and pond ash feedlot surfaces

    USGS Publications Warehouse

    Vogel, J.R.; Gilley, J.E.; Cottrell, G.L.; Woodbury, B.L.; Berry, E.D.; Eigenbert, R.A.

    2011-01-01

    The use of pond ash (fly ash that has been placed in evaporative ponds for storage and subsequently dewatered) for feedlot surfaces provides a drier environment for livestock and furnishes economic benefits. However, pond ash is known to have high concentrations of trace elements, and the runoff water-quality effects of feedlot surfaces amended with pond ash are not well defined. For this study, two experimental units (plots) were established in eight feedlot pens. Four of the pens contained unamended soil surfaces, and the remaining four pens had pond-ash amended surfaces. Before each test, unconsolidated surface material was removed from four of the plots for each of the amendment treatments, resulting in eight unamended plots and eight pond-ash amended plots. Concentrations for 23 trace elements were measured in cattle feedlot surface material and in the runoff water from three simulated rainfall events. Trace element concentrations in surface material and runoff did not differ between surface consolidation treatments. Amending the feedlot surface material with pond ash resulted in a significant increase in concentration for 14 of the 17 trace elements. Runoff concentrations for 21 trace elements were affected by pond-ash amendment. Sixteen of 21 trace element concentrations that differed significantly were greater in runoff from unamended soil surfaces. Concentrations in runoff were significantly correlated with concentrations in feedlot surface material for boron, manganese, molybdenum, selenium, and uranium.

  3. Space Weathering Effects in Lunar Soils: The Roles of Surface Exposure Time and Bulk Chemical Composition

    NASA Technical Reports Server (NTRS)

    Zhang, Shouliang; Keller, Lindsay P.

    2011-01-01

    Space weathering effects on lunar soil grains result from both radiation-damaged and deposited layers on grain surfaces. Typically, solar wind irradiation forms an amorphous layer on regolith silicate grains, and induces the formation of surficial metallic Fe in Fe-bearing minerals [1,2]. Impacts into the lunar regolith generate high temperature melts and vapor. The vapor component is largely deposited on the surfaces of lunar soil grains [3] as is a fraction of the melt [4, this work]. Both the vapor-deposits and the deposited melt typically contain nanophase Fe metal particles (npFe0) as abundant inclusions. The development of these rims and the abundance of the npFe0 in lunar regolith, and thus the optical properties, vary with the soil mineralogy and the length of time the soil grains have been exposed to space weathering effects [5]. In this study, we used the density of solar flare particle tracks in soil grains to estimate exposure times for individual grains and then perform nanometer-scale characterization of the rims using transmission electron microscopy (TEM). The work involved study of lunar soil samples with different mineralogy (mare vs. highland) and different exposure times (mature vs. immature).

  4. Optimal averaging of soil moisture predictions from ensemble land surface model simulations

    NASA Astrophysics Data System (ADS)

    Crow, W. T.; Su, C.-H.; Ryu, D.; Yilmaz, M. T.

    2015-11-01

    The correct interpretation of ensemble information obtained from the parallel implementation of multiple land surface models (LSMs) requires information concerning the LSM ensemble's mutual error covariance. Here we propose a technique for obtaining such information using an instrumental variable (IV) regression approach and comparisons against a long-term surface soil moisture data set acquired from satellite remote sensing. Application of the approach to multimodel ensemble soil moisture output from Phase 2 of the North American Land Data Assimilation System (NLDAS-2) and European Space Agency (ESA) Soil Moisture (SM) Essential Climate Variable (ECV) data set allows for the calculation of optimal weighting coefficients for individual members of the NLDAS-2 LSM ensemble and a biased-minimized estimate of uncertainty in a deterministic soil moisture analysis derived via optimal averaging. As such, it provides key information required to accurately condition soil moisture expectations using information gleaned from a multimodel LSM ensemble. However, existing continuity and rescaling concerns surrounding the generation of long-term, satellite-based soil moisture products must likely be resolved before the proposed approach can be applied with full confidence.

  5. A Comparison of Land Surface Model Soil Hydraulic Properties Estimated by Inverse Modeling and Pedotransfer Functions

    NASA Technical Reports Server (NTRS)

    Gutmann, Ethan D.; Small, Eric E.

    2007-01-01

    Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.

  6. Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

    USGS Publications Warehouse

    Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

    2017-01-01

    Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

  7. A Comparison of Land Surface Model Soil Hydraulic Properties Estimated by Inverse Modeling and Pedotransfer Functions

    NASA Technical Reports Server (NTRS)

    Gutmann, Ethan D.; Small, Eric E.

    2007-01-01

    Soil hydraulic properties (SHPs) regulate the movement of water in the soil. This in turn plays an important role in the water and energy cycles at the land surface. At present, SHPS are commonly defined by a simple pedotransfer function from soil texture class, but SHPs vary more within a texture class than between classes. To examine the impact of using soil texture class to predict SHPS, we run the Noah land surface model for a wide variety of measured SHPs. We find that across a range of vegetation cover (5 - 80% cover) and climates (250 - 900 mm mean annual precipitation), soil texture class only explains 5% of the variance expected from the real distribution of SHPs. We then show that modifying SHPs can drastically improve model performance. We compare two methods of estimating SHPs: (1) inverse method, and (2) soil texture class. Compared to texture class, inverse modeling reduces errors between measured and modeled latent heat flux from 88 to 28 w/m(exp 2). Additionally we find that with increasing vegetation cover the importance of SHPs decreases and that the van Genuchten m parameter becomes less important, while the saturated conductivity becomes more important.

  8. Soil Surface Leak Detection From Carbon Storage Sites Using ∆(CO2:O2) Measurements

    NASA Astrophysics Data System (ADS)

    Alam, M. M.; Norman, A. L.; Layzell, D. B.

    2015-12-01

    The early detection and remediation of CO2 leaks from Carbon Capture and Storage (CCS) sites is essential for the safety and public support of the technology. A model that integrates gas diffusion, mass flow and biological processes in soils was developed and used to predict the ∆CO2 and ∆O2 concentration differential between the soil surface and the bulk atmosphere under a wide range of environmental conditions that include temperature, soil gas and water content, soil respiratory quotient and rate of O2 uptake, soil porosity and CO2 leakage rate. The results predicted that measurement of ∆(CO2:O2) measurements at the soil surface relative to air should be able to detect a CCS leak as low as 2 µmol/m2/sec. To test this hypothesis, a gas analysis system was designed and constructed. It should allow a series of experiments under controlled conditions to test all aspects of the model. It is hoped that the results from this work will ultimately lead to the development of a new instrument and protocol for the early detection of CO2 leaks from a geological storage sites.

  9. The role of fire on soil mounds and surface roughness in the Mojave Desert

    USGS Publications Warehouse

    Soulard, Christopher E.; Esque, Todd C.; Bedford, David R.; Bond, Sandra

    2013-01-01

    A fundamental question in arid land management centers on understanding the long-term effects of fire on desert ecosystems. To assess the effects of fire on surface topography, soil roughness, and vegetation, we used terrestrial (ground-based) LiDAR to quantify the differences between burned and unburned surfaces by creating a series of high-resolution vegetation structure and bare-earth surface models for six sample plots in the Grand Canyon-Parashant National Monument, Arizona. We find that 11 years following prescribed burns, mound volumes, plant heights, and soil-surface roughness were significantly lower on burned relative to unburned plots. Results also suggest a linkage between vegetation and soil mounds, either through accretion or erosion mechanisms such as wind and/or water erosion. The biogeomorphic implications of fire-induced changes are significant. Reduced plant cover and altered soil surfaces from fire likely influence seed residence times, inhibit seed germination and plant establishment, and affect other ecohydrological processes.

  10. Assimilation of ASCAT near-surface soil moisture into the French SIM hydrological model

    NASA Astrophysics Data System (ADS)

    Draper, C.; Mahfouf, J.-F.; Calvet, J.-C.; Martin, E.; Wagner, W.

    2011-06-01

    The impact of assimilating near-surface soil moisture into the SAFRAN-ISBA-MODCOU (SIM) hydrological model over France is examined. Specifically, the root-zone soil moisture in the ISBA land surface model is constrained over three and a half years, by assimilating the ASCAT-derived surface degree of saturation product, using a Simplified Extended Kalman Filter. In this experiment ISBA is forced with the near-real time SAFRAN analysis, which analyses the variables required to force ISBA from relevant observations available before the real time data cut-off. The assimilation results are tested against ISBA forecasts generated with a higher quality delayed cut-off SAFRAN analysis. Ideally, assimilating the ASCAT data will constrain the ISBA surface state to correct for errors in the near-real time SAFRAN forcing, the most significant of which was a substantial dry bias caused by a dry precipitation bias. The assimilation successfully reduced the mean root-zone soil moisture bias, relative to the delayed cut-off forecasts, by close to 50 % of the open-loop value. The improved soil moisture in the model then led to significant improvements in the forecast hydrological cycle, reducing the drainage, runoff, and evapotranspiration biases (by 17 %, 11 %, and 70 %, respectively). When coupled to the MODCOU hydrogeological model, the ASCAT assimilation also led to improved streamflow forecasts, increasing the mean discharge ratio, relative to the delayed cut off forecasts, from 0.68 to 0.76. These results demonstrate that assimilating near-surface soil moisture observations can effectively constrain the SIM model hydrology, while also confirming the accuracy of the ASCAT surface degree of saturation product. This latter point highlights how assimilation experiments can contribute towards the difficult issue of validating remotely sensed land surface observations over large spatial scales.

  11. Bacteria-mineral interactions in soil and their effect on particle surface properties

    NASA Astrophysics Data System (ADS)

    Miltner, Anja; Achtenhagen, Jan; Goebel, Marc-Oliver; Bachmann, Jörg; Kästner, Matthias

    2015-04-01

    Interactions between bacteria or their residues and mineral surfaces play an important role for soil processes and properties. It is well known that bacteria tend to grow attached to surfaces and that they get more hydrophobic when grown under stress conditions. In addition, bacterial and fungal biomass residues have recently been shown to contribute to soil organic matter formation. The attachment of bacteria or their residues to soil minerals can be expected to modify the surface properties of these particles, in particular the wettability. We hypothesize that the extent of the effect depends on the surface properties of the bacteria, which change depending on environmental conditions. As the wettability of soil particles is crucial for the distribution and the availability of water, we investigated the effect of both living cells and bacterial residues (cell envelope fragments and cytosol) on the wettability of model mineral particles in a simplified laboratory system. We grew Pseudomonas putida cells in mineral medium either without (unstressed) or with additional 1.5 M NaCl (osmotically stressed). After 2 h of incubation, the cells were disintegrated by ultrasonic treatment. Different amounts of either intact cells, cell envelope fragments or cytosol (each corresponding to 108, 109, or 1010 cells per gram of mineral) were mixed with quartz sand, quartz silt or kaolinite. The bacteria-mineral associations were air-dried for 2 hours and analyzed for their contact angle. We found that the surfaces of osmotically stressed cells were more hydrophobic than the surfaces of unstressed cells and that the bacteria-mineral associations had higher contact angles than the pure minerals. A rather low surface coverage (~10%) of the mineral surfaces by bacteria was sufficient to increase the contact angle significantly, and the different wettabilities of stressed and unstressed cells were reflected in the contact angles of the bacteria-mineral associations. The increases in

  12. Coupled simulation of surface runoff and soil water flow using multi-objective parameter estimation

    NASA Astrophysics Data System (ADS)

    Köhne, John Maximilian; Wöhling, Thomas; Pot, Valérie; Benoit, Pierre; Leguédois, Sophie; Le Bissonnais, Yves; Šimůnek, Jirka

    2011-06-01

    SummaryA comprehensive description of water flow in environmental and agricultural systems requires an account of both surface and subsurface pathways. We present a new model which combines a 1D overland flow model and the 2D subsurface flow HYDRUS-2D model, and uses the multi-objective global search method AMALGAM for inverse parameter estimation. Furthermore, we present data from bench-scale flow experiments which were conducted with two 5-m long replicate soil channels. While rainfall was applied, surface runoff was recorded at the downstream end of the soil channel, subsurface drainage waters were sampled at three positions equally spaced along the channels, and pressure heads were recorded at five depths. The experimental observations were used to evaluate the performance of our modeling system. The complexity of the modeling approach was increased in three steps. First, only runoff and total drainage were simulated, then drainage flows from individual compartments were additionally evaluated, and finally a surface crust and immobile soil water were also considered. The results showed that a good match between measured and observed surface runoff and total drainage does not guarantee accurate representation of the flow process. An inspection of the Pareto results of different multiobjective calibration runs revealed a significant trade-off between individual objectives, showing that no single solution existed to match spatial variability in the flow. In spite of the observed crust formation, its consideration in the more complex model structure did not significantly improve the fit between the model and measurements. Accounting for immobile water regions only slightly improved the fit for one of the two replicate soil channels. Discrepancies between relatively complex model simulations and seemingly simple soil channel experiments suggest the presence of additional unknowns, such as heterogeneity of the soil hydraulic properties. Nevertheless, with its

  13. Particulate phosphorus and sediment in surface runoff and drainflow from clayey soils.

    PubMed

    Uusitalo, R; Turtola, E; Kauppila, T; Lilja, T

    2001-01-01

    Recent work has shown that a significant portion of the total loss of phosphorus (P) from agricultural soils may occur via subsurface drainflow. The aim of this study was to compare the concentrations of different P forms in surface and subsurface runoff, and to assess the potential algal availability of particulate phosphorus (PP) in runoff waters. The material consisted of 91 water-sample pairs (surface runoff vs. subsurface drainage waters) from two artificially drained clayey soils (a Typic Cryaquept and an Aeric Cryaquept) and was analyzed for total suspended solids (TSS), total phosphorus (TP), dissolved molybdate-reactive phosphorus (DRP), and anion exchange resin-extractable phosphorus (AER-P). On the basis of these determinations, we calculated the concentrations of PP, desorbable particulate phosphorus (PPi), and particulate unavailable (nondesorbable) phosphorus (PUP). Some water samples and the soils were also analyzed for 137Cs activity and particle-size distribution. The major P fraction in the waters studied was PP and, on average, only 7% of it was desorbable by AER. However, a mean of 47% of potentially bioavailable P (AER-P) consisted of PPi. The suspended soil material carried by drainflow contained as much PPi (47-79 mg kg-1) as did the surface runoff sediment (45-82 mg kg-1). The runoff sediments were enriched in clay-sized particles and 137Cs by a factor of about two relative to the surface soils. Our results show that desorbable PP derived from topsoil may be as important a contributor to potentially algal-available P as DRP in both surface and subsurface runoff from clayey soils.

  14. Controlling factors of surface soil moisture temporal stability at watershed scale

    NASA Astrophysics Data System (ADS)

    Wei, Lingna; Chen, Xi; Dong, Jianzhi; Gao, Man

    2016-04-01

    Soil moisture plays a significant role in the land surface-atmosphere interactions. Temporal stability was frequently used for estimating areal mean soil moisture using limited number of point measurements. This study investigated the factors that determine soil moisture temporal stability using simulated high spatial resolution soil moisture data at watershed scale. Results show locations under dominate vegetation cover and with low topographic wetness index (TI) values are likely to provide reasonable areal mean soil moisture estimates. We demonstrated that including the information of vegetation cover and TI can effectively reduce the number of the sampling locations that required for determining the representative point. The length of sampling period is also shown to be important in correctly determining the representative point. When 10 sampling points were used, a sampling period of approximately 300 days can provide robust areal mean soil moisture estimates of the entire study period of 9 years. The presented study may be useful for improving our skills in applying the temporal stability method for areal mean soil moisture estimating, and hence remote sensing product validation.

  15. PARTITION COEFFICIENTS FOR METALS IN SURFACE WATER, SOIL, AND WASTE

    EPA Science Inventory

    This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Protection Agency. Partition ...

  16. PARTITION COEFFICIENTS FOR METALS IN SURFACE WATER, SOIL, AND WASTE

    EPA Science Inventory

    This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Protection Agency. Partition ...

  17. Modelling Soil Heat and Water Flow as a Coupled Process in Land Surface Models

    NASA Astrophysics Data System (ADS)

    García González, Raquel; Verhoef, Anne; Vidale, Pier Luigi; Braud, Isabelle

    2010-05-01

    To improve model estimates of soil water and heat flow by land surface models (LSMs), in particular in the first few centimetres of the near-surface soil profile, we have to consider in detail all the relevant physical processes involved (see e.g. Milly, 1982). Often, thermal and iso-thermal vapour fluxes in LSMs are neglected and the simplified Richard's equation is used as a result. Vapour transfer may affect the water fluxes and heat transfer in LSMs used for hydrometeorological and climate simulations. Processes occurring in the top 50 cm soil may be relevant for water and heat flux dynamics in the deeper layers, as well as for estimates of evapotranspiration and heterotrophic respiration, or even for climate and weather predictions. Water vapour transfer, which was not incorporated in previous versions of the MOSES/JULES model (Joint UK Land Environment Simulator; Cox et al., 1999), has now been implemented. Furthermore, we also assessed the effect of the soil vertical resolution on the simulated soil moisture and temperature profiles and the effect of the processes occurring at the upper boundary, mainly in terms of infiltration rates and evapotranspiration. SiSPAT (Simple Soil Plant Atmosphere Transfer Model; Braud et al., 1995) was initially used to quantify the changes that we expect to find when we introduce vapour transfer in JULES, involving parameters such as thermal vapour conductivity and diffusivity. Also, this approach allows us to compare JULES to a more complete and complex numerical model. Water vapour flux varied with soil texture, depth and soil moisture content, but overall our results suggested that water vapour fluxes change temperature gradients in the entire soil profile and introduce an overall surface cooling effect. Increasing the resolution smoothed and reduced temperature differences between liquid (L) and liquid/vapour (LV) simulations at all depths, and introduced a temperature increase over the entire soil profile. Thermal

  18. CONSERVB: A numerical method to compute soil water content and temperature profiles under a bare surface

    NASA Technical Reports Server (NTRS)

    Vanbavel, C. H. M.; Lascano, R. J.

    1982-01-01

    A comprehensive, yet fairly simple model of water disposition in a bare soil profile under the sequential impact of rain storms and other atmospheric influences, as they occur from hour to hour is presented. This model is intended mostly to support field studies of soil moisture dynamics by our current team, to serve as a background for the microwave measurements, and, eventually, to serve as a point of departure for soil moisture predictions for estimates based in part upon airborne measurements. The main distinction of the current model is that it accounts not only for the moisture flow in the soil-atmosphere system, but also for the energy flow and, hence, calculates system temperatures. Also, the model is of a dynamic nature, capable of supporting any required degree of resolution in time and space. Much critical testing of the sample is needed before the complexities of the hydrology of a vegetated surface can be related meaningfully to microwave observations.

  19. Elevated soil CO2 efflux at the boundaries between impervious surfaces and urban greenspaces

    NASA Astrophysics Data System (ADS)

    Wu, XiaoGang; Hu, Dan; Ma, ShengLi; Zhang, Xia; Guo, Zhen; Gaston, Kevin J.

    2016-09-01

    Impervious surfaces and greenspaces have significant impacts on ecological processes and ecosystem services in urban areas. However, there have been no systematic studies of how the interaction between the two forms of land cover, and especially their edge effects, influence ecosystem properties. This has made it difficult to evaluate the effectiveness of urban greenspace design in meeting environmental goals. In this study, we investigated edge effects on soil carbon dioxide (CO2) fluxes in Beijing and found that soil CO2 flux rates were averagely 73% higher 10 cm inwards from the edge of greenspaces. Distance, soil temperature, moisture, and their interaction significantly influenced soil CO2 flux rates. The magnitude and distance of edge effects differed among impervious structure types. Current greening policy and design should be adjusted to avoid the carbon sequestration service of greenspaces being limited by their fragmentation.

  20. Using advanced surface complexation models for modelling soil chemistry under forests: Solling forest, Germany.

    PubMed

    Bonten, Luc T C; Groenenberg, Jan E; Meesenburg, Henning; de Vries, Wim

    2011-10-01

    Various dynamic soil chemistry models have been developed to gain insight into impacts of atmospheric deposition of sulphur, nitrogen and other elements on soil and soil solution chemistry. Sorption parameters for anions and cations are generally calibrated for each site, which hampers extrapolation in space and time. On the other hand, recently developed surface complexation models (SCMs) have been successful in predicting ion sorption for static systems using generic parameter sets. This study reports the inclusion of an assemblage of these SCMs in the dynamic soil chemistry model SMARTml and applies this model to a spruce forest site in Solling Germany. Parameters for SCMs were taken from generic datasets and not calibrated. Nevertheless, modelling results for major elements matched observations well. Further, trace metals were included in the model, also using the existing framework of SCMs. The model predicted sorption for most trace elements well.

  1. Be-7 as a tracer for short-term soil surface changes - opportunities and limitations

    NASA Astrophysics Data System (ADS)

    Baumgart, Philipp

    2013-04-01

    Within the last 20 years the cosmogenic nuclide Beryllium-7 was successfully established as a suitable tracer element to detect soil surface changes with a high accuracy. Particularly soil erosion rates from single precipitation events are in the focus of different studies due to the short radioactive half-life of the Be-7 isotope. High sorption at topmost soil particles and immobility at given pH-values enable fine-scaled erosion modelling down to 2 mm increments. But some important challenging limitations require particular attention, starting from sampling up to the final data evaluation. E.g. these are the realisation of the fine increment soil collection, the limiting amount of measurable samples per campaign due to the short radioactive half-life and the specific requirements for the detector measurements. Both, the high potential and the challenging limitations are presented as well as future perspectives of that tracer method.

  2. Open charcoal chamber method for mass measurements of radon exhalation rate from soil surface.

    PubMed

    Tsapalov, Andrey; Kovler, Konstantin; Miklyaev, Peter

    2016-08-01

    Radon exhalation rate from the soil surface can serve as an important criterion in the evaluation of radon hazard of the land. Recently published international standard ISO 11665-7 (2012) is based on the accumulation of radon gas in a closed container. At the same time since 1998 in Russia, as a part of engineering and environmental studies for the construction, radon flux measurements are made using an open charcoal chamber for a sampling duration of 3-5 h. This method has a well-defined metrological justification and was tested in both favorable and unfavorable conditions. The article describes the characteristics of the method, as well as the means of sampling and measurement of the activity of radon absorbed. The results of the metrological study suggest that regardless of the sampling conditions (weather, the mechanism and rate of radon transport in the soil, soil properties and conditions), uncertainty of method does not exceed 20%, while the combined standard uncertainty of radon exhalation rate measured from the soil surface does not exceed 30%. The results of the daily measurements of radon exhalation rate from the soil surface at the experimental site during one year are reported. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Individual-Based Model of Microbial Life on Hydrated Rough Soil Surfaces

    PubMed Central

    Kim, Minsu; Or, Dani

    2016-01-01

    Microbial life in soil is perceived as one of the most interesting ecological systems, with microbial communities exhibiting remarkable adaptability to vast dynamic environmental conditions. At the same time, it is a notoriously challenging system to understand due to its complexity including physical, chemical, and biological factors in synchrony. This study presents a spatially-resolved model of microbial dynamics on idealised rough soil surfaces represented as patches with different (roughness) properties that preserve the salient hydration physics of real surfaces. Cell level microbial interactions are considered within an individual-based formulation including dispersion and various forms of trophic dependencies (competition, mutualism). The model provides new insights into mechanisms affecting microbial community dynamics and gives rise to spontaneous formation of microbial community spatial patterns. The framework is capable of representing many interacting species and provides diversity metrics reflecting surface conditions and their evolution over time. A key feature of the model is its spatial scalability that permits representation of microbial processes from cell-level (micro-metric scales) to soil representative volumes at sub-metre scales. Several illustrative examples of microbial trophic interactions and population dynamics highlight the potential of the proposed modelling framework to quantitatively study soil microbial processes. The model is highly applicable in a wide range spanning from quantifying spatial organisation of multiple species under various hydration conditions to predicting microbial diversity residing in different soils. PMID:26807803

  4. Individual-Based Model of Microbial Life on Hydrated Rough Soil Surfaces.

    PubMed

    Kim, Minsu; Or, Dani

    2016-01-01

    Microbial life in soil is perceived as one of the most interesting ecological systems, with microbial communities exhibiting remarkable adaptability to vast dynamic environmental conditions. At the same time, it is a notoriously challenging system to understand due to its complexity including physical, chemical, and biological factors in synchrony. This study presents a spatially-resolved model of microbial dynamics on idealised rough soil surfaces represented as patches with different (roughness) properties that preserve the salient hydration physics of real surfaces. Cell level microbial interactions are considered within an individual-based formulation including dispersion and various forms of trophic dependencies (competition, mutualism). The model provides new insights into mechanisms affecting microbial community dynamics and gives rise to spontaneous formation of microbial community spatial patterns. The framework is capable of representing many interacting species and provides diversity metrics reflecting surface conditions and their evolution over time. A key feature of the model is its spatial scalability that permits representation of microbial processes from cell-level (micro-metric scales) to soil representative volumes at sub-metre scales. Several illustrative examples of microbial trophic interactions and population dynamics highlight the potential of the proposed modelling framework to quantitatively study soil microbial processes. The model is highly applicable in a wide range spanning from quantifying spatial organisation of multiple species under various hydration conditions to predicting microbial diversity residing in different soils.

  5. Insecticide dissipation from soil and plant surfaces in tropical horticulture of southern Benin, West Africa.

    PubMed

    Rosendahl, Ingrid; Laabs, Volker; Atcha-Ahowé, Cyrien; James, Braima; Amelung, Wulf

    2009-06-01

    In Sub-Saharan Africa, horticulture provides livelihood opportunities for millions of people, especially in urban and peri-urban areas. Although the vegetable agroecosystems are often characterized by intensive pesticide use, risks resulting therefrom are largely unknown under tropical horticultural conditions. The objective of this study therefore was to study the fate of pesticides in two representative horticultural soils (Acrisol and Arenosol) and plants (Solanum macrocarpon L.) after field application and thus to gain first insight on environmental persistence and dispersion of typical insecticides used in vegetable horticulture in Benin, West Africa. On plant surfaces, dissipation was rapid with half lives ranging from 2 to 87 h (alpha-endosulfan < beta-endosulfan < deltamethrin). Soil dissipation was considerably slower than dissipation from plant surfaces with half-lives ranging from 3 (diazinon) to 74 d (total endosulfan), but persistence of pesticides in soil was still reduced compared to temperate climates. Nevertheless, for deltamethrin and endosulfan, a tendency for mid-term accumulation in soil upon repeated applications was observed. The soil and plant surface concentrations of the metabolite endosulfan sulfate increased during the entire trial period, indicating that this compound is a potential long-term pollutant even in tropical environments.

  6. Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types.

    PubMed

    Felt, Deborah; Larson, Steven; Griggs, Chris; Nestler, Catherine; Wynter, Michelle

    2011-05-01

    Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil's particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot's surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.

  7. Global fields of soil moisture and land surface evapotranspiration derived from observed precipitation and surface air temperature

    NASA Technical Reports Server (NTRS)

    Mintz, Y.; Walker, G. K.

    1993-01-01

    The global fields of normal monthly soil moisture and land surface evapotranspiration are derived with a simple water budget model that has precipitation and potential evapotranspiration as inputs. The precipitation is observed and the potential evapotranspiration is derived from the observed surface air temperature with the empirical regression equation of Thornthwaite (1954). It is shown that at locations where the net surface radiation flux has been measured, the potential evapotranspiration given by the Thornthwaite equation is in good agreement with those obtained with the radiation-based formulations of Priestley and Taylor (1972), Penman (1948), and Budyko (1956-1974), and this provides the justification for the use of the Thornthwaite equation. After deriving the global fields of soil moisture and evapotranspiration, the assumption is made that the potential evapotranspiration given by the Thornthwaite equation and by the Priestley-Taylor equation will everywhere be about the same; the inverse of the Priestley-Taylor equation is used to obtain the normal monthly global fields of net surface radiation flux minus ground heat storage. This and the derived evapotranspiration are then used in the equation for energy conservation at the surface of the earth to obtain the global fields of normal monthly sensible heat flux from the land surface to the atmosphere.

  8. Global fields of soil moisture and land surface evapotranspiration derived from observed precipitation and surface air temperature

    NASA Technical Reports Server (NTRS)

    Mintz, Y.; Walker, G. K.

    1993-01-01

    The global fields of normal monthly soil moisture and land surface evapotranspiration are derived with a simple water budget model that has precipitation and potential evapotranspiration as inputs. The precipitation is observed and the potential evapotranspiration is derived from the observed surface air temperature with the empirical regression equation of Thornthwaite (1954). It is shown that at locations where the net surface radiation flux has been measured, the potential evapotranspiration given by the Thornthwaite equation is in good agreement with those obtained with the radiation-based formulations of Priestley and Taylor (1972), Penman